心电图课件：Electrocardiogram (ECG) (2)

1、,Electrocardiogram (ECG),Arrhythmias,Review,Four characteristics of cardiac cells Automaticity : SA node is the most automatic SA node 60-100 bpm ; AV junction 40-60 bpm ; His bundle 25-40 bpm Conductivity : AV node is the slowest; Purkinje fibers is the fastest. Excitability：absolute refractory per

2、iod relative refractory period Contractility,Arrhythmias,Stimulus Genesis Abnormalities Sinus Arrhythmias: 1)Sinus Tachycardia 2)Sinus Bradycardia 3)Sinus Arrhymia 4)Sinus Pause Ectopic Rhythms: Passive ：Escape Beats and Escape Rhythm Initiative：1)Premature Contraction (atria, AV junction, ventricle

3、s) 2)Tachycardia(atria, AV junction, ventricles) 3)Flutter and Fibrillation (atria, ventricles) Stimulus Conduction Abnormalities Physiological Conduction Disorder Pathological Conduction Block: Sinoatrial Block, Intraatrial Block, Atrioventricular Block, Intraventricular Block, Unexpected Conductio

4、n Conduction Pathways Abnormality: Wolff-Parkinson-White,Sinus Rhythms,ECG of Sinus Rhythms Sinus rhythm must originate in the sino-atrial node.Regularly recurring sequences of P waves, QRS complexes, and T waves. P-P or R-R interval establishes a specific interval which should not vary more than 0.

5、12 second.,Sinus Rhythms,The P wave is upward in lead I,II, avF,V4-6 and downward in lead avR. The PR interval0.12 second. Heart rate between 60 and 100 beats per minute. 50-95 bpm（male） 55-95 bpm（female）,Sinus Arrhythmias,Sinus Tachycardia1). 1 、2、3 2).Heart rate exceeds 100 beats per minute . 2. S

6、inus Bradycardia 1).1、2、3 2).Heart rate is less than 60 beats per minute.,Physiologic ExerciseStrong emotionPain Anxiety states Other factorsDrugs: Epinephrine, Atropine Food: Tea, coffee, Alcohol, Tobacco,PathologicFeverHyperthyroidismHemorrhageShockAnemiaInfectionCongestive heart failureMyocarditi

7、sHypoxia,Factors Associated with Sinus Tachycardia,Common Causes of Sinus Bradycardia,Physiologic : Laborers and trained athletes Emotional states leading to syncope Sleep High Carotid sinus pressure, eyeball pressure, intracranial pressure Pathologic : Systemic disease Obstructive jaundice Obstruct

8、ive diseases of the intestine, kidney or bladder During convalescence after some diseases marked by fever (e.g. influenza) Myxedema Myocardial infarction (inferior wall or atrial infarction) Drug : Digitalis, Morphine, Quinidine, Propranolol,3.sinus arrhythmia 1) 2、3、4 2) P-P or R-R interval varies

9、in duration by at least 0.12 second,Sinus Arrhythmias,Common Causes of Sinus Arrhythmia,Active rheumatic fever Infectious diseases Atelectasis Chronic adhesive pleuritis Intracranial tension Digitalization Autonomic nerve dysfunction (It is normal in children and young adults.),Sinus Arrhythmias,Sin

10、us Arrhythmia Note: It varies with the phases of respiration, the Sinus rate increasing with inspiration and decreasing with expiration.,Sinus Arrhythmias,4.Sinus Pause There is no sinus P wave in ECG suddenly. The long interval is not times as normal P-P interval. After a sinus pause, escape beats

11、or escape rhythm often appear.,Ectopic Rhythms,Escape Beats or Escape Rhythm Escape beats : 1 or 2 beats Escape rhythm : continual 3 or more than 3 beats.,Premature beat,The terms “premature beat”, “premature contraction”, “premature systole”, or “extra systole” indicate that the atria ,AV junction,

12、 or ventricles are stimulated prematurely.,Premature beat,These premature beats are called “atrial premature beats” when they arise in some portion of the atria . AV junctional premature beats arise in the AV junction. Ventricular premature beats arise in one of the branches of the bundle of His ,th

