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Transcatheter therapies for congenital heart disease
- 1. D R NA J E E B U L L A H S O F I L P S I N S T I T U T E O F C A R D I O L O G Y Transcatheter Therapies for Congenital Heart Disease (Cont.)
- 2. Agenda Percutaneous balloonvalvuloplasty 1. Pulmonary Balloon Valvuloplasty 2. Aortic Balloon Valvuloplasty Balloon-Expandable Stenting for Pulmonary Artery Stenosis Transcatheter Pulmonary Valve Replacement
- 3. Pulmonary Balloon Valvuloplasty Pulmonary valve stenosis is a common disorder, accounting for approximately 8% of congenital cardiac defects. Except for neonates with critical pulmonary stenosis, patients with untreated pulmonary valve stenosis often survive well into adulthood. However, when more than mild obstruction to right ventricular (RV) outflow is present, pulmonary valve stenosis should be relieved to prevent progression of obstruction, RV hypertrophy, myocardial fibrosis, and dysfunction. Left untreated, significant pulmonary valve stenosis eventually produces clinical symptoms such as fatigue, dyspnea, and exercise intolerance. These long-term sequelae can be avoided if pulmonary valve stenosis is treated in childhood. Nevertheless, treatment is indicated at any age if hemodynamically significant pulmonary stenosis is documented.
- 4. In congenitalpulmonary valve stenosis, the valve leaflets are thickened and the commissures are fused to varying degrees. Pulmonary valve dysplasia often occurs as a familial trait or as part of Noonan syndrome. A dysplastic pulmonary valve is characterized by thick, cartilaginous valve leaflets with poor mobility. The pulmonary valve annulus is often hypoplastic, and there may be little or no commissural fusion. In isolated pulmonary valve stenosis, balloon dilation reduces the degree of valvular obstruction by separating fused commissures or by tearing the valve leaflets themselves. Patients with severe pulmonary valve dysplasia with hypoplasia of the annulus and absence of commissural fusion may have minimal improvement after balloon valvuloplasty. However, because a spectrum of pulmonary valve dysplasia exists, some patients with this disorder may derive substantial benefit from the balloon valvuloplasty procedure.
- 5. Indications The currentrecommendations for performing balloon pulmonary valvuloplasty are as follows: 1. Critical pulmonary stenosis, defined as pulmonary stenosis in a cyanotic infant requiring a PDA to provide adequate pulmonary blood flow. 2. Resting catheterization peak systolic ejection gradient or echocardiographic peak instantaneous pressure gradient 40 mm Hg or greater. 3. Resting catheterization or echocardiographic gradient less than 40 mm Hg in the setting of RV dysfunction or symptoms.
- 6. Technique Transfemoral venousapproach. A balloon valvuloplasty catheter is used whose inflated balloon diameter is approximately 15% to 25% larger than the pulmonary valve annulus diameter. Balloon oversizing improves valvuloplasty effectiveness, and injury to the pulmonary valve annulus is unlikely when balloons smaller than 140% of the annulus’s diameter are used. If the pulmonary valve annulus exceeds 25 mm or if the single-balloon catheter required is too large for safe introduction into a patient’s femoral vein, we recommend a double-balloon technique, with two balloons positioned across the valve and inflated simultaneously.
- 7. The effectivedilating diameter of two equal-sized balloons can be calculated based on cross-sectional area or on circumference. The sum of the balloon diameters by the circumference method is 120% of the equivalent single- balloon diameters, and by the area method it is 130%. Therefore the operator first selects the optimal single-balloon size, multiplies this diameter by 1.2 or 1.3, and then selects two balloons whose diameters are half of that product. The valvuloplasty balloon or balloons are then inflated by hand until the waist produced by the valve on the balloon disappears. The period of balloon inflation is kept as brief as possible to minimize obstruction to RV outflow. Typically, three or four balloon inflations are performed with minor adjustments in balloon position to ensure adequate dilation of the pulmonary valve.
- 8. Acute Results Thelargest published clinical series of balloon pulmonary valvuloplasty was reported by the Pediatric Valvuloplasty Registry. This registry reported the acute results of pulmonary valvuloplasty performed in 784 patients between 1981 and 1986. Overall, balloon dilation resulted in an acute decrease in the peak systolic pressure gradient from 71 to 28 mm Hg. The residual pressure gradients immediately after valvuloplasty were ascribed in part to subvalvular infundibular obstruction related to RV hypertrophy. Effectiveness of the procedure was not related to age (the series included 35 adults older than 21 years), but a larger residual gradient was observed in patients with a dysplastic pulmonary valve.
- 9. Congenital CardiacCatheterization Project on Outcomes (C3PO), which included 211 cases from eight institutions between 2007 and 2010. The overall procedural success rate was 91%, with 88% of patients obtaining a reduction in the valve gradient to less than 25 mm Hg. The independent risk factors for procedural failure on multivariate analysis were the presence of supravalvular stenosis and evidence of a dysplastic pulmonary valve. Although the overall rate of adverse events was 12%, most of these were mild; only 3% of patients experienced a more severe adverse event. An important finding of this study was that 6% of neonates and 2% of adults required reintervention.
