Read One Beat from Filling to Output
A cardiac cycle links passive filling, valve closure, ejection, and the volume pumped each minute.
Cardiac Cycle and Output is the central idea in this question pattern. Identify the condition in the stem before applying the method below.
Follow filling and sounds
Most ventricular filling is passive during joint diastole. The first heart sound (“lub”) follows closure of the atrioventricular valves at the start of ventricular systole. Ejection into the aorta occurs during systole.
Calculate output
For EDV 120 mL, ESV 50 mL and 70 beats/min, output is 70×70=4,900 mL/min or 4.9 L/min.
Heart rate, filling and cardiac output
Cardiac output equals heart rate × stroke volume. At very high heart rates, shortened diastole may reduce ventricular filling and stroke volume, so output need not rise proportionally with rate.
Calculate stroke volume and cardiac output
convert mL/min to L/min by dividing by 1,000. For 120 mL, 50 mL and 70 beats/min, output is 4.9 L/min.
OlympIQ exam lens
- ✓Joint diastole → passive filling.
- ✓Lub → AV valve closure/start of ventricular systole.
- ✓SV = EDV−ESV.
- ✓CO = SV×heart rate.
Do not use end-systolic volume as the ejected volume; subtract it from EDV first.
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