13、e Purkinje network , or the ventricular muscle.,Premature beat,1. Ventricular premature beats 1).The QRS complex is premature ,is 0.12second or more wide ,and is aberrant, notched ,or slurred .It is associated with a T wave that usually point in a direction opposite to the main deflection of the QRS

14、 complex.2).The premature QRS complex is not preceded by a P wave.,3).A ventricular premature beat is often followed by a fully compensatory pause(the sum of the R-R intervals including the pre-premature beat and the post-premature beat interval equals the sum of two normal R-R intervals),Premature

15、beat,Premature beat,4).Ventricular premature beats that arise from a single focus show a similar shape and usually a similar coupling interval (distance from the preceding normal QRS complex to the premature ventricular beat) in any lead.,Premature beat,5).Occasionally, a ventricular premature beat

16、will occur simultaneously with the apex of the preceding T wave.This is called R on T phenomenon. When this occurs ,it may be a precursor of a ventricular tachycardia. Note: multifocal ventricular premature beat (VPB) and multiformed VPB,I,II,III,aVR,aVL,aVF,窄QRS和宽QRS替,1 sec,Bigeminy,Premature beat,

17、2.Atrial premature beats1).A premature P wave is present . It may be superimposed on the preceding T wave because it is premature. The premature P wave is usually followed by a QRS complex and a T wave. Occasionally, it is not followed by a QRS complex and a T wave .(blocked atrial premature beat).2

18、).The QRS and T wave that follow the premature P waves usually resemble the other QRS and T waves in the same lead.,Premature beat,3).The P-R interval of the atrial premature beat is usually longer than the normal PR intervals in the ECG.4).An atrial premature beat is often followed by a noncompensa

19、tory pause.,Premature beat,5).The ventricular complex is usually normal but may be aberrant in form if the atrial premature beat coincides with the refractory period of the previous ventricular beat .The aberrant QRS is called aberrant conduction.,3. AV Junctional premature beats 1).A premature AV j

20、unction P wave is followed by a QRS and T wave.2).The AV junction P waves in avR become upward .The P waves in II,III, and avF is downward.The PR interval is usually less than 0.12second ,if the P waves is before the QRS complexes. The P waves may appear after the QRS complexes (RP0.20s) or may be h

21、idden within the QRS complex.3).An AV junctional premature beat is followed by a fully compensatory.,Premature beat,Ectopic tachycardia,Paroxysmal tachycardia is commonly seen. The paroxysmal tachycardia can be divided into two main groups. Paroxysmal Supraventricular (atria and AV junction) tachyca

22、rdia Paroxysmal ventricular tachycardia,Ectopic tachycardia,1.paroxymal supraventricular tachycardiaECG :1).Heart rate is regular rhythm with a rate of 160-250 per minute.2).The QRS complex in form is usually normal.3).The P wave is not easy to be seen.4).With abrupt onset and abrupt terminal.,2. pa

23、roxysmal ventricular tachycardia1).The QRS complexes are 0.12 second or wider , are aberrant ,and are followed by aberrant ST segments and T waves.2) Ventricular rate is between 140 and 200/minute and regular rhythm or slightly irregular.3).The P waves have no relation to the QRS complexes.4).Fusion

24、 beats or ventricular capture are present.5).Sometimes, P-P interval R-R interval. but the P-R is no relation.,Ectopic tachycardia,II,Torsade de pointes, TDP,Meaning “twisting of the points” A specific form of polymorphic ventricular tachycardia. Important because of its diagnostic and therapeutic i

25、mplications. The direction of the QRS complexes appears to rotate cyclically, pointing downward for several beats and then twisting and pointing upward in the same lead. It occurs in the setting of delayed ventricular repolarization, evidenced by prolongation of the QT Intervals or the presence of p

26、rominent U waves.,Torsade de pointes, TDP,Drug : quinidine and related antiarrhythmic agents Electrolyte imbalances : hypokalemia, hypomagnesemia Severe bradyarrhythmias : complete heart block Miscellaneous factors : liquid protein deits Hereditary long QT syndromes It sustained several seconds or s

27、everal tens of seconds. It usually recurs or change in ventricular fibrillation.,Flutter and Fibrillation,The flutter and fibrillation arise from excitable ectoptic focus in the atria and ventricle and with a rapid rate and appropriate conduction block. Thus ,They are easily caused by a reentry.,1.