- 10. Pulmonary valvuloplastyhas been performed successfully in patients as old as 84 years. In most published cases, a single- balloon technique has been used. However, when a 20- to 25-mm- diameter balloon was insufficient, the double-balloon technique has often been necessary. Balloon valvuloplasty appears to be effective even in the oldest patients, in whom valve calcification may be present.
- 11. Long-Term Results Long-termstudies of balloon pulmonary valvuloplasty have confirmed that the benefits of this procedure are durable and comparable to the results of surgical valvotomy. In the Pediatric Valvuloplasty Registry, 16% of patients required reintervention with either repeat valvuloplasty or surgical valvotomy during a follow-up period of 8.7 years. Independent risk factors for a suboptimal late outcome included 1. small valve annulus diameter, 2. higher early residual gradient, 3. smaller ratio of balloon-to-annulus diameter, and 4. earlier year at initial intervention. Pulmonary insufficiency, typically mild to moderate, is a common late complication of balloon pulmonary valvuloplasty and is likely more common in smaller patients at the time of valvuloplasty. The surgical group had significantly more pulmonary valve insufficiency and late ventricular arrhythmias.
- 12. Complications Beyond infancy,percutaneous balloon pulmonary valvuloplasty is a very safe procedure. In the C3PO study of 211 balloon pulmonary valvuloplasty procedures in the current era across several institutions, the overall adverse event rate was 12%, and most of these (79%) were of low severity. Again, neonates were more likely to experience adverse events (19% vs. 6%). In the overall cohort, the most common type of adverse event was transient arrhythmias and conduction abnormalities, which were seen in 5% of patients. There have been no reports of long-term arrhythmias after valvuloplasty. Valvuloplasty may cause injury to the femoral vein, especially when the procedure is performed in infancy. The mild pulmonary valve insufficiency commonly seen after pulmonary valvuloplasty, although perhaps not entirely benign, is rarely of clinical importance and may be less severe than after surgical valvotomy..
- 13. Conclusions and Recommendations Percutaneous balloon pulmonary valvuloplasty is the treatment of choice for children and adults with isolated congenital valvular pulmonary stenosis. Valvuloplasty successfully reduces significant RVOT obstruction, with a residual gradient that is usually in the trivial to mild range (i.e., <30 mm Hg). Follow-up studies have documented long-term effectiveness, with little restenosis. Late pulmonary insufficiency is common and may cause RV dilation, but need for pulmonary valve replacement is atypical. Pulmonary valvuloplasty is indicated in neonates with critical pulmonary stenosis and in patients of any age with isolated pulmonary valve stenosis whose resting peak systolic pressure gradient exceeds 40 mm Hg in the presence of a normal cardiac output.
- 14.
- 15. Aortic valvestenosis accounts for 4% to 6% of all cases of CHD. Unlike most cases of congenital pulmonary valve stenosis, congenital aortic stenosis tends to progress over time.
- 16. Indications for Intervention The gradient criteria listed are resting peak systolic gradients measured in the catheterization laboratory with the patient sedated. In addition, given the impact of general anesthesia on systemic blood pressure, resting gradients should be obtained under light conscious sedation whenever possible. Aortic balloon valvuloplasty is indicated for Infants with critical aortic stenosis, which is defined as isolated aortic stenosis with either depressed LV systolic function or evidence of ductal dependency to maintain adequate cardiac output. Infants with critical aortic stenosis typically have severe congestive heart failure and shock with profound LV dysfunction. Notably, the gradient across the aortic valve does not reflect the degree of aortic stenosis because of poor ventricular function and low anterograde flow across the aortic valve.
- 17. Indications Children andYoung Adults Resting peak systolic gradient 50 mm Hg or greater. Resting peak systolic gradient 40 mm Hg or greater if there are any symptoms (e.g., anginal chest pain, syncope) or ischemic changes on either resting or exercise electrocardiography (ECG) Resting peak systolic gradient 40 mm Hg or greater without symptoms or ischemic ECG changes in a patient who plans to become pregnant or to participate in competitive sports. Resting peak systolic gradient less than 50 mm Hg in heavily sedated or anesthetized patients if the echocardiographically derived mean gradient is more than 50 mm Hg
- 18. Technique Percutaneous aorticvalvuloplasty is usually performed from a retrograde transarterial approach, although the antegrade transseptal approach can also be used. In infants, alternative approaches include the carotid artery and the umbilical artery. This diameter is based on the aortic valve annulus diameter, which can be measured by echocardiography or by angiography. Typically, the balloon diameter is 90% to 100% of the aortic valve diameter. Unlike pulmonary balloon valvuloplasty, oversized balloons are not used for aortic valvuloplasty because they have been shown to increase the risk of injury to the aortic valve and annulus. The single-balloon technique, as opposed to the double-balloon technique (which requires two arterial access points) is chosen primarily after consideration of the femoral arterial size to minimize the risk of femoral arterial injury.
