A 60-year-old male presents with chest pain. Which ECG leads changes indicate the presence of an inferior wall myocardial infarction (MI)?

1. A

   V1, V2, V3, V4

2. B

   II, III, aVF

3. C

   I, aVL, V5, V6

4. D

   V7-V9

Appeared in: NORCET-7 Mains-2024

Explanation

Listen in Hindi

• Leads II, III, and aVF directly monitor the electrical activity of the inferior surface of the heart.
• ST-segment elevation or other ischemic changes in this specific lead group are diagnostic for an inferior wall myocardial infarction.
• This location of infarction is most commonly caused by an occlusion of the Right Coronary Artery (RCA).

Why Other Options Were Wrong

• Option A: Leads V1, V2, V3, and V4 view the anterior and septal walls of the heart.
• Option C: Leads I, aVL, V5, and V6 view the lateral wall of the left ventricle.
• Option D: Leads V7-V9 are posterior leads used to view the posterior wall of the heart.

Related Visual

Clinical Relevance

• Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain ECG lead interpretation for Myocardial Infarction location as background academic context rather than a clinical decision trigger.
• Rapid identification of the MI location via ECG is critical for nurses to anticipate potential complications. For example, inferior MIs (RCA involvement) are often associated with bradycardia and heart blocks, requiring close monitoring of heart rate and rhythm.
• Prompt recognition allows for faster activation of the cardiac catheterization lab for percutaneous coronary intervention (PCI), which is the primary treatment for ST-elevation MI (STEMI) to restore blood flow.
• What if? If the patient with an inferior MI also develops hypotension, bradycardia, and has clear lung sounds, the nurse should suspect right ventricular (RV) involvement. A right-sided ECG (placing lead V4 on the right side, V4R) should be performed. Nitrates would be contraindicated in this case as they can worsen hypotension.

How to Approach the Question

• First, identify the core of the question, which is asking to link a specific type of myocardial infarction (inferior wall) with its corresponding ECG leads.
• Recall the anatomical groupings of the 12 ECG leads and the specific region of the heart each group visualizes.
• Systematically evaluate the options provided:
• Option A (V1-V4) corresponds to the anterior/septal wall.
• Option B (II, III, aVF) corresponds to the inferior wall.
• Option C (I, aVL, V5, V6) corresponds to the lateral wall.

Concept Tested & Keywords

• Concept Tested: ECG lead interpretation for Myocardial Infarction location
• Stem keywords: chest pain, ECG leads, inferior wall myocardial infarction, MI
• Lead-in keywords: Which
• Clinical cues: Patient with chest pain, suggesting an acute cardiac event.
• Negative lead-in flag: false

Question ID

QJL4p-O9DfV_TqyP54fb41

Copy ID

Reference Book

E6 Medicine Harrison 22e Part 1 pp. 1913-1915, 1914-1916

E6 Medicine Davidson Principles Practice 24e p. 468-470