cardiovascular disorders
Ectopic Supraventricular Arrhythmias
Atrial premature beats
) or may be a sign of a cardiopulmonary disorder. They are common in patients with Chronic Obstructive Pulmonary Disease (COPD) (COPD). They occasionally cause palpitations. Diagnosis is by electrocardiography (ECG—see figure Atrial premature beat (APB) ). In lead II, after the 2nd beat of sinus origin, the T wave is deformed by an APB. Because the APB occurs relatively early during the sinus cycle, the sinus node pacemaker is reset, and a pause—less than fully compensatory—precedes the next sinus beat. APBs may be normally, aberrantly, or not conducted and are usually followed by a noncompensatory pause. Aberrantly conducted APBs (usually with right bundle branch block morphology) must be distinguished from premature beats of ventricular origin. Atrial escape beatsare ectopic atrial beats that emerge after long sinus pauses or sinus arrest. They may be single or multiple; escape beats from a single focus may produce a continuous rhythm (called ectopic atrial rhythm). Heart rate is typically slower, P wave morphology is typically different, and PR interval is slightly shorter than in sinus rhythm. 