Azygous Venous System -Anatomical Variation and Its Clinical Significance (original) (raw)
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Surgical and Radiologic Anatomy, 2002
Multiple variations of the azygos venous system were detected during routine dissection. The hemiazygos vein was underdeveloped. On the left side of the thorax, posterior intercostal veins between the 8th and 11th intercostal spaces and the subcostal vein drained into the azygos vein independently. In addition, the posterior 4th, 5th, 6th and 7th intercostal veins united and formed two superior and inferior trunks. The superior common trunk, at the level of the T4 vertebra, crossed the vertebral column obliquely, lying anterior to the aorta and posterior to the esophagus, opening into the azygos vein at the level of the T4 vertebra. The other structures in this part were normal. There were different courses of the azygos vein system. This variation is important in mediastinal surgery and also in the interpretation of radiographs.
European journal of anatomy, 2019
The azygos venous system varies greatly in mode of its origin, course, number of vertical channels , number of horizontal anastomoses and nature of termination. Anatomical knowledge of such variations is of immense importance in radiological investigations and surgical intervention of posterior mediastinum pathologies. The present study was undertaken on 30 adult embalmed cadavers aging between 40-65 years, to determine the anatomical variations of the azygos system and to classify accordingly. The vertebral level and diameter of the azygos, hemiazygos, accessory hemiazygos veins at their origin and terminations were also observed. The azygos system was classified into 3 types as per the Anson & McVay system: primitive (type I), transient (type II) and unicolumnar (type III). Type II was further subdivided into 5 subgroups (A to E) according to the number of retro-aortic communications. Type I was observed in 1 case (3.33%), type II in 27 (90%) and type III in remaining 2 cases (6.67%). The vertebral level of termination of the azygos, hemiazygos, accessory hemiazygos veins were between T2 and T3, T6 and T10, T6 and T9 respectively. Variations in the formation of azygos system is not an uncommon phenomenon and these variations may easily mislead the radiologists while performing CT/MRI of posterior mediastinum or cardiothoracic surgeons while performing vascular surgeries in this region.
Migration of central lines from the superior vena cava to the azygous vein
Clinical Radiology, 2012
cases of central venous access catheters migrating from the superior vena cava to the azygos vein in order to raise radiologists' awareness of this possibility. MATERIALS AND METHODS: This is a retrospective review of the clinical history and imaging of 11 patients whose central line migrated from the superior vena cava to the azygos vein. The time course of migration, access route of the catheters, outcome, and depth of placement in the superior vena cava were evaluated. RESULTS: All of these catheters were placed from the left; six through the subclavian vein, four as PICC lines, and one from the left internal jugular vein. Seven of the catheters were originally positioned in the superior vena cava. Four of the catheters were originally positioned in the azygos vein and were repositioned into the superior vena cava at the time of placement. The time to migration ranged from 2 to 126 days, average 43 days. In three cases, the migration was not reported at the first opportunity, resulting in a delay in diagnosis ranging from 10 to 27 days. All but one of the catheters extended at least 3.5 cm (range 1.8e7 cm) below the top of the right mainstem bronchus when in the superior vena cava. CONCLUSION: Risk factors for migration into the azygos vein include placement from a leftsided approach and original positioning in the azygos vein with correction at placement. The depth of placement in the superior vena cava was not a protective factor. It is important to recognize migration because of the elevated risk of complications when central lines are placed in the azygos vein.
Multiple variations of the azygos venous system
Surgical and Radiologic Anatomy Sra, 1999
In a dissection performed in our department, we observed multiple variations of the azygos venous system. The hemiazygos vein was absent. The posterior 8th, 9th, and 10th intercostal veins united and their common trunk crossed the vertebral column obliquely lying anterior to the aorta and posterior to the esophagus and opening into the azygos vein at the level of T7-T8 vertebrae. The 7th left posterior intercostal vein also crossed the column anteriorly and joined the common trunk. The present report identifies the variable positions and courses of the veins related to the azygos system. It is important to keep in mind that different courses of the azygos system do exist, so that extra caution is required during surgery of the mediastinum and also in appropriately interpreting the radiographs.
