Branching patterns of intramural coronary vessels determined by microangiography using synchrotron radiation

The intramural coronary artery (IMCA) with a diameter of 50-500 mu m is cri tical for blood supply to the inner layers of heart muscle. We introduced d igital measurement to microangiography using monochromatic synchrotron radi ation and quantified branching patterns of the IMCA, the epicardial coronar y artery (EPCA), and the distal ileal artery (DIA). The pre- and postbranch ing diameters were measured (95-1,275 mu m) in seven dogs. A typical arteri al segment divided into two nearly equivalent branches, and a regression li ne of daughter-to-mother diameter plots was almost identical among the EPCA (y = 0.838x - 16.7 in mu m), IMCA(y = 0.737x - 2.18), and DIA (y = 0.755x 8.63). However, a considerable difference was present at a segment where a proximal IMCA branched off from an EPCA (y = 0.182x + 90.2). Moreover, a p roximal IMCA diameter had no relationship to the branching order from an EP CA. The precision of this method was confirmed by the good correlation of d iameter measurements between two independent observers (r = 0.999, y = 1.02 x - 1.07). In conclusion, using digital microangiography we demonstrated th at the self-similar branching pattern of coronary arteries was discrete at the connection between the IMCA and EPCA.