Impact of Vascular Adaptation to Chronic Aortic Regurgitation on Left Ventricular Performance

Abstract

Background-This investigation was designed to test the hypothesis that vascular adaptation occurs in patients with chronic aortic regurgitation to maintain left ventricular (LV) performance. Methods and Results-Forty-five patients with chronic aortic regurgitation (mean age 50Ϯ14 years) were studied using a micromanometer LV catheter to obtain LV pressures and radionuclide ventriculography to obtain LV volumes during multiple loading conditions and right atrial pacing. .01, respectively), although the slopes of these relationships differed (PϽ0.05). The average LV work was maximal in Group IIa when the left ventricular-arterial coupling ratio was near 1.0 because of a significant decrease in total arterial elastance (PϽ0.01 versus Group I). In contrast, the decrease in the left ventricular-arterial coupling ratio in Group IIb was caused by an increase in total arterial elastance, effectively double loading the LV, contributing to a decrease in LV pump efficiency (PϽ0.01 versus Group IIa and PϽ0.001 versus Group I). Conclusions-Vascular adaptation may be heterogeneous in patients with chronic aortic regurgitation. In some, total arterial elastance decreases to maximize LV work and maintain LV performance, whereas in others, it increases, thereby double loading the LV, contributing to afterload excess and a deterioration in LV performance that is most prominent in those with impaired contractility.

Arterial elastance and heart-arterial coupling in aortic regurgitation are determined by aortic leak severity

“…[13] In this study, 45 patients (aged 50 ± 14 years) were classified into 3 subgroups according to LV contractility (E max ) and ejection fraction (EF). Group I consisted of 24 patients with normal contractility (E max ≥1 mm Hg/mL).…”

“…Group IIa consisted of 10 patients with impaired LV contractility (E max <1 mm g/mL) but normal EF (EF ≥0.5), whereas group IIb (11 patients) had both impaired contractility and EF (EF <0.5). Hemodynamic patient data, as reported by Devlin et al, [13] are given in Table I. Table I.…”

“…Table I. Hemodynamic data as reported by Devlin et al [13] and calculated and estimated computer model parameters for the 3 The lowest R L,ao corresponds to the most severe aortic leak. Compared to Devlin's reported E a (1.50, 0.70 and 1.36 mm Hg/mL for group I, IIa and IIb, respectively), the values we found for E a are somewhat lower.…”

“…It is not clear why our E a , calculated from the reported average values of SV and end-systolic pressure, differ this much from their values. * Calculated directly from data reported by Devlin et al [13] †Assumed fixed values. ‡Estimated values.…”

“…Devlin et al [13] calculated RI from radionuclide LV and right ventricular counts, the latter representing the forward stroke volume. Arterial elastance was calculated as the ratio of end-systolic pressure and stroke volume.…”