LEFT-VENTRICULAR REMODELING AND IMPROVEMENT IN FREESTYLE STENTLESS VALVE HEMODYNAMICS

Objective: To assess how left ventricular (LV) hypertrophy, geometry a nd function change after stentless aortic valve replacement for aortic stenosis, and to elucidate the physiological mechanism of the improve ment in stentless valve haemodynamics. Methods: 81 patients with aorti c stenosis (age 75 +/- 6 years, 47 male) underwent aortic valve replac ement (plus CABG in 33 patients) with a Freestyle stentless porcine va lve (mean size 23 +/- 2 mm). They were prospectively investigated by D oppler echocardiography at 2 weeks, 3-6, 12, and 24 months after opera tion. Two hundred and forty-six echocardiograms were obtained and anal ysed. Aortic valve performance was assessed from its effective orifice area (EGA), the transvalvular increase in mean flow velocity (Delta m V), the deceleration time of aortic flow velocity, and mean pressure d rop (mPG). LV hypertrophy was assessed from LV mass index; LV geometry , from the ratio of wall thickness to the radius (T/R ratio) and LV fu nction, from stroke volume index (LVSVI) and myocardial stroke work (S W). Results: By 2 years after operation, LV mass index had fallen from 162 +/- 64 to 109 +/- 36, g/m(2), and T/R ratio from 0.61 +/- 0.25 to 0.43 +/- 0.10. LVSVI increased from 29.4 +/- 10 to 42 +/- 17, ml/m(2) , and myocardial SW from 3.1 +/- 1.6 to 5.2 +/- 2.2, mJ/cm(3) (all P < 0.001 by ANOVA), while LV outflow tract diameter remained unchanged. At the same time, stentless valve EOA increased from 1.59 +/- 0.75 to 2.2 +/- 0.72, cm(2), and Delta mV (from 82 +/- 31 to 49 +/- 24, cm/s) and mPG (from 9.7 +/- 5.0 to 5.2 +/- 3.7 mmHg) both fell significantly (all P < 0.001 by ANOVA); as the deceleration time of aortic flow vel ocity increased from 153.6 +/- 64.1 to 202.7 +/- 37.6 ms (P < 0.001 by ANOVA). Conclusion: After stentless aortic valve replacement, LV mass index and wall thickness both fall towards normal, and myocardial str oke work increases. These ventricular remodelling processes are accomp anied by a more physiological flow jet at valve cusp level, which perm its a greater stroke volume to be ejected with a smaller transvavular velocity increase, so that effective orifice area increases. (C) 1997 Elsevier Science B.V.