Intercoronary communication with unidirectional blood flow.

Intercoronary communication is a rare condition in which there is an open-ended circulation with bidirectional blood flow between two coronary arteries. This report highlights a case of an intercoronary connection between the right coronary and circumflex arteries with unidirectional flow. Selective injection of the right coronary artery showed retrograde filling only of the circumflex artery, but left coronary injection did not fill the right coronary artery.