Bilateral Lateral Costal Branches of the Internal Thoracic Arteries: A Case Report.

We report a case of bilateral lateral costal branches (LCB) of the internal thoracic artery (ITA). On the left side, the ITA branched from the subclavian artery as a common trunk with the thyrocervical trunk. The left LCB flew into the collateral branch of the fifth intercostal artery after reaching the upper end of the sixth rib and after exiting the left ITA at the upper part of the first rib. The left ITA was disconnected near the second rib because it had been used for coronary artery bypass surgery. The right ITA arose from the anterior surface of the right subclavian artery just after the right ITA diverged from the brachiocephalic artery. The right LCB reached the upper end of the fifth rib and flew into the collateral branch of the fourth intercostal artery. The right ITA descended along the back of the costal cartilages as usual. The mechanism of the development of the LCB is thought to be due to a lateral longitudinal anastomosis connecting the inter-node arteries arising from the dorsal aorta during the embryonic phase. More anatomical and embryological studies are necessary to further elucidate this variant arterial branch.

A Retroaortic Left Renal Vein in a Female Cadaver.

We encountered a case of retroaortic left renal vein (RLRV) during an anatomical dissection course at our medical school in 2017. The case was a female cadaver who was 88 years old at death. Six roots of the left renal vein (RV) arose from the hilus of the kidney and joined to form one left renal vein, crossed dorsal to the abdominal aorta (AA) at the level of the second lumbar vertebra, and then drained into the inferior vena cava (IVC). Two roots joined at the right renal hilus to become the right RV to then drain into the IVC at the level of the first lumbar vertebral body. The reported frequency of RLRV is approximately 2%. Embryologically, the normal anastomosis of the left and right sub-cardinal veins results in the left RV traveling on the ventral surface of the AA. However, in the case presented here, the left RV traveled on the dorsal side of the AA due to the anastomosis of the left and right supra-cardinal veins and regression of the anastomosis between the left and right sub-cardinal veins. If both the dorsal and ventral anastomoses remain, the left RV travels on the dorsal and ventral sides of the aorta. Some of the clinical problems reported in association with RLRV are hematuria and abdominal pain, and the risk of damaging the RLRV during surgery of the posterior abdominal wall. Venous variants as reported herein should be kept in mind when interpreting imaging of the posterior abdominal wall or performing surgery or other invasive procedures near the RLRV.