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Za unerwienie i zaopatrywanie w składniki odżywcze ścian klatki piersiowej odpowiada powrózek naczyniowo-nerwowy. W swoim przebiegu charakteryzuje się on układem, w którym to żyła międzyżebrowa jest strukturą najbardziej chronioną. Poniżej żyły znajduje się znacznie bardziej narażona na uszkodzenia tętnica międzyżebrowa, natomiast nerw międzyżebrowy jest strukturą, która jako pierwsza ulega uszkodzeniom w przypadku ran kłutych klatki piersiowej. Pomimo tak nietypowego układu struktur w pęczku, możliwe jest wykorzystanie tej wiedzy w praktyce klinicznej do przeprowadzenia zabiegów takich jak torakocenteza, torakotomia, czy też blokada nerwu międzyżebrowego.

Introduction. Intravascular procedures, including central venous catheterization and placement of cardiac implantable electronic device (CIED) leads, present an opportunity for radiological assessment of the relevant vessels. Obtaining vascular access via left clavipectoral triangle veins may lead to an unintentional catheter/lead insertion into a left brachiocephalic vein (BCV) tributary. This article presents the left-BCV tributaries encountered during CIED implantation procedures and discusses the potential impact of vessel topography on the course of such procedures. Material and methods. Venography records of de novo CIED implantation procedures conducted between 2014 and 2018 were analyzed retrospectively. The indication for these venographies had been the need to determine the cause of difficulties in threading a lead through the venous system. As the title suggests, this paper focuses only on the records illustrating the presence and course of left-BCV tributaries. Results. Out of a total of 315 venographies, we found 12 cases of left-BCV tributaries, including nine left superior intercostal veins (SICVs), two left internal thoracic (mammary) veins (IMVs), and one inferior thyroid vein. Other veins had not been visualized. Conclusions. The left SICV and, less commonly, left IMV were the most commonly visualized left-BCV tributaries in the analyzed imaging records of de novo CIED placement procedures. The anatomical variants of those vessels that drain into the left BCV from below, at the outer or convex wall of the bend in the left BCV, increase the risk of unintentional CIED lead or central venous catheter insertion.

Introduction The azygos system of veins (ASV) is a very variable structure characterized as a communication between the inferior and superior vena cava, having the azygos vein (AV), the hemiazygos vein (HV), and the accessory hemiazygos vein (HAV) as its main components, which are responsible for the mediastinal viscera and for the thoracoabdominal wall drainage. The aim of the present study is to report an anatomical variation found in a male cadaver at the Laboratory of Anatomy of the University Center of UNIFACISA, Campina Grande, PB, Brazil. Case Report In the posterior mediastinum, the union of the HV, of the HAV, and of the 8th left posterior intercostal vein formed a common trunk at the level of the left 8th intercostal space, crossing the mediastinum posterior to the aorta artery, ending up in the AV, in the right hemithorax. Conclusion The study of the anatomical variations of the ASV is important and will provide knowledge for physicians not to confuse them with pathological processes in imaging exams. Moreover, it can provide safety in surgical approaches of the thorax.

Paravertebral and intercostal nerve blocks have experienced a resurgence in popularity. Ultrasound has become the gold standard for visualization of the needle during injection of the analgesic, but the intercostal artery and vein can be difficult to visualize. We investigated the use of spectral analysis of raw radiofrequency (RF) ultrasound signals for identification of the intercostal vessels and six other tissue types in the intercostal and paravertebral spaces. Features derived from the one-dimensional spectrum, two-dimensional spectrum, and cepstrum were used to train four different machine learning algorithms. In addition, the use of the average normalized spectrum as the feature set was compared with the derived feature set. Compared to a support vector machine (SVM) (74.2%), an artificial neural network (ANN) (68.2%), and multinomial analysis (64.1%), a random forest (84.9%) resulted in the most accurate classification. The accuracy using a random forest trained with the first 15 principal components of the average normalized spectrum was 87.0%. These results demonstrate that using a machine learning algorithm with spectral analysis of raw RF ultrasound signals has the potential to provide tissue characterization in intercostal and paravertebral ultrasound.

