VARIATIONS OF ARCH OF AZYGOS VEIN: AN ANATOMICAL OVERVIEW WITH CLINICAL IMPORTANCE

Address for Correspondence: Dr. Santosh Manohar Bhosale, Associate Professor, Department of Anatomy, S.S. Institute of Medical Sciences, Davangere577005, Karnataka, India. Mobile No: 9945316042 E-Mail: drsantoshbhosale07@mail.com Background: The azygos venous system represents an accessory venous pathway supplying an important collateral circulation between the superior and inferior vena cava. The azygos vein is a collateral venous pathway, becoming a vital shunt if major pathways of venous return are obstructed. Material and Methods: A total of 36 cadavers and dissected specimens were studied. A thorough dissection of the mediastinum was done after the removal of heart and the lungs. The shape, level of termination, dimensions and course & relations of arch of azygos vein was noted on the right side. The diameter of the inferior vena cava was also measured. Observations and Results: most commonly the arch forms an inverted U shaped course. 89% of the case the azygos vein was opening into extra-pericardial part of superior vena cava at a mean distance of 42.5mm from the formation In 19 (53%) cases out of 36 it was opening into superior vena cava at the level of T4. Next commonest level of opening (14%) was at the junction of T3-T4. length varied from 28 to 48 mm. The mean width of IVC was 18 mm +/3.5mm. It was observed that the diameter of IVC is inversely proportional to width of azyos vein. Conclusion: In the present study the normal variations of the morphometry of azygos vein is noted. It is clear that the diameter of SVC is inversely proportional to that of Azygos vein. KEY WODS: Arch, Azyos vein, Inferior Vena Cava, Superior Vena Cava. INTRODUCTION International Journal of Anatomy and Research, Int J Anat Res 2017, Vol 5(3.2):4251-56. ISSN 2321-4287 DOI: https://dx.doi. org/10.16965/ijar.2017. 299 Access this Article online Quick Response code Web site: International Journal of Anatomy and Research ISSN 2321-4287 www.ijmhr. org/ijar.htm DOI: 10.16965/ijar.2017. 299 1 Associate Professor, Department of Anatomy, S.S. Institute Of Medical Sciences, Davangere, Karnataka, India. *2 Associate Professor, Department of Anatomy, S.S. Institute Of Medical Sciences, Davangere, Karnataka, India. Received: 15 June 2017 Peer Review: 15 June 2017 Revised: None Accepted: 03 Aug 2017 Published (O): 31 Aug 2017 Published (P): 31 Aug 2017 or, rarely, into the right brachiocephalic vein, right subclavian vein, intrapericardial SVC, or right atrium [1]. It may open directly into the right atrium (ascribed to the embryonic disappearance of the right common cardinal vein). The azygos occasionally opens into the right brachiocephalic or even the right subclavian (believed to be caused by an elongated embryonic right common cardinal vein) [2]. The azygos venous system represents an accessory venous pathway supplying an important collateral circulation between the superior and inferior vena cava. The azygos vein is a collateral venous pathway, becoming a vital shunt if major pathways of venous return are obstructed. At T5–T6, it arches ventrally just cephalad to the right main bronchus and drains into the SVC