Obstructive Phenomena in Ventricular Hypertrophy.

The association of muscle hypertophy in the outflow tract of a ventricle with obstruction to blood flow during systole is being recognized with increasing frequency. This functional stenosis has long been known to appear in the hypertrophied right ventricle following surgical relief of pulmonary valve stenosis (Kirklin et al., 1953; Brock, 1955). It was recognized in the left ventricle by Brock (1957) in patients following aortic valvotomy, and in one during the course of systemic hypertension. In two of the first three patients studied by Morrow and Braunwald (1959), however, there was no apparent cause for the underlying ventricular hypertrophy, resembling in this way that described at autopsy by Teare (1958) as asymmetrical ventricular hypertrophy. Most of the cases described since have been of this type, presenting clinical features of obstruction to left ventricular ejection. In some, associated obstruction has been found in the right ventricle, either in the outflow tract (Morrow and Braunwald, 1959) or lower down in the ventricular cavity (Goodwin et al., 1960). We have encountered this functional lesion in eight patients over the past two years, associated in all with ventricular hypertrophy of unknown cause. The four cases presented here include one whose signs were purely of right ventricular obstruction, with the lesion wholly localized to that chamber.