Two cases of coronary venous drainage by a persistent left superior vena cava in cat.код для вставкиСкачать
TWO CASES O F CORONARY VENOUS DRAINAGE BY A PERSISTENT LEFT SUPERIOR VENA CAVA I N CAT FRED N . ZEINER Department of Zoology, University of Denver, Denver, Colmado This condition was seen in two cats in the same group during classroom dissection. There are few previous reports. Prows (’43) summarizes them and adds a case from man. The only previous report of this anomaly in cat is that of Grant (’17). Chouke (’39) gives an extensive bibliography of related anomalies. DESCRIPTION AND DISCUSSION A sizeable vein joined the left innominate at the junction of subclavian and external jugular veins and extended toward the heart in a nearly straight line. It differed from the often reported “left precava,” which empties into the right atrium through the coronary sinus, in having direct continuity with v. cordis magna and there was no coronary sinus. The main ventral branch of the v. cordis magna attained the dorsal side by running through the coronary sulcus. Here at the dorsoanterior portion of the left ventricle it received the dorsal contribution and also attached to the left precava. There was nothing extending transversely through the coronary sulcus from this point toward the right atrium in the normal position of the coronary sinus. There was no indication of a coronary orifice or Thebesian valve in either cat. With one exception the literature of persistent left precavae mentions the existence of a coronary sinus and, in this case (Basu, ’32), the portion of the left precava receiving the coronary veins would be described by others as a coronary sinus. 275 T H E ANATOMIOAL RECORD, V O L 129, NO. 3 NOVEMBEE 1957 276 FRED N. ZEINER It is difficult to bound the sinus when the left precaval drainage is into the right atrium unless the portion of the vessel in the coronary sulcus and receiving the coronary veins shows n distinct swelling. Identification is simpler in cases of coronary drainage through the left precava to the left innominate vein. I n some (Prows, ’39 ; Reed, ’38) a blindly-ending, pouch-like structure in the appropriate location and with a transverse orientation therein receives the coronary veins and in turn connects with the left precava. Grant’s interpretation (’17) of a coronary sinus is questioned. The structure so-labelled in his figure appears to be merely that part of the ventral branch of v. cordis magna which runs through the coronary sulcus on the left side. It is believed that his case was similar to those reported here. A developmental explanation has both obvious and clouded features. The left precava results from persistence of the more proximal part of the left anterior cardinal vein. Confusion in the story of coronary sinus development makes it difficult to delimit the embryonic structures that have not persisted. It appears that the channel between v. cordis magna and the atrium atrophied before establishment of a large coronary return and before atrophy of the left precardinal segment. The suggestions advanced by Grant (’17) seem to offer reasonable explanation for this. The occurrence of a rare anomaly in two specimens of the same shipment raises the possibility of a genetic basis. It is probable that the two specimens were sibs, but this, unfortunately, could not be determined. SUMMARY Coronary venous drainage by a persistent left precava is described in two cats. I n neither was a coronary sinus present. The possibility of a genetic basis for the anomaly exists. LITERATURE CITED BASU,B. N. 1932 Persistent ‘left superior vena cava’, ‘left duct of Cuvier’, and ‘left horn of the sinus venosus’. J. Anat., 66: 268-270. ABERBANT CORONARY VEXOUS DRAINAGE 27 7 CHOUKE,K. S. 1939 A ewe of bilateral superior vena cava in an adult. Anat. Rec., 7 4 : 151-157. GRANT,8. B. 1917 A persistent supcrior vcna cava sinistra in the eat tran8mitting coronary blood. Anat. Rec., 13: 45-49. PROWS, M. A. 1943 Two cases of bilateral superior venae cavae, one draining a closed coronary sinus. Anat. Rcc., 67: 99-106. REED,A. F. 1938 A left superior Venn cava draining the blood from a closed coronary sinus. J. Anat., 73: 195-197.