The angiotensin infusion test as a method of evaluating left ventricular function

Effect of angiotensin II infusion on a prostaglandin I2-metabolite and on left ventricular function

Angiotensin II's influence on circulating levels of prostaglandin I2 metabolite 6-keto-PGF1-alpha were determined during a pharmacological stress test of left ventricular function in 10 control subjects and 5 patients with coronary artery disease. Angiotensin II infusion (1.5 +/- 0.34 micrograms/min) led to a significant increase of mean arterial blood pressure in both study groups (p less than 0.001). Heart rate decreased in control subjects (p less than 0.01) whereas in patients with coronary artery disease no significant change occurred. Global left ventricular ejection fraction determined by gated blood pool scanning decreased significantly in both study groups (p less than 0.05). The lack of reflex bradycardia in patients with coronary artery disease may be due to a compensatory increased sympathetic tone, prohibiting a more pronounced decline in ejection fraction. 6-keto-PGF1-alpha levels could be measured only in 6 of 15 persons. In the others they were below the limit of detection of the assay (70 pg/ml). During angiotensin II infusion 6-keto-PGF1-alpha increased significantly and could be determined in all persons. Patients with coronary artery disease reached slightly higher 6-keto-PGF1-alpha levels than controls (119 +/- 19 pg/ml versus 91.5 +/- 7 pg/ml; n.s.). Thus although angiotensin II infusion leads to vasoconstriction and increases peripheral resistance it also stimulates the production of vasodilating prostaglandins which may play a role in preserving microcirculation.

Echocardiographic evaluation of the response to afterload stress test in young asymptomatic patients with chronic severe aortic regurgitation: sensitivity of the left ventricular end-systolic pressure-volume relationship

The detection of myocardial depression is an important goal in the management of patients with chronic severe aortic regurgitation but may be quite difficult at an early stage by the conventional basal measures of contractility. The response to afterload stress determined by angiotensin challenge and the end-systolic pressure-volume relationship was evaluated echocardiographically in 16 asymptomatic or mildly symptomatic patients with chronic severe aortic regurgitation, ages 15 to 56 years (mean 32 +/- 12). Nine normal subjects, ages 25 to 41 years (mean 31 +/- 5), served as a control group. In the group with aortic regurgitation, end-systolic dimensions were greater than 55 mm in five of 16 patients and fractional shortening was 25% or less in two of 16. In the control group angiotensin caused a decrease of stroke volume index in six out of nine patients (15% at the most) and a mild increase in three. In the group with aortic regurgitation stroke volume index decreased by 15% or more of the basal value in nine of 16 patients and increased or decreased by less than 15% in seven of 16. Ejection fraction decreased in both groups, from 61 +/- 6% to 52 +/- 7% in the control group and from 56 +/- 6% to 45 +/- 5% in the group with aortic regurgitation. Ventricular function curves were derived by relating end-diastolic volume index to stroke work index; seven of 16 patients had abnormal responses reflecting an afterload mismatch.(ABSTRACT TRUNCATED AT 250 WORDS)

Depression of heart function after angiotensin II infusion in patients on chronic hemodialysis

The response of heart function to angiotensin II (AT II) was studied in 18 patients on regular hemodialysis. The mean age was 33 years and they had been dialyzed for 55 months in the average. AT II was infused from a large vein and systolic blood pressure was raised by 40 mmHg. Before and after the change in blood pressure, M-mode echocardiogram of left ventricle was recorded. Left ventricular enddiastolic dimension, stroke index and cardiac index were found to be normal except for 9 patients who showed cardiac index above 4.0L/min/m2. No significant change was found in these parameters after the rise of blood pressure by AT II. Control ejection fraction (EF) was slightly but nonsignificantly lower in the patients than the healthy subjects; 0.73 +/- 0.13 vs. 0.80 +/- 0.05. Though significant falls in EF were found in the patient and in the healthy group, the former showed a profound depression of EF to 0.64 +/- 0.10. This value was significantly lower than the value of the latter group; 0.76 +/- 0.04 (p less than 0.01). Since none had overt heart failure, a depression of EF after AT II can be regarded as subclinical abnormality of heart function. AT II will be useful to detect this limited reserve of heart function in patients on regular hemodialysis who may show normal function at rest.

Angiotensin infusion effects on left ventricular function. Assessment in normal subjects and in patients with coronary disease

Radionuclide multigating of the cardiac cycle was employed to assess effects of angiotensin infusion on left ventricular function. In six normal subjects, angiotensin infusion decreased heart rate (HR) from 72 +/- SEM 2 to 57 +/- 2 beats/min (P less than 0.001); while systolic blood pressure (BP) increased from 119 +/- 2 to 178 +/- 1 mm Hg (P less than 0.001), and ejection fraction (EF) declined from 58 +/- 1 to 47 +/- 2 percent (P less than 0.05). In contrast, in 11 normal subjects, supine exercise increased HR and systolic BP by 55 and 49 percent, whereas EF increased from 64 +/- 1 to 71 +/- 1 (P less than 0.001). In ten patients with CAD, angiotensin infusion produced no change in HR, increased systolic BP by 34 percent, and decreased EF by 11 percent. Angiotensin infusion induced left ventricular depression in normal subjects and in patients with CAD. It cannot substitute for exercise in intervention radionuclide ventriculography.