Heart rhythm disorders (Arrhythmia)
Disorders of heart rhythm are technically known as cardiac arrhythmia. Rhythm disorders can be irregularity in the rhythm or change in the heart rate (increase or decrease). Commonest irregularity in the heart rhythm is due to abnormal beats originating from the lower chambers known as ventricular ectopic beats (VPB or VPC – ventricular premature complexes). Increase in heart rate can be due to physiological causes like exercise or due to simple disease states like fever. A decrease in heart rate can occur during deep sleep and when the body temperature falls below normal (hypothermia). There are several disease states which can reduce heart rate like a decrease in the function of the thyroid gland (hypothyroidism) and complete heart block. In complete heart block, the signals generate by the natural pacemaker of the heart, namely sinoatrial node, does not get conducted down to the lower chambers of the heart. The study of heart rhythm disorders is known as cardiac electrophysiology.