内科学课件：07 心律失常 8年制

1、心律失常（Cardiac Arrhythmia),Mechanism of arrhythmia,Property of cardiac elctrophysiology 兴奋性（Excitability) 自律性(automaticity) 传导性(Conductivity),Excitability,Excitability indicates that myocardial cell has electrical activity when it is stimulated Electrical activity of single myocardial cell is called a

2、ction potential(AP) Electrical activity of whole heart makes ECG,0,-60,-90,+20,Threshold voltage,mv,0,1,2,3,4,ARP,ERP,RRP,Super-conductive period,ARP: Absolute Refractory period; ERP: Effective Refractory period; RRP: Relative Refractory period,Conductivity,Electrical impulse can conduct in myocardi

3、al tissue bidirectionally Normal conduction pathway： sinus nodeintranode bundle atrioventricula node and intraatrial bundleHis bundleright and left bundle branch(including left anterosuperior and posteroinferior)Purkinje fibermyocardium,automaticity,Cells spontaneously discharging (spontaneous AP, d

4、iastolic depolarization) Automaticity increases from high to low as follows: Physiological status：SN、AVN、HIS、Purkinje pathological：diseased myocardial and conductive tissue, etc.,Property of normal rhythm,Impulse from SN Heart rate is within 60100/min Regular rhythm，PP interval0.12s PR interval is b

5、etween 0.120.20s，QRS complex duration0.10s Frontal axis within -30110It is considered as arrhythmia if any item above is not matched,Mechanisms of arrhythmogenesis,Enhanced automaticity Triggered activity Automatic cells diminish or malfunction, Dysfunction of conductive tissues Reentry,Mechanisms o

6、f arrhythmogenesis(1),Enhanced automaticity Endogenous or exogenous catecholamine increasing Abnormality of acid, basic , electrolyte balance Ischemia, hypoxia Mechanical stretch drugs Disturbance of nerve and liquid modulation,Mechanisms of arrhythmogenesis(2),Triggered activity Depolarizing oscill

7、ations of membrane voltage induced by abnormal inward Na+ current (one or more preceding AP)during earlier or later reporlarization, ie, After depolarization Early depolarization Delayed depolarization,Mechanisms of arrhythmogenesis(3),Automatic cells diminish or malfunction, such as sick sinus synd

8、rome Dysfunction of conductive tissues, such as sinoatrial block, atrioventricular block or bundle branch block as well as abnormal pathway,Mechanisms of arrhythmogenesis(4),Reentry prerequisite of reentry Conduction inconsistency of anatomy or physiology Single directional conduction blocking Delay

9、ed conduction Initial blocking area recovers excitability (reentry cycle length great than refractory period of the blocking ),Classification of cardiac arrhythmias,Classified on property of electrical activity Abnormality of impulse and conduction Classified on heart rate, rapid or slow Rapid or sl

10、ow arrhythmias Classified on clinical manifestation, mild or sever Fatal or nonfatal High risk or low risk Classified on origin of arrhythmias,Method of diagnosing arrhythmia and its evaluation,Symptom Caused by abnormal contractile：palpitation, discomfort, beating stop, etc. Induced by cardiac outp

11、ut decreasing：chest compressing and pain, dizziness, presyncope, syncope, short of breathless Factors related to symptom: medications, diet, emotion, infection, etc.,Method of diagnosing arrhythmia and its evaluation,Sign Changing of rhythm : slow or fast,regular or irregular Intensity of heart soun

12、d：S1 muffle or loud，cannon sound Relation between carotid vein wave pulse and heart rate,and changing of blood pressure,Method of diagnosing arrhythmia and its evaluation,Electrocardiogram Most valuable: evaluating arrhythmia type, property, prognosis, etc. Dynamic Electrocardiogram(Holter) Most val

13、uable: assessing arrhythmia type, numbers, distribution, property, prognosis. Evaluating clinical significance, effects of treatment, etc.,Method of diagnosing arrhythmia and its evaluation,Esophagus electrocardiogram Differentiating SVT from VT，understanding mechanism of SVT. Semi-invasive.,Method

14、of diagnosing arrhythmia and its evaluation,Electrophysiologic study(EPS) Classical way of researching arrhytnmias. Invasive Assessing function of SN Sinus node recovery time, SNRT Sinoatrial conduction time, SACT Assessing AV conduction Analyzing mechanisim of tachyarrhythmias Evaluating unknown sy

