What is the role of dysrhythmia in the pathophysiology of cocaine toxicity?

Updated: Sep 01, 2018
  • Author: Lynn Barkley Burnett, MD, EdD, LLB(c); Chief Editor: Sage W Wiener, MD  more...
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Answer

Cardiovascular effects result primarily from direct actions on the heart and secondarily from effects on the CNS. Central and peripheral adrenergic stimulation results from inhibition of norepinephrine and dopamine reuptake at preganglionic sympathetic nerve endings. By preventing catecholamine reuptake at presynaptic terminals, cocaine causes catecholamine to accumulate at the postsynaptic membranes.

Without presynaptic reuptake, the action of a neurotransmitter on its receptors becomes sustained. Effects of endogenous catecholamines are thereby potentiated, resulting in tachycardia, hypertension, vasoconstriction, and increased myocardial oxygen consumption. Although cocaine-related tachydysrhythmias result primarily from increases in catecholamine levels, the local anesthetic properties of cocaine can impair impulse conduction in the ventricle, providing a substrate for reentrant ventricular dysrhythmias.

People who abuse cocaine may be exposed to toxic levels of circulating catecholamines. In one study, 48 mg of cocaine more than doubled circulating levels of norepinephrine (420 pg/mL increased to 900 pg/mL). [11] However, most cocaine-related dysrhythmic fatalities occur in patients with low or modest levels of cocaine use. This finding suggests that the mechanism of death may be different in long-term cocaine users, in whom sudden death is most likely the consequence of adrenergic effects and long-term catecholamine toxicity.


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