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Background: This study aimed to classify Azygos vein patterns in the Eastern Indian population. Methods: During the routine dissection of MBBS in the 2018–2020 academic year, 20 formalin embalmed cadavers aged 50–70 were used to classify the azygos system. The cadaver’s age was verified by its entry into our institute’s anatomy register. The register confirmed that all cadavers used for dissection were of Indian origin. Though gender was not compared in this study, it was noted for record purposes by identifying the external genitalia and confirming it to the records. These were the exclusion criteria: 1) No major thoracic surgeries; 2) No major thoracic deformities. Azygos, hemiazygos, and accessory hemiazygos veins were also examined. Results: The Anson & McVay system was used to classify the recruited cadavers’ azygos system. The cadavers were classified into Type-1, Type-2, and Type-3. Type 2 was again subdivided into 5 subgroups and Type-3 into2 sub-groups. In one cadaver, Type-1 was observed, 17 cadavers had Type-2 azygos system and 2 cadavers showed Type-3. Of the 17 cadavers of Type-2, 3 and 7 cadavers had Type-2A and -2B, respectively. Similarly, 4 and 1 cadavers had 2C and 2D patterns, respectively. Also, 2 cadavers showed 2E type. Of the 2 cadavers of Type-3, one was Type -3A and one Type-3B. The termination of the azygos vein vertebral level was between T2 and T4, of the hemiazygos vein was T8 to T11, and accessory hemiazygos veins were between T7 and T10. Conclusion: These variations should be well studied to avoid misinterpretation during radiological investigations and surgical interventions.
ABSTRACT
INTRODUCCIÓN: El sistema venoso ácigos-hemiácigos es imprescindible en el drenaje del tórax. Estos vasos se originan en la etapa embrionaria a partir de las venas supracardinales, con una serie de afluentes que parten de la pared torácica y mediastino principalmente, encontrando variedades, como nuestro hallazgo, mismos que deben ser considerados en la práctica médica. PRESENTACIÓN DEL CASO: Se presenta un caso encontrado en una disección de pieza cadavérica, de sexo masculino, en el cual se halló un tronco venoso paralelo al lado izquierdo de la columna, que resultaría de la unión de las venas hemiácigos; originándose por la confluencia de la vena subcostal y lumbar ascendente, drenando en la vena braquiocefálica del mismo lado, muy parecido a la vena ácigos, sin conexión entre ambas. DISCUSIÓN: Son muchas las variedades reportadas en diversos estudios, encontrando una clasificación de dichas anomalías en tres tipos, correspondiendo nuestro caso a la variedad tipo I, con una incidencia del 1%; dichas alteraciones pueden originarse en etapa embrionaria por la falta de diferenciación de las venas supracardinales. De esta manera, resaltamos la importancia de estas variantes en el ámbito clínico, quirúrgico e imagenológico. CONCLUSIÓN: El presente hallazgo resulta ser un caso muy particular, a diferencia de otros estudios revisados, por lo que sería pertinente ampliar el trabajo para obtener la incidencia del mismo
INTRODUCTION: The azygos-hemiazygos venous system is necessary in the drainage of the thorax. These vessels originate in the embryological phase from the supracardinal veins, with a series of tributaries that begin in the thoracic Wall and mediastinum mainly, finding varieties, such as our finding, which must be considered in medical practice. CASE PRESENTATION: In a male corpse dissection we found a venous trunk parallel to the left side of the vertebral column which would result in the joining of the hemiazygos veins; beginning in the confluence of the subcostal vein and ascending lumbar, draining in the brachiocephalic vein on the same side, similar to the azygos vein, without any connection between them. DISCUSSION: There are many varieties reported in diverse studies, which can be categorized in three types. Ours corresponds to type I, with an incidence of 1%. Such varieties can originate in embryological phase due to the lack of differentiation of supracardinal veins. We can highlight the importance of such varieties in the clinical and surgical fields. CONCLUSION: Our finding is a very particular case, unlike other revised studies, which is why it would be pertinent to further research this topic
Subject(s)
Humans , Middle Aged , Blood Circulation/physiology , Brachiocephalic Veins/abnormalities , CadaverABSTRACT
