Pearls of Knowledge: Acute Inferior Wall MI with Right Ventricular
Thursday, February 20, 2025
12-Lead ECG Interpretation: Acute Inferior Wall MI with Right Ventricular
Pearls of Knowledge © BrainyNurses.com
A lot of information can be gleaned from a 12-Lead ECG and using systematic steps will help to identify all the components. Considering the patient’s history and clinical presentation can provide some helpful clues as to what to look for, especially if you are more of a novice in 12-Lead interpretation. The focus for this 12-Lead interpretation is to look for evidence of ischemia, injury, or infarction.
History and Clinical Correlation
52-year-old male who presents to the ED via the EMS having chest pain. After the initial 12-Lead ECG, the paramedic gave nitroglycerin sublingually, and the blood pressure decreased to 80/40. He is pale, cool, and clammy.
Systematic Steps in Interpretation
Steps when chest pain is present.
• Identify the rhythm.
• Determine axis (Memory Hint: “Right together, Left apart” using leads I and aVF).
• Look for signs of an acute MI (ST segment elevation of 1 mm or more).
• Look for signs of ischemia (ST segment depression and symmetrically inverted T waves).
• Look for signs of myocardial necrosis (Q wave more than 1/3 the height of the R wave).
Using this guide, evaluate axis, the leads identified for the above changes, and the impression.
Interpretation
Sinus tachycardia with first degree AV block. The P waves are hard to find. In V3-V5, the T wave is identified, the next “bump” is a U wave, and the “bump” before the QRS is the P wave.
Looks like a normal axis but difficult to determine due to the distortion caused by the MI.
ST segment elevation is present in Leads II, III, and aVF. Inferior wall MI.
Inferior can occur in conjunction with lateral wall. There is no ST segment elevation in V5-V6, or in Lead I or aVL. The lateral wall is clean for infarction. The ST depression could represent ischemia.
Inferior can occur in conjunction with the right ventricular wall. The ST segment is higher in Lead III than Lead II. Probable, right ventricular.
ST segment is elevated in V1 and extends to V3. Elevation in V1 is predictive for right ventricular MI.
Pathological Q wave is present in Lead III and indicates necrosis.
Clinical Significance
Inferior wall MI with right ventricular involvement represents a large amount of muscle mass and a substantial increase in in-hospital morbidity and mortality. Complications can include cardiogenic shock; ventricular dysrhythmias; second-degree, type II AV block; and third-degree AV block. The administration of nitroglycerine followed by hypotension is classic for right ventricular infarction due to the reduction of preload because of vasodilation.
An inferior wall with right ventricular MI is caused by an occlusion of the proximal right coronary artery.
Summary
A systematic approach to 12-Lead ECG interpretation is essential in detecting changes and applying them to the clinical setting. Changes occur with numerous conditions including acute coronary syndrome, other pathological disorders, conduction disturbances, electrolyte and acid base imbalances, and with medications.
To enhance care provided for cardiac patients, check out Clinical Application and Interpretation of the 12-Lead ECG. It is on-line, on-demand, with voice-over-power-point, and a comprehensive review to use at the bedside.
The extensive handout is easy to follow and includes a composite reference sheet to use in the session and post on the clinical unit afterwards. In addition, “In My Pocket” cards are included as a ready reference tool.
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