Percutaneous therapy of structural heart disease: Pediatric disease

Percutaneous Therapy of Structural Heart Disease: Pediatric Disease Rajiv Verma and John E Keane

Interventional therapy of congenital heart lesions at cardiac catheterization has greatly increased during the past decade. At the authors' institution, the frequency of such procedures among Catheterizations has increased from 5% to more than 60%. The variety of lesions so treated continues to expand and equipment continues to improve. These procedures may be divided into 2 groups, namely {1) those involving balloon dilation of stenotic valves and vessel obstructions with stent placemen t being increasingly used in the latter and (2) those involving occlusion of lesions with (a) coils, such as aortopulmonary collaterals, patent ductus artedosi and coronary artery fistulae and (b) umbrella devices, such as atrial and ventricular septal defectS. These have replaced surgery as the initial procedure of choice in many lesions including valvar pulmonary and aortic stenoses, and postoperative aortic coarctation in young patients. In addition, use of the doubleumbrella device even n noncongenital lesions appears promising. Copyright © 1997 by W.B. Saunders Company

'nterventional therapy in congenital heart disthe introduction of balloon atrial septostomy for transposition of the great arteries by Rashkind and Miller in 1966.1 a procedure still extensively used. This was followed about 16 years later by the report of Kan et al, 2 in which static balloon dilation of a stenotic pulmonary valve was described Since then. this field has literally "exploded" (as may be seen in Fig 1, from the authors' institution) with interventional procedures increasing over 10 years from initially approximately 5% in some 600 catheterizations to more than 60% in more than 1,000 procedures. The variety of lesions so treated has greatly expanded, and in many patients is part of a combined approach with the authors' cardiac surgical colleagues: for example, closing aortopul-

l .ease really began with

monary collaterals in patients with tetralogy of Fallot before or after surgical repair. These advances have dramatically changed the catheterization laboratory mission, initially charged with acquisition of physiological and anatomic data only, to now including a large therapeutic facet. This has resulted in significant personnel changes. There has been an increase in the number of dedicated technicians and nurses and in the invaluable contributions of the authors' colleagues in echocardiography and anesthesia; for example, approximately 10% of patients now require general anesthesia for these procedures. In addition, equipment inventory has mushroomed, as exemplified by more than 100 different types of balloon dilation catheters now being available. For the adult cardiologist, these changes have increasing importance. In the US, it is estimated that some 37,000 newborns per year have Some form of congenital heart disease. Our own recent 17 year survival, which includes all forms of heart defects, is some 84%. Using these numbei:s, about 31,000 patients each year with congenital heart disease survive to this age. If one applies lesion occurrence frequencies to this group, one may speculate that approximately 2,500 patients with tetralogy of Fallot, a similar number With valvar aortic stenosis, 3,100 with valvar pulmonary stenosis and 1,500 patients with transposition attain age 17 every year, Paral!elling these observations, compared with 20 years ago, the number of adult patients catheterized by the authors has From the New York University Medical Center, Cardiac Catheterization Laboratory, New York, NY, and Harvard Medical School, Department of Cardiology, Boston, MA. Address reprint requests to John F. Keane, MD, Children's Hospital, Department of Cardiology, 300 Longwood Avenue, Boston, MA 02115. Copyright © 1997 by W.B. Saunders Company 0033-0620/97/4001-000455.00/0

Progress in Cardiovascular Diseases. Vol. 40, No. 1 (July/August), 1997: pp 37-54

37

38

VERMAAND KEANE 1500

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Total

Number

1

T A B L E 1. Interventional Features Reflecting the Practice and E x p e r i e n c e at Children's Hospital

- -

.~ 1ooo "~ d

Balloon Dilation Stenotic Valves Pulmonary Aortic Mitral Tricuspid Stenotic Vessels Pulmonary arteries Aortic coarctation Stent Placement Lesion Occlusioti Coils Aorto pulmonary (A-P) collaterals Patent ductus arteriosus (PDA) Coronary ai'tery fistula Shunts Venous collaterals Double Umbrella Devices Atrial septal defect (ASD) Patent Foramen ovale (PFO) Fenestrated Fontan pathway (FF) Ventricular septal defect (VSD) Patent ductus arteri0sus (PDA)

!iii!iiiii)ii ~iriii!i!i!!!i~ 500

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'84 '85 '86 '87 '88 '89 '90 '91 '92 '93 Year Fig 1. Dramatic increase in number of interventional procedures during 1e-year period.

more than tripled (Fig 2), with interventional procedures being now undertaken in 50% of these. These interventional procedures, excluding ablation of arrhythmias, are presented in Table 1 and largely reflect the authors' practice and experience at Children's Hospital.

Technique

Balloon Dilation stenotic Valves Pulmonary valve stenosis. Balloon dilation has become the accepted standard treatment for simple valvar pulmonary stenosis in the older child and also at many institutions for the neonate with critical obstruction. The use of oversized balloons (120% to 140% annulus diameter) has been shown to be safe and improve gradient reduction. 3

Age (yr) 21 30 40 50 60 70 80

29 39 49 59 69 79 +

Cath # (CH, Boston) 1970-75 1990-95 91 19 0 2 0 0 0

227 118 51 22 21 25 1

112

465

Fig 2. Dramatic increase in numbers of adult patients seen with congenital heart disease between 1970 to 1975, and 1990 to 1995.

From a femoral venous approach, the dilating balloon is placed over a wire to straddle the valve (Fig 3) whose diameter has previously been measured from the lateral view of a right ventricular cineangiogram. In patients with a valve annulus exceeding 20 mm in diameter, two balloons (Fig 4) are simultaneously inflated? In the neonate, the procedure, more technically demanding, occasionally may be accomplished via the umbilical vein. In these infants, the 0.018 torque guide wire frequently crosses the patent ductus to the descending aorta affording a more direct and stable route; balloon lengths should not exceed 2 cm and smaller diameter balloons are frequently initially used.