Knowledge of variations of azygos and hemiazygos veins is of importance to cardiothoracic surgeons and radiologists during various surgical, radiological, and echography techniques. We report some unique variations of azygos system of veins observed during dissection classes for undergraduate medical students. The azygos vein was formed as usual by the union of right subcostal and ascending lumbar veins. The vein ascended upward and to the left to reach the midline at the level of the 9th thoracic vertebra. After ascending till 5th thoracic vertebra, it gradually inclined to the right of midline and terminated by opening into the superior vena cava at the level of the 3rd thoracic vertebra. There was no major variation in the tributaries of the azygos vein on the right side, except that the right superior intercostal vein crossed behind the azygos vein from right to left and opened into the left side of the azygos vein. Further, two anastomotic veins connected the 10th, 11th and 12th posterior intercostal veins with each other to form two anastomotic circles on the right side of 10th to 12th thoracic vertebrae. The hemiazygos vein bifurcated on the left side of the 10th thoracic vertebra and the two ends opened into the azygos vein at the level of 9th and 10th thoracic vertebrae forming a venous circle in front of the 10th thoracic vertebra. The course of accessory hemiazygos vein was noteworthy. Instead of its classic descending course, the vein ascended upward from the left side of the 8th thoracic vertebra till the 6th thoracic vertebra before opening into the azygos vein.

Azygos venous system drains the venous blood from thoracic wall. Knowledge of variations of its course and tributaries is important to cardiothoracic surgeons, radiologists and orthopedic surgeons. We observed the following variations in the azygos veins. Both azygos and hemiazygos veins were formed by union of lumbar azygos and subcostal veins of corresponding sides. The ascending lumbar vein did not drain into the azygos system. The hemiazygos vein had a larger diameter than the lower part of azygos vein and it joined azygos vein at the level of seventh thoracic vertebra. Accessory hemiazygos vein was totally absent. The azygos vein received 4th to 11th right posterior intercostal veins and also received 3rd to 6th left posterior intercostal veins. Hemiazygos vein received 7th to 11th left posterior intercostal veins.

The aim of this study was to describe the possible variations in the connection between the internal venous vertebral system and the cranial vena cava in rabbit using corrosion technique. The study was carried out on 40 adult New Zealand white rabbits. The venous system was injected by using Batson's corrosion casting kit number 17. We found the connection between the internal venous vertebral system and the cranial vena cava by means of the vertebral veins and the right azygos vein. The vertebral vein was present as independent tributary in 36 cases (90%). In the rest of the cases, it was found as being double, being triple, or forming a common trunk with other veins. The azygos vein was present as independent tributary of the cranial vena cava in 39 cases (97.5%). We found also a common trunk formed by the junction of the deep cervical vein, the right vertebral vein, and the azygos vein in one case (2.5%). The azygos vein received 6, 7, 8, or 9 pairs of dorsal intercostal veins. Documenting the anatomical variations in the rabbit will aid in the planning of future experimental studies and determining the clinical relevance on such studies.

Atypical anatomy may be encountered unexpectedly and undiagnosed in clinical practice, and this is especially important during the performance of interventional procedures such as transvenous implantation of cardiac electronic devices. The body of the first rib can be absent. If this not noticed, pneumo-/haemothroax may be induced during subclavian vein puncture as the needle may enter the first intercostal space rather than the costo-clavicular angle. The cephalic vein may pursue a supraclavicular course, the axillary vein may drain into an intercostal vein rather than the axillary vein, and the entire length of the axillary-subclavian-brachio-cephalic vein may be absent. Device implanters should be vigilant about the possibility of these anatomical variations, and be equipped with the knowledge and spectrum of alternative techniques needed to deal with them.

Chylothorax is a rare clinical condition characterized by high triglyceride and low cholesterol levels in milky pleural aspirate. Generally, it occurs through leakage of chyle as result of trauma or malignancy. Chylothorax due to tuberculous lymphadenitis is very rare clinical condition that has only been documented in a few cases. Although precise pathogenesis is not known, enlarged mediastinal and hilar lymph nodes are thought to be associated with opening of collateral anastomosis between thoracic duct and the azygos and intercostal veins by creating pressure on thoracic duct and cisterna chyli. Presently described is case of chylothorax thought to be due to compression from mediastinal tuberculous lymphadenitis, and which had complete remission after antituberculosis treatment.

