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July 2, 1973

Cannabis and the Cardiovascular System

JAMA. 1973;225(1):58. doi:10.1001/jama.1973.03220280046015

Though the primary target of addictive psychoactive substances is the brain, the heart does not always remain unmolested. It may become involved directly, as in alcohol cardiomyopathy, or indirectly, as in bacterial endocarditis of heroin addicts. Evidence is accumulating that even marihuana, which causes no apparent cardiac distress, does not spare the heart.

In a study of cardiovascular effects of marihuana, Beaconsfield and co-workers1 observed the responses of six nonaddicts to smoking one cigarette containing tetrahydrocannabinol, the major active compound present in cannabis, in doses equivalent to those used by habitual smokers. They noted an increase in pulse rate and limb blood flow—responses that could be still provoked after administration of atropine, but not after pretreatment with propranolol. Tetrahydrocannabinol potentiated the tachycardia induced by atropine or epinephrine. Concluding that the cardiovascular effects of marihuana are probably mediated by the beta-adrenergic mechanisms, these investigators urge caution in the use of