EVIDENCE OF INCREASED MICROVASCULAR RESISTANCE AND ARTERIOLAR HYALINOSIS IN SKIN IN CONGESTIVE-HEART-FAILURE SECONDARY TO IDIOPATHIC DILATED CARDIOMYOPATHY

Does nervous microvascular stress from backward cardiac failure and abnormal baroreceptor-mediated vasodilation in the upright position alter the microvascular resistance and structure of the resistance vessels with time? The minimal vascular resistance and structure of the terminal arterioles were measured in skin at the dorsum of the foot in 14 healthy subjects, in 12 patients with short-term congestive heart failure (CHF) (New York Heart Association functional class greater-than-or-equal-to II for < 1 year), and in 14 with long-term CHF (New York Heart Association functional class greater-than-or-equal-to II for > 1 year). Blood flow was measured by the local technetium-99m-pertechnetate washout method in a vascular bed paralyzed by histamine before, during and after 3 to 5 stepwise increases of external counter pressure. Minimal vascular resistance was calculated from the relation between blood flow and applied pressure. Minimal vascular resistance was significantly increased in both short-term (9.0 +/- 1.9 mm Hg.ml-1.100 g.min; p = 0.0003) and long-term (9.1 +/- 3.6 mm Hg.ml-1.100 g.min; p = 0.008) CHF patients compared with that in healthy control subjects (6.0 +/- 1.7 mm Hg . ml-1 . 100 g . min). Structural microangiopathy (increased hyalinosis of the basement membranes in the terminal arterioles) was found in skin biopsies in 21 of 24 patients with CHF in whom biopsies were obtained, but in none of the 14 control subjects (p < 0.002). Multiple regression analysis demonstrated a weak but significant direct association between minimal vascular resistance and the degree of structural microangiopathy (p < 0.03; r = 0.45). These results indicate that microangiopathic alterations in arterioles may contribute to the increased microvascular resistance in patients with CHF.