- Email: [email protected]
Pulmonary Valve Replacement
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Pulmonary Valve Replacement: Indications and Options YOSHIO OOTAKI, MD, PHD; DEREK A. WILLIAMS, DO
S
urvival after surgical repair of congenital heart defects has continuously improved over the last several decades with advances in surgical techniques, cardiopulmonary bypass, and perioperative care. This has created the need to address the emerging long-term issues of older children and young adults with “repaired” congenital heart disease. Half of the patients who survive tetralogy of Fallot repair require pulmonary valve replacement (PVR) within 30 years. As a result, PVR or right ventricular outflow tract (RVOT) reconstruction is becoming the most frequent congenital heart surgical procedure performed on adolescents and young adults. More recently there is growing enthusiasm for percutaneously inserted bioprosthetic valves in the pulmonary position. In this chapter we will review the current indications and approach for PVR.
Indications PVR is required in various situations such as isolated pulmonary valvular disease or pulmonary insufficiency after repair of tetralogy of Fallot (Box 60.1). Current indications for PVR include symptomatic and asymptomatic patients with increased risk for right ventricular (RV) dilation, RV failure, exercise intolerance, arrhythmia, and sudden cardiac death (Box 60.2). Numerous studies have demonstrated the benefits of PVR, and guidelines for PVR in adults with CHD have been published by the American,1 Canadian,2 and European3 cardiac societies. These guidelines are clear in symptomatic patients with severe pulmonary regurgitation recommending PVR. However, they are less clear in asymptomatic patients with severe pulmonary regurgitation. PVR offers improvement in symptoms and RV function, but the sickest patients receive the least benefit and carry higher surgical risks. Given the limitations of echocardiography to accurately assess the RV, magnetic resonance imaging (MRI) has become the more preferable approach to assess pulmonary regurgitation fraction, RV volume, and RV ejection fraction. Several MRI studies have reported that RV volumes return to the normal range if the preoperative RV end-diastolic volume (RVEDV) index is less than 150 to 170 mL/m2 or the RV end-systolic volume is less than 80 to 90 mL/ m2.4-6 Additional findings such as an RV pressure more than twothirds systemic, a pulmonary-to-systemic flow ratio of more than 1.5 : 1, residual shunt, severe tricuspid regurgitation, an RVOT aneurysm, and reduced left ventricular function are also factors promoting a need for PVR. Maximal benefit from PVR seems to occur with earlier intervention before the RV suffers irreversible 720
change. Although aggressive application of PVR to younger children may result in a higher likelihood of reintervention within 10 years,7 waiting to perform PVR for preoperative RV end-systolic volume (RVESV) greater than 95 mL/m2 has an increased risk for suboptimal hemodynamic outcomes and adverse clinical events.5 Common candidates for PVR include patients with transannular patches for repair of tetralogy of Fallot, congenital pulmonary valve stenosis, repaired truncus arteriosus, and other anomalies requiring placement of an RV–pulmonary artery (PA) conduit. RV function is more successfully preserved in patients after repair of pulmonary stenosis compared with patients with pulmonary insufficiency following repair of tetralogy of Fallot.8 Patients with residual pulmonary insufficiency after congenital pulmonary stenosis repair had superior RV remodeling after PVR when compared with tetralogy of Fallot patients with residual pulmonary insufficiency after PVR.9 In patients requiring PVR, significant tricuspid regurgitation is more common in patients with pulmonary atresia and intact ventricular septum compared with patients with tetralogy of Fallot.10 Therefore complete knowledge of the original congenital heart defect is extremely important before PVR. In addition to the recommended indications for PVR, the optimal timing for PVR requires a thorough workup and discussion based on the individual patient. There is agreement that PVR is recommended in symptomatic patients with severe pulmonary insufficiency (particularly with RV dilation), heart failure, and new-onset arrhythmia. However, PVR is still controversial in asymptomatic patients. There is no randomized trial to prove PVR reduces long-term adverse clinical outcomes compared with medical treatment. Multicenter clinical registries will be necessary to assess long-term clinical benefit after PVR.
Pulmonary Valve Replacement Options (Box 60.3) Surgical PVR is becoming one of the most common operations in adult congenital heart disease. The mortality is reassuringly low, reported as 0.9% from the Society of Thoracic Surgeons Congenital Heart Surgery Database (STS CHSD) and 4.1% from the Adult Cardiac Surgery Database (STS ACSD).11 The risk of a major complication (temporary or permanent renal failure at discharge requiring dialysis, neurologic deficit persisting at discharge, atrioventricular block or arrhythmia requiring a permanent pacemaker, postoperative mechanical circulatory support, phrenic
CHAPTER 60 Pulmonary Valve Replacement: Indications and Options
• BOX 60.1 Primary Disease • • • •
Pulmonary valve stenosis Tetralogy of Fallot with or without pulmonary atresia Pulmonary atresia with intact ventricular septum Truncus arteriosus and other congenital heart defects repaired with an RV-PA conduit • Post Ross procedure PA, Pulmonary artery; RV, right ventricle.
• BOX 60.2 Indications for Pulmonary Valve
Replacement
Moderate or severe pulmonary regurgitation (regurgitation fraction ≥25%) I. Asymptomatic patient with two or more of the following criteria a. RV end-diastolic volume index >150 mL/m2 or z score >4. In patients whose body surface area falls outside published normal data: RV/LV end-diastolic volume ratio >2 b. RV end-systolic volume index >80 mL/m2 c. RV ejection fraction <47% d. LV ejection fraction <55% e. Large RVOT aneurysm f. QRS duration >140 ms g. Sustained tachyarrhythmia related to right heart volume load h. Other hemodynamically significant abnormalities: • RVOT obstruction with RV systolic pressure ≥2/3 systemic • Severe branch pulmonary artery stenosis (<30% flow to affected lung) not amenable to transcatheter therapy • ≥ Moderate tricuspid regurgitation • Left-to-right shunt from residual atrial or ventricular septal defects with pulmonary-to-systemic flow ratio ≥1.5 • Severe aortic regurgitation • Severe aortic dilation (diameter ≥5 cm) II. Symptomatic patients with one or more of the above criteria III. Special considerations a. In patients who underwent TOF repair at ≥3 years of age, PVR may be considered if fulfill ≥1 of the quantitative criteria in section I. b. In women with severe pulmonary regurgitation and RV dilation and/or dysfunction, PVR may be considered if fulfill ≥1 of the quantitative criteria in section I due to pregnancy-related complications. LV, Left ventricle; PVR, pulmonary valve replacement; RV, right ventricle; RVOT, right ventricular outflow tract; TOF, tetralogy of Fallot. From Geva T. Repaired tetralogy of Fallot: the roles of cardiovascular magnetic resonance in evaluating pathophysiology and for pulmonary valve replacement decision support. J Cardiovasc Magn Reson. 2011;13:9.
