Azygos Venous System Research Articles

The azygos vein pathway: an overview from anatomical variations to pathological changes.

The azygos venous system represents an accessory venous pathway supplying an important collateral circulation between the superior and inferior vena cava. The aim of this article is to revise the wide spectrum of changes ranging from normal to pathological conditions involving the azygos system. Teaching points • The azygos vein is a collateral venous pathway, becoming a vital shunt if major pathways of venous return are obstructed.• In azygos continuation, the azygos vein becomes significantly enlarged due to inferior vena cava interruption.• Fibrosing mediastinitis is an underestimated acquired disorder.• Fibrosing mediastinitis induces a variable engorgement of collateral veins.• Fibrosing mediastinitis leads to superior vena cava syndrome.

Role of 64-slice multidetector computed tomography in the diagnosis of abnormal vascular connections in congenital heart disease

The aim of this study was to evaluate the role of 64-slice multidetector computed tomography in the diagnosis of abnormal systemic and pulmonary vascular connections and the associated congenital anomalies in comparison to echocardiography. The study enrolled 100 consecutive patients with the provisional diagnosis of congenital heart disease referred for further evaluation by MDCT. Low dose protocol was used for imaging. ECG-gating was used only when coronary anatomy needed to be defined. Ninety-one abnormal vascular connections were found in 73 cases. Abnormal venous connections were further classified into 19 anomalous pulmonary venous connections and 13 anomalous systemic venous connections. Abnormal arterial connections include systemic-systemic connections: 8 coronary artery fistulas, 7 cases of systemic collaterals in aortic coarctation and 2 vascular rings, as well as systemic-pulmonary connections: 38 patent ductus arteriosus (PDA), 4 major aortopulmonary collateral arteries (MAPCAs) and one coronary artery to pulmonary artery fistula. There was significant agreement between echocardiography and MDCT in the diagnosis of partial anomalous pulmonary venous connections (PAPVC) and total anomalous pulmonary venous connections (TAPVC) but not in determining the site drainage, in which MDCT was more accurate. In comparison to MDCT, echocardiography had a sensitivity and specificity of 90.9–95.5% respectively in the diagnosis of PAPVC and 100% and 98.9% in the diagnosis of TAPVC, while only a sensitivity of 45.5% in determining the site of drainage in PAPVC and 75% in TAPVC. However, echocardiography showed all intracardiac defects including that missed by MDCT. The majority of PAPVC were right-sided anomalous veins. Most TAPVC were supracardiac and half were isolated TAPVC. All anomalous systemic venous connections were incidentally discovered by MDCT and were not detected by echocardiography. The left superior vena cava was a component of a duplicated SVC in all cases. The majority of persistent azygos venous system cases were associated with complex CHD. MDCT clearly showed the origin, course and termination of coronary artery fistulas. Echocardiography showed the intracardiac defects in all cases, including that missed by MDCT. Three fistulas originated from the right coronary artery, five from the left coronary artery and one fistula originated from both the right coronary artery and the left circumflex. All coronary-cameral fistulas drained into right cardiac chambers. Less than half were associated with other CHD. Systemic collaterals in coarctation were clearly demonstrated by MDCT, none of which could be visualized by echocardiography. MDCT was not indicated for the diagnosis of PDA but for the associated CHD. Furthermore, MDCT clearly showed MAPCAs with echocardiography being able to detect one case. MDCT provides complete and accurate visualization of extracardiac vasculature but is less reliable for intracardiac defects. It can be used safely in neonates with complex congenital heart disease. It has advantages of non-invasiveness, fast acquisition, high spatial and temporal resolution and three-dimensional reconstruction.

English

Venous anomalies are commonly observed throughout the body during routine dissections or intra-operatively, but a communication between the left renal vein and the ascending lumbar vein has rarely been reported. In this case study a dilated communicating vein was observed connecting the left renal vein with the left ascending lumbar vein. The dilatation may be due to any obstruction in the left renal or inferior vena cava leading to incompetency of the venous valves and retrograde flow of blood causing varicosity in this communicating vein. The rest of the azygos venous system was normal on both sides. Though individuals having this dilated anomalous communication may be asymptomatic, nonetheless awareness regarding this communicating vein is of utmost importance for surgeons performing aorto-iliac and other retroperitoneal surgeries. It may also be confused with other pathologies like para-aortic lymphadenopathy, adrenal pseudo-mass etc. leading to difficulty in radiological diagnosis. Therefore information regarding the presence of this vein is of importance for radiologists and surgeons to avoid pre and post-operative complications.

