Percutaneous Pulmonary Valve Replacement Research Articles

Infective Endocarditis After Transcatheter Pulmonary Valve Replacement Using the Melody Valve

Transcatheter (percutaneous) pulmonary valve (TPV) replacement has emerged as a viable therapy for right ventricular outflow tract conduit dysfunction. Little is known about the incidence, clinical course, and outcome of infective endocarditis (IE) after TPV implant. We reviewed combined data from 3 ongoing prospective multicenter trials to evaluate the experience with IE among patients undergoing TPV replacement using the Melody valve. Any clinical episode reported by investigators as IE with documented positive blood cultures and fever, regardless of TPV involvement, was considered IE. Cases were classified as TPV-related if there was evidence of vegetations on or new dysfunction of the TPV. The 3 trials included 311 patients followed for 687.1 patient-years (median, 2.5 years). Sixteen patients were diagnosed with IE 50 days to 4.7 years after TPV implant (median, 1.3 years), including 6 who met criteria for TPV-related IE: 3 with vegetations, 2 with TPV dysfunction, and 1 with both. The annualized rate of a first episode of IE was 2.4% per patient-year and of TPV-related IE was 0.88% per patient-year. Freedom from TPV-related IE was 97±1% 4 years after implant. All patients were treated with intravenous antibiotics, 4 had the valve explanted, and 2 received a second TPV. There was 1 sepsis-related death, 1 patient died of sudden hemoptysis, and 2 patients developed recurrent IE. Bacterial endocarditis has occurred in all 3 prospective multicenter studies of the Melody valve in North America and Europe. Most cases did not involve the TPV and responded to antibiotics. More data are necessary to understand risk factors in this population.

Transcatheter Pulmonary Valve Replacement: A Current Review

Since first reported in 2000, transcatheter (percutaneous) pulmonary valve (TPV) replacement has become an important tool for the management postoperative right ventricular outflow tract (RVOT) dysfunction in patients with congenital heart disease, either as alternative or adjunct to surgery. Implantation of a pulmonary valve for treatment of RVOT obstruction or pulmonary regurgitation without performing open-heart surgery offers obvious appeal, and short-term results from multiple institutions throughout the world support the effectiveness and safety of this therapy. At present, there are two TPV prostheses available in the U.S.: the Medtronic Melody® valve is available commercially, and the Edwards Sapien® valve is available at limited centers as part of an investigational protocol. Although TPV therapy is likely to have a major impact on the management of postoperative RVOT dysfunction in patients with congenital heart disease or a Ross procedure, the technology is young and there is much that remains to be learned.

Circulation: Cardiovascular Interventions Editors’ Picks

<i>Circulation: Cardiovascular Interventions</i> Editors’ Picks

Percutaneous pulmonary valve replacement after different duration of free pulmonary regurgitation in a porcine model: Effects on the right ventricle

BackgroundFree pulmonary regurgitation (PR) after surgical correction of Tetralogy of Fallot (ToF) with transannular patching can lead to irreversible right ventricular (RV) failure. However, the optimal timing of valve replacement is still debated. Methods and resultsThirty six pigs were included in the study. Twenty one pigs had a bare metal stent placed in the pulmonary annulus inducing free PR and 9 animals served as control. Six animals died prematurely due to procedural complications. The 21 animals were divided into 3 groups with differential duration of PR (1, 2, 3months, respectively) after which PPVR was performed. After 1month with competent valve the animals were euthanized. Cardiac magnetic resonance (CMR) and right heart catheterization were performed serially. Free PR led to severe dilation of the RV in all three groups compared to matched controls (p<0.001). Final RV volume after one month with competent pulmonary valve was modeled. Increase in RV volume from baseline to valve replacement (ΔRV) was the only predictor of RV recovery (p<0.001) and increases in ΔRV beyond 120mL/m2 were predictive of very low probability of recovery. A total of 5 animals did not recover. ConclusionsRecovery of right ventricular function after free PR by treatment with PPVR was successful in the majority of animals. Increases in RV volume during PR were the only predictor of non-recovery after PPVR and duration of PR did not in itself predict treatment success.

