内科学教学课件：心律失常-英文.pptVIP

Cardiac Arrhythmia INTRODUCTIONArrhythmia: abnormalities of cardiac rhythm and conduction Arrhythmias can be lethal (sudden cardiac death ) , symptomatic ( syncope , near syncope dizziness , or palpitations ) , or asymptomatic . They are dangerous to the extent that they reduce cardiac output , so that perfusion of the brain or myocardium is impaired , or tend to deteriorate into more serious arrhythmias with the same consequences Anatomy of cardiac conduction system Category of ArrhythmiaAbnormalities of impulses generatingAbnormalities of impulses conduction Abnormalities of impulses generating Sinus arrhythmias: sinus bradycardia, sinus tachycardia, sinus arrest, Abnormalities of impulses generatingEctopic rhythm:1.Passive abnormalrhythm: escape beat, escape rhythm (atrial, AV junctional, ventricular) 2.Initiative abnormal rhythm: ⑴premature beat(atrial, AV junctional, ventricular)⑵paroxysmal tachycardia(atrial, AV junctional,ventricular)⑶atrial flutter, atrial fibrillation⑷ventricular flutter, ventricular fibrillation Abnormalities of impulses conduction1.physiologic2.pathologic: sinoatrial block, intra-atrial block, atrial ventricular block, bundle branch block, intra-ventricular block.3.abnormal pathway conduction: preexcitation syndrome MECHANISMS OF ARRHYTHMIASMost arrhythmias can be classified as(1) disorders of impulse formation or automaticity (2) abnormalities of impulse conduction(3) reentry (4) triggered activity Altered automaticity is the mechanism for sinus node arrest , many premature beats , and automatic rhythms as well as an initiating factor in reentry arrhythmias . Abnormalities of impulse conduction can occur at the sinus or atrioventricular node , in the intraventricular conduction system , and within the atria or ventricles . These are responsible for sinoatrial exit block at the node or below , and for establishing reentry circuits . Reentry is the underling mechanism for many arrhythmias , incl