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

Subjects with persistent left superior vena cava were classified on the basis of the presence and thickness of both superior venae cavae, the anastomotic ramus between the superior venae cavae (anastomotic ramus), and the presence of both azygos veins. Among subjects with persistent left superior vena cava, the percentage of those with weak development of the anastomotic ramus (41.5%) or absence of an anastomotic ramus (35.8%) was 77.3%. In addition, 54.7% of subjects had a left azygos vein. However, 88.7% of subjects had a right azygos vein. In this classification, the most frequently observed types included the presence of both superior venae cavae, an anastomotic ramus, and both azygos veins (20.8%). During student dissection practice sessions performed on 337 cadavers that were carried out from 2002 through 2010, a subject having a left superior vena cava (in 2002) and a subject having both superior venae cavae (in 2003) were detected. The former case was reported previously. The latter case is reported in this paper. The incidence of persistent left superior vena cava was 0.59% (2/337 cadavers).

Congenitally Corrected Transposition of the Great Arteries with Anomalous Inferior Vena Cava Drainage: Multimodality Imaging

Atrioventricular discordance with ventricular-arterial discordance is a rare cardiac anomaly known as congenitally corrected transposition of the great arteries (CCTGA). This malformation has a prevalence of 0.4-0.6% of all congenital heart disease cases. Complete heart block develops in up to 30% of patients with CCTGA. We present the case of a 62-year-old woman diagnosed with CCTGA who, on echocardiography, had anomalous venous drainage where the inferior vena cava (IVC) bypassed the right atrium and drained into the azygos system. Complementary images with magnetic resonance imaging demonstrated the unique anatomical relationship between the IVC, azygos venous system, and the superior vena cava.

Compensatory dilatation of the Azygos Venous system Secondary To Superior Vena Cava Occlusion

Superior vena cava (SVC) occlusion can be clinically recognized in the acute setting when the stenosing process does not allow the development of collateral venous channels, which guarantee the venous drainage to the right heart. On the contrary, when the obstruction develops progressively, the diagnosis of SVC obstruction may remain undiagnosed. In the present case, the presence of SVC thrombosis was purely coincidental. In fact, the obstruction was first noticed on diagnostic tests performed because of the malfunction of a totally implantable Porth a Cath placed into the superior vena cava (through right subclavian access), five years before, in a patient suffering from non-Hodgkin disease. Venography is the most appropriate diagnostic methodology which reveals the presence of a dilated azygos vein as a compensatory mechanism. Comparison with computed tomography allows to confirm the diagnosis and to identify the possible causes. Dilatation of the azygos vein, secondary to superior vena cava thrombosis, although a rare event, should be taken into consideration in those patients with CVC and who present with frequent episodes of deep venous thrombosis.

Anomalous azygos venous system in a south Indian cadaver: a case report.

The posterior thoracic wall, an area drained by the azygos venous system, is a common site for surgical intervention. Since the venous part of the cardiovascular system is subject to most common variation, abnormalities in the azygos venous system are often reported. During routine dissection classes for undergraduate medical students, we encountered a variation in the azygos venous system in a 65 years old south Indian male cadaver. We observed that there was no accessory azygos vein, and left 4th, 5th, 6th and 7th posterior intercostal veins terminated directly into azygos vein. Identifying these types of variations is important during imaging this region and surgical operations of mediastinum.

A Posterior Mediastinal Hematoma Causing Tracheal Obstruction After Internal Jugular Cannulation for Cardiac Surgery

MANY COMPLICATIONS FROM central venous catheterization have been reported after the internal jugular vein approach. The authors report a posterior mediastinal hematoma after coronary artery bypass graft (CABG) surgery, which was assumed to be caused by malpositioning of the internal jugular catheter or guidewire into the azygos venous system.

Anomalous azygos venous system in a south Indian cadaver: a case report

IntroductionThe posterior thoracic wall, an area drained by the azygos venous system, is a common site for surgical intervention. Since the venous part of the cardiovascular system is subject to most common variation, abnormalities in the azygos venous system are often reported.Case presentationDuring routine dissection classes for undergraduate medical students, we encountered a variation in the azygos venous system in a 65 years old south Indian male cadaver. We observed that there was no accessory azygos vein, and left 4th, 5th, 6th and 7th posterior intercostal veins terminated directly into azygos vein.ConclusionIdentifying these types of variations is important during imaging this region and surgical operations of mediastinum.

