Percutaneous Pulmonary Valve Implantation: Current Status and Future Perspectives

Pretranscatheter and Posttranscatheter Valve Planning with Computed Tomography

The range of potential transcatheter solutions to valve disease is increasing, bringing treatment options to those in whom surgery confers prohibitively high risk. As the range of devices and their indications grow, so too will the demand for procedural planning. Computed tomography will continue to enable this growth through the provision of accurate device sizing and procedural risk assessment.

Finite element modeling with patient-specific geometry to assess clinical risks of percutaneous pulmonary valve implantation

BACKGROUND

Percutaneous pulmonary valve implantation (PPVI) is a non-surgical treatment for right ventricular outflow tract (RVOT) dysfunction. During PPVI, a stented valve, delivered via catheter, replaces the dysfunctional pulmonary valve. Stent oversizing allows valve anchoring within the RVOT, but overexpansion can intrude on the surrounding structures. Potentially dangerous outcomes include aortic valve insufficiency (AVI) from aortic root (AR) distortion and myocardial ischemia from coronary artery (CA) compression. Currently, risks are evaluated via balloon angioplasty/sizing before stent deployment. Patient-specific finite element (FE) analysis frameworks can improve pre-procedural risk assessment, but current methods require hundreds of hours of high-performance computation.

METHODS

We created a simplified method to simulate the procedure using patient-specific FE models for accurate, efficient pre-procedural PPVI (using balloon expandable valves) risk assessment. The methodology was tested by retrospectively evaluating the clinical outcome of 12 PPVI candidates.

RESULTS

Of 12 patients (median age 14.5 years) with dysfunctional RVOT, 7 had native RVOT and 5 had RV-PA conduits. Seven patients had undergone successful RVOT stent/valve placement, three had significant AVI on balloon testing, one had left CA compression, and one had both AVI and left CA compression. A model-calculated change of more than 20% in lumen diameter of the AR or coronary arteries correctly predicted aortic valve sufficiency and/or CA compression in all the patients.

CONCLUSION

Agreement between FE results and clinical outcomes is excellent. Additionally, these models run in 2-6 min on a desktop computer, demonstrating potential use of FE analysis for pre-procedural risk assessment of PPVI in a clinically relevant timeframe.

Transcatheter valvular therapies in patients with left ventricular assist devices

Aortic, mitral and tricuspid valve regurgitation are commonly encountered in patients with continuous-flow left ventricular assist devices (CF-LVADs). These valvular heart conditions either develop prior to CF-LVAD implantation or are induced by the pump itself. They can all have significant detrimental effects on patients' survival and quality of life. With the improved durability of CF-LVADs and the overall rise in their volume of implants, an increasing number of patients will likely require a valvular heart intervention at some point during CF-LVAD therapy. However, these patients are often considered poor reoperative candidates. In this context, percutaneous approaches have emerged as an attractive "off-label" option for this patient population. Recent data show promising results, with high device success rates and rapid symptomatic improvements. However, the occurrence of distinct complications such as device migration, valve thrombosis or hemolysis remain of concern. In this review, we will present the pathophysiology of valvular heart disease in the setting of CF-LVAD support to help us understand the underlying rationale of these potential complications. We will then outline the current recommendations for the management of valvular heart disease in patients with CF-LVAD and discuss their limitations. Lastly, we will summarize the evidence related to transcatheter heart valve interventions in this patient population.

First hybrid implantations of novel Salus-Valves in patients with severe pulmonary regurgitation: A case series

With the increasing age of patients after right ventricular outflow tract (RVOT) reconstruction, progressive pulmonary valve (PV) dysfunction can result in different degrees of right heart insufficiency, and PV replacement is frequently needed during follow-up. The traditional redo thoracotomy is difficult and associated with higher risks when compared to transcatheter implantations. Herein, we report the advantages and describe the outcomes of the first hybrid implantations of the novel Salus-Valves (Balance Medical, Beijing, China) from the sub-xiphoid approach in five patients (mean age of 22.6 years) with severe pulmonary regurgitation (PR) after RVOT reconstruction.

Advancing a Bulky Delivery System Using a Novel Technique During Percutaneous Pulmonary Valve Implantation

During percutaneous pulmonary valve implantation, it is challenging to advance the delivery system loaded with a stent-valve through the right ventricular outflow tract. An extra-stiff wire can provide enough supporting and stable positioning to prevent the displacement of the guide wire in stent-valve delivery. In the 2 cases reported here, we used a snare to trap the extra-stiff wire and a large sheath to support the snare; thus, the extra-stiff wire was pulled to the distal end and provided strong support for the advancement of the delivery system. After 8 months of follow-up, the patients were in good condition with excellent valve function. We named this novel, efficient technique the “parallel anchor sheath snare” technique. This report highlights a novel delivery strategy for patients with tortuous right ventricular outflow tracts in percutaneous pulmonary valve implantation.

