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Home , Brachiocephalic vein, Common cardinal veins, Small cardiac vein

OkajimasLeft Superior Folia Vena Anat. Cava Jpn., with 86(2): Left 55–60, Azygos August, 200955

Left with left azygos vein

By

Mamoru UEMURA1, Akimichi TAKEMURA1, Daisuke EHARA2, Hidehito YASUMITSU1, Yoshiyuki OHNISHI1 and Fumihiko SUWA1

1 Department of Anatomy, 2 Graduate School of Dentistry (Anatomy), Osaka Dental University, 8-1, Kuzuhahanazono-cho, Hirakata-shi, Osaka 573-1121, Japan

–Received for Publication, February 25, 2009–

Key Words: Vein, Left superior vena cava, Left azygos vein, Development, Gross anatomy

Summary: An incidence of a left superior vena cava with a left azygos vein was found in a cadaver during an Osaka Dental University student’s dissection practice session in 2002. The left superior vena cava began from the confluence between the right and left brachiocephalic , and extended directly into the left superior edge of the coronary sinus. No right supe- rior vena cava was observed. The left azygos vein, receiving the bilateral , extended into the left superior vena cava. The developmental mechanism of the left superior vena cava was considered as follows; because the proximal part of the left and the left common cardinal vein remained, and the proximal part of the right ante- rior cardinal vein and the right common cardinal vein degenerated and disappeared. The developmental mechanism of the left azygos vein was considered as follows; because the proximal part of the left remained, and the root of the azygos vein was formed.

Introduction ethics committees of our institutions. The present work conformed to the provisions of the Declaration of Hel- An incidence of the left superior vena cava with the sinki in 1995 (as revised in Edinburgh 2000). left azygos vein was found in a cadaver during an Osaka Dental University student’s dissection practice session in 2002. The left superior vena cava began from the conflu- Results ence between the right and left brachiocephalic veins, and descended vertically, and extended into the left 1. Left superior vena cava superior edge of the coronary sinus. No right superior The left superior vena cava (20.8 mm in diameter, vena cava was observed. The left azygos vein began from 57.6 mm in length) began from the confluence between the left subcostal vein, received the bilateral intercostal the right (14.5 mm in diameter) and veins, and extended into the left superior vena cava. the left brachiocephalic vein (17.0 mm in diameter) at a level with the middle body of the third thoracic vertebra or at the left side of 26.0 mm from midline. This vena Materials and Methods cava descended 30.7 mm vertically, received the left azy- gos vein (10.0 mm in diameter) on the left wall of this This case was observed in an 83-year-old Japanese vena cava. Then, this vena cava descended 28.9 mm ver- female cadaver. This cause of death was the metastatic tically, and extended directly into the left superior edge liver cancer. The length of the vessel and the compressed of the coronary sinus (Fig. 1). diameter were measured with calipers (Pocket Calipers, SHINWA RULES CO., LTD, Niigata, Japan). 2. Right superior vena cava The protocol for the present research did not include No right superior vena cava and this remnant were ob- any specific issue that needed to be approved bythe served (Fig. 1).

Corresponding author: Mamoru Uemura, Department of Anatomy, Osaka Dental University, 8-1, Kuzuhahanazono-cho, Hirakata-shi, Osaka 573-1121, Japan. E-mail: [email protected] 56 M. Uemura et al.

Fig. 1. Photograph (A) and schematic illustration (B) showing the anterior view of the and the great vessels. aoa, aortic arch; asa, ascending ; bt, brachiocephalic trunk; lav, left azygos vein; lbv, left brachiocephalic vein; lca, left common carotid ; liv, left internal ; lsa, left subclavian artery; lsv, left ; lsvc, left superior vena cava; pa, ; rbv, right brachiocephalic vein; rca, right ; riv, right ; rsa, right subclavian artery; rsv, right subclavian vein; ta, thoracic aorta; E, esophagus; H, heart; D, diaphragm; T, .

