History and Clinical Correlation

78-year-old male with a long history of COPD was admitted two days ago with pneumonia. He calls out complaining of a sudden onset of chest pain. He is cool, clammy, anxious, and restless. An S4 gallop and fine bibasilar crackles are auscultated.

Systematic Steps in Interpretation
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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 rhythm with normal intervals.

Lead I is positive and Lead aVF is equiphasic. Normal axis.

Axis is important to look at with an acute MI. A conduction defect, such as fascicular blocks will cause an axis shift, and failure to recognize the block could be lethal.

ST segment elevation is present in V3-V4. Anterior wall MI.

Anterior occurs in conjunction with septal wall MI. ST segment elevation in V1 and V2. Anteroseptal MI.

Anterior occurs in conjunction with lateral wall. ST segment elevation in I and aVL. T wave inversion is present in V5-6. Lateral extension.

The ST segment depression in Lead III is reciprocal and not concerning.

There are no pathological Q waves.

The inverted P waves in V1 and V2 are indicative of probable right atrial (or biatrial) enlargement. The patient has a long history of COPD and pulmonary hypertension.

Clinical Significance
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Anterior wall MI rarely occurs alone. When lateral or septal involvement with the anterior wall, complications may include severe left ventricular dysfunction resulting in heart failure, cardiogenic shock, and a high mortality. The clinical presentation indicates early shock as evidenced by cool, clammy, and restlessness. The S4 gallop occurs due to resistance to filling and is auscultated with an acute MI. The fine bibasilar crackles are indicative of heart failure.

An anteroseptal wall MI with lateral extension is caused by an occlusion of the left main or proximal left anterior descending artery.

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.