Congenital Interruption of the Inferior Vena Cava • Ronald L. oan det Hont, M.D., and Aloil R. Htl8tt'eiter, M.D. In the usual form of interruption of the inferior vena cava (IVC), the post-renal IVC continues as the azy1os and hemiazygos vein. We report a patient with com· plete interruption of the IVC in whom no direct COD• tinuity existed between the IVC and the azygos system. Connection between these two systems was via the vertebral plexus and ascending lumbar veins. Associated venous malformations included bilateral azygos veins and anomalous connection of pulmonary and hepatic veins.
describe an infant with congenital complete W einterruption of the inferior vena cava (IVC). The vessel terminated abruptly at the level of the first lumbar vertebra and had no direct continuity with the azygos system. Blood was routed from the IVC posteriorly to the vertebral plexus and the ascending lumbar veins, which continued as a bilateral azygos system to connect to the superior venae cavae on either side. The innominate vein was atretic. There was sequestration of the right lower and middle lobe of the lung. The veins from this site, as well as those from the right lobe of the liver, drained anomalously to the IVC via a long common trunk. The left hepatic vein attached directly to the right atrium. Other cardiovascular anomalies consisted of a sinus venosus atrial septal defect, patent ductus arteriosus, hypoplasia of the left heart, and cardiac dextroposition.
FIGURE 1. Venograms from right common iliac vein, AP (anteroposterior view) and LAT ( lateral projection) . Bilateral azygos systems and ascending lumbar veins filled with contrast. Hypoplastic prerenal segment of IVC, with no direct IVC-azygos connection. Azygos vein commences as continuation of ascending vertebral veins. LAT picture has been retouched. Additional details in Figure 4. Refractory cardiac failure and poor weight gain persisted. At six months a repeated catheterization confirmed the previous findings. The pulmonary artery pressure was lower, and the shunt at the ductus level was now left-to-right. The pulmonary-to-systemic blood flow and vascular resistance ratios were 2.2: 1 and 0.4: 1, respectively. The ductus arteriosus
A 20-day-old girl had respiratory distress and cyanosis (of the lower body). Chest x-ray film showed cardiac dextroposition and radiopacity of the middle and lower lobes of the right lung. Auscultation revealed an accentuated second heart sound, no murmurs, and decreased air entry at the right base. The infant was digitalized. At cardiac catheterization the venous catheter inserted in the right superficial saphenous vein could not be advanced to the right atrium or to either azygos vein, but coursed up the veins draining the middle and lower lobes of the right lung. The pulmonary artery pressures, obtained via the right axillary vein, were greater than those of the aorta. A left-toright shunt was present at the atrial level and a right-to-left shunt at the ductus arteriosus. Angiography showed a sinus venous atrial septal defect with anomalous right pulmonary venosus drainage, a large patent ductus, hypoplasia of the left heart, sequestration of the right middle and lower lobes of the lung, and anomalies of the systemic veins. Because of the high pulmonary vascular resistance, surgery was deferred. •From the Section of Pediatric Cardiology, University of Illinois Medical Center, Chicago. Supported in part by the University of Illinois Foundation Goodenberger Medical Research grant 2-St-39-66-3-14. Reprint requests: Dr. van der Horst, Pediatric Cardiology, 840 South Wood Street, Chicago 60612
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FIGURE 2. Venograms in AP projection. IVC termination (A) at short distance from the catheter tip; (B) both azygos veins are visualized and right pulmonary venous trunk ( PV) courses caudally to connect with IVC below diaphragm. LAz = left azygos vein.
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the IVC termination this vessel received a long vertical pulmonary venous trunk from the middle and lower lobes of the right lung ( Fig 2B). This vessel, in tum, interconnected with a large right hepatic venous trunk and its tributaries (Fig 3B). The latter had no direct connection to the heart. The left hepatic vein drained into the right atrium (Fig 3C). The right adrenal vein also connected to the vertical venous trunk. The ascending posterior vertebral veins connected anteriorly with the lumbar veins, which continued as a bilateral azygos system into the thorax connecting directly to large bilateral superior venae cavae. The left superior vena cava connected to the right atrium by a coronary sinus. There was only a small remnant of the innominate vein attached to the right superior vena cava (Fig 3A) . DISCUSSION
was ligated, but death occurred 24 hours later and was attributed to pulmonary vascular obstruction. At autopsy, the dilated right atrium drained a large coronary sinus ( connected the left superior vena) , a large left hepatic venous trunk, and a normal right superior vena cava; it communicated with the left atrium via a fossa ovalis defect. The dilated main pulmonary artery divided into a large left and a small right branch, which supplied the upper lobe of the right lung only. The right middle and lower lobes were perfused by a vessel arising from the aorta below the diaphragm. The ductus arteriosus was adequately ligated. The small left atrium received one right and two left pulmonary veins. A single spleen was normally positioned. There was severe hypoplasia of the right lower and middle lobes of the lung. The large liver had a dominant left lobe. The right kidney was 1 em higher than the left, and the renal vessels were normal. The left adrenal gland was located normally, and the right was 1.5 em higher than the upper pole of the right kidney just beneath the diaphragmatic insertion. The left ovarian vein drained into the left renal vein and the right into the inferior vena cava. ( IVC). The IVC and tributaries were abnormal ( Fig 1 to 4 ) .The IVC was to the right of the spine, smaller than normal ( Fig 1 ) , and ended abruptly a short distance above the right renal vein at the level of the first lumbar vertebra (Fig 2A). Here, the IVC connected posteriorly with the vertebral plexus and the ascending lumbar veins situated behind the vertebral bodies. These veins were extremely prominent and dilated above and below the IVC termination. Just below