3. Right brachiocephalic vein 2.0 mm in diameter) extended into the left azygos vein. The right brachiocephalic vein (14.5 mm in diameter, The left azygos vein ran across along the left wall of the 63.6 mm in length) began from the confluence between thoracic aorta (20.0 mm in diameter) from the posterior the right internal jugular vein (4.8 mm in diameter) and to the anterior direction, and extended into the left wall the right subclavian vein (9.1 mm in diameter) at a level of the left superior vena cava. The third to first left inter- with the middle body of the third thoracic vertebra or at costal veins gathered in one, and extended into the left the right side of 34.2 mm from midline. This vein ran azygos vein. The right hemiazygous vein began from the horizontally to the left on the anterior side of the aortic right subcostal vein, received the eleventh to eighth right arch at a level with the middle body of the second tho- intercostal veins, extended into the left azygos vein at the racic vertebra (Fig. 1). anterior side of the ninth thoracic vertebra. The seventh to fifth right intercostal veins extended directly into the 4. Left brachiocephalic vein left azygos vein. The fourth and third intercostal veins The left brachiocephalic vein (17.0 mm in diameter) gathered in one, and extended into the left azygos vein. began from the confluence between the left internal jugu- We could not observe that the second and first intercostal lar vein (16.0 mm in diameter) and the left subclavian veins extended into the left azygos vein (Fig. 2). vein (10.2 mm in diameter) at a level with the middle body of the second thoracic vertebra or at the left side of 6. Heart 32.4 mm from midline. And then, this vein ran inferome- The heart (158 g in weight) was about half weights dially 16.2 mm on the anterior side of the aortic arch (Fig. compared with usually (woman ≥ 70 years old: 329.1 1). ± 66.0 g)1). The coronary sinus (67.6 mm in diameter) received the left superior vena cava (25.6 mm in diam- 5. Azygos venous system eter) at the left superior edge of this sinus. And then, the The azygos venous system in this case was a mirror coronary sinus received three great cardiac veins (about image of a normal case. The left azygos vein (10.0 mm 2.2 mm in diameter), the (1.9 mm in in diameter) began from the left subcostal vein, and diameter), ran behind of the heat, and extended into the ascended along to the left margin of the thoracic verte- right . The inferior vena cava (37.3 mm in diam- bra. The eleventh to fourth left intercostal veins (about eter) and two small cardiac veins (about 2.0 mm in diam- Left Superior Vena Cava with Left Azygos Vein 57

Fig. 2. Photograph (A) and schematic illustration (B) showing the anterior view of the azygos venous system. icv6–11, the 6–11th intercostal vein; lav, left azygos veins; lbv, left brachiocephalic vein; liv, left internal jugular vein; lsvc, left superior vena cava; lsv, left subclavian vein; rbv, right brachiocephalic vein; sub, subcostal vein; L1–L3, the 1–3rd lumbar vertebrae; Th6–12, the 6–12th thoracic vertebrae.

eter) extended into the right atrium (Fig. 3). Discussion

7. Other findings We considered that 1. the frequency of the persistent The brachiocephalic trunk, the left common carotid left superior vena cava in anatomical field, 2. develop- artery, and the left subclavian artery arose directly from mental mechanism of the left superior vena cava and the aortic arch, which was a type A according to Adachi’s 3. developmental mechanism of the left azygos vein, in classification (1928)2). The right subclavian artery (12.0 order. mm in diameter) passed in front of the right scalenus an- terior muscle. This artery arose from the brachiocephalic 1. The frequency of the persistent left superior vena cava trunk (15.0 mm in diameter), ran superolaterally, and in anatomical field sequentially branched into the right vertebral artery (5.2 Adachi (1933)3) reported that the incidence of the mm in diameter), the right costocervical trunk (1.5 mm persistent left superior vena cava was 0.27% in the adult. in diameter), the right thyrocervical trunk (2.0 mm in The present case of the left superior vena cava was the diameter) superiorly, and the right internal thoracic artery first case of its kind in 298 cadavers (596 sides) studied (2.4 mm in diameter) inferiorly. No abnormality was ob- in student’s dissection practice sessions at our facilities served the running and branching of the left subclavian from 1994 through 2003 (10 years), which represents a artery (12.2 mm in diameter), the thoracic duct, the right 0.3% incidence ratio. The present case was classified as lymphatic duct, the vagus nerves and the sympathetic a type IV according to McCotter’s classification (1916)4), trunks. was the fourth report, after Wake (1954)5), Akiyama et al. 58 M. Uemura et al.

Fig. 3. Photograph (A) and schematic illustration (B) of the heart. ①, anterior view; ②, posterior view; ③, lateral view of the left side; ④, lateral view of the right side; cs, coronary sinus; gcv, great cardiac vein; ivco, inferioir vena cava ostium; lvco, left superior vena cava ostium; mcv, middle cardiac vein; scv, ; ARA, auricle of right atrium; RA, right atrium.

