Coronary Artery Territories on 2D Echocardiography
The left anterior descending artery (LAD) supplies the anterior wall, anteroseptum, and apex; the left circumflex artery (LCX) supplies the lateral wall; and the right coronary artery (RCA) supplies the inferior wall and inferoseptum in most patients. 1
LAD Territory
The LAD territory encompasses the most extensive myocardial region visible on 2D echo:
- Basal segments: Basal anterior and basal anteroseptal 1
- Mid segments: Mid anterior and mid anteroseptal 1
- Apical segments: Apical anterior, apical septal, and the apical cap 1
Important caveat: The LAD frequently extends beyond these traditionally assigned segments. Research demonstrates that LAD infarcts commonly involve the mid-anterolateral, apical lateral, and apical inferior walls, with 100% specificity for LAD occlusion only in the basal anteroseptal, mid-anterior, mid-anteroseptal, and apical anterior segments. 2
LCX Territory
The LCX supplies the lateral wall of the left ventricle:
- Basal segments: Basal anterolateral and basal inferolateral (also called basal posterior) 1
- Mid segments: Mid anterolateral and mid inferolateral (also called mid posterior) 1
- Apical segments: Apical lateral 1
Critical distinction: The basal anterolateral wall shows 98% specificity for LCX occlusion, and the combination of hyperenhancement in both anterolateral and inferolateral walls is 100% specific for LCX occlusion. 2 In dominant or codominant LCX systems, the territory extends to include inferior wall segments. 2
RCA Territory
The RCA primarily supplies the inferior and inferoseptal regions:
- Basal segments: Basal inferior and basal inferoseptal 1
- Mid segments: Mid inferior and mid inferoseptal 1
- Apical segments: Apical inferior 1
Anatomical variability: The RCA supplies the posterior descending artery (PDA) in approximately 90% of people (right-dominant circulation), which runs in the posterior interventricular groove and provides septal perforator branches. 3 The posterolateral segmental artery represents the distal RCA continuation after the PDA origin in right-dominant hearts. 3
Clinical Pitfalls
No single segment is 100% specific for RCA or LCX occlusion alone, unlike the LAD where four segments show complete specificity. 2 This reflects significant anatomical variability in coronary dominance patterns and collateral circulation.
Segment overlap occurs frequently: Research shows 23% of infarcted segments are discordant with empirically assigned coronary distributions, emphasizing the importance of analyzing adjacent segments together rather than in isolation. 2
Echocardiographic visualization limitations: While the LM and LAD segments are completely visualized in 96-98% of patients, the proximal Cx is seen in only 88% and the RCA segments in only 40-54% of patients with standard transthoracic windows. 4 Multiple imaging planes and transducer positions are required for optimal visualization of all coronary segments. 1, 3