An analysis of factors determining delivery rates of liquids through cardiac catheters.

Abstract

To obtain optimal opacification of the cardiovascular system it is desirable to inject angiographic contrast medium at rapid and reproducible rates. All too often maximum diameter and minimum length of the catheter are determined by patient size. While this is a restriction, injection pressure, temperature, and the particular contrast agent are still available as variables. As opacification depends on the delivery rate of iodine rather than its volume, there are practical limitations to the benefits gained by increasing iodine content as opposed to losses incurred by-concomitant increases in viscosity. Previous attempts at analysis have relied on mathematical formulations for laminar and/or turbulent flow (1–4). As we shall see, since catheter flows encompass both ranges no one of these formulas is applicable for flows generated by pressure injectors. These flows are predictable by the standard engineering technic which plots friction factor and Reynolds number for tube flow. Material and Methods The cont...