心律失常总论课件.ppt

1、心律失常总论心律失常总论Outline Arrhythmia is any of a group of conditions in which the electrical activity of the heart is irregular or is faster or slower than normal.The heartbeat may be too fast(over 100 beats per minute)or too slow(less than 60 beats per minute),and may be regular or irregular.A heart beat

2、 that is too fast is called tachycardia and a heart beat that is too slow is called bradycardia.Although many arrhythmias are not life-threatening,some can cause cardiac arrest.2DefinitionThe Origin,Rate,Rhythm,Conduct velocity and sequence of heart activation are abnormally3Arrythmia related Cardio

3、anatomyThe cardiac muscle majority is composed of the ordinary cardiac muscle textile fiber,the small part for the cardiac muscle textile fiber of special differentiation,latter composes the cardiac pacing-conduction system4Cardiac Conduction SystemSAN Internodal pathways AVN His bundle L./R.bundle

4、branch Purkinje fibers5Pacing conduction system6Pathogenesis and Inducement of Arrhythmia Some physical conditionPathological heart diseaseOther system disease Electrolyte disturbance and acid-base imbalancePhysical and chemical factors or toxicosis7Mechanism of Arrhythmia Abnormal heart pulse forma

5、tionqSinus pulseqEctopic pulseqTriggered activity Abnormal heart pulse conductionqReentryqConduct block8 Phase 1 快速复极初期：钾离子外流 Phase 0 快速或上升钠离子内流入进入细胞进行除极 Phase 2 平台期:持续的钠离子内流和缓慢钙离子内流和钾离子外流 Phase 3 快速复极末期:钾离子外流 Phase 4 静息期5 Phases心肌细胞的动作电位Abnormal heart pulse formationAutomaticityTriggered activity触发

6、机制后电位产生于动作电位的第3相（早期）或第4相（晚期）可触发心律失常10Automaticity Heart cells other than those of the SA node depolarize faster than SA node cells,and take control as the cardiac pacemaker.Factors that enhance automaticity include:q SANS,PANS,CO2,O2,H+,stretch,hypokalemia and hypocalcaemia.Examples:Ectopic atrial t

7、achycardia or multifocal tachycardia in patients with chronic lung disease OR ventricular ectopy after MI11Triggered activity is like a domino effect where the arrhythmia is due to the preceding beat.Delayed after-depolarizations arise during the resting phase of the last beat and may be the cause o

8、f digitalis-induced arrhythmias.Early after-depolarizations arise during the plateau phase or the repolarization phase of the last beat and may be the cause of torsades de pointes(ex.Quinidine induced)12Abnormal heart pulse conduction:Reentry:most common13Fast Conduction PathSlow RecoverySlow Conduc

9、tion PathFast RecoveryReentry RequiresElectrical ImpulseCardiac Conduction Tissue1.2 distinct pathways that come together at beginning and end to form a loop.2.A unidirectional block in one of those pathways.3.Slow conduction in the unblocked pathway.2022-11-13四川大学华西医院14Fast Conduction PathSlow Reco

10、verySlow Conduction PathFast RecoveryThe“Re-Entry”Mechanism of Ectopic Beats&RhythmsElectrical ImpulseCardiac Conduction TissueTissues with these type of circuits may exist:in microscopic size in the SA node,AV node,or any type of heart tissue in a“macroscopic”structure such as an accessory pathway

11、in WPW2022-11-13四川大学华西医院15Fast Conduction PathSlow RecoverySlow Conduction PathFast RecoveryPremature Beat ImpulseCardiac Conduction Tissue1.An arrhythmia is triggered by a premature beat 2.The beat cannot gain entry into the fast conducting pathway because of its long refractory period and therefor

12、e travels down the slow conducting pathway only Repolarizing Tissue(long refractory period)The“Re-Entry”Mechanism of Ectopic Beats&Rhythms2022-11-13四川大学华西医院163.The wave of excitation from the premature beat arrives at the distal end of the fast conducting pathway,which has now recovered and therefor

