A systematic approach to ECG interpretation: an efficient and safe method
心电图判读的系统性方法：一种高效安全的诊断流程

The ECG must always be interpreted systematically. Failure to perform a systematic interpretation of the ECG may be detrimental. The interpretation algorithm presented below is easy to follow and it can be carried out by anyone. The reader will gradually notice that ECG interpretation is markedly facilitated by using an algorithm, as it minimizes the risk of missing important abnormalities and also speeds up the interpretation. Note that this chapter is preceded by a comprehensive discussion in the chapter Characteristics and Definitions of the Normal ECG, and the accompanying Pocket Guide to ECG Interpretation.
心电图的解读必须始终遵循系统化方法。未能进行系统化解读可能造成不利影响。下文介绍的解读算法简单易行，适用于任何操作者。读者将逐渐发现，采用算法能显著提升心电图解读效率，既可降低遗漏重要异常的风险，又能加快解读速度。请注意，本章前文已在"正常心电图的特征与定义"章节及配套的《心电图解读袖珍指南》中进行了全面讨论。

1. Rhythm  1. 节律分析

Common findings  常见表现

• Sinus rhythm (which is the normal rhythm) has the following characteristics: (1) heart rate 50–100 beats per minute; (2) P-wave precedes every QRS complex; (3) the P-wave is positive in lead II and (4) the PR interval is constant.
  窦性心律（即正常心律）具有以下特征：（1）心率 50-100 次/分钟；（2）每个 QRS 波群前均有 P 波；（3）II 导联 P 波正向；（4）PR 间期恒定。
• Causes of bradycardia: sinus bradycardia, sinoatrial block, sinoatrial arrest/inhibition, second-degree AV block, third-degree AV block. Note that escape rhythms may arise during bradycardia. Also, note that bradycardia due to dysfunction in the sinoatrial node is referred to as sinus node dysfunction (SND). If a person with ECG signs of SND is symptomatic, the condition is classified as sick sinus syndrome (SSS).
  心动过缓的病因包括：窦性心动过缓、窦房传导阻滞、窦性停搏/抑制、二度房室传导阻滞、三度房室传导阻滞。需注意心动过缓时可能出现逸搏心律。此外，由窦房结功能障碍导致的心动过缓称为窦房结功能不全（SND）。若患者心电图显示 SND 体征并伴有症状，则归类为病态窦房结综合征（SSS）。
• Causes of tachycardia (tachyarrhythmia) with narrow QRS complexes (QRS duration <0,12 s): sinus tachycardia, inappropriate sinus tachycardia, sinoatrial re-entry tachycardia, atrial fibrillation, atrial flutter, atrial tachycardia, multifocal atrial tachycardia, AVNRT, AVRT (pre-excitation, WPW). Note that narrow complex tachyarrhythmia rarely causes circulatory compromise or collapse.
  窄 QRS 波心动过速（QRS 波时限<0.12 秒）的病因包括：窦性心动过速、不适当窦性心动过速、窦房折返性心动过速、心房颤动、心房扑动、房性心动过速、多源性房性心动过速、房室结折返性心动过速（AVNRT）、房室折返性心动过速（预激综合征，WPW）。需注意窄 QRS 波心动过速极少导致循环衰竭或虚脱。
• Causes of tachycardia (tachyarrhythmia) with wide QRS complexes (QRS duration ≥0,12 s): ventricular tachycardia is the most common cause and it is potentially life-threatening. Note that 10% of wide complex tachycardias actually originate from the atria but the QRS complexes become wide due to abnormal ventricular depolarization (e.g. sinus tachycardia with simultaneous left bundle branch block).
  宽 QRS 波心动过速（QRS 波时限≥0.12 秒）的病因：室性心动过速是最常见原因且具有潜在致命性。需注意 10%的宽 QRS 波心动过速实际源于心房，但由于心室除极异常（如窦性心动过速合并左束支传导阻滞）导致 QRS 波增宽。

