Percutaneous Pulmonary Valve Implantation— Clinical Context

Percutaneous Pulmonary Valve Implantation— Clinical Context For many congenital heart defects treated in infancy (eg, tetralogy of Fallot, transposition of the great arteries, double outlet right ventricle), long-term right ventricular outflow tract (RVOT) dysfunction, in the form of pulmonary stenosis and regurgitation, is a common finding as patients become older (older children, adolescents, and adults). This dysfunction can lead to right ventricular (RV) dilatation, progressive dyspnea, arrhythmia, and sudden cardiac death. Patients are often treated with RV to pulmonary artery (PA) conduits or homograft, which have a finite lifespan and may require replacement every decade or sooner, with pulmonary valve replacement at open-heart surgery. Medical management has a limited role, and although conduit/homograft stenosis can be managed percutaneously with balloon dilatation and bare metal stent insertion to prolong conduit/homograft life, this has the inevitable consequence of inducing free pulmonary regurgitation. During the last decade, however, percutaneous pulmonary valve implantation (PPVI) has been developed to provide a minimally invasive, transcatheter-based approach to prolong conduit/homograft life by treating stenosis and regurgitation without the need for open-heart surgery, thereby reducing procedural risks, hospital stay, and the time it takes to return to normal daily activities. Since the first, pioneering human PPVI in 2000 by Bonhoeffer et al, the technique has gained acceptance, with >4000 procedures performed to date. Several studies have now demonstrated the short-term efficacy of PPVI and defined the potential complications of the procedure, including device migration and fractures, coronary compression, and infective endocarditis. Sustained relief from stenosis and regurgitation has also been demonstrated in the medium term, with freedom from reoperation of 93%, 86%, 84%, and 70% at 10, 30, 50, and 70 months, respectively, with similar freedom from redo interventions 95%, 87%, 73%, and 73% at the same intervals. Survival at 83 months was 96.9% (Figure 1). Short-term data from several studies documented similar complication rates. McElhinney et al reported in 124 patients freedom from reintervention of 93% at 1 year, freedom from stent fracture of 77% at 14 months, 1 death, and 1 explant. Vezmar et al reported in an adolescent cohort freedom from reintervention at 12 and 36 months of 91% and 80%, respectively, and a stent fracture rate of 10.8%. Eicken et al reported in 102 patients 5% stent fracture rate, 1 death because of coronary artery compression, 1 reported episode of endocarditis, 7% reintervention by balloon dilatation, and 4 valve-in-valve procedures. McElhinney et al reported 16 cases of infective endocarditis, with 6 meeting the criteria for transcatheter pulmonary valve endocarditis in a large series of 311 patients, 4 of whom had the replacement valve explanted. This equates to a freedom from prosthetic valve endocarditis of 97% at 4 years after intervention. PPVI has also been demonstrated to be hemodynamically favorable to bare metal stent intervention in the acute setting because it avoids iatrogenic free pulmonary regurgitation after relief of RVOT obstruction. In the medium term, PPVI reduces RV pressure, causes favorable RV remodeling, increases exercise tolerance, and induces electric remodeling, thereby reducing arrhythmic risk. Despite its success, PPVI presents several technical challenges because of the function and anatomy of the RVOT. RVOT, pulmonary trunk, branch PA size, and morphology are unique to each patient, and this morphology is a major determinant of device suitability (Figure 2). The proximity of coronary arteries may also influence device positioning or exclude patients from eligibility. Currently, the Melody PPVI device (Medtronic Inc, MN) is limited to a maximum, 22 mm, whereas the Edwards Sapien PPVI device (Edwards Lifesciences, CA) is available to fit a 26-mm diameter lumen, and thus, device sizing limits suitability in the majority of referred patients (Table 1). This interplay of RVOT morphology and size necessitates detailed preintervention assessment for which we recommend a minimum data set (Table 2).