Gülhane Týp Dergisi 2006; 48: 180-182 OLGU SUNUMU © Gülhane Askeri Týp Akademisi 2006

Azygos vein system abnormality: case report

Necdet Kocabýyýk (*), Tunç Kutoðlu (**), Soner Albay (*), Bülent Yalçýn (*), Hasan Ozan (*)

Summary Introduction Variations seen in the thoracic vein system are Abnormalities related to the azygos system are not rare (1). In a series related to the development of these veins. of 200 cases, Bergman et al. have reported the incidence of this anomaly During the dissection from the posterior medi- astinum of the 60-year-old male cadaver, it 26% (2). These abnormalities are generally explained by the embryolog- was observed that there was no complete ical development. Venous branching of the azygos vein varies (3). There accessory hemiazygos vein, and both posterior are two origins of the azygos and hemiazygos veins. By union of these intercostal veins and hemiazygos vein (above origins and regression of some parts, azygos system comes into its final T10 level) drained bilaterally to the azygos vein. Considering these types of variations is status (4). Different types of structures may occur when these veins important during imaging this region and surgi- develop. Abnormalities about azygos system and especially the variations cal operations. of the hemiazygos veins are not clearly described in the literature. In this Key words: Azygos vein, hemiazygos vein, superior vena cava, venous anomaly presentation absence of the accessory hemiazygos vein and possible causes of these types of variations are discussed in view of the embry- Özet ological development. Azigos ven sistem anomalisi: olgu sunumu Toraks ven sisteminde görülen varyasyonlar, embriyolojik olarak bu venlerin geliþimiyle ilgi- Case Report lidir. Altmýþ yaþýndaki erkek kadavranýn pos- During the dissection of the posterior mediastinum of a 60-year-old teriyor mediastenindeki diseksiyon sýrasýnda; male cadaver; it was observed that there was no complete accessory v.hemiazygos accessoria'nýn tam olarak oluþ- madýðý, iki taraflý posteriyor interkostal ven- hemiazygos vein in the azygos vein system, and posterior intercostal lerin ve v.hemiazygos'un (T10 düzeyinde) veins drained bilaterally to the azygos vein. Right ascending lumbal vein v.azygos'a drene olduðu gözlendi. Bölge ile formed azygos vein and left ascending lumbal vein formed hemiazygos ilgili görüntüleme ve cerrahi giriþimlerde bu tür varyasyonlarýn bilinmesi önem arz eder. vein. After left subcostal vein opened to the hemiazygos vein, hemiazy- Anahtar kelimeler: vena azygos, vena hemi- gos vein joined to the azygos vein at the level of T10 vertebra. The 10th azygos, vena cava superior, venöz anomali posterior intercostals vein joined to the azygos vein by contacting with hemiazygos vein. Left 7, 8 and 9th posterior intercostals veins conjugat- ed and opened to the azygos vein after forming one single root (Figure 1). Inferior vena cava and superior vena cava were normal and their courses were usual. * GATA Anatomi AD **Trakya Üniversitesi Týp Fakültesi Anatomi AD Discussion Ayrý basým isteði: Dr. Necdet Kocabýyýk, GATA Anatomi The cardinal venous complex that constitutes the main venous AD, Etlik-06018, Ankara E-mail: [email protected] drainage system of the embryo appears in the third week of intrauterine growth as two big vessels. These vessels, called anterior cardinal vein and Makalenin geliþ tarihi: 19.09.2005 Kabul tarihi: 15.06.2006 posterior secondary, drain cranial and caudal part of embryo. These two

