Anatomical Position of the Right Coronary Artery (RCA)
No, the right coronary artery (RCA) is not anterolateral. The RCA is located in the right atrioventricular groove and has a posterior course.
Anatomical Course of the Right Coronary Artery
The right coronary artery (RCA) has a specific anatomical position and course that is well-defined in cardiac imaging guidelines:
- The RCA originates from the right coronary sinus (right anterior coronary sinus) 1
- It courses through the right atrioventricular groove 1
- The RCA has proximal, middle, and distal segments that follow this groove 1
- It typically continues beyond the crux of the heart to supply the posterior descending artery in right-dominant circulation 1
Visualization of RCA Segments
According to the American Heart Association guidelines, the RCA can be visualized in several specific views during echocardiography 1:
- Proximal RCA: Visualized in precordial short axis at level of aortic valve, precordial long axis (inferior tangential) of left ventricle, subcostal coronal projection of right ventricular outflow tract, and subcostal short axis at level of atrioventricular groove
- Middle RCA: Visualized in precordial long axis of left ventricle (inferior tangential), apical 4-chamber, subcostal left ventricular long axis, and subcostal short axis at level of atrioventricular groove
- Distal RCA: Visualized in apical 4-chamber (inferior) and subcostal atrial long axis (inferior)
Clinical Significance of RCA Position
The posterior course of the RCA has important clinical implications, particularly in myocardial infarction:
- When the RCA is occluded, the spatial vector of the ST segment is directed inferiorly and to the right 1
- This results in ST-segment elevation in leads II, III, and aVF (with greater elevation in lead III than in lead II) 1, 2
- Reciprocal ST-segment depression is often seen in leads I and aVL 1, 2
- Proximal RCA occlusion may cause right ventricular infarction, resulting in ST-segment elevation in right precordial leads (V3R and V4R) 1, 2
Anomalous RCA Courses
While the normal RCA follows the right atrioventricular groove in a posterior direction, anomalous courses have been reported:
- In rare cases, the RCA may originate from the left anterior descending artery 3, 4, 5
- Extremely rare cases of meandering retrosternal course have been reported 6
- Single coronary artery anomalies where the RCA originates from the LAD are very rare (approximately 40 cases in 15,000 coronary angiograms) 3
Importance in Cardiac Imaging
Understanding the normal posterior course of the RCA is essential for:
- Proper interpretation of coronary angiography and echocardiography 1
- Accurate diagnosis of coronary artery anomalies 1
- Correct interpretation of ECG findings in inferior wall myocardial infarction 1, 2
- Planning interventions such as coronary artery bypass grafting 5
The RCA's normal course in the right atrioventricular groove with a posterior direction is a fundamental anatomical concept in cardiovascular medicine, and recognizing deviations from this normal anatomy is crucial for accurate diagnosis and treatment of coronary artery disease.