Non-occlusive, Self-homing Deployment of Durable TAVIs in Compliant Aortic Roots: A Paradigm-Shift for Countries with Limited Access to Cardiac Surgery?

Objective:
As a disease of poverty and poor socioeconomic circumstances, rheumatic heart disease (RHD) is prevalent in the developing world and 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 was 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.

Conclusion:
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.