Which is used for calculation of ejection fraction?
**Core Concept**
Ejection fraction (EF) is a critical measure of left ventricular function, calculated as the percentage of blood ejected from the left ventricle during systole. It is a key parameter in assessing cardiac performance and diagnosing conditions such as heart failure.
**Why the Correct Answer is Right**
To calculate ejection fraction, the formula used is:
EF = (End-diastolic volume - End-systolic volume) / End-diastolic volume
The end-diastolic volume (EDV) is the volume of blood in the left ventricle at the end of diastole, while the end-systolic volume (ESV) is the volume of blood left in the ventricle at the end of systole. By dividing the difference between EDV and ESV by EDV, we obtain the ejection fraction, which represents the proportion of the ventricle's volume that is ejected with each beat.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not involve the calculation of ejection fraction. Instead, it is a measure of cardiac output, which is the volume of blood pumped by the heart per minute.
**Option B:** This option is incorrect because it refers to the calculation of cardiac output, not ejection fraction. Cardiac output is calculated as the product of heart rate and stroke volume.
**Option C:** This option is incorrect because it is a measure of left ventricular pressure, not ejection fraction. Left ventricular pressure is an important parameter in assessing cardiac function, but it is not directly related to ejection fraction.
**Clinical Pearl / High-Yield Fact**
When interpreting ejection fraction values, it's essential to consider the context and the patient's clinical presentation. A normal ejection fraction is typically considered to be above 55-60%, but this can vary depending on the population being studied.
**Correct Answer: C. The formula used for calculation of ejection fraction is: (End-diastolic volume - End-systolic volume) / End-diastolic volume.**