Pulmonary valve replacement based solely on right ventricular size is appropriate in the asymptomatic tetralogy patient

Although the long term outcome of patients with repaired tetralogy of Fallot (TOF) is favorable [1], the initial repair to relieve the right ventricular (RV) outflow tract obstruction often results in significant pulmonary regurgitation (PR). PR in the repaired TOF patient is usually well tolerated for long periods of time. The low resistance, high capacitance reservoir of the pulmonary circulation minimizes the actual regurgitant volume in the face of severe PR. However, over time, chronic PR results in volume overloading of the RV [2]. Volume overloading of the RV eventually leads to an increase in right ventricular end diastolic volume (RVEDV), right ventricular end systolic volume (RV-ESV), and RV systolic dysfunction [3]. The ensuing RV dilatation and dysfunction for one predispose the patient to exercise intolerance [4], congestive heart failure, and atrial and ventricular arrhythmias, and may contribute to the incidence of sudden cardiac death [5]. In order to know whether pulmonary valve replacement (PVR) based solely on RV size is appropriate in the asymptomatic tetralogy of Fallot (TOF) patient we will review: 1) the effect of long term PR in patients with repaired TOF; 2) the results and hemodynamic effect of surgical as well as percutaneous PVR; 3) what we know about timing of PVR in these patients; and, finally, 4) the known determinants of morbidity and mortality in repaired TOF patients with severe PR.

Percutaneous pulmonary valve replacement

Each year in the United States more than 4000 newborns are diagnosed with complex congenital heart disease involving right ventricular outflow tract obstruction. Despite advances in surgical techniques with right ventricle to pulmonary artery conduits, progressive conduit failure often occurs within 4–12years. Consequently, the majority of these patients, prior to becoming adults, require 2–4 operations for the right ventricle outflow tract to reverse the adverse ventricular effects of a volume or pressure load. Fortunately, over the past decade, percutaneous pulmonary valve replacement has emerged as a nonsurgical intervention for right ventricle to pulmonary artery conduit failure.Currently, there are two percutaneous pulmonary valves available in the United States with the Edwards SAPIEN™ valve actively enrolling in a Phase II FDA approved clinical trial, and the Medtronic Melody® valve now FDA approved through a Humanitarian Device Exception pathway. In this article, we review indications, technique and outcomes for percutaneous pulmonary valve replacement and compare and contrast the available percutaneous stent valves.

Melody Valve-in-Ring Procedure for Mitral Valve Replacement: Feasibility in Four Annuloplasty Types

The recurrence of regurgitation after surgical mitral valve (MV) repair remains a significant clinical problem. Mitral annuloplasty rings are commonly used in MV repair procedures. The purpose of this study was to demonstrate the feasibility of transvenous valve-in-ring (VIR) implantation using the Melody valve (Medtronic, Minneapolis, MN), which is a valved-stent designed for percutaneous pulmonary valve replacement, and 4 distinct types of annuloplasty ring (AR) in an ovine model. Ten sheep underwent surgical MV annuloplasty ring placement (n=10): CE-Physio, Edwards Lifesciences, Irvine, CA [n=5]; partial ring [n=3]; flexible ring [n=1]; and saddle ring [n=1]). All animals underwent cardiac catheterization, hemodynamic assessment, and Melody VIR implantation through a transfemoral venous, transatrial septal approach 1 week after surgery. Follow-up hemodynamic, angiographic, and echocardiographic data were recorded. Melody VIR implantation was technically successful in all but 1 animal. In this animal a 26-mm partial AR proved too large for secure anchoring of the Melody valve. In the remaining 9 animals, fluoroscopy showed the Melody devices securely positioned within the annuloplasty rings. Echocardiography revealed no perivalvular leak, and angiography revealed no left ventricular outflow tract obstruction, vigorous left ventricular function, and no aortic valve insufficiency. The median procedure time was 55.5 (range, 45 to 78) minutes. This study demonstrates the feasibility of a purely percutaneous approach to MV replacement in patients with preexisting annuloplasty rings, regardless of ring type. This approach may be of particular benefit to patients with failed repair of ischemic mitral regurgitation.

Short-Term Performance of the Transcatheter Melody Valve in High-Pressure Hemodynamic Environments in the Pulmonary and Systemic Circulations

The Melody valve is approved for percutaneous pulmonary valve replacement in dysfunctional right ventricular outflow tracts. The function of this valve when subjected to high-pressure loads in humans is unknown. The aim of this study was to describe the immediate and short-term results of Melody valves implanted in a high-pressure environment. Definitions of a high-pressure system were established for Melody valves implanted in the systemic (ie, aortic or mitral position) and pulmonary (ie, right ventricular outflow tract conduit or tricuspid valve annulus) circulations. Implants in these environments were ascertained from databases of the 5 centers that participated in the US Investigational Device Exemption trial. Thirty implants met the inclusion criteria: 23 pulmonary circulation implants (all in the pulmonary position) systemic circulation implants (5 in the native aortic position, 1 in a left ventricle-to-descending aorta conduit, and 1 in the mitral annulus). All pulmonary circulation implants were performed percutaneously in the catheterization laboratory. A hybrid approach (surgical exposure for transcatheter implant) was used for 4 of the aortic implants. There were no procedure-related deaths. Three patients died of nonprocedure- and nonvalve-related causes. At 1 year, freedom from moderate to severe regurgitation was 100%, and freedom from mild regurgitation was 90%. Freedom from moderate to severe stenosis was 86% at 1 year. Short-term performance of the Melody valve in high-pressure environments is encouraging, with good valve function in all patients.

