Transcatheter aortic valve replacement: Development of an active-flow perfusion system for intracardiac ventricular-arterial bypassing

Objectives: The catheterbased valve implantation received increasing clinical relevance. Problems like paravalvular leakage and embolic events are still unsolved. The experimental isolation and resection of heart valves in a beating heart has already been demonstrated. In this experimental study an active flow perfusion system for intracardiac ventricular-arterial bypass during heart valve isolation was analyzed in porcine hearts.

Material and methods: In the aortic valve isolation chamber (AVIC) system two different active flow concepts were integrated: an intracardiac pump (microaxial, diameter 6.7mm, 5l/min) and an extracardiac pump (Impeller, diameter 6.5mm, 5–10l/min). They were implanted in 10 porcine hearts in a wetlab setup. A roller pump simulated a physiological flow of 4–6l/min. The flow was regulated by a control panel. After transventricular deployment the AVIC pump system was activated. Then the valve was isolated by inflating the sub- and supravalvular balloons. The flow rate through the AVIC was analyzed. The time for deployment and pump activation was documented. A proper valve isolation was confirmed by endoscopy. Gross anatomy was performed after the procedure.

Results: The large size of the devices (max. diameter 20mm) causes difficulties during implantation and positioning. The deployment took 3.4±0.7min. The pump systems generated an AVIC flow with the intracardiac technique of 2–3l/min and an AVIC flow with the extracardiac technique of 4–5l/min during isolation of the aortic valve. No volume overload of the ventricle was observed. After removal groß anatomy showed superficial lesions at the entry site. Intracardial abrasions occured mainly on the ventricular septum.

Conclusion: Intracardiac active flow ventricular-arterial bypassing is possible during heart valve isolation in this in-vitro setup. However major lesions at the entry-site are the most frequent complication. The combination of an AVIC with an active flow perfusion system may generate a sufficient blood flow during transcatheter heart valve replacement in a beating heart. Further development of the system may improve the intervention to make it suitable for in vivo use.