2. Heart rhythm 1)Sinus arrhythmia 2)Premature beat a sudden extrasystole of the heart in the basic of normal heart rhythm S1个;S2 Pulse absent Ectopic point at atrial, Av node, ventricle2. Heart rhythm • 1) Sinus arrhythmia • 2) Premature beat: A sudden extrasystole of the heart in the basic of normal heart rhythm S1; S2 Pulse absent Ectopic point at atrial, AV node, ventricle