A new self-expanding aortic stent valve with annular fixation: in vitro haemodynamic assessment

Objective: Balloon-expandable stent valves require flow reduction during implantation (rapid pacing). The present study was designed to compare a self-expanding stent valve with annular fixation versus a balloon-expandable stent valve. Methods: Implantation of a new self-expanding stent valve with annular fixation (Symetis^®, Lausanne, Switzerland) was assessed versus balloon-expandable stent valve, in a modified Dynatek Dalta^® pulse duplicator (sealed port access to the ventricle for transapical route simulation), interfaced with a computer for digital readout, carrying a 25 mm porcine aortic valve. The cardiovascular simulator was programmed to mimic an elderly woman with aortic stenosis: 120/85 mmHg aortic pressure, 60 strokes/min (66.5 ml), 35% systole (2.8 l/min). Results: A total of 450 cardiac cycles was analysed. Stepwise expansion of the self-expanding stent valve with annular fixation (balloon-expandable stent valve) resulted in systolic ventricular increase from 120 to 121 mmHg (126 to 830 ± 76 mmHg)*, and left ventricular outflow obstruction with mean transvalvular gradient of 11 ± 1.5 mmHg (366 ± 202 mmHg)*, systolic aortic pressure dropped distal to the valve from 121 to 64.5 ± 2 mmHg (123 to 55 ± 30 mmHg) N.S., and output collapsed to 1.9 ± 0.06 l/min (0.71 ± 0.37 l/min* (before complete obstruction)). No valve migration occurred in either group. (* = p < 0.05). Conclusions: Implantation of this new self-expanding stent valve with annular fixation has little impact on haemodynamics and has the potential for working heart implantation in vivo. Flow reduction (rapid pacing) is not necessary.