(1965)6) and Chiba et al. (1971)7). 3. Developmental mechanism of the left azygos vein In a normal case, in the 6-week-old embryo, the 2. Developmental mechanism of the left superior vena bilateral supracardinal veins appeared, and extend into cava the posterior cardinal veins. In the 7-week-old embryo, In a normal case, in the 4-week-old embryo, the the bilateral supracardinal veins developed inferiorly. common cardinal veins consisted of the paired anterior In the 9-week-old fetus, the anastmosis vein appeared and posterior cardinal veins. The common cardinal veins between the right and left supracardinal veins. In the extended into the sinus venous of the primitive heart. In 12-week-old fetus, the proximal part of the right poste- the 7-week-old embryo, the anastmosis vein appeared rior cardinal vein remained, and the root of the azygos between the right and left anterior cardinal veins. In the vein was formed. The left supracardinal vein separated 12-week-old fetus, the proximal part of the left common the hemiazygos and the accessory hemiazygos veins. The cardinal vein became the coronary sinus, and extended extended into the azygos vein via the into the right atrium. The remained left common cardinal anastmosis vein. The azygos vein extended into the supe- veins were disappeared. The anastmosis vein became rior vena cava8). the left brachiocephalic vein. The right common cardinal In the present case, we considered the developmental vein became the superior vena cava8). mechanism of the left azygos vein following described. In the present case, we considered the developmen- In the 12-week-old fetus, the proximal part of the left tal mechanism of the left superior vena cava following posterior cardinal vein remained, and the root of the left described. In the 12-week-old fetus, the right common azygos vein was formed. The right supracardinal vein cardinal vein and the proximal part of the right anterior was separated the right hemiazygos and the accessory cardinal vein disappeared, the left common cardinal vein hemiazygos veins. The right hemiazygos vein extended and anterior cardinal vein remained. And then, the anast- into the left azygos vein via the anastmosis vein. The left mosis vein became the right brachiocephalic vein, and azygos vein extended into the left superior vena cava (Fig. the left superior vena cava and the coronary sinus devel- 4). oped (Fig. 4). Left Superior Vena Cava with Left Azygos Vein 59

Fig. 4. This diagram illustrates the development of the left superior vena cava and the left azygos vein, rearranged referring to Langman’s Medi- cal Embryology8). A, 4 weeks; B, 6 weeks; C, 7 weeks; D, 9 weeks in the normal case; E, 12 weeks in the normal case; F, 9 weeks in the present case; G, 12 weeks in the present case; acv, anterior cardinal vein; anv, anastmosis vein; av, azygos vein; ccv, common cardinal vein; cs, coronary sinus; hav, hemiazygos vein; hs, hepatic sinusoids; icv, intercostal vein; ivc, inferioir vena cava; lav, left azygos vein; lbv, left brachiocephalic vein; lsvc, left superior vena cava; pcv, posterior cardinal vein; ra, right atrium of the heart; rbv, right brachiocephalic vein; sbcv, subcardinal vein; spcv, supracardinal vein; svc, superior vena cava; K, kidney; M, mesonephros.

In this rare case, we observed the left superior vena our sincere gratitude to the staff of the department of cava. Additionally, we observed the abnormalities of the anatomy, Osaka Dental University for their good advice. azygos venous system and the right subclavian artery. Therefore, we considered that it was necessary to note References other abnormalities. 1) Kurihara K, Kuroda N, Murai T, Yanagida J and Watanabe H. Reconsideration of organ weight in Japanese (1) Heart. Acta Anat Acknowledgments Nippon 1989; 64:495–499 (in Japanese). 2) Adachi B. Das Arteriensystem der Japaner, Bd1. Kenkyusha, Tokyo, 1928; 135–137 (in German). This study was presented at the 16th International 3) Adachi B. Das Venensystem der Japaner, Bd2. Kenkyusha, Tokyo, Congress of the International Federation of Associa- 1933; 68–76 (in German). tions of Anatomists, and at the 109th Annual Meeting of 4) McCotter RE. Three cases of the persistence of the left superior the Japanese Association of Anatomists (Kyoto, Japan) vena cava. Anat Rec 1916; 10:371–383. 5) Wake H. Unu kazo de maldekstra supra kavvejno. Medicina between August 22–27, 2004. We also wish to express 60 M. Uemura et al.

Revuo 1954; 2:41–44. cava without any corresponding vessel on the right side. Acta 6) Akiyama S, Nakanishi T, Iwasaki S and Abe T. A case of unilat- Anat Nippon 1971; 46(3) (suppl): I–2 (abstract in Japanese). eral left superior vena cava. Fukushima J Med Sci 1965; 12:137– 8) Sadler TW. Venous system. In: Langman’s Medical 145. 9th eds. Lippincott Williams & Wilkins, Philadelphia, 2004; 261– 7) Chiba T, Inoue K and Yoshida Y. A case of a left superior vena 269.