Intraoperative identification of the conduction system in repair of endocardial cushion defect

Electrophysiological identification intraoperatively of the His-Purkinje system eliminates the complication of complete heart block consequent upon repair of endocardial cushion defect (ECD). Ten patients, 6 with complete ECD and 4 with incomplete ECD, underwent repair of the defect. None of the patients developed heart block. Slight variations were noted in the location of the His bundle in 9 patients, and a major deviation was found in 1 patient with incomplete ECD. The data support the use of intraoperative recordings as a necessary acconpaniment to the operative repair of ECD.