Off-pump connection of the hepatic to the azygos vein through a lateral thoracotomy for relief of arterio-venous fistulas after a Kawashima procedure

To connect the hepatic veins to the azygos venous system through a lateral thoracotomy, and without the use of extracorporeal circulation, so as to relieve arteriovenous fistulas after a previous Kawashima operation. Description of the operative technique by which the hepatic veins are anastomosed to the hepatic venous system. The surgical approach was successfully applied in 3 patients, all of whom showed an excellent rise of saturations of oxygen after redirection of the hepatic venous blood. The operative method presented is an elegant means of redirecting the hepatic venous blood to the pulmonary circulation without the disadvantages of extracorporeal circulation and resternotomy.

Percutaneous transhepatic obliteration for isolated gastric varices with gastropericardiac shunt: case report

Management of isolated gastric varices with a gastropericardiac shunt (GPS) has not yet been established. We were able to control a case of isolated gastric varices with a GPS by percutaneous transhepatic obliteration (PTO) using a microcatheter. In this case, the main blood drainage route was not a gastrorenal shunt, so transvenous retrograde obliteration could not be performed and PTO using the microcatheter was applied. Percutaneous transhepatic splenic venography revealed that the gastric varices came from the posterior gastric vein and the main drainage route was a GPS. Gastric varices and their blood supply were superselectively embolized using platinum microcoils and absolute ethanol. Portal venous pressure did not change after PTO because the route from the left gastric vein to the azygos venous system was preserved. Computed tomography 7 days after PTO revealed that the gastric varices were completely obliterated by the thrombi. Plasma ammonia level, arterial ketone body ratio, and indocyanine green retention rate at 15 min were improved. We conclude that PTO using a microcatheter is a rational, effective, and safe therapy for isolated gastric varices with a GPS.

Renal cell carcinoma vertebral body metastasis extending into the azygos venous system causing superior vena cava obstruction

We describe a case of superior vena cava (SVC) obstruction caused by extension of tumour thrombus from a vertebral body metastasis through the azygos system to the SVC. The primary tumour was a renal cell carcinoma.

The Origin of the Azygos Venous System, as Deduced from an Anatomical and Radiological Study Employing a Corrosion Technique

The Origin of the Azygos Venous System, as Deduced from an Anatomical and Radiological Study Employing a Corrosion Technique

The origin of the azygos venous system, as deduced from an anatomical and radiological study employing a corrosion technique.

The aim of this study is not only to describe the origin of the human azygos venous system by performing a 3-D reconstruction of a CT scan but also to evaluate the value of the techniques employed in investigating the topographical anatomy of a venous system in the body. Following perfusion with saline to wash away the blood, we injected an ALTUFIX/MINIUM mixture into the azygos vein of a cadaver. The head and trunk were subsequently corroded with hydrochloric acid (HCl). A CT scan of the trunk was obtained both before and after corrosion. According to the spatial resolution of the CT scan, the thinnest identifiable detail was measurable as 0.5 mm. The vertebral lumbar venous system was described, specifying the nomenclature of the lumbar veins (the lumbar veins being designated according to the vertebral body along which they run). On the right side, the lumbar veins at L2 and at L3 formed the lateral root of the azygos vein. On the left side, the vein at L2 formed the reno-azygo-lumbar arch (of Lejars). The lumbar veins, and the origin of the azygos system, were described and compared with previous studies. The 3-D reconstruction showed the importance of veins associated with the posterior paravertebral muscles. This description poses the problem of the metamerisation of the veins, but further evidence is required. Comparisons of the CT scans, 3-D reconstructions, and the ALTUFIX models of the veins obtained from the corrosion technique allowed verification of the 3-D reconstruction and correction of the errors inherent in a computer reconstruction. It is concluded that the description, and understanding, of such a complex system as the vertebral venous system is more valid when the results obtained using different techniques are compared.

Multiple variations of the azygos venous system

Multiple variations of the azygos venous system

A veia ázigos direita na cutia (Dasyprocta aguti, rodentia)

The behaviour of the azygos vein, its formation and topography were studied in 10 cutias (Dasyprocta aguti, rodentia) adults (6 males and 4 females) captured in the State of Piaui, Brazil. This research intends to be a base for other investigations, particularly those with reference to zootechnical exploration of this species. The azygos venous system was injected with latex (Neoprene 671), then the animals were put in watery solution of formol 10%, and dissected. In all specimens it was observed that the azygos vein always arrives in the cranial vena cava on a level with fourth intercostal space. The azygos vein receives more frequently (50%), the intercostal veins on the right side and 5 (50%) on the left one. The tributaries of the azygos vein are the phrenic veins (l00%), and the broncoesophagea vein (30%). The hemiazygos vein is in all cases on the left side and in 60% of the cases on the right side. The azygos vein communicates with the left hemiazygos vein (90%), with the right one (100%), and with the vena cava caudal and intervertebral veins, with equal frequency (30%).

Multiple variations of the azygos venous system.

