An Analysis of Several Factors Influencing Injection Rates in Angiography

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Abstract
The experienced angiographer is presumed to know well his tools. The neophyte, however, may need guidance in the choice of catheter, contrast medium, and injection pressure. The authors have investigated flow rates through small-bore catheters with representative media, since with the increased use of the Seldinger percutaneous technic as well as the wide usage of angiography in children, the smaller caliber angiographic catheters are of great import. Flow through catheters was analyzed in the most rational fashion, namely, in grams of iodine per second. To correct another deficiency of previous studies only contrast media of low toxicity were compared. Last, a much-needed comparison of the capacities of high-pressure injectors was made. Equipment and Methods Contrast Media: The media tested were the low-viscosity Hypaque 50 per cent, medium-viscosity Renovist and Angio-Conray, and the highly viscid Hypaque 90 per cent. Other pertinent physical data for the present-day media are listed in Table I. Fifty per cent Hypaque contains only sodium diatrizoate. Ninety per cent Hypaque contains sodium and methylglucamine diatrizoate in 1:2 ratio; Renovist in 1:1 ratio. Angio-Conray contains only sodium iothalamate. Measurement Technics: All tests were performed at room temperature, 24 to 26 ° C. Injectors were employed with a fully loaded syringe, ejecting in the range of 50 ml. for a complete thrust. Timing of the complete injection for the Shipps apparatus was by an electric clock, for other injectors by stop watch. Contrast medium was injected through a catheter into a collecting flask, and duplicate or triplicate injections were made to check the reproducibility of our measurements. An adequate number of injections were made to study the performance for each combination of catheter, contrast medium, and injector, with the following exceptions: the 80-cm. lengths of catheter were omitted from the Cordis, Amplatz, and Phelan injection systems tested, as was the injection of 90 per cent Hypaque through the green catheter with the Shipps injector and the glass Lehman syringe. The Shipps, Cordis, and Amplatz injectors were tested at 150, 200, and 250 pounds per square inch (psi) pressure on the dial of the apparatus, the Phelan injector at 50, 75, and 100 pounds dial pressure. Catheters: The green and yellow Ödman (11) radiopaque polyethylene catheters were tested in lengths of 60, 80, and 100 cm. The internal diameter for the green catheter is 1.3 mm., for the yellow2 1.5 mm. Connection of catheter to syringe was by means of Clay-Adams fittings. In the distal 2 cm. of each catheter, 6 round side holes of 1 mm. diameter were bored with regular spacing with the tool provided by the manufacturer (Kifa) for this purpose. The tip of the catheter was open and not tapered. The same catheter was used in all the tests, except when rupture occurred. The new catheter was then tested so its flow rates conformed to the original.

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