Coronary artery-cardiac chamber shunt: cineangiographic analysis.

Coronary artery-cardiac chamber shunts (CA-CC shunts) were observed in 101 out of 2267 consecutive patients (4.5%) receiving selective coronary angiography. In these patients, contrast medium injected into the coronary artery escaped directly into the cardiac chamber. CA-CC shunts were angiographically classified into the following two types. Type I: The endocardial layer was diffusely opacified, and contrast medium escaped into the cardiac chamber on systole (n = 83). Type II: Contrast medium escaped directly into the cardiac chamber via an undilated branch (n = 11). Type I and type II shunts were observed simultaneously in 7 patients. It is speculated that type I is a shunt via a persistent arterio-sinusoidal vessel, while type II is a shunt via a persistent arterio-luminal vessel. Both types were observed frequently (24.9%) in hypertrophic cardiomyopathy. The degree of CA-CC shunts in hypertrophic cardiomyopathy was not influenced by the presence or absence of myocardial squeezing. CA-CC shunts are considered to be due to an abnormality in the coronary microcirculation of the myocardium. We describe the angiographic features of the two types of CA-CC shunt and discuss their pathophysiological significance.