The cardiovascular effects of vasopressin are complex. Its role in various physiological situations is ill-defined. Vasopressin increased blood pressure and systemic vascular resistance and decreased cardiac output, heart rate, and myocardial contractility. Despite the potency of vasopressin as a direct vasoconstrictor, the vasopressin-induced pressor responses are minimal and occur only with concentrations of vasopressin significantly higher than those required for maximal antidiuresis. The potential benefit of vasopressin therapy during CPR was first demonstrated in the animal model.
Consistent results are also present in human studies.
Return of spontaneous circulation was accomplished in all eight patients after vasopressin, although the prognosis was initially poor in all cases. Three patients survived to hospital discharge with minimal or no neurologic deficit. Vasopressin, like other drugs, has some potentially detrimental side effects. Other cardiac complications include arrhythmias and decreased cardiac output. Peripheral vasoconstriction and gangrene have been noted in patients receiving large doses of vasopressin.