LV 17-Segment Model: Echo Views and Coronary Territories
Interactive 17-segment bull's-eye with segment names and numbers, the apical and short-axis views in which each segment is seen, typical LAD, LCx and RCA territories, and wall-motion scoring.
The LV 17-segment model provides a standard method for describing the location of left ventricular myocardium across echocardiography, cardiac MRI, CT and nuclear perfusion imaging. This reference identifies every LV segment, the echocardiographic views in which it is seen, and its typical coronary artery territory. For routine echocardiographic wall-motion scoring the 16-segment model is generally preferred, because segment 17 — the apical cap — cannot be reliably assessed for wall thickening or endocardial excursion.
16-Segment versus 17-Segment LV Models
| Model | Segments | Preferred use |
|---|---|---|
| 16-segment | 1 – 16 | Routine echocardiographic regional wall-motion assessment, WMSI and regional strain |
| 17-segment | 1 – 17 | Myocardial perfusion imaging and cross-modality comparison with CMR, CT, SPECT and PET |
Interactive 17-Segment Bull's-Eye
Click or tap any segment to view its name, number, level, typical coronary territory and the echocardiographic views in which it is best seen. Segments are colour-coded by typical coronary artery territory.
LV Segments by Apical Echocardiographic View
Each standard apical view images two opposing walls at basal and mid level, plus two of the four apical-level segments. The three views together cover all 16 wall segments. Note that the septum seen in the apical four-chamber view is the inferoseptum, and its opposing free wall is the anterolateral wall — not the inferolateral wall.
| Apical view | Wall | Basal | Mid | Apical level |
|---|---|---|---|---|
| Apical 4-chamber | Inferoseptal | 3 | 9 | 14 — apical septal |
| Apical 4-chamber | Anterolateral | 6 | 12 | 16 — apical lateral |
| Apical 2-chamber | Anterior | 1 | 7 | 13 — apical anterior |
| Apical 2-chamber | Inferior | 4 | 10 | 15 — apical inferior |
| Apical 3-chamber (LAX) | Anteroseptal | 2 | 8 | 14 — apical septal |
| Apical 3-chamber (LAX) | Inferolateral | 5 | 11 | 16 — apical lateral |
LV Segments in Short-Axis Views
Parasternal short-axis imaging divides the ventricle into three levels of equal length. The basal and mid levels each contain six segments; the apical level contains four; the apical cap is a single segment with no cavity.
| Short-axis level | Segments | Names |
|---|---|---|
| Basal (mitral leaflet level) | 1 – 6 | Anterior, anteroseptal, inferoseptal, inferior, inferolateral, anterolateral |
| Mid (papillary muscle level) | 7 – 12 | Anterior, anteroseptal, inferoseptal, inferior, inferolateral, anterolateral |
| Apical (beyond papillary muscles) | 13 – 16 | Anterior, septal, inferior, lateral |
| Apical cap | 17 | Apex — myocardium beyond the end of the LV cavity |
Typical Coronary Artery Territories
These assignments represent common population patterns rather than fixed anatomical rules. Individual segments — particularly the inferior, inferoseptal, inferolateral and apical segments — may receive blood supply from a different artery depending on coronary dominance, vessel length and branch anatomy.
