Chronic Venous Insufficiency: Ambulatory Venous Pressure & Compression (2D)

Valve & Pump Pathophysiology

Valve competence 40%

Calf-pump activity (cadence) 100 spm

Standing time per cycle 8 s

Compression Therapy

Stocking grade (ankle) 0 mmHg

Live Readout

Ambulatory pressure

0 mmHg

Phase

Standing

Post-walk trough

— mmHg

Edema index

How it works

Standing venous pressure is a hydrostatic column: P = ρ·g·h, calibrated here so a ~1.15 m ankle-to-heart column of blood (ρ≈1060 kg/m³) gives the textbook resting value of ≈90 mmHg. A graduated compression stocking subtracts directly from that column by raising interstitial pressure, and — because it is graduated, highest at the ankle — the model's compression slider sets the ankle value the whole leg gradient scales from.

Each footfall fires a calf-muscle-pump ejection that drives pressure toward a floor, but only a fraction proportional to valve competence "sticks" — the rest refluxes straight back down through incompetent valves (ambulatory venous hypertension, the real pathophysiology of CVI). Between footfalls, pressure continuously re-fills toward the hydrostatic ceiling at a rate that itself rises with valve incompetence, since failed valves let blood re-pool even while walking:

ceiling  = P_hydro − P_compression(ankle)
refill   = k0 + (1 − valveComp) · kReflux          // per-second
eject(i) = (P − floor) · 0.30 · valveComp · pumpAssist   // per footfall
pumpAssist = 1 + 0.3 · (compression / 40)          // stiffer stocking, stronger pump

Healthy valves + walking — AVP falls from ~90 mmHg toward <30 mmHg within a few steps and stays low.
Incompetent valves — AVP barely falls with walking and stays in the 60–90 mmHg pathologic range even mid-exercise — venous hypertension persists despite activity.
Compression — lowers the ceiling directly and boosts pump ejection efficiency, the two real mechanisms graduated compression therapy uses.

Superficial vein / valve Incompetent valve / reflux Compression stocking Interstitial edema