• BOX 60.3 Pulmonary Valve Replacement Options • • • • • •
Allograft Bioprosthetic stented valve Bioprosthetic stentless valve (Contegra, Freestyle) Mechanical valve ePTFE valve (monocusp, bicuspid, tricuspid) Transcatheter pulmonary valve (Melody, Sapien)
ePTFE, Expanded polytetrafluoroethylene.
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nerve injury, or any unplanned reintervention before discharge) is reported as 2.2% from the STS CHSD and 20.9% from STS ACSD. PVR carries higher morbidity and mortality in the adult population compared with the pediatric population, possibly secondary to a higher prevalence of other preoperative risk factors such as endocarditis. There is also an increasing volume of literature suggesting that the risk for PVR is significantly higher when performed by non–congenital heart surgeons and when patients are cared for in intensive care units that are not accustomed to caring for congenital heart patients.12,13 The difference between the mortality for PVR in the STS CHSD and the STS ACSD is likely not due to patient comorbidity alone.
Surgical Approach In the majority of PVR surgeries a repeat sternotomy is necessary. The risk of a reentry injury during repeat sternotomy is low (0.3% to 1.3%)14,15; however, major injury requires emergent cannulation to initiate cardiopulmonary bypass (CPB). There are clear risk factors that increase the risk of PVR in certain patients such as the existence of a transannular patch, a prior RV-PA conduit, or an enlarged and aneurysmal aorta; however, reentry injury is not associated with an increased risk of operative mortality in the current era. Typically CPB at normothermia or mild hypothermia is common for PVR. In the case of a residual atrial or ventricular level shunt, aortic cross-clamping with cardioplegic arrest of the heart is preferred over techniques such as “empty, beating” right heart surgery to reduce the risk of systemic air embolism. In general the favored recommendation is to avoid “empty, beating” heart surgery for congenital heart surgery due to the possibility of unrecognized residual shunts, and we recommend aortic cross-clamping and cardioplegic arrest unless the anatomy makes this more dangerous (e.g., a calcified, enlarged, or heavily scarred aorta). Ventricular fibrillation using an electric fibrillator is an alternative technique to avoid “empty, beating” heart surgery, which carries a risk for embolic brain injury in some patients. The pulmonary annulus is visualized through a longitudinal incision to the RVOT. An appropriate-size valve or valved conduit can be chosen, and the selected valve can be placed using a wide variety of surgical techniques. Allograft. Allografts (Fig. 60.1A) have been widely used for more than 50 years. Early outcomes with allografts have been excellent, especially in neonates and infants; however, valve deterioration over time has been an issue, especially in smaller allografts.16 Decellularized pulmonary homografts have better early to midterm results when compared with conventional homografts or to bovine jugular vein (BJV) conduits.17 Freedom from conduit dysfunction was significantly better at 10 years in decellularized pulmonary homografts (83%) compared with conventional pulmonary homografts (58%).18 However, long-term outcomes beyond 10 years have been discouraging, especially in small children. In some countries such as Japan, allografts are not widely available. Bioprosthetic Stented Valve. The durability of bioprosthetic stented valves (see Fig. 60.1B) in the aortic position over time have greatly improved. When a stented, bioprosthetic valve is used, a patch pulmonary arterioplasty to augment the size of the RVOT can be used to allow placement of an adequate-size prosthesis (Fig. 60.2). Comparison of results with the use of stented bioprosthetic valves in the pulmonary position demonstrate that the durability in the pulmonary position in young patients is suboptimal, mainly
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A
B
C
D
E
F
• Figure 60.1
Various types of commercially available valves that can be inserted into the pulmonary position. (A) Cadaver allograft pulmonary valve. (B) Stented bioprosthetic valve (bovine and porcine). (C) Contegra (bovine jugular vein) bioprosthesis. (D) Medtronic stentless porcine root. (E) Mechanical (St. Jude). (F) Melody stented bioprosthesis (transcatheter insertion).
due to dystrophic calcification and relative stenosis of the valve opening with changes in body size via somatic growth over time. Kwak and associates19 reported that patients more than 20 years of age showed no valvular dysfunction during nearly 14 years of follow-up. However, patients less than 20 years of age showed a 98.5% freedom from valvular dysfunction at 5 years, but this decreased to 68.2% at 10 years, and only 24.7% at 14 years, thus indicating significantly worse outcomes compared with patients more than 20 years of age. Lee and associates compared the performance of three types of bioprostheses (stented porcine, stented bovine pericardial, and stentless porcine valves). They reported freedom from repeat PVR at 10 years at 84.6% for stented bovine pericardial valves, 48.5% for stented porcine valves, and 31.2% for stentless porcine valves.20 Buchholz and associates could not identify any differences between the durability of stented biologic valves with bovine pericardial or porcine leaflets. However, considering that the pressure gradient across the valve increased sooner in the pericardial group, these results suggest that bovine valves might be preferred over porcine valves.21 Chen and associates22 reported that freedom from reintervention was similar for the porcine and bovine pericardial valves and the reintervention-free survival rate at 5 and 10 years was 94% and 36%, respectively. Of note, these studies were not randomized trials comparing one valve over others. A prospective randomized trial would be necessary to investigate the best stented pulmonary valve to be used in the pediatric population. However, the available data have led most practitioners to choose stented bovine pericardial valves as the current stented bioprosthesis of choice and in fact to use these preferentially over stentless porcine bioprostheses as well. Bioprosthetic Stentless Valve. The BJV (Contegra, Medtronic Inc., Minneapolis, MN) was introduced into clinical practice as an alternative to the use of homografts in 199923 (see Fig. 60.1C).
