Spontaneous remission of left bundle branch block during anaesthesia

Routine pre-operative evaluation of a 58-year-old man scheduled for repair of an inguinal hernia, disclosed a blood pressure of 200/100 mmHg. This decreased to 150/100 mmHg after a period of rest. An electrocardiogram taken as a result of this chance finding showed left bundle branch block. There were no other cardiovascular symptoms or signs. Soon after induction of general anaesthesia, the conduction defect disappeared. The return to sinus rhythm was sudden and sustained and was not related to changes in heart rate or blood pressure. One month later, his electrocardiograph remained normal.