| # | Segment | Level | Typical territory | Common variation |
|---|---|---|---|---|
| 1 | Basal anterior | Basal | LAD | — |
| 2 | Basal anteroseptal | Basal | LAD | — |
| 3 | Basal inferoseptal | Basal | RCA | LAD (septal perforators) |
| 4 | Basal inferior | Basal | RCA | LCx in left dominance |
| 5 | Basal inferolateral | Basal | LCx | RCA in strong right dominance |
| 6 | Basal anterolateral | Basal | LCx | — |
| 7 | Mid anterior | Mid | LAD | — |
| 8 | Mid anteroseptal | Mid | LAD | — |
| 9 | Mid inferoseptal | Mid | RCA | LAD (septal perforators) |
| 10 | Mid inferior | Mid | RCA | LCx in left dominance |
| 11 | Mid inferolateral | Mid | LCx | RCA in strong right dominance |
| 12 | Mid anterolateral | Mid | LCx | — |
| 13 | Apical anterior | Apical | LAD | — |
| 14 | Apical septal | Apical | LAD | RCA (posterior descending) |
| 15 | Apical inferior | Apical | RCA | LAD if wrap-around apex |
| 16 | Apical lateral | Apical | LCx | LAD |
| 17 | Apex (apical cap) | Apex | LAD | Any of the three vessels |
Wall-Motion Scoring and WMSI
Several scoring conventions exist. The five-point system used by the 2020 ASE stress echocardiography guideline is shown below. Some laboratories use a four-point system and describe aneurysmal remodelling separately, in line with the 2015 chamber quantification document, which recommends characterising an aneurysm morphologically rather than assigning it a distinct score.
| Score | Wall motion | Systolic thickening | Description |
|---|---|---|---|
| 1 | Normal or hyperkinetic | > 50% | Normal endocardial inward motion and systolic wall thickening |
| 2 | Hypokinetic | < 40% | Reduced endocardial inward motion and wall thickening |
| 3 | Severely hypokinetic or akinetic | < 10% | Markedly reduced or absent inward motion and thickening |
| 4 | Dyskinetic | — | Outward systolic motion away from the LV centre (paradoxical bulging) |
| 5 | Aneurysmal | — | Diastolic deformation with systolic dyskinesis |
Common Interpretation Pitfalls
| Pitfall | Implication |
|---|---|
| Scoring excursion without thickening | Assess both systolic wall thickening and inward endocardial excursion. Thickening is the more specific marker of contractile function |
| Tethering and translation | Reduced motion with preserved thickening often reflects tethering to an adjacent abnormal segment or whole-heart translation, rather than infarction of that segment |
| Basal segment attachment | Basal septal and basal inferior excursion can appear reduced because of attachment to the cardiac fibrous skeleton — a normal finding |
| Conduction and postoperative septal motion | LBBB, RV pacing and post-cardiac-surgery septal motion mimic regional dysfunction. Judge the septum on thickening rather than motion in these settings |
| Apical foreshortening | Truncates the apical segments and distorts both regional assessment and volume measurement. See LV volumes and ejection fraction |
| Poor endocardial definition | Use an ultrasound-enhancing agent when two or more contiguous endocardial segments cannot be adequately visualised |
| Scoring segment 17 | Including the apical cap in WMSI is a common error and biases the index. Exclude it from wall-motion and regional strain assessment |
Frequently Asked Questions
What is the difference between the 16- and 17-segment models?
Both divide the left ventricle into basal, mid and apical levels using the same nomenclature. The 17-segment model adds the apical cap — segment 17 — and is intended for myocardial perfusion imaging and comparison with CMR, CT, SPECT and PET. The 16-segment model omits the apical cap and is preferred for routine echocardiographic wall-motion assessment, because the apical cap has no cavity and its thickening and excursion cannot be reliably scored.
Which LV segments are seen in the apical four-chamber view?
The apical four-chamber view images the inferoseptal wall — basal inferoseptal (3) and mid inferoseptal (9) — and the opposing anterolateral wall — basal anterolateral (6) and mid anterolateral (12) — together with the apical septal (14) and apical lateral (16) segments. The anteroseptal and inferolateral walls are imaged in the apical long-axis view, not the four-chamber view.
How is the wall motion score index calculated?
Each segment is scored, then WMSI is the sum of the segment scores divided by the number of segments assessed. A normal WMSI is 1.0. The apical cap (segment 17) is not normally included, and any segment that cannot be adequately visualised should be excluded from both the numerator and the denominator rather than assumed normal.
Which coronary artery supplies the LV apex?
The apex is most commonly supplied by the left anterior descending artery, particularly where it wraps around the apex. However, apical supply is genuinely variable and can come from the circumflex or the right coronary artery depending on vessel length and dominance, so apical wall-motion abnormalities localise culprit vessels less reliably than basal or mid-level abnormalities.
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