- 19. A double-balloontechnique is rarely needed until the aortic annulus is larger than 25 mm. The balloon or balloons are inflated until the waist produced on the balloon by the valve is relieved. Balloon inflation is kept as brief as possible to minimize arterial hypotension during the procedure. To minimize balloon movement during inflation, which has been suggested to cause increased aortic insufficiency during valvuloplasty, rapid ventricular pacing may be performed via a venous access site to temporarily lower stroke volume. A recent randomized trial comparing results of valvuloplasty with or without rapid ventricular pacing in older adults with degenerative aortic valve disease did not demonstrate any immediate difference in the degree of aortic insufficiency.
- 20. Newborn Critical AorticStenosis In newborns with critical aortic stenosis, prostaglandin E1 infusion is initiated to maintain patency of the ductus arteriosus and support cardiac output. Intravenous inotropic support, and occasionally extracorporeal membrane oxygenation support, may be required to stabilize the patient before the procedure. Often, a transumbilical approach is used to spare the infant’s femoral artery (which may be required for future percutaneous valve dilation procedures). The carotid artery and transvenous antegrade approaches have also been reported as means to avoid femoral artery injury in small infants. Carotid is especially useful in low birth weight neonates with critical aortic stenosis. The most challenging aspect of the procedure is often crossing the aortic valve. Special care must be taken to avoid perforation of an aortic valve leaflet (by crossing with a very soft wire), because severe aortic insufficiency due to leaflet tear is poorly tolerated.
- 21. Acute Results Sinceits first description, the effectiveness of balloon valvuloplasty in children and adolescents with congenital aortic valve stenosis has been clearly demonstrated, and the results have proven comparable to those of surgical valvotomy. The Pediatric Valvuloplasty Registry, historically the largest series of balloon aortic valvuloplasty procedures for congenital aortic stenosis, reported the acute results of 630 balloon valvuloplasty procedures in 606 children (age 1 day to 18 years) at 23 institutions between 1984 and 1992. The procedure usually produces an immediate 60% decrease in peak systolic gradient across the aortic valve .The mortality rate was 2.4% and was primarily limited to newborns; there were no deaths in patients older than 3 months of age.
- 22. A recentstudy using data from the National Cardiovascular Data Registry (NCDR) Improving Pediatric and Adult Congenital Treatments (IMPACT) registry showed similar results in a cohort of 1026 patients undergoing isolated balloon aortic valvuloplasty. Successful valvuloplasty, defined as a reduction in the aortic valve gradient to less than 35 mm Hg and mild or less aortic insufficiency, was reported in approximately 71% of patients with noncritical aortic stenosis and approximately 63% in patients with critical aortic stenosis. Interestingly, the overall 30-day mortality rate for the entire cohort was 2.4%, with a much higher rate seen in neonates with critical aortic stenosis, identical to the results from The Pediatric Valvuloplasty Registry.
- 23. Severe aorticregurgitation is uncommon. Vascular complications have been limited primarily to neonates and young infants and have diminished in recent years with the development of lower-profile sheaths and catheters. In the study by Brown and colleagues, a very interesting finding was that patients with residual gradients less than 35 mm Hg and with moderate or severe aortic insufficiency immediately after dilation were no more likely to require late aortic valve replacement than patients with residual gradients greater than 35 mm Hg with mild insufficiency. These data suggest that a more aggressive balloon valvuloplasty to obtain lower residual gradients, even at the cost of creating more aortic insufficiency, may be better for patients in the long term
- 24. The effectivenessof balloon dilation, in terms of both acute success and long- term freedom from reintervention, likely relates to the underlying morphologic substrate. If a technically adequate balloon dilation fails to achieve a satisfactory hemodynamic result in a patient with congenital aortic valve stenosis, a more complex diagnosis is suggested; such patients may be found to have annular hypoplasia or valve leaflet calcification. Most congenitally stenotic aortic valves are bicuspid, involving a single central or eccentric commissure with a variable degree of fusion of its edges. The valve leaflets themselves are thickened but are rarely calcified in childhood. In older patients and in children with prior valve surgery, the leaflets may calcify, becoming less mobile and less amenable to balloon dilation.
- 25. In congenitalaortic valve stenosis, as in pulmonary valve stenosis, balloon valvuloplasty reduces the degree of stenosis by separating valve leaflets along the lines of commissural fusion. In marked contrast, balloon valvuloplasty has proven to be much less successful in older patients with calcific aortic stenosis. In these patients, the aortic valve stenosis is acquired, primarily as a result of calcium deposition within the leaflets, and little or no commissural fusion is present.
