Right Posterior Descending Artery (RPDA) Territory
The Right Posterior Descending Artery (RPDA) supplies the posterior one-third of the interventricular septum via septal perforator branches, and contributes to the inferior wall of the left ventricle in right-dominant circulation. 1
Primary Anatomical Territory
The RPDA has a well-defined anatomical distribution:
The RPDA runs in the posterior interventricular groove and supplies septal perforator branches that perfuse the posterior third of the interventricular septum 1, 2
In right-dominant circulation (approximately 90% of individuals), the RPDA arises from the right coronary artery and contributes to blood supply of the inferior wall of the left ventricle 1, 3
The posterior descending septal perforators originating from the PDA are the specific vessels that deliver blood to the septal tissue 1
Relationship to Coronary Dominance
Understanding coronary dominance is critical for interpreting RPDA territory:
Right dominance (90% of cases): The PDA and posterolateral artery (PLA) both arise from the RCA, making the RPDA the primary supplier to the inferior septum and inferior left ventricular wall 1, 3
Co-dominant circulation: The RCA supplies the PDA while the circumflex supplies the PLA, meaning both vessels contribute to inferior wall perfusion 1
Left dominance (10% of cases): The PDA arises from the left circumflex artery rather than the RCA, so there would be no "RPDA" in these patients 1
Clinical Significance
The RPDA territory has important clinical implications:
Occlusion of the RPDA can result in inferior wall myocardial infarction and posterior septal involvement, which may lead to ventricular septal rupture (VSR) occurring in 1-2% of all myocardial infarctions with 54% mortality in the first week without surgery 2
The posterior septal perforators from the PDA are targets for alcohol septal ablation in hypertrophic cardiomyopathy, where 1-3 cc of ethanol creates controlled septal infarction 2
Anatomic variants exist where the PDA may be duplicated or arise from anomalous sources (such as continuation of LAD around the apex), which can complicate surgical planning 4, 5, 6
Important Caveats
The extent of RPDA territory varies based on the length of the vessel - a short PDA supplies less septal territory, while a long PDA may extend further toward the apex 7
The posterior right diagonal artery (PRDA), when present in 15% of right-dominant systems, may also perfuse the inferior posterior septum, particularly when the PDA is short 7
Always verify coronary dominance before attributing specific territory to the RPDA, as anatomic variants can significantly alter the expected perfusion patterns 8, 5, 6