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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
2、action 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 myocard
3、ial 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,
4、diastolic 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
5、between 0.120.20s，QRS complex duration0.10s Frontal axis within -30110 It 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
6、 of 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 osci
7、llations 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 sy
8、ndrome 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 Del
9、ayed 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
10、slow 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 ou
11、tput 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 so
12、und：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 v
13、aluable: 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.,Metho
14、d 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
15、syncope,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
16、,Rapid 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 Related with rapid arrhythmias Sick sinus syndrome (SSS) Related with slow arrhythmias,sinus arrhythmias,Sick sinus syndrome,Features of ECG(1) Serious persistent b