The recognized advantages of the BJV include (1) the structural continuity between the wall of the jugular vein of the conduit and valve leaflets, which provides optimal hemodynamics because of the ideal effective orifice area; (2) the unlimited availability in sizes from 12 to 22 mm in diameter, representing a good alternative to the homograft shortage, particularly for the smaller sizes; and (3) the availability of a long inflow and outflow length, which obviates the need for either proximal or distal augmentation, thus facilitating conduit tailoring and positioning, helping to avoid potential distortion and sternal compression. BJVs are associated with a significantly greater risk of late endocarditis. The reintervention-free survival rate is concerning and has been reported at 5, 10, and 15 years as 73%, 45%, and 26%, respectively.24 BJVs might have advantages for small children (less than 2 years of age) because of availability in small sizes and the expected need for replacement making long-term durability less of a factor.7 The Medtronic Freestyle valve is a stentless bioprosthesis derived from the porcine aortic root (see Fig. 60.1D) and decellularized using glutaraldehyde and then treated with alpha-amino oleic acid to minimize xenograft calcification. Potential advantages of the Freestyle valve include the availability of a range of larger sizes (19 to 29 mm) and the flexible nature of the bioprosthesis, allowing for easy implantation in curved RVOTs. The reintervention-free survival rate was reported as 85% at 5 years and 71% at 10 years.25 Long-term durability is an issue, though it performs equally well compared with the homograft. Mechanical Valve. The vast majority of patients, especially children who require PVR, obtain a tissue valve because of the relatively good durability and the lack of a need for anticoagulation. Although the thromboembolic risk after PVR with mechanical valves is presumed to be high, recent studies suggest promising midterm results.26 Freedom from PVR reoperation after 5 and 10
CHAPTER 60 Pulmonary Valve Replacement: Indications and Options
A
B
D
C • Figure 60.2
Technique for placement of stented bioprosthetic valve in the right ventricular outflow tract (RVOT). (A) A longitudinal incision is made in the RVOT extending out to the pulmonary bifurcation. (B) After sizing for the appropriate valve, it is retained on its “handle,” and a continuous suture line is placed along the posterior portion of the RVOT and the top part of the valve sewing ring. Notice that the valve is oriented “backward,” but when the sutures are tightened, the valve will “flip” into its desired orientation. (C) The valve is seated into position, and the posterior suture line is continued to the edge of the incision in the RVOT. (D) A prosthetic patch is then used as a “roof” over the valve and RVOT incision. This allows placement of a large valve into the RVOT. Notice that the anterior portion of the valve sewing ring is secured to the outflow patch.
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years was reported as 96% and 89%, respectively. Performance of mechanical prostheses (Fig. 60.1E) in the pulmonary position may improve when valvular thrombosis is prevented by prudent patient selection, avoiding mechanical valves in patients at increased risk of valvular thrombosis, and by strict compliance to anticoagulation therapy. An important disadvantage of the mechanical valve in the pulmonary position is its interference with permitting catheter intervention to the distal pulmonary arteries—the mechanical disks and architecture of the valve impose a formidable impediment to floating catheters into the distal pulmonary arteries. The mechanical valve in the pulmonary position, although not a commonly preferred option, can be a reasonable choice for complex patients who may be receiving one final procedure aimed at providing a durable PVR, who have normal distal pulmonary arteries, and for whom long-term anticoagulation is acceptable. Expanded Polytetrafluoroethylene Valve. Expanded polytetrafluoroethylene (ePTFE) has been reported for PVR. Monocusp valves were reported in 2002,27 and bicuspid valves have been created in situ and more recently in conduits.28,29 Tricuspid valves have been created primarily in Japan, where allografts have not been widely available.30 The follow-up now exceeds 10 years, and freedom from reoperation has been 100% at 5 years and 95.4% at 10 years. Ootaki and associates31 described a simplified technique to create a tricuspid ePTFE valved conduit, which consists of commercially available ePTFE graft and 0.1-mm thick ePTFE membrane (WL Gore & Associates, Flagstaff, AZ) (Fig. 60.3), and have shown similar, excellent results with freedom from valve replacement at 100% at 4 years. The trileaflet ePTFE valve is shorter than the bicuspid valve (because valve height is related to leaflet length, trileaflet valves have shorter leaflets and thus a shorter valve height, resulting in shorter conduit length). The
Bicuspid
• Figure 60.3
Tricuspid
A bicuspid and tricuspid polytetrafluoroethylene valve. The potential advantages of the tricuspid valve versus the bicuspid valve are discussed in the text.
trileaflet valve potentially has superior hemodynamics to a bileaflet valve, although this has not yet been demonstrated in human recipients. Homografts or BJVs, even available for small children who require RVOT replacement, have potential problems with durability as described earlier. When they are used in small sizes (for smaller patients), conduit replacement is an expected eventuality. However, compared with homografts and BJV options, ePTFE valved conduits have a more optimistic outlook. Yamashita and associates32 reported that freedom from conduit replacement and reintervention at 5 years was 90.1% and 77.2%, respectively, after implantation of an ePTFE valved conduit less than or equal to 16 mm in diameter.
Transcatheter Pulmonary Valve Replacement Transcatheter PVR was first reported in humans in 2000.33 Since then transcatheter PVR has emerged as a variable alternative to surgical PVR in patients with RVOT dysfunction. The Medtronic Melody transcatheter pulmonary valve (TPV) (Medtronic, Minneapolis, MN) is composed of a BJV valve sutured within a platinum iridium stent (see Fig. 60.1F). The multicenter US trial was completed in 2009 and showed favorable results.34,35 Although there was an issue of stent fracture, altering the implant approach with bare metal prestenting of the preexisting conduit reduced this risk significantly.36 The Food and Drug Administration (FDA) approved its full commercial issue in 2015. The Melody TPV is marketed for failing conduits 16 mm or larger at the time of surgical placement. The valve comes in two sizes (16 mm and 18 mm) with the 16-mm valve achieving a maximal diameter of 20 mm and the 18-mm valve achieving a maximal diameter of 22 mm. Cheatham and associates37 reported successful maximal dilation of the 18-mm valve up to 24 mm with only mild residual regurgitation. The Edwards Sapien system is widely used in the aortic position, and it was first reported in the pulmonary position in 2006.38 The Edwards Sapien XT valve is a bovine pericardial tissue valve mounted within a cobalt chromium stent and comes in diameters of 20, 23, 26, and 29 mm. The Sapien XT valve received FDA approval for implantation in the pulmonary position in 2016. The Sapien 3 is the newest generation and awaits FDA approval for the pulmonary position. Presently the primary usage of the transcatheter approach is for patients with a failing RVOT conduit and an RVOT diameter (or previous conduit size) of less than 28 mm. With the availability of the Sapien valve, which can reach 30 mm in diameter, case reports are emerging showing successful implantation in the native RVOT primary in patients with a transannular patch repair for tetralogy of Fallot. Additionally, a trial in under way studying new valve designs for the native RVOT. Coronary artery compression is one of the main concerns at the time of transcatheter PVR. The incidence of coronary artery compression has been found to be 5% during test balloon inflation39 and should be checked for before finalizing inflation of a stented valved conduit in the RVOT. Conduit tear has been another concern during implant. A retrospective review of the multicenter US trial revealed a rate of 6%. The commercially available NuMED Covered CheathamPlatinum Stent was 98% effective in preventing or repairing these tears.40 Endocarditis is one of the main concerns after transcatheter PVR. Freedom from endocarditis at 5 years was 89%36 and has been reported as a frequent midterm outcome in numerous series.