A n asymptomatic intercostal arteriovenous fistula was suspected because of a faint midthoracic intercostal bruit detected during auscultation in a 3-year-old girl with common cold. There was no history of trauma, iatrogenic therapeutic procedures, or congenital abnormality. Multislice contrast-enhanced computed tomography of the thorax revealed an engorged T8 intercostal artery arising from the thoracic aorta, engorged intercostal vein, and engorged intervertebral vein (Figures 1-3; Figures 1 and 3 available at www.jpeds.com). A three dimensional volume-rendered lateral oblique image confirmed the engorgement of the T8 intercostal artery arising from the thoracic aorta and the engorgement of the intercostal vein (Figure 4; available at www.jpeds.com). Based on the imaging and clinical findings, the diagnosis of congenital intercostal arteriovenous fistula was made. The patient underwent uneventful coil embolization. Intercostal arteriovenous fistulas and malformations are rare lesions, and only a few cases have been published. Most of them occur secondary to trauma or iatrogenic therapeutic procedures and in association with neurofibromatosis type 1, although a congenital origin is suggested in extremely rare cases. Clinical manifestations vary according

A novel technique for chelonian venipunture is described. Angiographic studies using radio-opaque iohexol, static radiography, and video fluoroscopy were undertaken in several chelonian species. Latex injected dissections were also performed to confirm the vascular anatomy. These studies indicate that a clinically useful venipuncture site is present in the anterior dorsal midline at the junction of the common intercostal veins and the caudal cervical branch of the external jugular veins, located just craniad of the last mobile cervical vertebra.

Toracoscopia é o método de visibilização da cavidade torácica através de endoscópio rígido ou flexível, indicado como exame auxiliar para diagnóstico das diversas afecções do tórax. Pode ser realizada com o animal sob anestesia geral ou em posição quadrupedal através de anestesia local associada ou não a sedativos. Neste trabalho, foram utilizados seis eqüinos hígidos, que foram submetidos a toracoscopia, em posição quadrupedal, nos dois hemitórax, com intervalo de 15 dias entre cada procedimento. Durante o exame, pôde-se observar as diversas estruturas da cavidade torácica, tais como: músculo diafragma (porção muscular e tendínea), hiato esofágico, mediastino, aorta, troncos dorsal e ventral do nervo vago, ducto torácico, veia ázigos, veias intercostais, músculos intercostais, costelas, tronco nervoso simpático, tronco vascular toracocervical, traquéia, pulmão (lobo cranial e caudal), esôfago, pericárdio, veia cava caudal, nervo frênico e linfonodos aórticos. Discretas alterações foram observadas ao exame físico, laboratorial e ultra-sonográfico no período pós-operatório, sem que trouxessem prejuízos ao desenvolvimento do experimento e recuperação do animal. A toracoscopia mostrou ser exame de auxílio importante, pela facilidade, rapidez de execução, ampla visibilização da cavidade pleural e trauma mínimo ao paciente. Thoracoscopy is the technique based upon the thoracic cavity visualization by means of rigid or flexible endoscope. It is indicated as an additional diagnostic aid to better define thoracic diseases. It can be performed either in an animal subjected to general anesthesia or in a horse standing on stocks with local anesthesia with or without sedative. Six healthy horses were used in this study they were subjected to thoracoscopy in both hemithorax, standing on stocks, with a 15-day interval between each procedure. It was possible to visualize several thoracic structures through the 13th intercostal space aproach, such as: diaphargma (muscular and tendineous portions), esophageus hiatus, mediastinum, aorta, vagus nerve dorsal and ventral trunk, thoracic ductus, azigus vein, intercostal veins and muscles, ribs, sympathetic nervous trunk, thoracocervical vascular trunk, trachea, lungs (cranial and caudal lobes), esophagus, pericardium, caudal cava vein, phrenicus nerve and aortic linphonodes. Slight alterations were observed in physical, laboratorial and ultra-sonographic exams during pos operative period those alterations did not compromise either this experiment development or the animals well being. By being an easy and fast procedure wich allows pleural cavity broad visualization and pacient minimal trauma, thoracoscopy makes itself a great diagnostic aid exam.

We report the case of a neonate born at 384/7 weeks of gestation with median birth weight and size and in the 75th percentile for head circumference. Routine pregnancy follow up allowed the antenatal discovery of azygos continuation with absence of the inferior vena cava.

