Alterations in the Electrocardiogram of Spontaneously Hypertensive Rats by Chronic Antihypertensive Therapy With Captopril

Abstract

To determine whether the electrocardiogram (ECG) could detect a reduction in ventricular mass with chronic antihypertensive therapy, ECGs were obtained in two year old female normotensive (NR) and spontaneously hypertensive rats (SHR) following nine months of treatment with captopril or water. The ECG of untreated SHR was considerably different than that of age- and sex-matched NR. The notable differences were the increased voltage, left axis deviation, a delay in the intrinsicoid deflection, and the increased frequency of left atrial abnormalities. Chronic captopril therapy produced a substantial reduction in left ventricular mass in the SHR (NR, 0.63±0.01; SHR, 1.08±0.03; captopril SHR, 0.80±0.04g). The ECG reflected this regression of left ventricular hypertrophy since the voltage and axis of the treated SHR were no longer different than those of NR. Thus, the ECG may be effective in evaluating the regression of cardiac hypertrophy in response to chronic therapy in experimental hypertension.