- 26. Results in CriticalAortic Stenosis In newborns with critical aortic stenosis, balloon aortic valvuloplasty has proven to be remarkably successful, with results comparable to those of surgical intervention at several premier institutions. The Congenital Heart Surgeons Society reported the results of intervention in 110 neonates with critical aortic stenosis from 18 institutions. Balloon aortic valvuloplasty was the initial procedure in 82 patients and surgical valvotomy in the remaining 28. Relief of aortic stenosis was significantly better in the balloon valvuloplasty group (gradient reduction of 65% ± 17% and median residual gradient of 20 mm Hg vs. 41% ± 32% and 36 mm Hg in the surgical group), although there was also a trend toward more aortic insufficiency in the balloon group. Early mortality was 18%, with no difference between groups. Echocardiographic estimates of valve thickness or mobility have not correlated with valvuloplasty success in neonates.
- 27. Long-Term Results Percutaneousballoon valvuloplasty and all other forms of therapy for congenital aortic valve stenosis should be regarded as palliative therapeutic procedures. As is the case after surgical aortic valvotomy, late restenosis (5 to 20 years) should be expected after a successful balloon dilation procedure.
- 28. The recentstudy by Maskatia and coworkers represents the largest series of patients with 20-year follow-up data. The rate of survival free from any aortic reintervention was 89% at 1 year and steadily declined to 27% at 20 years. Similarly, the rate of survival free from aortic valve replacement was 47% at 20 years. Predictors of reintervention and aortic valve replacement included a higher postvalvuloplasty gradient, whereas a higher grade of acute aortic insufficiency was associated only with shorter time to aortic valve replacement. Long-term mortality was low (88% survival at 20 years), and the highest hazard for death was during the first year after valvuloplasty. These results are similar to what has been found in other long-term follow-up studies.
- 29. Long-Term Results inCritical Aortic Stenosis Neonates with critical aortic stenosis appear to have a substantially higher risk of restenosis and progressive aortic insufficiency after balloon valvuloplasty: 1. reintervention-free survival rate has been approximately 50% at 5 yrs, with 2. aortic valve replacement or surgical repair of aortic insufficiency required in approximately 50% of patients at 10 years.
- 30. Complications Percutaneous balloonaortic valvuloplasty is a relatively safe procedure, and mortality is rare outside of early infancy. Early mortality after balloon valvuloplasty in neonates has ranged from 13% to 18%; l5-year mortality has ranged between 5% and 28%. Other complications reported in the Pediatric Valvuloplasty Registry were rare and included potentially life-threatening arrhythmias, cardiac perforation, and mitral valve injury. A more recently recognized complication of neonatal aortic balloon valvuloplasty is aortic wall injury, in particular the creation of an intimal flap. Because future transfemoral valvuloplasty procedures (for restenosis) are likely to be necessary in these patients, femoral artery access should be preserved if at all possible. Use the transumbilical approach for neonatal critical aortic stenosis if possible.
- 31. Conclusions and Recommendations BAV provides effective palliative treatment for congenital valvular aortic stenosis in infants, children, and young adults. At most pediatric cardiology centers, it is the treatment of choice. Valvuloplasty successfully reduces the peak systolic aortic stenosis gradient to the 20- to 40-mm Hg range, a result that compares favorably with open surgical valvotomy. Aortic insufficiency is not significantly increased in most patients. Mortality is uncommon and has been limited to critically ill neonates and young infants.
- 32. Recommend balloonvalvuloplasty for patients whose: 1. resting peak systolic pressure gradient exceeds 50 mm Hg, for those 2. whose resting peak gradient exceeds 40 mm Hg in association with symptoms or ischemic ECG changes, and for patients with 3. heart failure and low cardiac output regardless of gradient. Balloon valvuloplasty is effective in neonates, children, and young adults with congenital aortic valve stenosis in whom commissural fusion is the primary anatomic cause of outflow obstruction. The procedure is less likely to be effective in patients with a hypoplastic valve annulus or with valve leaflet calcification.
- 33. Balloon-Expandable Stenting for PulmonaryArtery Stenosis
- 34. Balloon-Expandable Stenting forPulmonary Artery Stenosis PA stenosis is encountered as an isolated lesion in patients with arteriopathies such as Williams or Alagille syndrome or as a feature of complex CHD (e.g., TOF) both before and after surgery. Balloon angioplasty of PA stenosis or hypoplasia has yielded mixed results. Numerous reports document an immediate success rate of only 60% to 70% after balloon angioplasty of this lesion, with restenosis rates in follow-up as high as 35%. Failure of angioplasty alone is often related to elastic recoil of the PA. These observations have led to the application of stent therapy to treat PA stenosis or hypoplasia. Since Mullins and colleagues first reported the use of balloon-expandable stents in the PAs and systemic veins in 1988, transcatheter stenting has become the treatment of choice for many patients with PA stenosis and has demonstrated excellent early and long-term effectiveness.
- 35. Technical Considerations PAstenosis is considered significant when 1. the measured gradient across the area of stenosis is greater than 20 to 30 mm Hg, 2. the RV pressure is greater than one-half to two-thirds of systemic pressure due to distal obstruction, or 3. there is relative flow discrepancy of greater than 35%/65% to each lung. When considering stent use in pediatrics, the wide range of patient sizes and the somatic growth over time of the majority of this patient population complicate stent choice in many anatomic positions Implantation of large stents at adult size, or with the potential for redilation to adult size over time, is well accepted, safe, and widely described. However, in infants and small children, stent implantation is often considered more of a palliative option because these stent sizes lack growth potential over time and will require later surgical intervention for transection/removal.
