How to get an Ejection Fraction from the LVSAX view.

Step 1: easure the left ventricular diameter in end-diastole.M Do not measure the based upon the image end-diastole. Position the frame where the mechanical end-diastole occur on the ECG

The optimal view for measuring the left ventricular diastolic area is the left ventricular short axis view from the mid transgastric acoustic window. This view has been shown to be predictive of the LVEDV. The area is converted into left ventricular end-diastolic volume. The formula used is the Tiecholz formula which is based upon the spherical volume of the heart multiplied by a correction factor. Since the volume of a sphere is the cube of the radius, and the left ventricle is almost a sphere, a correction factor to account for the non spherical qualities of the left ventricle yields a surprisingly accurate result.

RWMA, either close or distant, may cause the volume analysis to be incorrect. If the endocardial boarder is poorly seen, then the area of the left ventricular cavity may be inaccurate. Failing hearts (i.e. cardiomyopathy) tend to be more spherical than normal hearts so the spherical formula may be more accurate.