In a dissection performed in our department, we observed multiple variations of the azygos venous system. The hemiazygos vein was absent. The posterior 8th, 9th, and 10th intercostal veins united and their common trunk crossed the vertebral column obliquely lying anterior to the aorta and posterior to the esophagus and opening into the azygos vein at the level of T7-T8 vertebrae. The 7th left posterior intercostal vein also crossed the column anteriorly and joined the common trunk. The present report identifies the variable positions and courses of the veins related to the azygos system. It is important to keep in mind that different courses of the azygos system do exist, so that extra caution is required during surgery of the mediastinum and also in appropriately interpreting the radiographs.

Azygos blood flow: Phase contrast quantitation in volunteers and patients with portal hypertension pre- and postintrahepatic shunt placement

Flow volume in the azygos venous system was quantitated with Cine-phase contrast (PC) velocity mapping in volunteers and compared with patients with known portal hypertension, who were referred for transjugular intrahepatic portosystemic shunt (TIPS) placement. Subsequently, the TIPS-induced hemodynamic effects on portal and azygos flow were analyzed. To assess intra- and intersubject variability, flow in the azygos veins was measured in each of 10 normal subjects at three different times. Subsequently, portal and azygos flow was quantitated in 20 patients with portal hypertension, before and after TIPS placement. All imaging was performed on a 1.5-tesla magnetic resonance imaging (MRI) system. Azygos flow was measured transaxially at the midthoracic level. Cine-PC flow measurements of the main portal vein followed morphological evaluation of the portal venous system with axial and coronal breath-held magnet resonance angiogram. Azygos flow in normal subjects was characterized by high inter- and low intrasubject variability. Azygos flow in patients with portal hypertension was significantly higher (P < .001). Following successful TIPS placement in 18 patients, Cine-PC revealed a mean decrease in azygos flow of 46.3% (P < .001) and a 134% (P < .001) increase of portal flow. Reflecting the complexity of portal hemodynamics, there was no correlation between the changes in the portal and azygos systems. In 2 patients with early occlusion of TIPS, documented invasively, portal and azygos flow values remained largely unchanged. Cine-PC enables the noninvasive, quantitative assessment of flow within the azygos venous system. Azygos flow was found to be markedly elevated in patients with portal hypertension. Combined portal and azygos PC flow measurements quantitate the therapeutic effect of TIPS placement. (Hepatology 1996 Nov;24(5):1109-15)

Azygos blood flow: phase contrast quantitation in volunteers and patients with portal hypertension pre- and postintrahepatic shunt placement.

Flow volume in the azygos venous system was quantitated with Cine-phase contrast (PC) velocity mapping in volunteers and compared with patients with known portal hypertension, who were referred for transjugular intrahepatic portosystemic shunt (TIPS) placement. Subsequently, the TIPS-induced hemodynamic effects on portal and azygos flow were analyzed. To assess intra- and intersubject variability, flow in the azygos veins was measured in each of 10 normal subjects at three different times. Subsequently, portal and azygos flow was quantitated in 20 patients with portal hypertension, before and after TIPS placement. All imaging was performed on a 1.5-tesla magnetic resonance imaging (MRI) system. Azygos flow was measured transaxially at the midthoracic level. Cine-PC flow measurements of the main portal vein followed morphological evaluation of the portal venous system with axial and coronal breath-held magnet resonance angiogram. Azygos flow in normal subjects was characterized by high inter- and low intrasubject variability. Azygos flow in patients with portal hypertension was significantly higher (P < .001). Following successful TIPS placement in 18 patients, Cine-PC revealed a mean decrease in azygos flow of 46.3% (P < .001) and a 134% (P < .001) increase of portal flow. Reflecting the complexity of portal hemodynamics, there was no correlation between the changes in the portal and azygos systems. In 2 patients with early occlusion of TIPS, documented invasively, portal and azygos flow values remained largely unchanged. Cine-PC enables the noninvasive, quantitative assessment of flow within the azygos venous system. Azygos flow was found to be markedly elevated in patients with portal hypertension. Combined portal and azygos PC flow measurements quantitate the therapeutic effect of TIPS placement.

Rib infarcts in sickling disease

This communication documents the radiographic appearance of multiple rib infarcts that may develop during the course of patients with sickle cell states. It can be associated with and be the cause of the ‘acute chest syndrome’ which has traditionally be attributed, on scanty evidence, to lung infarcts and pneumonia. Bony changes take time to develop but extrapleural changes are readily detected in radiographs. The rib lesions repair leaving residual sclerosis. Sequestra do not develop. The pathogenesis may be due to back pressure in the azygos venous system.