[Severe disorders of auriculoventricular conduction after aortic valve replacement. A postoperative electrophysiological study in 36 patients and the long-term follow-up].

Cardiac conduction defects (CD) are common in patients with aortic valve diseases. Several studies have suggested that the occurrence of complete heart block at the time of valve replacement is related with preoperative conduction defects and with other factors like calcium deposits, aortic gradient or poor left ventricular function. We evaluated 36 patients undergoing isolated aortic valve replacement in 29 of them, combined mitroaortic in four, isolated mitral valve replacement in two and subvalvular myectomy in one. In all of them an electrophysiologic study was done at the postoperative period. In group 2 (with preoperative CD) patients were older (mean age +/- SEM; 56.57 +/- 8.90) than in group 1 (without CD) (45.64 +/- 14.79) (p less than 0.02). Surgical times were higher in group 1 than in group 2 (p less than 0.01 and p less than 0.005). The site of block was distal to the His bundle in 59% of patients in group 1 and in 47% in group 2 (p-NS). Complete AV block occurred in 70.5% of patients in group 1 while was of 36.8% in group 2 (p less than 0.05). Severity of conduction defects was unrelated with the type of valve disease, aortic valve calcification or gradient or with poor left ventricular function. Preoperative conduction defects were not responsible of more severe postoperative conduction defects. On late follow-up permanent pacemakers were unnecessary in 33% of patients in group 1 and in 75% in group 2 (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)