Intercoronary Communication with Unidirectional Blood Flow

ABSTRACT: 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. J INVAS CARDIOL 2004;16:269–270 Key words: angiography, coronary anomaly, coronary artery Intercoronary communication is an extremely rare condition in which there is an open-ended circulation with bidirectional blood flow between two coronary arteries. This anomaly is usually seen between the right coronary artery and circumflex artery. We present a case of an intercoronary connection with unusual unidirectional blood flow. Case Report. A 56-year-old man presented to our institution with atypical chest pain. Physical examination was normal, with arterial blood pressure of 130/70 mmHg and a regular heart rate of 74/min. Echocardiography and resting electrocardiography (ECG) findings were also within normal limits. Exercise ECG revealed 1 mm horizontal ST depression in the inferior leads. The patient underwent coronary angiography and ventriculography using the Judkins method via the right femoral artery. Left ventriculography was normal. Right coronary injection showed retrograde filling of the circumflex artery from the distal right coronary artery (Figure 1). No stenosis or angiographic lesions were observed in the right coronary artery or the circumflex artery. Additionally, no retrograde filling of the right coronary artery from the circumflex artery was observed (Figure 2). Discussion. Interarterial intercommunications can be found in some regions of the human arterial system: 1) the superficial volar arch of the hand, with communication between the ulnar and radial arteries; 2) the circle of Willis; 3) the intestinal branches of the superior mesenteric artery that form multiple arches; 4) the gastric artery that extends from the right to the left gastroepiploic artery.¹ Intercommunication is very rare, however, in the human coronary system. The first case regarding coronary intercommunication was presented nearly 30 years ago and only a few cases have been reported since then.^2–6 Intercoronary communications are usually found between the right coronary artery and the circumflex artery, as in our case, but they may also be found between the right coronary and left anterior descending arteries.⁷ To the best of our knowledge, all of the reported intercoronary communications between the right coronary and circumflex arteries are bidirectional, in that both coronary arteries fill via communications when contrast media is given to the other one. Interestingly, blood flow in our case was unidirectional from the right coronary artery to the circumflex, but not from the circumflex to the right coronary artery. It is not clear why this difference in our case exists compared to all other reported cases, or what importance it may have. These communications have been found in the absence of coronary artery disease, although myocardial perfusion scans occasionally were abnormal at the connecting site.⁸ Consistent with this finding, a Tl 201 perfusion scan showed a reversible filling defect in our patient’s inferior segments. The mechanism of this reversible ischemia is not known. This anomaly may be misinterpreted as indicative of a functioning collateral vessel for unrecognized severe proximal coronary artery obstruction. A large collateral vessel, as opposed to a true intercoronary communication, is the likely case if there is a severe stenosis or total occlusion in any coronary artery. Moreover, the real intercommunication in the coronary system is benign and may serve as a collateral source in the event that a coronary artery obstruction develops.⁹ As a result, intercoronary communication is a very rare and benign condition. The small number of cases reported in the literature all report bidirectional communications. To the best of our knowledge, the present case is the first reported intercoronary communication with only unidirectional flow.