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Ventricular Septal Defects
49
Ventricular Septal Defects AS HOK MURALIDARAN, MD; IRVING SHEN, MD
Definition A ventricular septal defect (VSD) is an opening in the interventricular septum resulting in direct communication between the left and right ventricles. VSDs can be single or multiple. It is the most commonly diagnosed congenital heart anomaly, present in 20% of patients with congenital heart disease.
Embryology Traditionally the ventricular septum is thought to be derived mostly from three sources. The primary fold arising from the apex of the primitive ventricle, eventually becoming the trabecular septum, fuses with the inlet septum, which originates posteroinferiorly, and with the infundibular or conal septum, which extends downward from the conal ridge. Some evidence, however, points to the inlet and the apical trabecular septa originating from the same source.1 The conal ridge fuses with the endocardial cushions to form the membranous portion of the interventricular septum. Fig. 49.1 shows the various components contributing to the formation of the interventricular septum.
Anatomy There are several schemes for classifying VSDs. The traditional classification describes four types based on the location of the VSD: type 1 or supracristal/subarterial/conal, type 2 or perimembranous/paramembranous, type 3 or inlet/atrioventricular canal, and type 4 or muscular2 (Fig. 49.2). A separate classification of “malaligned” defects is often employed to describe VSDs that are part of lesions like tetralogy of Fallot or interrupted aortic arch, in which the conal septum and the other components of the septum are fully formed but are displaced anterior or posterior with respect to each other. Perimembranous defects constitute 80% of the defects with the other types being 5% to 10% each. Subarterial defects are also known as outlet, conal septal, supracristal, or subpulmonary VSDs. They are located beneath the pulmonary valve, and their superior edge is a fibrous ridge between the two semilunar valves. They can be associated with prolapse of the right coronary leaflet of the aortic valve with associated regurgitation. This type of defect is more common in the Asian population. Perimembranous (paramembranous) defects are also known as membranous or infracristal defects. They are located between the anterior and posterior divisions of the septal band and between the conal and trabecular interventricular septum. The lateral border is formed by the tricuspid annulus; the superior border is usually
the aortic annulus. There may be a variable amount of muscular rim at the superior and lateral borders. The defect can extend into the inlet, trabecular, or outlet portions of the interventricular septum. Extension of the defect to the base of the noncoronary leaflet of the aortic valve may cause aortic regurgitation (AR). The conal septum may be anteriorly malaligned as in tetralogy of Fallot, causing right ventricular outflow tract obstruction, or, less commonly, it may be malaligned posteriorly, causing left ventricular outflow tract obstruction. Inlet defects are also called atrioventricular canal-type defects. The posterior margin of the defect runs along the septal leaflet of the tricuspid valve. The anterior leaflet of the mitral valve often has a cleft. The defect extends superiorly to the membranous septum. Muscular defects are located anywhere in the muscular septum. The margins are characteristically muscular. They are frequently multiple. They may be anterior, midmuscular, apical, or in the inlet septum. The latter differs from the inlet or atrioventricular canal-type VSD in that it is separated from the tricuspid valve and membranous septum by muscle tissue. Infundibular or outlet muscular VSDs differ from subarterial VSDs because of the presence of a rim of muscle separating the defect from the annuli of the aortic and pulmonary valves.
Associated Anomalies VSDs can be isolated lesions or part of a variety of major congenital malformations such as tetralogy of Fallot, double-outlet right ventricle, transposition of the great vessels, and truncus arteriosus. Fifty percent of patients with VSDs requiring repair have associated cardiovascular anomalies, most commonly patent ductus arteriosus, atrial septal defect (ASD), aortic coarctation, aortic stenosis, and pulmonary stenosis.3
Pathophysiology and Natural History The dimension of the defect and pulmonary vascular resistance (PVR) determine the blood flow across a VSD (shunt).4 Smaller VSDs are said to be restrictive because there is a pressure gradient across the defect with a greater left ventricular pressure than right ventricular pressure. The left-to-right shunt depends primarily on the pressure differences. Larger defects approximate the size of the aortic annulus and are nonrestrictive with equal right and left ventricular pressures. In these cases the relative resistances in the systemic and pulmonary vasculature determine the left-to-right shunting. PVR is high in the immediate postnatal period and begins to decrease within the first 2 weeks of life.5 For babies with large 597
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Pulmonary channel
Defects
Aortic channel
Conal septum
RA
Right atrioventricular orifice
history study from the Belgian registry on adult congenital heart disease documented a 13% incidence of spontaneous closure of perimembranous VSDs.13 The authors also noted a 3% incidence of infective endocarditis, 3% incidence of progression to moderate to severe aortic valve insufficiency, and a low rate of atrial arrhythmia and heart block in the unrepaired perimembranous VSD group. Of note, the unrepaired patients had a significantly smaller VSD and left-to-right shunt compared with the repaired group.
Diagnosis Membranous interventricular septum
RV Muscular interventricular septum
Figure 49.1 Longitudinal section through the fetal right ventricle and outflow tract displaying the components contributing to the formation of the interventricular septum. RA, Right atrium; RV, right ventricle.
nonrestrictive VSDs the drop in PVR accentuates the left-to-right shunt, leading to a large volume load in the pulmonary circulation, increasing left atrial pressure, and causing left ventricular volume overload. Congestive heart failure (CHF) develops with decreased peripheral perfusion and increased work of breathing, associated with a drop in stroke volume and tissue oxygen delivery. This results in activation of the renin-angiotensin system, which further increases systemic vasoconstriction and the left-to-right shunting, exacerbating the CHF.6-8 If infants with nonrestrictive VSDs remain untreated, the pulmonary overcirculation can eventually lead to a fixed elevation of PVR and pulmonary vascular disease. These changes are not reversible after VSD closure. Eisenmenger complex develops when PVR becomes greater than systemic resistance, reversing the shunt and causing cyanosis. Infants and children with smaller restrictive VSDs remain asymptomatic. Those with larger nonrestrictive VSDs develop increasingly severe CHF within the first several months of life. This manifests as respiratory symptoms and failure to thrive. These infants have an appreciable mortality within the first year if left untreated.9 Children with moderate shunting develop a gradual increase in PVR over time, and as the PVR approaches systemic levels, the degree of shunting decreases with improvement in symptoms. If untreated, such patients go on to develop Eisenmenger complex and die in the third or fourth decade of life. The development of Eisenmenger physiology increases the risk of death 10- to 12-fold and carries a 25-year survival of only 42%.10 Spontaneous closure of VSDs is well documented and is more likely to occur within the first several months of life in patients with smaller defects. Muscular defects are the most likely to close by further septal muscular development. This is based mostly on autopsy studies in which most of the postmortem reports of spontaneously closed defects are of the muscular type.11 Perimembranous VSDs have the next highest rate of spontaneous closure. The mechanism of spontaneous closure of these defects frequently involves the adherence of excess (aneurysmal) tricuspid valve tissue. Before the description of this mechanism in 1970, septal aneurysms were often presumed to be congenital in origin.12 A recent natural
Symptoms Infants with small defects are usually asymptomatic, and the detection of a murmur results in their diagnosis. Moderate defects result in a predisposition to pulmonary infection and varying degrees of growth retardation during the first few years of life but without severe signs of CHF. Larger defects, particularly nonrestrictive VSDs, produce signs and symptoms of CHF early in the first year of life, including tachypnea, poor feeding, sweating, irritability, failure to thrive, and poor weight gain. This symptom complex results from the increased work of breathing and energy expenditure associated with pulmonary overcirculation and poor peripheral perfusion.
Physical Signs Children with smaller defects may present with a harsh holosystolic murmur with no overt signs of CHF. Those patients with larger defects and shunts (pulmonary-to-systemic blood flow ratio [Qp:Qs]; see subsequent discussion) in excess of 2 : 1 may have signs of CHF, including poor growth, tachypnea, poor perfusion with reduced peripheral pulses, a palpable thrill along the left sternal border, and a harsh holosystolic murmur loudest over the fourth intercostal space. There may be a diastolic murmur related to increased blood return to the left atrium. There is accentuation of the second heart sound. Hepatomegaly and pulmonary congestion may be present. Resting oxygen saturation less than 90% before surgical repair is a sign of significantly elevated PVR and portends an increased risk of pulmonary hypertension and death after surgical closure.
Electrocardiography Typical findings on the electrocardiogram include left ventricular hypertrophy and left atrial enlargement reflected in bifid P waves and prominent R and T waves in the inferior leads and V6, particularly with larger defects. Findings of right ventricular hypertrophy with an RSR′ pattern in lead V1 occur later in the disease process.
Chest X-Ray Examination Radiographic findings include cardiomegaly and an enlarged main pulmonary artery shadow. Left atrial enlargement and prominence of the pulmonary vasculature are also seen. These radiographic findings are more notable with larger defects and may be absent or more subtle with small VSDs.
Echocardiography The type, size, number, and location of medium and large VSDs can be accurately defined by two-dimensional transthoracic
CHAPTER 49 Ventricular Septal Defects
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Supracristal Membranous
A
B
Muscular
Inlet
C
D
Figure 49.2 Various types of ventricular septal defects viewed from within the right ventricle. (A) Supracristal or subarterial. (B) Membranous, perimembranous, or paramembranous. (C) Inlet or atrioventricular (AV) canal type. (D) Muscular or trabecular.
echocardiography. Figs. 49.3 to 49.6 demonstrate the four common VSD types based on their location. Left atrial and ventricular dimensions can be measured and may be important in determining the management of a particular defect. Estimates of pulmonary artery pressure can be made using Doppler imaging of the velocity of a tricuspid regurgitant jet, if present. Other associated cardiac anomalies and the relationship of the VSD to the surrounding structures and valves can also be delineated with this modality. In the majority of cases echocardiography provides sufficient information to proceed with closure of the defect or to follow it expectantly. Transesophageal or epicardial echocardiography is particularly important for providing an intraoperative assessment of VSD closure. Small defects can be missed, especially if they are in the apex of the heart or in the vicinity of larger ones, and often reveal themselves after closure of the bigger VSD.
Cardiac Catheterization Cardiac catheterization may be indicated when echocardiographic data are unsatisfactory, in patients with large defects and significant pulmonary hypertension, or if there is doubt about the anatomy of associated lesions. Recent American Heart Association and American Thoracic Society (AHA/ATS) guidelines for pediatric pulmonary hypertension recommend cardiac catheterization to measure PVR index (PVRI) if early repair has not been performed in the first 1 to 2 years of life for a significant VSD.14 Cardiac catheterization can demonstrate the location, size, and number of defects, along with associated cardiac anomalies. It facilitates direct measurement of left and right heart pressures and oxygen saturations (Fig. 49.7), from which quantification of the intracardiac shunt and PVR may be derived.
