ELECTROCARDIOGRAPHIC CHANGES INDUCED BY AMRINONE IN THE ISOLATED PERFUSED GUINEA-PIG LANGENDORFF HEART PREPARATION

  • 1 January 1983
    • journal article
    • research article
    • Vol. 264  (2) , 263-273
Abstract
ECG changes induced by 3 different concentrations of amrinone were determined in the spontaneously beating guinea pig Langendorff heart preparation. At a concentration of 50 .mu.g/ml, there were no ECG changes except for a sinus tachycardia having a mean increase of 15.64 .+-. 4.0%, (P < 0.01). At a concentration of 250 .mu.g/ml, sinus tachycardia was more evident (+ 20.86 .+-. 1.22%; P < 0.001). There was also a statistically significant shortening of the Q-T interval (P < 0.001). With 1000 .mu.g/ml, amrinone further increased heart rate (+ 45.10 .+-. 13.26%; P < 0.001). There was a greater shortening of the Q-T interval, and occasionally sagging of the S-T segment. Dysrhythmic phenomena including coupled beats, at times with R waves appearing during the vulnerable period of the T wave; ventricular premature beats and alternating polymorphic ECG patterns, were evident. Second and 3rd degree atrioventricular block preceded by marked prolongation of the P-R interval less commonly developed at this concentration. On the basis of these observations and others, it appears that as regards the development cardiotoxicity, amrinone possesses a relatively wide margin of safety not less than 5 and may even approach 20.

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