Bradycardia

Bradycardia is a slow heart rate; a pulse rate of less than 60 beats per minute in an adult. It may be divided up into groups much the same as tachycardia, but is more likely to be a sinus rhythm.

Possible situations include:

• sinus bradycardia - where the abnormally slow pulse is the result of pacemaking from the sino-atrial node. This occurs in situations such as increased intracranial pressure, jaundice, sino-atrial disease, hypothyroidism and in trained athletes
• atrioventricular dissociation - this occurs in situations such as heart block and rarely, hypothermia.

Occasional ectopics are seen in ventricular bigemini.

Click here for example ECGs in cases of clinical bradycardia - with explanations of significance of ECG findings

Reference:

1. Spodick DH. Normal sinus heart rate: sinus tachycardia and sinus bradycardia redefined. Am Heart J. 1992 Oct;124(4):1119-21.