15、ncope,Method of diagnosing arrhythmia and its evaluation,Exercise Electrocardiogram Suitable for some of arrhythmias, such as VT Others Average signal technique，such as late potential(LP), QT dispersion, T wave alteration used for evaluating prognosis of ventricular arrhythmia,Specific arrhythmias,R

16、apid arrhythmias Premature contraction Atrial, junctional, ventricular Tachyarrhythmias Sinus, atrial, supraventricular, junctional, ventricular, atrial flutter and fibrellation Bradyarrhythmias Disease of sinus, AV node or bundle branch,Specific arrhythmias,Two syndromes Preexciting syndrome Relate

17、d with rapid arrhythmias Sick sinus syndrome (SSS) Related with slow arrhythmias,sinus arrhythmias,Sick sinus syndrome,Features of ECG(1) Serious persistent bradycardia (often 50bpm) Brady-tachy syndrone, recurrent episode of both bradyarrhythmia and supraventricular tachycardia (AF, AFL, SVT) under

18、 basis of bradyarrhythmia, there is often long asystole after rapid arrhythmias stop, which can cause syncope or presyncope,Sick sinus syndrome,Features of ECG(2) Frequent sinus arrest or exit block with slow HR Both of sinoatrial and AV node are diseased escape interval 2s, or slow and persistent A

19、FAFL, or slow escape rhythm,Sick sinus syndrome,Etiology Intrinsic ：sinus node itself is involved, e.g. ischemia, regressive degeneration, infiltration of other cells or tissues Extrinsic ：high vagal tone, hyperkalemia, antiarrhythmics most frequent etiology are regressive degeneration and CHD,Sick

20、sinus syndrome,Symptoms Ischemia of brain, heart, kidney Adams-Stokes syndrome Diagnosis Typical ECG patterns Symptoms is related with ECG changings Holter, provoking test, treadmill and finally electrophysiological study for the suspected. Holter is most valuable,Sinus standstill,Features PP interv

21、al elongates abruptly, basically at sinus bradycardia, which is not common multiples of basic PP interval Escape beat or rhythm is common seen Symptoms is depend on duration of standstill Symptomatic treatment, pacemaker is ultimate choice,sinoatrial block,Classification of ECG First degree SAB cant

22、 be seen on ECG Third degree SAB cant be differentiated from sinus standstill Second degree SAB is divided into two subtype, i.e. type I and type II second degree SAB Symptoms and therapy are same as sinus standstill,Type I Second degree SAB,Features of ECG PP interval progressively shortens until n

23、ext P wave fails to occur The long PP interval that normal regular PP interval,Type secondary degree SAB,Features of ECG P wave is lost abruptly, followed by long pause The duration of the pause takes the form of 2:1, 3:1 AV conduction Escape beat or rhythm can been seen,Sinus tachycardia,Clinical f

24、eatures Very common. Etiology including sympathetic execitation, excise, avtive infection, blood loss, hypoxia, heart failure, etc. Palpitation or chest discomfort are often complained Etiological treatment,Atrial arrhythmias,Premature atrial contraction,Features of ECG Premature P wave followed by

25、near normal QRS complex QRS complex is similar to it from sinus node with incomplete compensatory pause Sometimes, PR interval is prolonged, Premature P wave not conduct to the ventricles, or aberration in ventricle, full compensatory pause can be seen,Premature atrial contraction,Clinical features

26、Common seen, provoked by variety of factors, e.g. infection, inflammation, ischemia, tobacco, alcohol etc. it is more common in the elderly Symptom is related to prolonged compensatory pause, increased contraction, frequent PAC and sensitivity of patients On auscultation, irregular beating, longer i

27、nterval, increased S1 Treatment aim for etiology except obvious symptom antiarrhythmics can be given,Automatic atrial tachycardia,Features Less common. Most have underlying diseases, HR is around 130 bpm, 200 bpm less seen P wave is not as same as sinus one, PR interval changing with slightly irregu

28、lar rhythm AV block with different ratio can be seen “Warm-up” can be seen at its initial attack Etiological or symptomatic treatment, RF also plays a role,chaotic atrial tachycardia,Features Rare, most having basic disease HR is between 100-130 bpm, at lest two kind P wave can be seen PR and PP int

29、erval are changing, P not conducting sometimes, isoelectrical line between PP interval can be seen, precursor of atrial fibrillation Etiological or symptomatic treatment，antiarrhythmics with caution,Atrial flutter(AFL),Features of ECG P wave disappears, substituted by regular saw-like F wave with it

