Cardiac conduction abnormalities produced by chronic alcoholism

Abstract

While conduction disturbances and arrhythmias are seen frequently in alcoholic cardiomyopathy, the specific relationship of these changes to ethyl alcohol has been unclear. To investigate the long-term effects of ethanol upon cardiac conduction, alcoholism was induced in 11 male mongrel dogs for 7 to 33 (mean 14.4) months by feeding up to 36 per cent of total daily calories as ethanol while adequate nutrition was maintained. His and left bundle branch electrograms in the intact anesthetized animals were recorded along with high-speed, high-frequency ECG's. While resting left ventricular pressures, volumes, and stroke outputs were normal, H-Q time was prolonged in the alcoholic animals drinking for longer than one year (35 +/- 3 msec., normals 26 +/- 1 msec.-P less than 0.001). QRS widening (to 80 +/- 4 msec.) was also evident after one year as compared with normals (62 +/- 2 msec.-P less than 0.001), and both H-Q and QRS alterations correlated with duration of intake. These changes were less after shorter ingestion periods, could not be reproduced in normals by acute ethanol infusion, and were not associated with ventricular hypertrophy, inflammation, or necrosis. No abnormalities of atrial conduction were noted. Morphologic correlates of the conduction abnormalities included accumulation of Alcian Blue-positive interstitial material as well as dilatation and localized swelling of the nonspecialized region of the intercalated discs in ventricular muscle and Purkinje fibers. Thus, prolonged ethanol intake in the absence of evident malnutrition resulted in demonstrable intraventricular conduction abnormalities and morphologic alterations which were related to duration of ingestion, consistent with a cumulative toxic effect of ethanol.