General and pulmonary hemodynamic effects of pure decapeptide angiotensin in normotensive man

Hemodynamics of angiotensin in man

These data demonstrate that in normal subjects, angiotensin II is 10 times as potent as norepinephrine which it resembles hemodynamically. An increase in the systolic pressure is associated with a significant increase in diastolic pressure, an increase in venous pressure, a decrease in heart rate, a slight decrease in cardiac output and a striking increase in total peripheral resistance, a decrease in renal blood flow, decreased glomerular filtration rate, increase in filtration fraction, and slight decrease in urinary volume.

Preliminary studies in patients in shock suggest that angiotensin II is 2 or 3 times as potent as norepinephrine. Continuous administration is not associated with the development of tachyphylaxis, and sloughing of tissues does not occur if there is leakage outside the vein.

Peripheral vascular resistance and angiotensin II levels during pulsatile and non-pulsatile cardiopulmonary bypass

The effects of pulsatile and non-pulsatile cardiopulmonary bypass (CPB) on levels of peripheral vascular resistance and plasma angiotensin II (AII) have been studied in 24 patients submitted to elective cardiac surgical procedures. Twelve patients had conventional non-pulsatile perfusion throughout the period of CPB (non-pulsatile group), while 12 had pulsatile perfusion during the central period of total CPB, using the Stockert pulsatile pump system (pulsatile group). There were no significant differences between the groups in respect of age, weight, bypass time, cross-clamp time, or in mean pump flow or mean perfusion pressure at the onset of CPB. Peripheral vascular resistance index (PVRI) and plasma AII levels were measured at the onset of total CPB and at the end of total CPB. In the non-pulsatile group PVRI rose from 19.6 units to 29.96 units during perfusion. In the pulsatile group PVRI showed little change from 20.89 units to 21.45 units during perfusion (P less than 0.001). Plasma AII levels (normal less than 35 pg/ml) rose during perfusion from 49 pg/ml to 226 pg/ml in the non-pulsatile group. The rise in the pulsatile group from 44 pg/ml to 98 pg/ml was significantly smaller than that in the non-pulsatile group (P less than 0.01). These results indicate that pulsatile cardiopulmonary bypass prevents the rise in PVRI associated with non-pulsatile perfusion, and that this effect may be achieved by preventing excessive activation of the renin-angiotensin system, thus producing significantly lower plasma concentrations of the vasoconstrictor angiotensin II.