[Pressure gradients in catheters during digital subtraction angiography].

The F4 and F5 catheters used for digital subtraction angiography are subjected to high pressure gradients. The paper analyses the pressure gradients resulting from contrast media of different viscosities in catheters of varying internal diameters and related to the rate of injection. These are demonstrated diagrammatically. The pressure sequences which occur in F4 and F5 sequences can be demonstrated on an oscillograph. The usual high pressure injections also result in turbulent flow conditions.