Results Beyond the neonatal period, immediate and late results have been gratifying. In the authors' early experience5 in 54 patients with Simple valvar stenosis, the initial peak systolic ejection gradient of 74 + 16 mm Hg was reduced to 15 + 18. The final gradient was unrelated tO initial gradient magnitude and residual infundibular obstruction resolved within a year in many patients. In addition, the authors' results in postoperative patients have been comparable. At this time, in a

CATHETERIZATION THERAPY IN CONGENITAL HEART DISEASE

39

Fig 3. Balloon inflating across stenotic pulmonary valve with waist (A) and waist abolished: lateral view (B).

total of 295 patients dilated beyond 1 month of age such results have continued. In those few with unsatisfactory gradient reduction, valves have been dysplastic or annuli hypoplastic and surgery has been necessary. Similar results have also been reported by many others including the large population in the congenital anomalies registry report. 6 Complications have been few, mostly minor, and while pulmonary regurgitation has been noted in some, this is well tolerated. In the authors' early neonatal experience of 36 babies, 6 94% were successfully dilated and right ventricular/systemic pressure ratio decreased from 150 - 32 to 83 ± 30%. At 33 ± 23 months of follow-up, among 31 managed by dilation alone, all were well, 90% had echocardiographic instantaneous gradients <30 mm Hg and 52% had pulmonary regurgitation, mild in most. At this

time, a total of 60 neonates have been so treated, with two early postcatheterization deaths due to necrotizing enterocolitis and one due to endocarditis which was medically managed. Redilation was carried out in nine patients (16%); it was successful in five, whereas the other four underwent surgery. Thus, the authors recommend balloon dilation in (1) neonates with critical obstruction and in (2) older patients with simple valvar stenosis, including postoperative patients without significant regurgitation with an instantaneous gradient >40 mm Hg. Aortic valve stenosis. Balloon dilation for valvar aortic stenosis, in a child, was first reported by Lababidi in 1983. 8 Studies shortly thereafter in lambs with normal valves revealed that a balloon annulus ratio ->120% resulted in significant val-

Fig 4. Double balloon inflation across stenotic pulmonary valve (A) with waist and (B) waist abolished: AP view.

40

VERMA

AND

KEANE

Fig 6. Antegrade transseptal course of wire and balloon ( I V C - ~ R A ~ R A ~ L A ~ L V ~ A o ) in vaivar aortic stenosis.

Fig 5. Waist on balloon produced by stenotic aortic valve during inflation: lateral view,

var and surrounding structure damage. 9 In a recent intraoperative study using a ratio -> 100%, dilation effects were directly visualized. A tear in leaflet tissue anteriorly was seen in some 30%. l° Nevertheless, this catheterization laboratory technique (in which the initial ratio is 90%) is dramatically effective in the great majority of young patients with pliant valves and has become the standard modality of treatment, even in neonates with critical obstruction, and in postoperative valvotomy patients in most centers. The indications for treatment, beyond early infancy, are a peak systolic ejection gradient >50 mm Hg with no greater than mild aortic regurgitation at catheterization.

Technique Beyond infancy, virtually all procedures are performed retrograde using a femoral approach. Two arterial catheters are used to accurately measure gradients and evaluate aortic regurgitation. The initial balloon size is --<90% of the annular diameter measurement. Preformed stiff Amplatz guide wires and appropriately long balloons are used for stability during inflation (Fig 5). Cardiac output, gradient and aortic regurgitation are assessed

after each inflation. In the neonate, often ill and intubated, the procedure may be more demanding; the femoral retrograde approach is frequently used, but use of the umbilical artery is feasible in many, and use of the antegrade transeptal approach is now used when possible (Fig 6).

Results Immediate gradient reduction is at least 50% regardless of age, with the absolute residual value in the great majority being less than 40 mm Hg (Fig 7), comparable to the results in many other series. Among 148 patients over age 1 month, gradient reduction was 56.4 -+ 19.9% and freedom from surgery at 4 years was 75%. Significant 40

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Age

Fig 7. Median immediate postdilation (BD) peak systolic ejection gradients (PSEG) in valvar aortic stenosis by age: all less than 40 mm Hg: all >50% gradient reduction,

41

CATHETERIZATION THERAPY IN CONGENITAL HEART DISEASE

Mitral Valve Damage

120 g.D,

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mild

mild

mod

mod

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10y

11y

17

19y

20y

6wks. 4y

mod

Age Fig 8. Peak systolic ejection gradient (PSEG) and aortic regurgitation (AR) data in patient with valvar aortic stenosis had surgical vaivotomy at age 6 weeks recurrent obstruction at 10 years, dilated: now 10 years later (4 caths) PSEG stable (50 mm Hg, AR mod).

aortic regurgitation was present initially in 13.2% but had however progressed to 38.2% at an average follow-up of almost 4 years, n The authors' results in a group of young adults were comparable. 12 Pulse loss has been less than 1% in the older patients. In the authors' first 46 neonates so treated, among 33 with adequate left heart structures procedure-related mortality was 9% and survival at a mean follow-up of 4.3 years was 88% with pulse loss being 67% in those dilated via a femoral artery. The average gradient reduction initially was 42%, and significant regurgitation was noted in 9%. None of the 13 babies with hypoplastic left heart features were "2ventricle" survivors. 13

Among more than 200 patients to date, mitral valve damage has occurred in three; in two art antegrade approach was used and is an avoidable complication in the authors' opinion. In all three, the anterior leaflet had been split, and was successfully repaired at surgery (at which time the aortic valve dilation was noted to have been adequate).