Percutaneous pulmonary valve replacement: CD133+ tissue-engineered valved stent implantation

Percutaneous pulmonary valve replacement: CD133+ tissue-engineered valved stent implantation

An assessment of the cost of percutaneous pulmonary valve implantation (PPVI) versus surgical pulmonary valve replacement (PVR) in patients with right ventricular outflow tract dysfunction

Background:Percutaneous pulmonary valve implantation (PPVI) using the Melody transcatheter pulmonary valve is a new procedure introduced in 2000 as a less invasive treatment for right ventricular outflow tract (RVOT) dysfunction. The aim of this new procedure is to restore pulmonary valve competence without the need of open-chest operation. By prolonging the conduit lifespan, it delays surgical pulmonary valve replacement (PVR) and it can therefore potentially reduce the number of open-chest interventions over a patient’s lifetime. PPVI has been shown to be feasible and safe and can be performed with a low complication rate.Objectives and Methods:The aim of this study is to assess the cost of PPVI and the cost of surgical pulmonary valve replacement (PVR) in patients with right ventricular outflow tract dysfunction using a cohort simulation model applied to the UK population.Results:The model resulted in an estimate of mean cost per patient of £5,791 when PPVI is unavailable as a treatment option and in an estimate of mean cost per patient of £8,734 when PPVI is available over the 25-year period of analysis. After sensitivity analysis was undertaken the results showed that the mean per patient cost difference in implementing PPVI over 25 years as compared to surgical PVR lies somewhere between £2,041 and £3,913.Limitations:Given the lack of long-term data on treatment progression, the cost estimates derived here are subject to considerable uncertainty, and extensive sensitivity analysis has been used to counter this. Consequently this study is merely indicative of the levels of cost which can be expected in a cohort of 1,000 patients faced with a choice of treatment with PPVI or surgery. It is not a cost-effectiveness study but it helps place current knowledge on short-term benefits into context.Conclusions:As this analysis shows PPVI is associated with a relatively small increase in treatment management costs over a long time period. It is left entirely to the reader to value whether this inferred increase in long-term cost is worthwhile given the known short-term benefits and any personal judgement formed over long-term benefit.

Effects of Chronic Severe Pulmonary Regurgitation and Percutaneous Valve Repair on Right Ventricular Geometry and Contractility Assessed by Tissue Doppler Echocardiography

Pulmonary regurgitation (PR) following repair of right ventricular (RV) outflow obstruction is related to slowly progressive RV dilatation and heart failure and will eventually require surgical intervention, but optimal timing of pulmonary valve replacement is challenging. Tissue Doppler based quantification of RV contractility may offer additional information in the management of these patients. In a porcine animal model free PR was induced by percutaneous stenting of the pulmonary valve orifice (N = 23). After 1, 2, or 3 months of free PR percutaneous pulmonary valve replacement (PPVR) was performed. Tissue Doppler derived measures of global and regional myocardial contractility were obtained by transthoracic echocardiography, and compared to a sham-operated control group (N = 9). Free PR is associated with RV dilatation (RV end-diastolic area increased from 15 ± 3 to 23 ± 7 cm(2) /m(2) , P < 0.0001) and a decrease in RV fractional area change from 62 ± 10% to 57 ± 12%, P = 0.08, with no impact of duration of free PR. The isovolumic acceleration, regional strain, and strain rate were unchanged after free PR and after PPVR. No consistent relation of echocardiographic measures of contractility and response to PPVR could be identified. Echocardiographic measures of RV contractility remained unchanged, despite significant RV remodeling following chronic PR and PPVR persistently induced significant recovery in the majority of the animals. These results may imply that Tissue Doppler based measures of RV contractility may not be sufficiently sensitive to be a suitable adjunct to conventional echocardiography in the follow-up of patients with free PR in order to optimize timing of valve replacement.

