Pulmonary stenosis with intact ventricular septum and Fallot's tetralogy: Assessment of postoperative results by auscultation and phonocardiography

Abstract

A study has been made to determine the value of auscultation and phonocardiography in assessing the result of surgery in cases of pulmonary stenosis with intact ventricular septum and Fallot's tetralogy. In cases of pulmonary or infundibular stenosis with an intact ventricular septum, a successful valvotomy or infundibular resection resulted in marked shortening and softening of the murmur and reduction in the width of splitting of the second sound. Less adequate relief of stenosis caused less shortening of the murmur and less reduction in the splitting. Criteria are given for grading the postoperative severity of the stenosis. In cases of Fallot's tetralogy, a successful valvotomy or infundibular resection (Brock operation) resulted in marked lengthening and intensification of the murmur and, frequently, the emergence of a very soft, audible pulmonary second sound widely separated (average 0.09 second) from the aortic second sound. These changes reflected increased volume rate of pulmonary flow through the stenosis and a rise in pulmonary arterial pressure. Less adequate relief of stenosis caused less prolongation of the murmur and no emergence of a pulmonary second sound. Criteria are given for grading the postoperative result. Auscultation was shown to be an excellent bedside method of predicting the surgical result of a valvotomy in the two conditions, since the change in the length of the murmur and the width of splitting developed rapidly, and accurately reflected the degree to which the stenosis had been relieved. The opposite behavior of the murmur was due to the different dynamic situation in the two conditions. The observations proved that the length of the murmur was directly related to the severity of the stenosis when the ventricular septum was intact, but inversely related in cases of the tetralogy. Following complete valvotomy under direct vision, the right ventricular pressure may fail to drop adequately because of severe subvalvular muscular hypertrophy. The resultant secondary infundibular stenosis may or may not regress over a period of time. The value of serial sound tracings in detecting the trend is emphasized. Gradual shortening of the initially prolonged murmur and narrowing of the split second sound indicate gradual reduction of right ventricular pressure and stenosis. A successful Blalock-Taussig operation for the tetralogy did not lengthen the pulmonary systolic murmur, since the stenosis was not relieved by this operation. This indirectly confirmed the view that the length of the murmur is a function of the degree of stenosis, provided that the systemic resistance remains constant. However, auscultation was of value in other respects. The development of a loud continuous murmur, especially if associated with the emergence of a recordable pulmonary second sound, ensured a good result from this operation. The use of auscultation in evaluating the result of the operation for complete repair of the septal defect and relief of the stenosis in cases of the tetralogy is discussed. The ideal end result is either a short ejection systolic murmur and narrow splitting of the second sound or no murmur at all, with normal heart sounds. The use of amyl-nitrite inhalation and phenylephrine in determining the origin of a residual systolic murmur is discussed.