Final answer:
The most commonly used method for calculating ejection fraction via M-mode echocardiography is Simpson's method of discs. Ejection fraction is a measurement of the blood volume ejected from the heart during each beat, usually ranging from 55-70 percent.
Step-by-step explanation:
The method most often used for calculating ejection fraction by M-mode echocardiography is B. Simpson's method of discs. Ejection fraction (EF) is an important cardiac parameter that represents the volume of blood ejected from the left ventricle with each heartbeat. It is calculated by dividing the stroke volume (SV) by the end-diastolic volume (EDV) of the heart. EF is customarily expressed as a percentage. Normal ejection fractions range approximately from 55-70 percent, with an average around 58 percent. It's a crucial measure in diagnosing and monitoring patients with heart conditions.