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Figure 49.3 Transthoracic two-dimensional echocardiogram showing the short-axis view of a supracristal ventricular septal defect (VSD). Note the defect in the 1- to 2-o’clock position at the right ventricular outflow tract. RA, Right atrium; RV, right ventricle.
Figure 49.6 Four-chamber view of a midmuscular ventricular septal defect (VSD). LV, Left ventricle; RV, right ventricle.
Figure 49.4 Short-axis view in a transthoracic echocardiogram of a perimembranous VSD. The defect is seen at the 10-o’clock position close to the tricuspid valve, in contrast to the position of the supracristal defect shown in Fig. 49.3. RV, Right ventricle; TV, tricuspid valve; VSD, ventricular septal defect.
Figure 49.7 Pathophysiology of ventricular septal defect (VSD). Note step-up in O2 saturation from the right atrium (66%) to the right ventricle (86%), indicating left-to-right shunt at the ventricular level. Right ventricular pressure (60/5 mm Hg) is elevated compared with the normal right ventricular pressure but is less than the left ventricular pressure (90/5 mm Hg), indicating that the VSD is restrictive. The pulmonary artery pressure is elevated as well. m, Mean pressure.
Figure 49.5 Four-chamber view of an inlet ventricular septal defect (VSD), displaying its posterior location at the level of the tricuspid and mitral valves. LV, Left ventricle; MV, mitral valve; RV, right ventricle; TV, tricuspid valve.
CHAPTER 49 Ventricular Septal Defects
The shunt fraction is the ratio of pulmonary blood flow (Qp) to systemic blood flow (Qs). It is calculated according to the following formula: Q p:Q s = [( AO2 − MVO2 ) (PVO2 − PaO2 )] where AO2 is the aortic oxygen saturation, MVO2 is the mixed venous oxygen saturation, PaO2 is the pulmonary arterial saturation, and PVO2 is the pulmonary venous saturation.14 One can calculate the PVR using the formula: PVR =
( Mean PAP − PCWP or LAP) × 80 Cardiac Output
where PAP is the pulmonary artery pressure, PCWP is the pulmonary capillary wedge pressure, and LAP is the left atrial pressure. Surgical repair of the VSD is considered safe for PVRI less than 6 Wood units (WU) × m2 (WU • m2) or if the ratio of pulmonary to systemic vascular resistance (PVR/SVR) is less than 0.3.14 The AHA/ATS guidelines recommend testing for vascular reactivity during catheterization using inhaled nitric oxide and oxygen to assess for reversibility of pulmonary hypertension for PVRI that is greater than 6 WU • m2 and for PVR/SVR that is 0.3 or higher. Repair can be beneficial if the vascular bed is reactive but is contraindicated if it is not. In one study, for example, patients with a PVRI of less than 8 WU • m2 had a greater than 90% survival after surgery, whereas patients with a PVRI of greater than 8 WU • m2 had a survival of less than 45%.15 Heart-lung transplantation or lung transplantation with VSD closure is the only surgical option for this group of patients.16 With the availability of newer agents for managing pulmonary hypertension, it is not unreasonable to treat patients with single or multiple pulmonary vasodilators for a period of time and reassess the hemodynamics with cardiac catheterization to revisit candidacy for surgical repair.
Indications for Surgical Repair Infants with a large defect and significant CHF in whom spontaneous closure is unlikely are candidates for early closure, regardless of the patient’s size. A trial of diuretic therapy with or without the addition of digoxin may control the symptoms of CHF and allow the infant to grow. The addition of an angiotensin-converting enzyme (ACE) inhibitor to reduce SVR may be helpful in selected cases. In these cases, surgical repair is typically performed between 3 and 6 months of age. If medical therapy fails, surgical repair should be undertaken promptly and can be done safely even in neonates. Children with moderate-sized defects and shunts greater than 1.5 : 1 generally have mild to moderate elevations of pulmonary artery pressure and resistance. They can be followed until they are up to 5 years of age to maximize the chance of spontaneous closure. Failing the latter, surgical repair may be performed. Patients with subarterial or supracristal VSDs can develop progressive AR due to prolapse of the adjacent aortic valve leaflet caused by Venturi forces associated with left-to-right flow across the defect.17 The risk of aortic valve prolapse increases with increasing defect size. Surgical closure of these defects is usually recommended because the rate of spontaneous closure is low and the risk of developing aortic valve insufficiency is common. These defects should be repaired as soon as there is echocardiographic evidence or physical findings of AR and definitely before significant AR
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develops. Simultaneous aortic valvuloplasty should be considered if the AR has progressed beyond a moderate degree. One study has shown that lesser degrees of AR remained stable after simple defect closure, and more severe regurgitation was associated with a significant need for reintervention despite aortic valvuloplasty at the time of VSD repair.18 A recent study on adults, however, showed that patients older than 40 with unrepaired supracristal VSDs have a lower risk of AR progression than younger patients, questioning the need for routine prophylactic repair in this specific population.19 Some patients with pressure-restrictive VSD by Doppler criteria can still develop progressive left heart dilation due to the “volume unrestrictive” nature of the defect. Although such patients are referred for surgical closure, this practice has been questioned by some based on observations that the left heart dilation often regresses spontaneously over time.20 Children with small VSDs and left-to-right shunts less than 1.5 : 1 generally have no symptoms. Although they are at risk of bacterial endocarditis, close follow-up and prophylactic antibiotic therapy may be considered as an alternative to surgical repair.21 A report from the Swedish registry for congenital heart disease noted a 20- to 30-fold higher incidence of infective endocarditis among adults with small unrepaired VSDs compared with the general population.22 Some would hence recommend surgical closure of small VSDs after an episode of VSD-associated infective endocarditis. Preemptive surgical closure for such small VSDs is controversial. A special situation in the neonatal period occurs when an infant is diagnosed with an aortic coarctation and a concomitant VSD. The optimal management strategy for neonates with this combination of lesions is controversial. A two-stage approach, involving coarctation repair with or without pulmonary artery banding via a left thoracotomy, followed by VSD closure and removal of the band 6 to 12 months later, has been demonstrated to be safe and effective.23,24 A single-stage approach of simultaneous VSD and coarctation repair via a median sternotomy can be performed with comparably low morbidity and mortality.25 A single-stage, twoincision approach is another alternative whereby the coarctation repair is performed via a thoracotomy followed immediately by the VSD repair via sternotomy.26 It is also a reasonable strategy to repair the coarctation through a left thoracotomy and leave the pulmonary artery unbanded. If the infant remains in severe CHF, even after “unloading” of the systemic output with coarctation repair, the VSD can be closed through a sternotomy with a short period of cardiopulmonary bypass (CPB). Pulmonary artery banding is rarely indicated for the treatment of VSD except in some infants with multiple or complex defects and/or contraindications for being placed on CPB (sepsis, intracranial hemorrhage). Banding in this situation controls the heart failure and allows the resolution of comorbid conditions before surgical VSD closure and pulmonary artery debanding.
Operative Management With the patient in supine position a median sternotomy is performed and the thymus subtotally resected to facilitate exposure. The pericardium is opened and suspended. Ascending aortic and bicaval venous cannulation are performed after heparinization. Purse-string sutures should all be elongated and narrow. CPB is established, and, depending on the anticipated complexity of the procedure, cooling anywhere from 34°C to 30°C is begun. The left heart can be decompressed by placing a vent through the left
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Ant. TV leaflet
P. S.
A
Cor. sinus AV node Membranous VSD
B
Figure 49.8 Ventricular septal defect (VSD) closure via the transatrial approach. (A) A right atriotomy has been performed, and the VSD is seen across the tricuspid valve (TV). Note the position of the atrioventricular node (AV node) and the conduction system that runs along the posterior and inferior border of the VSD. (B) A Dacron or PTFE patch is used to close the defect. A portion of the TV suspensory apparatus is being retracted. P., Posterior leaflet; PTFE, polytetrafluoroethylene; S., septal leaflet of the tricuspid valve.
atrial appendage or, more commonly, the right superior pulmonary vein. Cardioplegia is administered in antegrade fashion after crossclamping the aorta and redosed at regular intervals if necessary. For neonates, another option is to use single venous cannulation through the right atrial appendage and perform the repair under hypothermic circulatory arrest at a rectal temperature of 18°C. An oblique right atrial incision is made after the caval snares are secured. Retractors are positioned after placement of stay sutures. The anatomy is inspected through the tricuspid valve. VSDs are ordinarily closed with a patch (usually polytetrafluoroethylene [PTFE], Dacron, bovine, or glutaraldehyde-treated autologous pericardium) unless they are quite small. Patch material can be sewn into place with either interrupted sutures or a continuous technique. Particular care is required with the superior sutures to avoid injury to the aortic valve; inferiorly, sutures are placed away from the margins of the VSD to avoid the conduction tissue. Occasionally exposure of the defect may be compromised by the tricuspid valve or supporting apparatus. In these cases it may be helpful to partially detach the septal leaflet of the tricuspid valve to facilitate exposure of the lateral and inferior borders. The septal leaflet is then repaired with a running polypropylene suture. After repair of the VSD is complete, the tricuspid valve is tested for competence and repaired as necessary. An ASD or patent foramen ovale, if present, is closed. The right atrium is closed, and after deairing the heart the cross-clamp is removed. When deairing and rewarming are complete, the patient is separated from CPB. Ultrafiltration can be undertaken either during CPB or after cessation of CPB but before decannulation and protamine administration. Ideally, intraoperative transesophageal or epicardial echocardiography is used to rule out a residual VSD. Information about tricuspid and aortic valve competence and ventricular function is also obtained using this modality. If there is a question about the significance of a residual VSD, direct measurement of pulmonary artery pressure and simultaneous measurement of oxygen saturations
in the superior vena cava and pulmonary artery can be made, and the Qp:Qs can be estimated. A decision can then be made to go back on bypass to repair the residual defect if the Qp:Qs remains significant (≥1.5 : 1). Rarely, if it is felt that further attempts at repair may be unsuccessful, a pulmonary artery band can be placed to restrict the pulmonary blood flow with plans to repair the residual defects in the future, allowing time for spontaneous regression of the defects and somatic growth. For infants with moderate to severe pulmonary hypertension, placement of a pulmonary artery catheter, left atrial line, and even a peritoneal dialysis catheter should be considered to aid in postoperative management. Inhaled nitric oxide can also be helpful in the postoperative management of this subgroup of patients. The vast majority of membranous and inlet VSDs are closed via the transatrial approach (Fig. 49.8) but can be closed through a ventriculotomy in selected cases. Supracristal defects must be closed through either a ventriculotomy or an incision in the pulmonary artery, with sutures anchored to the pulmonary valve annulus. Muscular VSDs, especially multiple/complex defects remain a surgical challenge. Whereas inlet and midmuscular defects can be repaired through the tricuspid valve, anterior defects are sometimes approached via a right ventriculotomy and apical VSDs through an apical left ventriculotomy. To enhance exposure of these defects, transection of crossing muscle bundles or even the moderator band has been suggested.27 Other described techniques include placing an “oversized patch” on the left ventricular side of the defect and the “sandwich” technique, in which sutures are passed along the inferior rim of an anterior muscular VSD and brought out of the epicardial surface of the right ventricle and tied down, hence obliterating the defect.28 A cardioscope, introduced through the aortic root, can aid in visualization of the muscular defects, permitting direct inspection of the left side of the ventricular septum and illuminating the defects from the right ventricular aspect.
