An objective comparison of four stress tests in the assessment of "at risk" femoro-distal grafts.

Femoro-distal vein grafts for limb salvage have a 30% failure rate at 6 months. Graft surveillance may enable the "at risk" grafts to be recognised and corrected, but there remains the need for a simple test to identify these patients. The ankle pressure response to exercise and reactive hyperaemia has been investigated prospectively in 40 "at risk" femoro-distal non-reversed grafts (median age 73 years, range 51-87 years, M/F = 33:7), defined as those with a resting ankle brachial index less than 0.9 or a drop of greater than 0.2 following a stress test. Four different stress tests have been assessed; active ankle plantar-dorsiflexion for 2 minutes (I), occlusive calf cuff 50 mmHg above systolic pressure for 2 minutes (II), treadmill exercise test for 1 minute, slope = 10%, at 3 km/hr (III) and 4 km/hr (IV). Ankle brachial indices (ABI's) were recorded before and immediately following each test and expressed as mean % drop +/- standard error of mean. Test I was only tolerated by 45% of patients whereas 55% and 50% could complete tests III and IV respectively. By contrast, 85% of patients could tolerate occlusive cuff hyperaemia (test II). Test I produced a significantly lower mean percentage drop in ABI when compared with each of the others (p less than 0.02, Mann U Whitney). There was an excellent correlation between test II and both the 3 km/hr (r = 0.77, p less than 0.001) and 4 km/hr (r = 0.84, p less than 0.001) exercise tests.(ABSTRACT TRUNCATED AT 250 WORDS)