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Dysrhythmia心律失常,Properties of cardiac tissue 心脏组织的特性,Automaticity 自律性: ability to initiate an impulse spontaneously and continuously. Excitability兴奋性: ability to be electrically stimulated. Contractility收缩性: ability to respond mechanically to an impulse. Conductivity传导性: ability to transmit an impulse along a membrane in an orderly manner.,Conduction system: a brief review传导系统,P wave begins with the firing of the SA node and represents depolarization去极化 of the fibers of the atria心房, resulting in atrial contraction心房收缩. The QRS complex represents depolarization去极化 of the ventricles心室, resulting in ventricular contraction心室收缩. The T wave represents repolarization复极of the ventricles心室, or the time at which the ventricles return to the prestimulated state.,Conduction system: a brief review,Intervals波间隔between these waves reflects the lengths of time it takes for the impulses to travel from one area of the heart to the other. The PR interval represents the period during which the impulse spreads through the atria, AV node房室结, bundle of His希氏束, and Purkinje浦肯野纤维. The QRS interval represents the time it takes for depolarization去极化of both ventricles. The QT interval represents the time it takes for complete depolarization除极and repolarization复极of the ventricles.,Dysrhythmia,Dysrhythmia is an abnormal cardiac rhythm in terms of the frequency of the impulse频率, rhythm节律, origin site起源部位, conduction velocity传导速度and excitement order激动次序.,Classification of Dysrhythmia 心律失常的分类,Abnormal impulse formation 冲动形成异常 sinus dysrhythmia 窦性心律失常 sinus tachycardia窦性心动过速 sinus bradycardia窦性心动过缓 窦性心律不齐 sinus arrest窦性停搏 ectopic rhythm异位心律 Passive ectopic rhythm被动性异位心律 Escaped 逸博 Escapedrhythm 逸博心律 Active ectopic rhythm主动性异位心律 期前收缩Premature Contraction Paroxysmal tachycardia阵发性心动过速 atrial flutter房扑， atrial fibrillation房颤 ventricular flutter室扑， ventricular fibrillation室颤,Abnormal impulse comduction 冲动传导异常 Physiological:生理性： interference and separation of AV干扰和房室分离 pathological病理性： block of SA窦房传导阻滞 block of atrial pathway房内传导阻滞 block of atrioventricular pathway房室传导阻滞 Block of bundle branch束支或分支阻滞或室内阻滞 房室间传导途径异常：WPW 预激综合征,Sinus tachycardia窦性心动过速,Clinical association: It associated with physiological stressors such as exercise, fever, pain, anxiety, hypotension, hypovolemia低血容量 , anemia, hypoxemia低氧血症 , hypoglycemia低血糖症 , myocardial ischemia, CHF, and thyrotoxicosis甲状腺毒症. It also can be affected by drugs such as epinephrine, norepinephrine, caffeine, atropine阿托品 , theophylline茶硷 , nifedipine硝苯地平 , hydralazine胼酞嗪(降压药),Sinus tachycardia窦性心动过速,Significance: The clinical significance of sinus tachycardia depends on patients tolerance of the increased HR. The patient may have symptoms of dizziness头晕, hypotension低血压may occur. Angina or an increase in infarct size may accompany persistent sinus tachycardia in the patient with MI心肌梗塞. Treatment The treatment is determined by underlying causes. In certain setting, -blocker therapy is used to reduced HR and decrease myocardial oxygen consumption.,Sinus tachycardia,ECG characteristics HR is greater than 100 bpm, rhythm is regular. The P wave is normal, precedes each QRS complex, and has a normal contour and fixed interval. The PR interval is normal and the QRS complex has a normal contour.,Sinus bradycardia 窦性心动过缓,Clinical association 临床联系: It occurs in response to hypothermia低体温 , carotid sinus massage按压颈动脉窦, increased intraocular pressure眼内压 , increased vagal tone迷走神经紧张 , and administration of parasympathomimetic拟副交感神经药drugs. Diseases states associated with sinus bradycardia are hypothyroidism甲状腺机能减退 , increased intracranial pressure颅内压 , obstructive jaundice阻塞性黄疸 and inferior wall MI.,Sinus bradycardia 窦性心动过缓,Significance意义: The clinical significance of sinus bradycardia depends on how the patients tolerates it hemodynamically. Hypotension with decreased CO may occur in some circumstances. Treatment治疗: for the patient with symptoms, administration of atropine阿托品 , and anticholinergic