- 36. Despite this,data evaluating PA interventions from a multicenter prospective registry, the C3PO study, found that 46% of all stent implantations used smaller, premounted stents. Use of these stents was more common in younger patients and in nonelective or emergent cases and provides evidence of the relatively widespread use of small- and medium-diameter stents within the pediatric population in current practice. Recently, increasing attention has been focused on intentional stent fracture with ultra- high pressure balloon angioplasty, to create a complete longitudinal fracture to allow a small stent to expand beyond its maximal diameter and accommodate normal vessel growth. In addition, there is currently much ongoing research on biodegradable stents for use in pediatric patients, such that a small stent placed in a child could be thought of as a temporary structure that would degrade over time and could later be replaced by a new larger stent with adult sized potential.
- 37. There areno stents developed specifically for use in pediatric patients with CHD, and therefore the majority of stents used in this setting represent off-label use of coronary and peripheral stents developed for adult purposes. Ideally, large stents, which ultimately can be dilated to a diameter of 18 mm, are appropriate for use in the PAs of a patient who can accommodate the appropriate delivery sheath. In some smaller patients, the internal jugular vein may accommodate a larger sheath than is possible with the femoral venous approach. In addition, a hybrid surgical approach, either with direct stent placement during cardiac surgery or via sternotomy and sheath placement in the main PA, can allow for placement of larger stents in smaller patients. The balloon size chosen for stent implantation is typically up to three times the narrowest vessel dimension, not to exceed the dimension of the adjacent normal vessel.
- 38. Acute and IntermediateOutcomes The largest series of PA stenting in children was reported by McMahon and colleagues in 2002. Over a 12-year period, 664 Palmaz stents were implanted in 338 patients, most with a diagnosis of repaired TOF; the mean age was 12.2 years. After stenting, the systolic pressure gradient across the stenosis decreased from 41 to 9 mm Hg, and the mean diameter of the stented vessels more than doubled. With improved techniques and increased experience, morbidity and mortality decreased significantly during the second half of this series.
- 39. Long-Term Outcomes Thelongest follow-up series was reported in 2009 by Law and colleagues, Their data, with a mean follow-up time of 13.2 ± 2.3 years, confirmed the lasting hemodynamic benefits in these children and documented the feasibility of late stent redilation. Although nonobstructive neointimal proliferation was seen almost universally, clinically important in-stent restenosis was uncommon. Repeated stent dilation in these patients was primarily indicated to accommodate somatic growth. There were no late complications. Despite this and many studies reporting a low rate of late in-stent restenosis, a 2014 study by Hallbergson and coworkers used a more defined criterion for restenosis (>25% narrowing of contrast-filled lumen–to–stent diameter), reported an incidence of 24%. These authors found that patients with TOF who had multiple aortopulmonary collaterals, Williams syndrome, or Alagille syndrome had the highest incidence of in- stent restenosis; no association was found with stent type.
- 40. Conclusions and Recommendations Experimental and clinical data from several centers indicate that balloon- expandable stenting provides an effective form of therapy for many patients with PA stenosis or hypoplasia. Because balloon angioplasty alone is initially unsuccessful in as many as 30% to 40% of patients, stenting is currently considered standard first-line therapy for most children with PA stenosis. If at all possible, implanted stents should have the capacity for later redilation with somatic growth. In infants and small children, in whom larger stents may be difficult to implant due to access site limitations, a hybrid approach for implantation should be considered. If implantation of a small stent is required, an understanding that these stents will require later surgical intervention or intentional fracture is necessary, but this should not preclude the use of stent therapy if clinically necessary.
- 41.
- 42. HISTORY In 2000,Bonhoeffer et al. published the first case report of a tPVR in an ovine model . In this initial report, a fresh bovine jugular vein containing a native biological valve was sewn inside a platinum iridium stent. After being hand crimped onto a balloon catheter, device insertion was attempted via the internal jugular approach in 11 lambs. The device was successfully deployed in seven of the animal models and was in the desired location (native pulmonary valve) in five. The stents were explanted and examined 2 months after implantation. Four out of the five revealed the valves to be mobile and competent, with one valve displaying slight stenosis and macroscopically visible calcification. Only 2 months after the initial animal trial, the first report of implantation of the valve in a human was published by the same group. The patient was a 12-year-old boy with pulmonary atresia and a ventricular septal defect who had an 18-mm Carpentier-Edward valve conduit from the RV to the PA placed at the age of 4 years. He NYHA class II, and echocardiography demonstrated significant stenosis and insufficiency of the conduit, leading to moderate dilatation of the RV. The above-mentioned bovine jugular venous valve was sewn onto a platinum stent and was successfully delivered into the degenerated valve of the conduit via the right femoral vein. There were no procedural complications and postimplantation hemodynamic study demonstrated a reduction in RV pressure. Echo confirmed a competent pulmonary valve with no residual insufficiency.
