Cardiac arrhythmia

A cardiac arrhythmia is any abnormal heart rate or rhythm

Tachycardia When conduction is normal and the rate is greater than 100bpm, then the rhythm is called sinus tachycardia.

Bradycardia When conduction is normal and the rate is smaller than 60bpm, then the rhythm is called sinus bradycardia.

Premature beats Premature Atrial Ectopics Premature Ventricular Ectopics Premature Junctional Premature Beat

Atrial Ectopics The beat is caused by the premature contraction of a muscle within the atrial myocardium.

房性期前收缩 提前出现一个变异的P’波，QRS波一般不变形(室上性)，P’-R>0.12s，代偿间歇常不完全。

Ventricular ectopics The beat is caused by the premature contraction of a muscle within the ventricular myocardium [maiEu5kB:diEm]n. 心肌( 层)

室性期前收缩 1. 提前出现的QRS-T波群，其前无相关P波； 2. 提前出现的QRS波形态异常，时限通常为0.12s或以上； 3. ST段、T波与QRS波群主波方向相反； 4. 期前收缩后可见一完全代偿间歇

Paroxysmal Tachycardia Supraventricular tachycardia Ventricular tachycardia

阵发性心动过速 阵发性心动过速(paroxysmal tachycardia)是一种阵发性快速而规律的异位心律，是由三个或三个以上连续发生的期前收缩形成，根据异位起搏点的部位，可分为房性、房室交界性和室性阵发性心动过速。由于房性与房室交界性阵发性心动过速在临床上常难以区别，故统称为室上性阵发性心动过速，简称室上速。

Supraventricular tachycardia Also termed atrial tachycardia, this is a normal morphology 【mC:5fClEdVi】 n.生物形tachycardia which is not driven by the SA node.The patient may feel dizzy,attack can last for a few beats or for many hours.

室上性：心率160-250次/分，节律规则 QRS波形态及时限正常 不容易辨认出P波 起止突然

Ventricular tachycardia Usually initiated by premature ventricular complexes 合成体ventricular tachycardia is continued by re-entry mechanisms.

室性：三个或三个以上连续并迅速出现的室性期前收缩 QRS波形态畸形，时限大于0.12秒，有继发ST-T改变，T波方向与QRS主波方向相反 心率140-220次/分，心律不规则 如出现P波，P波与QRS 波无关，出现房室分离现象 常可见到心室夺获或室性隔离波——是确诊室性心动过速的最重要依据

扑动与颤动 当自发性异位搏动的频率超过阵发性心动过速的范围时，形成扑动或颤动。根据异位搏动起源的部位不同，可分为心房扑动与颤动(atrial flutter and atrial fibrillation)；心室扑动与颤动(ventricular flutter and ventricular fibrillation)。心房颤动是仅次于期前收缩的常见心律失常，远较心房扑动多见。心室扑动与颤动是极危重的心律失常。

Atrial flutter Atrial flutter usually begins with a premature beat and may be supported with a reentry mechanism or a single ectopic focus, creating a regular rhythm of 240~350bpm.

Atrial fibrillation The most common supraventricular rhythm,atrial fibrillation,is usually due to reentrant excitation within the atria with multiple reentry circuits.

房扑 ：P波消失，代之以250—350次/分间隔均匀、振幅相等、形状相似的F波；QRS波群与F波成某中固定的比例，最常见的比例是2：1； QRS波形态一般正常 房颤 ：P波消失，代之以350—600次间隔不均匀，振幅不等，形状不同的f波；QRS波群间隔绝对不规则；QRS波形态一般正常

心房扑动 心房颤动

Ventricular fibrillation Ventricular fibrillation is a form of cardiac arrest during which ventricular contractions are rapid,irregular and ineffective.

室扑： 为均匀、连续的大幅度的正弦波图形，其频率为150-300次/分，难以区分QRS—T波群

心室扑动 心室颤动

Blocks First degree atrioventricular block Second degree atrioventricula bolck morbitzⅠ（wenckebach phenomenon） morbitzⅡ（periodic block） Third degree (complete) Atrioventricular block

First degree atrioventricular block Each wave of depolarization that originates in the sinoatrial node is conducted to the ventricles and there is a delay in conduction at the junctional area.

房室传导阻滞 心电图特点： (一)  第一度房室传导阻滞 P-R间期大于0.20s，无QRS波群脱落

Second degree atrioventricular block Sometimes excitation completely fails to pass through the atrioventricular node or the bundle of His(希氏束).when this occurs intermittently second degree atrioventricular block is said to exist.

Mobitz Ⅰ（wenckebach phenomenon） The PR interval gets longer until an impulse is not conducted due to the refractory state of the bundle of His.This cycle is then repeated(and known as a Wenckebach phenomenon)

二度房室传导阻滞 Ⅰ型： (1) P-R间期逐渐延长，直至QRS波群脱落； (2) 相邻的R-R间期逐渐缩短，直至P波后QRS波群脱落； (3) 包含QRS波群脱落的R-R间期比两倍P-P间期短； (4) 最常见的房室传导比例为4:3或5:4

Mobitz Ⅱ（periodic block） Most beats are conducted with a constant PR interval,but occasionally there is an atrial contraction without a subsequent ventricular contraction.

二度房室传导阻滞 Ⅱ型： (1)下传的搏动中，P-R间期固定，可正常亦可延长； (2)有间歇性的QRS波群脱落，常呈2: 1或3:1

Third degree(complete) atrioventricular block Complete heart block occurs when atrial contraction is normal but no beats are conducted to the ventricles.The atrial rhythm,unless an accessory pathway that conducts antegrade is present.

三度房室传导阻滞 1.P-P间隔相等，R-R间隔相等，P波与QRS波群无关 2.P波频率大于QRS波频率 3.QRS波群形态取决于阻滞部位。阻滞部位高者，QRS波群呈室上性；阻滞部位较低者，QRS波群增宽

Third degree(complete) atrioventricular block

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