[Early and late hemodynamic changes following operative therapy of hypertrophic obstructive cardiomyopathy]

10 patients (8 men, 2 women; 24 to 72 years of age at the time of operation) with hypertrophic obstructive cardiomyopathy (HOCM) underwent exercise tests a mean of 10 +/- 3.7 months before as well as 12 +/- 1.1 and 52 +/- 6.3 months after subvalvular septal myectomy. The following hemodynamic parameters were assessed: heart rate, arterial pressure, total body oxygen consumption, arterio-venous oxygen difference, stroke volume, cardiac output, and pulmonary artery pressure. Clinical symptoms improved in all patients after surgery, at the first postoperative investigation in 8 patients by one class and in 2 patients by two classes according to the New York Heart Association's classification. At the second postoperative study, 2 patients reported a further improvement, 5 patients no further change, and 3 patients a partial deterioration of symptoms. Exercise tolerance, however, did not decrease in any patient. It increased from a preoperative mean of 68 +/- 7.5 watts to 90 +/- 10.0 watts (p less than 0.02) at the first and 102 +/- 14.1 watts at the second postoperative study. The hemodynamic parameters showed the following alterations at the highest exercise levels (mean 68 +/- 7.5 watts) reached by individual patients in all three exercise studies: heart rate, at the first postoperative study, was an average of 16 bpm, i.e. 13% lower than in the preoperative test, and then remained constant. Arterial blood pressure showed no definite alterations. Total body oxygen consumption was unchanged at the first postoperative evaluation, but increased at the second postoperative test by an average of 132 ml/min, i.e. 10% (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)