28、Atrial Flutter1).There are no P waves in ECG 2).Presence of saw-tooth flutter wave (F waves).3).F waves always uniform in size ,shape and frequency.4).Regular atrial rhythm with a rate of 250-350 per minute.5).Ventricular response of 1:1,2:1,3:1,4:1,or higher.6).Absence of isoelectric line.,Flutter

29、and Fibrillation,Flutter and Fibrillation,2. Atrial Fibrillation1).Absence of P waves2).P waves replaced by f waves.3).f waves :irregular in size ,shape ,and spacing. Rate between 350 and 6004). Irregular ventricular rhythm, best seen in , ,avF，V1 or V2.,Flutter and Fibrillation,3.Ventricular Flutte

30、r and Fibrillation Note ： Ventricular Flutter and Fibrillation are fatal.,Flutter and Fibrillation,ECG Ventricular Flutter : Sine wave,150-300beats/min. Ventricular Fibrillation : Irregularity of shapes, amplitude and frenquency. Impossibly recognize QRS complexes, ST segments and T waves. If amplit

31、udes of ventricular fibrillation waves are less than 0.2mV, it prognosticates a tiny chance for survival.,AtrioVentricular(AV) Heart Block,AV Block or AVB AV junction acts as a bridge.,PR interval is a measure of the lag.In adults, the normal PR interval is between 0.12 and 0.2 second.,AVB,AV block,

32、 or heart block, exists when conduction of the stimulus from the atria to the ventricle through the AV node is slowed or blocked. The AV block may be transient ,intermittent ,or permanent .It may be incomplete or complete. A patient may show various types of AV block in one ECG.,First Degree Heart B

33、lock (I AVB）,IAVB is prolongation of the atrio-ventricular conduction time .ECG:prolonged P-R interval 0.20sec in adults 0.22sec in old adults. The difference of P-R interval between two times is more than 0.04 second. Note:P-R interval varies with heart rate and age.,What Is This Rhythm?,Second Deg

34、ree Heart Block (IIAVB),1).Mobitz Type I (Wenckebach phenomenon) (1)The P-R interval becomes longer and longer (2)The R-R interval gets shorter and shorter, until there is a blocked or nonconducted ventricular beat with a long pause, then an escape rhythm or beat resumes.,Second Degree Heart Block(I

35、IAVB),2). Mobitz Type II Mobitz II is characterized by failure of conduction of one or more sinus beats to the ventricle .There is a fixed numerical relationship between atrial and ventricular impulses,which may be 2:1 or 3:1 or 4:1 . Mobitz II blocks become progressive worse until a complete heart

36、block is established. Thus ,mobitz Type II require a pacemaker, whereas mobitz I does not require a pacemaker, since it does not progress to complete heart block.,Third degree or Complete AV Block (IIIAVB),1).The atrial and the ventricular rhythms are absolutely independent of one another .2).There

37、is no P-R to QRS relationship.3).The atrial rate is more rapid than the ventricular rate.4).Regular P-P interval.5).Regular R-R interval. 6).QRS is 0.12sec or longerer.VR is 36 beats per minute or less (20-40 beats/mim) . QRS is less than 0.12sec.VR is between36 to 60 beats per min(40-60beats/min).,

38、What Is This Rhythm?,Diagnose AVB,Step 1:Are there P waves? Step 2: Are there QRS complexes? Step 3: Have they any relationships?,Example,Sinus rhythm,III AVB,Bundle branch block,The ventricular conduction system is composed of two major divisions.the right bundle branchthe left bundle branch,Right

39、Bundle Branch Block(RBBB) 1).QRS 0.12 sec or wider2).rsR(M)pattern in V1and V2 and deep ,wide S wave in ,V5-6.3).The ST segment is slight depressed with negative T waves When incomplete RBBB is present ,the pattern is similar, but the QRS width is less than 0.12sec.,Bundle branch block,2. Left Bundl

40、e Branch Block(LBBB) 1).QRS 0.12sec or more .2).absent q waves in I,V5 and V63).wide ,notched,or slurred R waves in V5-6 with depressed ST segments,downward T waves.4).wide QS or rS patters with elevated ST segments and upward T waves in V1-2.When incomplete LBBB in present ,the pattern is similar ,but the QRS width is less than 0.12 second.,Bundle branch block,3. Left anteri