Double vena cava inferior

Double vena cava inferior

823 actas urol esp. 2010;34(9):815–826 Double vena cava inferior Vena cava inferior doble Dear Editor, Retroperitoneal vascular anatomy shows m...

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823

actas urol esp. 2010;34(9):815–826

Double vena cava inferior Vena cava inferior doble

Dear Editor, Retroperitoneal vascular anatomy shows multiple variants because of its complex embryological development. Study of retroperitoneal vascular distribution is important to increase safety of surgery, interventional radiology, and imaging diagnosis of retroperitoneal masses, and for the treatment of thromboembolic disease. We report the case of a 76-year-old male patient who was incidentally diagnosed with a left mesorenal tumor, staged as T1aN0M0. Patient had a history of HBP not previously treated. Patient was asymptomatic, and physical examination and laboratory tests provided no significant findings. An abdominal CT scan showed bilateral duplication of the inferior vena cava, with similar sizes in both sides. The left inferior cava joined two left renal veins, crossed the aorta anteriorly, and joined the right inferior vena cava and the right renal vein, after which it continued as a single vein with the usual characteristics. Patient underwent a left laparoscopic nephrectomy, but dissection difficulties due to the atypical vascular distribution of the left kidney required conversion to open surgery. The postoperative course of the patient

was uneventful. Pathological examination revealed a stage pT1aN0M0, Fuhrman grade 3 clear cell renal adenocarcinoma (fig. 1). Abdominal venous network is the result of a complex process starting in early embryonic development (4th week) from three bilateral primitive venous systems (vitelline, umbilical, and cardinal).1,2 The infrahepatic inferior vena cava (IVC) originates between the 6th and 8th weeks through development and regression of the cardinal venous system, consisting of three pairs of venous axes (listed by order of appearance): posterior cardinal veins, subcardinal veins (anterior to posterior cardinal veins), and supracardinal veins (posterior to posterior cardinal veins). These anastomose to each other, with regression of some segments until the final venous network is formed. Inferior vena cava is formed by different segments of embryonic veins (fig. 2): – – – –

Hepatic: right vitelline vein. Prerenal: right subcardinal vein. Renal: right supracardinal anastomosis. Postrenal: right supracardinal vein.

Renal veins develop from a “renal venous ring” by anastomoses between the subcardinal, posterior cardinal, and supracardinal axes, surrounding the aorta. Embryonic kidneys drain through dorsal branches, which disappear, and through ventral branches which develop. On the right side, such ventral branch, derived from the right sub-supracardinal

Right

Posterior Venous sinus Right vitelline v. Posterior cardinal v. Intersupracardinal

Inferior vena cava

Subcardinal v. Sub-supracardinal Supracardinal v Intersubcardinal Anterior

Figure 1 – CT scan showing the double infrarenal cava and its union crossing the left in front of the aorta.

Posterior intercardinal Left

Figure 2 – Embryological development of the inferior vena cava system from the posterior cardinal, subcardinal, and supracardinal veins and the anastomotic network between them.

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actas urol esp. 2010;34(9):815–826

