ECG Library

Save

All ECG 7

Enlarge 
Source: Learn the Heart
Which of the following does the above ECG represent?

Posterior wall infarction frequently occurs with an inferior wall MI caused by occlusion of a large, anatomically-dominant right coronary artery.

On the ECG, posterior wall ECG changes are the opposite of those seen with other myocardial segments. Instead of ST segment elevation, a posterior MI is characterized by ST depression in lead V1 and frequently V2, and the R wave is large in these leads. Turn the ECG upside down and you can visualize ST segment elevation in V1 and a large Q wave. For more detail, click on the Posterior MI ECG Review link below.

Note that the causes of an R wave being larger than the S wave in lead V1 include a posterior MI, right bundle branch block, Wolff-Parkinson-White syndrome type A, right ventricular hypertrophy, ventricular tachycardia with a right bundle branch block pattern and isolated posterior wall hypertrophy (with Duchenne's muscular dystrophy).

Related: Inferior MI ECG ReviewPosterior MI ECG ReviewLeft Atrial Enlargement ECG Review