drug抗胆碱能药 . Pacemaker therapy may be required.,Sinus bradycardia窦性心动过缓,ECG characteristics HR is less than 60 bpm, rhythm is regular. The P wave precedes each QRS complex. The PR interval is normal and the QRS complex has a normal contour and normal length.,Premature Atrial Contraction (PAC)房性期前收缩,A PAC is a contraction originating from an ectopic focus异位病灶 in the atrium in a location other than the sinus node. It originates in the left or right atrium and travels across the atria by an abnormal pathway, creating a distorted P wave. At the AV node房室结, it is stopped (nonconducted PAC), delayed (lengthened PR interval), or conducted normally. It moves through the AV node, and in most cases, it is conducted normally through the ventricles.,Premature Atrial Contraction (PAC)房性期前收缩,Clinical association In a normal heart, it can result from stress or the use of caffeine, tobacco or alcohol. It also can result from diseases states such as infection, inflammation, hyperthyroidism甲亢, COPD, heart diseases, valvular diseases. A PAC and also be caused by enlarged atria. Significance: a PAC may be prelude前奏to supraventricular tachycardias室上性心动过速. Treatment: depends on patients symptoms. Withdrawal of sources of stimulation such as caffeine may be warranted. Drugs such as digoxin, quinidine奎尼丁, , procainamide普鲁卡因, flecainide氟卡尼 , and -blockers can be used.,Premature Atrial Contraction (PAC)房性期前收缩,ECG characteristics HR varies and rhythm is irregular. The P wave may be notched缺迹 or have negative deflection逆向的偏转, or it may be hidden in the preceding T wave. QRS is usually normal, if the QRS interval is 0.10 second or longer, abnormal conduction through the ventricle is present. The PR interval may be shorter or longer than normal PR interval, but its within normal limit.,Paroxysmal supraventricular tachycardia (PSVT)阵发性室上性心动过速,PAVT is dysrhythmia originating in an ectopic focus anywhere above the bifurcation of the bundle of His希氏束分支. PSVT occurring via an accessory pathway旁路途径is designated as orthodromic顺向or antidromic逆向性 tachycardia.,Paroxysmal supraventricular tachycardia (PSVT)阵发性室上性心动过速,Orthodromic顺向refers to anterograde顺时, or forward 向前conduction through the AV node and retrograde逆行, backward 向后conduction, through the accessory pathway. Antidromic逆向refers to the opposite: anterograde conduction顺时传导through the accessory path 旁路途径 and retrograde conduction 逆行传导through the AV node.,Paroxysmal supraventricular tachycardia (PSVT)阵发性室上性心动过速,Clinical association In the normal heart, PSVT is associated with overexertion, emotional stress, changes of position, deep inspiration, and stimulation and stimulants such as caffeine and tobacco. In a diseases state, PSVT is associated with rheumatic heart disease, Wolff-Parkinson-White (WPW)预激综合症(conduction via accessory pathways), digitailis intoxication, coronary artery disease or cor pulmonary.,Paroxysmal supraventricular tachycardia (PSVT)阵发性室上性心动过速,Significance: a prolonged episode and HR greater than 180 bpm may precipitate a decreased CO with hypotension and myocardial ischemia. Treatment: vagal stimulation迷走神经刺激: carotid massage按摩颈动脉窦or the Valsalva meneuver Valsalva动作 pharmacologic therapy: adenosine腺苷 , verapamil异搏定 , diltiazem地尔硫卓 , digitalis洋地黄 and propranolol心得安 . However, dititalis洋地黄and calcium channel blockers can cause hemodynamic collapse in WPW syndrome.,Paroxysmal supraventricular tachycardia (PSVT)阵发性室上性心动过速,ECG characteristics HR is 150 to 250 bpm and rhythm is regular. The P wave is often hidden in the preceding T wave and has an abnormal contour. The PR interval may be prolonged, shortened or normal QRS complex may have a normal or abnormal contour.,Atrial flutter 心房扑动,Atrial flutter is identified by recurring, regular, sawtooth-shape flutter waves锯齿形扑波. Atrial flutter is relatively rare dysrhythmia. Clinical association: It rarely occurs in a normal heart. In disease states, it is associated with CAD, hypertension, mitral valve disorders, pulmonary embolus肺栓塞, cor pulmoale肺心病, cardiomyopathy心肌病, hyperthyroidism甲亢 