Congenital anomalies of inferior vena cava and left renal vein: a retrospective study

Congenital anomalies of inferior vena cava and left renal vein: a retrospective study Poster No.: C-2501 Congress: ECR 2015 Type: Scientific Exhibit Authors: M. Tanka, N. Leka, M. Ikonomi, S. Butorac, F. Tuka, E. Rapushi, B. Bega, S. Qamirani; Tirana/AL Keywords: Congenital, Computer Applications-3D, CT-Angiography, CT, Veins / Vena cava, Vascular, Anatomy DOI: 10.1594/ecr2015/C-2501 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. www.myesr.org Page 1 of 22

Aims and objectives Congenital anomalies of the inferior vena cava (IVC) are very rare. These anomalies of the IVC and its tributaries, especially the left renal vein (LRV), have become more commonly recognized in the cross-sectional imaging examinations performed in otherwise healthy individuals. The normal IVC develops between the 6th and 8th week of intrauterine life. Its embryogenesis is a complex process involving the development and regression of 3 sets of paired cardinal veins, namely: the posterior cardinal, the subcardinal, and the supracardinal veins [1]. Anomalies of the IVC derive from aberrations of regression or abnormal persistence of these segments. In addition, due to the complex embryologic relationships of the kidneys and the veins, variations in renal vein anatomy are frequent (in almost 40% of individuals). Multiple right renal veins constitute some of the most commonly recognized anomalies identified by radiologists (28%). In contrast, anomalies in the circumaortic left renal vein are much less common, (constituting 5%-7% of the cases) but represents an area of concern as anomalies are less frequently identified [2]. Recognizing these anomalies of the IVC and the LRV can be a diagnostic challenge for many practitioners. Fortunately, the widespread use of CT scans with 3-dimensional reconstructions during surgical procedures (e.g., preoperative planning for kidney surgery), IR procedures, or other diagnostic reasons, enables timely identification of aberrant anomalies. This technological advance has led to a lower risk of inadvertent damage to anomalous venous structures [3]. To better service our patient population and reduce risk we emphasize the need for established clinical guidelines and practices as it pertains to anatomical education of aberrant vein anomalies and the use of CT technology to avert diagnostic error and other possible implications. With this retrospective study we aim: To determine the frequency of variations of IVC and LRV anatomy in our practice. To accurately evaluate their association with other anatomical anomalies. To compare our findings with those from previous studies. Page 2 of 22

To emphasize the CT-scan findings of such anatomic variations with the intent to prompt the accurate detection of such cases. To point out the importance of these variations in patients' management. Methods and materials Abdominal CT-scan examinations performed over a 6-month period (March-August 2012) were retrospectively reviewed in this single-center study for the incidence and configuration of IVC and LRV variants. Patients were considered eligible if they had undergone contrast enhanced CT scans (CECT) in 3 phases (a hepatic-arterial phase, a portal phase and an equilibrium phase). Cases were excluded from our study, if the IVC and LRV couldn't be evaluated accurately. In accordance with the selection criteria, 400 patients were elected for this study. The usual protocol for CECT in our center constitutes in the administration of 120ml i/v contrast (ultravist with a concentration of 300 mg/dl) at an injection speed of 3.5 and 4 ml/s. This above mentioned protocol was applied in all the reviewed patients, as noted in their imaging report. As our center is made up of two clinics in neighbor cities, all of the selected patients had undergone CT examinations with one of the following equipments: Siemens Somaton Emotion Duo, and Siemens Somaton Emotion 6. We used the most widely accepted classification of IVC anomalies in classifying the anomalies we found (see Table 1 [modified from reference 4]). This classification is based on the embryonic vein from which the anomaly is derived. Table 1. Classification of IVC anomalies (modified) Anomalies of the subcardinal veins Anomalies of supracardinal veins the Persistence of supracardinal Interruption of the IVC with azygos/hemiazygos continuation the left Left inferior vena cava Persistence of both left and Double inferior vena cava right supracardinal veins Anomalies of the renal segment Circumaortic venous ring (circumaortic LRV); Page 3 of 22

Retroaortic renal (retroarotic LRV); vein # Multiple renal veins Anomalies of the postcardinal veins Retrocaval/circumcaval ## ureter # Please note that the multiple renal veins anomaly was not evaluated in our the study, as it constitutes a less diagnostic challenge and as it occurs more often than the other anomalies. ## Not within the objectives of this study. Images for this section: Page 4 of 22

