Question

The cardiac output of a 70-year-old man at rest is 5L/min; mean HR is 85 bpm. Left ventricular end-diastolic volume (LVEDV) is estimated to average 82 ml. What is the mean ejection fraction?

Total peripheral resistance= mean arterial pressure/flow
Mean arterial pressure= (Systolic pressure) +2 {Diastolic pressure}/3
Cardiac output= Heart rate X Stroke Volume

Answer 1

The mean ejection fraction (EF) for a 70-year-old man with a cardiac output of 5L/min, a heart rate of 85 bpm, and a left ventricular end-diastolic volume (LVEDV) of 82 ml is approximately 71.7%, calculated by dividing stroke volume by LVEDV.

Step-by-step explanation:

The question pertains to determining the mean ejection fraction (EF) of a 70-year-old man whose cardiac output (CO) and left ventricular end-diastolic volume (LVEDV) are known. The ejection fraction is a measurement used in cardiology to assess how much blood the left ventricle pumps out with each contraction relative to its filled volume.

Using the provided data, the stroke volume (SV) can be calculated using the formula CO = HR x SV, which rearranges to SV = CO / HR. The EF can then be determined by dividing the SV by the LVEDV and expressing it as a percentage.

Calculations: Since CO = 5 L/min (5000 mL/min) and HR = 85 bpm, SV = 5000 mL/min / 85 bpm = 58.82 mL (rounded to two decimal places).

EF is then SV/LVEDV = 58.82 mL / 82 mL = 0.717 (or 71.7%).

Therefore, the mean ejection fraction for the individual is approximately 71.7%, which is within the normal range.