and the use of drugs such as digitalis, quinidine奎尼丁 , and epinephrine.,Atrial flutter心房扑动,Significance: high ventricular rates associated with atrial flutter can decrease CO and cause serious consequence such as heart failure, especially in the patient with underlying heart disease. Treatment: Electrical cardioversion心脏电复律may be used to convert the atrial flutter to sinus rhythm in an emergency situation. Drugs used include verapamil 异搏定, digoxin洋地黄 quinidine奎尼丁 , procainamide普鲁卡因 and -blockers.,Atrial flutter心房扑动,ECG characteristics Atrial rate is 250 to 330 bpm. The ventricular rate varies according ot the conduction ratio. In 2:1 conduction, the ventricular rate is typically found to be apporximately 150 bpm. Atrial rhythm is regular, and ventricular rhythm is usually regular. The P wave is represented by sawtooth waves锯齿波or F waves. The PR interval is available. QRS complex is normal in contour.,Atrial fibrillation心房颤动,Atrial fibrillation is characterized by a total disorganization of atrial electrical activity电生理活动without effective atrial contraction心房收缩. Ventricular response心室反应is irregular, and if the patient is untreated, the ventricular rate will be 100 to 160 bpm. The dysrhythmia may be chronic or intermitten. Clinical association: it usually occurs in the patient with underlying heart disease; it also associated with thyrotoxicosis甲状腺毒症, alcoholism, infection, gastroenteritis and stress.,Atrial fibrillation心房颤动,Significance: It often result in a decrease in CO due to ineffective atrial contractions and a rapid ventricular response. Thrombi血栓may form in the atria as a result of ineffective atrial system may occur as a complication with subsequent development of a stroke. Treatment In emergeny situation, cardioversion心脏电复律may be used to convert atrial fibrillation to normal sinus rhythm. Medication used include digoxin洋地黄, verapamil 异搏定, quinidine奎尼丁 , procainamide普鲁卡diltiazem地尔硫卓 , and -blockers, flecainide氟卡尼 , propafenone 普罗帕酮 and sotalol施太可盐酸索他洛尔 .,Atrial fibrillation心房颤动,ECG characteristics Atrial rate may be as high as 350 to 600 bpm. The ventricular rate varies from as low as 50 to as high as 180 bpm. Atrial rhythm is chaotic混乱, and ventricular rhythm is irregular. The P wave shows fibrillatory waves房颤波(f wave), but no definite P waves can be observed. The PR interval is not measurable. QRS complex usually has a normal contour.,Premature ventricular contractions室性期前收缩,Premature ventricular contractions: is a contraction originating in a ectopic focus异位节律in the ventricles. The QRS wave is usually wider than 0.12 seconds. The T wave is generally large and opposite in direction to the major deflection of the QRS complex,Premature ventricular contractions (PVC)室性期前收缩,PVC are initiated from different foci病灶appear different in contour不同轮廓from each other and are call multifocal PVCs多灶性期前收缩. When every other beat is PVC, it is called ventricular bigeminy心室二联律. When every third beat is PVC, it is called ventricular trigeminy心室三联律.,Premature ventricular contractions (PVC)室性期前收缩,Two consecutive PVCs are called couplets成对室性期前收缩. Three consecutive PVCs are called triplets. Ventricular tachycardia室性心动过速occurs when there are three or more consecutive PVCs. When a PVC falls on the T wave of preceding beat, the R on T phenomenon R波落在T波上现象 occurs and is considered to be dangerous because it may precipitate ventricular tachycardia室性心动过速or ventricular fibrillation心室颤动.,Premature ventricular contractions (PVC)室性期前收缩,Clinical association: Is associated with stimulation such as caffeine, alcohol, aminophyline氨茶碱, epinephrine and digoxin. They are also associated with hypokelemia低钾血症, hypoxia缺氧, fever, exercise, and emotional stress. Disease states associated with PVC includes MI, CHF and CAD. Significance: In heart diseases, depending on frequency, PVCs may reduce the CO and precipitate angina and heart failure. . Treatment: For treating PVCs, lidocaine 利多卡因is the drug of choice. Procainamide普鲁卡因 is the second drug of choice if lidocaine is