Aims: Cardiac surgery in middle-income countries differs significantly from that in high-income countries regarding prevailing heart valve pathologies and access to cardiac surgery. Typically, rheumatic aortic regurgitation in the absence of calcification by far outweighs stenosis. As such, entirely different transcatheter aortic valve implantation (TAVI) concepts are required for these regions. The aim of the study was to evaluate the five-month performance of the SAT (Strait Access Technologies, Cape Town, South Africa) pericardial TAVI system in the orthotopic aortic position of juvenile sheep.Methods and results: A self-homing, non-occlusive balloon-expandable TAVI system comprising a hollow balloon, stabilising locator trunks, a scalloped CoCr stent with elevating anchorage arms and decellularised, sandwich-crosslinked pericardium was compared with control surgical valves (Edwards PERIMOUNT) in sheep. The implantation period was five months. The tactile placement of the TAVI valves was accomplished without the need for rapid pacing. At termination, no structural degeneration was observed in either group. The TAVIs were well healed with the stent struts largely embedded in tissue. Correlating with sheep growth (weight gain of 40.4±13.0%) during the implantation period, mean transvalvular gradients increased from 3.08±1.95 mmHg to 8.50±5.38 mmHg (p=0.044) after five months.Conclusions: A single-stage, balloon-expandable, easy to place TAVI system with antigen-depleted and antigen-masked bioprosthetic leaflets promises to address the distinct needs of low-and middle-income countries with regard to TAVI better than conventional systems.

Leaflet durability and costs restrict contemporary trans-catheter aortic valve replacement (TAVR) largely to elderly patients in affluent countries. TAVR that are easily deployable, avoid secondary procedures and are also suitable for younger patients and non-calcific aortic regurgitation (AR) would significantly expand their global reach. Recognizing the reduced need for post-implantation pacemakers in balloon-expandable (BE) TAVR and the recent advances with potentially superior leaflet materials, a trans-catheter BE-system was developed that allows tactile, non-occlusive deployment without rapid pacing, direct attachment of both bioprosthetic and polymer leaflets onto a shape-stabilized scallop and anchorage achieved by plastic deformation even in the absence of calcification. Three sizes were developed from nickel-cobalt-chromium MP35N alloy tubes: Small/23 mm, Medium/26 mm and Large/29 mm. Crimp-diameters of valves with both bioprosthetic (sandwich-crosslinked decellularized pericardium) and polymer leaflets (triblock polyurethane combining siloxane and carbonate segments) match those of modern clinically used BE TAVR. Balloon expansion favors the wing-structures of the stent thereby creating supra-annular anchors whose diameter exceeds the outer diameter at the waist level by a quarter. In the pulse duplicator, polymer and bioprosthetic TAVR showed equivalent fluid dynamics with excellent EOA, pressure gradients and regurgitation volumes. Post-deployment fatigue resistance surpassed ISO requirements. The radial force of the helical deployment balloon at different filling pressures resulted in a fully developed anchorage profile of the valves from two thirds of their maximum deployment diameter onwards. By combining a unique balloon-expandable TAVR system that also caters for non-calcific AR with polymer leaflets, a powerful, potentially disruptive technology for heart valve disease has been incorporated into a TAVR that addresses global needs. While fulfilling key prerequisites for expanding the scope of TAVR to the vast number of patients of low- to middle income countries living with rheumatic heart disease the system may eventually also bring hope to patients of high-income countries presently excluded from TAVR for being too young.

During the past decade transcatheter aortic valve implantation (TAVI) has revolutionized our approach to heart valve disease. Although largely applied to patients with calcific aortic valve stenosis, there is an unmet clinical need to also treat patients with aortic valve insufficiency in patients with non-calcific aortic valve disorders. The following Techno-College tutorial demonstrates our pre-clinical experience with a novel non-occlusive, self-homing TAVI system, developed with Strait Access Technologies, that we hope will improve outcomes for treatment of non-calcific aortic valve insufficiency.