The rate dependent bundle branch block -- transition from left bundle branch block to intraoperative normal sinus rhythm.

A chronic hypertensive patient with electrocardiogram (ECG) showing left bundle branch block (LBBB) was given general anesthesia for right modified radical mastectomy. Her ECG reverted to normal sinus rhythm intermittently during peri-operative period. This intermittent rate-dependent LBBB is a rare entity. Though hypertension is one significant co-morbid condition, the risk evalution of LBBB during anesthesia only on an ECG finding, is not justifiable. Rather patient should be investigated further for any cardiac risk.