Aortic Regurgitation Postdilation Among 25 of the authors' patients operated on for regurgitation (age 1 to 31 years), plication of the torn leaflet and valvotomy have been feasible in eight without further surgery to date, similar to the experience of others. 14 The authors recommend dilation (1) for a peak systolic gradient of > 5 0 m m Hg, with mild regurgitation at most in children who are beyond infancy (including postoperative patients) and (2) in neonates with significant left ventricular dysfunction, regardless of gradient magnitude. In patients with significant regurgitation post dilation, surgical valvuloplasty of a tear which can be recognized should be considered. Congenital mitral stenosis. Since the initial reports of balloon dilation of rheumatic mitral stenosis, 15,~6 this procedure is now used worldwide. It has also been used at some centers in congenital mitral obstruction, a rare lesion which is a difficult surgical problem. Congenital mitral stenosis is associated with other cardiac lesions in 96% of patients, including some form of left ventricular outflow obstruction in 55%, coarcta-

Features of Interest 100

Dilation Postoperatively The authors have now dilated valves after a prior surgical valvotomy in 29 patients (age 0.3-29 yrs, av 9 yrs) without mortality. The average gradient reduction was 48% and significant regurgitation was 34%, representing an increase in 21%. (Fig 8).

75 I E E 50 (.9

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Repeat Dilation This has now been performed in 33 patients, six of whom have had a third dilation (Fig 9) and one a fourth, without mortality. The initial dilation was performed in the neonatal period in 15 of these. The average gradient reduction was 44% and significant regurgitation occurred in 15%.

a. 25

~e

No AR

No AR

mild AR

4Y BD1

8Y BD2

<11Y BD3

Fig 9. Catheterization data from three dilations for recurrent obstruction over 7 years in unoperated valvar aortic stenosis (VAS).

42

VERMAAND KEANE

Results

Fig 10, Balloon during inflation across stenotic mitral valve with "waist" (arrow) eliminated,

tion in 40%, ventricular septal defect in 25% and an atrial defect in a similar number. The mitral anatomical deformity in these patients is quite variable, consisting of a hypoplastic annulus, thickened leaflets and short chordae in 60% an associated supravalvar ring in 20% a double mitral orifice in 11% and a parachute arrangement in 9%. 17 Not surprisingly, given this wide morphological variation, dilation results are variable.

In the authors' experience with 18 patients who underwent 29 dilations, the average atrial A-end diastolic gradient reduction was 55% (Fig 11). At least moderate regurgitation occurred in 16% and two infants died. Symptomatic improvement at 24 months persisted in 45% of infants and 75% of children, although restenosis occurred in 20% by 8 months. 17 In terms of morphology, significant regurgitation occurred in all with a supravalvar mitral ring, with best results being obtained in those with a double mitral orifice. Therefore, the authors recommend dilation of significant congenital mitral stenosis except in those with a supravalvar ring. Tricuspid stenosis. During the past decade, this has been encountered rarely and balloon dilation has been attempted only in 12 patients. This lesion occurred exclusively in association with other intracardiac defects, mostly right sided. Among 10 of these patients, all with intact ventricular septa, five had had transannular outflow patches for pulmonary atresia, two had critical valvar pulmonary stenosis dilated at the

20mmHg

Technique Using a transseptal and retrograde arterial approach, the transmittal gradient is measured, together with cardiac output and regurgitation (if any). A preformed wire is advanced to the left ventricular apex and a balloon, initally 2 mm less than the echocardiographic annular measurement, inflated (Fig 10). It may be necessary in older patients to use a double-balloon technique. Hemodynamic measurements are repeated and, if necessary, larger balloons are used until the gradient is satisfactorily reduced or significant regurgitation induced. Anesthesia support is necessary in the very young because of considerable hemodynamic instability.

Pre Dilation

Post Dilation

Fig 11. Reduction of gradient (shaded areas) across stenotic mitral valve (congenital) by balloon dilation,

CATHETERIZATION THERAPY IN CONGENITAL HEART DISEASE

same procedure, one had a large atrial defect, another had Ebstein's anomaly, and one had mitral stenosis. The remaining two patients, who were the oldest at 19 and 20 years, had previously placed porcine valves for regurgitation.

Technique The valves were dilated initially with balloons 2 mm less than the annular diameter, the transvalvar gradient was remeasured and valve competency was assessed. Progressively larger balloons were used if gradient reduction was unsatisfactory and regurgitation was not significant.

Results

43

infancy and results seem better than at an older age. It should be avoided for at least i month after surgery to negate the risk of local suture line dehiscence. The number of patients with primary diffuse peripheral pulmonary stenosis treated in this manner is increasing as resultS with the use of high pressure balloons improve. Many lesions may be dilated during the Same procedure, Usually beginning with the most severe. Great Care should be taken to avoid recrossing dilated areas, using the softest of torque wires if this should be necessa W. The addition of stents to the armementarium has greatly increased the success rate.

Technique

Despite a variety of morphologies, a gradient reduction of >-33% was accomplished in 45%, ->50% in 27%. Regurgitation increased in 33% of the congenital group; no patient developed > mild regurgitation. Gradient reduction (37%) was obtained in only one of the two patients with porcine valves. Thus balloon dilation for tricuspid stenosis was effective in only one-quarter of the patients.

After angiographic delineation using a cut off ultra thin-walled pigtail over a distally placed guide wire and a pressure withdrawal recording, an appropriate balloon is chosen (usually with a diameter 3 × the stenotic site value and less than 2 × the diameter of the distal vessel) and inflated. A pressure withdrawal and angiography are repeated and progressively larger balloons are used if necessaw. 21 Lung perfusion scans are obtained before and after the procedure to assess results.

