The delayed recovery of impaired endothelium-dependent vasodilatory response after hemodynamic improvement in dogs with congestive heart failure.

We investigated whether impaired endothelium-dependent vasodilatory response recovers as heart failure improves. The femoral blood flow responses to intra-arterial administration of nitroglycerin (NTG) and acetylcholine (ACh) were examined in dogs with 2-week pacing-induced chronic congestive heart failure (congestive heart failure group; CHF, n = 12). Thereafter, pacing was stopped and hemodynamic changes and femoral blood flow responses were re-examined either 1 week (recover 1 week group; Re 1W, n = 6) or 4 weeks (recover 4 weeks group; Re 4W, n = 6) after the cessation of pacing. Another group in which a pacemaker was implanted without pacing served as the control group (n = 8). In CHF, heart rate and pulmonary artery pressure increased, and echocardiography revealed increased left ventricular diastolic dimension and reduced percent fractional shortening compared with those in the control group. In Re 1W, all hemodynamic parameters returned to the basal levels and did not differ from those in the control group. Although there was no significant difference in the blood flow responses to NTG among the 4 groups, the responses to ACh in CHF were significantly reduced compared with those in the control group. Despite the recovered hemodynamics, femoral blood flow responses to ACh were still reduced in Re 1W, but they returned to the levels of the control group in Re 4W. Thus, vascular endothelial dysfunction recovers along with improvement in CHF, however, the recovery of endothelial function is delayed in comparison with improvement in cardiac function.