Examples

Make sure to select the data file from the installer folder and click on the record button. On not doing so, you might get an error prompt. This will not affect your program but it simply will not record the data in the .xls sheet.

Error dialog box

As shown in the video, change the values of the parameters by referring to the user guide. As we are showing the LV failure, in the Dilated HF tab, the ESPVR 1 is selected at the LV ESPVR hypothesis and the RV ESPVR hypothesis is kept at linear (You can find the complete guide to the HF selections in the User guide: Reference Set-Up). Also, if you don’t find any of the parameters on the simulator then those are already set for you (like E-lv and E+lv)

Please refer the CVS Simulator User Guide for the all the values of the parameters and a detailed description on the features of this simulator.

conditions
Normal Conditions

As you can see above, the simulator is running at the default values, i.e. the pump is off and there are no heart diseases or conditions. As you progress further you’ll see the changes in the PV loops with varying conditions, and hence preload and afterload

Pressure-Volume Relationship

PV loops provide us with an understanding of the fundamental mechanics of the cardiac contraction, effect of ventricular contraction with  and without the pump functions (coupled with the vascular system)

The information is as such attainable from the time graphs, some data is only detected by the PV loops, like:

  1. The total energy imparted during ventricular contraction, by looking at the external work (EW) or Stroke Work (SW).
  2. ESPVR and EDPVR, which presents the mechanical property of the ventricles, are easy to represent in the PV Loop.
  3. Information about the ventriculoarterial interactions and myofilament interactions, change in the cardiac chamber, myocardial contractility can also be obtained through this PV relationship.

Heart Diseases

Heart Failure

heart failure
LV Failure: The left ventricular (LV) pressure (in red) reduces and there is a decrease in both, Aortic flow (in light blue) and the Atrioventricular flow (AoV flow – in grey), as compared to the normal conditions; The ESPVR 1 (LV failure) conditions are added as shown here
heart failure
Bi Ventricular Failure: Similar to LV Failure, there is also an increase in the Right ventricular (RV) pressure ( in yellow) and the pulmonary arterial pressure (in green).

These are two of the 4 HF conditions. There is a rightward shift of the PV loops due to the translocation of blood to the pulmonary circuit, resulting in an increase in the LV end-diastolic volume (EDV).

Valvular Disease

stenosis
Aortic Stenosis : Changes in the left ventricular (LV) pressure (in red) in response to increasing the Aortic valve value under stenosis. Increase in the pressure from ~120 mmHg to ~ 180mmHg. 

Stenosis prevents the valve from opening fully, resulting in an increased heart rate, an increase in the ventricular filling (ventricular hypertrophy) to keep up the cardiac output. Both, PVR slopes (systolic and diastolic) become stiffer – increase upward; there is a rightward shift of the PV loops with time. The LV pressure rises to overcome the pressure drop across the valve and maintain aortic pressure.

Vascular disease
Aortic Regurgitation : There is a decrease in the Aortic pressure ( in dark blue) and an increase in the backward flow (in light blue) as the valve regurgitation value is decreased. 

Regurgitation leads to a steeper ESPVR line, an increase in heart rate and an increase in ventricular filling pressure. There is a rightward shift of the PV loops with time. As this shift continues, the heart will undergo massive dilation.

See for yourself: Recreate other heart disorders. Which parameters are changed?

Left Ventricular Assist Device (LVAD)

adding the pump
LVF with constant pump speed: Increase in the LV and the Aortic pressure, while a decrease in the Aortic flow and AoV flow is seen as a result of increasing the pump speed and hence pump flow.

adding the pump
LVF with pump at ramp speed: Same as the constant speed, this allows us to see the similar changes in a gradual manner.

adding the pump
LVF with pulsatile pump speed: Increasing the speed leading to a reduced ESV and increased inotropy as seen in the PV loops ; change in the aortic pressure is seen as a result of increasing the pulsatile ratio; the phase shift of the rotor causes the changes in the HQ curves. Changing these three paramters simultaneously causes major changes at the LV & Aortic pressure, Aortic and pump flow, PV loops and HQ curves.

See for yourself: Check out the different LVAD modes with other HF modes. What happens when you increase the contractility and the afterload?