- 43. Disruption, removal,and replacement of the native pulmonary valve are common to a number of palliative and reparative surgeries for treatment of CHD. Placement of an RV-PA or RVOT conduit is common in surgical palliation of some forms of TOF, transposition of the great arteries, truncus arteriosus, and aortic valve disease treated with the Ross procedure. Even more commonly, in “typical” TOF with pulmonary stenosis, surgical palliation involves enlargement of the pulmonary valve annulus with a transannular patch; this results in long-term pulmonary valve incompetence, which can be associated with late RV dilation and dysfunction. Over the past two decades, there has been increasing clinical emphasis on restoration of pulmonary valve function with pulmonary valve replacement before the development of irreversible RV dilation and dysfunction.
- 44. Patients withsignificant RVOT stenosis (uncommon) or insufficiency (common) after repair of TOF using a transannular patch who have not undergone surgical PVR are increasingly candidates for TPVR. Some centers have recently demonstrated occasional success with TPVR in this population using the Melody TPV, although this approach is limited by the relatively small maximal size of that device. Common long-term limitations to both the RV-PA conduit and BPV include recurrent stenosis and regurgitation. There is strong evidence that such dysfunction can be associated with exercise intolerance, arrhythmias, RV dysfunction, and an increased risk of late sudden death. There is also evidence to show that intervention on a dysfunctional RV-PA conduit or BPV can halt or even reverse the risk of these adverse outcomes. The long-established standard of care for clinically important RV-PA conduit or BPV stenosis or regurgitation is reoperation involving cardiopulmonary bypass and its attendant risks. Such patients face a lifetime of repeat RVOT operations.
- 45. TPVR withinan existing dysfunctional RV-PA conduit or BPV is currently an established and standard-of-care therapy. 1. The goal of this therapy is to prolong the interval between surgical RVOT interventions (either RV-PA conduit or BPV replacement), with the intention to reduce the total number of open heart operations required over the lifetime of a patient. 2. A second goal is to reduce the overall time during which a patient lives with some degree of clinically important RVOT dysfunction (valvular stenosis or insufficiency). TPVR was first introduced in the year 2000 by Bonhoeffer and colleagues. This technology was subsequently acquired by Medtronic (Minneapolis, MN) and marketed as the Melody transcatheter pulmonary valve and the Ensemble delivery system
- 46. Device Melody TPVis currently approved for implantation in the dysfunction RV-PA conduit or BPV. As of June 2018, more than 13,000 Melody valves have been implanted in more than 300 centers worldwide. The Edwards SAPIEN XT transcatheter heart valve has FDA approval for TPVR in the dysfunctional RV-PA conduit. Edwards’ third-generation transcatheter heart valve, the SAPIEN 3, is currently under investigation for TPVR. Once approved, the S3 will be the preferred choice for TPVR given its design improvements over the second- generation valve, adding a skirt to reduce paravalvar leaks and offering a lower profile more flexible delivery system. However, at this point the Edwards’ valves remain unsheathed (uncovered) during delivery across the right heart, which is disadvantageous when crossing the tricuspid valve and existing RVOT hardware
- 47. In theUnited States, there are two FDA-cleared option for TPVR: The Melody TPV is a trileaflet bovine jugular venous valve that has been treated and preserved with glutaraldehyde and sutured into a 34-mm- long platinum-iridium stent . The stent is covered throughout its length by venous tissue. The valve is supplied in two versions: a 20-mm valve, which is indicated for dilation from 18 to 20 mm, and a 22-mm valve for dilation from 18 to 22 mm. With Melody, the diameters refer to the balloon diameter, which is the final valve inner diameter. Experience has suggested that these valves also function well at smaller implant diameters and to be expandable up to 24 mm, but these implant diameters are not listed on the FDA-cleared instructions for use. Melody TPV implantation is performed with the 22-Fr sheathed Ensemble delivery system.
- 49. The SAPIENXT is a trileaflet bovine pericardial tissue valve that has been treated by the “ThermaFix” process and sutured within a cobalt-chromium frame. The valve is available in 23-, 26-, and 29-mm versions (Outer Diameter) and are delivered via the NovaFlex+ deflectable delivery system. With SAPIEN, the diameters refer to the final valve outer diameter.
- 50. Over thelatter half of the past decade, there has been increasing interest in the performance of TPVR within the native (or patch-augmented) RVOT which includes approximately 80% of the overall cohort of patients with postoperative RVOT dysfunction. Although some native RVOT substrate provides an adequate “landing zone” (typically a region of true or relative stenosis) for TPVR with existing balloon- expandable technology, many patients with native RVOT dysfunction have a dilated, large, and dynamic RVOT that will not accept existing commercial valves. To address this potentially rather large CHD population, both Medtronic and Edwards have purpose-built devices in clinical trial.