13、e travels retrogradely(backwards)up the fast pathway Fast Conduction PathSlow RecoverySlow Conduction PathFast RecoveryCardiac Conduction TissueThe“Re-Entry”Mechanism of Ectopic Beats&Rhythms2022-11-13四川大学华西医院174.On arriving at the top of the fast pathway it finds the slow pathway has recovered and

14、therefore the wave of excitation re-enters the pathway and continues in a circular movement.This creates the re-entry circuitFast Conduction PathSlow RecoverySlow Conduction PathFast RecoveryCardiac Conduction TissueThe“Re-Entry”Mechanism of Ectopic Beats&Rhythms2022-11-13四川大学华西医院18Atrial Re-entry a

15、trial tachycardia atrial fibrillation atrial flutterAtrio-Ventricular Re-entry Wolf Parkinson White supraventricular tachycardiaVentricular Re-entry ventricular tachycardiaAtrio-Ventricular Nodal Re-entry supraventricular tachycardiaRe-entry Circuits as Ectopic Foci and Arrhythmia Generators2022-11-

16、13四川大学华西医院19bRADYCARDIASA slow rhythm(less than 60 beats/min)May be caused by a slowed signal from the SAN,a pause in the normal activity of the SAN,or by blocking of the electrical impulse on its way from the atria to the ventricles(AV block or heart block)May also be present in the normally functi

17、oning heart of endurance athletes or other well-conditioned persons2022-11-13四川大学华西医院20MECHANISM OF BRADYCARDIAS 窦房结自律性受损如因炎症、缺血、坏死或纤维化可致窦房结功能衰竭，起搏功能障碍，引起窦性心动过缓，窦性停搏 传导阻滞qSAN及A病变，可引起S-A阻滞等qAVB是由于AVN或房室束的传导功能降低，SAN的兴奋激动不能如期向下传导而引起，可分为生理性和病理性两种 病理性常见于风湿性心肌炎、白喉及其他感染、冠心病、洋地黄中毒等 生理性多系迷走神经兴奋性过高21Classific

18、ation of Arrhythmia Atrial Junctional arrhythmia Ventricular Heart blocks Sudden arrhythmic death syndromeArrhythmia may be classified by rate(normal sinus rhythm,tachycardia,bradycardia)or mechanism(automaticity,reentry,junctional,fibrillation).It is also appropriate to classify by site of origin:2

19、2Diagnosis of ArrhythmiaMedical HistoryPhysical ExaminationLaboratory Test23242526ELECTROCARDIOGRAM“5”steps approach to arrhythmiasqStep1:Is there a“QRS”qStep2:Is there a“P”Waveq Step3:What is the relationship between the P waves and the QRS complexes?qStep4:Calculate rateqStep5:Miscellaneous27Step

20、1:Is there a“QRS”(No pulse)YESNOCHAOTIC FLAT LINEWIDENARROWPEAVFAsystoleVT28Step 2:Is there a“P”WaveYESNOVARYCONSTANTMORPHOLOGYRATE220 to 350AFJUNCTIONALInvertedRR IntervalJUNCTIONALAtrial Flutter293031Step 3:What is the relationship between the P waves and the QRS complexes?32 0.2Io AVBConstant?Yes

21、IIo AVB type 2NoRR intervalYesIIIoAVBNoType1 IIoPR intervalPR intervalHEART BLOCKn“P”=n“QRS”?NoYesConstant?331st Degree block(AV Nodal Delay)343536Event Monitors Holter monitoring:Document symptomatic and asymptomatic arrhythmias over 24-48 hours.Can also evaluate treatment effectiveness in a-fib,pa

22、cemaker effectiveness and identify silent MIs.Trans-telephonic event recording:patient either wears monitor for several days or attaches it during symptomatic events and an ECG is recorded and transmitted for evaluation via telephone.Only 20%are positive,but still helpful.37Exercise testing Symptoms

23、 only appear or worsen with exercise.Also used to evaluate medication effectiveness(esp.flecanide&propafenone)You can assess SA node function with exercise testing.Mobitz 1(Wenkebach)is blockage at the AV node,so catecholamines from exercise actually help!Mobitz 2 is blockage at bundle of His,so it

