13.01.1 Introduction to Cardiac Arrhythmia

Sinus rhythm is normal heart rate. Cardiac arrhythmias are abnormal rhythms of the heart. Tachycardia is faster than normal atrial or ventricular rates, giving atrial tachycardia or ventricular tachycardia. Flutter is fast, irregular beats of the atria or ventricles, giving atrial flutter or ventricular flutter. Often the arrhythmias are progressive, tachycardia turns into flutter, and flutter turns into fibrillation. Fibrillation is fast, irregular quivers of muscle, without a beat. In atrial fibrillation, survival is possible provided the ventricles are still beating normally. Atrial fibrillation can precipitate ventricular fibrillation. Ventricular fibrillation can be deadly, as it is not possible to survive without a heart best. Torsades de pointes are drug-induced ventricular tachycardia. Infarcted or ischemic areas of myocardium can precipitate arrhythmias.

Cardiac arrhythmias are common. Atrial fibrillation affects 0.4% of the general population, but the incidence increases with age to 2-5% of persons over 60 years of age and 10% of those older than 70 years. Ten percent of the survivors of myocardial infarction (MI, heart attack) die during the subsequent year, mostly of cardiac arrhythmias. Fifty percent of patients with heart failure undergo a sudden death, which may be due to cardiac arrhythmia.