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Elijah Gray
Elijah Gray

Accessory Hemiazygos Vein REPACK



The accessory hemiazygos vein, also called the superior hemiazygous vein,[1] is a vein on the left side of the vertebral column that generally drains the fourth through eighth intercostal spaces on the left side of the body.[2]




accessory hemiazygos vein



It usually receives the posterior intercostal veins from the 4th, 5th, 6th, 7th, and 8th intercostal spaces between the left superior intercostal vein and highest tributary of the hemiazygos vein;[3] the left bronchial vein sometimes opens into it.


The hemiazygos vein (also known as the inferior hemiazygos vein) arises from the confluence of left lumbar ascending and subcostal veins. It is considered to be a left equivalent of the azygos vein. The hemiazygos vein runs in the posterior mediastinum and drains into the azygos vein at the level of the eighth thoracic vertebra.


The hemiazygos vein arises in the upper abdominal region from the confluence of the left ascending lumbar and subcostal veins. In some cases, the hemiazygos vein can also arise from the left renal vein. It runs superiorly, passing either through the aortic hiatus or left crus of diaphragm, to appear in the thoracic cavity. It continues its course superomedially through the posterior mediastinum, traveling on the left hand side of the thoracic spine. It then courses to the right, crossing the aorta, esophagus and thoracic duct posteriorly. This vein terminates by draining into the azygos vein at the level of the T8 vertebra. Occasionally, the hemiazygos vein can be continued by the accessory hemiazygos vein.


The accessory (or superior) hemiazygos vein forms part of the azygos system and along with the hemiazygos vein, it is partially analogous to the right-sided azygos vein. It drains the left superior hemithorax.


Spelling it "hemiazygous" when referring to the vein is incorrect, regardless of whether British or American English 5. In the context of anatomy, see Terminologia Anatomica, hemiazygos vein is the sole correct spelling.


The accessory hemiazygos vein is formed by the confluence of the middle left posterior intercostal veins. It descends to the left of midline, adjacent to the thoracic vertebrae and crosses posteriorly to the aorta at the level of T7-8 to drain into the azygos vein. It normally anastomoses with the left superior intercostal vein.


Connection between the hemiazygos and the accessory hemiazygos, a rare but normal variant. (a,b) Sagittal CT images of the thorax demonstrate the accessory hemiazygos vein in continuity with the hemiazygos vein forming a single vessel (arrows). The level of communication T8 is shown by the arrow in (b). (c) Axial CT image at the level of T11 (lower arrow in Figure 1a) demonstrates the hemiazygos vein (white arrow).


The diagram illustrates the normal anatomy of the azygos system. The blue represents normal venous anatomy. The yellow lines represent the normal variants. SVC, superior vena cava; RBC, right brachiocephalic vein; LBC, left brachiocephalic vein; AV, azygos vein; HAV, hemiazygos vein; AHAV, accessory hemiazygos vein; NV1, normal variant, the accessory hemiazygos drains into the left brachiocephalic vein; NV2, normal variant, the hemiazygos vein is in continuity with the accessory hemiazygos vein.


The hemiazygos and the accessory hemiazygos are variable in their drainage and anatomy. Usually, the accessory hemiazygos and hemiazygos form common channels posterior to the aorta. In rare instances, 3.6% of the time, the hemiazygos and accessory hemiazygos veins form common channels ventral to the aorta called the interazygos veins [2]. A direct connection of the hemiazygos and accessory hemiazygos is thought to be very rare.


This short communication describes two normal variants of the accessory hemiazygous vein in a 15-year-old female. The article demonstrates that knowledge of the aberrant venous anatomy and the collateral pathway is important for the practising radiologist.


