A Unique Variation of Azygos System of Veins

Split Azygos Vein: A Case Report

The azygos venous system, which comprises the azygos, hemiazygos, and accessory hemiazygos veins, assists in blood drainage into the superior vena cava (SVC) from the thoracic cage and portions of the posterior mediastinum. Routine dissection of a fresh-frozen cadaveric specimen revealed a split azygos vein. The azygos vein branched off the inferior vena cava (IVC) at the level of the second lumbar vertebra as a single trunk and then split into two tributaries after forming a venous plexus. The right side of this system drained into the SVC and, inferiorly, the collective system drained into the IVC. Variant forms in the venous system, especially the vena cavae, are prone to dilation and tortuosity, leading to an increased likelihood of injury. Knowledge of the anatomical variations of the azygos vein is important for surgeons who use an anterior approach to the spine for diverse procedures.

An Unusual Benign Cause of an Alarming Finding on Chest-X ray: A Case Report of Widened Mediastinum due to Rare Congenital Abnormality (Azygos Vein Continuation of Inferior Vena Cava)

Acute widened mediastinum is an alarming finding. It has many possible differential diagnoses; aortic dissection (AD) is considered one that carries catastrophic outcomes. AD is relatively uncommon; it requires early and accurate diagnosis and treatment for better patient survival. However, acute mediastinal widening also can be present in more benign conditions. We report a case of a 50-year-old African American female with postoperative shortness of breath; initial imaging studies revealed an acute widened mediastinum, but on further management with diuresis and follow-up imaging, she was diagnosed with azygous vein continuation of the Inferior vena cava (IVC). This is considered as a rare benign cause of wide mediastinum. Clinicians must be aware of the presence of such a benign cause when dealing with acute wide mediastinum.

A rare variation of the hemiazygos vein draining into the persistent left superior vena cava

During an educational dissection of a 72-year-old Chinese male cadaver, the hemiazygos vein (HAV) coursing the left side that drains into the persistent left superior vena cava was observed. The HAV was formed at the junction of the 9th to 11th right posterior intercostal veins, right subcostal vein, 5th to 11th left posterior intercostal veins, and left subcostal vein; it then ascended posteriorly to the thoracic aorta. After collecting the accessory hemiazygos vein, it crossed over the aorta and the pedicle of the left lung via the hemiazygos arch, then converged with a communicative branch (vein of Marshall) that emerged from the left brachiocephalic vein to form the persistent left superior vena cava and entered the pericardium at the level of the sixth thoracic vertebra. Upon opening the pericardium of our cadaver, the persistent left superior vena cava was found to drain directly into the significantly dilated coronary sinus at the level of the eighth thoracic vertebra. The azygos vein was formed by the union of the first to eighth right posterior intercostal veins and appeared to be finer and shorter than the HAV. The persistent left superior vena cava might be the result of incomplete degeneration of the left posterior cardinal vein. Knowledge of such variations could be of great value to surgeons placing peripherally inserted central catheters because incorrect placement of the azygos venous system can be detrimental to the patient. In addition, during heart surgery, awareness of such variations may prevent major complications, such as hemorrhage or damage to vascular structures, and possibly also provide new insights and perspectives to cardiovascular surgeries.