Posterior Descending Artery

ramus interventricularis posterior

The posterior descending artery runs in the posterior interventricular groove, supplying the inferior ventricular septum, posterior left ventricular wall, and the AV node. In right-dominant coronary anatomy (85% of individuals) it arises from the right coronary artery; in left-dominant anatomy (10-15%) from the left circumflex; and in co-dominant systems from both. Coronary dominance is defined by which artery gives the PDA.

Region: Chest

Clinical Relevance

Clinical Notes

The PDA supplies the AV node in most individuals through the AV nodal artery, which is why RCA occlusion frequently produces AV block alongside inferior MI. PDA territory infarction affects the inferior left ventricle and the posterior septum, producing inferior Q waves and right ventricular involvement. In bypass surgery, the PDA is a target vessel for grafting in patients with right dominant anatomy and significant inferoposterior disease. Understanding dominance is essential when planning revascularisation and predicting infarct complications.

Pathology

Common Injuries & Conditions

Inferior MI with AV Block

Proximal RCA occlusion obstructs both the PDA territory and the AV nodal artery, producing inferior ST elevation MI complicated by first, second, or third degree heart block, which usually resolves with reperfusion and rarely requires permanent pacing unlike AV block in anterior MI.