Angiography of the coronary circulation in living dogs using timed diastolic injections.

Reliable demonstration of the coronary arteries in the living is possible if special techniques are used. A historical summary and review of various methods will be found in publications by Dotter and Frische (1958) and Michell (1960). In a previous communication from this department (Sloman and Jefferson, 1960) a technique of coronary arteriography in living dogs was described using acetyl-choline cardiac arrest. It was thought, however, that this procedure was potentially dangerous and a safer method was sought. The present investigation was undertaken to try the effect of timing injections of radio-opaque medium to occur in diastole, a method suggested by Richards and Thal (1958). Maximal coronary flow occurs during ventricular diastole, while flow may be actually reversed in systole (Green et al., 1935; Gregg, 1950). Therefore, medium injected into the root of the aorta during diastole should result in good coronary artery filling, whereas systolic injection should produce poor opacification.