- 51. The MedtronicHarmony TPV system is a porcine pericardial tissue valve mounted on a novel self-expanding nitinol frame stent with polyester covering, to be deployed via a 25-Fr catheter with retractable sheath. The Edwards Alterra Adaptive Present is an alternative approach to treatment of the dysfunctional native RVOT. Alterra, a novel self-expanding covered nitinol stent, will be delivered by a custom 16-Fr compatible sheathed delivery catheter, and contains a central rigid landing zone. Following placement of this adaptive present, the operator may place a standard 29-mm SAPIEN 3 valve within the Alterra landing zone, to complete a two-step TPVR process.
- 52. Diagnosis & Criteria For RVOT stenosis, Doppler peak systolic gradients lower than 30 mm Hg are considered mild and those between 30 and 50 mm Hg are moderate (in the face of normal RV systolic function). For RVOT insufficiency, cardiac MRI is the imaging modality of choice to quantify RV systolic and diastolic volumes and biventricular systolic function. Intervention is probably indicated for an RVOT with stenosis and/or regurgitation if the RV ejection fraction is diminished or if RV diastolic volume exceeds 160 to 180 mL/m2. Geva and colleagues showed that all patients who had an RV end-systolic volume greater than 95 mL/m2 had evidence of RV dysfunction by MRI.
- 53. AHA classIIa indication for tPVR. It recommends that: “It is reasonable to consider percutaneous pulmonary valve replacement in a patient with an RV-PA conduit with associated moderate-to-severe pulmonary regurgitation or stenosis, provided the patient meets inclusion/exclusion criteria for the available valve (Level of Evidence: B)” The typical criteria used if the patient is asymptomatic include a pulmonary regurgitant fraction of >40%, RV ejection fraction of <40% and an indexed RV end diastolic volume of >150 ml/m2, as determined by cardiac MRI. However, if the patient is symptomatic owing to severe pulmonary regurgitation or stenosis, then such criteria are not strictly enforced. Furthermore, attention to the QRS duration in patients with severe pulmonary regurgitation should be taken into account. A duration of >180 ms is associated with ventricular arrhythmias and sudden death
- 54. Procedural technique 1. Precatheterizationevaluation :- Once the decision has been made that a dysfunctional postoperative RVOT warrants intervention, the feasibility of TPVR must be evaluated. Although TPVR had previously been recommended only for RV-PA conduits that were 16 mm or larger in diameter at surgical implantation, this is no longer an absolute indication. Smaller conduits may be dilated to larger diameter, recognizing that risk of wall disruption exists. Likewise, TPVR is currently being performed in younger and smaller patients in lieu of surgical conduit revision. Valved homograft or heterograft conduits are equally suitable for TPVR. Precatheterization evaluation typically includes cardiac MRI to evaluate the anatomic dimensions of the surgical RVOT, the anatomy of the more distal PA, and the size and function of the RV. Cardiac MRI also can provide valuable information regarding the proximity of the RVOT to the coronary arteries. This is critical information because RVOT rehabilitation before or during valve implantation can occasionally cause coronary artery compression, occasionally with fatal results.
- 55. 2: Vascular access& procedure setup tPVR is performed under general endotracheal anesthesia in the USA. However, in Europe, the procedure has been performed successfully under deep sedation. TPVR is most commonly performed from a femoral venous approach, but the internal jugular venous approach has also been used successfully, as have other central venous and hybrid per-ventricular strategies, when indicated. After baseline hemodynamic measurements are obtained, RV angiography is performed to assess RV function, the anatomy of the RVOT, and the branch PAs; all are important for determining the valve implantation site and the need for concomitant procedures. Aortic root angiography or selective coronary angiography is performed with simultaneous balloon inflation in the RVOT to assess for possible coronary artery compression. .
- 56. 3: Prestenting ExistingRVOT stenosis is typically treated with a combination of serial ultra-high- pressure angioplasty and large-diameter bare-metal stent implantation. Covered large-diameter stent implantation may also be used, following approval of the covered CP stent for aortic and, more recently, RVOT use. General recommendations are to inflate the balloon to a diameter of up to 2 mm less than the original conduit size in stenotic conduits or slightly larger in conduits with no stenosis. It is important to establish that there will be no coronary artery compression with RVOT rehabilitation before the implantation of any stent. Therefore, during balloon angioplasty of the RVOT, the spatial relationship of the RVOT and coronary arteries is assessed with aortography or selective coronary angiography
- 57. Once thepossibility of coronary compression is ruled out, the RVOT is rehabilitated to the desired TPVR implant diameter, with placement of large-diameter bare-metal or covered stents (frequently several telescoped within one another for added radial strength). Early data suggested that inadequate conduit preparation (prestenting) resulted in an increased incidence of TPVR stent fracture and valve dysfunction, prompting a shift in approach to more comprehensive RVOT preparation. An existing BPV, in contrast to an RV-PA conduit, only occasionally requires placement of a preparatory bare-metal stent because the BPV itself typically prevents compressive forces from interacting with the TPV when it is placed in a “valve-in-valve” fashion.
