Effects of orthostatic stress on peripheral capillary filtration in mild congestive heart failure after healing of myocardial infarction.

Patients with heart failure have impaired baroreflex control of the peripheral circulation with attenuated vasoconstrictor response during orthostatic stress. The aim of this study was to test if this impaired baroreflex control not only affects the arterial, but also the capillary bed. Blood flow and capillary filtration were measured in the forearm (plethysmography) in 7 normal subjects and 7 patients with mild congestive heart failure (New York Heart Association functional class II). Measurements were done with the subjects supine and during head-up tilt at 45 degrees. While supine, forearm vascular resistance and capillary filtration coefficient did not differ significantly between the groups. In the control subjects, tilt decreased capillary filtration coefficient by 14 +/- 3% (p < 0.02), and increased forearm vascular resistance by 88 +/- 37% (p < 0.02); in contrast, patients with heart failure had an increase in capillary filtration coefficient of 26 +/- 5% (p < 0.02) and only increased the forearm vascular resistance by 10 +/- 1%, (p = NS, p = 0.26). Our data provide evidence that patients with mild heart failure, in contrast to normal subjects, increase the peripheral capillary filtration during orthostatic stress. The data indicate that impaired baroreflex mechanisms might influence the capillary filtration and it is suggested that impaired baroreflex control of the peripheral circulation can contribute to formation of edema in patients with heart failure.