Presets
Playback
Apparatus
Model checks
The science
What is modelled
The ventricle is a chamber whose stiffness (elastance) rises and falls with each beat. Blood enters through the inlet valve while the chamber is soft, the valve shuts as it stiffens, the outlet valve opens when the pressure exceeds the aorta and blood is ejected into an elastic artery that drains through the body resistance.
Equations
- Chamber
P = E(t) (V − V0), with E(t) between a passive and a peak value. - Valves as diodes:
Q = max(0, ΔP) / R. - Volume
dV/dt = Qin − Qout. - Windkessel
C dPao/dt = Qout − (Pao − Pv) / Rs.
Checks run in the page
- Stroke volume from the loop against integrated aortic flow.
- Mean pressure against venous pressure plus flow times resistance.
- Loop area (shoelace) against the integral of P dV.
- Diastolic decay time against R C.
Honest simplifications
A lumped, single-chamber educational model: fixed valve resistances, an idealised elastance curve, a constant venous pressure and no atrium or coronary flow. It is not diagnostic software.
What to try
- Press Raised afterload: the ventricle must develop more pressure and the stroke volume falls.
- Press Exercise to see a shorter beat, higher output and a narrower loop.
- Press Weak ventricle and watch the ejection fraction drop.