Fig. 7: Axial CT-images of the same patient as in fig 6 showing the inferior left renal vein (white long arrow) crossing posterior to the aorta (note the right renal mass). Page 5 of 22

Results In these series 371/400 patients (92.75 %) had normal IVC and LRV anatomy, while 29/400 patients (7.25 %) showed anatomical variations, from which 7 patients showed IVC variants (24%) and 23 patients (pts) showed LRV variants (79%) as one patient had both azygos continuation of IVC and retroaortic LRV (fig. 2). We detected the following variants (in order of decreasing frequency, percentage included comparing to overall patients): retroaortic LRV - 14 pts (3.5%) which was the most frequent variant, circumaortic LRV - 8 pts (2%), double IVC - 3 pts (0.75%), left IVC - 1 pts (0.5%), azygos continuation of IVC - 2 pts (0.5%). The last group included 2 patients with multiple anomalies: both with polysplenia syndrome; while in one of these patients there was a concomitant celiac trunk anomaly. Table 2 (modified from reference [2]) shows our findings in comparison to findings in other studies. Table 2 (modified from reference [2]), Anatomic Variants of IVC and LRV # (in order of increasing frequency of the IVC and LRV variants as noted in our study) Variant Reported Incidence in the Incidence in our Study Literature [2, 9, 10] Duplicated IVC 1.0 0.75 Left-sided IVC 0.5 0.5 Absent IVC 0.1 None Azygos/hemiazygos 0.5 0.5 Retroaortic left renal vein 3 3.5 Circumaortic left renal vein 7 2 # continuation of the IVC The incidence of the IVC and LRV variations in our study was similar to that reported in the literature, as depicted in table 2. There were only two discrepancies. One was finding Page 6 of 22

an incidence of 2% of circumaortic LRV as compared to 7% reported in the literature [2, 9, 10], and another was finding no patients with absent IVC when compared to 0.1% found in the literature [2, 9, 10]. Future studies may replicate the current literature using a larger number of patients to determine an approximate incidence of this anomaly before concluding a constitutional difference in the study populations compared to other cohorts. No IVC related symptoms were reported in any of the patients. Furthermore, the CT examinations were performed for other unrelated reasons, such as to evaluate the contrast enhancement of suspected organ lesions, or enhancement of the arterial and venous system etc. One example is depicted in figure 4 (fig. 6, 7). Please note that cases of iliac vein thrombosis at an unusually early age in patients with IVC anomalies have been reported in some studies [5, 6]. The embryogenesis of IVC [2, 13, 14] is a complex process which originates between th th the 6 and 8 weeks of intrauterine life and involves a dynamic process of development, regression, anastomosis, and replacement among three longitudinal pairs of veins: postcardinal vein, subcardinal and supracardinal veins (figure 11 below). Fig. 11: 1st diagram - The three sets of paired veins from which IVC and its tributaries develop: in chronologic appearance postcardinal vein (Green), subcardinal vein (Blue) and the supracardinal vein (Pink). 2nd diagram - The left subcardinal veins atrophies and the right subcadinal vein becomes dominant. In a later phase the right subcardinal vein will give rise to the suprarenal part after the anastomosis with the hepatic segment which in turn derives from the vitellin vein. The inferior segment of suprarenal vein Page 7 of 22

forms the infrarenal part of IVC whereas the majority of the postcardinal veins will degenerate except for the distal segments that will become the iliac veins. 3d diagram - The suprarenal, renal and infrarenal segments of the IVC join together to form the complete IVC. References: Modified from reference [1] The posterior cardinal veins appear first and during the course of embryology they atrophy except for the distal segment that becomes the iliac veins. th During the 5 week of intrauterine life the subcardinal veins, which drain the mesonephrons, develop forming multiple anastomosis between subcardinal veins and between postcardinal and subcardinal veins. The anastomosis between the subcardinal veins forms the left renal vein. The left subcardinal vein disappears and the anastomosis between the right suprasubcardinal vein and postsubcardinal vein forms the renal segment of the IVC. th One week later, during the 6 week of intrauterine life, the supracardinal veins are formed. While the left supracardinal vein regresses, the right supracardinal vein becomes the infrarenal portion of IVC. The hepatic segment of the IVC derives from the vitelline vein. While the suprarenal part derives from the anastomosis between the right subcardinal vein and the hepatic segment. All these four segments connect to each other and the normal IVC is complete (fig. 11). An abnormality occurring during this process results in abnormal regression or abnormal persistence of embryonic veins which in turn will give rise to the different variations of IVC. In accordance with the embryology of IVC variants, our CT-scan findings included the following IVC and LRV variants: Double Inferior Vena Cava (fig. 1, 2). Duplicate IVC results when the left supracardinal vein fails to regress. Double IVC can be mistaken with a retroperitoneal mass or paravertebral lymph-node enlargement [3] and lack of knowledge of these variations might result in a misinterpretation of the radiologic images of double IVC, leading to surgical errors such as bleeding during retroperitoneal lymph node dissections. These diagnostic pitfalls can be avoided by performing CECT (venous phase of most importance). Different studies have shown that patients with IVC variations have high risk of developing deep vein thrombosis through an inadequate blood return which increases the blood Page 8 of 22

