Influences of localized aortic valve damage on coronary artery blood flow in acute aortic regurgitation: An experimental study

Abstract

We examined the influences of localized aortic valve damage on coronary artery blood flow and the prognosis in acute aortic regurgitation. Aortic regurgitation was produced in 18 open-chest dogs by extensively cutting one of the three aortic cusps with a nerve knife introduced via the cardiac apex. The dogs were separated into three groups of six dogs each. In each group the noncoronary cusp (NCC), the right coronary cusp (RCC), or the left coronary cusp (LCC) was cut. Aortic and left ventricular pressures; the phasic aortic, left anterior descending (LAD), and right coronary artery (RCA) blood flows; and electrocardiograms were simultaneously recorded before and after production of acute AR. All dogs in the NCC and RCC groups survived for at least 30 to 60 min, but all dogs in the LCC group died after 5 to 9 min of production of acute AR due to left ventricular failure. After 2 min of aortic regurgitation, the total, systolic, and diastolic LAD flows were 39 ± 14, 19 ± 9, and 20 ± 8 ml/min (mean ± SD) in the NCC group, 41 ± 15, 31 ± 9, and 10 ± 6 ml/min in the RCC group, and 9 ± 5, 19 ± 5, and -10 ± 2 ml/min in the LCC group, respectively. The corresponding RCA flows were 19 ± 9, 15 ± 6, and 4 ± 3 ml/min in the NCC group, 13 ± 8, 21 ± 12, and -8 ± 4 ml/min in the RCC group, and 14 ± 4, 19 ± 4, and -5 ± 1 ml/min in the LCC group, respectively. Total LAD and RCA flows decreased significantly after aortic regurgitation in the LCC and RCC groups (p < .001 and p < .05, respectively). Retrograde coronary artery blood flow was observed throughout diastole in the LAD of the LCC group and in the RCA of the LCC and RCC groups. Cardiac output and aortic systolic pressure decreased significantly after production of aortic regurgitation in the LCC group but did not change in the NCC and RCC groups. Aortic end-diastolic pressure was significantly lower in the LCC group than in the NCC and RCC groups after aortic regurgitation. There were no significant differences among the three groups in the regurgitant fraction, cardiac output, left ventricular end-diastolic pressure, aortic systolic pressure, or heart rate. These results suggest that in dogs with acute aortic regurgitation (1) prognosis is remarkably poor when aortic regurgitation is caused by a damaged LCC and (2) left or right coronary blood flow is significantly decreased when the corresponding cusp is damaged.