Anatomical study on azygos vein retrograde perfusion for spinal cord protection during aortic operation

Objective: To Provide morphologic basis and operation designs for spinal cord protection during aortic operation. Methods: The human azygos venous system, vertebral venous plexus, and the venous drainage of spinal cord in 31 human adult cadaveric specimens were investigated by means of routine dissection. Results: The azygos venous system and related veins were observed.The diameters were as follows: azygos vein 9.2±1.9 mm, hemiazygos vein 5.5±1.2 mm, accessory hemiazygos vein 3.8±0.9 mm, left superior intercostals vein 2.0±0.4 mm, right superior intercostals vein 1.9±0.4 mm, left ascending lumbar vein 2.3±0.5 mm, right ascending lumbar vein 2.2±0.6 mm.According to the distribution patterns of the tributaries of azygos vein and the forms of intercostals venous opening, the azygos venous system might be divided into 4 types.The venous valves with variable forms and dimensions were found in the tributaries of the azygos vein.The distribution ensity of spinal veins were rich, the vascular anastomoses between spinal veins and internal vertebral venous plexus were abundant.By way of spinal radicular veins, they communicated with external vertebral venous plexus and azygos venous system. Conclusion: It is a new and feasible method to retrograde perfusion of the azygos vein for spinal cord protection during aortic operation.