Role of computed tomography in transcatheter replacement of 'other valves': a comprehensive review of preprocedural imaging

Transcatheter procedures for heart valve repair or replacement represent a valid alternative for treating patients who are inoperable or at a high risk for open-heart surgery. The transcatheter approach has become predominant over surgical intervention for aortic valve disease, but it is also increasingly utilized for diseases of the 'other valves', that is the mitral and, to a lesser extent, tricuspid and pulmonary valve. Preprocedural imaging is essential for planning the transcatheter intervention and computed tomography has become the main imaging modality by providing information that can guide the type of treatment and choice of device as well as predict outcome and prevent complications. In particular, preprocedural computed tomography is useful for providing anatomic details and simulating the effects of device implantation using 3D models. Transcatheter mitral valve replacement is indicated for the treatment of mitral regurgitation, either primary or secondary, and computed tomography is crucial for the success of the procedure. It allows evaluating the mitral valve apparatus, the surrounding structures and the left heart chambers, identifying the best access route and the landing zone and myocardial shelf, and predicting obstruction of the left ventricular outflow tract, which is the most frequent postprocedural complication. Tricuspid valve regurgitation with or without stenosis and pulmonary valve stenosis and regurgitation can also be treated using a transcatheter approach. Computer tomography provides information on the tricuspid and pulmonary valve apparatus, the structures that are spatially related to it and may be affected by the procedure, the right heart chambers and the right ventricular outflow tract.

Preclinical study of a self-expanding pulmonary valve for the treatment of pulmonary valve disease

In the past decade, balloon-expandable percutaneous pulmonary valves have been developed and applied in clinical practice. However, all the existing products of pulmonary artery interventional valves in the market have a straight structure design, and they require a preset support frame and balloon expansion. This shape design of the valve limits the application range. In addition, the age of the population with pulmonary artery disease is generally low, and the existing products cannot meet the needs of anti-calcification properties and valve material durability. In this study, through optimization of the support frame and leaflet design, a self-expanding pulmonary valve product with a double bell-shaped frame was designed to improve the match of the valve and the implantation site. A loading and deployment study showed that the biomaterial of the valve was not damaged after being compressed. Pulsatile flow and fatigue in vitro tests showed that the fabricated pulmonary valve met the hydrodynamic requirements after 2 × 10⁸ accelerated fatigue cycles. The safety and efficacy of the pulmonary valve product were demonstrated in studies of pulmonary valve implantation in 11 pigs. Angiography and echocardiography showed that the pulmonary valves were implanted in a good position, and they had normal closure and acceptable valvular regurgitation. The 180 days' implantation results showed that the calcium content was 0.31-1.39 mg/g in the anti-calcification treatment group, which was significantly lower than that in the control valve without anti-calcification treatment (16.69 mg/g). Our new interventional pulmonary valve product was ready for clinical trials and product registration.

Bicuspidization reconstruction for regurgitant quadricuspid pulmonary valve concomitant pulmonary artery aneurysm graft replacement

Large pulmonary artery aneurysm with severe pulmonary valve regurgitation due to the quadricuspid pulmonary valve (Type F) was found in a 54-year-old woman with fatigue and dyspnea on exertion, and in New York Heart Association (NYHA) functional class III. The annulus plication and bicuspidization technique were successfully used for the pulmonary valvular reconstruction. Then, the main pulmonary artery was replaced with Dacron graft and the left pulmonary arterioplasty was performed. Postoperative echocardiography confirmed a satisfactory motion of the reconstructed pulmonary valve with trivial regurgitation and no stenosis.

[Transcatheter replacement of pulmonary artery valve with a graft containing polytetrafluoroethylene leaflets]

Annually, many operations for repeat prosthetic reconstruction of the pulmonary artery valve are performed due to dysfunction after primary correction of both congenital and acquired heart defects. Open operations with artificial circulation are associated with a high surgical risk. Transcatheter implantation is a new and progressive technique of heart valve replacement. Until recently, implantation of only a biological graft in the position of a pulmonary artery valve was possible, but a limited service life and high risk of the development of infective endocarditis stimulate search for new solutions of this problem. In the he present work we describe cases concerning placement of the first Russian-made valve-containing stent in the position of the pulmonary artery, with the stent's closing mechanism made of polytetrafluoroethylene thus giving ground to count on more favourable results.