Phasic pressure gradients across coronary and renal artery stenoses in humans

Fluid-filled catheter-transducer systems have been developed for assessment of phasic pressure gradients across arterial stenoses. The two catheters we have employed are 3 French and 2 French in diameter. After the catheters are flushed with carbon dioxide and filled with degassed saline solution to remove microbubbles of air, the catheters are attached to a low-volume displacement transducer. The frequency response of both catheter-transducer systems is adequate to record phasic arterial pressures. The catheters are very flexible and radioopaque, and the ability to monitor phasic pressure continuously at the tip during passage across a stenosis enhances safety of their use. The catheters have been employed successfully to measure phasic pressure gradients across 36 coronary and five renal artery stenoses. Maximal pressure gradients were observed in early diastole for coronary stenoses and in systole for renal artery stenoses, consistent with known differences in phasic flow patterns in these vascular beds. The pressure gradients in patients with coronary stenoses could be markedly increased by injection of contrast medium (Renograffin 76). Relatively poor correlation was observed between the resting pressure gradients and the angiographically defined degree of coronary stenoses.