Pre-clinical Evaluation Of A Non-occlusive Tavi Deployment System For Non-calcific Aortic Valve Disease: A Proof Of Concept Animal Study
Jacques Scherman1, Chima Ofoegbu1, Giuseppe Geldenhuys2, Pete Haw2, Fourie Gildenhuys2, Braden van Breda2, Grant Nelson2, Peter Zilla1.
1University of Cape town, Cape Town, South Africa, 2Strait Access Technologies, Cape Town, South Africa.
OBJECTIVE: As a disease of poverty and poor socioeconomic circumstances, rheumatic heart disease (RHD) is prevalent in the developing world and also in emerging economies. Recent estimates suggest an annual need of 200,000 valve replacements in Africa alone in largely young patients with limited access to cardiac surgery. Inspired by the success of closed mitral valvotomy (CMV) half a century ago, we developed a non-occlusive, self-homing trans-apical delivery system for an ‘easy-to-perform’ trans-catheter aortic valve replacement under suboptimal conditions prevalent in non-industrialized countries.
METHODS: The valve deployment system consisted of a non-occlusive ‘hollow-balloon’ with integrated balloon-based annular location and stabilizer concepts. Gradients across two different sizes (23 and 26mm) of the non-occlusive delivery systems were determined during the deployment of SAT’s polymeric TAVI valve before final deployment tests (n=12) were performed in-vivo using trans-apical access in the sheep model.
RESULTS: The orifice areas for the self-sustaining hollow-balloons were 1.4cm2 and 2.2cm2 for the 23 and 26mm deployment systems, respectively. Successful annular location was achieved in n=9/12 animals (75%) and successful deployment of the SAT-TAVI valves in the optimal position were accomplished in n=7/9 animals (77.8%). The average deployment time (measured from balloon expansion to balloon collapse) was 54.6±11.5 seconds. Correspondingly, the mean gradients during the entire deployment time were 19.4±9.3 mmHg, with peak gradients of 32.0±6.5 mmHg. On transoesophageal echo, the mean annulus size of the compliant aortic roots was measured to be 20.3±2.1mm. Oversizing of 18.7±8.7% was applied in order to assure a firm, non-leaking TAVI seat.
CONCLUSIONS: We could successfully demonstrate the feasibility of non-occlusive, self-homing and root-stabilising transapical deployment systems for trans-catheter aortic valve replacements. In analogy to the successful use of trans-apical CMV by general surgeons in developing countries, transcatheter aortic valve replacement may offer life-saving surgeries for the large number of rheumatic patients who have no access to cardiac surgery.
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