CHAPTER 60 Pulmonary Valve Replacement: Indications and Options
Outcomes after transcatheter PVR are comparable with the surgical approach in the short-term and midterm follow-up. Long-term data are needed to make a final judgment on the most appropriate patient selection for transcatheter PVR.
Hybrid Approach Several hybrid approaches have been reported using the RV approach for smaller-size patients41 or performing main PA plication.42 These approaches can prevent the exposure to CPB and reduce transfusions, which have resulted in reducing surgical morbidity and mortality. However, there are no long-term data to support any benefits to this approach. Surgical mortality and morbidity after surgical PVR have been minimal in the current era. Presently the hybrid PVR approach is best suited for patients with higher risks for surgery employing CPB and should be based on the individual factors involved. This is a team dynamic between the surgeon and the interventionist that allows for creative approaches to complex patients.
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Summary Currently there are multiple options for PVR, and the future will undoubtedly provide more. Longevity of the various valves is dependent upon the type of conduit and age/size of the patient at implantation. The ePTFE valved conduit shows particular promise as a preeminent valve in children and adolescents. For adolescents and young adults there exist several options with proven durability of each valve. To date there is no “perfect” valve for providing a permanent solution in pulmonary position, though presently surgical PVR followed by transcatheter PVR is the preferred option to limit future surgical intervention.
References A complete list of references is available at ExpertConsult.com
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CHAPTER 60 Pulmonary Valve Replacement: Indications and Options
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to 7 years after transcatheter pulmonary valve replacement in the US Melody Valve Investigational Device Exemption Trial. Circulation. 2015;131:1960–1970. 37. Cheatham SL, Holzer RJ, Chisolm JL, Cheatham JP. The Medtronic Melody® transcatheter pulmonary valve implanted at 24-mm diameter—it works. Catheter Cardiovasc Interv. 2013;82:816– 823. 38. Garay F, Webb J, Hijazi ZM. Percutaneous replacement of pulmonary valve using the Edwards-Cribier percutaneous heart valve: first report in a human patient. Catheter Cardiovasc Interv. 2006;67:659–662. 39. Morray BH, McElhinney DB, Cheatham JP, Zahn EM, Berman DP, Sullivan PM, et al. Risk of coronary artery compression among patients referred for transcatheter pulmonary
valve implantation: a multicenter experience. Circ Cardiovasc Interv. 2013;6:535–542. 40. Bishnoi RN, Jones TK, Kreutzer J, Ringel RE. NuMED Covered Cheatham-Platinum Stent for treatment or prevention of right ventricular outflow tract conduit disruption during transcatheter pulmonary valve replacement. Catheter Cardiovasc Interv. 2015;88:421–427. 41. Holoshitz N, Ilbawi MN, Amin Z. Periventricular Melody valve implantation in a 12 kg child. Catheter Cardiovasc Interv. 2013;82:824–827. 42. Sosnowski C, Matella T, Fogg L, Ilbawi M, Nagaraj H, Kavinsky C, et al. Hybrid pulmonary artery plication followed by transcatheter pulmonary valve replacement: comparison with surgical PVR. Catheter Cardiovasc Interv. 2016;88:804–810.
Pulmonary Valve Replacement: Indications and Options YOSHIO OOTAKI, MD, PHD; DEREK A. WILLIAMS, DO
S
urvival after surgical repair of congenital heart defects has continuously improved over the last several decades with advances in surgical techniques, cardiopulmonary bypass, and perioperative care. This has created the need to address the emerging long-term issues of older children and young adults with “repaired” congenital heart disease. Half of the patients who survive tetralogy of Fallot repair require pulmonary valve replacement (PVR) within 30 years. As a result, PVR or right ventricular outflow tract (RVOT) reconstruction is becoming the most frequent congenital heart surgical procedure performed on adolescents and young adults. More recently there is growing enthusiasm for percutaneously inserted bioprosthetic valves in the pulmonary position. In this chapter we will review the current indications and approach for PVR.