ineffective.,Premature ventricular contractions (PVC)室性期前收缩,ECG characteristics HR varies. Rhythm is irregular because of premature beat. A retrograde逆行P wave is possible, and P wave is rarely visible because is usually lost in the QRS complex of PVC. The PR interval is not measurable. QRS complex is wide and distorted in shape, more than 0.01 second.,Ventricular tachycardia 室性心动过速,The ECG diagnosis of ventricular tachycardia is made when a run of three or more PVCs occurs. The QRS is distorted歪曲in appearance with a duration exceeding 0.12 second and with the ST-T direction pointing to the major QRS deflection. Ventricular tachycardia may be sustained持续性(lasting longer than 30 seconds) or nonsustained 非持续性(lasting 30 seconds or less).,Ventricular tachycardia,Clinical association: Is associated with acute MI, CAD, significant electrolyte imbalances, cardiomyopathy心肌病, long QT syndrome and coronary reperfusion after thrombolytic therapy溶栓治疗后冠状动脉再灌注. Is also can be observed in the patient who has not heart diseases. Significance: The appearance of ventricular tachycardia is an ominous不祥sign. It may cause a severe decreased in CO . The result may be pulmonary edema肺水肿, shock休克, and insufficient blood flow to the brain大脑血流量不足. Ventricular fibrillation心室颤动may develop.,Ventricular tachycardia,Treatment: If the patient is hemodynamically stable, treatment consists of administration of lidocaine利多卡因bolus, Procainamide普鲁卡因 is the second drug of choice if lidocaine is ineffective. If the patient is unconscious or hemodynamically unstable, immediate cardioversion心脏电复律is the recommended treatment.,Ventricular tachycardia,ECG characteristics Ventricular rate is 110 to 250 bmp. Rhythm may be regular or irregular. The P wave may be dissociated from脱离QRS complex, or it may be buried in QRS complexes or T waves. The PR interval is not measurable. QRS complex is prolonged for more than 0.10 seconds and the QRS complex is distorted.,Ventricular fibrillation心室颤动,Ventricular fibrillation is a severe derangement of the heart rhythm characterized on the ECG by irregular undulations 波动of varying contour and amplitude. This represents the firing of multiple ectopic foci异位病灶in the ventricle. Mechanically the ventricle is simply “ quivering颤抖”, and no effective contraction or CO occurs.,Ventricular fibrillation心室颤动,Clinical association: It occurs in acute MI and myocardial ischemia and in chronic diseases such as CAD and cardiomyopathy心肌病. It may occur during cardiac pacing心脏起搏or cardiac catheterization procedures心导管检查as a result of catheter stimulation of the ventricle. It may also occur with coronary reperfusion冠状动脉重新灌注after thrombolytic therapy溶栓治疗. Other clinical associations are accidental electrical shock, hyperkalemia高钾血症and hypoxemia低氧血症.,Ventricular fibrillation心室颤动,Significance: It results in unconsciousness昏迷, absence of pulse, apnea呼吸困难, and seizure癫痫. If left untreated, the patient with this condition will die. Treatment: Immediate initiation of cardiopulmonary resuscitation心肺复苏(CPR) and initiation of advanced cardiac life support (ACLS) measures高级心脏生命支持with use of defibrillation and definitive drug therapy.,Ventricular fibrillation心室颤动,ECG characteristics HR is not measurable. Rhythm irregular and chaotic. The P is not visible. The PR interval and the QRS interval are not measurable.,First degree AV block I度房室传导阻滞,First degree AV block is a type of AV block in which every impulse in conducted to the ventricles but the duration of AV conduction is prolonged. This is manifested by PR interval greater than 0.20 second. After the impulse moves through the AV node, it is usually conducted normally through the ventricle.,First degree AV block I度房室传导阻滞,Clinical association: it is associated with MI, chronic ischemia heart diseases, rheumatic fever风湿热, hyperthyroidism甲亢, vagal simulation and drugs such as digitalis, -blocker, flecainide 氟卡尼, and IV verapamil 异搏定. Significance: first degree AV block may be a precursor of high degrees of AV block. Treatment: there is no