Critical Heart Rate Dependent LBBB: Need Caution!

Abstract

Right bundle branch block (RBBB) and left bundle branch block (LBBB) are commonly seen in geriatric cases posted for surgeries. LBBB usually results from conduction system degeneration or myocardial pathology. LBBB is often associated with hypertension, myocarditis, coronary heart disease, aortic valve disease, cardiomyopathy etc. We report a case of diagnosed LBBB preoperatively posted for emergency spinal decompression. After induction of anaesthesia, the heart rate settled below 77 beats per minute (bpm) and led to reversion of LBBB to normal sinus rhythm. LBBB is a red flag diagnosis to the anaesthesiologist. But the knowledge of critical heart rate is important; below which the rhythm may revert back to normal sinus rhythm. The knowledge to differentiate between myocardial ischaemia and LBBB is the need of the hour.