Which medications in the drug class Catecholamines are used in the treatment of Third-Degree Atrioventricular Block (Complete Heart Block)?

Updated: Jul 05, 2018
  • Author: Akanksha Agrawal, MBBS; Chief Editor: Jeffrey N Rottman, MD  more...
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Catecholamines improve hemodynamics by acting on the beta-adrenergic receptors to increase the HR and contractility and by acting on the alpha-adrenergic receptors to increase the systemic vascular resistance.


Dopamine is a naturally occurring endogenous catecholamine that stimulates beta1- and alpha1-adrenergic and dopaminergic receptors in a dose-dependent fashion; it also stimulates release of norepinephrine.

In low doses (2-5 µg/kg/min), dopamine acts on dopaminergic receptors in renal and splanchnic vascular beds, causing vasodilatation in these beds. In midrange doses (5-15 µg/kg/min), it acts on beta-adrenergic receptors to increase heart rate and contractility. In high doses (15-20 µg/kg/min), it acts on alpha-adrenergic receptors to increase systemic vascular resistance and raise blood pressure (BP).

Norepinephrine (Levophed)

Norepinephrine is a naturally occurring catecholamine with potent alpha-receptor and mild beta-receptor activity. It stimulates beta1- and alpha-adrenergic receptors, resulting in increased cardiac muscle contractility, HR, and vasoconstriction. It increases BP and afterload. The increased afterload may result in decreased cardiac output, increased myocardial oxygen demand, and cardiac ischemia. Norepinephrine is generally reserved for patients with severe hypotension (eg, systolic BP < 70 mm Hg) or hypotension unresponsive to other medication.

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