pressure inside the vein with venous stasis and consequent venous thrombosis in the lower extremities [3, 7]. Treatment of patients with peripheral thromboembolic diseases include double IVC observation, placing filter in either system or coil-embolization of the duplicated segment and placing a filter in the right IVC. Failure to diagnose the double IVC may lead to recurrent embolism in these patients after placement of an IVC filter [3, 9]. Recognition of a double IVC is also important during whole organ transplantation or radical nephrectomy [12]. Our patients with double IVC showed none of the above symptoms or diseases. In such cases, it is generally advised to include the imaging finding in the report and to inform the patient of this anomaly. Azygos continuation of IVC (fig. 3, 4, 5) Failure of the right subcardinal-hepatic anastomosis with resulting atrophy of the right subcardinal vein - results in interruption of the IVC with azygos or hemiazygos continuation. This disorder is often associated with situs anomalies and congenital heart malformations. One of our patients with azygos continuation of IVC besides polysplenia syndrome had concomitant celiac trunk anomaly (see for example fig. 3-5). Ectatic azygos-hemiazygos system may be misdiagnosed as mediastinal, retrocrural and retroperitoneal adenopathies, as well [3, 7]. This anomaly is of great importance when planning a cardiopulmonary bypass and when performing cardiac catheterization [3, 8]. Left-sided Inferior Vena Cava Regression of the right sided supracardinal vein and persistence of the left sided supracardinal vein will give rise to left IVC. Its normal path is similar to that of LRV, which is anterior to the aorta (at the mesoaortic angle) and then follows to the right, receiving the right renal vein. Rarely it may be subjected to a nutcracker-like phenomenon [16] giving rise to clinical symptoms such as abdominal pain, hematuria, proteinuria, varicocele or ureteral/peripelvic varicose veins. It may also be misdiagnosed as paraaortic adenopathy, a retroperitoneal mass lesion or even an aortic aneurysm [11]. Accurate CECT is essential in making the appropriate diagnosis and in planning of adequate strategy for surgeons or interventional radiologists in treating these patients. In our series, only one patient was detected with left sided inferior vena cava. Circumaortic Left Renal Vein (fig. 6, 7, 8) Persistence of the dorsal limb of the embryonic left renal vein and of the dorsal arch of the renal collar (intersupracardinal anastomosis) results in circumaortic LRV. This anomaly has significant clinical importance when planning a nephrectomy; it may also be misdiagnosed as lymphadenopathy [3]. Rarely the posterior left renal vein (the Page 9 of 22

posterior segment of the circumaortic LRV) is compressed by the aorta - giving rise to ## the posterior nutcracker phenomenon. Retroaortic Left Renal Vein (fig. 9, 10) The majority of patients in our study showed this anomaly. It develops from the persistence of the dorsal arch of the renal collar and its clinical importance is related to management of patient's when planning a nephrectomy [12]. Careful attention must be paid not to misdiagnose this anomaly as retroperitoneal lymphadenopathy [3], as well. Rarely the posterior left renal vein may be compressed by the aorta - giving rise to the ## nutcracker phenomenon. ## Posterior Nutcracker phenomenon [15] refers to a compression of the above mentioned vein (posterior LRV), most commonly between the aorta anteriorly and the spine posteriorly, with impaired blood outflow often accompanied by distention of the distal portion of the vein. The nutcracker syndrome (NCS) is a vascular compression disorder constituting the clinical equivalent of the nutcracker phenomenon characterized by a complex of symptoms with substantial variations (see above). It is important to be aware of this abnormality as it can lead to abdominal pain, hematuria, ureteral/peripelvic varicose veins, proteinuria or varicocele. Images for this section: Page 10 of 22

