Heterogeneous reduction in regional wall stress after aortic valve replacement for aortic regurgitation: a distinct feature from aortic stenosis.

ABSTRACT

Geometric changes caused by volume reduction early after aortic valve replacement (AVR) for aortic regurgitation (AR) may not be uniform, resulting in varying regional end-systolic wall stress (ESS). This study compared changes in regional ESS between AR and aortic stenosis (AS) patients in the early phase following AVR. Computer-tomographic left ventricular (LV) angiography was performed for 10 patients with AR and 13 with AS before and three months after AVR. Regional ESS at the base, middle, and apex levels, each subdivided into four segments, was calculated based on the Janz equation ESS = end-systolic LV pressure × local cross-sectional area of LV cavity/that of LV wall. Following AVR, median LV end-diastolic volume index fell from 106 to 69 ml/m2 (P = 0.001) in AR and 60 to 46 ml/m2 (P = 0.01) in AS patients. Global ESS also declined in both (AR, 186 to 124 kdyne/cm2, P = 0.02; AS, 187 to 108 kdyne/cm2, P < 0.001, respectively). Regional ESS was reduced in all segments in AS patients, accompanied by left ventricular ejection fraction (LVEF) improvement (71-80%, P = 0.02). In contrast, regional ESS in AR patients was heterogeneously reduced, as regional ESS fell significantly in the antero-septal wall but was unchanged in the infero-lateral wall, and LVEF remained unchanged (65 to 62%, P = 0.42). In the early postoperative phase after AVR, the loading condition of the regional LV wall in AR patients was characterized by a heterogeneous reduction in regional ESS in contrast to a uniform decline in AS patients.