CHAPTER 49 Ventricular Septal Defects
Alternatively, a right-angle clamp introduced through an aortotomy to probe the septum from the left side can be helpful in identifying the defects. Multiple apical defects can be effectively repaired with the septal obliteration technique, in which the defects are excluded from the right ventricular cavity with a pericardial patch.29 A simpler technique involves primary closure of the muscular defects after identifying each VSD with a silk suture passed through the defect from the right ventricle and fished out of the left heart via an incision in the interatrial septum.30 The intraoperative placement of devices designed for transcatheter closure of ASDs or VSDs is another option for muscular defects.31 Periventricular device deployment without the use of CPB has been described by multiple groups—initially in muscular VSDs but more recently also in perimembranous and supracristal defects.32-35 The periventricular approach is usually through a median sternotomy. After placement of a purse-string suture on the right ventricle, a guide wire is introduced through the purse-string suture across the VSD under transesophageal echocardiography guidance. A sheath that is introduced into the right ventricle over the guide wire is used to deploy the closure device across the defect. Extreme care must be taken to avoid a transmural injury to the left ventricular free wall by the guide wire or the introducer.
Postoperative Care Extubation in the operating room for older uncomplicated patients is appropriate. Neonates and infants may require ventilatory support and aggressive diuresis for 24 to 72 hours before safe extubation. If postoperative inotropic support is required, diuresis may not be effective in the initial 24 hours after surgery. On the patient’s admission to the intensive care unit a baseline measurement of hemodynamic parameters is performed. The heart rate and rhythm, arterial blood pressure, central venous pressure, and core and peripheral temperatures are monitored. Left atrial or pulmonary artery pressures may also be monitored in complicated cases or in patients who are at risk for or have exhibited signs of pulmonary hypertension. Admission hematocrit, serum chemistries, serum lactate level, arterial blood gas values, and coagulation parameters are checked. In addition to an electrocardiogram, chest radiography to check support equipment position and the pleural spaces is performed. Estimates of cardiac output are made on the basis of peripheral perfusion and temperature, strength of pedal pulses, urinary output, serum lactate, and acid-base status. Some programs also use nearinfrared spectroscopy routinely or selectively to monitor the adequacy of tissue oxygenation. Volume replacement may be required for low filling pressures. For elevated filling pressures (>10 mm Hg) and low cardiac output, inotropic support is required. A vasodilating agent is used to treat inadequate cardiac output associated with an elevated mean arterial blood pressure. Milrinone works well in this situation. The majority of patients undergoing straightforward VSD closure require minimal if any inotropic support postoperatively and can be extubated fairly promptly. Most benefit from diuresis instituted within 12 hours of surgery and continued until after the institution of enteral feedings. In patients with a large VSD and significant left-to-right shunt, it is not uncommon to find depressed left ventricular function by echocardiography in the immediate postoperative period, especially if their repair was delayed.36 It is felt that an acute change in loading conditions—decreased preload from closure of the defect and an increased afterload from excluding the relatively low-resistance pulmonary circulation—contributes to this finding. Plasma levels
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of brain natriuretic peptide are elevated in the postoperative period compared with their preoperative values and seem to continue to rise for at least 3 days following repair.37 Patients who have long-standing pulmonary overcirculation or preoperative evidence of elevated PVR are prone to pulmonary hypertensive crises early in their postoperative recovery. A pulmonary artery line may be helpful in these patients. A typical pulmonary hypertension protocol to maintain pulmonary vasodilation involves full sedation and paralysis, hyperventilation, strict acid-base control, and fastidious pulmonary toilet. Use of inhaled nitric oxide and inhaled prostacyclin analogues is highly recommended in addition to conventional measures mentioned earlier with transition to oral pulmonary vasodilatory agents if the pulmonary artery pressures remain elevated.14 Early postoperative dysrhythmias occur in up to one-third of patients.38 Supraventricular and junctional ectopic tachycardias are usually accompanied by marked deterioration in cardiac output and must be aggressively treated. Cooling the patient to 33°C or 34°C is effective with simple topical cooling. A peritoneal dialysis catheter, if present, may also be used for this purpose. These interventions require sedation and frequently neuromuscular blockade. Amiodarone, procainamide, dexmedetomidine, or a combination of these agents can be used to treat these tachycardias should the response to cooling be insufficient. Complete heart block is another complication of VSD closure. It is often transient in nature, due to surgical trauma or edema associated with suture placement adjacent to the conduction tissue. Heart block usually resolves in 24 to 48 hours. Disruption of the conduction pathway results in permanent heart block. A contemporary series quoted a 5% incidence of combined temporary and permanent heart block and a 2% incidence of complete heart block requiring a pacemaker implantation.39 All patients undergoing VSD repair should have temporary atrial and ventricular epicardial pacing wires placed at the time of surgery. These temporary wires are useful in both the diagnosis and treatment of dysrhythmias during the early postoperative period. If there is postoperative complete heart block, a transvenous or epicardial permanent pacemaker system is required if sinus rhythm is not restored within 7 to 10 days.
Outcome Mortality rates for isolated VSD closure are less than 1%. For closure of multiple VSDs the rate may be as high as 7%.40 The incidence of residual shunting due to patch dehiscence is very small. On the contrary, it is common to have some degree of residual shunting from small residual defects around the patch, with an incidence reported to be approximately 33%.41 The same study noticed that two-thirds of these residual defects closed by the time of hospital discharge. Fig. 49.9 shows a residual patch leak on echocardiography with color Doppler imaging. Morbidity rates in infants seem to be higher with decreasing operative weight. In patients with postoperative right bundle branch block, there is a tendency toward left ventricular dilation in the long term, which confirms the need for long-term follow-up of these patients.42 Long-term survival is excellent after successful VSD repair.
Interventional Therapy Percutaneous transcatheter closure of VSDs with devices is less well established than device closure of ASDs. This technology has most commonly been used in the treatment of muscular
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patient size because most patients with hemodynamically significant VSDs present with failure to thrive during infancy. Currently in the United States, percutaneous closure of perimembranous VSDs in the cardiac catheterization laboratory is not a recommended or commonly performed procedure. A staged approach to treating infants with multiple VSDs involving initial pulmonary artery banding followed by delayed catheter-based closure of the muscular VSDs that have failed to close spontaneously in the intervening period may prove effective in the management of these challenging patients. As discussed earlier, a combined approach in the operating room could also be effective. As the technology improves, the indications for these procedures will expand. Patient follow-up will be important because the long-term outcomes of these procedures are still being accrued. Figure 49.9 Two-dimensional echocardiogram with color Doppler revealing a residual defect at the border of a patch following closure of a perimembranous defect. LA, Left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle.
VSDs with acceptable results.43 The proximity of vital structures such as the aortic valve and the septal leaflet of the tricuspid valve to the paramembranous VSD makes device closure of this defect more challenging, although newer modifications have been developed. The only US Food and Drug Administration–approved phase I clinical trial for device closure of hemodynamically significant perimembranous VSDs was reported in 2006.44 This multicenter study used the Amplatzer Membranous VSD Occluder (AGA Medical Corp., Golden Valley, MN) in 32 of 35 patients in whom it was attempted. The median age was 7.7 years, and patients under 8 kg were excluded from the study. Although the rate of complete closure by echocardiography was 96% by 6 months, 2 patients required permanent pacemaker implantation at 3 and 16 months post procedure. New AR developed in 53% of patients within 24 hours of the procedure, deceasing to 39% by 6 months. Of the 35 patients, 4 were referred to surgery for either device placement–related significant AR, inadequate device positioning, or difficulty with device retrieval causing entanglement in the tricuspid valve chordae. A total of 6 out of 35 (17%) patients eventually needed a surgical intervention either for pacemaker placement or for VSD closure. A later multi-institutional study narrowed the device closure to a subpopulation of membranous defects that had an associated aneurysm.45 The investigators used the Amplatzer Duct Occluder I device, positioning it within the aneurysm and hence away from the aortic valve and from the crest of the ventricular septum, which correlated with a reduced incidence of new AR and heart block. The authors selected patients with a “wind-sock” appearance of the aneurysm, with very specific inclusion criteria based on the geometry of the aneurysm, the details of which are beyond the scope of this chapter. The device was successfully placed in 19 of 21 selected patients, whose weights were all above 8 kg with a median age of 5 years. A recent meta-analysis of published studies comparing device closure with surgical closure of perimembranous VSDs showed comparable rates of successful closure and short-term complication rates.46 The mean age in the device group was 12.2 years, whereas that of the surgical cohort was 5.5 years. An important current limitation to the application of percutaneously placed devices is
Selected References A complete list of references is available at ExpertConsult.com. 1. Lamers WH, Wessels A, Verbeek FJ, et al. New findings concerning ventricular septation in the human heart. Implications for maldevelopment. Circulation. 1992;86(4):1194–1205. 2. Jacobs JP, Burke RP, Quintessenza JA, Mavroudis C. Congenital heart surgery nomenclature and database project: ventricular septal defect. Ann Thorac Surg. 2000;69(suppl 4):S25–S35. 12. Misra KP, Hildner FJ, Cohen LS, Narula OS, Samet P. Aneurysm of the membranous ventricular septum. A mechanism for spontaneous closure of ventricular septal defect. N Engl J Med. 1970;283(2):58–61. 13. Gabriels C, De Backer J, Pasquet A, et al. Long-term outcome of patients with perimembranous ventricular septal defect: results from the Belgian registry on adult congenital heart disease. Cardiology. 2017;136(3):147–155. 14. Abman SH, Hansmann G, Archer SL, et al. Pediatric pulmonary hypertension: guidelines from the American Heart Association and American Thoracic Society. Circulation. 2015;132(21):2037–2099. 19. Egbe AC, Poterucha JT, Dearani JA, Warnes CA. Supracristal ventricular septal defect in adults: Is it time for a paradigm shift? Int J Cardiol. 2015;198:9–14. 20. Kleinman CS, Tabibian M, Starc TJ, Hsu DT, Gersony WM. Spontaneous regression of left ventricular dilation in children with restrictive ventricular septal defects. J Pediatr. 2007;150(6):583– 586. 22. Berglund E, Johansson B, Dellborg M, et al. High incidence of infective endocarditis in adults with congenital ventricular septal defect. Heart. 2016. 26. Kanter KR, Mahle WT, Kogon BE, Kirshbom PM. What is the optimal management of infants with coarctation and ventricular septal defect? Ann Thorac Surg. 2007;84(2):612–618, discussion 618. 27. Seddio F, Reddy VM, McElhinney DB, Tworetzky W, Silverman NH, Hanley FL. Multiple ventricular septal defects: how and when should they be repaired? J Thorac Cardiovasc Surg. 1999;117(1):134–139, discussion 139–140. 28. Kitagawa T, Durham LA 3rd, Mosca RS, Bove EL. Techniques and results in the management of multiple ventricular septal defects. J Thorac Cardiovasc Surg. 1998;115(4):848–856. 30. Talwar S, Bhoje A, Airan B. A simple technique for closing multiple muscular and apical ventricular septal defects. J Card Surg. 2015;30(9):731–734. 32. Bacha EA, Cao QL, Starr JP, Waight D, Ebeid MR, Hijazi ZM. Perventricular device closure of muscular ventricular septal defects on the beating heart: technique and results. J Thorac Cardiovasc Surg. 2003;126(6):1718–1723. 33. Omelchenko A, Gorbatykh Y, Voitov A, Zaitsev G, BogachevProkophiev A, Karaskov A. Perventricular device closure of ventricular septal defects: results in patients less than 1 year of age. Interact Cardiovasc Thorac Surg. 2016;22(1):53–56.
