From the Guidelines
To evaluate left ventricular systolic function from a transthoracic echocardiogram (TTE) parasternal short-axis (PSAX) view at the level of the papillary muscles, you should assess wall motion and thickening of all visible myocardial segments, and consider using midwall fractional shortening (FSmw) as it better reflects myocardial contractile status in patients with LV hypertrophy 1. When evaluating LV systolic function, it's essential to consider the limitations of traditional measurements such as ejection fraction (EF) and fractional shortening (FS), as they may overestimate LV systolic performance in patients with LV hypertrophy 1.
Key Steps in Evaluation
- Visually estimate the overall contractility, looking for symmetric contraction of the LV walls with appropriate thickening during systole
- Measure the fractional shortening by comparing the internal dimensions during systole and diastole, with normal values showing approximately 25-45% reduction in cavity size during contraction
- Assess for regional wall motion abnormalities by dividing the short-axis view into segments (anterior, anterolateral, inferolateral, inferior, inferoseptal, and anteroseptal) and scoring each segment's motion (normal, hypokinetic, akinetic, or dyskinetic)
- Evaluate papillary muscle motion, as they should contract toward the center of the cavity during systole
Additional Considerations
- For more precise quantification, consider using this view for speckle tracking echocardiography to assess circumferential strain, which provides information about myocardial deformation in the circumferential direction
- Midwall fractional shortening (FSmw) can be calculated using the formula: FSmw = {(LVIDd + IVSd/2 + PWd/2)² - (LVIDs + Hs/2)²}/(LVIDd + IVSd/2 + PWd/2), where Hs is the systolic thickness of the shell 1
- Stress-corrected FSmw can be calculated to eliminate the effects of LV afterload on FSmw, using the formula: cESS = {[SBP × (LVIDs/2)²] × [1 + (LVIDs/2 + LV²PWs)²/(LVIDs/2 + LV²PWs/2)²]}/{(LVIDs/2 + LV²PWs)² - (LVIDs/2)²}, where SBP represents systolic blood pressure 1