What 12 lead EKG leads are indicative of a right coronary artery (RCA) ST elevation myocardial infarction (STMI)?

Answer 1

For a right coronary artery (RCA) ST-elevation myocardial infarction (STEMI), the classic ECG pattern shows ST elevation in the inferior leads: Lead II, Lead III and Lead aVF. These leads view the inferior wall of the left ventricle which is supplied by the RCA. When ST elevation in lead lll is higher than it is in lead ll, this helps narrow the problem down to the RCA and a RV infarct. This is confirmed by greater than or equal to 1 mm ST elevation in the right-sided lead V4R. In general, the main changes to look for are a T-wave inversion (the infarction disrupts repolarization and alters the direction of the electrical current) and ST-segment elevation(corresponds with this injury).

Answer 2

Some additional information-- If the right side of the heart does not receive blood supply, the left side will try to compensate by becoming hyperactive. Typically we see a left axis deviation in lead activity (L.A.D), signifying more electrical current moving on the left side of the heart. Therefore lead I would give a positive ST wave. And the AVF would display a negative inversed wave.

During the ST wave, ventricles are fully depolarized and isoelectric. Repolarization begins immediately after this segment at the T wave. During a STEMI, tissue dies and normal electrical pathway for ventricular depolarization is disrupted. An alternate longer pathway may be taken resulting in an overall higher net voltage measured by the leads. This alternate pathway is called the "injury current"

Answer 3

Leads II, III, and aVF are indicative RCA involvement STMI.