The Electrocardiogram in Muscular Subaortic Stenosis

The electrocardiograms of four patients with muscular subaortic stenosis, in whom there was angiographic evidence of ventricular septal hypertrophy (confirmed at surgery in three), revealed pathological Q waves in the limb leads (except aVR) and the left precordial leads, as well as tall R waves in the right precordial leads. Three patients underwent surgical correction of the stenosis. The left anterior septal ventriculomyotomy abolished the Q waves and diminished the right precordial R waves while at the same time producing left axis deviation believed to be due to severing of the anterior division(s) of the left bundle branch. In the fourth patient the left precordial and limb lead Q waves and right precordial R waves increased following spontaneous development of complete right bundle-branch block. These observations support the belief that the Q-wave and R-wave abnormalities in the electrocardiogram in patients with muscular subaortic stenosis are the result of septal depolarization commencing at the left septal surface and may be related to the overall hypertrophy of the septum, the bizarre myocardial fiber hypertrophy or premature activation of the base of the septum, or all three.