EFFECT OF CATHETER POSITIONING ON THE VARIABILITY OF MEASURED GRADIENT IN AORTIC-STENOSIS

The purpose of this study was to quantify the variation in measured ao rtic valve gradient and calculated aortic valve area when different te chniques of cardiac catheterization were utilized. Hemodynamic assessm ent of aortic stenosis severity requires an accurately determined pres sure gradient. In aortic stenosis, the presence of intraventricular pr essure gradients and downstream pressure recovery within the aorta mea ns that a range of aortic valve gradients could be measured in a given patient depending upon catheter position and measurement technique. T o quantify the degree of variation in measured gradient and calculated aortic valve area, we generated transvalvular gradients by nine diffe rent techniques in 15 patients (11 men, 4 women; 29-86 years old). Pat ients were divided into those with severe aortic stenosis (aortic valv e area less than or equal to 0.6 cm(2), n = 6) and those with moderate ly severe aortic stenosis (aortic valve area 0.61-0.90 cm(2), n = 9). Considerable variation in measured gradient and calculated aortic valv e area was observed. The maximum variation in gradient was similar in severe and moderately severe aortic stenosis groups (33 mm Hg. vs. 32 mm Hg., p = NS). However, the variation in gradient as a percent of ma ximum gradient was greater (P<0.05) in the moderately severe aortic st enosis group. The maximum variation in calculated aortic valve area wa s 0.1 cm(2) in the severe group and 0.3 cm(2) in the moderately severe group (P<0.01). An intraventricular gradient, present in 13 of 15 (87 %) patients, was partially responsible for the variation in pressure g radient measurement and calculated aortic valve area. We conclude that in patients with valvular aortic stenosis, catheterization technique has an important impact on the hemodynamic assessment of aortic stenos is severity. This is particularly true in patients with moderately sev ere aortic stenosis where any variation tends to represent a larger pe rcentage of the total gradient. (c) 1993 Wiley-Liss, Inc.