Sudden cardiac death -- 1978.

With the development of coronary care units in the 1960s, attitudes toward sudden cardiac death (SCD) began to change as physicians learned that cardiac arrest was reversible. The problem of SCD has two aspects an acute, precipitating factor and a chronic predisposition to electrical instability of the myocardium. Resolution of the problem requires identification and protection of the potential victim. Ven- tricular premature complexes (VPCs) have been related to the development of serious arrhythmias and early death, but the mere presence of VPCs does not discriminate risk of subsequent fatality. VPCs should be graded according to frequency, persistence, multiformity, repetitive pattern and degree of prematurity. Provocation of repetitive extrasystoles by R-on-T pacing may indicate the presence of a reduced threshold for ventricular fibrillation (VF). Prophylactic antiarrhythmic therapy may help protect patients resuscitated from VF against recurrent cardiac arrest. Neuropharmacologic factors perhaps affecting central nervous system sympathetic activity can alter cardiac vulnerability and may protect against VF. Findings in dogs indicate that psychologic stress can reduce the cardiac threshold for VF. If psychologic factors predispose to ventricular arrhythmias by increasing the level of sympathetic tone, lessening neural sympathetic activity should reduce the incidence of SCD.