34. Hongxin L, Wenbin G, Liang F, Zhang HZ, Zhu M, Zhang WL. Perventricular device closure of a doubly committed juxtaarterial ventricular septal defect through a left parasternal approach: midterm follow-up results. J Cardiothorac Surg. 2015;10:175. 35. Zhang S, Zhu D, An Q, Tang H, Li D, Lin K. Minimally invasive periventricular device closure of doubly committed sub-arterial ventricular septal defects: single center long-term follow-up results. J Cardiothorac Surg. 2015;10:119. 36. Pacileo G, Pisacane C, Russo MG, et al. Left ventricular mechanics after closure of ventricular septal defect: influence of size of the defect and age at surgical repair. Cardiol Young. 1998;8(3):320–328. 37. Mainwaring RD, Parise C, Wright SB, Juris AL, Achtel RA, Fallah H. Brain natriuretic peptide levels before and after ventricular septal defect repair. Ann Thorac Surg. 2007;84(6):2066–2069. 39. Anderson BR, Stevens KN, Nicolson SC, et al. Contemporary outcomes of surgical ventricular septal defect closure. J Thorac Cardiovasc Surg. 2013;145(3):641–647. 41. Preminger TJ, Sanders SP, van der Velde ME, Castaneda AR, Lock JE. “Intramural” residual interventricular defects after repair of conotruncal malformations. Circulation. 1994;89(1):236– 242.
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42. Veeram Reddy SR, Du W, Zilberman MV. Left ventricular mechanical synchrony and global systolic function in pediatric patients late after ventricular septal defect patch closure: a three-dimensional echocardiographic study. Congenit Heart Dis. 2009;4(6):454–458. 43. Holzer R, Balzer D, Cao QL, Lock K, Hijazi ZM. Amplatzer muscular ventricular septal defect I. Device closure of muscular ventricular septal defects using the Amplatzer muscular ventricular septal defect occluder: immediate and mid-term results of a U.S. registry. J Am Coll Cardiol. 2004;43(7):1257–1263. 44. Fu YC, Bass J, Amin Z, et al. Transcatheter closure of perimembranous ventricular septal defects using the new Amplatzer membranous VSD occluder: results of the U.S. phase I trial. J Am Coll Cardiol. 2006;47(2):319–325. 45. El Said HG, Bratincsak A, Gordon BM, Moore JW. Closure of perimembranous ventricular septal defects with aneurysmal tissue using the Amplazter Duct Occluder I: lessons learned and medium term follow up. Catheter Cardiovasc Interv. 2012;80(6):895–903. 46. Saurav A, Kaushik M, Mahesh Alla V, et al. Comparison of percutaneous device closure versus surgical closure of peri-membranous ventricular septal defects: A systematic review and meta-analysis. Catheter Cardiovasc Interv. 2015;86(6):1048–1056.
References 1. Lamers WH, Wessels A, Verbeek FJ, et al. New findings concerning ventricular septation in the human heart. Implications for maldevelopment. Circulation. 1992;86(4):1194–1205. 2. Jacobs JP, Burke RP, Quintessenza JA, Mavroudis C. Congenital Heart Surgery Nomenclature and Database Project: ventricular septal defect. Ann Thorac Surg. 2000;69(suppl 4):S25–S35. 3. E A. Ventricular septal defect. In: Baue AEGA, Hammond GL, et al, eds. Glenn’s Thoracic and Cardiovascular Surgery. Norwalk CT: Appleton & Lange; 1991:1007–1016. 4. Lucas RV Jr, Adams P Jr, Anderson RC, Meyne NG, Lillehei CW, Varco RL. The natural history of isolated ventricular septal defect. A serial physiologic study. Circulation. 1961;24:1372–1387. 5. Kirklin JWB-BB. Ventricular septal defect. In: Kirklin JWB-BB, ed. Cardiac Surgery. New York: Churchill Livingstone; 1993:751–764. 6. Boucek MM, Chang R, Synhorst DP. Reninangiotensin II response to the hemodynamic pathology of ovines with ventricular septal defect. Circ Res. 1989;64(3):524–531. 7. Gidding SS, Bessel M. Hemodynamic correlates of clinical severity in isolated ventricular septal defect. Pediatr Cardiol. 1993;14(3):135–139. 8. Scammell AM, Diver MJ. Plasma renin activity in infants with congenital heart disease. Arch Dis Child. 1987;62(11):1136–1138. 9. Rein JG, Freed MD, Norwood WI, Castaneda AR. Early and late results of closure of ventricular septal defect in infancy. Ann Thorac Surg. 1977;24(1):19–27. 10. Kidd L, Driscoll DJ, Gersony WM, et al. Second natural history study of congenital heart defects. Results of treatment of patients with ventricular septal defects. Circulation. 1993;87(suppl 2):I38–I51. 11. Suzuki H. Spontaneous closure of ventricular septal defects. Anatomic evidence in six adult patients. Am J Clin Pathol. 1969;52(4):391–402. 12. Misra KP, Hildner FJ, Cohen LS, Narula OS, Samet P. Aneurysm of the membranous ventricular septum. A mechanism for spontaneous closure of ventricular septal defect. N Engl J Med. 1970;283(2):58–61. 13. Gabriels C, De Backer J, Pasquet A, et al. Long-term outcome of patients with perimembranous ventricular septal defect: results from the belgian registry on adult congenital heart disease. Cardiology. 2017;136(3):147–155. 14. Abman SH, Hansmann G, Archer SL, et al. Pediatric pulmonary hypertension: guidelines from the american heart association and american thoracic society. Circulation. 2015;132(21):2037–2099. 15. Yamaki S, Mohri H, Haneda K, Endo M, Akimoto H. Indications for surgery based on lung biopsy in cases of ventricular septal defect and/or patent ductus arteriosus
CHAPTER 49 Ventricular Septal Defects
with severe pulmonary hypertension. Chest. 1989;96(1):31–39. 16. Haworth SG. Pulmonary vascular disease in ventricular septal defect: structural and functional correlations in lung biopsies from 85 patients, with outcome of intracardiac repair. J Pathol. 1987;152(3):157–168. 17. Tohyama K, Satomi G, Momma K. Aortic valve prolapse and aortic regurgitation associated with subpulmonic ventricular septal defect. Am J Cardiol. 1997;79(9):1285–1289. 18. Cheung YF, Chiu CS, Yung TC, Chau AK. Impact of preoperative aortic cusp prolapse on long-term outcome after surgical closure of subarterial ventricular septal defect. Ann Thorac Surg. 2002;73(2):622–627. 19. Egbe AC, Poterucha JT, Dearani JA, Warnes CA. Supracristal ventricular septal defect in adults: Is it time for a paradigm shift? Int J Cardiol. 2015;198:9–14. 20. Kleinman CS, Tabibian M, Starc TJ, Hsu DT, Gersony WM. Spontaneous regression of left ventricular dilation in children with restrictive ventricular septal defects. J Pediatr. 2007;150(6):583–586. 21. Gersony WM, Hayes CJ. Bacterial endocarditis in patients with pulmonary stenosis, aortic stenosis, or ventricular septal defect. Circulation. 1977;56(suppl 1):I84–I87. 22. Berglund E, Johansson B, Dellborg M, et al. High incidence of infective endocarditis in adults with congenital ventricular septal defect. Heart. 2016. 23. Isomatsu Y, Imai Y, Shin’oka T, Aoki M, Sato K. Coarctation of the aorta and ventricular septal defect: should we perform a single-stage repair? J Thorac Cardiovasc Surg. 2001;122(3):524–528. 24. Alsoufi B, Cai S, Coles JG, Williams WG, Van Arsdell GS, Caldarone CA. Outcomes of different surgical strategies in the treatment of neonates with aortic coarctation and associated ventricular septal defects. Ann Thorac Surg. 2007;84(4):1331–1336, discussion 1336-1337. 25. Gaynor JW, Wernovsky G, Rychik J, Rome JJ, DeCampli WM, Spray TL. Outcome following single-stage repair of coarctation with ventricular septal defect. Eur J Cardiothorac Surg. 2000;18(1):62–67. 26. Kanter KR, Mahle WT, Kogon BE, Kirshbom PM. What is the optimal management of infants with coarctation and ventricular septal defect? Ann Thorac Surg. 2007;84(2):612–618, discussion 618. 27. Seddio F, Reddy VM, McElhinney DB, Tworetzky W, Silverman NH, Hanley FL. Multiple ventricular septal defects: how and when should they be repaired? J Thorac Cardiovasc Surg. 1999;117(1):134–139, discussion 139-140. 28. Kitagawa T, Durham LA 3rd, Mosca RS, Bove EL. Techniques and results in the management of multiple ventricular septal defects. J Thorac Cardiovasc Surg. 1998;115(4):848–856. 29. Black MD, Shukla V, Rao V, Smallhorn JF, Freedom RM. Repair of isolated multiple
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muscular ventricular septal defects: the septal obliteration technique. Ann Thorac Surg. 2000;70(1):106–110. 30. Talwar S, Bhoje A, Airan B. A simple technique for closing multiple muscular and apical ventricular septal defects. J Card Surg. 2015;30(9):731–734. 31. Okubo M, Benson LN, Nykanen D, et al. Outcomes of intraoperative device closure of muscular ventricular septal defects. Ann Thorac Surg. 2001;72(2):416–423. 32. Bacha EA, Cao QL, Starr JP, Waight D, Ebeid MR, Hijazi ZM. Perventricular device closure of muscular ventricular septal defects on the beating heart: technique and results. J Thorac Cardiovasc Surg. 2003;126(6):1718–1723. 33. Omelchenko A, Gorbatykh Y, Voitov A, Zaitsev G, Bogachev-Prokophiev A, Karaskov A. Perventricular device closure of ventricular septal defects: results in patients less than 1 year of age. Interact Cardiovasc Thorac Surg. 2016;22(1):53–56. 34. Hongxin L, Wenbin G, Liang F, Zhang HZ, Zhu M, Zhang WL. Perventricular device closure of a doubly committed juxtaarterial ventricular septal defect through a left parasternal approach: midterm follow-up results. J Cardiothorac Surg. 2015;10:175. 35. Zhang S, Zhu D, An Q, Tang H, Li D, Lin K. Minimally invasive perventricular device closure of doubly committed sub-arterial ventricular septal defects: single center longterm follow-up results. J Cardiothorac Surg. 2015;10:119. 36. Pacileo G, Pisacane C, Russo MG, et al. Left ventricular mechanics after closure of ventricular septal defect: influence of size of the defect and age at surgical repair. Cardiol Young. 1998;8(3):320–328. 37. Mainwaring RD, Parise C, Wright SB, Juris AL, Achtel RA, Fallah H. Brain natriuretic peptide levels before and after ventricular septal defect repair. Ann Thorac Surg. 2007;84(6):2066–2069. 38. Pfammatter JP, Wagner B, Berdat P, et al. Procedural factors associated with early postoperative arrhythmias after repair of congenital heart defects. J Thorac Cardiovasc Surg. 2002;123(2):258–262. 39. Anderson BR, Stevens KN, Nicolson SC, et al. Contemporary outcomes of surgical ventricular septal defect closure. J Thorac Cardiovasc Surg. 2013;145(3):641–647. 40. Serraf A, Lacour-Gayet F, Bruniaux J, et al. Surgical management of isolated multiple ventricular septal defects. Logical approach in 130 cases. J Thorac Cardiovasc Surg. 1992;103(3):437–442, discussion 443. 41. Preminger TJ, Sanders SP, van der Velde ME, Castaneda AR, Lock JE. Intramural” residual interventricular defects after repair of conotruncal malformations. Circulation. 1994;89(1):236–242. 42. Veeram Reddy SR, Du W, Zilberman MV. Left ventricular mechanical synchrony and global systolic function in pediatric patients late after ventricular septal defect patch closure: a three-dimensional
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echocardiographic study. Congenit Heart Dis. 2009;4(6):454–458. 43. Holzer R, Balzer D, Cao QL, Lock K, Hijazi ZM, Amplatzer Muscular Ventricular Septal Defect I. Device closure of muscular ventricular septal defects using the Amplatzer muscular ventricular septal defect occluder: immediate and mid-term results of a U.S. registry. J Am Coll Cardiol. 2004;43(7):1257–1263.
