T H E CORONARY BLOOD SUPPLY I N T H E CAT DAVID I. ABRAMSON, J. HAMILTON CRAWFORD AND GEORGE H. ROBERTS1 Biooklyn, New P o r k FOUR FIGURES It is the purpose of this report to present a description of the coronary blood supply in the cat as revealed by injection of the blood vessels. Seventy normal hearts were used; no special attention being paid to the age of the animals. The coronary arteries were filled with an injection mass consisting of plaster of Paris and pulverized colored chalk. The hearts were then washed free of any excess injection mass, dehydrated and cleared in oil of wintergreen, following the technique advocated by Gross.2 RIGHT CORONARY ARTERY The right coronary artery arises from the aorta and extends to the right for a short distance to enter the auriculoventricular groove, in which it runs over the anterior surface of the heart, around the margo acutus (lateral border of the right ventricle) and then posteriorly. I n about two-thirds of the specimens, it gives off near its origin a conus branch which crosses the base of the pulmonary artery to divide into fine twigs. Further along in its course, six or seven other branches arise, four or five of which run downward over the anterior surface of the right ventricle, while the remaining two extend over the margo acutus. These perpendicular branches, in turn, give off fine vessels to either side which anastomose with one another on the outer wall of the right ventricle. From the Department of Physiology, Long Island College of Medicine. * Gross, L. : The blood supply t o the heart. New York, Iloeber, 1921. 25 26 I). I. ABRAMSON, J. H. CRAWFORD A N D G. I€. ROBERTS Posteriorly the right coronary artery remains in the anricnlo-ventricular groove for variable distances. I n about 33 ycr cent of cases it plays an unimportant role in supplying the posterior surface of the heart. I n this series (fig. 1) it either tiiriis to run down the right ventricle parallel to and to the right of the posterior interventricular sulcus, or it gradually terminates by dividing into braiiches which extend 2 Fig. 1 Posterior surface of heart. A , posterior descending branch of circumflex artery running in interventricular suleus ; B, right coronary artery. Fig. 2 Posterior surface of Iiexrt. A, circumflex division of left coronary artery ; R, large branch of circumflex division extending over inargo obtusus. f o r short distances over the lateral basal portion of the posterior surface of the right ventricle. I n the remaining 65 per cent of cases, the right coronary artery supplies posteriorly all of the right ventricle and variable portions of the left ventricle (fig. 3). I n about one-half of this series, it turns abruptly a t the posterior interventricular groove and, a s the posterior descending artery, runs almost perpendicularly downward in the direction of the apex. During its course in CO1:ONABY BLOOD SUPPLY I N THE CAT 27 the posterior groove i t gives off several branches to either side and also a number of small twigs which, arising from the under surface of the main branch, penetrate the septum at right angles. I n the remaining half of the series (i.e. of the 65 per cent of cases) the right coronary artery continues on to the posterior surface of the left ventricle, giving off at the 3 Fig. 3 Posterior surfncc of heart. A , right coroiiary artery exteiidinp on t o basal portion of left veiitricle ; R, p s t e r i o r tlesccnding division of right coronary artery rumiiiig in i~itervcntricular sulcus ; C, perpendicular twig of circumflex division of tlw left eoroiiary artery ; D, circumflex division of left coronary artery. Fig. 4 Anterior surface of henrt. A , anterior descending division of l e f t coronary artcry ruimiiig i n the anterior intervcntricul:ir sulcus ; €3, coiius branch of auterior desceiidiug division. point where it crosses the posterior interventricular groove, one o r two large branches which follow practically the same course and ramification as the posterior descending artery (fig. 3 B ) . The right coronary artery, itself, in these cases eventually divides into small branches which coiirse obliquely d o ~ v i i u ~over d the left ventricle to supply from one-quarter to one-half of its posterior surface adjoining the interventricular groove (fig. 3 A ) . 28 D. I. ABRAMSON, J. H. CBAWFORD A N D G. H. ROBERTS LEFT CORONARY ARTERY The left coronary artery arises from the aorta, turns to the left to run in the auriculo-ventricular groove for a short distance, and then divides into its two main branches, the anterior descending and circumflex arteries. Circzhmflex artery. The Circumflex artery continues in the groove, proceeding to the left over the anterior surface and around the obtuse border of the left ventricle. I n a number of instances, it gives off near its origin one or two branches which in their course almost bisect the angle formed by the anterior descending and circumflex arteries. I n some hearts it is difficult to determine whether these vessels arise from one o r the other of the subdivisions of the left coronary artery, or from the main branch itself. They extend obliquely downward over the anterior surface of the left ventricle for varying distances, some ending on the anterior surface, while others reach the obtuse border of the heart and then course in the direction of the apex. F u r t h e r along, the circumflex gives off a variable number of branches, two o r three