Indications PVR is required in various situations such as isolated pulmonary valvular disease or pulmonary insufficiency after repair of tetralogy of Fallot (Box 60.1). Current indications for PVR include symptomatic and asymptomatic patients with increased risk for right ventricular (RV) dilation, RV failure, exercise intolerance, arrhythmia, and sudden cardiac death (Box 60.2). Numerous studies have demonstrated the benefits of PVR, and guidelines for PVR in adults with CHD have been published by the American,1 Canadian,2 and European3 cardiac societies. These guidelines are clear in symptomatic patients with severe pulmonary regurgitation recommending PVR. However, they are less clear in asymptomatic patients with severe pulmonary regurgitation. PVR offers improvement in symptoms and RV function, but the sickest patients receive the least benefit and carry higher surgical risks. Given the limitations of echocardiography to accurately assess the RV, magnetic resonance imaging (MRI) has become the more preferable approach to assess pulmonary regurgitation fraction, RV volume, and RV ejection fraction. Several MRI studies have reported that RV volumes return to the normal range if the preoperative RV end-diastolic volume (RVEDV) index is less than 150 to 170 mL/m2 or the RV end-systolic volume is less than 80 to 90 mL/ m2.4-6 Additional findings such as an RV pressure more than twothirds systemic, a pulmonary-to-systemic flow ratio of more than 1.5 : 1, residual shunt, severe tricuspid regurgitation, an RVOT aneurysm, and reduced left ventricular function are also factors promoting a need for PVR. Maximal benefit from PVR seems to occur with earlier intervention before the RV suffers irreversible 720
change. Although aggressive application of PVR to younger children may result in a higher likelihood of reintervention within 10 years,7 waiting to perform PVR for preoperative RV end-systolic volume (RVESV) greater than 95 mL/m2 has an increased risk for suboptimal hemodynamic outcomes and adverse clinical events.5 Common candidates for PVR include patients with transannular patches for repair of tetralogy of Fallot, congenital pulmonary valve stenosis, repaired truncus arteriosus, and other anomalies requiring placement of an RV–pulmonary artery (PA) conduit. RV function is more successfully preserved in patients after repair of pulmonary stenosis compared with patients with pulmonary insufficiency following repair of tetralogy of Fallot.8 Patients with residual pulmonary insufficiency after congenital pulmonary stenosis repair had superior RV remodeling after PVR when compared with tetralogy of Fallot patients with residual pulmonary insufficiency after PVR.9 In patients requiring PVR, significant tricuspid regurgitation is more common in patients with pulmonary atresia and intact ventricular septum compared with patients with tetralogy of Fallot.10 Therefore complete knowledge of the original congenital heart defect is extremely important before PVR. In addition to the recommended indications for PVR, the optimal timing for PVR requires a thorough workup and discussion based on the individual patient. There is agreement that PVR is recommended in symptomatic patients with severe pulmonary insufficiency (particularly with RV dilation), heart failure, and new-onset arrhythmia. However, PVR is still controversial in asymptomatic patients. There is no randomized trial to prove PVR reduces long-term adverse clinical outcomes compared with medical treatment. Multicenter clinical registries will be necessary to assess long-term clinical benefit after PVR.
Pulmonary Valve Replacement Options (Box 60.3) Surgical PVR is becoming one of the most common operations in adult congenital heart disease. The mortality is reassuringly low, reported as 0.9% from the Society of Thoracic Surgeons Congenital Heart Surgery Database (STS CHSD) and 4.1% from the Adult Cardiac Surgery Database (STS ACSD).11 The risk of a major complication (temporary or permanent renal failure at discharge requiring dialysis, neurologic deficit persisting at discharge, atrioventricular block or arrhythmia requiring a permanent pacemaker, postoperative mechanical circulatory support, phrenic
CHAPTER 60 Pulmonary Valve Replacement: Indications and Options
• BOX 60.1 Primary Disease • • • •
Pulmonary valve stenosis Tetralogy of Fallot with or without pulmonary atresia Pulmonary atresia with intact ventricular septum Truncus arteriosus and other congenital heart defects repaired with an RV-PA conduit • Post Ross procedure PA, Pulmonary artery; RV, right ventricle.
• BOX 60.2 Indications for Pulmonary Valve
Replacement
Moderate or severe pulmonary regurgitation (regurgitation fraction ≥25%) I. Asymptomatic patient with two or more of the following criteria a. RV end-diastolic volume index >150 mL/m2 or z score >4. In patients whose body surface area falls outside published normal data: RV/LV end-diastolic volume ratio >2 b. RV end-systolic volume index >80 mL/m2 c. RV ejection fraction <47% d. LV ejection fraction <55% e. Large RVOT aneurysm f. QRS duration >140 ms g. Sustained tachyarrhythmia related to right heart volume load h. Other hemodynamically significant abnormalities: • RVOT obstruction with RV systolic pressure ≥2/3 systemic • Severe branch pulmonary artery stenosis (<30% flow to affected lung) not amenable to transcatheter therapy • ≥ Moderate tricuspid regurgitation • Left-to-right shunt from residual atrial or ventricular septal defects with pulmonary-to-systemic flow ratio ≥1.5 • Severe aortic regurgitation • Severe aortic dilation (diameter ≥5 cm) II. Symptomatic patients with one or more of the above criteria III. Special considerations a. In patients who underwent TOF repair at ≥3 years of age, PVR may be considered if fulfill ≥1 of the quantitative criteria in section I. b. In women with severe pulmonary regurgitation and RV dilation and/or dysfunction, PVR may be considered if fulfill ≥1 of the quantitative criteria in section I due to pregnancy-related complications. LV, Left ventricle; PVR, pulmonary valve replacement; RV, right ventricle; RVOT, right ventricular outflow tract; TOF, tetralogy of Fallot. From Geva T. Repaired tetralogy of Fallot: the roles of cardiovascular magnetic resonance in evaluating pathophysiology and for pulmonary valve replacement decision support. J Cardiovasc Magn Reson. 2011;13:9.
• BOX 60.3 Pulmonary Valve Replacement Options • • • • • •
Allograft Bioprosthetic stented valve Bioprosthetic stentless valve (Contegra, Freestyle) Mechanical valve ePTFE valve (monocusp, bicuspid, tricuspid) Transcatheter pulmonary valve (Melody, Sapien)
ePTFE, Expanded polytetrafluoroethylene.
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nerve injury, or any unplanned reintervention before discharge) is reported as 2.2% from the STS CHSD and 20.9% from STS ACSD. PVR carries higher morbidity and mortality in the adult population compared with the pediatric population, possibly secondary to a higher prevalence of other preoperative risk factors such as endocarditis. There is also an increasing volume of literature suggesting that the risk for PVR is significantly higher when performed by non–congenital heart surgeons and when patients are cared for in intensive care units that are not accustomed to caring for congenital heart patients.12,13 The difference between the mortality for PVR in the STS CHSD and the STS ACSD is likely not due to patient comorbidity alone.
