Microvascular distensibility in two different vascular beds in idiopathic dilated cardiomyopathy

The local isotope-washout technique allows discrimination between blood flow in skin and muscle. Arteriolar constriction, mediated by the sympathetic nervous system, is abolished in a papaverine-histamine-relaxed vascular bed. Microvascular distensibility of relaxed resistance vessels was measured in skeletal muscle and skin of the lower limb in patients with congestive heart failure (CHF) secondary to idiopathic dilated cardiomyopathy and in healthy subjects. Vascular transmural pressure was elevated 40 mmHg by head-up tilt and caused muscle blood flow to increase by 11 +/- 9% in 20 CHF patients compared with 44 +/- 20% in 11 control subjects (P < 0.0003). Also the increase in skin blood flow was significantly reduced: 31 +/- 18% in 42 CHF patients compared with 62 +/- 29% in 25 control subjects (P < 0.001). Regression analysis demonstrated a significant association between microvascular distensibility in skin and skeletal muscle tissue (P = 0.003, r = 0.51, n = 31). Structure of terminal arterioles was determined in skin biopsies, and structural microangiopathy was found in 32 of 42 CHF patients. Multiple regression analysis demonstrated the degree of microangiopathy to be the only parameter significantly associated with microvascular distensibility (P = 0.005, r = 0.42). (There was no association to NY Heart Association functional class, left Ventricular ejection fraction, duration of CHF, age of subject, or mean arterial blood pressure.) We conclude that patients with idiopathic dilated cardiomyopathy have similar decreased microvascular distensibility in skeletal muscle and skin. Furthermore, structural alterations in terminal arterioles seem to be associated with decreased distensibility and increased stiffness of the cutaneous microvascular bed.