A 28-year-old man with a persistent cough and a mild fever was transferred to our institution. Computed tomography angiography showed a giant azygos venous aneurysm associated with the dilation of lumbar veins, azygos veins, hemiazygos veins, and intercostal veins (A-D). At the ages of 3 and 18 years, the man had undergone resection of angiomas in the chest wall (approximately 8 8 7 cm) and on the back (approximately 10 8 8.5 cm), respectively. The pathologic diagnosis showed cavernous hemangioma and lymphangioma. After the second operation, he was subsequently injected with ureaphil every 3 months for 18 times in total. However, the computed tomography scan at that time did not show the visible dilation of azygos veins and fertile varicose veins including intercostal veins, lumbar veins, and partial visceral veins, which was significantly different from that of 10 years later. Azygos venous aneurysms are extremely rare. Nakamura et al reported three main types of azygos venous aneurysms caused by different factors. One of them was dilation of the azygos vein induced by increased venous pressure and volume load, as in the cases of heart failure, portal hypertension, right atrial mural thrombosis, and inferior vena caval occlusion. In this case, we believe it was induced by resection of hemangioma, which increased pressure and volume load. To the best of our knowledge, the giant azygos venous aneurysm caused by resection and embolization of cavernous hemangioma in the chest wall and back has never been reported. Azygos venous aneurysms may also be related to traumatic pseudoaneurysm and idiopathic saccular aneurysm. Its differential diagnosis should include other posterior mediastinal masses. However, Gomez et al reported that if it is thrombosed, surgical therapy is necessary to prevent pulmonary embolism. A video-assisted thoracoscopic excision is recommended as the best technique.

innominate and intercostal veins. PTH gradients assist in localization of parathyroid adenomas. A correlation between surgical pathology and parathyroid venous sampling is made. Conclusion and/or Teaching Points: Parathyroid venous sampling is an effective tool in the evaluation of parathyroid adenoma, particularly in the setting of hyperparathyroidism and negative non-invasive imaging. Interventional radiologists should become familiar with this procedure as it may be a last resort imaging modality.

Spontaneous massive haemothorax is rare. We describe a healthy 44 year old woman who experience sudden onset chest pain while sleeping. Chest radiograph revealed massive right pleural effusion. Progressive dyspnoea, cold sweating, and tachycardia developed later. A tube thoracostomy was performed immediately and massive haemothorax was noted. An emergency thoracotomy was performed because of unstable vital signs. Disruption of the right third intercostal vein with continuous bleeding was observed, and suture ligation of the vein was performed. The total blood loss was about 4000 ml. The patient recovered uneventfully, and her condition at follow up visits to the outpatient department was satisfactory.

Central venous lines are of particular importance in seriously ill children that require parenteral nutrition, chemotherapy, or other medications. The jugular or subclavian veins are ordinarily used for primary access. Alternatives include the femoral veins, the intercostal veins, and transhepatic approaches. If the use of these standard sites of placement is made impossible, due, for example, to chronic thrombosis, an alternative approach has to be found. The following report presents the case of an 11-year-old girl with short-bowel syndrome and a desperate need for parenteral nutrition. Over the course of her treatment, she developed chronic thrombosis of the jugular, subclavian, and femoral veins, as well as thrombosis of the inferior vena cava. As an alternative route for central venous access, we describe a successful direct placement of a tunnelled catheter into the right atrium via a right anterolateral thoracotomy.

Dear Editor, With great interest we read the article by Schroder et al. to be published in a forthcoming issue of the Journal of Gastrointestinal Surgery in which they investigated the potential value of resecting the azygos vein in transthoracic esophagectomy for esophageal cancer. During (robot-assisted) thoracoscopic esophagectomy, the trunk of the azygos vein is often preserved as the scopic ligation of the numerous intercostal veins is technically difficult and time-consuming. One may postulate that this may negatively affect the extent of lymph node harvesting or the circumferential radical (R0) resection rate. Schroder et al. have, therefore, performed a prospective evaluation on the amount of lymph nodes surrounding the azygos vein in 92 patients with esophageal cancer having undergone open transthoracic esophagectomy with two-field lymphadenectomy. Lymph nodes near the azygos vein were identified in 65% of patients and metastases in these lymph nodes were found in 8%. They, therefore, conclude that the dissection of the azygos vein should not be abandoned, irrespective of the surgical approach. A comment should be made on the design of the study. As clearly shown in Figure 2 of their article, they dissected the azygos vein with the surrounding tissues sharply from the esophagus, which is not representative for (robot-assisted) thoracoscopic esophagectomy. In (robot-assisted) thoracoscopic esophagectomy, subsequent to the ligation of the azygos arch, the mediastinal dissection of the esophagus and surrounding tissues is performed sharply along the azygos trunk. In this way, the fatty tissue in between the esophagus and the azygos vein (including the lymph nodes of stations 108 and 110) as well as the thoracic duct are included in the esophageal resected specimen and are not left in situ when the trunk of the azygos vein is preserved. The number of lymph nodes that will be left in situ with (robot-assisted) thoracoscopic esophagectomy will, therefore, be much less than stated in this article. Indeed, in our recently published cadaveric study in which we investigated an identical research question, a mean amount of only 0.67 lymph nodes were identified around the azygos vein using the thoracoscopic dissection method. Using this approach, in 60% of cadavers, no lymph nodes near the azygos vein were detected at all. With regard to the possible effect of azygos vein preservation on the radical resection rate, we can refer to our first report on 21 esophageal cancer patients having undergone robot-assisted thoracoscopic esophagectomy. The R0 resection rate of 76% in that series is similar to that of open transthoracic esophagectomy. In our opinion, it is, therefore, justified to preserve the azygos trunk during (minimally invasive) transthoracic esophagectomy.

