Abstract
1. The purpose of the study was to investigate the effects of angiotensin II on Doppler parameters of right ventricular systolic and diastolic blood flow, and to compare these with effects on the left heart, in normal subjects. 2. Pulsed-wave Doppler measurements were made in eight normal volunteers: after a 30 min control i.v. infusion of dextrose, after 30 min stepwise infusions of angiotensin II (2, 4 and 6 ng kg-1 min-1), and finally 30 min after stopping the 6 ng kg-1 min-1 dose of angiotensin II. Aortic (Ao) and pulmonary (Po) systolic ejection parameters, as well as mitral (Mi) and tricuspid (Tc) diastolic filling parameters were measured. 3. Ao and Po maximal velocity were both significantly reduced by angiotensin II, whereas there were significant opposite effects on Ao (reduced) and Po (increased) mean acceleration. There was a dose-related fall in Po acceleration time with angiotensin II, whilst Ao acceleration time remained unchanged. 4. Mi and Tc early diastolic filling velocities were not significantly altered by angiotensin II compared with baseline, although there was a significant rebound increase in both Mi and Tc early filling after cessation of angiotensin II infusion. Mi and Tc pressure half-times were not significantly changed. 5. In conclusion, angiotensin II produced changes in Po ejection parameters consistent with a pressor response in the pulmonary vascular bed. Neither right nor left ventricular diastolic filling were directly affected by angiotensin II. The differential effects of angiotensin II on Po and Ao ejection parameters might be due to inherent differences in basal pulmonary and systemic vascular tone.