Several reports have described infrahepatic interruption of the IVC with azygos continuation. In none of the previous reports was the IVC completely interrupted.1·8 The IVC develops from five embryologic components. The junction of the common iliac veins is the only remnant of the posterior cardinal system. The postrenal segment caudal to the kidneys is derived from the supracardinal system. Most of the prerenal segment, ie, cephalad to the kidneys, is formed by the subcardinal system. The connection between the supracardinal and subcardinal segments of the IVC is established at the level of the kidneys by the renal segment. The most proximal portion of the prerenal segment, ie, the hepatic segment, originates from within the liver. The azygos veins are formed almost entirely from the supracardinal system, with the exception of the most cephalad component of the azygos arch, which is derived from the posterior cardinal system. In early embryonic life there is direct anatomic continuity between the postrenal IVC and the future azygos veins. The principal blood flow into the azygos system comes from the ascending lumbar veins, which are longitudinal anastomoses of the lumbar intersegmental veins. The azygos system represents the thoracic extension of the ascending lumbar veins and is basically a longitudinal anastomosis of the intercostal veins. There are ample connections between the lumbar-azygos system and the anterior and posterior components of the external vertebral venous plexus via segmental veins. Normally in embryonic life, the hepatic venous system and the right subcardinal veins join to form the hepatosubcardinal junction, ie, the prerenal segment of the IVC. The common variety of an interrupted IVC is failure of fusion of the hepatic and the subcardinal prerenal segments. Associated venous anomalies due to persistence of embryonic channels usually occur. The postrenal IVC remains directly continuous with the azygos or hemiazygos systems. In the present case, not only was the IVC interrupted, but there was no direct connection between it and the azygos system. To our knowledge, this is the first description of this type of anomaly. In addition to failure of development of the normal hepatic veins and caudal extension of the hepatic segment of the IVC,
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CONGENITAL INTERRUPTION OF INFERIOR VENA CAVA 639
FIGuRE 3. Venograms in AP projection. Hypoplastic and atretic innominate vein (IV) connecting to righ~ superior vena cava ( SVC) is shown (A). (B) illustrates right lower pulmonary veins interconnecting with and draining right hepatic vein ( RHV) via venous plexus, forming a common vein draining caudally. C shows catheter advanced from right superior vena cava to right atrium and contrast filling left hepatic vein ( L VH), which connects directly to right atrium.
the connection of the right adrenal vein to the pulmonary vein suggested that the subcardinal segment of the prerenal IVC also failed to develop. The IVC ended abruptly at L 1 above the renal veins, whence it connected with the anterior external vertebral plexus and ascending lumbar veins via large segmental veins. The lumbar veins gave rise at T 11 to the azygos veins. The anterior and posterior vertebral veins were connected through large venous channels. The lack of anatomic continuity between the IVC and the azygos system in our case prevented catheterization of the heart from the IVC. This venous anomaly should also block emboli in the event of lower extremity venous thrombosis. Since there is normal continuity between the posterior renal segment of the IVC and the azygos veins in early embryonic life, the anomaly described has an unclear embryogenesis. The occurrence of severe abnormalities in the development of the right lower and middle lobe pulmonary veins and of the right hepatic veins (these being interconnected) may have interfered with the normal development of the supracardinal system, producing the venous discontinuity.
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FIGURE 4. Artistic conception of venous anomalies in our patient based on angiographic and autopsy findings.
1 Sieb GA. The azygos system of veins in American whites and Negroes including observations of the inferior caval venous system. Am J Phys Anthropol 1934; 19:39-163 2 Abrams HL. The relationship of systemic venous anomalies to the paravertebral veins. Am JR 1958; 80:414-19 3 Chuang VP, MenaCE, Hoskins PA. Congenital anomalies of the inferior vena cava: review of the embryogenesis and presentation of a simplified classification. Br J Radio! 1974; 47:206-13 4 Anderson RC, Adams P, Burke B. Anomalous inferior vena cava with azygos continuation ( infrahepatic interruption of the inferior vena cava). J Pediatr 1961; 59:370-83 5 Campbell M, Deuchar DC. Absent inferior vena cava, symmetrical liver, splenic agenesis, situs inversus and their embryology. Br Heart J 1967; 29:268-75 6 Crenshaw R, Okies JE, Phillips SJ, Bonchek LI, Starr A. Partial anomalous systemic venous return : report of surgical treatment in two cases. J Thorac Cardiovasc Surg 1975; 69:433-36 7 Pacofsky KB, WoHel DA. Azygos continuation of the inferior vena cava. AJR 1971; 113:362-65 8 Hietzman ER. Radiologic appearance of the azygos vein in cardiovascular disease. Circulation 1973; 47 :628-34
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