30、s rate between 220350 bpm Ventricular response (AV ratio) is usually 2:1, sometimes 4:1 or irregular Stimulation of vagus nerve or exercise may decrease or increase AV ratio with multiple Usually AFL is due to reantry around tricuspid ring, and tend to become AF,Atrial flutter(AFL),Clinical features

31、 HR is usually around 150 bpm which represents AV ratio is 2:1，may having underlying diseases Tiny and rapid jugular pulses can be seen with its rate beyond 300 bpm Similar manifestation to it in atrial fibrillation(AF) Rate or rhythm control depends on clinical presentation,Atrial fibrillation(AF),

32、Features of ECG No P wave, replaced by rapid, chaotic and tiny atrial waves with its rate of 350600 bpm Ventricle response is irregularly due to AV delay, irregular rates with normal QRS complex, but individual QRS complex may slightly different,Etiologies of atrial arrhythmias,Cardiac Degeneration,

33、 ischemic, myocarditis, enhanced load due to variety of heart diseases, hypertension, post CABG, preexciting syndrome, lone AF Non cardiac Alcohol abuse, hyper- or hypothyroidism, alteration of vagal or sympathetic tone, COPD, pulmonary embolism, diabetes, sepsis,Atrial fibrillation,Clinical feature

34、s Common with aging as well as those with underlying diseases Symptomatic severity depends on HR , AF duration, underlying heart disease Tend to embolism because of thrombosis in atria May have long cardiac arrest after paroxysmal AF stops,Atrial fibrillation,Clinical features With stethoscope, palp

35、ating artery pulse and watching jugular pulse, near all most of AF can be diagnosed with confidence Amphasisng prevention embolism Rate or rhythm control depends on clinical presentation,AF Classification based on features of episode:,New classification First-detected episode Recurrent paroxysmal (s

36、elf-terminating, 7 d) permanent Old classification paroxysmal, persistent and permanent AF,Junctional arrhythmias,Junctional premature contraction,Features of ECG Premature retrograde P wave(may not seen) The P usually in front of QRS complex ( may follows QRS one), PR0.10s，RP0.20s Most of them with

37、 complete compensatory pause, QRS complex normal or in aberration,Junctional premature contraction,Clinical features Rather common. Most occurred with organic heart disease Similar findings to atrial one on auscultation Symptom is similar to that of atrial ones Treatment is not necessary unless obvi

38、ous symptom,Nonparoxysmal junctional tachycardia,Features Less common. Most have underlying diseases, digitalis side effect Attack gradually, AV dissociation common, QRS complex usually normal HR between 70-130 bpm, hemodynamics relatively changing less Eiological treatment, antiarrhythmics is not r

39、ecommended,Supraventricular paroxysmal (AV nodal reantrant) tachycardia,Features of ECG HR between 160250bpm, absolute regular, QRS complex narrowing (exception of aberration) Occasionally, retrograde P wave seen Reentry(AV node, AV) is majority of mechanism,Supraventricular paroxysmal tachycardia,C

40、linical features Most without organic heart disease, common seen Attack with sudden initiation and termination, maintaining short for minutes or long for hours. Palpation is mainstream of symptom Hypotension, collapse is far less than VT Good reaction to treatment, e.g. vagal maneuvers, antiarrhythm

41、ics. Radiofrequace is best way for radical cure,Pre-excitation or Wolf-Parkinson-white(WPW) syndrome,Features of ECG PR interval 0.12 s or normal, wave in onset of QRS complex which result in widened QRS complex followed by secondary ST-Tchange PR interval is 0.12 s，but QRS complex is normal(short P

42、R syndrome or LGL (lown-Ganong-Levine syndrome),Features of Preexcitation syndrome, P-R=0.12s, wave Secondary ST-T change STV often seen,Preexcitation syndrome,Clnical features Part of patients have onset of SVT, AF, AFL, its mechanism is reentry There are several types of preexcitation, e.g. persis

43、t, intermittent, latent, concealed It is predisposed to sudden death if refractory period of accessory pathway is 270ms Therapy is as same as it in STV, but digitalis, varapamil, -blocker are forbidden in AF attack,Ventricular arrhythmias,Ventricular premature contraction,Features of ECG Premature Q

44、RS complex with no preceding related P wave QRS complex is bizarre in shape with full compensatory pause( insert one exception) AV dissociation can be seen,Ventricular premature contraction,Clinical features Most common. Seen at organic heart diseases, some of it in AMI or myocardiopathy can induce

45、fatal arrhythmia Similar features to other premature complex on auscultation. Palpitation is a common complain Treatment regimen on basis of clinical manifestation,Ventricular paroxysmal tachycardia,Features of ECG HR between 150200 bpm，regular rhythm QRS complex bizarre and widen AV dissociation, v

