Noninvasive assessment of pressure gradients across iliac artery stenoses: duplex and catheter correlative study

The present study investigates prospectively the validity and accuracy of the simplified Bernoulli equation in the duplex-derived determination of pressure gradients across iliac artery stenoses in patients with occlusive artery disease. In 28 patients (age range, 38 to 76 years; mean, 53 years) with short iliac artery stenoses, we obtained both duplex scan stenotic jet velocity and catheter pressure measurements. Mean and maximum pressure gradients were determined by both methods, as was the peak-to-peak catheter gradient. The correlation between the duplex-determined and nonsimultaneously measured catheter mean pressure gradients was r = 0.77 (standard error of the estimate [SEE] = 5 mm Hg), that between the duplex-derived and catheter-determined maximum pressure gradients was r = 0.80 (SEE = 10 mm Hg), and that between maximum duplex-determined and peak-to-peak catheter gradient was r = 0.76 (SEE = 12 mm Hg). The peak-to-peak catheter gradient was significantly lower than the maximum duplex-derived gradient (46 versus 53 mm Hg, P < 0.05). Duplex-determined mean pressure gradient decreased from 15 +/- 6 to 3 +/- 1 mm Hg after balloon angioplasty of the iliac stenoses. Duplex scan can be used to predict pressure gradients across short iliac artery stenoses, provided that errors caused by angle malcompensation are prevented.