[Enzyme activity of creatine kinase and its MB isoenzyme in endocardial countershock]

Enzymatic activity of total serum CPK and of MB iso-enzyme was studied to assess changes in the myocardium caused by cardioversion. Assay of enzymes was performed prior to cardioversion and every two hours during the first 24 hours after it was administered. 79 instances of cardioversion were reported in a series of 56 patients, including 14 females (mean age 45 years). Cardioversion was employed in the treatment of 23 patients with supra-ventricular tachycardia, and in 56 cases to treat chronic ventricular tachycardia including 23 of ventricular tachycardia arising as a complication of myocardial infarction, 17 cases of arrhythmia-inducing disorders of the right ventricle, 8 cases of primary cardiomyopathy, 7 of idiopathic ventricular tachycardia and 1 of a congenital disorder. The energy of the electric shock administered was 620 +/- 522 joules during the 3 shocks per session, on the average, delivered by an Odam capacitor discharge using a distal electrode connected to the positive pole of an endocardial electrode catheter. A maximum level of total serum CPK equal to 333 +/- 396 U/l was observed 6 +/- 3 hours after cardioversion. The highest level of isoenzymes MB recorded was 30 +/- 24 U/l 4 +/- 2 hours after cardioversion. Compared to electric shock administered to treat ventricular tachycardia, an electric current applied to the His bundle produced the least MB isoenzyme activity (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)