Submitted by Guilherme Lemeszenski (guilherme@nead.unesp.br) on 2013-08-22T19:04:07Z No. of bitstreams: 0 Made available in DSpace on 2013-08-22T19:04:07Z (GMT). No. of bitstreams: 0 Previous issue date: 1999-01-01 Made available in DSpace on 2013-09-30T20:06:44Z (GMT). No. of bitstreams: 0 Previous issue date: 1999-01-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T15:17:03Z No. of bitstreams: 0 Made available in DSpace on 2014-05-20T15:17:03Z (GMT). No. of bitstreams: 0 Previous issue date: 1999-01-01 O comportamento da veia ázigos, sua formação e topografia foram estudados em 10 cutias (Dasyprocta aguti, rodentia) adultas (6 machos e 4 fêmeas, capturadas no estado do Piauí, Brasil). Este trabalho tem por objetivo constituir a base de outras investigações, particularmente aquelas referentes à exploração zootécnica desta espécie. O sistema de veia ázigos foi injetado com látex - Neoprene 671, e os animais foram colocados em solução aquosa de formol a 10%, e dissecados. em todas as espécies foi observado que a veia ázigos sempre chega na veia cava cranial em nível do quarto espaço intercostal. A veia ázigos recebe em (50%) dos casos as veias intercostais à direita e (50%) à esquerda. As tributárias da veia ázigos são: as veias frênicas (100%) e a veia bronco esofágica (30%). A veia hemiázigos aparece em todos os casos à esquerda e em 60% dos casos à direita. A veia ázigos comunica-se com a veia hemiázigos esquerda (90%), e com a direita (100%), com a veia cava caudal e veias intervertebrais, com igual freqüência (30%). 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 Piauí, 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%). Universidade Federal do Pauí Universidade Estadual Paulista Faculdade de Odontologia Universidade de São Paulo Faculdade de Medicina Veterinária e Zootecnia Departamento de Cirurgia Universidade Estadual Paulista Faculdade de Odontologia

Pulmonary vein thrombosis is a rare but potentially life threatening complication following lobectomy or bilobectomy. We present a case of right upper pulmonary vein thrombosis after a middle and lower lobectomy diagnosed at transoesophageal echocardiography. The patient was treated with antibiotics and anticoagulation with good recovery. Pulmonary angiography was performed 35 days after surgery and revealed the venous return of the right lung through the intercostal veins. Despite double venous drainage of the lungs consisting of bronchial and pulmonary veins, pulmonary to systemic collaterals following pulmonary vein thrombosis have not previously been reported. The development of this shunt can prevent gangrene, and surgical resection of the lung segment involved can be avoided.

Gastric varices are usually associated with a gastro-renal (G-R) shunt. However, the gastric varices described in this case report were not associated with a G-R shunt. The inflow vessel was the posterior gastric vein and the outflow vessels were the narrow inferior phrenic vein and the dilated cardio-phrenic vein. First, percutaneous transhepatic obliteration of the posterior gastric vein was performed, but the gastric varices remained patent. Then, micro-balloon catheterization of the subphrenic vein was carried out via the jugular vein, pericardial vein and cardio-phrenic vein, however, micro-balloon-occluded inferior phrenic venography followed by micro-coil embolization of the cardio-phrenic vein revealed no delineation of gastric varices resulting in no further treatment. Thereafter, as a gastro-subphrenic-intercostal vein shunt developed, a micro-balloon catheter was advanced to the gastric varices via the intercostal vein and balloon-occluded retrograde transvenous obliteration (BRTO) was performed resulting in the eradication of gastric varices. BRTO for gastric varices via the intercostal vein has not previously been documented.

