Hypertrophic Infundibular Stenosis Complicating Simple Pulmonary Valve Stenosis

Abstract

Pulmonary valvotomy by the closed transventricular technique was introduced as an alternative to the Blalock-Taussig operation in Fallot's tetralogy (Brock, 1948) and for relief of pulmonary stenosis in the presence of a closed ventricular septum (Brock and Campbell, 1950). In Fallot's tetralogy, at least until closure of the ventricular septal defect became feasible, some residual pulmonary stenosis was considered desirable. With a normal aortic root, however, complete relief of the stenosis was sought. It was soon found that this could not always be achieved at operation and for this three main reasons have been suggested. Kirklin et al. (1953), reporting twelve cases of transventricular pulmonary valvotomy, discussed the possibility that right ventricular hypertrophy might result in secondary stenosis in the infundibular region. Brock (1955), in an account of control mechanisms in the outflow tract of the right ventricle following a careful study extending over seven years, described and illustrated with pressure records secondary infundibular stenosis after pulmonary valvotomy. He discussed two factors responsible for this, the first mechanical, particularly in the region of the greatly enlarged crista supraventricularis, the second an exaggeration of the infundibular muscle tonus that normally functions to support the pulmonary valve ring. He suggested that, when this condition prevented complete relief of right ventricular hypertension, even a partial relief might suffice to allow regression of right ventricular hypertrophy and thus of secondary infundibular obstruction.Comparing their results of transventricular pulmonary valvotomy and ofthe open procedure Swan et al. (1954) expressed the view that inadequate valvotomy was the usual cause of failure to reduce right ventricular pressure with the closed technique. They contrasted the complete relief obtained in every one of five open operations in which they performed pulmonary valvotomy through the pulmonary artery, using hypothermia, and concluded that hypertrophy of the right ventricle was not a cause of outflow obstruction. The same group, however, found later that open valvotomy did not always completely remove the systolic gradient between right ventricle and pulmonary artery (Blount et al., 1957) and agreed that this was sometimes due to infundibular obstruction which, they observed, was capable of regression. Campbell and Brock (1955) suggested a third explanation of residual stenosis, namely that the valve ring itself and the outflow tract were small. They noted that, in spite of a high residual gradient following valvotomy, the clinical improvement and the diminution of right ventricular strain were better than they had expected. In one such case the right ventricular pressure was found to have fallen further at recatheterization a year after operation. McGoon and Kirklin (1958)

Pulmonary valve stenosis without ventricular septal defect: results of surgery.

“…Inadequate enlargement of the valve orifice was usually blamed for poor results when closed valvotomy was the only practicable procedure (Swan, Cleveland, Mueller, and Blount, 1954 (Dilley et al, 1963), and that complete relief of the stenosis did not necessarily cause an immediate drop in gradient. Hypertrophic infundibular stenosis was recognized by Connolly, Lev, Kirklin, andWood in 1953 andindependently by Brock in 1955. Removal of the valvar obstruction allows the hypertrophied walls of the outflow tract to meet in systole and to cause an obstruction that may be little less severe than the previous one at valve level (Johnson, 1959). There is then no immediate relief of the right ventricular hypertension (McGoon andKirklin, 1958: Gerbode et al, 1960).…”

“…Hg and reported an incidence of 77 %. Johnson (1959) called it 'an infundibular gradient after valvotomy of 20 mm. Hg or more' and found that it followed 51 ,, of closed and 77% of open valvotomies.…”

“…Johnson (1959) reported that 20% of patients with right ventricular systolic pressures above 100 mm. Hg after valvotomy died within 24 hours and 60'x,'/ had evidence of cardiac failure.…”

“…Long-term effects It is usually stated that the hypertrophied infundibulum eventually involutes if patients survive the immediate post-operative period (Engle, Holswade, Goldberg, Lukas, and Glenn, 1958), but Campbell (1959) showed that complete regression of the electrocardiogram was unlikely over the age of 20, if infundibular hypertrophy was severe, and and Johnson (1959) reported persistently raised right ventricular pressures even years after complete valvotomies. Brock (1961) found that the incidence of incomplete resolution was 22% in patients left Hg.…”

Reversed Interatrial Shunt Following Complete Relief of Pulmonary Valve Stenosis

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Persistence of a right-to-left interatrial shunt after relief of pulmonary valve stenosis is not necessarily related to the effectiveness of relief of the obstruction, but may reflect continued right ventricular dysfunction.When operative relief of pulmonary stenosis is too long delayed the results may be disappointing (Johnson, 1959;Campbell, 1959;Brock, 1961;McIntosh and Cohen, 1963). The present communication concerns six patients who were cyanosed following pulmonary valvotomy despite a normal right ventricular pressure both at rest and on exercise, and who were among a series of 56 patients with pulmonary valve stenosis operated upon under cardio-pulmonary bypass at Hammersmith and Brompton Hospitals between 1958 and 1963.

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