anastomosis, incorporates into the renal segment of IVC. On the left side, the future left renal vein develops from the left sub-supracardinal anastomosis and the intersubcardinal anastomosis. The retroaortic left renal vein is the result of persistence of the posterior ring segment. There are different anatomical venous variants initially described based on anatomical or surgical dissection studies and currently studied using imaging procedures (CR, MRI): – I VC agenesis: this involves development of alternative venous tracts, such as the azygos-hemiazygos system toward the superior vena cava3. – Transposition of left IVC (0.2%-0.5%): persistence of the left and regression of the right supracardinal vein. This is characterized by the presence of a left IVC which, after joining the left renal vein, crosses the aorta anteriorly, joins the right renal vein and ascends on the right side4. – Unilateral or bilateral IVC duplication (0.2%-3%): development as usual with persistence of the left supracardinal vein. Two veins on the right side or one vein on each side of the aorta may appear. This last variant, the one found in our patient, usually results in two vessels of a similar size which meet through a preaortic bridge, similarly to what occurs in left transposition, and continue as a single right-sided IVC from the renal level5,6. – Circumaortic left renal vein: 8.7%. This is due to persistence of the dorsal branch of left kidney and intersupracardinal anastomosis. – Retroaortic left renal vein: 2.1%. This occurs due to regression of the anterior arch and development of the posterior arch of renal ring. – Retrocaval ureter: usually right-sided, this is caused by failed development of the right supracardinal system with persistence of the right posterior cardinal vein. There are complex anatomical variants resulting from the combination of two or more of the previously described variants and from communication with the azygos system.7,8 Most of these conditions are diagnosed in asymptomatic patients. Although rarely, we may find clinical situations where the presence of these anatomical venous anomalies complicates clinical management of the patient: 1. D  ifficulty for performing the surgical procedure: resection or reconstructive renal surgery, surgery for aortic aneurysm, etc. 2. Diagnostic confusion of para-aortic masses or adenopathies in patients subject to ultrasound or CT with no iodinated contrast or with very early sections before venous filling. 3. Complications in intravascular procedures such as placement of filters to prevent embolism from venous thrombosis. Anatomical variants should always be considered in the event of failed embolism prevention after placement of an IVC filter (IVC duplication). Venous thrombosis in the lower

limbs of young patients, particularly in iliac veins, should alert us to the possibility of anatomical variants of IVC, which appear to cause retrograde stasis.9,10 Study of embryology of retroperitoneal venous network allows for explaining its multiple anatomical variants. The potential existence of atypical veins mandates a detailed study of imaging examinations to improve safety of retroperitoneal surgery.

R efere n ces

1. Moore K, Persaud TVN. The developing human: clinically oriented embryology. 7th ed. Philadelphia: WB Saunders; 2003. 2. Bass JE, Redwine MD, Kramer LA, Huynh PT, Harris JH. Spectrum of congenital anomalies of the inferior vena cava: cross-sectional imaging findings. Radiographics. 2000;20:63952. 3. Artico M, Lorenzini D, Mancini P, Gobbi P, Carloia S, David V. Radiological evidence of anatomical variation of the inferior vena cava: report of two cases. Surg Radiol Anat. 2004;26:153-6. 4. Pascual Mateo C, Luján Galán M, Rodríguez García N, Gómez de Vicente JM, Santos Arrontes D, Aguilar E, et al. Vena cava renal izquierda en un paciente con carcinoma de células renales. Actas Urol Esp. 2005;29:693-5. 5. Ongoïba N, Destrieux C, Desme J, Koumare AK. Abnormal features of the sub renal portion of the inferior vena cava. Morphologie. 2006;90:171-4. 6. Nagashima T, Lee J, Andoh K, Itoh T, Tanohata K, Arai M, et al. Right double inferior vena cava: Report of 5 cases and literature review. J Comput Assist Tomogr. 2006;30:642-5. 7. Morita S, Higuchi M, Saito N, Mitsuhashi N. Pelvic venous variations in patients with congenital inferior vena cava anomalies: classification with computed tomography. Acta Radiol. 2007;48:974-9. 8. Minniti S, Visentini S, Procacci C. Congenital anomalies of the venae cavae: embryological origin, imaging features and report of three new variants. Eur Radiol. 2002;12:2040-55. 9. García-Fuster MJ, Corner MJ, Flor-Lorente B, Soler J, Campos S. Anomalías de la vena cava y trombosis venosa profunda. Rev Esp Cardiol. 2006;59:171-5. 10. Nanda S, Bhatt SP, Turki MA. Inferior vena cava anomalies-a common cause of DVT and PE commonly not diagnosed. Am J Med Sci. 2008;335:409-10.

A.M. Castro-Iglesiasa,*, J. Díaz-Bermúdeza, C. Gago-Ferreiroa and A. Noya-Castrob aServicio

de Urología, Hospital Montecelo, Complexo Hospitalario de Pontevedra, Pontevedra, Spain bServicio de Urología, Hospital Montecelo, Complexo Hospitalario de Pontevedra, Pontevedra, Spain *Corresponding author. E-mail: [email protected] (A.M. Castro-Iglesias).