24、worsens as catecholamines from exercise increase AV node conduction,thus prognosis is worse.q*PVCs occur in 10%without and 60%of patients with CAD.*PVCs DO NOT predict severity of CAD(neither for nor against)!38Signal Averaged ECG Used only in people post MI to evaluate risk for v-fib or v-tach.Dama

25、ge around the infarct is variable,so this measures late potentials(low-signal,delayed action potentials)as they pass through damaged areas.Positive predictive value is 25%-50%but negative predictive value is 90%-95%,thus if test is negative,patient is at low risk.39Electrophysiologic Testing Cathete

26、rs are placed in RA,AV node,Bundle of HIS,right ventricle,and coronary sinus(to monitor LA and LV).Used to evaluate cardiogenic syncope of unknown origin,symptomatic SVT,symptomatic WPW,and sustained v-tach.*Ablative therapy is beneficial in AV node reentry,WPW,atrial tachycardia,a-flutter,and some

27、v-tach.Complication is 1%40Management Physical maneuvers,Medications,Electricity conversion,or Electro-or cryo-cautery.The method of cardiac rhythm management depends firstly on whether or not the affected person is stable or unstable41Therapy Principal Pathogenesis therapy Stop the arrhythmia immed

28、iately if the hemodynamic was unstable Individual therapy42Physical maneuvers(vagal maneuvers)A number of physical acts can increase parasympathetic nervous supply to the heart,resulting in blocking of electrical conduction through the AV node.This can slow down or stop a number of arrhythmias that

29、originate above or at the AV node43Anti-arrhythmia Agents Anti-tachycardia agents Anti-bradycardia agents44Anti-tachycardia agents Modified Vaugham Williams classificationqI class:Natrium channel blockerqII class:-receptor blockerqIII class:Potassium channel blockerqIV class:Calcium channel blockerq

30、Others:Adenosine,Digital45 Phase 1 快速复极初期：钾离子外流 Phase 0 快速或上升钠离子内流入进入细胞进行除极 Phase 2 平台期:持续的钠离子内流和缓慢钙离子内流和钾离子外流 Phase 3 快速复极末期:钾离子外流 Phase 4 静息期5 Phases心肌细胞的动作电位Classification of AADs类类别别 亚亚 类类 电电 生生 理理 效效 应应 代代 表表 制制 剂剂 新新 制制 剂剂 传导传导速度速度 不应不应期期 Ap时时限限 47其它药物包括：洋地黄类(临床上称之为第五类)以及新斯的明、甲氧胺、氯化钾、硫酸镁、ATP等抗

31、缓慢心律失常的药物，包括：拟交感胺类、阿托品类、碱性药物等 Clinical usage:Ia class Guinidine Procainamide Disopyramide:Side effect:like M-cholinergic receptor blocker Less use in clinic 48Clinical usage:Ib class Lidocaine MexiletinePerfect to ventricular tachyarrhythmia49Clinical usage:Ic class Moricizine PropafenoneCan be used

32、 in ventricular and/or supra-ventricular tachycardia and extrasystole.50Clinical usage:II class Propranolol:Non-selective Metoprolol:Selective 1-receptor blocker,Perfect to hypertension and coronary artery disease patients associated with tachyarrhythmia.-receptor blocker51Clinical usage:III class A

33、mioarone:Perfect to coronary artery disease and heart failure patients Sotalol:Has-blocker effect Bretylium Potassium channel blocker,extend-spectrum anti-arrhythmia agent.52Clinical usage:IV class and Others IV class:qVerapamilqDiltiazem Others:qAdenosinebe used in supraventricular tachycardia53Ant

34、i-bradycardia agents-adrenic receptor activatorqIsoprenalineqEpinephrine M-cholinergic receptor blockerqAtropine Non-specific activatorqAminophylline54Proarrhythmia effect of antiarrhythmia agents Ia,Ic class:Prolong QT interval,will cause VT or VF in coronary artery disease and heart failure patien

35、ts III class:Like Ia,Ic class agents II,IV class:Bradycardia55Non-drug therapy Cardioversion:For tachycardia especially hemodynamic unstable patient Radiofrequency catheter ablation(RFCA):For those tachycardia patients(SVT,VT,AF,AFL)Artificial cardiac pacing:For bradycardia,heart failure and malignant ventricular arrhythmia patients.5657