Transcatheter heart valve interventions for patients with rheumatic heart disease

Abstract

Rheumatic heart disease [RHD] is the most prevalent cause of valvular heart disease in the world, outstripping degenerative aortic stenosis numbers fourfold. Despite this, global resources are firmly aimed at improving the management of degenerative disease. Reasons remain complex and include lack of resources, expertise, and overall access to valve interventions in developing nations, where RHD is most prevalent. Is it time to consider less invasive alternatives to conventional valve surgery? Several anatomical and pathological differences exist between degenerative and rheumatic valves, including percutaneous valve landing zones. These are poorly documented and may require dedicated solutions when considering percutaneous intervention. Percutaneous balloon mitral valvuloplasty (PBMV) is the treatment of choice for severe mitral stenosis (MS) but is reserved for patients with suitable valve anatomy without significant mitral regurgitation (MR), the commonest lesion in RHD. Valvuloplasty also rarely offers a durable solution for patients with rheumatic aortic stenosis (AS) or aortic regurgitation (AR). MR and AR pose unique challenges to successful transcatheter valve implantation as landing zone calcification, so central in docking transcatheter aortic valves in degenerative AS, is often lacking. Surgery in young RHD patients requires mechanical prostheses for durability but morbidity and mortality from both thrombotic complications and bleeding on Warfarin remains excessively high. Also, redo surgery rates are high for progression of aortic valve disease in patients with prior mitral valve replacement (MVR). Transcatheter treatments may offer a solution to anticoagulation problems and address reoperation in patients with prior MVR or failing ventricles, but would have to be tailored to the rheumatic environment. The high prevalence of MR and AR, lack of calcification and other unique anatomical challenges remain. Improvements in tissue durability, the development of novel synthetic valve leaflet materials, dedicated delivery systems and docking stations or anchoring systems to securely land the transcatheter devices, would all require attention. We review the epidemiology of RHD and discuss anatomical differences between rheumatic valves and other pathologies with a view to transcatheter solutions. The shortcomings of current RHD management, including current transcatheter treatments, will be discussed and finally we look at future developments in the field.

Keywords: aortic stenosis; mitral; regurgitation; rheumatic heart disease; transcatheter intervention.

Figure 1

The pattern of native rheumatic valve disease in 2,475 children and adults with no percutaneous or surgical interventions. AVD, aortic valve disease; MAVD, mixed aortic valve disease; MMAVD, mixed mitral and aortic valve disease; MMVD, mixed mitral valve disease; MR, mitral regurgitation; MS, mitral stenosis from (5). Used with permission.

Figure 2

Level of actually performed cardiac surgery as a percentage of the needs for surgery in the individual country. This data was generated from a study investigating the current state of cardiac surgery in a variety of low- and middle-income countries. It clearly illustrates the dire shortage of access to surgery in Sub-Saharan Africa. The percentages depicted represent mean values thereby masking country-specific social, geographic or political diversities. From (22). Used with permission.

Figure 3

The intrepid transcatheter mitral valve [Medtronic, MN]. Note the double stent design with the outer flexible anchor stent [with small hooks on outside] which isolates the inner valved stent from ventricular compression and therefore may improve durability. Image supplied by Medtronic.

Figure 4

The EVOQUE transcatheter mitral valve [Edwards Lifesciences LLC, Irvine, CA]. Note the anchors that engage the leaflets and subvalvular anatomy to secure placement. This system is designed to treat non-rheumatic mitral valve regurgitation and is not indicated for rheumatic heart disease. Image supplied by Edwards Lifesciences.

Figure 5

Key stages of the deployment of the self-homing, nonocclusive SAT-TAVI valve. Crimped SAT-TAVI system pushed out of the deployment sheath (A), with the locator and stabilizer trunks deployed (B) followed by the full expansion of the scalloped, self-anchoring stent (C) The cobalt-chromium stent is designed to lift up six arms through plastic deformation (D) All arms are seated supra-annularly creating sinus-like outward bulges of the leaflets that firmly anchor the stent in the absence of leaflet calcification. From (91). Used with permission.

Figure 6

The outflow non-occlusive balloon catheter [DISA Medinotec, South Africa]. On the left is a photograph of the device from the side and on the right is an end on view showing 8 smaller balloons arranged in a circular fashion to allow blood flow down the central channel during expansion. This may be more stable during valve deployment without the need for rapid ventricular pacing (96). Pictures supplied by DISA Medinotec.