Stenotic Vessels

Results

Successful balloon angioplasty of experimentally produced stenotic lesions in pulmonary arteries and aortas results from tears produced in the intimal and medial layers with subsequent remodeling. 18,19 The balloon technique has since been applied in large numbers of patients with considerable s u c c e s s , 15,2° aided by the continuing development of high pressure low profile balloon catheters which require use of a mechanical inflator. More care and vigilance is required when using these balloons as they are more likely to tear lesions and produce aneurysms as compared with their low pressure polyethylene predecessors. Pulmonary arteries. Dilation of pulmonary arteries is the most common interventional procedure undertaken at the authors' institution, with 689 patients having u n d e r g o n e this maneuver during the past decade. These lesions may be single or multiple, congenital or acquired (the latter often after surgery). The most commonly associated congenital heart disease is tetralogy Of Fallot. Although dilation can be performed at any age, elective procedures are performed between 2 to 4 years of age as it is less hazardous than in

A procedure is considered successful if the diameter of the stenosis is increased >50% or flow is increased, or both. Using these criteria, the success rate in the authors' earlier Series5 was 55% (Fig 12). With the advent of high pressure balloons, this has increased to 72%. There have been four deaths in the entire series due to vessel rupture; distal aneurysms are not uncommon and have been without sequelae; pulmonary edema distal to the dilated lesion has occurred in a few and has been managed medically. Coarctation of the aorta. Balloon dilation of coarctati0n was first described in 198222 and has since become the standard method of managment for postoperative lesions. It is also being increasingly used in native coarctation beyond the neonatal period in marly centers with satisfactory results and without significant aneurysm o c c u r r e n c e . 6,23,26,27 At the present time, the authors continue to use this modality of management for all types of postoperative aortic obstructions regardless of age and in selected nonoperated patients, believing that results by experienced surgeons in native coarctations are better. The

44

VERMA AND KEANE

Fig 12. Stenosis LPA origin (A) and successful balloon dilation (B) lateral view.

authors believe that recently reported echocardiographic observations will aid considerably in choosing appropriate native coarctations for dilation. 24

Technique Following standard right and left heart catheterization, a balloon with a diameter 3 × the coarctation diameter but not exceeding by 50% the proximal or distal aorti c diameter is rapidly inflated over the guide wire to abolish the "waist"~, it is then rapidly deflated. While maintaining position of the preformed guide wire in the ascending aorta, residual gradient measui:ement and angiograpy are performed. Other types of obstructions so treated include interrupted arch residual obstructions and post stage 1 hypoplastic left heart lesions, the latter approached using an antegrade venous route. 24

Results Gradient reduction in postoperative obstructions, regardless of the method of surgical repair, is satisfactory at approximately 70% 6,21 and persists during follow-up (Fig 13). Among the authors'

Fig 13. Successful balloon dilation of postoperative aortic coarctation: pre (A) and postdilation 5 years later, lateral view (B).

205 patients so treated to date, there have been two procedure-related deaths, one in an infant with hypoplastic left heart syndrom e and the other presumably arrhythmia related. The most frequent complication has been transient pulse

lOSS. In one institution's large native coarctation dilation series with 3 years follow-up, 26,2r among 102 patients dilated (average age 4.6 years) with a discrete lesion, 71% were normotensive with gradients all -<20 mm Hg. A repeat dilation was undertaken in 18 (22.8%), 17 of whom were normotensive more than 6 years later. A repeat dilation or operation was necessary in 10 of 13 neonates. The Overall aneurysm incidence was 1.9%. Among the authors' small native coarctation dilation group the only complication encountered was an aortic dissection, successfully surgically repaired, in a 67-year-old Woman in whom a 12-mm balloon had been used to dilate a 5-mm diameter obstruction.

Stent P l a c e m e n t Balloon expandable intravascular stems have been successfully used to enlarge lumens in the periph-

45

CATHETERIZATION THERAPY IN CONGENITAL HEART DISEASE

eral and coronary circulations of adults for a decade. The results of application of this technology in experimental animal pulmonary arterial and systemic venous obstructions by several investigators were encouraging. 2s,29 Subsequently, together with equipment improvements this has resulted in increasing stent use in the management of obstructed vessels, particularly pulmonary arteries in children and young aduhs. 3°-32A pulmonary artery location has been the authors' most frequent site of stent placement, this being carried out in 219 patients to date. Other sites of obstruction so managed, albeit in considerably smaller numbers to date include superior vena cava-right atrial (SVC-RA) junction, rightsided venous pathways in postoperative Fontan patients, right ventricular-pulmonary artery homografts, 33,34 pulmonary veins, complex subvalvar left ventricular outflow tract and various aortic locations. The most commonly used variety is the Palmaz stent (Johnson and Johnson International Systems, Sommerville, NJ) a cylindrical meshwork of tempered steel available in lengths of 10 to 30 mm and expandable to 20 mm. Delivery requires an 8F long sheath for the smaller profile (2.5 mm) biliary stent (lengths 10, 15, 20 mm) and an l l F long sheath for the larger profile (3.4 mm) iliac stent (lengths 12, 18, 30 mm). The smaller one may be dilated to 12 mm and the larger to 18 mm in diameter. Although sheath size precludes use in neonates, the smaller 8F sheath can be used in infants weighing as little as 6 kg. Concerns related to development of relative stenosis at the site of stent implantation as patients grow have been raised. Recently, however, investigators have shown that stents can be safely reexpanded in both animals and some patients, typically 1 year later. 34-37 It has also been shown in animals that stents do not significantly interfere with growth of normal surrounding tissue and that complete endothelialization occurred within 3 months of implantation. 36 When stents have been used as a palliative bridge to future surgical correction of underlying congenital heart disease, it is of interest that their removal at surgery has not posed any significant problems. They are currently being successfully used to enable staged rehabi.litation of diminutive pulmonary arteries in infants and children with tetralogy of Fallot before repair , a condition once considered inoperable. Although implantation in arteries and veins has not been

associated with stent fracture, this has occurred in some placed in RV-PA conduits. 31,3z'34

