Factors affecting left ventricular remodeling after valve replacement for aortic stenosis. An overview

Abstract

Although a small percentage of patients with critical aortic stenosis do not develop left ventricle hypertrophy, increased ventricular mass is widely observed in conditions of increased afterload. There is growing epidemiological evidence that hypertrophy is associated with excess cardiac mortality and morbidity not only in patients with arterial hypertension, but also in those undergoing aortic valve replacement. Valve replacement surgery relieves the aortic obstruction and prolongs the life of many patients, but favorable or adverse left ventricular remodeling is affected by a large number of factors whose specific roles are still a subject of debate. Age, gender, hemodynamic factors, prosthetic valve types, myocyte alterations, interstitial structures, blood pressure control and ethnicity can all influence the process of left ventricle mass regression, and myocardial metabolism and coronary artery circulation are also involved in the changes occurring after aortic valve replacement. The aim of this overview is to analyze these factors in the light of our experience, elucidate the important question of prosthesis-patient mismatch by considering the method of effective orifice area, and discuss surgical timings and techniques that can improve the management of patients with aortic valve stenosis and maximize the probability of mass regression.

Figure 1

Influence of the relative increase of EOA after AVR on LV mass. Correlation between absolute left ventricular mass (LVM) index regression and increased indexed effective orefice area (r = -0.31; r² = 10%, p = 0.001). (Reprinted from Annals of Thoracic Surgery, Vol. 79, Tasca G et al, Impact of the improvement of valve area achieved with aortic valve replacement on the regression of left ventricular hypertrophy in patients with pure aortic stenosis, Page 1294, © 2005, with permission from The Society of Thoracic Surgery) [19].

Figure 2

Influence of LV histological findings on outcome after AVR. Cumulative survival after the operation in relation to muscle cell nucleus volume. Five- and 7-year survivals were 83 ± 7% and 83 ± 7%, respectively, for a nucleus volume of ≤ 820 μm³ ( ____ ), and 74 ± 10% and 49 ± 14%; respectively, for a nucleus volume of >820 μm³ ( ------ ). (Lund O, et al. Myocardial structure as a determinant of pre- and postoperative ventricular function and long-term prognosis after valve replacement for aortic stenosis. Eur Heart J 1998,19:1099–1108, by permission of Oxford University Press) [42].