A Study on Azygos System of Veins and Venous Aneurysm
Introduction: The azygos system of veins drains most of the posterior abdominal and thoracic wall. It also receives mediastinal, bronchial and oesophageal veins. The azygos vein serves as an important channel of communication between superior and inferior venacava. The vein also communicates with the vertebral venous plexus. Materials & methods: The present study on azygos system of vein was carried out in the Department of Anatomy, SIMS. A total of 32 cadavers irrespective of age and sex were used for this study. The azygos vein was traced right from its formation. Its course in the posterior mediastinum and termination into superior venacava, any variation in the origin, termination and its tributaries such as hemi azygos and accessory hemi azygos vein was carefully observed and photographed. Results: Variation in the drainage pattern of hemi azygos and accessory hemi azygos were observed in seven specimens of which three specimens show a two way drainage of hemi azygos vein and accessory hemi azygos vein into azygos and left brachiocephalic vein. Conclusion: Knowledge of such variations exhibiting different drainage pattern is significant during mediastinal surgeries as it may poses a potential source of haemorrhage,and aneurysm of azygos systems of veins. Such abnormal communications may also lead to misinterpretation of CT and MRI findings of posterior mediastinum. I.
Anatomical Variation of the Azygos System of Veins - Case Report
Journal of Morphological Sciences, 2019
Introduction The azygos system of veins (ASV) is a very variable structure characterized as a communication between the inferior and superior vena cava, having the azygos vein (AV), the hemiazygos vein (HV), and the accessory hemiazygos vein (HAV) as its main components, which are responsible for the mediastinal viscera and for the thoracoabdominal wall drainage. The aim of the present study is to report an anatomical variation found in a male cadaver at the Laboratory of Anatomy of the University Center of UNIFACISA, Campina Grande, PB, Brazil. Case Report In the posterior mediastinum, the union of the HV, of the HAV, and of the 8th left posterior intercostal vein formed a common trunk at the level of the left 8th intercostal space, crossing the mediastinum posterior to the aorta artery, ending up in the AV, in the right hemithorax. Conclusion The study of the anatomical variations of the ASV is important and will provide knowledge for physicians not to confuse them with pathologic...
The azygos vein pathway: an overview from anatomical variations to pathological changes
Insights into Imaging, 2014
The azygos venous system represents an accessory venous pathway supplying an important collateral circulation between the superior and inferior vena cava. The aim of this article is to revise the wide spectrum of changes ranging from normal to pathological conditions involving the azygos system. Teaching points • The azygos vein is a collateral venous pathway, becoming a vital shunt if major pathways of venous return are obstructed. • In azygos continuation, the azygos vein becomes significantly enlarged due to inferior vena cava interruption. • Fibrosing mediastinitis is an underestimated acquired disorder. • Fibrosing mediastinitis induces a variable engorgement of collateral veins. • Fibrosing mediastinitis leads to superior vena cava syndrome.
2014
The azygos system of veins varies greatly in their mode of origin, course, tributaries, anastomoses and termination. These deviations result predominantly due to its complex embryological development. Azygos venous system develops as right and left aygos venous lines dorsolateral to the aorta. Right azygos venous line develops into vertical part of azygos vein and left one gives rise to a set of longitudinally arranged veins which develops into superior or accessory hemiazygos veins and inferior hemiazygos vein. These are connected by subcentral/ transvertebral veins which vary extremely. The number of such transvertebral veins has been reported from zero to five in the previous literature. In the present case, a continous left azygos venous line was reported which drained into right azygos vein through a single transvertebral connection, thus there is only one transvertebral vein and the left azygos line is not divided into superior and inferior hemiazygos veins. Anatomical knowledge of such variations is important for a clinician while doing mediastinal surgery or to interpret CT/ MRI images.
Left superior vena cava with left azygos vein
Okajimas Folia Anatomica Japonica, 2009
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 veins, and extended directly into the left superior edge of the coronary sinus. No right superior vena cava was observed. The left azygos vein, receiving the bilateral intercostal veins, 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 anterior cardinal vein and the left common cardinal vein remained, and the proximal part of the right anterior 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 posterior cardinal vein remained, and the root of the azygos vein was formed.