Foreshortening occurs when the apical imaging plane does not pass through the true ventricular apex. The ultrasound beam cuts across the ventricle, making the apex appear rounded or blunted and shortening the measured long axis.
This is not a cosmetic problem. Foreshortening changes chamber shape, reduces measured volume, can alter calculated ejection fraction, and may hide apical pathology.
How a false apex is created
The true apex is not always located directly beneath the first palpable apical impulse or the first window that produces a recognizable four-chamber image. When the transducer is positioned too medially, too laterally, too superiorly, or at an incorrect angle, the imaging plane may intersect the LV before reaching its true tip.
Visual clues
- The apex appears rounded rather than tapered.
- The LV looks short and broad.
- The apical segments appear unusually thick.
- The LV long axis changes substantially with small probe movement.
- The apical two- and four-chamber lengths differ more than expected.
- The papillary muscles or trabeculations appear too close to the apex.
- The traced contour requires an artificial point to create an apex.
Why foreshortening changes volume and EF
Biplane Simpson volume divides the ventricle into a stack of discs based on the traced contour and long-axis length. A shortened long axis produces smaller disc volumes. End-diastolic and end-systolic volumes are both affected, and the resulting EF may be falsely increased, decreased, or deceptively unchanged depending on how each frame is distorted.
Foreshortening also affects longitudinal strain because apical tracking segments are shortened and the region of interest may not represent the true myocardial path.
Acquisition strategy
1. Start with anatomy, not the probe marker
Use the mitral annulus, ventricular long axis, septum, lateral wall, and apex to judge the plane. The view should maximize LV length without distorting chamber orientation.
2. Search for the longest LV
Slide the transducer laterally, medially, inferiorly, or superiorly while maintaining contact. Rock and angle through adjacent windows. The longest, most tapered LV is usually closer to the true apex.
3. Separate translation from rotation
Translation moves the transducer to a different acoustic window. Rotation changes the imaging plane through the same window. A false apex often requires translation, not merely rotation.
4. Optimize sector and depth
Use enough depth to include the entire apex and atria, then narrow the sector to improve frame rate. Avoid cutting off the apical epicardium.
5. Compare apical views
The four-, two-, and three-chamber views should share a similar maximal LV length. Major differences suggest inconsistent windows or foreshortening.
Apical four-chamber quality markers
- Interventricular septum is appropriately oriented and not excessively oblique.
- LV apex is clearly visualized and tapered.
- Mitral annulus is not artificially tilted.
- Both ventricles are included without sacrificing the true LV apex.
- The RV-focused view is acquired separately when RV dimensions are required.
Apical two-chamber pitfalls
The apical two-chamber view should display the anterior and inferior walls without the RV. Overrotation may bring the RV or LVOT into view. Underrotation may retain septal or lateral segments. The true apex should remain fixed while the plane rotates around the LV long axis.
Apical three-chamber pitfalls
The apical long-axis view should display the LVOT, aortic valve, and mitral valve while preserving the true apex. It is easy to move off the apex while searching for the LVOT. Reconfirm LV length before Doppler and tracing.
Contrast and alternate windows
When two or more contiguous endocardial segments are not adequately visualized and accurate LV volume or EF is clinically important, ultrasound-enhancing agents may improve border definition. Contrast cannot correct a foreshortened plane; it only clarifies the border in the plane acquired.
When standard windows are limited, use modified apical, more lateral, or subcostal windows and document the method.
Digital zoom, post-processing, and contour editing cannot recreate anatomy that was not included in the original imaging plane.
Consequences beyond EF
- Apical aneurysm or thrombus may be missed.
- Apical hypertrophic cardiomyopathy may be underestimated.
- Regional wall-motion abnormalities may be mislocalized.
- LV length used in area-length calculations becomes inaccurate.
- LA volume may also be affected when the atrial long axis is not maximized.
Before accepting an apical tracing
| Apex | Tapered and fully visualized, not rounded or truncated |
|---|---|
| Length | Maximized and similar between apical views |
| Contour | Follows compacted myocardium without papillary muscles or trabeculation |
| Frame | True end-diastolic and end-systolic frames selected |
| Image quality | Use contrast or alternate windows when borders are inadequate |
Knowledge check
1. What is the most important correction for a rounded false apex?
Answer: Move the transducer to a different window and search for the longest, tapered LV.
2. Can contrast correct foreshortening?
Answer: No. It improves border definition but cannot restore anatomy excluded from the plane.
3. Why may foreshortening falsely increase EF?
Answer: It can disproportionately reduce measured end-diastolic volume and alter the relationship between EDV and ESV.