180 packed. The vein, which is at the left open directly into the azygos vein as side of these veins degenerates in the observed by Bergman et al. In the caudal part of kidney and the vein, case we reported there were underde- which is at the right side constitutes veloped veins, and the posterior postrenal part of inferior vena cava intercostal veins opened into the azy- (4). gos vein. The azygos and hemiazygos veins In the case reported by Caggiati have two origins (1). The first one is and Barberini, two venous structures the terminal part of posterior cardinal that had to be derived from right vein, which combines with superior supracardinal veins were not seen (6). vena cava, and the second one is the Thus in forming venous structure, right supracardinal vein. This embry- there was no main vessel collecting ologic vessel gives rise to right right intercostals veins, and venous ascending lumbal vein. The left drainage was collaterally provided by ascending lumbal vein is composed of the only vessel that was longitudinal- the left supracardinal vein. The left ly moving at the left part. That vessel superior intercostal vein and acces- opens to superior vena cava from left sory hemiazygos vein originate from (6). Figure 1. Azygos and hemiazygos veins. AV, the left posterior cardinal vein and In our case, hemiazygos vein azygos vein; SVC, superior vena cava; HV, this vein simultaneously forms the joined azygos vein at the level of T10 hemiazygos vein; (6,7,8,9,10), posterior inter- costal veins upper part of the azygos vein. The vertebra, so that there was one main part that connects hemiazygos vein to vessel. In Mezzogiorno and Passi- veins meet both at two sides and con- azygos vein is actually remainder of atore's case there were both of the stitute common cardinal vein, which the anastomosis between the left and vessels and there was a transverse opens to sinus venosus. In the eight the right posterior cardinal veins (6). connection between them (1). In the week of embryo an oblique anasto- Azygos veins embryologically gener- case of Özbek et al. hemiazygos vein mosis occurs between two anterior ate from subcardinal veins. The right was absent (7). Fifth and sixth left cardinal veins. This connection subcardinal vein forms azygos vein posterior intercostal veins with third becomes left brachiocephalic vein and the left subcardinal vein forms and fourth opened to left superior when the caudal part of left anterior hemiazygos vein. intercostals vein. In the case of Özde- cardinal vein degenerates. Right ante- A transverse anastomosis is mir et al., in addition to absence of rior cardinal vein and right common formed between them approximately hemiazygos vein, there were superior cardinal vein constitute superior vena at sixth and seventh thoracal verte- intercostal veins that drained this cava. The left anterior cardinal and brae in adults. At the left side, cranial region and the connection vein with the left common cardinal veins, part of this anastomosis is partially the azygos and accessory hemiazygos which are in the caudal part of left atrophied or it remains as accessory veins (8). In both of the cases azygos brachiocephalic vein are mostly hemiazygos vein. In our case acces- vein opened to superior vena cava. regressed (4). Left common cardinal sory hemiazygos vein did not exist Cossina et al. have reported two vein constitutes left oblique vein of due to total regression of the left sub- azygos veins that continue with infe- atrium (5). The beginning part of the cardinal vein and atrophy of veins rior vena cava (9). This case can be left superior intercostals vein gener- forming hemiazygos and accessory accounted for by embryological per- ates from the cranial point of the hemiazygos veins that were embryo- sistence of both supracardinal veins. postcardinal vein, and drains second, logically above anastomosis of right Continuing with inferior vena cava of third and mostly fourth intercostal and left postcardinal veins because of azygos system is associated with the veins. In adults both of posterior car- this, the left posterior intercostal anomalies of superior vena cava and dinal veins constitute the root of veins drained into the azygos vein. azygos system, congenital heart dis- azygos vein and common iliac vein. Bergman et al. have reported the ease, aspleny and polispleny syn- The cardinal vein and supracardinal incidence of incomplete formation of dromes, and abdominal situs anoma- vein gradually take place of posterior hemiazygos and accessory hemiazy- lies (10-12). Congenital heart disease cardinal vein. Both of the supracardi- gos veins as 15% (2). If the hemiazy- should be searched in cases with this nal veins are the last grown vein gos is underdeveloped, its branches kind of anomaly.

Cilt 48 · Sayý 3 · Gülhane TD Azygos vein system abnormality ·181 It is important to determine the Lumbar, renal and associated parietal and azygos continuation of the inferior variations of the azygos system espe- and visceral veins based upon a study vena cava. J Comput Tomogr 1986; cially in the computed tomography of 100 specimens. Surg Gyn Obstet 10: 287-290. 1958; 107: 3-18. 10.Minniti S, Visentini S, Procacci C. and magnetic resonance imaging of 4. Standring S. Gray's Anatomy. The Congenital anomalies of the venae mediastinum. The anomalous azygos Anatomical Basis of Clinical Practice. cavae: embryological origin, imaging venous system may easily be con- 39th ed. Churchill Livingstone, 2005: features and report of three new vari- fused with aneurysm, lymphadeno- 1025-1027, 1045-1050. ants. Eur Radiol 2002; 12: 2040-2055. pathy and other anomalies like tumor 5. Ozan H. Anatomi. 2. baský. Ankara: 11.Vijayvergiya R, Bhat MN, Kumar RM, Klinisyen Týp Kitapevleri, 2005: 192- Vivekanand SG, Grover A. Azygos (7,13,14). It is important to keep in 194. continuation of interrupted inferior mind this kind of variations in the 6. Caggiati A, Barberini F. Partial agene- vena cava in association with sick sinus mediastinal operations or surgery of sis of the azygos vein: a case report. syndrome. Heart 2005; 91: e26. large vessels. Ann Anat 1996; 178: 273-275. 12.Churchill RJ, Wesby G, Marsan RE, 7. Özbek A, Dalçik C, Çolak T, Dalçik Moncada R, Reynes CJ, Love L. References H. Multiple variations of the azygos Computed tomographic demonstra- 1. Mezzogiorno A, Passiatore C. An venous system. Surg Radiol Anat 1999; tion of anomalous inferior vena cava atypic pattern of the azygos venous 21: 83-85. with azygos continuation. J Comput system in man. Anat Anz 1988; 165: 8. Özdemir B, Aldur MM, Çelik HH. Assist Tomogr 1980; 4: 398-402. 277-281. Multiple variations in the azygos 13.Smathers RL, Lee JKT, Heiken JP. 2. Azygos vein. Bergman RA, Afifi AK, venous system: a preaortic interazygos Anomalous preaortic interazygos vein. J Miyauchi R. http://www.anatomyat- vein and the absence of hemiazygos Comp Assist Tomogr 1983; 7: 732-733. lases.org/anatomicvariants/cardiovas- vein. Surg Radiol Anat 2002; 24: 68- 14.Takasugi JE, Godwin JD. CT appear- cular/text/veins/Azygos.shtml (last ac- 70. ance of the retroaortic anastomoses of cessed 17.10.2006) 9. Coscina WF, Arger PH, Mintz MC, the azygos system. AJR 1990; 154: 41- 3. Davis RA, Milloy FJ, Anson BJ. Coleman BG. Concurrent duplication 44.

182 · Eylül 2006 · Gülhane TD Kocabýyýk ve ark.