The effect upon coronary blood flow of coronary ostial intubation with an angiographic catheter.

Fifty-two patients undergoing cardiac catheterization were studied to determine whether intubation of the coronary ostium in the course of coronary angiographic studies interferes with coronary blood flow. Pressure at the tip of the catheter and coronary sinus blood flow were measured continuously during insertion of a No. 7.2 French Judkins' catheter into the left coronary ostium and during withdrawal of the catheter from it. In 48 of the 52 patients, there was no change in blood flow related to manipulation of the catheter. In four patients, either a drop in flow following insertion of the catheter or a rise following withdrawal or both were recorded. Two of these four patients had high-grade obstruction of the main left coronary artery, and in the other two the catheter inadvertently advanced and became wedged. In all four cases, reduction in coronary flow was indicated by a drop in or "ventricularization" of the catheter-tip pressure. It is concluded that in the large majority of instances, intubation of the coronary ostium during coronary angiographic studies causes no interference with resting coronary blood flow, but that monitoring of catheter-tip pressure is an important, as well as a valid, procedure for detecting such an interference if it should occur.