Coronary Vessels on the Right Side
The right side of the heart is primarily supplied by the right coronary artery (RCA) and its branches, which in most people (approximately 90%) demonstrates right dominance, meaning it supplies the inferior wall of the left ventricle through the posterior descending artery (PDA) and posterolateral branches. 1
Primary Right-Sided Coronary Vessels
Right Coronary Artery (RCA) Segments
The RCA originates from the right aortic sinus and courses through the right atrioventricular groove. According to standardized ACC/AHA definitions, the RCA system includes 1:
- Right coronary artery ostium - The origin including the first 3 mm
- Proximal, middle, and distal RCA segments - Running in the atrioventricular groove
- Right ventricular branches - Arising from the RCA to supply the right ventricular wall
Major Branches in Right Dominant Circulation (75.6% of cases)
In right-dominant systems, which represent the majority of the population, the RCA gives rise to 1, 2:
- Right posterior descending artery (PDA) - Runs in the posterior interventricular groove and supplies septal perforator branches
- Posterolateral segmental artery - The distal continuation of the RCA in the posterior atrioventricular groove after the PDA origin
- First, second, and third right posterolateral branches - Originating from the right posterior atrioventricular artery
- Posterior descending septal perforators - Vessels originating from the PDA
Anatomical Variations and Clinical Considerations
Coronary Dominance Patterns
The ACC/AHA guidelines define three mutually exclusive dominance patterns 1:
- Right dominance (most common): The PDA and posterolateral artery (PLA) arise from the RCA
- Left dominance: The PDA and PLA arise from the left circumflex artery
- Co-dominance: The RCA supplies the PDA while the circumflex supplies the PLA
Important Anatomical Details
The RCA caliber typically measures 3.42 ± 0.66 mm at the proximal segment and 2.9 ± 0.50 mm at the acute angle of the heart 3. The vessel terminates between the crux cordis and left margin in approximately 75.6% of specimens 3.
A critical anatomical variation occurs in approximately one-third of cases where a vessel arises before the crux and contributes to left ventricular supply - either as an aberrant acute marginal artery or as an early posterior descending artery crossing the diaphragmatic surface of the right ventricle 2. This variation is surgically significant for complete revascularization.
Conduction System Supply
The RCA supplies critical cardiac conduction structures in the majority of cases 4:
- Sinoatrial (SA) node: Supplied by the RCA in 60.6-73% of cases
- Atrioventricular (AV) node: Supplied by the RCA in 80% of cases
This explains why RCA occlusion can result in bradyarrhythmias and conduction disturbances, particularly when the vessel is infused with agents like acetylcholine during coronary functional testing 5.
Imaging Considerations
For echocardiographic visualization of the RCA, multiple views are required 6:
- Proximal segment: Precordial short axis at aortic valve level; precordial long axis (inferior tangential); subcostal coronal projection
- Middle segment: Precordial long axis (inferior tangential); apical 4-chamber; subcostal views at atrioventricular groove level
- Distal segment: Apical 4-chamber (inferior); subcostal atrial long axis (inferior)
- Posterior descending artery: Apical 4-chamber (inferior); subcostal atrial long axis; posterior interventricular groove views
Common pitfall: The majority of coronary veins course within 5 mm of a coronary artery, with the middle cardiac vein most often running near the RCA 7. This proximity is critical for interventional procedures and device placement.