Ectopic Beats

This presentation is about ectopic beats and their treatment.

1. بسم الله الرحمن الرحیم

2. E ctopic Beats

3. Ectopic Beats (Extra systoles; Premature Beats ) Definition-A heart beat occurring as a result of an impulse originating in an area other than the sinoatrial (SA) node is known as an ectopic beat. Ectopic beats are classified based on the origin of the impulse (ectopic focus). Supraventricular Atrial (arising from atrium) Junctional (arising from AV junction) Ventricular Hemodynamics-An ectopic impulse occurs in diastole. The normal sinus impulse (arising from SA node) following an ectopic impulse will find the ventricles refractory, and hence, not conducted into the ventricles, resulting in a "missed " or "dropped" beat. This is responsible for the "compensatory pause". Compensatory pause allows more filling of the ventricles, and hence, the subsequent beat is more forceful. Symptoms include extra beats, thumping beats or missed beats. Signs include irregularity in rhythm, missing of beats, post-ectopic bounding beat and cannon waves on J VP.

4. Supraventricular Ectopics (Atrial Ectopics ; Atrial Premature Beats ) Causes Idiopathic in healthy people Anxiety Excessive coffee, tea or tobacco Ischemic heart disease Valvular heart diseases

5. Electrocardiogram (ECG) The ECG shows an abnormal P wave (P' wave) that occurs early in the cardiac cycle. Sometimes, it may get buried in the preceding T wave. It may be inverted if the source of its origin is near the AV node. R-R interval preceding and following the ectopic beat is less than twice the basal R-R interval, i.e. the pause following the ectopic is not fully compensated. Most often, the QRS complex is narrow and identical to the sinus rhythm. However, occasionally, P' is conducted aberrantly that results in a wide QRS complex. This must be distinguished from ventricular ectopic beat. Treatment Treatment is that of the underlying cause Supraventricular ectopics can sometimes precipitate atrial tachycardia, flutter and fibrillation.

6. Ventricular Ectopics (Ventricular Extrasystoles ; Ventricular Premature Beats) Causes • Idiopathic in healthy people • Excessive tea, coffee and alcohol • Acute myocardial infarction • Myocardial ischaemia • Myocarditis • Digitalis toxicity • Hypokalemia • Mitral valve prolapse

7. Electrocardiogram(ECG) A P V C is characterized on the ECG by a wide, bizarre QRS complex, more than 0.12 seconds in duration and usually without a preceding P wave . Due to abnormal re- polarisation , PVC is associated with secondary T wave changes that include widening of T wave and deflection of T wave opposite to that of ectopic QRS complex. The pause is fully compensated so that the sum of R-R intervals preceding and following the ectopic QRS equals double the normal sinus R-R interval .

8. When a PVC depolarizes the ventricles at a similar time as a conducted atrial beat, a fusion beat is seen. Ventricular bigerniny is present when a ventricular premature beat follows each sinus beat. Ventricular trigerniny is present when two sinus beats are followed by the ventricular premature beat. Thus, every third beat is a ventricular premature beat.

9. Treatment Treat the underlying cause In the absence of ischemia, PVCs alone rarely require any specific pharmacologic therapy. In ischemic heart disease lignocaine may be required if the PVCs are multiform, couplets (two consecutive PVCs) are present, or R-on-T phenomenon (occurrence of PVC on the preceding T wave) is present. Symptomatic healthy people can be treated with Beta-blockers , amiodarone , disopyramide or mexiletine