Pressure gradients

Abstract

To examine the validity of pressure gradient determination during the períormance of percutaneous transluminal coronary angioplasty in distal, acutely angulated coronary artery branches, the degree of intrinsic gradients in such branches, independent of any atherosclerotic narrowing, must first be determined. Measurement of such intrinsic pressure gradients was performed in 14 angiographically normal coronary artery branches (mean diameter, 2.4 ± 1.0 mm), which arose at an angle of 90° ± 9° from the parent vessel. All pressures were measured using conventional angioplasty hardware (8F guiding catheter, 0.014-inch steerable guidewire, and 2.5-mm balloon catheter). The mean pressure gradient in these 14 branches was 9 ± 11 mm Hg, as opposed to a mean gradient of only 1 ±2 mm Hg in the main bodies of the parent vessels (P<0.05). Administration of intracoronary nitroglycerin had no significant effect on measured gradients. Ten of 14 vessel branches (71%) had a baseline gradient below 10 mm Hg; the mean gradient in these 10 branches was only 4 ± 3 mm Hg. The remaining 4 branches (29%) had baseline gradients greater than 10 mm Hg; in none of these 4 branches was the gradient reduced below 10 mm Hg following nitroglycerin administration. No significant correlations were observed between baseline branch gradient and either branch diameter (r=-0.22) or angle of branch origin (r=-0.01). Thus, intrinsic pressure gradients in distal, angulated coronary artery branches are quite small in most instances, suggesting that measurement of translesional gradients should be reliable during coronary angioplasty in such vessels. However, the possibility of an elevated gradient intrinsic to the vessel branch itself must be considered when gradient measurements are discordant with clinical and angiographic results