Fig. 1: Double inferior vena cava in a 59 year old man as depicted in diagram A [modified from reference 1], which shows the right and left infrarenal inferior vena cava (IVC), note the left IVC terminating at the left renal vein which crosses the aorta anteriorly. (B) Coronal reconstructed CT-images, the left/double infrarenal IVC (DIVC) draining at the left renal vein, with the right infrarenal IVC on the right of the aorta (Ao) at its normal anatomic location. Fig. 2: Double IVC; axial CT-images of the same patient as in fig 1. Left IVC appears smaller in size compared to the right infrarenal IVC. Page 11 of 22

Fig. 3: Azygos continuation of IVC. Interruption of the suprarenal part of the inferior vena cava (IVC) with azygos continuation in a 50-year-old male, as shown in diagram (black dotted arrow - interrupted IVC). Coronal reconstructed CT-image showing azygos continuation (thin arrow) of IVC. Note also the presence of polisplenia (stars), (thin arrow - vena azygos; thick white arrow - aorta, asteric - IVC) Page 12 of 22

Fig. 4: 3-D reconstrcuted CT-image of the same patient as in fig 8, shows azygos continuation (thin arrow) of IVC, associated with retroaortic left renal vein (dotted white arrow), (thin white arrow - vena azygos; thick white arrow - aorta; asteric - IVC; dotted white arrow - retroaortic LRV) Page 13 of 22

Fig. 5: 3-D reconstrcuted CT-image of the same patient as in fig. 3 & 4, shows a variant of celiac trunk anatomy with the presence of hepatosplenomesenteric trunc (SMA-superior mesenteric artery, splenic artery, hepatic artery and superior gastric artery are depicted). Page 14 of 22

Fig. 6: Circumaortic left renal vein in a 67-year-old female; (A) Diagram showing two left renal veins [modified from reference 1]. (B) Coronal reconstructed CT-images, showing the superior left renal vein (white arrow) crossing anterior to the aorta and the inferior left renal vein (yellow arrow) descending posterior to the aorta in similitude with the diagram (note the right renal mass). Fig. 7: Axial CT-images of the same patient as in fig 6 showing the inferior left renal vein (white long arrow) crossing posterior to the aorta (note the right renal mass). Page 15 of 22

Fig. 8: 3-D reconstructed CT-images in another patient with circumaortic left renal vein (IVC - inferior vena cava; CA LRV - circumaortic left renal vein). Page 16 of 22

Fig. 9: Single retroaortic left renal vein, as shown in the diagram [modified from reference 1]. Axial CT-image in a 48-year-old female shows a single left renal vein (yellow arrow) passing posterior to the aorta. Page 17 of 22

Fig. 10: 3-D reconstructed CT-image in a 70-year-old man showing a single left renal vein descending to cross posterior to the aorta ( Renal A. - renal artery and Retroaortik L.R.V. - retroaortic LRV are shown) Page 18 of 22

Fig. 11: 1st diagram - The three sets of paired veins from which IVC and its tributaries develop: in chronologic appearance postcardinal vein (Green), subcardinal vein (Blue) and the supracardinal vein (Pink). 2nd diagram - The left subcardinal veins atrophies and the right subcadinal vein becomes dominant. In a later phase the right subcardinal vein will give rise to the suprarenal part after the anastomosis with the hepatic segment which in turn derives from the vitellin vein. The inferior segment of suprarenal vein forms the infrarenal part of IVC whereas the majority of the postcardinal veins will degenerate except for the distal segments that will become the iliac veins. 3d diagram - The suprarenal, renal and infrarenal segments of the IVC join together to form the complete IVC. Page 19 of 22