Percutaneous pulmonary valve replacement: autologous tissue-engineered valved stents

Percutaneous implantation has already been used clinically and is a great option for treating young patients. The use of autologous tissue-engineered valved stents might solve the problem of degeneration and limited durability of biological heart valves. Porcine pulmonary heart valves and small intestinal submucosa were obtained from a slaughterhouse. The intestinal submucosa was used to cover the inside of the porcine pulmonary valved stents. Endothelial cells (ECs) and autologous myofibroblasts (MFs) were used from carotid artery segments of juvenile sheep. After MF seeding, constructs were placed in a dynamic bioreactor system and cultured for 16 days. After additional EC seeding, tissue-engineered valved stents were percutaneously deployed into the annulus of the pulmonary valve (n = 9). Angiography was performed at implantation and 4-week follow-up. Constructs were analysed radiographically, by post-mortem examination, and microscopically. In all but one case, orthotopic positioning of the stents (n = 6) at the time of implantation and explantation was observed angiographically, macroscopically, and by computer tomography scan and demonstrated normal valve function (n = 7). Gross morphology confirmed excellent opening and closure characteristics of all leaflets after 4 weeks (n = 7). Strong expression of α-smooth muscle actin in neo-interstitial cells and of von Willebrand factor and PECAM-1 in ECs was revealed by immunocytochemistry. Good functioning and morphological characteristics were observed after percutaneous tissue-engineered valved stent implantation with autologous cells. This implantation of autologous tissue-engineered valved stents will become a valid future option in adolescents.

The Role of Cardiac MRI in the Selection of Patients for Percutaneous Pulmonary Valve Replacement

The Role of Cardiac MRI in the Selection of Patients for Percutaneous Pulmonary Valve Replacement

Tetralogy of Fallot: Yesterday and Today

Tetralogy of Fallot (TOF) is a cyanotic congenital cardiac defect that was first described by Stenson in 1672 and later named for Fallot, who in 1888 described it as a single pathological process responsible for (1) pulmonary outflow tract obstruction, (2) ventricular septal defect (VSD), (3) overriding aortic root, and (4) right ventricular hypertrophy. The surgical history of TOF began with the development of the systemic to pulmonary artery shunt (BT shunt) by Blalock, Taussig, and Thomas in 1944. Ten years later complete repair of TOF was performed by Lillehei using cross-circulation and by Kirklin with a primitive cardiopulmonary bypass circuit. Notable contributions by several other surgeons including Bahnson, Ebert, Malm, Trusler, Barratt-Boyes, and Castaneda would lead us into the modern era of surgery. Today, complete repair of TOF is performed before six months of age with low mortality (<2%). In select cases a modified version of the BT shunt is still performed as the initial procedure. Long-term survival rates are excellent (85%-90%). Adult survivors with TOF are an ever-increasing population and may require reintervention, surgically or catheter based. Promising future innovations include percutaneous pulmonary valve replacement, tissue-engineered autologous valves and conduits, and genetic manipulation. This article presents a review of TOF, including the history of surgical treatment, present-day approaches, and long-term outcomes.

Surgical advances in the treatment of adults with congenital heart disease

This article reviews three common abnormalities requiring surgical treatment in adults with congenital heart disease (CHD): Ebstein's anomaly, the failing Fontan, and pulmonary valve disease. As of 2000, more adults than children are alive with CHD. Each year, more of these adults with CHD undergo surgery. Three common operations performed on adults with CHD are surgery for Ebstein's anomaly, Fontan revision, and pulmonary valve replacement (PVR). Recent advances have been made in each of these three operations. Surgery for Ebstein's anomaly can now be offered to older patients at low risk and with good late outcome. The operation includes tricuspid valve repair or replacement and frequent concomitant procedures such as atrial septal defect closure, arrhythmia surgery (the maze procedure), and coronary artery bypass grafting. Fontan conversion involves: conversion of the previously created atriopulmonary connection to a total cavopulmonary artery, extracardiac Fontan; arrhythmia surgery, typically with a modified biatrial maze procedure along with placement of an antitachycardia, dual-chamber pacemaker with steroid-eluting epicardial leads in all patients; and concomitant procedures to treat associated lesions. The need for PVR is increasing for many adults with CHD. In the past, residual defects such as chronic pulmonary regurgitation following repair of tetralogy of Fallot were considered benign. Recent evidence suggests that pulmonary regurgitation causes significant morbidity, producing right ventricular dilatation and dysfunction, exercise intolerance, arrhythmias, and sudden death. Multiple options exist for PVR including several recent developments such as PVR with a man-made polytetrafluoroethylene bicuspid valve and percutaneous PVR.