Surgical Approach In the majority of PVR surgeries a repeat sternotomy is necessary. The risk of a reentry injury during repeat sternotomy is low (0.3% to 1.3%)14,15; however, major injury requires emergent cannulation to initiate cardiopulmonary bypass (CPB). There are clear risk factors that increase the risk of PVR in certain patients such as the existence of a transannular patch, a prior RV-PA conduit, or an enlarged and aneurysmal aorta; however, reentry injury is not associated with an increased risk of operative mortality in the current era. Typically CPB at normothermia or mild hypothermia is common for PVR. In the case of a residual atrial or ventricular level shunt, aortic cross-clamping with cardioplegic arrest of the heart is preferred over techniques such as “empty, beating” right heart surgery to reduce the risk of systemic air embolism. In general the favored recommendation is to avoid “empty, beating” heart surgery for congenital heart surgery due to the possibility of unrecognized residual shunts, and we recommend aortic cross-clamping and cardioplegic arrest unless the anatomy makes this more dangerous (e.g., a calcified, enlarged, or heavily scarred aorta). Ventricular fibrillation using an electric fibrillator is an alternative technique to avoid “empty, beating” heart surgery, which carries a risk for embolic brain injury in some patients. The pulmonary annulus is visualized through a longitudinal incision to the RVOT. An appropriate-size valve or valved conduit can be chosen, and the selected valve can be placed using a wide variety of surgical techniques. Allograft. Allografts (Fig. 60.1A) have been widely used for more than 50 years. Early outcomes with allografts have been excellent, especially in neonates and infants; however, valve deterioration over time has been an issue, especially in smaller allografts.16 Decellularized pulmonary homografts have better early to midterm results when compared with conventional homografts or to bovine jugular vein (BJV) conduits.17 Freedom from conduit dysfunction was significantly better at 10 years in decellularized pulmonary homografts (83%) compared with conventional pulmonary homografts (58%).18 However, long-term outcomes beyond 10 years have been discouraging, especially in small children. In some countries such as Japan, allografts are not widely available. Bioprosthetic Stented Valve. The durability of bioprosthetic stented valves (see Fig. 60.1B) in the aortic position over time have greatly improved. When a stented, bioprosthetic valve is used, a patch pulmonary arterioplasty to augment the size of the RVOT can be used to allow placement of an adequate-size prosthesis (Fig. 60.2). Comparison of results with the use of stented bioprosthetic valves in the pulmonary position demonstrate that the durability in the pulmonary position in young patients is suboptimal, mainly
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A
B
C
D
E
F
• Figure 60.1
Various types of commercially available valves that can be inserted into the pulmonary position. (A) Cadaver allograft pulmonary valve. (B) Stented bioprosthetic valve (bovine and porcine). (C) Contegra (bovine jugular vein) bioprosthesis. (D) Medtronic stentless porcine root. (E) Mechanical (St. Jude). (F) Melody stented bioprosthesis (transcatheter insertion).
due to dystrophic calcification and relative stenosis of the valve opening with changes in body size via somatic growth over time. Kwak and associates19 reported that patients more than 20 years of age showed no valvular dysfunction during nearly 14 years of follow-up. However, patients less than 20 years of age showed a 98.5% freedom from valvular dysfunction at 5 years, but this decreased to 68.2% at 10 years, and only 24.7% at 14 years, thus indicating significantly worse outcomes compared with patients more than 20 years of age. Lee and associates compared the performance of three types of bioprostheses (stented porcine, stented bovine pericardial, and stentless porcine valves). They reported freedom from repeat PVR at 10 years at 84.6% for stented bovine pericardial valves, 48.5% for stented porcine valves, and 31.2% for stentless porcine valves.20 Buchholz and associates could not identify any differences between the durability of stented biologic valves with bovine pericardial or porcine leaflets. However, considering that the pressure gradient across the valve increased sooner in the pericardial group, these results suggest that bovine valves might be preferred over porcine valves.21 Chen and associates22 reported that freedom from reintervention was similar for the porcine and bovine pericardial valves and the reintervention-free survival rate at 5 and 10 years was 94% and 36%, respectively. Of note, these studies were not randomized trials comparing one valve over others. A prospective randomized trial would be necessary to investigate the best stented pulmonary valve to be used in the pediatric population. However, the available data have led most practitioners to choose stented bovine pericardial valves as the current stented bioprosthesis of choice and in fact to use these preferentially over stentless porcine bioprostheses as well. Bioprosthetic Stentless Valve. The BJV (Contegra, Medtronic Inc., Minneapolis, MN) was introduced into clinical practice as an alternative to the use of homografts in 199923 (see Fig. 60.1C).
The recognized advantages of the BJV include (1) the structural continuity between the wall of the jugular vein of the conduit and valve leaflets, which provides optimal hemodynamics because of the ideal effective orifice area; (2) the unlimited availability in sizes from 12 to 22 mm in diameter, representing a good alternative to the homograft shortage, particularly for the smaller sizes; and (3) the availability of a long inflow and outflow length, which obviates the need for either proximal or distal augmentation, thus facilitating conduit tailoring and positioning, helping to avoid potential distortion and sternal compression. BJVs are associated with a significantly greater risk of late endocarditis. The reintervention-free survival rate is concerning and has been reported at 5, 10, and 15 years as 73%, 45%, and 26%, respectively.24 BJVs might have advantages for small children (less than 2 years of age) because of availability in small sizes and the expected need for replacement making long-term durability less of a factor.7 The Medtronic Freestyle valve is a stentless bioprosthesis derived from the porcine aortic root (see Fig. 60.1D) and decellularized using glutaraldehyde and then treated with alpha-amino oleic acid to minimize xenograft calcification. Potential advantages of the Freestyle valve include the availability of a range of larger sizes (19 to 29 mm) and the flexible nature of the bioprosthesis, allowing for easy implantation in curved RVOTs. The reintervention-free survival rate was reported as 85% at 5 years and 71% at 10 years.25 Long-term durability is an issue, though it performs equally well compared with the homograft. Mechanical Valve. The vast majority of patients, especially children who require PVR, obtain a tissue valve because of the relatively good durability and the lack of a need for anticoagulation. Although the thromboembolic risk after PVR with mechanical valves is presumed to be high, recent studies suggest promising midterm results.26 Freedom from PVR reoperation after 5 and 10
CHAPTER 60 Pulmonary Valve Replacement: Indications and Options
A
B
D
C • Figure 60.2
Technique for placement of stented bioprosthetic valve in the right ventricular outflow tract (RVOT). (A) A longitudinal incision is made in the RVOT extending out to the pulmonary bifurcation. (B) After sizing for the appropriate valve, it is retained on its “handle,” and a continuous suture line is placed along the posterior portion of the RVOT and the top part of the valve sewing ring. Notice that the valve is oriented “backward,” but when the sutures are tightened, the valve will “flip” into its desired orientation. (C) The valve is seated into position, and the posterior suture line is continued to the edge of the incision in the RVOT. (D) A prosthetic patch is then used as a “roof” over the valve and RVOT incision. This allows placement of a large valve into the RVOT. Notice that the anterior portion of the valve sewing ring is secured to the outflow patch.
