Anteroseptal infarction on ECG

كيف يظهر في التخطيط

The area of interest is leads V1–V3, sometimes involving V4. In the acute phase, hyperacute broad T waves are possible followed by or nearly simultaneous with ST-segment elevation; the sequence is variable, and hyperacute T waves may be absent or short-lived — ST elevation often becomes the first noticeable sign. Pathological Q/QS waves may appear in the acute phase or later, reflect changes in excitation spread, and cannot by themselves determine transmurality of necrosis.

An important feature: QS in V1 is sometimes normal, whereas QS in V2 and especially in V1–V2 requires checking electrode position, comparison with previous ECGs, and assessment of other signs. A pathological Q wave in these leads is considered to be a change compared with the baseline ECG, appearance of notching, increase in width or depth, and most importantly — combination with ST-T elevation/evolution and clinical picture.

In isolated anteroseptal involvement, a Q wave in I, aVL, V5–V6 is usually absent — this distinguishes it from extensive anterior or anterolateral infarction.

مخططات حقيقية: 8 أمثلة

مخطط قلب من قاعدة البيانات المفتوحة PTB-XL (Wagner P. et al., Scientific Data, 2020; PhysioNet)، ترخيص CC BY 4.0. الرسم - منصة WhiteCoat Pro.

الآلية

The interventricular septum and the adjacent anterior wall of the LV are supplied by septal perforating branches and proximal anterior septal branches of the LAD. Occlusion of this LAD segment causes ischemia and necrosis of the septum, which on ECG is reflected by ST elevation and Q-wave formation specifically in the leads electrically facing the septum — V1–V3. Since the septum contains the proximal portions of the right and left bundle branches, extensive septal necrosis may cause intraventricular conduction disturbances (right bundle branch block, rarely bifascicular blocks).

الأسباب

• Atherothrombotic occlusion or critical stenosis of the proximal/mid LAD involving septal branches
• Atherosclerotic plaque rupture with thrombosis (the most common mechanism of STEMI)
• Coronary spasm in the LAD territory (variant angina)
• تسلخ الشريان التاجي (بما في ذلك التسلخ العفوي، SCAD)
• Embolism into the LAD (rare)
• Iatrogenic occlusion of a septal branch during coronary interventions

التشخيص التفريقي

• Normal variant QS in V1: QS in V1 is sometimes normal, without ST-T evolution, without clinical picture, stable on previous ECGs; QS in V2 and wider requires checking electrode position and ruling out pathology
• Left bundle branch block: wide QRS, typical morphology in V1 and V5–V6, masks and mimics the Q wave; infarction is assessed by Sgarbossa criteria (modified — Smith)
• Brugada syndrome (type 1 pattern): coved elevation of the J point/ST usually ≥2 mm in at least one of leads V1–V2 recorded in the standard (4th intercostal space) or high (2nd–3rd intercostal space) position, followed by a negative T wave; requires clinical-electrocardiographic assessment — an isolated Brugada-like pattern without the appropriate context does not equal a clinical syndrome
• Hypertrophic cardiomyopathy with septal hypertrophy: deep narrow Q waves combined with tall R waves, without ST-T evolution
• Myocarditis: diffuse ST-T changes without strict relation to a single artery territory, often together with changes in inferior and lateral leads
• Early repolarization: ST elevation with J-point notch, concave, without reciprocal depression and without Q-wave formation

الأهمية السريرية والتكتيكات

New ST elevation in V1–V3(V4) in two contiguous leads with clinical evidence of ischemia is STEMI requiring emergency reperfusion (primary PCI within the recommended window, and if unavailable — fibrinolysis according to current criteria and time frames). One should actively look for extension to the lateral wall (I, aVL, V5–V6) and the at-risk territory of the right ventricle/conduction system, and consider the appearance of new bundle branch blocks as a marker of extensive involvement.

ST elevation in aVR with diffuse ST depression indicates high ischemic risk and possible left main/multivessel disease, but does not allow an anatomical diagnosis; an immediate invasive strategy is indicated under the appropriate very high-risk criteria. In the absence of ST elevation but with suspected ACS (e.g., a pattern resembling Wellens syndrome in precordial leads), the approach is different — an early invasive strategy for NSTE-ACS, not emergency PCI "as STEMI".

Prior anteroseptal infarction (persistent Q without acute evolution) requires assessment of LV ejection fraction and LV thrombus, risk of anterior wall/apex aneurysm, and prescription of antithrombotic and other secondary prevention as indicated. Anticoagulation is prescribed for documented LV thrombus, atrial fibrillation, or another established indication; antiarrhythmic drugs — for a specific arrhythmia and taking risk into account; in reduced EF, indications for ICD implantation are assessed for primary prevention of sudden death after optimal medical therapy and in accordance with recommended waiting periods.

الأخطاء الشائعة أثناء قراءة تخطيط القلب

• Mistaking a physiological QS in V1 for a pathological Q without assessing evolution and clinical picture; forgetting that QS in V2 and wider requires checking
• Interpreting a pathological Q as a sign of acute STEMI by itself — without new ST elevation or occlusion equivalent and clinical picture, it only indicates possible necrosis/scarring
• Not comparing the current ECG with previous ones — missing the new appearance of Q or ST elevation
• Ignoring left bundle branch block as a possible masking factor of infarction
• Not assessing lead contiguity — the diagnosis of STEMI requires ST elevation in two or more contiguous leads, not in one random lead
• Forgetting gender and age differences in ST elevation thresholds in V2–V3 when interpreting borderline values

الأسئلة الشائعة

المصطلحات ذات الصلة

المزيد في قسم «نقص تروية واحباط عضلة القلب»

القسم بأكمله

المصادر

• Goldberger's Clinical Electrocardiography، الطبعة الحالية
• AHA/ACCF/HRS Recommendations for the Standardization and Interpretation of the Electrocardiogram, 2009
• Surawicz B., Knilans T. Chou's Electrocardiography in Clinical Practice
• أورلوف ف.ن. دليل تخطيط القلب الكهربائي

مادة تعليمية لطلاب كليات الطب والأطباء. لا تحل محل التوصيات السريرية والفحص الطبي؛ يُفسر تخطيط القلب دائماً جنباً إلى جنبกับการحالة السريرية.