Technique Right and left heart catheterization is performed to assess hemodynamics and evaluate the cardiac and vascular anatomy precisely. Once a diagnosis of significant obstruction is confirmed, balloon angioplasty is performed initially. Several purposes are served by balloon angioplasty immediately before stent implantation. If the dilation is successful, stent implantation can be avoided. It allows one to determine if the lesion is balloon expandable and allows for use of high pressure balloons to dilate the lesion before stent implantation with low pressure balloons. Finally, one can determine if and how the balloon moves during inflation so that the stent can be appropriately positioned. This is of considerable importance in RV-PA conduits and aortic locations; as these are the sole routes of blood flow, balloon movement is magnified. In RV-PA homografts, it is important to remember that most Of these are calcified and in addition to calcium fracture, puncture of the balloon is common. Intubation and general anesthesia are not used routinely but are necessary if significant hemodynamic compromise is present or anticipated. Vascular access for implantation varies depending on the location of the lesion to be stented, the aim being to achieve the straightest and most direct course to the stenotic area to minimize stent dislodgment from the balloon catheter. Patients are anticoagulated with 100 units/kg of heparin and the activated clotting time is kept above 200 seconds during the entire procedure to prevent thrombosis due to the manipulation of multiple catheters and guide wires. Cefazolin 25 mg/kg is administered initially arid subsequently every 6 hours for a total of three doses. The Palmaz stents most commonly used in patients with congenital heart disease are shown in Table 2.

TABLE 2. Palmaz Stents Most Commonly Used in Patients With Congenital Heart Disease Diameter (mm)

Bilary stents Iliac stents

Unexpanded

Expanded

Lengths (mm)

2.5 3.4

12 18

10, 15, 20 12, 18, 30

46

VERMA AND KEANE

stenoses of pulmonary arteries (eg, in tetralogy of Fallot postoperatively) bilateral stents may be placed during the same procedure.

Results

Fig 14. Increase, (lateral view) in diameter of obstructed RV-PA homograft pre and poststent placement.

In choosing a stent, the diameter and length must be considered. For lesions larger than 12 mm in diameter, an iliac stent is used. The length is chosen to be long enough to span the lesion but short enough to avoid surrounding structures such as side branches or valves. Because shortening of Palmaz stents occurs as they are expanded, the degree of shortening must be calculated before insertion. T h e balloon mounted stent is advanced to the stenotic lesion over a stiff guidewire, through an approximately sized long sheath. Side arm adapters are used both to prevent bleeding and allow contrast injections through the sheath. Stiff exchange wires make it easier to position these long sheaths and stabilize the balloon and stent during imPlantation. After initial placement and dilation, it is common to use a larger balloon both to increase the diameter and to further flare both ends of the stent. Anticoagulant therapy is maintained subsequently for a period of 6 months. Lung perfusion scans are obtained before and after implantation in pulmonary arteries. In patients with bilateral

Relief of obstructive lesions in branch pulmonary arteries, right ventricular outflow tract (Fig 14), systemic venous systems, and Fontan pathways (Fig 15) has been very satisfactory on short and intermediate-term follow up to date. 31 In the latter large series, it is important to note that after pulmonary artery stent implantation, no aneurysm formation or significant restenosis at the stent site occurred. The mean pressure gradient decreased from 55 to 14 mm Hg and the diameter increased from 4.6 to 11.3 mm. In some patients,' the branch pulmonary artery size was almost normal for age. Relief of right sided venous channel obstruction by stent implantation is extremely promising (Fig 16), which is especially important in light of the less than satisfactory intermediate or long-term results obtained by balloon angioplasty alone. In the authors' own recent experience with 48 patients who underwent stent placement in RV-PA conduits 34 at a median age 6.9 years, the gradient initially decreased from 60 to 30 mm Hg. During a median follow-up of 14 months, stem fracture was noted in seven patients and recurrent obstruction due to external compression occurred in all 16 restudied, despite sustained enlargement at the previously stented site. Nevertheless. actuarial freedom from conduit reoperation was 65% at 30 months. In coarctation of the aorta in animal studies 3s as well as in a small pauent series 39 stent placement was shown to be effective. In the authors' experience to date of approximately 27 patients, prelimi-

Fig 15. Increase in both atrial channel and left pulmonary artery dimensions before (A) and (B) after balloon dilation and stent placement in patient postmodified Fontan operation.

CATHETERIZATIONTHERAPY IN CONGENITALHEART DISEASE

47

nary results are encouraging (Fig 17). In contrast, recurrent obstruction or even occlusion has been common with stents placed in pulmonary veins, although satisfactory patency has been maintained in those placed in systemic venous channels such as the SVC-RA junction. Stent placement in stenotic pulmonary arteries is very satisfactory and safe, and in obstructed RV-PA conduits allows postponement of surgical replacement in most patients for several years.

Lesion Occlusion Coils Coils have been used to occlude "unwanted vessels" in congenital heart disease for more than 2 decades. 4°-4s The list of lesions so treated is long, continues to expand and includes aortopulmonary collaterals, rightsided venous channels shunting to the lower pressured left atrium after Fontan type operations, unwanted surgically placed shunts and coronary artery fistulae. In addition, in recent years the patent ductus arteriosus, in rapidly increasing numbers, has been added to the list. 49-58 The most commonly used device is the Gianturco (Cook; Bloomington, IN) stainless steel spring coil with Dacron strands (the latter absent in the last few mm of the coil presumably to prevent entanglement by the delivery wire). They are available in 0.025", 0.035", 0.038" size in a very wide variety of diameters and lengths. The 0.038" is the most "robust" and is the easiest to see on the fluoroscopic screen (both are desirable properties). Also available are the more expensive Tracker systems (0.025" and 0.035" sizes) which are of particular value in tortuous channels,

Fig 17. Severely stenosed abdominal aorta in patient with Williams syndrome (A) and enlarged lumen following stent placement (B).

especially in some coronary artery fistulae. Excellent imaging capabilities are necessary to deploy these safely. Retrieval devices such as snares and baskets should be on hand to retrieve the inevitable errant coil. The smaller Gianturco coils are usually delivered through a 4F catheter and the largest is delivered (0.038") via a 5F catheter. These delivery catheters include Cobra (Medi-

Fig 16. Severe stenosis of SVC-RA junction, lumen occluded by catheter, (A), balloon inflated in SVC-RA junction, (B), and lilac stent dilated to 18 mm in SVC-RA junction (C).