44. Fu YC, Bass J, Amin Z, et al. Transcatheter closure of perimembranous ventricular septal defects using the new Amplatzer membranous VSD occluder: results of the U.S. phase I trial. J Am Coll Cardiol. 2006;47(2):319–325. 45. El Said HG, Bratincsak A, Gordon BM, Moore JW. Closure of perimembranous ventricular septal defects with aneurysmal tissue using the Amplazter Duct Occluder I: lessons
learned and medium term follow up. Catheter Cardiovasc Interv. 2012;80(6):895–903. 46. Saurav A, Kaushik M, Mahesh Alla V, et al. Comparison of percutaneous device closure versus surgical closure of peri-membranous ventricular septal defects: a systematic review and meta-analysis. Catheter Cardiovasc Interv. 2015;86(6):1048–1056.
Ventricular Septal Defects AS HOK MURALIDARAN, MD; IRVING SHEN, MD
Definition A ventricular septal defect (VSD) is an opening in the interventricular septum resulting in direct communication between the left and right ventricles. VSDs can be single or multiple. It is the most commonly diagnosed congenital heart anomaly, present in 20% of patients with congenital heart disease.
Embryology Traditionally the ventricular septum is thought to be derived mostly from three sources. The primary fold arising from the apex of the primitive ventricle, eventually becoming the trabecular septum, fuses with the inlet septum, which originates posteroinferiorly, and with the infundibular or conal septum, which extends downward from the conal ridge. Some evidence, however, points to the inlet and the apical trabecular septa originating from the same source.1 The conal ridge fuses with the endocardial cushions to form the membranous portion of the interventricular septum. Fig. 49.1 shows the various components contributing to the formation of the interventricular septum.
Anatomy There are several schemes for classifying VSDs. The traditional classification describes four types based on the location of the VSD: type 1 or supracristal/subarterial/conal, type 2 or perimembranous/paramembranous, type 3 or inlet/atrioventricular canal, and type 4 or muscular2 (Fig. 49.2). A separate classification of “malaligned” defects is often employed to describe VSDs that are part of lesions like tetralogy of Fallot or interrupted aortic arch, in which the conal septum and the other components of the septum are fully formed but are displaced anterior or posterior with respect to each other. Perimembranous defects constitute 80% of the defects with the other types being 5% to 10% each. Subarterial defects are also known as outlet, conal septal, supracristal, or subpulmonary VSDs. They are located beneath the pulmonary valve, and their superior edge is a fibrous ridge between the two semilunar valves. They can be associated with prolapse of the right coronary leaflet of the aortic valve with associated regurgitation. This type of defect is more common in the Asian population. Perimembranous (paramembranous) defects are also known as membranous or infracristal defects. They are located between the anterior and posterior divisions of the septal band and between the conal and trabecular interventricular septum. The lateral border is formed by the tricuspid annulus; the superior border is usually
the aortic annulus. There may be a variable amount of muscular rim at the superior and lateral borders. The defect can extend into the inlet, trabecular, or outlet portions of the interventricular septum. Extension of the defect to the base of the noncoronary leaflet of the aortic valve may cause aortic regurgitation (AR). The conal septum may be anteriorly malaligned as in tetralogy of Fallot, causing right ventricular outflow tract obstruction, or, less commonly, it may be malaligned posteriorly, causing left ventricular outflow tract obstruction. Inlet defects are also called atrioventricular canal-type defects. The posterior margin of the defect runs along the septal leaflet of the tricuspid valve. The anterior leaflet of the mitral valve often has a cleft. The defect extends superiorly to the membranous septum. Muscular defects are located anywhere in the muscular septum. The margins are characteristically muscular. They are frequently multiple. They may be anterior, midmuscular, apical, or in the inlet septum. The latter differs from the inlet or atrioventricular canal-type VSD in that it is separated from the tricuspid valve and membranous septum by muscle tissue. Infundibular or outlet muscular VSDs differ from subarterial VSDs because of the presence of a rim of muscle separating the defect from the annuli of the aortic and pulmonary valves.
Associated Anomalies VSDs can be isolated lesions or part of a variety of major congenital malformations such as tetralogy of Fallot, double-outlet right ventricle, transposition of the great vessels, and truncus arteriosus. Fifty percent of patients with VSDs requiring repair have associated cardiovascular anomalies, most commonly patent ductus arteriosus, atrial septal defect (ASD), aortic coarctation, aortic stenosis, and pulmonary stenosis.3
Pathophysiology and Natural History The dimension of the defect and pulmonary vascular resistance (PVR) determine the blood flow across a VSD (shunt).4 Smaller VSDs are said to be restrictive because there is a pressure gradient across the defect with a greater left ventricular pressure than right ventricular pressure. The left-to-right shunt depends primarily on the pressure differences. Larger defects approximate the size of the aortic annulus and are nonrestrictive with equal right and left ventricular pressures. In these cases the relative resistances in the systemic and pulmonary vasculature determine the left-to-right shunting. PVR is high in the immediate postnatal period and begins to decrease within the first 2 weeks of life.5 For babies with large 597
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Aortic channel
Conal septum
RA
Right atrioventricular orifice
history study from the Belgian registry on adult congenital heart disease documented a 13% incidence of spontaneous closure of perimembranous VSDs.13 The authors also noted a 3% incidence of infective endocarditis, 3% incidence of progression to moderate to severe aortic valve insufficiency, and a low rate of atrial arrhythmia and heart block in the unrepaired perimembranous VSD group. Of note, the unrepaired patients had a significantly smaller VSD and left-to-right shunt compared with the repaired group.
Diagnosis Membranous interventricular septum
RV Muscular interventricular septum
Figure 49.1 Longitudinal section through the fetal right ventricle and outflow tract displaying the components contributing to the formation of the interventricular septum. RA, Right atrium; RV, right ventricle.
nonrestrictive VSDs the drop in PVR accentuates the left-to-right shunt, leading to a large volume load in the pulmonary circulation, increasing left atrial pressure, and causing left ventricular volume overload. Congestive heart failure (CHF) develops with decreased peripheral perfusion and increased work of breathing, associated with a drop in stroke volume and tissue oxygen delivery. This results in activation of the renin-angiotensin system, which further increases systemic vasoconstriction and the left-to-right shunting, exacerbating the CHF.6-8 If infants with nonrestrictive VSDs remain untreated, the pulmonary overcirculation can eventually lead to a fixed elevation of PVR and pulmonary vascular disease. These changes are not reversible after VSD closure. Eisenmenger complex develops when PVR becomes greater than systemic resistance, reversing the shunt and causing cyanosis. Infants and children with smaller restrictive VSDs remain asymptomatic. Those with larger nonrestrictive VSDs develop increasingly severe CHF within the first several months of life. This manifests as respiratory symptoms and failure to thrive. These infants have an appreciable mortality within the first year if left untreated.9 Children with moderate shunting develop a gradual increase in PVR over time, and as the PVR approaches systemic levels, the degree of shunting decreases with improvement in symptoms. If untreated, such patients go on to develop Eisenmenger complex and die in the third or fourth decade of life. The development of Eisenmenger physiology increases the risk of death 10- to 12-fold and carries a 25-year survival of only 42%.10 Spontaneous closure of VSDs is well documented and is more likely to occur within the first several months of life in patients with smaller defects. Muscular defects are the most likely to close by further septal muscular development. This is based mostly on autopsy studies in which most of the postmortem reports of spontaneously closed defects are of the muscular type.11 Perimembranous VSDs have the next highest rate of spontaneous closure. The mechanism of spontaneous closure of these defects frequently involves the adherence of excess (aneurysmal) tricuspid valve tissue. Before the description of this mechanism in 1970, septal aneurysms were often presumed to be congenital in origin.12 A recent natural
Symptoms Infants with small defects are usually asymptomatic, and the detection of a murmur results in their diagnosis. Moderate defects result in a predisposition to pulmonary infection and varying degrees of growth retardation during the first few years of life but without severe signs of CHF. Larger defects, particularly nonrestrictive VSDs, produce signs and symptoms of CHF early in the first year of life, including tachypnea, poor feeding, sweating, irritability, failure to thrive, and poor weight gain. This symptom complex results from the increased work of breathing and energy expenditure associated with pulmonary overcirculation and poor peripheral perfusion.
