Effect of therapeutic dosage of lithium on the heart.

1 The cardiac effects of therapeutic levels of lithium were investigated in six healthy male volunteers. Subjects were studied: (1) before lithium ingestion, and (2) when steady-state plasma lithium levels were attained (at least 2 weeks after beginning daily lithium ingestion). 2 A 12-lead electrocardiogram (ECG) and high-speed high-fidelity ECG were used to record electrical activity of the heart. Fractional shortening of the left ventricle using echocardiography, and systolic time intervals (at rest and during exercise), were used as measures of myocardial performance. 3 In this group of healthy volunteers administration of lithium carbonate was associated with a reduction in T wave amplitude in standard electrocardiograms but no statistically significant impairment of myocardial performance.