- 58. Results McElhinney andcolleagues reported the short- and medium-term follow-up results from the expanded U.S. Melody valve trial in 136 patients over a period of almost 30 months. This study evaluated the safety, procedural success, and short- and medium- term effectiveness of the Melody valve in patients with dysfunctional RV-PA conduits or BPVs. TPVR was attempted in 124 (91%) of 136 patients; of the remaining 12 patients, TPVR was not attempted in 6 because there was evidence of coronary artery compression during provocative testing. Melody valve implantation was successful in 123 of the 124 attempts (conduit rupture occurred in one patient, necessitating emergent surgical conduit replacement). Among the cohort with a primary TPVR indication of pulmonary stenosis or mixed pulmonary stenosis and pulmonary regurgitation, the median peak RV- PA pressure gradient was acutely reduced from 43.5 to 14 mm Hg.
- 59. Pulmonary regurgitationwas graded as none or trivial in all patients immediately after TPVR. The RV end-diastolic volume, as measured by cardiac MRI, demonstrated substantial reduction at the 6-month follow-up, whereas the RV ejection fraction was not changed. Although medium-term follow-up was limited, no patient had evidence of moderate or severe pulmonary regurgitation at 1 or 2 years of follow-up. Most patients remained in NYHA class I at 2 years. Improvements in cardiopulmonary exercise capacity were modest. Freedom from recurrent RVOT intervention was 95.4% at 1 year and 87.6% at 2 years, which closely matched freedom from valve dysfunction (93.5% and 85.6% at 1 and 2 years, respectively). Ten of the 11 patients requiring RVOT reintervention received transcatheter therapy (90% received a second Melody implant, all in the presence of stent fracture with associated RVOT obstruction).
- 60. Since thattime, investigators have reported the experience with Melody TPV implantation in 120 patients enrolled in the multicenter U.S. postapproval study. In that study, TPV was implanted in 100 patients, with a 98.0% procedural success rate. Acceptable hemodynamic function was found in 96.7% of patients with evaluable data at 6 months. At 1-year follow-up, there were two patients who required surgical conduit replacement, no patients who required catheter-based reintervention, and no pulmonary insufficiency worse than mild. Five-year freedom from TPV reintervention and explantation was 76 ± 4% and 92 ± 3%, respectively. In the patients who were alive and reintervention free, the median follow-up gradient was unchanged from early post-TPV replacement, and all but one patient had mild or less pulmonary regurgitation. Ten-year outcome data are anticipated in the near future. Limited published data exist describing experience with the Edwards Sapien XT valve.
- 61. Complications TPVR hasproven to be safe, with a procedural mortality of less than 0.2%. Acute complications typically relate to RV-PA conduit injury (ranging from mild tear with associated pseudoaneurysm formation to frank conduit rupture with life-threatening hemorrhage), distal guidewire PA injury, or, more commonly, catheterization-related adverse events such as vascular injury or arrhythmia. Coronary artery compression is identifiable during provocative testing and is therefore avoidable, but stent- and valve-related coronary artery compression has been described, occasionally with catastrophic results. Coronary compression can be anticipated in approximately 5% to 6% of TPVR candidates and is more common in patients with abnormal coronary artery anatomy.
- 62. The mostcommon complication in follow-up of Melody TPVR has been Melody stent fracture. In the expanded U.S. experience of 150 patients, freedom from Melody stent fracture was 77% at 14 months and 60% at 39 months, although this study included an early cohort where prestent implantation could not be performed. Among all patients enrolled in North American and European prospective Melody TPV trials, at 3- year follow-up, freedom from any stent fracture and major stent fracture was 74 ± 3% and 85 ± 2%, respectively, and freedom from RVOT reintervention was 85 ± 2%. Placement of a prestent at the TPV implantation procedure was associated with longer freedom from stent fracture and RVOT reintervention than was no prestent. These data have strongly shifted clinical practice toward the placement of RVOT stents before Melody valve implantation. Endocarditis following TPVR is uncommon but not rare and may occur regardless of TPV type implanted. A number of studies have contributed to our understanding of an annualized rate of TPV-related infective endocarditis (IE) of approximately 2% to 3%, reflecting the relatively unprotected position of the TPV in the right heart.
- 63. Conclusion Similar toadvances in transcatheter aortic valve replacement, the availability of TPVR is a remarkable advance for many CHD patients. This technology provides a transcatheter intervention for the dysfunctional RVOT that has the ability to ameliorate both stenosis and regurgitation. Studies have shown that TPVR improves RV hemodynamics and extends the lifespan of the existing RVOT. Currently, a decade in, outcomes data demonstrate excellent effectiveness and low complication rates, with sustained relief of pulmonary stenosis and pulmonary insufficiency. The ongoing hazard of IE remains a considerable risk for patients who will have a biologic prosthesis in place in the RVOT for more than half a century, in many cases.
- 64.