treatment for the first degree AV block.,First degree AV block I度房室传导阻滞,ECG characteristics Atrial rate is normal, and rhythm is regular. The P wave is normal. The PR interval is prolonged for more than 0.20 second. QRS complex usually has a normal contour.,Second degree AV block, Type I I型 二度房室传导阻滞,Type I AV block includes a gradual lengthening of the PR interval, and a QRS complex is droped. Type I AV block most commonly occurs in the AV node, but it can also occur in the His-Purkinje System. Clinical association: type I AV block may result from use of drugs such as digoxin or -blocker. It may also be associated with ischemia cardiac disease and other diseases that can slow AV conduction.,Second degree AV block, Type I I型 二度房室传导阻滞,Significance: is usually a result of myocardial ischemia in an inferior MI. It is almost transient and is usually well tolerated, however, it may be a warning signal预警信号of impending significant AV conduction disturbance. Treatment: if the patient is symptomatic, atropine阿托品is used to increased HR or a temporary pacemaker临时起搏器may be needed, especially if the patient has an acute MI.,Second degree AV block, Type I I型 I I度房室传导阻滞,ECG characteristics Atrial rate is normal, and ventricular rate may be slower as a result of dropped QRS complexs. Ventricular rhythm is irregular. The P wave has a normal contour. The PR interval is progressively lengthens before the nonconducted P wave occurs PR间期逐步延长，直至下一个P波受阻不能下传至心室， and a QRS complex is dropped. QRS complex has a normal contour.,Second degree AV block, Type II I I型 二度房室传导阻滞,Type II AV block : A P wave is nonconducted, and this almost always occurs when a bundle branch block is present束支传导阻滞. Type II AV block almost always occurs in the His-Purkinje system浦肯野系统. Second-degree block is a more serous type of block in which a certain number of impulse from the sinus node are not conducted to the ventricles. This occurs in ratios of 2:1 or 3:1, and so on then there are two P waves to one QRS complex, three P waves to one QRS complex.,Second degree AV block, Type II I I型 二度房室传导阻滞,Clinical association: Type II AV block is associated with rheumatic风湿性and atherosclerotic粥样硬化性heart disease, acute anterior MI, digitalis toxicity. Significance: It often progresses to third degree AV block and is associated with a poor prognosis. It is an indication for therapy with a permanent pacemaker. The reduced HR may result in decreased CO with subsequent hypotension and myocardial ischemia.,Second degree AV block, Type II I I型 二度房室传导阻滞,Treatment: Temporary treatment before insertion of a permanent pacemaker involves the use of a temporary pacemaker. Drugs such as atropine阿托品, epinephrine or dopamine多巴胺can be tired as temporary measures to increase HR until pacemaker therapy is available.,Second degree AV block, Type II I I型 二度房室传导阻滞,ECG characteristics Atrial rate is normal, and ventricular rate depends on the intrinsic rate and the degree of AV block . Sinus rhythm is regular, but ventricular rhythm may irregular. The P wave has a normal contour. The PR interval may be normal or prolonged but remains fixed on conducted beats. QRS complex widens more than 0.12 second because of bundle branch block.,Third-degree AV block三度房室传导阻滞,Third-degree AV block: is complete heart block, constitutes one form of AV dissociation房室分离in which no impulse from the atria are conducted to the ventricles. The atria are stimulated and contract independently of the ventricles. The ventricle rhythm is an escape rhythm, and focus may be above or below the bifuration of the His bundle 希氏束.,Third-degree AV block I I I度房室传导阻滞,Clinical association: is associated with fibrosis 纤维化 or calcification 钙化 of the cardiac conduction system, CAD, myocarditis, cardiomyopathy心肌炎, open heart surgery and some systemic diseases such as amyloidosis淀粉样变性and scleroderma硬皮. Significance: it almost always result in decreased CO with subsequent ischemia and heart failure. . Treatment: Tempora
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