The concept of apparent cardiac arrest as a prerequisite for coronary digital subtraction angiography.

This study was undertaken to evaluate the possible use of digital subtraction applied after selective coronary arteriography. An identical position of the objects with and without contrast medium is an absolute requirement for the application of subtraction techniques. Because coronary arteries are in continuous motion, the subtraction technique cannot be applied without certain precautions. In our study, only images from corresponding moments in the cardiac cycle before and after contrast injection were matched for subtraction, that is, the concept of apparent cardiac arrest. To prevent variations in cardiac contractions due to varying RR intervals, heart rate was controlled by regular right atrial stimulation. Moreover, the stimulation rate and cine frequency were in synchrony, which was effected by triggering both on the frequency of the electric main alternating current (50 cycles/s). In this way, each cardiac cycle contains exactly the same number of frames at corresponding moments. A combination of the application of the concept of apparent cardiac arrest with the subtraction technique in 12 patients resulted in good quality images. Furthermore, better visualization of capillary filling with contrast material was obtained than with conventional coronary arteriography.