Sir, Gasparetto et al. [1] present an interesting case report of a rare anomaly—asymptomatic unilateral pulmonary vein atresia that was confirmed by magnetic resonance angiography. Unlike the case reported at our institution [2], the girl had no symptoms and on follow-up after 5 years she remained asymptomatic. An asymptomatic or mildly symptomatic course of this anomaly could be explained by complexity and pliability of the bronchopulmonary circulation. Liebow [3] showed a double venous drainage in normal human lungs consisting of pulmonary and bronchial veins that intercommunicate between each other. Proximal bronchial veins drain into the azygos, hemiazygos and intercostal veins and pulmonary veins drain into the left atrium. Presumably connections between the pulmonary veins and the caval system via azygos veins are capable of expansion or proliferation in various congenital or acquired pathological conditions. Definitive diagnosis and functional parameters of this anomaly require invasive angiography, but because the girl is asymptomatic, postponement of this procedure could be justifiable. We suggest that increasing availability of cross-sectional techniques (CT, MR) with comprehensive three-dimensional visualization will be used more frequently as a first-line modality to clarify incidental findings. Therefore it is possible that this cardiovascular defect will appear to be not so infrequent.

Persistence of a left superior vena cava is a congenital anomaly of considerable interest but by itself exerts no apparent adverse affect on cardiac function. It may occur as an isolated lesion but more often it is associated with many congenital cardiac anomalies. Heretofore it could only be discovered at autopsy or cadaver dissection, but angiocardiography and cardiac catheterization have made possible its recognition during life. This report is a summary of the findings of 11 cases detected by these methods at this center. Embryology In early development, the cephalic portion of the embryo is drained by bilateral symmetrical right and left anterior cardinal veins. These join the posterior cardinal veins near the heart and form the right and left ducts of Cuvier which enter the sinus venosus (Figure 1A). During the eighth week of fetal life, an oblique communication forms between the anterior cardinal veins and shunts blood from the left yein to the right. This vessel becomes the left innominate vein. The development of the left innominate vein is followed by atrophy of the left anterior cardinal vein. It normally persists as the first left intercostal vein. The left duct of Cuvier persists as the oblique vein of the left atrium which enters the coronary sinus. The latter structure is derived from the left half of the sinus venosus. The right duct of Cuvier normally becomes the superior vena cava (Figure 1B). The fully developed superior vena caval system is demonstrated in Figure 2. If the left innominate vein fails to develop, the left anterior cardinal vein persists and continues to drain the left brachiocephalic veins. In this situation it becomes the left superior vena cava. Since the left duct of Cuvier empties into the left half of the sinus venosus which ultimately becomes the coronary sinus, a persistent left superior vena cava drains into this structure (Figure lB).’-3

In fifty-three cats the arterial blood supply to the diaphragm was studied and some observations made on the venous drainage. The arteries arise from the 8th to 13th intercostal arteries, the internal mammary arteries and from branches of the abdominal aorta. Rarely there are direct branches from both the thoracic and the abdominal aorta. There are considerable variations in the pattern of supply. The veins drain into tributaries of the intercostal veins, the internal mammary veins and into the inferior vena cava.

Background The azygos venous system consists of the azygos vein on the right side and the hemiazygos and accessory hemiazygos on the left side. The azygos vein runs through the abdominal cavity along the right side of the vertebral bodies, in a cranial direction, passes through the diaphragm and reaches the mediastinum, where it forms the arch of the azygos which flows into the superior vena cava. Along its course, the azygos vein communicates with the intercostal veins on the right, the hemiazygos vein that collects blood from the left lower intercostal veins, and accessory hemiazygos vein that drains into the left upper intercostal veins. The last two, at the level of the seventh thoracic vertebra, unite and end in the azygos vein. The accessory hemiazygos vein is normally included in the length between T4 and T8. The embryological origin of the accessory hemiazygos vein is the result of an expansion in the direction of the cranial hemiazygos vein, which comes from the left upper sovracardinale vein (Dudiak et al. in Semin Roentgenol 24(1):47–55, 1989; Radiographics 11(2):233–246, 1991; Webb et al. in Am J Roentgenol 139(1):157–161, 1982). Findings This case report describes a rare variant of azygos vein system identified in prenatal diagnosis and confirmed by postnatal ultrasonography. Conclusions The observation of the patient has excluded hemodynamic alterations associated with vascular anomaly.