A 59-year-old man with a history of myocardial infarction 2 years ago undergoes an uneventful aoobifemoral bypass graft for aooiliac occlusive disease. Six hours later he develops ST segment depression, and a 12-lead electrocardiogram (ECG) shows anterolateral ischemia. His hemodynamic parameters are as follows: systemic BP 70/40 mm Hg, pulse 100 beats per minute, CVP 18 mm Hg, PCWP 25 mm Hg, cardiac output 1.5 L/min, and systemic vascular resistance 1000 (dyne * s)/cm5 . Which of the following is the single best pharmacologic intervention for this patient?
This patient has developed pump failure because of a combination of preexisting coronary aery occlusive disease and high preload following a fluid challenge; afterload remains moderately high as well because of systemic vasoconstriction in the presence of cardiogenic shock. Poor myocardial performance is reflected in the low cardiac output and high PCWP. Therapy must be directed at increasing cardiac output without creating too high a myocardial O2 demand on the already failing hea. Administration of nitroglycerin could be expected to reduce both preload and afterload, but, if given without an inotrope, it would create unacceptable hypotension. Nitroprusside similarly would achieve afterload reduction but would result in hypotension if not accompanied by an inotropic agent. A b-blocker would act deleteriously by reducing cardiac contractility and slowing the hea rate in a setting in which cardiac output is likely to be rate-dependent. Dobutamine is a synthetic catecholamine that is becoming the inotropic agent of choice in cardiogenic shock. As a b1 -adrenergic agonist, it improves cardiac performance in pump failure both by positive inotropy and peripheral vasodilation. With minimal chronotropic effect, dobutamine only marginally increases myocardial O2 demand.
Sublingual nitroglycerin
Intravenous nitroglycerin
A sho-acting b-blocker
Dobutamine
Miscellaneous