Cardiovascular actions of lead and relationship to hypertension: a review.

Chronic and acute lead poisoning cause overt, clinical symptoms of cardiac and vascular damage with potentially lethal consequences. Morphological, biochemical, and functional derangements of the heart have all been described in patients following exposure to excessive lead levels. Disturbances in cardiac electrical and mechanical activity and postmortem evidence of morphological and biochemical derangements of the myocardium have all been reported following excessive exposure to lead in humans. In addition, signs of vascular degeneration, abnormal vascular smooth muscle function, and altered vessel compliance have been described in humans chronically and acutely exposed to toxic lead levels. Similar cardiovascular complications have been detected following excessive lead exposure in experimental animals. Myocarditis, electrocardiographic disturbances, heightened catecholamine arrhythmogenicity, altered myocardial contractile responsiveness to inotropic stimulation, degenerative structural and biochemical changes affecting the musculature of the heart and vasculature, hypertension, hypercholesterolemia, atherosclerosis, and increased vascular reactivity to alpha-adrenergic agonists have been among the reported cardiovascular disturbances linked to lead poisoning. Less certain are the cardiovascular effects of subclinical lead poisoning. Although controversial, chronic low-level lead exposure has been linked to hypertension and other cardiovascular disturbances in both clinical and experimental studies. In general, it can be concluded that lead over a wide range of exposure intensities can induce significant changes in the function of the cardiovascular system. Evidence points to the involvement of multiple sites of action. Cardiac and vascular sites, as well as sites within the central nervous system, have all been implicated in the sequelae of cardiovascular effects. The exact pathogenic mechanisms that underlie the actions of lead in the cardiovascular system, however, have yet to be elucidated definitively.(ABSTRACT TRUNCATED AT 250 WORDS)