HEMODYNAMIC-FINDINGS IN PATIENTS WITH LEFT-BUNDLE-BRANCH BLOCK AFTER MYECTOMY IN HYPERTROPHIC OBSTRUCTIVE CARDIOMYOPATHY (HOCM)

To determine the hemodynamic effects of postoperative left bundle bran ch block (LBBB) in patients with hypertrophic obstructive cardiomyopat hy (HOCM), we investigated 28 patients using Swan-Ganz pulmonary arter y catheterization at rest and on exercise. Fourteen patients had posto perative LBBB (group A) and 14 had undisturbed intraventricular conduc tion (group B). All patients were examined by clinical investigation, electrocardiogram and bicycle ergometer exercise preoperatively and po stoperatively (mean 6 months). Pulmonary artery pressure and pulmonary capillary wedge pressure were continuously measured, stroke volume in dex and cardiac index were obtained by the thermodilution method. All patients showed an improvement of their clinical symptoms (NYHA class: 2.8 +/- 0.45 before and 1.7 +/- 0.22 after operation) (P < 0.05). The postoperative exercise capacity (Watt) increased significantly (P < 0 .05) in group A by 38 % and in group B by 30 %. The maximum mean pulmo nary artery pressure on physical exercise decreased in group A from 40 .7 +/- 9.1 to 32.5 +/- 8.7 mmHg and in group B from 42.8 +/- 12.4 to 3 2.4 +/- 9.2 mmHg (P < 0.05). The maximal stroke volume index and cardi ac index improved significantly in 9 of 14 patients in each group. Thu s, patients with HOCM and LBBB after myectomy have a marked improvemen t in postoperative hemodynamics, the results equaling those of patient s with undisturbed intraventricular conduction.