2. P-wave morphology and PR interval
2. P 波形态与 PR 间期

Common findings  常见表现

• P-wave must be positive in lead II, otherwise, the rhythm cannot be sinus rhythm.
  II 导联 P 波必须为正向，否则心律不可能是窦性心律。
• P-wave may be biphasic (diphasic) in V1 (the negative deflection should be <1 mm). It may have a prominent second hump in the inferior limb leads (particularly lead II).
  V1 导联 P 波可呈双向（双相），负向波应<1mm。下壁肢体导联（尤其是 II 导联）可能出现明显的第二峰。
• P mitrale: increased P-wave duration, enhanced second hump in lead II and enhanced negative deflection in V1.
  二尖瓣型 P 波：P 波时限增宽，II 导联第二峰增强，V1 导联负向波加深。
• P pulmonale: increased P-wave amplitudes in lead II and V1.
  肺型 P 波：II 导联和 V1 导联 P 波振幅增高。
• If P-wave is not clearly visible: look for retrograde (inverted) P-waves, which can be located anywhere between the J point and the terminal part of the T-wave.
  若 P 波不明显：寻找逆向（倒置）P 波，其可能位于 J 点至 T 波终末段之间的任何位置。
• PR interval >0,22 s: first-degree AV block.
  PR 间期＞0.22 秒：一度房室传导阻滞。
• PR interval <0,12 s: Pre-excitation (WPW syndrome).
  PR 间期＜0.12 秒：预激综合征（WPW 综合征）。
• Second-degree AV-block Mobitz type I (Wenckebach block): repeated cycles of gradually increasing PR interval until an atrial impulse (P-wave) is blocked in the atrioventricular node and the QRS complex does not appear.
  二度 I 型房室传导阻滞（文氏阻滞）：PR 间期逐渐延长直至某个心房冲动（P 波）在房室结被阻滞且 QRS 波群消失的重复周期。
• Second-degree AV-block Mobitz type II: intermittently blocked atrial impulses (no QRS seen after P) but with constant PR interval.
  二度房室传导阻滞莫氏 II 型：心房冲动间歇性受阻（P 波后未见 QRS 波），但 PR 间期恒定。
• Third-degree AV-block: All atrial impulses (P-waves) are blocked by the atrioventricular node. An escape rhythm arises (cardiac arrest ensues otherwise), which may have narrow or wide QRS complexes, depending on its origin. There is no relation between P-waves and the escape rhythm’s QRS complexes, and the atrial rhythm is typically faster than the escape rhythm (both rhythms are typically regular).
  三度房室传导阻滞：所有心房冲动（P 波）均被房室结阻断。此时会出现逸搏心律（否则将发生心脏停搏），其 QRS 波群可窄可宽，具体取决于起源部位。P 波与逸搏心律的 QRS 波群之间无固定关系，且心房节律通常快于逸搏心律（两种节律通常均规则）。

