All ECG 26
- Normal sinus rhythm
- Posterior myocardial infarction
The posterior wall demonstrates ECG changes the opposite of other myocardial segments due to the location, thus instead of ST segment elevation, a posterior myocardial infarction is characterized by ST depression in lead V1 and frequently V2. The R wave is large in lead V1. Turn the ECG upside down and you will see ST segment elevation in V1 and a large Q wave which are normal findings of a myocardial infarction. For a detalied review, click the Posterior MI ECG Review button below.
Note that the causes of a R wave being larger than the S wave in lead V1 include a posterior myocardial infarction, right bundle branch block, WPW Type A, right ventricular hypertrophy, ventricular tachycardia with a right bundle branch block pattern and isolated posterior wall hypertrophy (can occur with Duchenne's muscular dystrophy).
Related Topic Reviews: Posterior MI ECG Review