Evaluation of the pressor, cardiac, and renal hemodynamic properties of angiotensin II in man

Clinical Experience With IV Angiotensin II Administration: A Systematic Review of Safety

OBJECTIVE

Angiotensin II is an endogenous hormone with vasopressor and endocrine activities. This is a systematic review of the safety of IV angiotensin II.

DATA SOURCES

PubMed, Medline, Scopus, and Cochrane.

STUDY SELECTION

Studies in which human subjects received IV angiotensin II were selected whether or not safety was discussed.

DATA EXTRACTION

In total, 18,468 studies were screened by two reviewers and one arbiter. One thousand one hundred twenty-four studies, in which 31,281 participants received angiotensin II (0.5-3,780 ng/kg/min), were selected. Data recorded included number of subjects, comorbidities, angiotensin II dose and duration, pressor effects, other physiologic and side effects, and adverse events.

DATA SYNTHESIS

The most common nonpressor effects included changes in plasma aldosterone, renal function, cardiac variables, and electrolytes. Adverse events were infrequent and included headache, chest pressure, and orthostatic symptoms. The most serious side effects were exacerbation of left ventricular failure in patients with congestive heart failure and bronchoconstriction. One patient with congestive heart failure died from refractory left ventricular failure. Refractory hypotensive shock was fatal in 55 of 115 patients treated with angiotensin II in case studies, cohort studies, and one placebo-controlled study. One healthy subject died after a pressor dose of angiotensin II was infused continuously for 6 days. No other serious adverse events attributable to angiotensin II were reported. Heterogeneity in study design prevented meta-analysis.

CONCLUSION

Adverse events associated with angiotensin II were infrequent; however, exacerbation of asthma and congestive heart failure and one fatal cerebral hemorrhage were reported. This systematic review supports the notion that angiotensin II has an acceptable safety profile for use in humans.

Effects of salt loading and haemodilution on the responses of perfused cat kidneys to angiotensin

1. Effects of single intra-arterial injections (0.1-1.0 mug) of angiotensin II have been observed on cat kidneys perfused with heparinized blood from heart-lung circuits.2. Angiotensin II always caused an abrupt decrease in renal plasma flow (R.P.F.) which reached maximum in 1-2 min and lasted over-all for only 3.5-4.0 min. Glomerular filtration rate (G.F.R.) usually and filtration fraction (F.F.) always increased.3. Angiotensin II caused antidiuresis provided that the kidney had not been subjected either to salt loading or to haemodilution within the preceding 3 hr. These pretreatments converted the antidiuretic action of angiotensin into a diuresis.4. Angiotensin II raised the rate of Na excretion, the urinary concentration of Na and the urinary Na/K whether anti-diuretic or diuretic.

Physical examination of venous pressure: a critical review

OBJECTIVE

To explain why investigations of the measurement of central venous pressure (CVP) usually reveal a discrepancy between the clinician's estimate of CVP from physical diagnosis and supine measurement with a catheter. Data from MEDLINE search, personal files, and bibliographies of textbooks on physical diagnosis and cardiology were used.

RESULTS

The most important reasons for this disagreement are the failure to standardize the external reference point used by the clinician to indicate "zero" venous pressure and the failure to recognize that venous pressure often depends on the position of the patient during examination. During physical examination clinicians tend to underestimate the CVP, as measured by a catheter in the same patient positioned supine, especially when the measured value is high. This occurs because the venous pressure of patients with heart failure, in contrast to that of healthy individuals, demonstrates an exaggerated postural fall when the patient is in the more upright positions that are necessary to visualize the elevated neck veins. The cause of this postural instability, increased venoconstriction from sympathetic tone, also helps explain two other physical findings of the jugular veins, the abdominojugular test, and Kussmaul's sign.

CONCLUSIONS

Clinicians should avoid making decisions about degrees of CVP elevation that are imprecise and difficult to reproduce. Instead, they should determine during physical diagnosis merely whether the CVP is elevated. Until further research is done, the best definition of elevated CVP is that of Sir Thomas Lewis-when the top of the external or internal jugular veins is >3 cm of vertical distance above the sternal angle, the CVP is abnormally high.