A 36-year-old female with sickle cell disease presented with sickle cell pain crisis. After failure to establish peripheral venous access, an internal jugular central venous catheter (CVC) was placed. Confirmation of internal jugular cannulation was performed with bedside ultrasound. A confirmatory chest X-ray revealed an unusual position of the catheter, taking a course inferiorly, making a loop and remaining on the left side of the mediastinum. A lateral view was done and revealed that the catheter passed inferiorly through the internal jugular vein then posteriorly and inferiorly giving the looped appearance. This is better delineated on a sagittal view CT scan showing the tip of the catheter terminating in the accessory hemiazygos vein. This unusual course is due to a variant of the accessory hemiazygos vein which is connected to the left superior intercostal vein. This creates a lower resistance pathway for the CVC which passes from the internal jugular vein, down the left superior intercostal vein (instead of the left brachiocephalic vein) and into the accessory hemiazygos vein. Discussion: The correct tip placement of an internal jugular CVC terminates in the superior vena cava just above the cardiac silhouette. In 1%-2% of individuals, a connection between the accessory hemiazygos and the left superior intercostal vein is present. Rare cases are discovered incidentally during CVC placement. The diameter of the accessory hemiazygos vein is less than half of that of the superior vena cava. The catheter should not be used as central venous access and removal is recommended. Malpositioning of central catheters is unpredictable but can be easily avoided by using intraprocedural methods to confirm tip position. Such modalities include intracavitary ECG or ultrasound with agitated saline injection as described in the SIC (Safe Insertion of Centrally Inserted Central Catheters) protocol.


The accessory hemiazygos vein (also known as superior hemiazygos vein, Latin: vena hemiazygos accessoria, vena hemiazygos superior) is a blood vessel that runs along the left side of the vertebral column. Both the hemiazygos vein and the accessory hamiazygos vein together serve as the left-sided equivalent of the azygos vein.


The accessory hemiazygos vein is mainly formed by tributaries from the fourth to eighth intercostal spaces on the left side of the thorax. Sometimes the left bronchial veins also contribute to creating this vein. The accessory hemiazygos vein descends on the left side of the vertebral column, crosses the 7th thoracic vertebra (T7) and usually drains in the azygos vein. However, sometimes it flows in the hemiazygos vein. In that case, their common trunk joins the azygos vein.


The azygos vein carries blood from the back of your chest and abdomen to your heart. This vein carries blood upward through your diaphragm and the mediastinum, the space between membranes (pleural sacs) that cover the lungs.


Your azygos vein runs along the right side of your spinal column at the back of your chest. This vein begins where the veins between your spinal bones (lumbar) and subcostal veins come together and enter your chest.


Some people have differences in their veins that they are born with (congenital). These congenital differences can cause the azygos vein to drain directly into the right atrium. It may also drain into the:


Sometimes, changes to the shape of your azygos vein happen because of changes in blood flow due to increased blood pressure or something blocking the vein (obstruction). Your azygos vein may become engorged or enlarged.


The azygos vein may also become damaged due to injury. Cuts (lacerations) or ruptures of your azygos vein can result from car accidents or other hard contacts with your chest, such as a fall or a hard hit during sports.


In addition, injury to your azygos vein can occur during thoracic surgeries (surgeries inside your chest cavity). Complications from implanted devices such as pacemakers can also affect your azygos vein. These changes may cause blood pressure in your azygos vein to become too high or too low.


When injury or damage happens, healthcare providers may use procedures to relieve pressure and allow the vein to drain. Providers may make an incision in your chest (thoracotomy) to help blood drain from the space between your lungs (pleural cavity).


The azygos vein, part of the azygos venous system, helps move blood from your chest and abdomen back to your heart, where it receives oxygen. Your healthcare provider is a great resource for steps you can take to help keep your veins healthy.


The accessory hemiazygos vein (vena azygos minor superior) is a vein on the left side of the vertebral column that generally drains the fifth through eighth intercostal spaces on the left side of the body.


Variation of hemiazygos vein with absence of accessory hemiazygos vein- a dissection study Archana G Kalyankar1, Pravin H Shingare2, Pratima R Kulkarni3 1 Assistant Professor, Department of Anatomy, Govt. Medical College, Aurangabad, India2 Director of Medical Education & Research, Govt Dental College, Mumbai, India3 Assosiate Professor, Department of Anatomy, Govt. Medical College, Aurangabad, India Date of Web Publication23-Jan-2020


During the dissection of this region, we encountered a variation in this system. In this case, we observed that the accessory hemiazygos and hemiazygos veins in the left side passed anterior to the aorta and drained to the azygos vein located on the left side of the vertebral column. Other structures were normal in this area.


The posterior intercostal veins drain the thoracic wall. On the two sides of the thorax, the first posterior intercostal vein directly drains into the brachiocephalic vein. The second and third and occasionally fourth intercostal veins join together to form the superior intercostal vein, which drains into the brachycephalic vein on the left side and into the azygous vein on the right side. 041b061a72


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