Sinus bradycardia

Sinus bradycardia

Sinus bradycardia can be identified as a rhythm with normal P waves (positive in inferior leads and lead I) occurring at a rate less than 60 per minute. QRS width and morphology are normal, unless there is an associated bundle branch block. Very often in a person with pre-existing cardiac ailment, it is due to drugs like beta blockers, digoxin or non-dihydropyridine calcium channel blockers (verapamil or diltiazem). Sinus bradycardia could also be due to raised intracranial tension, hypothyroidism and sometimes due to a viral infection. It is a usual phenomenon in inferior wall myocardial infarction, especially during reperfusion. In the elderly, the possibility of sick sinus syndrome has to be thought of. Lithium toxicity is seen in an occasional psychiatric patient with sinus bradycardia.

The management of sinus bradycardia is essentially the treatment of the cause, which may involve the withdrawal of a causative drug. In symptomatic cases, atropine or isoprenaline may be needed occasionally. Temporary transvenous pacing may needed in rare cases.