 Vascular graft burst pressure

Vascular graft burst pressure is the internal-to-external pressure difference at which a vascular graft fails by rupture in a specified pressurization test. It is a destructive strength measurement. The vascular graft burst-test conditions, including mounting, surrounding pressure, pressure ramp and failure location, are needed to interpret the reported number. Leakage at a connector and rupture of the graft wall are different observed events.

An elementary thin-walled pressure vessel calculation explains the role of geometry. Cut a cylindrical tube of radius $r$, wall thickness $h$ and length $L$ along its axis. The resultant pressure force on a half-cylinder is $2rL\Delta p$, balanced by two cut walls carrying $2hL{\sigma }_{\theta }$. Thus the hoop stress isIf a stipulated wall failure stress is $1\mathrm{MPa}$, $h=0.20\mathrm{mm}$ and $r=2.0\mathrm{mm}$, this model predictsThis is an illustrative membrane-force balance, not a measured graft specification. It assumes a thin, uniform wall and ignores local defects, changing radius, nonlinear material response and attachment effects. The measured rupture pressure need not equal this estimate.

The primary engineered-bovine-artery study measured rupture strength as well as static and dynamic mechanical response within 24 hours of harvesting vessels. Those were distinct endpoints, rather than interchangeable definitions of graft quality.^[ref]

A graft that survives a particular pressure test has not thereby demonstrated a specified graft patency or repeated-loading lifetime. Conversely, a burst-pressure comparison alone does not measure vascular graft compliance mismatch. A useful report separates the observed failure event, its pressure difference and the test conditions from predictions about subsequent biological performance.