Endovenous Laser Ablation: Bioheat & Thermal Damage Lab (2D)

Laser Delivery

Linear energy density (LEED) 70 J/cm

Fiber pullback speed 1.2 mm/s

Great saphenous vein diameter 6.0 mm

Live Readout

Peak wall temp

37.0 °C

Fiber position

70.0 mm

Coagulated length

0.0 mm (0%)

Elapsed time

0.0 s

Predicted outcome

— run the fiber to find out

How it works

A 71-node finite-difference grid spans the 70 mm treated segment of vein. As the fiber withdraws at the chosen speed v, the linear energy density you set (LEED, in J/cm) fixes the instantaneous laser power through P = (LEED/10)·v — the same energy per millimetre gets delivered whether the fiber moves fast or slow, but power (and therefore instantaneous heating rate) scales with speed. Each grid node's temperature obeys a discretized Pennes bioheat equation:

ρc·∂T/∂t = k·∂²T/∂x² − h(d)·(T−37°C) + Q(x,t)

where the conduction term (k = 0.5 W/m·K) spreads heat along the wall, the perfusion-equivalent sink h(d) grows with vein diameter (a wider lumen carries away more heat before the fiber compresses and treats it), and Q is the laser source, deposited as a Gaussian around the current fiber position. Every node also integrates the classic Arrhenius thermal-damage model:

Ω(x) = ∫ A·exp(−Eₐ / R·T(x,t)) dt,  A = 3.1×10⁹⁸ s⁻¹, Eₐ = 6.28×10⁵ J/mol

A node is considered irreversibly coagulated once Ω ≥ 1 — the point at which protein denaturation becomes effectively certain. Too little LEED and the damage front never closes the full segment (patent vein, treatment failure); too much and the peak wall temperature runs well past the ~100 °C steam-bubble threshold. The middle pane plots T(x) live; the bottom pane shows the coagulation front eating into the vein length as Ω crosses 1.

Laser fiber / heat source Temperature profile T(x) Coagulated (Ω ≥ 1)