Response of ovine uterine blood flow to angiotensin II: effect on the fetus

The effect of intravenous infusion of angiotensin II (2 to 200 ng/kg/min) on uterine blood flow and cardiovascular performance was studied in the normotensive, unanesthetized pregnant ewe. With low rates of infusion (2 to 4 ng/kg/min), only a transient increase in uterine blood flow, lasting 1 to 3 minutes, was observed. Higher rates (110 to 200 ng/kg/min) of infusion caused a decrease in uterine blood flow; this decrease was significantly correlated to the dose. Angiotensin II also caused a significant decrease in the maternal heart rate and an increase in mean maternal arterial blood pressure as the rate of infusion was increased. A high rate of infusion resulted in decreased fetal heart rate and PaO2, probably due to a marked reduction in uteroplacental blood flow.

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.

Renal actions of dihydroergocristine and of phentolamine in anaesthetized cats

1. Comparison has been made of the effects of dihydroergocristine (DCS) and phentolamine mesylate (phentolamine) on cardiac and respiratory rates, systemic arterial pressure, renal clearances of creatinine (C(Cr)) and of p-amino-hippuric acid (C(PAH)) and on the secretion of Na and K, in cats under chloralose anaesthesia.2. Phentolamine antagonized vasomotor tone and the pressor effect of circulating noradrenaline to comparable extent. The extent of reduction in urine flow, C(Cr), C(PAH) and Na excretion correlated with the fall in mean arterial pressure. Innervated and denervated kidneys responded similarly. Cardiac and respiratory rates rose slightly as arterial pressure fell.3. DCS, 10 to 20 mug/kg per min, did not reduce vasomotor tone, markedly reduced the pressor effect of exogenous noradrenaline, caused bradycardia and respiratory slowing but had little or no effect on renal function.4. DCS, 30 to 40 mug/kg per min, lowered mean arterial pressure by 15-25 mm Hg, decreased C(PAH) but not C(Cr), so raising the filtration fraction and caused a small reduction in urine flow and in Na excretion. Innervated and acutely denervated kidneys responded similarly.5. DCS, 30 to 40 mug/kg per min, raised mean arterial pressure, decreased C(PAH), urine flow and Na excretion but did not alter C(Cr) in animals pretreated with full alpha-adrenergic blocking doses of phentolamine.6. DCS, 30 to 40 mug/kg per min, increased the rate of secretion of sympathetic amines from the adrenal medulla and increased the concentration of renin in renal venous blood.7. Isolated kidneys perfused at constant pressure from pump-oxygenator circuits and in saline diuresis responded to DCS (15-17 mug/120 ml. blood) by diuresis and natriuresis and by a rise in the rate of secretion of renin. Higher concentrations of DCS (125-250 mug/120 ml.) were without effect on renal function and did not influence renin secretion.8. The renal effects of full alpha-adrenergic blocking doses of DCS and of phentolamine were comparable, in the whole animal.9. The evidence indicates that the release of noradrenaline by DCS 30-40 mug/kg per min from nerve terminals supplying the juxtaglomerular apparatus may have caused the enhancement of renin secretion.

Some effects of dihydroergocrisine and of phentolamine mesylate on renal function in rats

Single injections of dihydroergocristine (dhe) (25, 50 and 100 μg, i.p.) did not depress the systemic arterial pressure but antagonized the pressor effects of (-)-noradrenaline (100 μg, s.c.) in unanaesthetized rats. The effects of these doses of dhe on water diuresis were minimal: slight K retention, a rise in urinary Na:K and a slight but significant fall in the clearance of p-aminohippuric acid were noted. Single injections of phentolamine mesylate (10, 20 and 40 μg, i.p.) greatly depressed systemic arterial pressure and reduced the glomerular filtration rate and p-aminohippuric acid clearance and the excretion of water and Na proportionately, but markedly. The Na:K in the urine rose. Chemical denervation of the kidneys either with dhe, 32 μg, or phentolamine, 2 mg, thrice daily for 5–7 days decreased, but for 14 days increased, the juxtaglomerular index of the kidneys. Parallel changes were found in the extractable renin. Continued treatment with dhe (32 μg thrice daily for 2 weeks) raised, and hyperduric adrenaline (250 μg twice daily for 1 week) lowered the stores of growth hormone in the adenohypophysis. Continued treatment with dhe, 32 μg thrice daily produced antidiuresis and retention by the third day lasting to the fifth. This condition had reversed by the eighth day.