Regional blood flow response to orthostasis in patients with congestive heart failure

Abstract

To investigate the central and regional circulatory response to orthostasis in congestive heart failure, hemodynamic variables and forearm and hepatic blood flow were measured in 22 patients at supine rest and during a 65 degrees head-up tilt. Results were compared with those in nine normal subjects. Heart rate and mean arterial blood pressure increased during tilt in normal subjects, but not in patients with heart failure. Forearm blood flow decreased in normal subjects from 3.7 +/- 1.1 to 2.7 +/- 1.5 ml/min per 100 g (probability [p] less than 0.02), but did not change from a lower baseline (1.65 +/- 0.78 ml/min per 100 g) in patients. Forearm vascular resistance increased in normal subjects but not in patients. Hepatic blood flow did not change during tilt in either group, but hepatic vascular resistance increased in normal subjects from 0.37 +/- 0.13 to 0.47 +/- 0.15 U, (p less than 0.02). The increase was not seen in patients (1.2 +/- 1.1 to 1.4 +/- 1.0 U, p = not significant [NS] ). Total systemic resistance increased in patients from 1,848 +/- 560 to 2,132 +/- 731 dynes.s.cm-5 (p less than 0.005) indicating that resistance did increase in some vascular beds. Plasma norepinephrine also increased modestly in these patients from 665 +/- 377 to 761 +/- 379 pg/ml (p = 0.035), but individual changes in plasma norepinephrine did not correlate with changes in hepatic or forearm resistance. Thus, both the overall hemodynamic response and the regulation of regional blood flow and resistance differ in several respects in patients with congestive heart failure when compared with normal subjects. Changes in heart rate, blood pressure, forearm flow and forearm and hepatic vascular resistance are all blunted in patients. Reasons for the differences are not yet clear, but may be associated with abnormalities in reflex control of the circulation in patients with congestive heart failure.