46、entricular fusion and capture,Ventricular paroxysmal tachycardia,Clinical features Often with organic diseases, inducing hemodynamics deterioration causing remarkable symptoms Both sustained and non-sustained VT seen in clinical It should be stopped as soon as possible(with antiarrhythmics or DC car

47、dioversion) Varapamil, adenosine, -blocker are effective for some specific VT,Torsade de pointes(TDP),Features Congenital (recurrent syncope, deafness, long QT, i.e long QT syndrome) Acquired (drugs e.g. quinidine, electrolyte disturbance, high degree AVB, etc.), at least 80% is acquired in clinical

48、 Long QT is common, often VPC at late diastole inducing TDP TDP displays as peak of QRS complex reverses along isoelectric line, causing patients syncope TDP, most of it, terminating spontaneously with several sec.,Torsade de pointes(TDP),Treatment During attack Increasing HR：atropine, pacing, isopr

49、oterenol Infusion of magnesium, potassium, lidocaine useful only in a few patients During reliefe -blocker, calcium antagonist, antiepileptic drugs Left side cervicothoracic symppathetic ganglionectomy or implantation of cardioverter-defibrillator in some refractory cases,Accelerated idoventricular

50、rhythm,Features Common in AMI, myocarditis, digitalis intoxication HR between 60120bpm, regular, QRS complex bizarre Both onset and ceasing are gradual Mild effect on hemodynamics changing Etiological treatment, antiarrhythmics with caution,Heart blocking,atrioventricular block ，AVB,Classification A

51、cute and chronic AVB The acute is mainly due to myocarditis, AMI, electrolyte abnormality and some drugs impact The chronic is mainly caused by regressive degenerative fibrosis or consequence of the acute one,1st degree AVB,Features of ECG PR interval 0.20s in adults or 0.18s in children Most of it

52、is in 0.210.35s,2nd typeAVB(Wenchebach block),Features of ECG Progressive PR interval prolongation occurs, resulting in a nonconduction P wave( the pause), the duration of the pause is two basic RR cycles RR interval progressively shortens First PR interval after the pause is shortest, AV conduction

53、 ratios usually are 3:2 or 4:3,2nd type AVB,Features of ECG PR interval is usually normal and no change P wave do not conduct suddenly or periodically, making the long pause The long pause is multiples of basic cycles,3rd degree AVB,Features of ECG AV conduction fails completely with AV dissociation

54、 Ventricular activity is maintained by an escape rhythm arising from site distal to His bundule Atrial rate ventricular rate QRS complex is broad if pace site distal to His, otherwise it is nearly normal Advanced AVB refer to that only a few P wave conducts to the ventricles, getting its same clinic

55、al significant as it in III AVB,Features of AVB,first degree AVB Seen at inflammation(myocarditis, AMI), drugs, trauma, fibrosis, increased vagus tone, etc. No symptoms,Manifestation of AVB,Second degree typeAVB Seen at high vagal tone, drugs myocarditis, AMI, etc. No remarkable hemodynamics change,

56、 may have wild symptoms A few cases may progress worse into severe AVB,Manifestation of AVB,Second degree type II AVB Almost has underlying heart diseases HR is slow and sometimes unstable Those whose blocking level is distal to His bundle are predisposed to progress into third AVB Symptoms are prom

57、inent,Manifestation of AVB,Third degree AVB Almost has underlying heart diseases HR is slow and unstable Those whose blocking level is distal to His bundle are predisposed to turn into cardiac asystole or TDP, which could cause recurrent syncope or Adams-Stokes syndrome,Manifestation of AVB,Third de

58、gree AVB On auscultation, intensity of S1 varies due to loss of AV synchrony, cannon sound(wave), S3，S4 can be heard Syncope, presyncope, chest compression heart failure, etc. are seen frequently. With high risk of sudden death,Management of AVB,First or second degree type I AVB Aim for etiology and

59、 symptoms, follow up AV conduction changing Second degree type AVB Aim for etiology and symptoms, close investigation of clinical manifestation Patients with symptomatic bradyarrhythmia should receive a permanent pacemaker,Management of AVB,Third degree AVB There is evidence that pacing can improve prognosis in these patient no matter symptomatic or asymptomatic, in acute stage, temporary pacemaker, chronic permanent,Bundle branch block(BBB),Right BBB(complete, incomplete) Left BBB (complete, incomplete) Left anterior fascic