723
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years was reported as 96% and 89%, respectively. Performance of mechanical prostheses (Fig. 60.1E) in the pulmonary position may improve when valvular thrombosis is prevented by prudent patient selection, avoiding mechanical valves in patients at increased risk of valvular thrombosis, and by strict compliance to anticoagulation therapy. An important disadvantage of the mechanical valve in the pulmonary position is its interference with permitting catheter intervention to the distal pulmonary arteries—the mechanical disks and architecture of the valve impose a formidable impediment to floating catheters into the distal pulmonary arteries. The mechanical valve in the pulmonary position, although not a commonly preferred option, can be a reasonable choice for complex patients who may be receiving one final procedure aimed at providing a durable PVR, who have normal distal pulmonary arteries, and for whom long-term anticoagulation is acceptable. Expanded Polytetrafluoroethylene Valve. Expanded polytetrafluoroethylene (ePTFE) has been reported for PVR. Monocusp valves were reported in 2002,27 and bicuspid valves have been created in situ and more recently in conduits.28,29 Tricuspid valves have been created primarily in Japan, where allografts have not been widely available.30 The follow-up now exceeds 10 years, and freedom from reoperation has been 100% at 5 years and 95.4% at 10 years. Ootaki and associates31 described a simplified technique to create a tricuspid ePTFE valved conduit, which consists of commercially available ePTFE graft and 0.1-mm thick ePTFE membrane (WL Gore & Associates, Flagstaff, AZ) (Fig. 60.3), and have shown similar, excellent results with freedom from valve replacement at 100% at 4 years. The trileaflet ePTFE valve is shorter than the bicuspid valve (because valve height is related to leaflet length, trileaflet valves have shorter leaflets and thus a shorter valve height, resulting in shorter conduit length). The
Bicuspid
• Figure 60.3
Tricuspid
A bicuspid and tricuspid polytetrafluoroethylene valve. The potential advantages of the tricuspid valve versus the bicuspid valve are discussed in the text.
trileaflet valve potentially has superior hemodynamics to a bileaflet valve, although this has not yet been demonstrated in human recipients. Homografts or BJVs, even available for small children who require RVOT replacement, have potential problems with durability as described earlier. When they are used in small sizes (for smaller patients), conduit replacement is an expected eventuality. However, compared with homografts and BJV options, ePTFE valved conduits have a more optimistic outlook. Yamashita and associates32 reported that freedom from conduit replacement and reintervention at 5 years was 90.1% and 77.2%, respectively, after implantation of an ePTFE valved conduit less than or equal to 16 mm in diameter.
Transcatheter Pulmonary Valve Replacement Transcatheter PVR was first reported in humans in 2000.33 Since then transcatheter PVR has emerged as a variable alternative to surgical PVR in patients with RVOT dysfunction. The Medtronic Melody transcatheter pulmonary valve (TPV) (Medtronic, Minneapolis, MN) is composed of a BJV valve sutured within a platinum iridium stent (see Fig. 60.1F). The multicenter US trial was completed in 2009 and showed favorable results.34,35 Although there was an issue of stent fracture, altering the implant approach with bare metal prestenting of the preexisting conduit reduced this risk significantly.36 The Food and Drug Administration (FDA) approved its full commercial issue in 2015. The Melody TPV is marketed for failing conduits 16 mm or larger at the time of surgical placement. The valve comes in two sizes (16 mm and 18 mm) with the 16-mm valve achieving a maximal diameter of 20 mm and the 18-mm valve achieving a maximal diameter of 22 mm. Cheatham and associates37 reported successful maximal dilation of the 18-mm valve up to 24 mm with only mild residual regurgitation. The Edwards Sapien system is widely used in the aortic position, and it was first reported in the pulmonary position in 2006.38 The Edwards Sapien XT valve is a bovine pericardial tissue valve mounted within a cobalt chromium stent and comes in diameters of 20, 23, 26, and 29 mm. The Sapien XT valve received FDA approval for implantation in the pulmonary position in 2016. The Sapien 3 is the newest generation and awaits FDA approval for the pulmonary position. Presently the primary usage of the transcatheter approach is for patients with a failing RVOT conduit and an RVOT diameter (or previous conduit size) of less than 28 mm. With the availability of the Sapien valve, which can reach 30 mm in diameter, case reports are emerging showing successful implantation in the native RVOT primary in patients with a transannular patch repair for tetralogy of Fallot. Additionally, a trial in under way studying new valve designs for the native RVOT. Coronary artery compression is one of the main concerns at the time of transcatheter PVR. The incidence of coronary artery compression has been found to be 5% during test balloon inflation39 and should be checked for before finalizing inflation of a stented valved conduit in the RVOT. Conduit tear has been another concern during implant. A retrospective review of the multicenter US trial revealed a rate of 6%. The commercially available NuMED Covered CheathamPlatinum Stent was 98% effective in preventing or repairing these tears.40 Endocarditis is one of the main concerns after transcatheter PVR. Freedom from endocarditis at 5 years was 89%36 and has been reported as a frequent midterm outcome in numerous series.
CHAPTER 60 Pulmonary Valve Replacement: Indications and Options
Outcomes after transcatheter PVR are comparable with the surgical approach in the short-term and midterm follow-up. Long-term data are needed to make a final judgment on the most appropriate patient selection for transcatheter PVR.
Hybrid Approach Several hybrid approaches have been reported using the RV approach for smaller-size patients41 or performing main PA plication.42 These approaches can prevent the exposure to CPB and reduce transfusions, which have resulted in reducing surgical morbidity and mortality. However, there are no long-term data to support any benefits to this approach. Surgical mortality and morbidity after surgical PVR have been minimal in the current era. Presently the hybrid PVR approach is best suited for patients with higher risks for surgery employing CPB and should be based on the individual factors involved. This is a team dynamic between the surgeon and the interventionist that allows for creative approaches to complex patients.