of which extend almost perpendicularly downward over the anterior surface of the left ventricle, while one o r two course over the margo obtusus. Of the latter, one is usually rather large, its terminal branches continuing as far a s the apex of the left ventricle (fig. 2 B ) . I n its posterior course there arise from the circumflex a r tery three to four branches which extend downward over the surface of the left ventricle (fig. a), the circumflex itself remaining in the auriculo-ventricular groove for varying distances. I n 65 per cent of cases, it leaves the auriculo-ventricular groove at some point between the obtuse border of the heart and the posterior interventricular groove. I n these instances it either gradually terminates by dividing into two or three branches which extend f o r short distances over the posterior surface of the left ventricle, or the main vessel itself runs down over the ventricle, giving off twigs to either side and ending about midway between base and apex. I n all of these hearts, branches from either the right coronarJ- a r - CORONARY BLOOD SUPPLY I N THE CAT 39 tery, its posterior descending division, or from both, course over the posterior surface of the left ventricle (fig. 3 ) . In the other 35 per cent of cases the circumflex artery remains in the auriculo-ventricular groove until it reaches the posterior interventricular groove in which it proceeds toward the apex a s the posterior descending a r t e r y (fig. 1A ) . During its course, the latter gives off a number of branches which either extend on to the basal portion of the posterior surface of the right ventricle, supply the adjoining portion of the left ventricle, or penetrate the septum at right angles. I11 some specimens the circumflex artery leaves the auriculo-ventricnlar groove a short distance to the left of the posterior interventricular groove and in these cases it runs down the posterior surface of the left ventricle parallel to the groove. Aiztcrior desceizdiizg artery. A t its origin the anterior descending artery leaves the auriculo-ventricular groove and turns abruptly downward to run for variable distance in the subepicardial fat overlying the anterior interventricular groove (fig. 4). I n the majority of cases it breaks up into its sub-branches at a point about two-thirds the distance from base to apex ; however, in some hearts the division takes place in the upper third of the anterior interventricular sulcus. In the latter instances there a r e usually two terminal branches, one of which continues in the sulcus almost a s far a s the apex, while the other extends obliquely to the left over the anterior surface of the left ventricle. Both give off twigs which supply the lower halves of the right and left ventricles adjoining the sulcns. In those hearts in which the division of the anterior descending artery takes place at the lower level, the terminal branches, also two in number, continue downward, one remaining in the sulcus and the other generally extending somewhat to the left. Near its origin, the anterior descending artery in about twothirds of the cases, gives off one or two branches to the right which extend across the lower border of the conus arteriosus and then break up into fine twigs (fig. 4). These, in a number of hearts, course a short distance downward over the part of 30 I). I. ABRAMSON, J. H. C R A W F O R I l A N D G. H. ROBERTS the riglit ventricle close to the anterior sulcus. Other large branches, varying in number from three to six, also arise from the right side of the anterior descending artery a t intervals and a r e distributed over the adjoining portion of the right ventricle a s f a r a s its apes. F r o m the left side of tlie artery three to seven vessels arise which extend on to the anterior aspect of the outer wall of the left ventricle, some running horizontally toward the obtuse border, others descending obliquely in the direction of the apes. From these, in turn, arise numerous fine vessels wliicli extend over a great part of the anterior surface of the left ventricle to aiiastomosc with branches from the circumflex artery. Twigs which penetrate the septum for varying distances a r e given off also from the under surface of tlie anterior desceiidiiig artery. SUMMARY The coronary blood vessel distribution in the cat was investigated in seventy injected hearts. On tlie outer surface of the heart anteriorly, the arrangement was found to be relatively constant. Generally, the right ventricle was supplied by tlie perpendicnlar branches of tlie right corollary artery (except for a strip adjoining the anterior interventricular sulcus), the left ventricle by branches of the left coronary artery. Posteriorly, the blood vessel distribution varied. I n 65 per cent of cases the right coronary artery supplied all of the riglit ventricle and varying portioiis of the left ventricle adjoining the posterior interventricular sideus, the rest of the left ventricle receiving its supply from the left coronary artery. I n the remaining 35 per cent of cases the left coronary artery supplied all of the left ventricle and the adjoining part of the riglit ventricle, while the riglit coroiiary supplied only a small p a r t of the riglit ventricle. In the majority of cases, the septum received its supply from peiietratiiig braiiches of both right and left corollary arteries, while in tlie remaining hearts, wholly from braiiclics of the latter.