48 Tech, Watertown, MA), Berenstein (MediTech), and rightJudkins (Cook; Bloomington, IN) coronary configurations.

Technique In aortopulmonary (A-P) collaterals, PDA, coronary artery fistulae, and Blalock-Taussig (classical and modified) shunts, coils are usually delivered via a retrograde arterial approach. In A-P collaterals, one first has to ensure that the lung segment supplied by the vessel has alternate connections with the native pulmonary arteries. T h e A-P vessel is usually long with a stenotic site at its distal end. Because the vessel is somewhat disterlsable, a coil 120% of the vessel diameter is first placed just proximal to the stenosis. If occlusion is incomplete, other smaller coils are added within its lumen. In the PDA, the first loop of the coil is placed on the pulmonary artery side and the remainder (the coil diameter being 2 to 2.5 times the narrowest site) delivered on the aortic side. If significant flow persists, one or more additional coils are placed. The final coil position should be such that one loop is on the "PP2'side and three to four loops on the "aortic" side (Fig 18). Placement of an extruded coil externally on the left lateral chest wall during the angiogram is of value in choosing the diameter necessary. The number of loops (N) in a coil may be precalculated using the formula N = L/'rrD in which L = length and D = diameter. In coronary artery fistulae, those which are best suited for coil occlusion are those with a single stenotic entry site into a right heart chamber with no branches arising from the immediately proxi-

VERMA AND KEANE

mal 1 to 2 cm. The latter is best shown by injecting contrast via a temporarily occluding balloon end hole catheter a few centimeters proximal to the fistula site. While the usual delivery catheters may reach the desired coil deposition site over a torque wire, the Tracker 0.035" system is excellent for this purpose. Coils are then placed until the fistula is occluded (Fig 19). In closing Blalock-Taussig shunts, 44 especially the modified variety which do not have stenosis at the PA entry site, a transvenously placed balloon is first inflated to occlude the PA and shunt orifice and coils (often two) are then delivered into the shunt lumen (Fig 20). The coil diameter should be just larger then the shunt lumen, the latter usually a little smaller than at the time of placement. In venous channels, shunting right to left with resultant systemic desaturation, coils are placed via an antegrade venous approach. Because veins are more distensable than arteries, coil diameter should be 140% of the vessel lumen initially. If closure does not result, smaller coils are then packed into the larger coil.

Results Occlusion of A-P 44 and systemic venous collaterals is very effective; in the former, coil placement may be very difficult when the vessel is short. Nevertheless, coil loops protruding into the aortic lumen have not been associated with complications and are covered with erldothelium within months. 53 Coil occlusion of the PDA is very promising. In these vessels, almost all less than 4 mm in

Fig 18. PDA pre coil placement (A) and occlusion of PDA by coils: lateral view (B).

49

CATHETERIZATION THERAPY IN CONGENITAL HEART DISEASE

AP

LAT

Pre

Post

Fig 19. Coronary artery fistulae from circumflex to right atrium (pre) and following coil occlusion (post): AP and LAT views.

diameter, occlusion rates at follow-up have ranged from 93% to 94%, using one or more coils. Embolization to a pulmonary artery has occurred in a few during the procedure with retrieval accomplished in m o s t . 49-52 Modifications of technique using snares 52 and detachable coils will likely improve results and decrease embolization. In the authors' earlier series of nine patients' coronary artery fistulae, 46 all were completely closed, using Gianturco coils in six, and a 12-mm Rashkind double umbrella device in the other

three. These closure results have been maintained in 22 patients to date. The authors recommend coil occlusion for A-P and venous collaterals, PDA with a diameter -<4 m m in patients older than 6 months, Blalock-Taussig shunts and selected coronary artery fistulae.

D o u b l e Umbrella Devices In 1976, transcatheter closure of atrial septal defects was reported by King and Mills54; three

Fig 20. Left modified Blalock Taussig shunt (A) and shunt occluded by coils (B).

Pre

Post

50

VERMA AND KEANE

Fig 21. PDA (A), 12 mm Rashkind device placed in PDA (B), and occlusion of PDA by device: lateral view (C).

years later, Rashkind and Cuaso described closure of patent ductus arteriousus using a double umbrella device. 5s Subsequently, a number of investigators reported their experience with this device° available in 12 mm and 17 mm diameters and delivered via 8F and 11F sheaths respectively. One series using this approach enrolled 182 patients. 56 Closure rates have been approximately 80%, with better results being achieved with the smaller umbrella. Lesions managed with this device include large venous channels, congenital interatrial defects, unusual aortopulmonary shunts and ventricular septal defects. 57,58This device was then redesigned in a clamshell configuration with subsequent successful evaluation in the atrial septa of animals, s9 After this report, clinical trials began with devices being placed in a wide variety of lesions including atrial septal defect (ASD), 6° patent foramen ovale (PFO) 61 fenestration in a Fontan (FF) pathway,62 ventricular septal defect (VSD) both congenital and postmyocardial infarction 58,63 and patent ductus arteriosus (PDA). During this experience, it became clear that echocardiography particularly transesophageal, was invaluable in assisting accurate placement in

septal defects. 65 Use of a buttoned device in ASD and PDA has also been reported by other investigators. 66-69 The following data represent some of the authors' experience with use of the Rashkind device (primarily in PDA [198 patients]) and the original Bard Clamshell occluder in a wide variety of lesions (475 patients).7°

Technique All patients initially undergo complete right and left catheterization with accurate angiographic delineation of the lesion proposed for closure. General anesthesia including intubation is used in ill patients and particularly in those with VSD, with transesophageaI echocardiography being invariably used in the latter. Balloon sizing to determine the size of the device to be implanted is routinely performed in atrial and ventricular defects. Both devices are delivered via a transvenous approach.