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Summary Currently there are multiple options for PVR, and the future will undoubtedly provide more. Longevity of the various valves is dependent upon the type of conduit and age/size of the patient at implantation. The ePTFE valved conduit shows particular promise as a preeminent valve in children and adolescents. For adolescents and young adults there exist several options with proven durability of each valve. To date there is no “perfect” valve for providing a permanent solution in pulmonary position, though presently surgical PVR followed by transcatheter PVR is the preferred option to limit future surgical intervention.
References A complete list of references is available at ExpertConsult.com
References 1. Warnes CA, Williams RG, Bashore TM, Child JS, Connolly HM, Dearani JA, et al. ACC/AHA 2008 Guidelines for the Management of Adults with Congenital Heart Disease: Executive Summary: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (writing committee to develop guidelines for the management of adults with congenital heart disease). Circulation. 2008;118:2395–2451. 2. Silversides CK, Kiess M, Beauchesne L, Bradley T, Connelly M, Niwa K, et al. Canadian Cardiovascular Society 2009 Consensus Conference on the management of adults with congenital heart disease: outflow tract obstruction, coarctation of the aorta, tetralogy of Fallot, Ebstein anomaly and Marfan’s syndrome. Can J Cardiol. 2010;26:e80–e97. 3. Baumgartner H, Bonhoeffer P, De Groot NM, de Haan F, Deanfield JE, Galie N, et al. ESC Guidelines for the management of grown-up congenital heart disease (new version 2010). Eur Heart J. 2010;31:2915–2957. 4. Alvarez-Fuente M, Garrido-Lestache E, Fernandez-Pineda L, Romera B, Sánchez I, Centella T, et al. Timing of pulmonary valve replacement: how much can the right ventricle dilate before it loses its remodeling potential? Pediatr Cardiol. 2016;37:601–605. 5. Bokma JP, Winter MM, Oosterhof T, Vliegen HW, van Dijk AP, Hazekamp MG, et al. Preoperative thresholds for mid-to-late haemodynamic and clinical outcomes after pulmonary valve replacement in tetralogy of Fallot. Eur Heart J. 2016;37:829–835. 6. Geva T. Repaired tetralogy of Fallot: the roles of cardiovascular magnetic resonance in evaluating pathophysiology and for pulmonary valve replacement decision support. J Cardiovasc Magn Reson. 2011;13:9. 7. Poynter JA, Eghtesady P, McCrindle BW, Walters HL 3rd, Kirshbom PM, Blackstone EH, et al. Association of pulmonary conduit type and size with durability in infants and young children. Ann Thorac Surg. 2013;96:1695–1702. 8. Joynt MR, Yu S, Dorfman AL, Ghadimi Mahani M, Agarwal PP, Lu JC. Differential impact of pulmonary regurgitation on patients with surgically repaired pulmonary stenosis versus Tetralogy of Fallot. Am J Cardiol. 2016;117:289–294. 9. Bokma JP, Winter MM, Oosterhof T, Vliegen HW, van Dijk AP, Pieper PG, et al. Pulmonary valve replacement after repair of pulmonary stenosis compared with Tetralogy of Fallot. J Am Coll Cardiol. 2016;67:1123–1124. 10. Bautista-Hernandez V, Hasan BS, Harrild DM, Prakash A, Porras D, Mayer JE Jr, et al. Late pulmonary valve replacement in patients with pulmonary atresia and intact ventricular septum: a case-matched study. Ann Thorac Surg. 2011;91:555– 560.
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11. Khanna AD, Hill KD, Pasquali SK, Wallace AS, Masoudi FA, Jacobs ML, et al. Benchmark outcomes for pulmonary valve replacement using the Society of Thoracic Surgeons databases. Ann Thorac Surg. 2015;100:138–146. 12. Karamlou T, Diggs BS, Person T, Ungerleider RM, Welke KF. National practice patterns for management of adult congenital heart disease: operation by pediatric heart surgeons decreases in-hospital death. Circulation. 2008;118:2345–2352. 13. Kogon BE, Plattner C, Leong T, Kirshbom PM, Kanter KR, McConnell M, et al. Adult Congenital Heart Surgery: adult or pediatric facility? Adult or pediatric surgeon? Ann Thorac Surg. 2009;87:833–840. 14. Kirshbom PM, Myung RJ, Simsic JM, et al. One thousand repeat sternotomies for congenital cardiac surgery: risk factors for reentry injury. Ann Thorac Surg. 2009;88:158–161. 15. Morales DL, Zafar F, Arrington KA, et al. Repeat sternotomy in congenital heart surgery: no longer a risk factor. Ann Thorac Surg. 2008;86:897–902. 16. Boethig D, Goerler H, Westhoff-Bleck M, Ono M, Daiber A, Haverich A, et al. Evaluation of 188 consecutive homografts implanted in pulmonary position after 20 years. Eur J Cardiothorac Surg. 2007;32:133–142. 17. Sarikouch S, Horke A, Tudorache I, Beerbaum P, Westhoff-Bleck M, Boethig D, et al. Decellularized fresh homografts for pulmonary valve replacement: a decade of clinical experience. Eur J Cardiothorac Surg. 2016;50:281–290. 18. Bibevski S, Ruzmetov M, Fortuna RS, Turrentine MW, Brown JW, Ohye RG. Performance of SynerGraft Decellularized Pulmonary Allografts Compared With Standard Cryopreserved Allografts: Results From Multiinstitutional Data. Ann Thorac Surg. 2017;103:869–874. 19. Kwak JG, Lee C, Lee M, Lee CH, Jang SI, Lee SY, et al. Does implantation of larger bioprosthetic pulmonary valves in young patients guarantee durability in adults? Durability analysis of stented bioprosthetic valves in the pulmonary position in patients with Tetralogy of Fallot. Eur J Cardiothorac Surg. 2016;49:1207–1212. 20. Lee C, Park CS, Lee CH, Kwak JG, Kim SJ, Shim WS, et al. Durability of bioprosthetic valves in the pulmonary position: long-term follow-up of 181 implants in patients with congenital heart disease. J Thorac Cardiovasc Surg. 2011;142:351–358. 21. Buchholz C, Mayr A, Purbojo A, Glöckler M, Toka O, Cesnjevar RA, et al. Performance of stented biological valves for right ventricular outflow tract reconstruction. Interact Cardiovasc Thorac Surg. 2016;23:933– 939. 22. Chen XJ, Smith PB, Jaggers J, Lodge AJ. Bioprosthetic pulmonary valve replacement: contemporary analysis of a large,
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