Percutaneous reimplantation of a pulmonary valved stent in sheep: A potential treatment for bioprosthetic valve degeneration

Percutaneous pulmonary valve replacement has been recently introduced into clinical practice. Patients with transcatheter pulmonary valve replacement will definitely face the problems of valve degeneration. In addition to surgical re-replacement of the degenerated bioprosthetic valves, we studied the replacement of degenerated bioprosthetic valves with transcatheter reimplantation of stent-mounted pulmonary valves. Percutaneous pulmonary valve replacement was first performed in 6 sheep used a homemade valved stent. Two months after the initial procedure, the 6 sheep previously implanted with a valved stent underwent the same implantation procedure of a pulmonary valved stent. Hemodynamic assessment of the bioprosthetic pulmonary valve was obtained by echocardiography immediately post-implant and at 2 months follow-up. All 6 sheep had successful transcatheter stent-mounted pulmonary valve replacement in the first experiment. After 2 months, reimplantation was successful in 5 sheep but failed in 1 sheep because the first valved stent was pushed to the bifurcation of the pulmonary artery by the delivery sheath. Echocardiography confirmed the stents were in the desired position during the follow-up. The remaining 5 sheep with normal valvular and cardiac functionality survived for 3 months after implantation. Transcatheter stent-mounted bioprosthetic pulmonary valve reimplantation is feasible in an animal model and more convenient than open chest reimplantation.

Percutaneous pulmonary valve replacement

Percutaneous pulmonary valve implantation helps in prolonging the lifespan of surgically placed right ventricle-to-pulmonary artery (RV-PA) conduits, and represents a less invasive alternative to repeat open-heart surgery. The clinical indications for treatment match those of surgery. As far as the suitability is concerned, the current ideal substrate is a degenerated RV-PA conduit, because of the presence of a certain degree of calcification that offers a safe anchoring point. So far, patients have been treated with low morbidity and mortality that were further improved with increasing experience. After percutaneous pulmonary valve implantation, patients experience a subjective improvement, mirrored by an objective increase of measured exercise capacity parameters and by reduced RV-PA gradient, regurgitant fraction, and RV volumes. New developments in the experimental field should result in an extension of indications in the future.

Use of a novel valve stent for transcatheter pulmonary valve replacement: An animal study

The goal of this study was to evaluate valvular functionality after transcatheter pulmonary valve replacement in sheep using a novel pulmonary valve stent. Fresh porcine pericardium cross-linked with 0.6% glutaraldehyde was treated with L-glutamine to eliminate glutaraldehyde toxicity and sutured onto a valve ring before mounting on a nitinol stent to construct the pulmonary valve stent. Percutaneous femoral vein transcatheter pulmonary valve replacement was performed with the newly constructed valve stent. Pulmonary valve stents were implanted in 10 healthy sheep (6 males and 4 females) weighing an average of 25.7 +/- 4.1 kg. Color Doppler echocardiography, 64-row computed tomography, and direct catheter examination were used to assess valvular function. Implantation was successful in 8 sheep. Shortly after surgery, all artificial valve stents exhibited normal open and close functionality and no stenosis or insufficiency. Heart rate was slightly elevated at this time, while all other hemodynamic parameters were normal. Six-month follow-up revealed no evidence of valve stent dislocation and normal valvular and cardiac functionality. There was no evidence of stent fracture. Repeated valve stent implantation was well tolerated as indicated by good valvular functionality 2 months postdelivery. The novel pulmonary valve stent described herein can be delivered via percutaneous femoral vein transcatheter implantation and is highly efficacious at 6 months postdelivery. Furthermore, repeated valve stent replacement was successful.

Transcatheter and Transapical Aortic Valve Replacement

Minimally invasive valve replacement is limited to bioprosthetic aortic and pulmonary valves for use in very specific populations of patients. Replacement via trans-catheter and transapical techniques should be used only in patients in whom traditional surgical replacement is deemed an unacceptable risk. Nursing management will focus heavily on care for comorbid conditions because of the high-risk nature of the patients in whom these valves will initially be implanted.

Intracardiac echocardiography during percutaneous pulmonary valve replacement

The patient is a 26-year-old female with a history of tetralogy of Fallot with severe obstruction of the right ventricular outflow tract (RVOT), and she was operated during the first few months of life with the insertion of an aorto-pulmonary shunt (BTS); in 1986, a valved conduit (Jonescu-Shiley 20) was inserted between the right ventricle and the pulmonary artery. She developed …