Interpretation

Sinus tachycardia with first-degree AV block and unifocal PVCs.

Lead I and Lead aVF are both more positive (point up). 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 not present in any of the leads.

ST segment depression and inverted T waves are not present in any of the leads.

Pathological Q waves are present in Lead III and Lead aVF indicating an inferior wall MI and tissue necrosis of undetermined age.

Clinical Significance
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With the presence of pathological Q waves on the 12-Lead, the suspicion would be the patient had an acute MI one week ago when he experienced left anterior chest pain. His clinical presentation now indicates heart failure with the presence of persistent crackles, an S3 gallop, jugular vein distention, and 1+ pitting edema of the ankles.

An inferior wall MI is caused by an occlusion of the right coronary artery. If the patient is left dominant, it is the circumflex artery. (Dominance refers to the artery that is supplying the posterior descending artery.)

In reviewing the 12-Lead, the wider P waves in Lead II indicate left atrial enlargement.

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.