Hemodynamic assessment of aortic stenosis in the catheterization laboratory accurate determination of the transvalvular gradient. A commercially available double-lumen pigtail catheter can be used to obtain this gradient via a single arterial puncture. The catheter has several advantages over other methods used to measure the gradient in aortic stenosis, but it has not been critically evaluated. In order to assess the performance of this catheter compared to the traditional standard of separate catheters above and across the aortic valve, we studied 10 patients with aortic stenosis using both catheter systems. Aortic valve areas ranged from 0.34 cm2 to 1.1 cm2. Linear regression analysis confirmed excellent correlation between the two methods in measurement of the mean transvalvular gradient (r = 0.98) and calculation of the aortic valve area (r = 0.99) using the Gorlin formula. We conclude that the double-lumen pigtail catheter provides accurate data in the hemodynamic evaluation of aortic stenosis.