Arterial supply of the heart
posterior aortic sinus ‐‐> left coronary artery (LCA)
anterior aortic sinus ‐‐> right coronary artery (RCA)
LCA ‐‐> LAD + circumflex
RCA ‐‐> posterior descending
RCA supplies SA node in 60%, AV node in 90%, Right ventricle (RV) and Inferior wall
Venous drainage of the heart;
coronary sinus drains into the right atrium
| Description | ECG leads with changes | Artery occluded |
|---|---|---|
| Inferior | II, III, aVF | RCA |
| Anteroapical | V3 and V4 | Distal LAD |
| Anteroseptal | V1 and V2 | LAD |
| Anterolateral | I, aVL, V5 and V6 | Circumflex artery |
| Extensive anterior | I, aVL, V2-V6 | Proximal LCA |
| True posterior | Tall R in V1 | RCA |
Untreated, the mortality associated with an inferior wall MI (IWMI) is less than 5% at 1 year after the event. With an anterior wall MI (AWMI), mortality untreated is closer to 30% to 40%. Thus, AWMI has the worst prognosis.
Look for the unique symptoms that may be associated with IWMI:
bradycardia, diarrhea and lightheadness due to irritation of the left branch of the vagus nerve (that runs closely between the inferior wall and esophagus)
Posterior MI is caused by occlusion of LCX or RCA, characterized by ST depression in leads V1-V3
If associated with ST elevation in leads 1 & aVL, LCX is blocked.
If associated with ST depression in leads 1 & aVL, RCA is blocked.