Measurement of Renal Artery Pressures by Catheterization in Patients with and without Renal Artery Stenosis

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Abstract
Pressures were successfully measured by catheterization in 13 out of 18 renal arteries with stenosis and in 15 out of 16 vessels without stenosis. The pressures were measured via a small-bore, radiopaque nylon catheter threaded through a curved polyethylene catheter whose tip was placed in the renal vessel. The position of the catheters was confirmed by injections of small volumes of angiographic dye and documented by spot films. Use of the small-bore catheter was necessary to avoid alteration of the measured pressure. Strict attention to technical details is mandatory in order to obtain satisfactory pressure recordings. In patients without angiographic evidence of stenosis, pressure in the renal arteries did not differ consistently from the aortic pressure. Differences of more than 15 mm Hg in the systolic pressure are probably abnormal. Abnormal systolic pressure gradients between the aorta and the renal artery were found in some patients with renal artery stenosis, but not in others. In the patients with gradients, good correlation was obtained between the gradient and the dimensions of the stenosis measured on the angiographic films and expressed as L s /(D s /D N ), 2 where L s is the length of the narrowing, and D s and D N are respectively the diameters of the lumen of the stenotic and nonstenotic parts of the vessel in a frontal projection. Our experience suggests that more preoperative pressure measurements by catheterization across renal artery stenosis and correlation relation with angiographic and renal function studies and with the results of operation are warranted.