EFFECTS OF ORTHOTOPIC CARDIAC TRANSPLANTATION ON STRUCTURAL MICROANGIOPATHY AND ABNORMAL HEMODYNAMICS IN IDIOPATHIC DILATED CARDIOMYOPATHY

To examine whether cardiac transplantation would reverse morphologic a nd hemodynamic changes in peripheral circulation in idiopathic dilated cardiomyopathy, the structure of terminal arterioles and minimal vasc ular resistance were measured in skin at the dorsum of the foot in the same 14 patients before and 80 +/- 21 (mean +/- SD) days and 387 +/- 46 days after transplantation. The results were compared with data fro m a group of 16 healthy subjects. Blood flow was measured by the local technetium-99m pertechnetate washout method in a vascular bed relaxed with histamine. Structural microangiopathy (enhanced thickening of th e basement membranes) in the arterioles was disclosed in skin biopsies in 11 of 14 patients before transplant, but in none of the 16 control subjects (p < 0.002). These abnormalities were unchanged 80 days afte r cardiac transplantation. However, arteriolar wall thickening was sig nificantly reduced over the 1-year period after transplantation (p <0. 05), but this was not complete. Transplantation also led to a signific ant delayed decrease in minimal vascular resistance: before transplant ation, 10.1 +/- 3.2 mm Hg . ml(-1) . 100 g . min (mean +/- SD); 80 day s after transplantation, 9.3 +/- 3.1 mm Hg . ml(-1) . 100 g . min (p = NS), and 1 year after transplantation 7.6 +/- 2.4 mm Hg . ml(-1) 100 g . min (p <0.01). Minimal vascular resistance before and 80 days afte r transplantation was significantly increased compared with that in he althy control subjects (6.3 +/- 1.7 mm Hg . ml(-1) 100 g . min [p<0.00 03 and p<0.003 respectively]). However, 1 year after transplantation; minimal vascular resistance was reduced to comparable levels when comp ared with that in control subjects (p = NS). These results indicate th at structural microangiopathy and minimal vascular resistance in skin are improved slowly and gradually within the first year after orthotop ic cardiac transplantation in patients with idiopathic dilated cardiom yopathy, however, the remodeling of histopathology is not accompanied by complete normalization.