The Electrocardiogram in Muscular Subaortic Stenosis

FOLLOWING Brock's' recognition that hypertrophied muscle in the left ventricular outflow tract could obstruct left ventricular outflow, much interest has centered on the nature of this hypertrophy. Initial reports suggested that concentric hypertrophy of the left ventricle was the underlying cause of the obstruction of the outflow tract. -3 Following Teare's4 description of asymmetrical hypertrophy of the heart (hypertrophy centered in the ventricular septum often extending into the anterior wall of the left ventricle), considerable evidence has been accumulated to indicate that asymmetrical, rather than concentric hypertrophy of the left ventricle, is the more common cause for muscular subaortic stenosis.' 13 More recently, a number of observers have noted abnormal Q waves in the electrocardiograms in some cases of muscular subaortic stenosis,4 6-9, 11, 13-22 and some have suggested that these Q waves may indicate ventricular septal hypertrophy.13 14, 17-23 Tall R waves in the right precordial leads have also been recorded in cases of muscular subaortic stenosis in which there was no cause for, or evidence of, significant right ventricular hypertrophy.4 13 15-17, 19, 23 In a previous communication, we suggested that both the Q waves in the left precordial and limb leads and the tall R