Objective To investigate the morphology and classification of the atypical azygos venous system,and to provide reference for diagnosis and treatment of mediastinal and thoracic vascular diseases.Methods Thirty cadavers were perfused with 10%formalin solution, and immersed in the solution for one month before dissection.The vertebral levels of termination and diameters of the azygos,hemiazygos and accessory hemiazygos veins were examined.Results There were 24 cases of classical azygos venous system,which contained the azygos, hemiazygos and accessory hemiazygos veins.And there were 6 cases of atypical azygos venous system,which were further divided into 4 sub-groups.Namely,type a(2 cases)which showed an inverted"Y"shape;type b(2 cases)which was single column with hemiazygos and ac-cessory hemiazygos veins absent;type c(1 case)which showed an accessory hemiazygos vein draining into the left brachiocephalic vein;and type d(1 case)with azygos vein and double superior vena cava variation.Diameters of termination of the azygos,hemiazygos and accessory hemiazygos veins were(10.39 ±1.98)mm,(8.51 ±2.28)mm,and(6.29 ±1.56)mm,respectively.The vertebral levels of termination of the azygos,hemiazygos and accessory hemiazygos veins were T 4(83.3%),T7to T10,T4to T8respectively.Conclusion All morphometrical diameters and their termination levels can be used during preoperative CT evaluations before planning invasive mediastinal procedures.The re-sults of this study could be helpful in mediastinal surgery,mediastinoscopy and the surgery of the deformations of the vertebral column in the thoracic cavity.
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The azygos venous system is highly variable in terms of its origin, course, communications, tributaries and termination of the associated veins: this study aimed to classify these anatomical variations. Thirty Thiel-embalmed cadavers aged 4898 years (18 female, 12 male) were examined. The vertebral level of termination and diameter of the azygos, hemiazygos, accessory hemiazygos and the left superior intercostal veins were determined, as well as the termination level of the right superior intercostal vein. The azygos system was classified into 3 types; primitive (type 1), transitional (type 2) and unicolumnar (type 3). Type 2 was further divided into 5 subgroups (A to E) according to the number of retroaortic communications. Type one was observed in 3 % (n=1), type 2 in 87 % (n=26) and type 3 in 10 % (n=3) of specimens. The vertebral level of termination of the azygos, hemiazygos, accessory hemiazygos, right superior intercostal and left superior intercostal veins were between T2 and T3, T6 and T10, T5 and T9, T2 and T4, and T2 and T4 respectively. Identification and understanding these variations are important during preoperative radiological investigations and surgical procedures, especially spinal surgery between T7 and T12 using a left thoracotomy approach, to avoid injuries which may lead to postoperative hematomas.
El sistema venoso ácigos es muy variable en función de su origen, comunicaciones, afluentes y terminación de venas asociadas. Este estudio tuvo como objetivo clasificar las variaciones anatómicas relacionadas con el sistema venoso ácigos. Se examinaron treinta cadáveres embalsamados con la técnica de Thiel, con edades comprendidas entre 48-98 años (18 mujeres, 12 hombres). Se determinó el nivel vertebral de terminación y el diámetro de las venas ácigos, hemiácigos, hemiácigos accesoria e intercostales superiores izquierdas, así como el nivel de terminación del lado derecho de la vena intercostal superior. El sistema ácigos se clasificó en 3 tipos; primitivo (tipo 1), de transición (tipo 2) y unicolumnar (tipo 3). El tipo 2 se dividió en 5 subgrupos (A a E) de acuerdo con el número de comunicaciones retroaórticas. El tipo 1 se observó en 3 % (n = 1), el tipo 2 en 87 % (n = 26) y tipo 3 en 10 % (n = 3) de las muestras. El nivel vertebral de terminación de las venas ácigos, hemiácigos, hemiácigos accesoria, intercostal derecho superior e intercostales superiores izquierda se presentaron entre T2 y T3, T6 y T10, T5 y T9, T2 y T4 y T2 y T4, respectivamente. La identificación y comprensión de estas variaciones anatómicas son importantes durante las investigaciones radiológicas preoperatorias y de los procedimientos quirúrgicos, especialmente en cirugía de columna vertebral, entre los niveles T7 y T12, utilizando un abordaje de toracotomía izquierda, para evitar lesiones que pueden conducir a hematomas postoperatorios.
