The Infundibular Factor in Relation to Valvotomy

It has been found that after pulmonary valvotomy for pulmonary valvular stenosis with an intact interventricular septum a satisfactory fall in right ventricular pressure is not always achieved immediately. In order to explain this, Kirklin, Connolly, Ellis, Burchell, Edwards, and Wood (1953) concluded that before the development of open heart surgery there were two main reasons: (1) failure to open the valve adequately (they advocated repeated attempts until a satisfactory diminution in the gradient could be demonstrated), and (2) stenosis of the infundibulum due to right ventricular hypertrophy, a hypothesis also suggested by Soulie, Joly, Carlotti, Sicot, and Voci (1952). Introducing the open transarterial operation under hypothermia, Swan and his associates (Swan, Cleveland, Mueller, and Blount, 1954) and Blount, McCord, Mueller, and Swan (1954) obtained a fall in right ventricular pressure to normal and an abolition of the gradient across the pulmonary valve in almost all their cases, assessing them after some months. In a recent review of their later cases (Blount, van Elk, Balchum, and Swan, 1957), they have found that in one-third, approximately, there is a residual gradient three months after operation; they explained this as an infundibular stenosis, which could be obscured by the distal, i.e., valvular, stenosis before operation. Brock (1957) was of the same opinion. Some fixed, or fibrous, narrowing of the infundibulum in the tetralogy of Fallot was demonstrated in all but one of 25 cases examined by Bing, Weber, Sparks, Balboni, Vitale, and Hanlon (1954), using casts of the ventricular lumen made at necropsy. But they failed to show any narrowing of the right ventricular outflow tract in cases of pulmonary valvular stenosis with a closed septum. An additional muscular element to the infundibular stenosis of the tetralogy of Fallot has been demonstrated by Rodbard and Shaffer (1956), who showed the