3. QRS complex  3. QRS 波群

Common findings  常见表现

• Wide QRS complex (QRS duration ≥0.12 s): Left bundle branch block. Right bundle branch block. Nonspecific intraventricular conduction disturbance. Hyperkalemia. Class I antiarrhythmic drugs. Tricyclic antidepressants. Ventricular rhythms and ventricular extrasystoles (premature complexes). Artificial pacemaker which stimulates in the ventricle. Aberrant conduction (aberrancy). Pre-excitation (Wolff-Parkinson-White syndrome).
  宽 QRS 波群（QRS 时限≥0.12 秒）：左束支传导阻滞。右束支传导阻滞。非特异性室内传导障碍。高钾血症。I 类抗心律失常药物。三环类抗抑郁药。室性心律及室性期前收缩（早搏）。心室起搏器。差异性传导。预激综合征（Wolff-Parkinson-White 综合征）。
• Short QRS duration: no clinical relevance.
  QRS 波时限缩短：无临床意义。
• High voltage: Hypertrophy (any lead). Left bundle branch block (leads V5, V6, I, aVL). Right bundle branch block (V1–V3). Normal variant in younger, well-trained and slender individuals.
  高电压：心室肥厚（任何导联）。左束支传导阻滞（V5、V6、I、aVL 导联）。右束支传导阻滞（V1-V3 导联）。年轻、训练有素及体型瘦长者的正常变异。
• Low voltage: Normal variant. Misplaced leads. Cardiomyopathy. Chronic obstructive pulmonary disease. Perimyocarditis. Hypothyreosis (typically accompanied by bradycardia). Pneumothorax. Extensive myocardial infarction. Obesity. Pericardial effusion. Pleural effusion. Amyloidosis.
  低电压：正常变异。导联放置错误。心肌病。慢性阻塞性肺疾病。心包心肌炎。甲状腺功能减退（通常伴心动过缓）。气胸。广泛性心肌梗死。肥胖。心包积液。胸腔积液。淀粉样变性。
• Pathological Q-waves: Myocardial infarction. Left-sided pneumothorax. Dextrocardia. Perimyocarditis. Cardiomyopathy. Amyloidosis. Bundle branch blocks. Anterior fascicular block. Pre-excitation. Ventricular hypertrophy. Acute cor pulmonale. Myxoma.
  病理性 Q 波：心肌梗死。左侧气胸。右位心。心包心肌炎。心肌病。淀粉样变性。束支传导阻滞。左前分支阻滞。预激综合征。心室肥厚。急性肺心病。黏液瘤。
• Fragmented QRS complexes indicate myocardial scarring (mostly due to infarction).
  碎裂 QRS 波群提示心肌瘢痕形成（多由心肌梗死导致）
• Abnormal R-wave progression: Myocardial infarction. Right ventricular hypertrophy (reversed R-wave progression). Left ventricular hypertrophy (amplified R-wave progression). Cardiomyopathy. Chronic cor pulmonale. Left bundle branch block. Pre-excitation.
  R 波递增异常：心肌梗死。右心室肥厚（反向 R 波递增）。左心室肥厚（增强型 R 波递增）。心肌病。慢性肺源性心脏病。左束支传导阻滞。预激综合征。
• Dominant R-wave in V1/V2: Misplaced chest electrodes. Normal variant. Situs inversus. Posterolateral infarction/ischemia (if the patient experiences chest discomfort). Right ventricular hypertrophy. Hypertrophic cardiomyopathy. Right bundle branch block. Pre-excitation.
  V1/V2 导联 R 波优势：胸导联电极错位。正常变异。内脏反位。后侧壁心肌梗死/缺血（如患者出现胸痛症状）。右心室肥厚。肥厚型心肌病。右束支传导阻滞。预激综合征。
• Right axis deviation: Normal in newborns. Right ventricular hypertrophy. Acute cor pulmonale (pulmonary embolism). Chronic cor pulmonale (COPD, pulmonary hypertension, pulmonary valve stenosis). Lateral ventricular infarction. Pre-excitation. Switched arm electrodes (negative P and QRS-T in lead I). Situs inversus. Left posterior fascicular block is diagnosed when the axis is between 90° and 180° with rS complex in I and aVL as well as qR complex in III and aVF (with QRS duration <0.12 seconds), provided that other causes of right axis deviation have been excluded.
  电轴右偏：新生儿属正常现象。右心室肥厚。急性肺心病（肺栓塞）。慢性肺心病（COPD、肺动脉高压、肺动脉瓣狭窄）。侧壁心室梗死。预激综合征。肢体导联电极反接（I 导联 P 波和 QRS-T 波倒置）。内脏反位。左后分支阻滞的诊断标准为电轴 90°至 180°之间，I 和 aVL 导联呈 rS 波群，III 和 aVF 导联呈 qR 波群（QRS 时限<0.12 秒），且已排除其他导致电轴右偏的原因。
• Left axis deviation: Left bundle branch block. Left ventricular hypertrophy. Inferior infarction. Pre-excitation. Left anterior fascicular block is diagnosed if the axis is between -45° and 90° with qR-complex in aVL and QRS duration is 0,12 s, provided that other causes of left axis deviation have been excluded.
  电轴左偏：左束支传导阻滞。左心室肥厚。下壁梗死。预激综合征。左前分支阻滞的诊断标准为电轴-45°至 90°之间，aVL 导联呈 qR 波群且 QRS 时限 0.12 秒，且已排除其他导致电轴左偏的原因。
• Extreme axis deviation: Rarely seen. Probably misplaced electrodes. If the rhythm is wide QRS complex tachycardia, then the cause is probably ventricular tachycardia.
  电轴极度偏移：罕见。可能为电极放置错误。若伴宽 QRS 波心动过速，则病因可能为室性心动过速。

