Late results after resection of discrete and tunnel subaortic stenosis

From May 1969 to June 1988, 84 consecutive patients ranging in age from 6 months to 61 years (mean 18 years) underwent surgery for fixed subaortic stenosis (SAS). A discrete fibrous or fibromuscular structure was present in 81 patients, while 3 presented with a tunnel type of obstruction. SAS was treated by sharp resection of the tissue and routine myotomy or myectomy of the hypertrophied left ventricular (LV) muscle (57 patients, group 1), while more recently, the lesion was treated by simple fibrous tissue enucleation (27 cases, group 2). There were 3 hospital deaths (3.6%) and 3 late deaths (overall mortality 7.1%). Eight patients required late reoperation because of recurrent SAS [3], aortic valve stenosis [2], aortic incompetence (AI) [2] and persistent mitral incompetence [1]. Seventy of 78 late survivors were reevaluated 3 months to 110 months after surgery (mean 75 +/- 48 months) by means of a complete cardiac catheterization or by 2-D echo and Doppler. The transaortic peak pressure gradient decreased from 97 +/- 43 (range 20-205 mmHg) to 11 +/- 16 mmHg (range 0-60 mmHg) in group 1 and from 72 +/- 38 mmHg (range 18-160 mmHg) to 3 +/- 7 mmHg (range 0-25 mmHg) in group 2 (P = NS). In 55 patients who have not undergone surgery on the aortic valve, AI remained unchanged in 31, decreased from mild to nil in 21 and from moderate to mild in 3. We conclude that simple blunt enucleation of SAS is an effective procedure in relieving LV outflow obstruction even if a myotomy or myectomy of the underlying hypertrophied muscle is not routinely used.(ABSTRACT TRUNCATED AT 250 WORDS)