A new therapeutic concept of enlarging the outflow tracts of both ventricles with a patch and inserting an aortic prosthesis has been developed for the treatment of tunnel subaortic stenosis. This operation has been applied clinically since June 1974 on several types of obstruction in the outflow tract of the left ventricle.
Twenty-one operations have been performed on 20 patients under the age of 18 years, with an overall mortality of 24% and no late deaths. Seven patients developed complete right bundle branch block or left anterior hemiblock or both as a result of this operation; transient atrioventricular block and complete left bundle branch block occurred in one patient each. In no case, however, did rhythm disturbances contribute to death. In one patient, the septal incision injured a septal coronary artery, with fatal result.
Fourteen patients had catheterization studies postoperatively. Although previous conventional surgery had been unsuccessful, aortoventriculoplasty (AoVPI) reduced the mean gradient across the left ventricular outflow tract significantly (p <0.01), from 94.7 ± 25.5 mm Hg to 14.4 ± 17.2 mm Hg, leaving the end-diastolic pressure practically unchanged. No significant defect remained in the patch-covered septal incision.
Thus, we consider AoVPI to be the operation of choice for tunnel subaortic stenosis, for valvular aortic stenosis with a narrow annulus and in cases where an artificial aortic valve has become too small because of the patient's growth.