4. ST segment  4. ST 段

Common findings  常见表现

• Benign ST segment elevation is very common in the population, particularly in the precordial leads (V2–V6). Up to 90% (in some age ranges) of healthy men and women display concave ST-segment elevations in V2–V6 (this is called male/female pattern). ST-segment elevations which are not benign nor due to ischemia are rather common (listed below).
  良性 ST 段抬高在人群中非常常见，尤其是心前导联（V2-V6）。高达 90%（某些年龄段）的健康男性和女性在 V2-V6 导联显示凹面向上的 ST 段抬高（称为男性/女性模式）。非良性也非缺血性原因导致的 ST 段抬高相当常见（如下所列）。
• ST-segment depression is uncommon among healthy individuals. ST-segment depression is particularly suspicious in the chest leads. Guidelines recommend that <0.5 mm ST-segment depression be accepted in all leads.
  ST 段压低在健康人群中并不常见。胸导联出现 ST 段压低尤其值得怀疑。指南建议所有导联可接受<0.5 mm 的 ST 段压低。
• Causes of ST-segment elevation: Ischemia. ST segment elevation myocardial infarction (STEMI). Prinzmetal’s angina (coronary vasospasm). Male/female pattern. Early repolarization. Perimyocarditis. Left bundle branch block. Nonspecific intraventricular conduction disturbance. Left ventricular hypertrophy. Brugada syndrome. Takotsubo cardiomyopathy. Hyperkalemia. Post cardioversion. Pulmonary embolism. Pre-excitation. Aortic dissection affecting the coronary arteries. Left ventricular aneurysm.
  ST 段抬高的病因：缺血。ST 段抬高型心肌梗死（STEMI）。变异型心绞痛（冠状动脉痉挛）。男性/女性模式。早期复极。心包心肌炎。左束支传导阻滞。非特异性室内传导障碍。左心室肥厚。Brugada 综合征。应激性心肌病。高钾血症。心脏复律后。肺栓塞。预激综合征。累及冠状动脉的主动脉夹层。左心室室壁瘤。
• Causes of ST-segment depression: Ischemia. Non-ST segment elevation myocardial infarction (NSTEMI/NSTE-AKS). Physiological ST-segment depression. Hyperventilation. Hypokalemia. High sympathetic tone. Digoxin. Left bundle branch block. Right bundle branch block. Pre-excitation. Left ventricular hypertrophy. Right ventricular hypertrophy. Heart failure. Tachycardia.
  ST 段压低的病因：缺血。非 ST 段抬高型心肌梗死（NSTEMI/NSTE-AKS）。生理性 ST 段压低。过度换气。低钾血症。交感神经张力过高。地高辛作用。左束支传导阻滞。右束支传导阻滞。预激综合征。左心室肥厚。右心室肥厚。心力衰竭。心动过速。
• Causes of waves/deflections in the J point (J wave syndromes): Brugada syndrome. Early repolarization.
  J 点波/偏转的病因（J 波综合征）：Brugada 综合征。早期复极。

