drugs for cardiac shock
Dobutamine
Dobutamine is a synthetic catecholamine that predominately binds to β-adrenergic receptors and enhances myocardial contractility with minimal changes in heart rate. It is often used in treatment of cardiogenic shock following myocardial infarction to support myocardial contractility while reducing peripheral resistance.
Dopamine
Dopamine is an endogenous catecholamine that is released into the circulation and acts by binding to α1 receptors as well as to specific dopamine receptors in the renal, mesenteric, coronary, and intracerebral vascular beds, causing vasodilation. It has effects that change with increasing doses by binding to different receptors. At low serum concentrations, dopamine binds to dopaminergic receptors in the renal and splanchnic beds leading to increased urine output and natriuresis. At modest concentrations, dopamine binds to cardiac β1-adrenergic receptors leading to increased myocardial contractility and increased heart rate. At high doses, dopamine binds to α-adrenergic receptors and causes an increase in blood pressure and peripheral vascular resistance. Dopamine is an effective agent in increasing blood pressure in hypotensive patients with adequate fluid resuscitation.
Epinephrine
Epinephrine is a circulating endogenous catecholamine, released mainly from the adrenal medulla, whose effects are mediated by binding of free circulating hormone to β1 and β2 receptors, with lesser effects on α adrenoreceptors. At low infusion rates the β1-adrenergic effects predominate causing increased heart rate, stroke volume, and contractility. At higher infusion rates, α-adrenergic receptors are stimulated, resulting in an increase in blood pressure and systemic vascular resistance. Prolonged use of high-dose epinephrine is limited by renal and splanchnic vasoconstriction, cardiac dysrhythmias, and increased myocardial oxygen demand.
Epinephrine
Epinephrine is used as a short-term agent given in intravenous boluses during cardiac arrests and in patients with cardiac dysfunction refractory to other agents such as dobutamine.
Nitroglycerin
Nitroglycerin is primarily a venous smooth muscle vasodilator. It is an effective treatment for myocardial ischemia because it diminishes myocardial oxygen demand by reducing excessive preload and ventricular end-diastolic pressure.
Nitroprusside
Nitroprusside is an arterial and venous smooth muscle vasodilator. Continuous infusions of nitroprusside require monitoring of serum thiocyanate levels and arterial pH for cyanide toxicity.
Norepinephrine
Norepinephrine is also endogenously produced, but acts locally through release at nerve synapses. It acts on α-adrenergic and β-adrenergic receptors, resulting in an increase in afterload and glomerular perfusion pressure with preservation of cardiac output. Norepinephrine is associated with increase in urine output in hypotensive, septic patients.
Phenylephrine
Phenylephrine is a pure α-agonist and its use results in increased peripheral vascular resistance and blood pressure. The increase in afterload increases left ventricular work and oxygen demand, and may cause a decrease in stroke volume and cardiac output.
Phenylephrine
Phenylephrine is often used as a first-line agent in the treatment of neurogenic shock (where there is a loss of sympathetic tone) or as a secondary agent for refractory hypotension in the setting of tachycardia which limits increases in other medications such as dopamine.
Norepinephrine and dopamine
are the first-line agents used for septic shock.
Nitroprusside
can be used in severe cardiogenic shock to reduce afterload or to treat severe hypertension.
Dobutamine
is primarily used in patients with cardiogenic shock.
Nitroglycerin
is used to treat acute myocardial ischemia.
