Mobilization of the left and right fibrous trigones for relief of severe left ventricular outflow obstruction

Background: There is still no agreement about the optimal method of surgica l relief of fixed subaortic stenosis, particularly the severe forms. Object ives: The purpose of this study was to describe a new technique for the rel ief of subaortic stenosis based on analysis of the functional anatomy of th e left ventricular outflow tract and pathophysiologic features of subaortic stenosis, Methods and patients: We propose that one of the basic abnormali ties in subaortic stenosis is interference with the hinge mechanism provide d by the 2 fibrous trigones with progressive deposition of fibrous tissue i n these angles. The technique described in this paper consists of excision of all components of the fibrous "ring," with mobilization of the left and right fibrous trigones, This results in the restoration of the normal dynam ic behavior of the left ventricular outflow tract with maximal widening of the outflow tract as the result of backward displacement of the subaortic c urtain and anterior leaflet of the mitral valve, This technique has been us ed in 57 consecutive patients who ranged in age between 5 months and 56 yea rs (mean, 15.5 +/- 10.6 years). Gradients across the left ventricular outfl ow tract were between 45 and 200 mm Hg (mean, 86.7 mm Hg), Additional lesio ns were present in 10 patients, and 7 patients had had 8 previous operation s on the left ventricular outflow tract. At operation, in addition to resec tion of subaortic stenosis, 3 patients had aortic valvotomy, 2 patients had homograft replacement of the aortic valve, 7 patients had patch closure of a ventricular septal defect, and 1 patient had open mitral valvotomy. Resu lts: There were 2 early deaths and I late sudden death during the follow-up period that ranged from 1 month to 25 years (mean, 15.2 years). One patien t experienced the development of endocarditis on the aortic valve 7 years a fter operation, which was successfully treated by homograft replacement. Po stoperative gradients across the left ventricular outflow tract varied from no gradient to 30 mm Hg (mean, 8 mm Hg). There were no instances of recurr ence of a gradient across the left ventricular outflow tract. Conclusion: I t is concluded that mobilization of the left and right fibrous trigones res ults in durable relief of subaortic stenosis.