Subject(s)
Humans , Male , Female , Middle Aged , Aged , Aged, 80 and over , Anatomic Variation , Azygos Vein/abnormalities , Azygos Vein/anatomy & histologyABSTRACT
Background: The anatomical knowledge of the variability of the azygos venous system is important for the surgical interventions of the posterior mediastinum and also during radiological investigations/diagnosis especially CT and MRI. The variant azygos venous system might be confused with thoracic aorta aneurysms, lymphadenopathy and tumours of posterior mediastinum. Methods: The present study was undertaken on 10 embalmed adult human cadavers irrespective of sex, used for undergraduate dissection from the Department of Anatomy, Mandya Institute of Medical Sciences, Mandya. In this present study, formation, course and termination pattern of azygos system of veins was observed in 10 dissected human cadavers. Out of which 2 cadavers showed different types of variations. Results: In the present study, normal azygos venous system was found in 8 specimens accounting for 80%. Variations were found in 2 specimens (20%); one specimen presented with connection between accessory hemiazygos vein and hemiazygos vein, 3 transverse channels across vertebral column and the other specimen showed absence of accessory hemiazygos vein and shifting of azygos vein towards midline. Conclusions: Accurate knowledge about these kinds of variations is very important to identify, especially in the computed tomography and magnetic resonance imaging of mediastinum. The abnormal azygos venous system may easily be confused with aneurysm, lymphadenopathy and other abnormalities like tumor. It is important to keep these kinds of variations in mind while performing the mediastinal operations or surgery of large vessels.
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The azygos venous system vary greatly in theirmode of origin, course,tributaries, anastomoses and termination which resulst predominantly due to its complex embryological development. Azygos venous system develops as right and left azygos venous lines. Right azygos venous line develops into vertical part of azygos vein whereas the left one develops into accessory hemiazygos and inferior hemiazygos veins. These are connected by subcentral/ transvertebral veins. In the present case, we found an atypic drainage pattern of posterior intercostal veins into azygos venous system, left being more variable. Right superior intercostal vein formed by 2nd and 3rd posterior intercostal veins whereas left superior intercostal vein was found to be absent. 2nd, 3rd, 4th& 5th left posterior intercostal veins thus drained into accessory hemiazygos vein. Sixth and seventh left PICVs formed a common trunkwith accessory hemiazygous vein and drained into the azygous vein at T6 level. Eighth one united with the hemiazygos vein and formed a common trunkwhich drained into azygos vein at T8 level. Such variations of the azygos venous system are important for a clinician during mediastinal surgeries to prevent inadvertent hemorrhagic complications.
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Formed by the azygos, hemiazygos and accessory hemiazygos veins, this system is responsible for the venous drainage of the thorax and partially of the abdomen. Abnormalities of this system are not uncommon, and many are referred to in literature. The complete agenesis of the accessory hemyazigos vein is associated with complete regression of the left posterior cardinal vein or atrophy of the left subcardinal vein. The reported case consists of the complete absence of the accessory hemiazygos vein, culminating in the drainage of the 4th, 5th, 6th, 7th and 8th left posterior intercostal veins directly into the azygos vein of a male cadaver. The importance of the theme is due to the necessity of recognizing patterns and frequencies of these variations when facing procedures addressing the mediastinum or the major vessels.