Rashkind device These are of two sizes, namely (1) 12 mm without platinum on the proximal three arm tips and

Fig 22. Balloon sizing of ASD (A), device (arrow) released in ASD (B), and right atrial cineangiogram (RA) with all distal 4 arms of device appropriately located on left atrial side (arrow), without residual shunt (C).

51

CATHETERIZATION THERAPY IN CONGENITALHEART DISEASE

Fig 23. Congenital VSD (A) and ClOsure following clamshell device placement (B).

delivered via an 8F sheath and used in a PDA <3 mm diameter (Fig 21), and (2) 17 mm, delivered via an 11F sheath for the larger PDA. After device placement, if residual shunting persists, balloon pressure against the proximal arms may be effective. If not, closure at a later date, usually with coils is invariably successful.

Clamshell Device The original Bard Clamshell device was available in five sizes, ranging from 17 to 40 mm in diameter and all delivered via an 1IF sheath. The device diameter used is at least twice that of the balloon--sized value in ASD (Fig 22) and VSD (Fig 23) and 17 mm for Fontan baffle fenestration closure (Fig 24). In VSD, the venous approach route depends on the location of the defect, the IVC-RV-LV course being used for those located in the anterior muscular septum with a jugular (SVC-RV-LV) approach often for those located at the apex. Midmuscular and a few apical defects are generally closed via the mitral valve from an IVC-LA (transseptal)-LV approach. Membranous and inlet VSD are not managed with devices due to proximity of valvar structures. If there are

multiple muscular ventricular defects, it is usually necessary to place more than one device during the same procedure (Fig 25).

Results Rashkind (12 mm, 17 mm) devices: In the authors' 170 patients with follow-up information with PDA, complete closure was accomplished in 84.7% and partial closure in 15.3%, compared with 78% complete closure at 8 months in another large series reported.56 Closure was more frequent in smaller lesions with the smaller device.

Original Bard Clamshell (17 ram-40 ram) Devices Among the authors' 475 patients who had devices placed, only 45% were considered to have simple defects (ASD, PFO, PDA)--the remaining 55% were deemed high-risk surgical candidates. Acceptable closure (that is complete closure or at most a small residual flow) rates at an average follow-up of 33 months were 89% ASD, 94% postoperative ASD, 98% PFO, 99% Fontan fenestration, 100% PDA, and 81% VSD, including the

Fig 24. Fenestration in Fontan atrial baffle with right!eft shunting of contrast (A) and occlusion of fenestration by 17 mm Clamshell device (B).

52

VERMA AND KEANE

Fig 25. MUltiple (5) devices placed in muscular VSDs, (A) AP view, (B) LAT view.

postmyocardial infarction group. 7° Closure rates reported by others using the buttoned device for ASD closure were 55% to 98% 66,67 and 75% in defects ->23 mm diameter, in the latter using a device 45 mm to 60 mm in diameter. 69 Virtually all the authors' ASD defects were less than this size. Device arm fracture occurred in 118 patients (25%) and was most frequent with the larger devices in the ASD position with late complications (definitely or possibly) occurring in seven of these patients: The device has since been redesigned to eliminate this problem, with clinical trials about to begin. Arm fracture has not been observed with the buttoned device in the series reviewed. There was one death in our series, in an elderly patient, related to a stroke which occurred before device placement. TABLE 3. Bard Clamshell Occluder to Date Selected Lesions

Lesion

N

Effective Closure (%)

Device Arm Fracture (%)

ASD PFO VSD (congenital) (pre/postop) VSD (post MI) PDA

43 43 6

81 98 100

69 48 0

12 8

33 100

100 0

NOTE. Adult (age >-21 years). Abbreviations: N, number of patients; ASD, atrial septal defect; PFO, pate nt foramen ovale; VSD, ventdcular septal defect; pre/post op, pre or postoperative; post MI, post myocardial infarction; PDA, patent ductus arteriosus.

Adult Patient (Age > 2 1 years) Results The Bard Clamshell device was placed in a total of 132 patients. The only procedure related death occurred in the elderly patient previously mentioned. Among 120 of these patients, with selected lesions (Table 3) at the time of device implantation, 56.°£ were < 5 0 yrs of age, 28% age 50 to 70 yrs and 16% > age 70 yrs. The overall effective closure rate was 89%. Serious complications occurred in two patients, one related to the stroke previously mentioned and the other was due to tricuspid valve damage incurred during catheter removal of a device in a patient with a postmyocardial infarction VSD. Definite device arm fracture, noted at follow-up, occurred in 60% and complications definitely related to 'fracture occurred in only one patient. The latter consisted of thrombus formation on the left atrial portion of the device, noted echocardiographically and a recurrence of transient neurological changes: this device was surgically removed.

