Normal variations of the superior vena cava and azygos venous system depiction by CT scan in the adult Thai population

Abstract

Background

Identification of normal variations to the thoracic central venous system anatomy is essential in radiological intervention and cardiothoracic surgery to prevent complications.

Purpose

To estimate the prevalence and pattern of normal variations of superior vena cava (SVC) and azygos venous system as well as factors associated with normal variations of SVC.

Material and Methods

Venous-phase chest CT of 1336 patients were retrospectively reviewed. Age, sex, and underlying disease were recorded. SVC diameter and cross-sectional area were measured to evaluate for associations with normal variations.

Results

The prevalence of normal anatomical variations of SVC and azygos venous system were 0.3% and 1.5%, respectively. Duplicated SVC was the most common variations. The most common variation for the azygos venous system was the connection between the hemiazygos and accessory hemiazygos veins draining into the left brachiocephalic vein (12/1336 cases, 0.9%). The median (interquartile range [IQR]) cross-sectional area compared between normal SVC (297.2 mm²) and duplicated SVC (223.5 mm²) showed a statistically significant difference (P = 0.033).

Conclusion

This study determined the prevalence of rare normal variations of the azygos venous system, a connection between the hemiazygos and accessory hemiazygos veins draining into the left brachiocephalic vein. The prevalence of normal variations of the SVC and azygos venous system in the adult Thai population was similar with that of previous publications. Cross-sectional area was the only factor with a significant association with SVC variations.

Keywords

Normal variation superior vena cava azygos venous system computed tomography

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References

Oliveira

Martins

. Congenital systemic venous return anomalies to the right atrium review. Insights Imaging 2019;10:115–131.

Taha Ali

Ghareep

. Anatomical variant of large mediastinal veins: incidental findings on MDCT chest. Egypt J Radiol Nucl Med 2017;48:81–86.

Ratliff

Yousufuddin

Lieving

, et al. Persistent left superior vena cava: case reports and clinical implications. Int J Cardiol 2006;113:242–246.

Uemura

Suwa

Takemura

, et al. A classification of persistent left superior vena cava considering presence and development of both superior venae cavae, the anastomotic ramus between superior venae cavae, and the azygos venous system. Anat Sci Int 2012;87:212–222.

Sarodia

Stoller

. Persistent left superior vena cava: case report and literature review. Respir Care 2000;45:411–416.

Rao

Banerjee

. The azygos venous system and its anatomical variations. J Evid Based Med Healthc 2016;3:2550–2552.

Burney

Young

Barnard

, et al. CT appearances of congenital and acquired abnormalities of the superior vena cava. Clin Radiol 2007;62:837–842.

Schummer

Fröber

. Persistent left superior vena cava and central venous catheter position: clinical impact illustrated by four cases. Sur Radiol Anat 2003;25:315–321.

Lin

Devereux

Roman

, et al. The right sided great vessels by cardiac multidetector computed tomography. Normative reference values among healthy adults free of cardiopulmonary disease, hypertension, and obesity. Acad Radiol 2009;16:981–987.

10.

Blackmon

Franco

. Normal variants of the accessory hemiazygos vein. Br J Radiol 2011;84:659–660.

11.

Arslan

Cubuk

Ozkaynak

, et al. Absence of the azygos vein. Clin Imaging 2000;24:157–158.

12.

Apte

Patil

Dahiphale

, et al. Incidentally detected rare normal anatomical variation of the hemiazygous venous system on computed tomography thorax. J Mahatma Gandhi Inst Med Sci 2016;21:133.

13.

Taha Ali

Ghareep

. Anatomical variant of large mediastinal veins: incidental findings on MDCT chest. Egypt J Radiol Nucl Med 2017;48:81–86.

14.

Bulja

Beslic

Sarajevo

. Abnormalities of the thoracic veins. ECR [Internet]. 2013 [cited 2022 Oct 15]; Available at: https://dx.doi.org/10.1594/ecr2013/C-0912 (accessed 4 February 2023).

15.

Cha

Khoury

. Persistent left superior vena cava. Radiologic and clinical significance. Radiology 1972;103:375–381.

16.

Bonardi

Valentini

Camporotondo

. Unroofed coronary sinus and persistent left superior vena cava: a case report. J Ultrasound 2012;15:179–182.

17.

McCotter

. Three cases of the persistence of the left superior vena cava. Anat Rec 1916;10:371–383.

18.

Yamadori

Takashima

. A case of the double superior vena cava. Acta Anat Nippon 1966;41:213–221.

19.

Fujimoto

Okuda

Yamamoto

. A case of the bilateral superior venae cavae with some other anomalous veins. Okaiimas Fol Anat Jap 1972;48:413–426.

20.

Nandy

Blair

. Double superior venae cavae with completely paired azygos veins. Anat Rec 1965;151:1–9.

21.

Lawler

Corl

Fishman

. Multi-detector row and volume-rendered CT of the normal and accessory flow pathways of the thoracic systemic and pulmonary veins. Radiographics 2002;22:S45–S60.

22.

Vilde

. Der praeaortale verlauf der V. hemiazygous. Acta Univ Latviensis 1925;12:393–404.

23.

Galwa

Prakash

Khandelwal

. 16-MDCT depiction of accessory hemiazygos vein draining into the left brachiocephalic vein. Indian J Radiol Imaging 2007;17:50–51.