Conclusion Detailed knowledge of the IVC and the LRV variants is of great value in differentiating them from other pathologic conditions and it is crucial in patient's management. Coexistence of such variants with other anomalies was recorded in our study, as in previous similar studies, as we had one patient with azygos continuation of IVC and retroaortic LRV, associated with a variant of celiac trunk anatomy and polysplenia. Awareness of imaging findings in these patients may prevent serious life-threatening complications during retroperitoneal surgery, interventional radiology procedures etc. Therefore, it is important to include in detail such findings in the imaging report. Findings in our study were similar with other previous studies. Personal information Marjeta TANKA, Radiologist - Pediatric Radiologist, Department of Peadiatric Radiology, Mother Teresa UHC; Department of Radiolgy, Hygea Hospital; Professor, Department of Anatomy and Histology; Tirana, Albania Nikollaq LEKA, Radiologists, Department of Radiology, Mother Teresa UHC; Professor, Department of Anatomy and Histology, Mother Teresa UHC; Tirana, Albania Majlinda IKONOMI, Anathomopathologist, Oncologic Service, Department of Pathologic Anatomy and Histology, Mother Teresa UHC; Department of Pathologic Anatomy and Histology, Hygea Hospital; Professor, Department of Pathologic Anatomy and Histology, Mother Teresa UHC; Tirana, Albania Sonja BUTORAC, Radiology Resident, Department of Radiology, Mother Teresa UHC; Radiology Resident, Department of Radiology, National Central Military University Hospital; Tirana, Albania Fjorda TUKA, Radiology Resident, Department of Radiology, Mother Teresa UHC; Tirana, Albania Erinda RAPUSHI, Paediatrics Resident, Department of Paediatrics, Mother Teresa UHC; Tirana, Albania Page 20 of 22

Bajram BEGA, Gastroenterologist, Hepatologist, Department of Gastrohepatology, National Central Military University Hospital, Mother Teresa UHC; Tirana, Albania Sofika QAMIRANI, Professor, Department of Anatomy and Histology, Mother Teresa UHC; Tirana, Albania References 1. Mayo J, Gray R, St Louis E et al., Anomalies of the inferior vena cava, AJR Am J Roentgenol 1983; 140: 339-345. 2. Inferior Vena Cava and Its Tributaries, John Kaufman and Michael Lee, Vascular nd Interventional Radiology, 2 Edition. 3. Bass JE, Redwine MD, Kramer LA et al., Spectrum of congenital anomalies of the inferior vena cava: cross-sectional imaging findings, Radiographics 2000; 20: 639-652. 4. Chuang VP, Mena CE, Hoskins PA: Congenital anomalies of the inferior vena cava. Review of embryogenesis and presentation of a simplified classification. Br J Radiol 1974; 47: 206-213. 5. García-Fuster MJ et al., Inferior Vena Cava Malformations and Deep Venous Thrombosis, Rev Esp Cardiol. 2006;59(2):171-5. 6. Andrea Obernosterer et al., Anomalies of the Inferior Vena Cava in Patients with Iliac Venous Thrombosis, Ann Intern Med. 2002;136(1):37-41. 7. Siegfried MS, Rochester D, Bernstein JR, Milner JW, Diagnosis of inferior vena cava anomalies by computerized tomography, Comput Radiol 1983; 7:119-123. 8. Mazzucco A, Bortolotti U, Stellin G, Galucci V, Anomalies of the systemic venous return: a review, J Card Surg 1990; 5:122-133. 9. Phillips E. Embryology, normal anatomy, and anomalies; In: Ferris EJ, Hipona FA, Kahn PC, Phillips E, Shapiro JH, eds. Venography of the inferior vena cava and its branches; Baltimore, Md:Williams & Wilkins, 1969; 1-32. 10. Ginaldi S, Chuang VP, Wallace S, Absence of hepatic segment of the inferior vena cava with azygous continuation. J Comput Assist Tomogr 1980; 4:112-114. 11. Davachi AA et al., Acute spontaneous rupture of an arteriosclerotic aneurysm into an isolated left sided inferior vena cava, Am J Cardiol 1965; 15:416. Page 21 of 22

12. Anomalies of inferior vena cava and renal veins and implications for renal surgery; Cent European J Urol.2011; 64(1); 4-8. 13. Sadler TW, Langman's Medical Embryology, 9th Ed., Philadelphia, Lippincott Williams &Wilkins. 2004; 261-266. 14. Moore KL and Persaud TV. The cardiovascular system. The Developing Human: Clinically Oriented Embryology, 8th edition, London, Saunders Elsevier.2008; 285-336. 15. Kurklinsky AK et al., Nutcracker Phenomenon and Nutcracker Syndrome, Mayo Clinic Proceedings 2010; 85(6):552-559; doi: 10.4065/mcp. 2009. 0586. 16. Gupta A et al., Mesoaortic entrapment of a left inferior vena cava, The Indian Journal of Radiology&Imaging 2010; 20(1):63-65; doi:10.4103/0971-3026.59758 Page 22 of 22