You’ve just gotten comfortable with the probe. You can find the apical position. You’ve learned to trace the endocardium. Simpson’s biplane method, by the book. You press “measure.” The screen shows: EF = 68%.
You’re satisfied. Except the patient’s real EF is 52%.
What went wrong?
Welcome to the World of the Foreshortened LV
The most common technical error in echocardiography: apical foreshortening. You see the “apex,” but it’s not the real apex. The probe is slightly shifted or tilted, and instead of the true apex, you’re imaging a cross-section at the mid-segment level.
The result: the ventricle on screen looks shorter and rounder than it really is. When tracing with Simpson’s method, both systolic and diastolic volumes are underestimated, but the systolic volume less so. EF is overestimated — sometimes by 10–15%. You report “preserved function,” but the patient has moderate systolic dysfunction.
What Does a Proper Apical Position Look Like?
Three signs of the true apex:
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The apex is centered at the top of the screen. If the apex drifts to one side or the LV looks “flattened,” you’re in the wrong spot. The true apex should look like a cone, not a hemisphere.
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Maximum LV length. Try moving the probe slightly along the intercostal space and compare LV length in diastole. The position where the ventricle is longest is the correct one. If moving the probe 1 cm increases the length, you’re not there yet.
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The MV opens symmetrically. In the 4-chamber view, both mitral valve leaflets should open relatively symmetrically. If the image is oblique, you’ve probably shifted off-axis.
A Practical Self-Check
When you think you’ve found the apical position, do this:
Measure the LV length from the mitral annulus to the apex at end-diastole. Then slowly move the probe 1–1.5 cm laterally (toward the axillary line). If the length increases, the previous position was foreshortened.
This takes 20 seconds. Keep the position where the ventricle is longer.
Why Doesn’t Anyone Talk About This?
Because the machine doesn’t warn you. You see clean Simpson’s curves, a neat volume cone, a nice EF number. No flags, no warnings. The machine honestly calculated what you showed it.
Instructors often miss this in the early stages of training, especially when you have a good window and the image looks “normal.” That’s why this error lives unnoticed in someone’s practice for years.
Key Takeaway
Simpson’s EF is not an “objective number.” It is only as accurate as your position.
The habit of looking for maximum LV length before tracing takes 30 seconds, but those seconds are what turn an approximate estimate into a reliable measurement.
If a patient’s EF is “unexpectedly good” despite the clinical picture, the first thing to check: is there foreshortening?