How the model works
Short-lived loading experiments use shared pressure, flow and reflex rules.
Squat, stand from squat, handgrip, passive leg raise and Valsalva are alternative provocations. Selecting one clears the other maneuver rather than stacking contradictory postures or strain phases.
The model displays representative endpoints and a constructed Valsalva time course. It is not measuring autonomic function, predicting fluid responsiveness from filling pressure, or simulating symptoms and exercise tolerance.
| Maneuver | Selected response |
|---|---|
| Squat | Raises venous return and SVR; reduces dynamic LVOT obstruction. Fixed MR/AR may gain upstream load. |
| Stand from squat | Immediate fall in preload/pressure before full reflex recovery; intact sinus reflex can accelerate. Dynamic obstruction/prolapse can worsen. |
| Handgrip | Raises systemic afterload with modest rate response; fixed MR/AR or VSD burden can increase, while HOCM obstruction can decrease. |
| Passive leg raise | Transient redistribution of venous volume. More flow recruitment is allowed when underfilled; congestion or pump/valve limitation favors pressure rise over output gain. |
Phase I applies transmitted thoracic pressure and an arterial rise. Phase II reduces venous return/filling; later phase II adds reflex resistance and rate response. Phase III releases pressure with an arterial fall. Phase IV restores return with an overshoot and recovery.
A congested LV-failure phenotype can show an illustrative flat-top response. Depletion, dynamic obstruction and RV disease change preload sensitivity; neurogenic/distributive states and vasoactive drugs modify reflexes. Beta blockade, digoxin and atropine alter rate-response terms. The phase graph is generated from the same response function as the selected static phase.
Valsalva adds an external thoracic pressure term to measured cavity pressures while reducing effective filling. PV volume excludes that external offset. The venous-return line in the study is a relative response factor, not an independently measured absolute caval flow.
Mouseover links each time segment to its pressure, SVR, HR and venous-return explanation. The maneuver itself is not treated as a management-error warning; other contraindicated therapies remain separately assessed.
