Regression after Open Valvotomy of Infundibular Stenosis Accompanying Severe Valvular Pulmonic Stenosis

Abstract

Three patients, an infant, a child, and an adult, with severe valvular stenosis were observed to have a right ventricular systolic pressure greater than 100 mm. Hg following valvotomy performed under hypothermia through an opening in the pulmonary artery. The obstruction that remained was localized by pressure measurements to the outflow tract of the ventricle. Intra-cardiac exploration of this region indicated that the obstruction was not rigid but appeared to be due to contraction of the hypertrophied muscle. During six to twelve months postoperatively electrocardiographic signs of right ventricular hypertrophy disappeared, and cardiac catheterization 10 to 15 months after operation disclosed pressures within normal limits in the right ventricle with only slight or no trans-valvular gradients. It appeared that the severe valvular stenosis was responsible for marked hypertrophy of the wall of the right ventricle, sufficient by itself to narrow the outflow tract once the obstruction at the valve was relieved. Restoration of valve function by valvoplasty reduced the work of the ventricle so that the hypertrophied myocardial fibers returned to a more nearly normal size and was accompanied by complete regression of this secondary form of infundibular stenosis. The surgical implication from these observations is that if the value has been opened fully and no fixed obstruction, such as a diaphragm or ring, is found within the right ventricle, then additional attempts to treat the muscular stenosis surgically are unnecessary.