5. T-wave  5. T 波

Common findings  常见表现

• Normal variants: An isolated (single) T-wave inversion is accepted in lead V1 and lead III. In some instances the T-wave inversions from childhood may persist in V1–V3(V4), which is called persistent juvenile T-wave pattern. Rarely, all T-waves remain inverted, which is called global idiopathic T-wave inversion (V1–V6).
  正常变异：单独的 T 波倒置在 V1 导联和 III 导联是可接受的。某些情况下，儿童期出现的 T 波倒置可能持续存在于 V1-V3（V4）导联，称为持续性幼年型 T 波模式。极少数情况下，所有 T 波均保持倒置，称为全局特发性 T 波倒置（V1-V6）。
• T-wave inversion without simultaneous ST-segment deviation: This is not a sign of ongoing ischemia, but may be post-ischemic. One type of post-ischemic T-wave inversion is especially acute, namely Wellen’s syndrome (characterized by deep T-wave inversions in V1–V6 in patients with recent episodes of chest pain). Cerebrovascular insult (bleeding). Pulmonary embolism. Perimyocarditis (after normalization of the ST-segment elevation, T-waves become inverted in perimyocarditis). Cardiomyopathy.
  不伴 ST 段偏移的 T 波倒置：这不是急性缺血的征象，但可能是缺血后改变。其中一种缺血后 T 波倒置表现尤为典型，即 Wellen 综合征（表现为近期胸痛患者 V1-V6 导联深倒 T 波）。脑血管意外（出血）。肺栓塞。心包心肌炎（ST 段抬高恢复正常后出现 T 波倒置）。心肌病。
• T-wave inversion with simultaneous ST-segment deviation: acute (ongoing) myocardial ischemia.
  伴随 ST 段偏移的 T 波倒置：提示急性（进行性）心肌缺血。
• High T-waves: Normal variant. Early repolarization. Hyperkalemia. Left ventricular hypertrophy. Left bundle branch block. Occasionally perimyocarditis. High (hyperacute) T-waves may be seen in the very early phase of STEMI.
  高耸 T 波：正常变异。早期复极。高钾血症。左心室肥厚。左束支传导阻滞。偶见于心包心肌炎。ST 段抬高型心肌梗死超急性期可见高尖（超急性）T 波。

6. QTc interval and U wave
6. QTc 间期与 U 波

Common findings  常见表现

• Acquired QT prolongation: antiarrhythmic drugs (procainamide, disopyramide, amiodarone, sotalol), psychiatric medications (tricyclic antidepressants, SSRI, lithium, etc); antibiotics (macrolides, quinolones, atovaquone, chloroquine, amantadine, foscarnet, atazanavir); hypokalemia, hypocalcemia, hypomagnesemia; cerebrovascular insult (bleeding); myocardial ischemia; cardiomyopathy; bradycardia; hypothyroidism; hypothermia. A complete list of drugs causing QT prolongation can be found here.
  获得性 QT 间期延长：抗心律失常药物（普鲁卡因胺、丙吡胺、胺碘酮、索他洛尔）；精神科药物（三环类抗抑郁药、SSRI、锂盐等）；抗生素（大环内酯类、喹诺酮类、阿托伐醌、氯喹、金刚烷胺、膦甲酸、阿扎那韦）；低钾血症、低钙血症、低镁血症；脑血管意外（出血）；心肌缺血；心肌病；心动过缓；甲状腺功能减退；低温环境。完整致 QT 间期延长药物列表可查阅此处。
• Congenital QT prolongation: genetic disease of which there are approximately 15 variants.
  先天性 QT 间期延长：遗传性疾病，约存在 15 种亚型。
• Short QTc syndrome (≤ 0,32 s): caused by hypercalcemia and digoxin treatment. May cause malignant ventricular arrhythmia.
  短 QTc 综合征（≤0.32 秒）：由高钙血症及地高辛治疗引起，可能诱发恶性室性心律失常。
• Negative U-wave: high specificity for heart disease (including ischemia).
  负向 U 波：对心脏疾病（包括缺血）具有高度特异性。

7. Compare with earlier ECG
7. 与既往心电图对比

It is fundamental to compare the current ECG with previous recordings. All changes are of interest and may indicate pathology.
将当前心电图与既往记录进行对比至关重要。所有变化都具有临床意义，可能提示病理改变。

8. ECG and the clinical context
8. 心电图与临床背景

ECG changes should be put into a clinical context. For example, ST-segment elevations are common in the population and should not raise suspicion of myocardial ischemia if the patient does not have symptoms suggestive of ischemia.
心电图改变需结合临床背景解读。例如，ST 段抬高在人群中较为常见，若患者无缺血相关症状，则不应轻易怀疑心肌缺血。