Physical Signs Children with smaller defects may present with a harsh holosystolic murmur with no overt signs of CHF. Those patients with larger defects and shunts (pulmonary-to-systemic blood flow ratio [Qp:Qs]; see subsequent discussion) in excess of 2 : 1 may have signs of CHF, including poor growth, tachypnea, poor perfusion with reduced peripheral pulses, a palpable thrill along the left sternal border, and a harsh holosystolic murmur loudest over the fourth intercostal space. There may be a diastolic murmur related to increased blood return to the left atrium. There is accentuation of the second heart sound. Hepatomegaly and pulmonary congestion may be present. Resting oxygen saturation less than 90% before surgical repair is a sign of significantly elevated PVR and portends an increased risk of pulmonary hypertension and death after surgical closure.
Electrocardiography Typical findings on the electrocardiogram include left ventricular hypertrophy and left atrial enlargement reflected in bifid P waves and prominent R and T waves in the inferior leads and V6, particularly with larger defects. Findings of right ventricular hypertrophy with an RSR′ pattern in lead V1 occur later in the disease process.
Chest X-Ray Examination Radiographic findings include cardiomegaly and an enlarged main pulmonary artery shadow. Left atrial enlargement and prominence of the pulmonary vasculature are also seen. These radiographic findings are more notable with larger defects and may be absent or more subtle with small VSDs.
Echocardiography The type, size, number, and location of medium and large VSDs can be accurately defined by two-dimensional transthoracic
CHAPTER 49 Ventricular Septal Defects
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Supracristal Membranous
A
B
Muscular
Inlet
C
D
Figure 49.2 Various types of ventricular septal defects viewed from within the right ventricle. (A) Supracristal or subarterial. (B) Membranous, perimembranous, or paramembranous. (C) Inlet or atrioventricular (AV) canal type. (D) Muscular or trabecular.
echocardiography. Figs. 49.3 to 49.6 demonstrate the four common VSD types based on their location. Left atrial and ventricular dimensions can be measured and may be important in determining the management of a particular defect. Estimates of pulmonary artery pressure can be made using Doppler imaging of the velocity of a tricuspid regurgitant jet, if present. Other associated cardiac anomalies and the relationship of the VSD to the surrounding structures and valves can also be delineated with this modality. In the majority of cases echocardiography provides sufficient information to proceed with closure of the defect or to follow it expectantly. Transesophageal or epicardial echocardiography is particularly important for providing an intraoperative assessment of VSD closure. Small defects can be missed, especially if they are in the apex of the heart or in the vicinity of larger ones, and often reveal themselves after closure of the bigger VSD.
Cardiac Catheterization Cardiac catheterization may be indicated when echocardiographic data are unsatisfactory, in patients with large defects and significant pulmonary hypertension, or if there is doubt about the anatomy of associated lesions. Recent American Heart Association and American Thoracic Society (AHA/ATS) guidelines for pediatric pulmonary hypertension recommend cardiac catheterization to measure PVR index (PVRI) if early repair has not been performed in the first 1 to 2 years of life for a significant VSD.14 Cardiac catheterization can demonstrate the location, size, and number of defects, along with associated cardiac anomalies. It facilitates direct measurement of left and right heart pressures and oxygen saturations (Fig. 49.7), from which quantification of the intracardiac shunt and PVR may be derived.
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Figure 49.3 Transthoracic two-dimensional echocardiogram showing the short-axis view of a supracristal ventricular septal defect (VSD). Note the defect in the 1- to 2-o’clock position at the right ventricular outflow tract. RA, Right atrium; RV, right ventricle.
Figure 49.6 Four-chamber view of a midmuscular ventricular septal defect (VSD). LV, Left ventricle; RV, right ventricle.
Figure 49.4 Short-axis view in a transthoracic echocardiogram of a perimembranous VSD. The defect is seen at the 10-o’clock position close to the tricuspid valve, in contrast to the position of the supracristal defect shown in Fig. 49.3. RV, Right ventricle; TV, tricuspid valve; VSD, ventricular septal defect.
Figure 49.7 Pathophysiology of ventricular septal defect (VSD). Note step-up in O2 saturation from the right atrium (66%) to the right ventricle (86%), indicating left-to-right shunt at the ventricular level. Right ventricular pressure (60/5 mm Hg) is elevated compared with the normal right ventricular pressure but is less than the left ventricular pressure (90/5 mm Hg), indicating that the VSD is restrictive. The pulmonary artery pressure is elevated as well. m, Mean pressure.
Figure 49.5 Four-chamber view of an inlet ventricular septal defect (VSD), displaying its posterior location at the level of the tricuspid and mitral valves. LV, Left ventricle; MV, mitral valve; RV, right ventricle; TV, tricuspid valve.
CHAPTER 49 Ventricular Septal Defects
The shunt fraction is the ratio of pulmonary blood flow (Qp) to systemic blood flow (Qs). It is calculated according to the following formula: Q p:Q s = [( AO2 − MVO2 ) (PVO2 − PaO2 )] where AO2 is the aortic oxygen saturation, MVO2 is the mixed venous oxygen saturation, PaO2 is the pulmonary arterial saturation, and PVO2 is the pulmonary venous saturation.14 One can calculate the PVR using the formula: PVR =
( Mean PAP − PCWP or LAP) × 80 Cardiac Output
where PAP is the pulmonary artery pressure, PCWP is the pulmonary capillary wedge pressure, and LAP is the left atrial pressure. Surgical repair of the VSD is considered safe for PVRI less than 6 Wood units (WU) × m2 (WU • m2) or if the ratio of pulmonary to systemic vascular resistance (PVR/SVR) is less than 0.3.14 The AHA/ATS guidelines recommend testing for vascular reactivity during catheterization using inhaled nitric oxide and oxygen to assess for reversibility of pulmonary hypertension for PVRI that is greater than 6 WU • m2 and for PVR/SVR that is 0.3 or higher. Repair can be beneficial if the vascular bed is reactive but is contraindicated if it is not. In one study, for example, patients with a PVRI of less than 8 WU • m2 had a greater than 90% survival after surgery, whereas patients with a PVRI of greater than 8 WU • m2 had a survival of less than 45%.15 Heart-lung transplantation or lung transplantation with VSD closure is the only surgical option for this group of patients.16 With the availability of newer agents for managing pulmonary hypertension, it is not unreasonable to treat patients with single or multiple pulmonary vasodilators for a period of time and reassess the hemodynamics with cardiac catheterization to revisit candidacy for surgical repair.
Indications for Surgical Repair Infants with a large defect and significant CHF in whom spontaneous closure is unlikely are candidates for early closure, regardless of the patient’s size. A trial of diuretic therapy with or without the addition of digoxin may control the symptoms of CHF and allow the infant to grow. The addition of an angiotensin-converting enzyme (ACE) inhibitor to reduce SVR may be helpful in selected cases. In these cases, surgical repair is typically performed between 3 and 6 months of age. If medical therapy fails, surgical repair should be undertaken promptly and can be done safely even in neonates. Children with moderate-sized defects and shunts greater than 1.5 : 1 generally have mild to moderate elevations of pulmonary artery pressure and resistance. They can be followed until they are up to 5 years of age to maximize the chance of spontaneous closure. Failing the latter, surgical repair may be performed. Patients with subarterial or supracristal VSDs can develop progressive AR due to prolapse of the adjacent aortic valve leaflet caused by Venturi forces associated with left-to-right flow across the defect.17 The risk of aortic valve prolapse increases with increasing defect size. Surgical closure of these defects is usually recommended because the rate of spontaneous closure is low and the risk of developing aortic valve insufficiency is common. These defects should be repaired as soon as there is echocardiographic evidence or physical findings of AR and definitely before significant AR
601
develops. Simultaneous aortic valvuloplasty should be considered if the AR has progressed beyond a moderate degree. One study has shown that lesser degrees of AR remained stable after simple defect closure, and more severe regurgitation was associated with a significant need for reintervention despite aortic valvuloplasty at the time of VSD repair.18 A recent study on adults, however, showed that patients older than 40 with unrepaired supracristal VSDs have a lower risk of AR progression than younger patients, questioning the need for routine prophylactic repair in this specific population.19 Some patients with pressure-restrictive VSD by Doppler criteria can still develop progressive left heart dilation due to the “volume unrestrictive” nature of the defect. Although such patients are referred for surgical closure, this practice has been questioned by some based on observations that the left heart dilation often regresses spontaneously over time.20 Children with small VSDs and left-to-right shunts less than 1.5 : 1 generally have no symptoms. Although they are at risk of bacterial endocarditis, close follow-up and prophylactic antibiotic therapy may be considered as an alternative to surgical repair.21 A report from the Swedish registry for congenital heart disease noted a 20- to 30-fold higher incidence of infective endocarditis among adults with small unrepaired VSDs compared with the general population.22 Some would hence recommend surgical closure of small VSDs after an episode of VSD-associated infective endocarditis. Preemptive surgical closure for such small VSDs is controversial. A special situation in the neonatal period occurs when an infant is diagnosed with an aortic coarctation and a concomitant VSD. The optimal management strategy for neonates with this combination of lesions is controversial. A two-stage approach, involving coarctation repair with or without pulmonary artery banding via a left thoracotomy, followed by VSD closure and removal of the band 6 to 12 months later, has been demonstrated to be safe and effective.23,24 A single-stage approach of simultaneous VSD and coarctation repair via a median sternotomy can be performed with comparably low morbidity and mortality.25 A single-stage, twoincision approach is another alternative whereby the coarctation repair is performed via a thoracotomy followed immediately by the VSD repair via sternotomy.26 It is also a reasonable strategy to repair the coarctation through a left thoracotomy and leave the pulmonary artery unbanded. If the infant remains in severe CHF, even after “unloading” of the systemic output with coarctation repair, the VSD can be closed through a sternotomy with a short period of cardiopulmonary bypass (CPB). Pulmonary artery banding is rarely indicated for the treatment of VSD except in some infants with multiple or complex defects and/or contraindications for being placed on CPB (sepsis, intracranial hemorrhage). Banding in this situation controls the heart failure and allows the resolution of comorbid conditions before surgical VSD closure and pulmonary artery debanding.
