Coronary artery dominance and EKG changes

Hello, hello!

Coronary arterial dominance is defined by the vessel which gives rise to the posterior descending artery (PDA).

Mnemonic: PDA is the posterior descending and DOMINATING artery.

It is also known as the posterior interventricular artery as it runs in the posterior interventricular groove to the apex.

PDA supplies the posterior third of the interventricular septum, including the posterior and inferior wall of the left ventricle.

70 to 80% of the population is right heart dominant, that is, PDA originating from the right coronary artery (RCA).

5 to 10% of the population is left heart dominant, that is, PDA originating from the left circumflex artery (LCx).

If there is occlusion of RCA that gives off the PDA, EKG will show ST elevations in the inferior leads (II, III, and aVF) and reciprocal ST-segment depression in lateral leads (aVL and I).

If there is occlusion of LCx that gives off the PDA, EKG will show ST elevations in the inferior leads (II, III, and aVF) and also in the lateral leads (V5 and V6).

Fig. 1: Infero-postero-lateral STEMI in a patient with left circumflex occlusion with left dominant coronaries.

Update: Cardiac cath showing obstructed Lcx of the patient in Fig. 1. Pre- and post-intervention images.

Fig. 2

Fig. 3

Fig. 4

I will update this post with images of RCA dominant STEMI if I come across it.

That's all!

-IkaN