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23. Tynan M, Finley JP, Fontes V, Hess J, Kan J: Balloon angioplasty for the treatment of native coarctation: Results of valvuloplasty and angioplasty of congenital anomalies registry. Am J Cardio165:790-792, 1990 24. Kaine S, O'Brian-Smith E, MottAR, et ali Quantitative echocardiographic analysis of the aortic arch predict outcome of balloon angioplasty o[ native coarctation of the aorta. Circulation 94:1056:1062, 1996 25. Saul JP, Keane JF, Fellows KE, Lock JE: Balloon dilation angioplasty of postoperative aortic obstructions. Am J Cardio159:943-948, 1987 26. Morrow WR Vick GW, Nihill MR, et al: Balloon dilation of unoperated coarctation of the aorta: Short and intermediate-term results. J Am Coil Cardio! 11:133138, 1988 27. Fletcher SE, Nihill MR, Grifka RG 0'Laughlin MP, Muilins CE: Balloon angioplasty of native coarctation of the aorta: Mid term follow-up and prognostic factors. J Am Cell Cardio125(3)730-734, 1995 28. Mullins CE, O'Laughlin MP, Vick GW, et al: Implantation of balloon-expandable intravascular grafts by catheterization in pulmonary arteries and systemic veins. Circulation 77:(No 1)188-199, 1988 29. Benson LN Hamilton F, Dasmahapatra H, et ah Percutaneousimplantationof a balloon expandableendoprosthesisfor pulmonary artery stenosis:An experimental study. ,JAm Coil Cardio118:1303-1308,1991 30. O'Laughlin MP, Perry SB, Lock JE, Mullins CE: Use of endovascular stents ~ncongenital heart disease. Circulation 83:1923-1939, 1991 31. O'Laughli[q MP. Slack MC, Grifka RG, et al: Implantation and intermediate-term follow-up of stents in congenital heart disease. Circulation 88(2):605-6t4, 1993 32. Nakanishi T. Kondoh C, Nishikawa T, et al: Intravascular stents for management of pulmonary artery and right ventricular outflow obstruction. Heart & Vessels 9(1 ):40-48.1994 33. Hosking MC, Benson LN, Nakanishi -E Burrows PE: Use of endovascular stents in congenital heart disease. Circulation 83:1923-1939, 1991 34. Powell AJ, Lock JE, Keane JF, Perry SB: Prolongation of RV-PA conduit life span by percutaneous stent implantation: Intermediate-term results. CirculatiOn 92: 3282-3288, 1995 35. Morrow RW. Palmaz JC, Tio FO, et al: Re-expansion of balloon-expandablestents after growth. J Am Coil Cardio122:2007-2013, 1993 36. Grifka RG. Vick GW, O'Laughlin MP, et ah Balloon expandable intravascular stents: Aortic implantation and late further dilation in growing mmipigs. Am Heart J 126:(94):979-984, 1993 37. Ing F, Grifka RG, Nihill MR, Mullins CE: Redilation of intravascular stents in congenital heart defects. Circulation 88:(4):1-389. 1993 (pt 2) (abstr) 38. Morrow WR, smith VC Ehler W J, VanDellen AF, Mul]ins CE: Balloon angioplasty with stent implantation in experimental coarctation of the aorta. Circulation 89 (6):2677-2683, 1994 39. Redington AN, Hayes AM. Ho SY: Transcatheter stent placement to treat aortic coarctation in infancy. Br Heart J 69(1 ):80-82, 1993 40. Gianturco C, Anderson JH. Wallace S: Mechanical

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ence with 205 procedures of transcatheter closure of ductus arteriosus in 182 patientsl with special reference to residual shunts and 10ng-term follow-up. J Thorac Cardiovasc Surg 104:1721-1727, 1992 Lock JE, Cockerham JT Keane JF, et ah Transcatheter umbrella closure of congenital heart defects. Circulation 75:593-599, 1987 Lock JE, Block PC. McKay RG, et ah Transcatheter closure of ventricular septal defects. Circulation 78:361368 1988 Lock JE, Rome JJ, Davis R. et al: Transcatheter closure of atrial septal defects: Experimental studies. Circulation 79:1091-1099, 1989 Rome JJ, Keane JF, Perry SB et al: Double umbrella closure of atrial defects: Initial clinical applications. Circulation 82:751-758, 1990 Landzberg MJ, Bridges ND, Bittl JA: Transcatheter closure of atrial septal defects in adults platypneaorthodeoxia syndrome. J Am Coil Cardiol 19:289A, 1992 (abstr) Bridges ND, Lock JE, Castaneda AR: Modification of the Fontan operation of patients at increased risk. Circulation 82:751-758.1990 Bridges ND, Perry SB, Keane JF, et al: Preoperative transcatheter closure of congenital muscular ventricular septal defects. N Engl J Med 324:1312-1317, 1991 Bridges ND, Perry SB, Parness I, et al: Transcatheter closure of a large patent ductus arteriosus with the clamshell umbrella. J Am Coil Cardiol 18:1297-1302, 1991 Perry SB, vander Velde ME, Bridges ND, et al: Transcatheter closure of atrial anc~ventricular septal defects. Hertz 18:135-142, 1993 Rao PS, Sideris EB, Hausdorf G, et al: International experience with secundum atrial septal defect occlusion by the buttoned device. Am Heart J 128(5):10221035, 1994 Lloyd -I-R, Rao PS, Beekman RH, et ah Atrial septal defect occlusion with the buttoned device (a multiinstitutional U.S. trial). Am J Cardiol 73(4):286-291, 1994 Rao PS, Sideris EB, Haddad J, et al: Transcatheter occlusion of patent ductus arteriosus with adjustable buttoned device. Initial clinical experience. Circulation 88(3):1119-1126, 1993 Sideris EB, Leung M~ Yoon JH et al: Occlusion of large atrial septal defects with a centering buttoned device: Early clinical expenence. Am Heart J 131 (2): 356-359, 1996 Jenkins KJ. Newburger JW, Faherty C, et al: Midterm follow-up using the original Bard clamshell septal occiuder; complete experience at one center. Circulation 92(8):1-308 1995 (abstr)