Operative Management With the patient in supine position a median sternotomy is performed and the thymus subtotally resected to facilitate exposure. The pericardium is opened and suspended. Ascending aortic and bicaval venous cannulation are performed after heparinization. Purse-string sutures should all be elongated and narrow. CPB is established, and, depending on the anticipated complexity of the procedure, cooling anywhere from 34°C to 30°C is begun. The left heart can be decompressed by placing a vent through the left
602
PART V
Defects
Ant. TV leaflet
P. S.
A
Cor. sinus AV node Membranous VSD
B
Figure 49.8 Ventricular septal defect (VSD) closure via the transatrial approach. (A) A right atriotomy has been performed, and the VSD is seen across the tricuspid valve (TV). Note the position of the atrioventricular node (AV node) and the conduction system that runs along the posterior and inferior border of the VSD. (B) A Dacron or PTFE patch is used to close the defect. A portion of the TV suspensory apparatus is being retracted. P., Posterior leaflet; PTFE, polytetrafluoroethylene; S., septal leaflet of the tricuspid valve.
atrial appendage or, more commonly, the right superior pulmonary vein. Cardioplegia is administered in antegrade fashion after crossclamping the aorta and redosed at regular intervals if necessary. For neonates, another option is to use single venous cannulation through the right atrial appendage and perform the repair under hypothermic circulatory arrest at a rectal temperature of 18°C. An oblique right atrial incision is made after the caval snares are secured. Retractors are positioned after placement of stay sutures. The anatomy is inspected through the tricuspid valve. VSDs are ordinarily closed with a patch (usually polytetrafluoroethylene [PTFE], Dacron, bovine, or glutaraldehyde-treated autologous pericardium) unless they are quite small. Patch material can be sewn into place with either interrupted sutures or a continuous technique. Particular care is required with the superior sutures to avoid injury to the aortic valve; inferiorly, sutures are placed away from the margins of the VSD to avoid the conduction tissue. Occasionally exposure of the defect may be compromised by the tricuspid valve or supporting apparatus. In these cases it may be helpful to partially detach the septal leaflet of the tricuspid valve to facilitate exposure of the lateral and inferior borders. The septal leaflet is then repaired with a running polypropylene suture. After repair of the VSD is complete, the tricuspid valve is tested for competence and repaired as necessary. An ASD or patent foramen ovale, if present, is closed. The right atrium is closed, and after deairing the heart the cross-clamp is removed. When deairing and rewarming are complete, the patient is separated from CPB. Ultrafiltration can be undertaken either during CPB or after cessation of CPB but before decannulation and protamine administration. Ideally, intraoperative transesophageal or epicardial echocardiography is used to rule out a residual VSD. Information about tricuspid and aortic valve competence and ventricular function is also obtained using this modality. If there is a question about the significance of a residual VSD, direct measurement of pulmonary artery pressure and simultaneous measurement of oxygen saturations
in the superior vena cava and pulmonary artery can be made, and the Qp:Qs can be estimated. A decision can then be made to go back on bypass to repair the residual defect if the Qp:Qs remains significant (≥1.5 : 1). Rarely, if it is felt that further attempts at repair may be unsuccessful, a pulmonary artery band can be placed to restrict the pulmonary blood flow with plans to repair the residual defects in the future, allowing time for spontaneous regression of the defects and somatic growth. For infants with moderate to severe pulmonary hypertension, placement of a pulmonary artery catheter, left atrial line, and even a peritoneal dialysis catheter should be considered to aid in postoperative management. Inhaled nitric oxide can also be helpful in the postoperative management of this subgroup of patients. The vast majority of membranous and inlet VSDs are closed via the transatrial approach (Fig. 49.8) but can be closed through a ventriculotomy in selected cases. Supracristal defects must be closed through either a ventriculotomy or an incision in the pulmonary artery, with sutures anchored to the pulmonary valve annulus. Muscular VSDs, especially multiple/complex defects remain a surgical challenge. Whereas inlet and midmuscular defects can be repaired through the tricuspid valve, anterior defects are sometimes approached via a right ventriculotomy and apical VSDs through an apical left ventriculotomy. To enhance exposure of these defects, transection of crossing muscle bundles or even the moderator band has been suggested.27 Other described techniques include placing an “oversized patch” on the left ventricular side of the defect and the “sandwich” technique, in which sutures are passed along the inferior rim of an anterior muscular VSD and brought out of the epicardial surface of the right ventricle and tied down, hence obliterating the defect.28 A cardioscope, introduced through the aortic root, can aid in visualization of the muscular defects, permitting direct inspection of the left side of the ventricular septum and illuminating the defects from the right ventricular aspect.
CHAPTER 49 Ventricular Septal Defects
Alternatively, a right-angle clamp introduced through an aortotomy to probe the septum from the left side can be helpful in identifying the defects. Multiple apical defects can be effectively repaired with the septal obliteration technique, in which the defects are excluded from the right ventricular cavity with a pericardial patch.29 A simpler technique involves primary closure of the muscular defects after identifying each VSD with a silk suture passed through the defect from the right ventricle and fished out of the left heart via an incision in the interatrial septum.30 The intraoperative placement of devices designed for transcatheter closure of ASDs or VSDs is another option for muscular defects.31 Periventricular device deployment without the use of CPB has been described by multiple groups—initially in muscular VSDs but more recently also in perimembranous and supracristal defects.32-35 The periventricular approach is usually through a median sternotomy. After placement of a purse-string suture on the right ventricle, a guide wire is introduced through the purse-string suture across the VSD under transesophageal echocardiography guidance. A sheath that is introduced into the right ventricle over the guide wire is used to deploy the closure device across the defect. Extreme care must be taken to avoid a transmural injury to the left ventricular free wall by the guide wire or the introducer.
Postoperative Care Extubation in the operating room for older uncomplicated patients is appropriate. Neonates and infants may require ventilatory support and aggressive diuresis for 24 to 72 hours before safe extubation. If postoperative inotropic support is required, diuresis may not be effective in the initial 24 hours after surgery. On the patient’s admission to the intensive care unit a baseline measurement of hemodynamic parameters is performed. The heart rate and rhythm, arterial blood pressure, central venous pressure, and core and peripheral temperatures are monitored. Left atrial or pulmonary artery pressures may also be monitored in complicated cases or in patients who are at risk for or have exhibited signs of pulmonary hypertension. Admission hematocrit, serum chemistries, serum lactate level, arterial blood gas values, and coagulation parameters are checked. In addition to an electrocardiogram, chest radiography to check support equipment position and the pleural spaces is performed. Estimates of cardiac output are made on the basis of peripheral perfusion and temperature, strength of pedal pulses, urinary output, serum lactate, and acid-base status. Some programs also use nearinfrared spectroscopy routinely or selectively to monitor the adequacy of tissue oxygenation. Volume replacement may be required for low filling pressures. For elevated filling pressures (>10 mm Hg) and low cardiac output, inotropic support is required. A vasodilating agent is used to treat inadequate cardiac output associated with an elevated mean arterial blood pressure. Milrinone works well in this situation. The majority of patients undergoing straightforward VSD closure require minimal if any inotropic support postoperatively and can be extubated fairly promptly. Most benefit from diuresis instituted within 12 hours of surgery and continued until after the institution of enteral feedings. In patients with a large VSD and significant left-to-right shunt, it is not uncommon to find depressed left ventricular function by echocardiography in the immediate postoperative period, especially if their repair was delayed.36 It is felt that an acute change in loading conditions—decreased preload from closure of the defect and an increased afterload from excluding the relatively low-resistance pulmonary circulation—contributes to this finding. Plasma levels
603
of brain natriuretic peptide are elevated in the postoperative period compared with their preoperative values and seem to continue to rise for at least 3 days following repair.37 Patients who have long-standing pulmonary overcirculation or preoperative evidence of elevated PVR are prone to pulmonary hypertensive crises early in their postoperative recovery. A pulmonary artery line may be helpful in these patients. A typical pulmonary hypertension protocol to maintain pulmonary vasodilation involves full sedation and paralysis, hyperventilation, strict acid-base control, and fastidious pulmonary toilet. Use of inhaled nitric oxide and inhaled prostacyclin analogues is highly recommended in addition to conventional measures mentioned earlier with transition to oral pulmonary vasodilatory agents if the pulmonary artery pressures remain elevated.14 Early postoperative dysrhythmias occur in up to one-third of patients.38 Supraventricular and junctional ectopic tachycardias are usually accompanied by marked deterioration in cardiac output and must be aggressively treated. Cooling the patient to 33°C or 34°C is effective with simple topical cooling. A peritoneal dialysis catheter, if present, may also be used for this purpose. These interventions require sedation and frequently neuromuscular blockade. Amiodarone, procainamide, dexmedetomidine, or a combination of these agents can be used to treat these tachycardias should the response to cooling be insufficient. Complete heart block is another complication of VSD closure. It is often transient in nature, due to surgical trauma or edema associated with suture placement adjacent to the conduction tissue. Heart block usually resolves in 24 to 48 hours. Disruption of the conduction pathway results in permanent heart block. A contemporary series quoted a 5% incidence of combined temporary and permanent heart block and a 2% incidence of complete heart block requiring a pacemaker implantation.39 All patients undergoing VSD repair should have temporary atrial and ventricular epicardial pacing wires placed at the time of surgery. These temporary wires are useful in both the diagnosis and treatment of dysrhythmias during the early postoperative period. If there is postoperative complete heart block, a transvenous or epicardial permanent pacemaker system is required if sinus rhythm is not restored within 7 to 10 days.
Outcome Mortality rates for isolated VSD closure are less than 1%. For closure of multiple VSDs the rate may be as high as 7%.40 The incidence of residual shunting due to patch dehiscence is very small. On the contrary, it is common to have some degree of residual shunting from small residual defects around the patch, with an incidence reported to be approximately 33%.41 The same study noticed that two-thirds of these residual defects closed by the time of hospital discharge. Fig. 49.9 shows a residual patch leak on echocardiography with color Doppler imaging. Morbidity rates in infants seem to be higher with decreasing operative weight. In patients with postoperative right bundle branch block, there is a tendency toward left ventricular dilation in the long term, which confirms the need for long-term follow-up of these patients.42 Long-term survival is excellent after successful VSD repair.
Interventional Therapy Percutaneous transcatheter closure of VSDs with devices is less well established than device closure of ASDs. This technology has most commonly been used in the treatment of muscular
604 PART V
Defects
patient size because most patients with hemodynamically significant VSDs present with failure to thrive during infancy. Currently in the United States, percutaneous closure of perimembranous VSDs in the cardiac catheterization laboratory is not a recommended or commonly performed procedure. A staged approach to treating infants with multiple VSDs involving initial pulmonary artery banding followed by delayed catheter-based closure of the muscular VSDs that have failed to close spontaneously in the intervening period may prove effective in the management of these challenging patients. As discussed earlier, a combined approach in the operating room could also be effective. As the technology improves, the indications for these procedures will expand. Patient follow-up will be important because the long-term outcomes of these procedures are still being accrued. Figure 49.9 Two-dimensional echocardiogram with color Doppler revealing a residual defect at the border of a patch following closure of a perimembranous defect. LA, Left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle.
