Coronary DominanceEdit

Coronary dominance is a term used in cardiac anatomy to describe which coronary artery gives rise to the posterior descending artery (PDA) and, by extension, supplies the majority of the posterior portion of the interventricular septum and parts of the inferior wall of the heart. The concept reflects how the arterial supply to the heart’s posterior regions is organized and has practical implications for how myocardial territory is affected by arterial occlusion and for planning surgical or catheter-based interventions. In most hearts, the dominance pattern is determined by the origin of the PDA, but variations exist that can influence clinical outcomes in coronary disease and during procedures.

The dominant circulation is defined by which coronary artery provides the PDA and often the posterior veins that drain the corresponding myocardial territory. The right coronary artery (RCA) is the usual source of the PDA in the majority of individuals, whereas in a substantial minority, the PDA arises from the left circumflex artery (LCx), a branch of the left coronary artery (LCA). In some hearts, the PDA receives supply from both the RCA and LCx, a situation referred to as co-dominance. The left coronary artery itself typically gives rise to the left anterior descending artery (LAD) and LCx, which together nourish much of the anterior wall and lateral/posterior aspects of the left ventricle, while the RCA tends to supply the right atrium and right ventricle and, in the dominant pattern, the posterior region.

Anatomy and terminology

Coronary arteries: The two main arterial systems arise from the aorta and include the right coronary artery and the left coronary artery. The right coronary artery commonly travels in the right atrioventricular groove, while the left coronary artery bifurcates into the left anterior descending artery and the left circumflex artery.
Posterior descending artery (PDA): The artery that most often supplies the inferior portion of the heart’s septum and ventricles. The PDA is a key marker of dominance and may originate from the right coronary artery (right-dominant circulation) or from the left circumflex artery (left-dominant circulation); in some hearts, it is supplied by branches from both systems (co-dominant circulation).
Dominance patterns:
- Right-dominant: PDA arises from the RCA.
- Left-dominant: PDA arises from the LCx.
- Co-dominant: PDA receives supply from both RCA and LCx via posterior branches.
The dominance pattern helps determine which myocardial territories are at risk during occlusion of a given vessel and can influence the clinical presentation of myocardial infarction and the strategy used in revascularization.

Prevalence and variants

Right-dominant circulation is the most common pattern, occurring in roughly two-thirds to three-quarters of individuals in many populations.
Left-dominant circulation accounts for a minority, typically around one-fifth or less, depending on the population studied.
Co-dominant circulation is a recognized minority pattern, in which both the RCA and LCx contribute to the PDA system.
The exact prevalence of each pattern can vary with ethnicity, age, and study methodology, but the overarching principle remains that dominance is a structural variant with important clinical implications rather than a rarity.

Clinical implications

Myocardial territory at risk: In a right-dominant heart, occlusion of the RCA can jeopardize the PDA and the inferior/posterior portions of the heart, whereas in a left-dominant heart, occlusion of the LCx may risk the same territories. Co-dominant patterns distribute risk differently, potentially involving both vascular systems.
Myocardial infarction patterns: The dominance pattern can influence which regions of the heart become ischemic during an acute coronary event and can modify electrocardiographic and hemodynamic findings.
Surgical and interventional planning: Knowledge of dominance is important in procedures such as coronary artery bypass grafting (CABG), percutaneous coronary intervention (PCI), or valve surgery, because the arterial origins and collateral supply affect graft targets, expected collateral flow, and potential complications.
AV nodal blood supply: The atrioventricular (AV) node is often supplied by branches of the RCA, especially in right-dominant hearts, which has implications for rhythm disturbances in the setting of RCA disease. In left-dominant hearts, the LCx may contribute more to nodal perfusion, altering risk profiles for conduction issues during ischemia.
Diagnostic imaging: Noninvasive imaging modalities, including computed tomography coronary angiography and invasive coronary angiography, commonly identify dominance by tracing the PDA’s origin. This information is routinely reported because it informs prognosis and treatment planning.

Development and embryology

Coronary dominance is established during cardiac development as the coronary arterial system forms from a network of sprouts that connect to the aorta and perfuse the myocardium. The pattern of connections and the persistence of certain channels determine which artery becomes the principal supplier of the PDA. While this is a normal anatomical variation, its recognition is essential for understanding individual differences in coronary circulation and for anticipating territory-specific risks in ischemic heart disease.

Variants and related concepts

Anomalous coronary arteries: Some individuals have unusual origins or courses of the coronary arteries, which can interact with dominance in ways that affect risk during procedures or in the setting of congenital heart disease.
Myocardial territory mapping: In surgical planning or detailed cardiology workups, clinicians may map perfusion territories to anticipate how disease in one vessel will affect muscle supplied by another, especially in cases of atypical dominance.
Comparison with other vascular patterns: While coronary dominance is most commonly described in terms of the PDA, the same principles of selective supply apply to other major branches and their contributions to ventricular and septal perfusion.