CONCENTRATION OF CONTRAST MATERIAL IN ANGIOCARDIOGRAPHY DURING PHASED AND CONTINUOUS INJECTION

Concentrations of contrast material during phased and continuous ventricular injections were studied by mathematical models.

Formulas of the build up curves of both techniques show that the concentrations depend on the stroke volume ratio, injection flow (initial concentration) and time ratio of systole and diastole.

Continuous ventricular injection results in higher concentrations than are obtained with diastolic intermittent injections. With continuous injection the concentration at the end of the first systole (following the first diastole when the injection has started) will have increased 2 or 2.5 times the value at the end of the first diastole. This high concentration is not necessary for the information and can even reduce the informative content of the pictures.

The continuous injection also has the disadvantage in that during systole there is considerable increase in concentration which generally falls during the following diastole. Thus, continuous injection results in large changes in concentration during the cardiac cycle, whereas the diastolic intermittent injection produces a relatively slow rise during the diastole.

With intermittent diastolic injections during the usual injection time of 3 heart cycles the contrast material concentrations will not rise beyond the necessary level. In over 2,000 injections, the total injection volume was reduced 30 to 60% depending on the patient’s age and hemodynamic condition.

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