VSDs with acceptable results.43 The proximity of vital structures such as the aortic valve and the septal leaflet of the tricuspid valve to the paramembranous VSD makes device closure of this defect more challenging, although newer modifications have been developed. The only US Food and Drug Administration–approved phase I clinical trial for device closure of hemodynamically significant perimembranous VSDs was reported in 2006.44 This multicenter study used the Amplatzer Membranous VSD Occluder (AGA Medical Corp., Golden Valley, MN) in 32 of 35 patients in whom it was attempted. The median age was 7.7 years, and patients under 8 kg were excluded from the study. Although the rate of complete closure by echocardiography was 96% by 6 months, 2 patients required permanent pacemaker implantation at 3 and 16 months post procedure. New AR developed in 53% of patients within 24 hours of the procedure, deceasing to 39% by 6 months. Of the 35 patients, 4 were referred to surgery for either device placement–related significant AR, inadequate device positioning, or difficulty with device retrieval causing entanglement in the tricuspid valve chordae. A total of 6 out of 35 (17%) patients eventually needed a surgical intervention either for pacemaker placement or for VSD closure. A later multi-institutional study narrowed the device closure to a subpopulation of membranous defects that had an associated aneurysm.45 The investigators used the Amplatzer Duct Occluder I device, positioning it within the aneurysm and hence away from the aortic valve and from the crest of the ventricular septum, which correlated with a reduced incidence of new AR and heart block. The authors selected patients with a “wind-sock” appearance of the aneurysm, with very specific inclusion criteria based on the geometry of the aneurysm, the details of which are beyond the scope of this chapter. The device was successfully placed in 19 of 21 selected patients, whose weights were all above 8 kg with a median age of 5 years. A recent meta-analysis of published studies comparing device closure with surgical closure of perimembranous VSDs showed comparable rates of successful closure and short-term complication rates.46 The mean age in the device group was 12.2 years, whereas that of the surgical cohort was 5.5 years. An important current limitation to the application of percutaneously placed devices is
Selected References A complete list of references is available at ExpertConsult.com. 1. Lamers WH, Wessels A, Verbeek FJ, et al. New findings concerning ventricular septation in the human heart. Implications for maldevelopment. Circulation. 1992;86(4):1194–1205. 2. Jacobs JP, Burke RP, Quintessenza JA, Mavroudis C. Congenital heart surgery nomenclature and database project: ventricular septal defect. Ann Thorac Surg. 2000;69(suppl 4):S25–S35. 12. Misra KP, Hildner FJ, Cohen LS, Narula OS, Samet P. Aneurysm of the membranous ventricular septum. A mechanism for spontaneous closure of ventricular septal defect. N Engl J Med. 1970;283(2):58–61. 13. Gabriels C, De Backer J, Pasquet A, et al. Long-term outcome of patients with perimembranous ventricular septal defect: results from the Belgian registry on adult congenital heart disease. Cardiology. 2017;136(3):147–155. 14. Abman SH, Hansmann G, Archer SL, et al. Pediatric pulmonary hypertension: guidelines from the American Heart Association and American Thoracic Society. Circulation. 2015;132(21):2037–2099. 19. Egbe AC, Poterucha JT, Dearani JA, Warnes CA. Supracristal ventricular septal defect in adults: Is it time for a paradigm shift? Int J Cardiol. 2015;198:9–14. 20. Kleinman CS, Tabibian M, Starc TJ, Hsu DT, Gersony WM. Spontaneous regression of left ventricular dilation in children with restrictive ventricular septal defects. J Pediatr. 2007;150(6):583– 586. 22. Berglund E, Johansson B, Dellborg M, et al. High incidence of infective endocarditis in adults with congenital ventricular septal defect. Heart. 2016. 26. Kanter KR, Mahle WT, Kogon BE, Kirshbom PM. What is the optimal management of infants with coarctation and ventricular septal defect? Ann Thorac Surg. 2007;84(2):612–618, discussion 618. 27. Seddio F, Reddy VM, McElhinney DB, Tworetzky W, Silverman NH, Hanley FL. Multiple ventricular septal defects: how and when should they be repaired? J Thorac Cardiovasc Surg. 1999;117(1):134–139, discussion 139–140. 28. Kitagawa T, Durham LA 3rd, Mosca RS, Bove EL. Techniques and results in the management of multiple ventricular septal defects. J Thorac Cardiovasc Surg. 1998;115(4):848–856. 30. Talwar S, Bhoje A, Airan B. A simple technique for closing multiple muscular and apical ventricular septal defects. J Card Surg. 2015;30(9):731–734. 32. Bacha EA, Cao QL, Starr JP, Waight D, Ebeid MR, Hijazi ZM. Perventricular device closure of muscular ventricular septal defects on the beating heart: technique and results. J Thorac Cardiovasc Surg. 2003;126(6):1718–1723. 33. Omelchenko A, Gorbatykh Y, Voitov A, Zaitsev G, BogachevProkophiev A, Karaskov A. Perventricular device closure of ventricular septal defects: results in patients less than 1 year of age. Interact Cardiovasc Thorac Surg. 2016;22(1):53–56.
34. Hongxin L, Wenbin G, Liang F, Zhang HZ, Zhu M, Zhang WL. Perventricular device closure of a doubly committed juxtaarterial ventricular septal defect through a left parasternal approach: midterm follow-up results. J Cardiothorac Surg. 2015;10:175. 35. Zhang S, Zhu D, An Q, Tang H, Li D, Lin K. Minimally invasive periventricular device closure of doubly committed sub-arterial ventricular septal defects: single center long-term follow-up results. J Cardiothorac Surg. 2015;10:119. 36. Pacileo G, Pisacane C, Russo MG, et al. Left ventricular mechanics after closure of ventricular septal defect: influence of size of the defect and age at surgical repair. Cardiol Young. 1998;8(3):320–328. 37. Mainwaring RD, Parise C, Wright SB, Juris AL, Achtel RA, Fallah H. Brain natriuretic peptide levels before and after ventricular septal defect repair. Ann Thorac Surg. 2007;84(6):2066–2069. 39. Anderson BR, Stevens KN, Nicolson SC, et al. Contemporary outcomes of surgical ventricular septal defect closure. J Thorac Cardiovasc Surg. 2013;145(3):641–647. 41. Preminger TJ, Sanders SP, van der Velde ME, Castaneda AR, Lock JE. “Intramural” residual interventricular defects after repair of conotruncal malformations. Circulation. 1994;89(1):236– 242.
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42. Veeram Reddy SR, Du W, Zilberman MV. Left ventricular mechanical synchrony and global systolic function in pediatric patients late after ventricular septal defect patch closure: a three-dimensional echocardiographic study. Congenit Heart Dis. 2009;4(6):454–458. 43. Holzer R, Balzer D, Cao QL, Lock K, Hijazi ZM. Amplatzer muscular ventricular septal defect I. Device closure of muscular ventricular septal defects using the Amplatzer muscular ventricular septal defect occluder: immediate and mid-term results of a U.S. registry. J Am Coll Cardiol. 2004;43(7):1257–1263. 44. Fu YC, Bass J, Amin Z, et al. Transcatheter closure of perimembranous ventricular septal defects using the new Amplatzer membranous VSD occluder: results of the U.S. phase I trial. J Am Coll Cardiol. 2006;47(2):319–325. 45. El Said HG, Bratincsak A, Gordon BM, Moore JW. Closure of perimembranous ventricular septal defects with aneurysmal tissue using the Amplazter Duct Occluder I: lessons learned and medium term follow up. Catheter Cardiovasc Interv. 2012;80(6):895–903. 46. Saurav A, Kaushik M, Mahesh Alla V, et al. Comparison of percutaneous device closure versus surgical closure of peri-membranous ventricular septal defects: A systematic review and meta-analysis. Catheter Cardiovasc Interv. 2015;86(6):1048–1056.
References 1. Lamers WH, Wessels A, Verbeek FJ, et al. New findings concerning ventricular septation in the human heart. Implications for maldevelopment. Circulation. 1992;86(4):1194–1205. 2. Jacobs JP, Burke RP, Quintessenza JA, Mavroudis C. Congenital Heart Surgery Nomenclature and Database Project: ventricular septal defect. Ann Thorac Surg. 2000;69(suppl 4):S25–S35. 3. E A. Ventricular septal defect. In: Baue AEGA, Hammond GL, et al, eds. Glenn’s Thoracic and Cardiovascular Surgery. Norwalk CT: Appleton & Lange; 1991:1007–1016. 4. Lucas RV Jr, Adams P Jr, Anderson RC, Meyne NG, Lillehei CW, Varco RL. The natural history of isolated ventricular septal defect. A serial physiologic study. Circulation. 1961;24:1372–1387. 5. Kirklin JWB-BB. Ventricular septal defect. In: Kirklin JWB-BB, ed. Cardiac Surgery. New York: Churchill Livingstone; 1993:751–764. 6. Boucek MM, Chang R, Synhorst DP. Reninangiotensin II response to the hemodynamic pathology of ovines with ventricular septal defect. Circ Res. 1989;64(3):524–531. 7. Gidding SS, Bessel M. Hemodynamic correlates of clinical severity in isolated ventricular septal defect. Pediatr Cardiol. 1993;14(3):135–139. 8. Scammell AM, Diver MJ. Plasma renin activity in infants with congenital heart disease. Arch Dis Child. 1987;62(11):1136–1138. 9. Rein JG, Freed MD, Norwood WI, Castaneda AR. Early and late results of closure of ventricular septal defect in infancy. Ann Thorac Surg. 1977;24(1):19–27. 10. Kidd L, Driscoll DJ, Gersony WM, et al. Second natural history study of congenital heart defects. Results of treatment of patients with ventricular septal defects. Circulation. 1993;87(suppl 2):I38–I51. 11. Suzuki H. Spontaneous closure of ventricular septal defects. Anatomic evidence in six adult patients. Am J Clin Pathol. 1969;52(4):391–402. 12. Misra KP, Hildner FJ, Cohen LS, Narula OS, Samet P. Aneurysm of the membranous ventricular septum. A mechanism for spontaneous closure of ventricular septal defect. N Engl J Med. 1970;283(2):58–61. 13. Gabriels C, De Backer J, Pasquet A, et al. Long-term outcome of patients with perimembranous ventricular septal defect: results from the belgian registry on adult congenital heart disease. Cardiology. 2017;136(3):147–155. 14. Abman SH, Hansmann G, Archer SL, et al. Pediatric pulmonary hypertension: guidelines from the american heart association and american thoracic society. Circulation. 2015;132(21):2037–2099. 15. Yamaki S, Mohri H, Haneda K, Endo M, Akimoto H. Indications for surgery based on lung biopsy in cases of ventricular septal defect and/or patent ductus arteriosus
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