Συντάχθηκε από:
Αναστάσιος Λιάτας, MD, F.I.C.A. – Διευθυντής Χειρουργός
A C Liatas, MD, F.I.C.A. – Consultant Surgeon
Athens General Hospital » EVAGELISMOS «
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Introduction
The development of the IVC involves fusion, regression, and establishment of midline anastomoses between parts of three paired fetal venous systems: the two posterior cardinal veins, the two subcardinal, and two supracardinal νeins. The changes in the abdominal venous systems that produce the final IVC cover a long period from day 25 to day 50, mainly between days 29 and 41. Depending on the embryonic origin, four parts of the IVC have been recognized: (1) hepatic segment, (2) prerenal segment, (3) renal segment and, (4) postrenal segment. “Absent IVC” normally designates absence of the prerenal segment of the IVC only, with azygos continuation being the most common variety of an interrupted IVC. “Full IVC agenesis” should cover those cases in which all four parts of the IVC and the iliac venous system are absent and blood return is accomplished by one or both of the following pathways: (1) vertebrolumbar pathway (anterior external vertebral plexus, ascending lumbar veins, and azygos and hemiazygos veins), and (2) superficial anterior abdominal wall collaterals. This definition is exemplified by the present case and other ones previously reported. “Full IVC agenesis,” an extremely rare condition, may be compatible with normal adolescence, and such a congenital abnormality has never to our knowledge caused acute abdominal symptoms.
Absence of the entire inferior vena cava caused acute abdominal symptoms, and the patient, a twenty-year-old man, was operated on on an emergency basis. Subsequent ascending venography, abdominal computed tomographic scan, intraarterial digital subtraction angiography, and intra-osseous phlebography revealed full inferior vena cava and iliac venous system agenesis, up to and above the level of the hepatic veins, venous return from the lower limbs and the abdominal viscera being through a series of multiple collateral channels and the azygos-hemiazygos system.
Keywords
Inferior vena cava, full inferior vena cava agenesis, vena cava, agenesis of IVC, full agenesis of IVC, congenital anomalies of IVC, thrombosis of IVC
Discussion
There are at present no known therapeutic measures for this very rare anomaly. In pure IVC agenesis disclosed accidentally (eg, by chest x-ray), those cases revealed during investigation of patients with congenital heart abnormalities, and those in symptomatic patients, the management should be focused on the prevention of complications, such as thromboses in the distal drainage channels.
On the other hand, knowledge of this condition is important for surgeons to avoid ligation of the azygos vein in the course of pulmonary or cardiac operation because prevention of the only major route of venous drainage from below the diaphragm may result in death. In complicated cases, eg, hypertension due to a hypoplastic kidney, or ureteric obstruction from constricting venous collaterals as in the present case, surgery is unavoidable. When thrombosis occurs, a life-threatening condition for this type of patient, vigorous anticoagulant treatment has to be instituted promptly that will last until sufficient venous return has been reestablished.
In making the differential diagnosis the following conditions should be taken into account:
- Pathological mediastinal lesions and other vascular anomalies, when the IVC agenesis presents as a mediastinal abnormality on the chest radiograph, to avoid mediastinoscopy or thoracotomy
- Causes of dilatation of the azygos-hemiazygos venous system
- The syndrome of obstruction of IVC in childhood
- Abdominal wall venous collaterals and varicose veins because excision of these veins would interrupt a vital venous return or at least result in intractable ulcers
- Retroperitoneal and para-aortic space-occupying structures
- Causes of difficulty or prevention of catheterization of the heart from the IVC
- Other causes of acute abdominal symptoms (although it should be last in the list)
- Causes of ureteric obstruction
- Causes of retroperitoneal hemorrhage
- Causes of lower back pain
- Causes of Klippel-Trenaunay syndrome
The prognosis of this rare congenital anomaly seems to be directly related to the presence of thrombosis in the retroperitoneal venous collaterals and to any coexistent congenital anomalies (cardiac and vascular defects, situs inversus). In “full IVC agenesis” thrombosis is the major cause of mortality and morbidity (paresthesias of lower legs and lower back pain on exertion, retroperitoneal hemorrhage, hypertension, ureteric obstruction, and emotional distress due to dilated superficial abdominal wall veins). Apart from this anomaly per se, implicating factors favoring thrombosis in this category of patients have been reported such as (1) oral contraceptives and cigarette smoking; (2) increased intraabdominal pressure (constipation, tumors, pregnancy), and (3) dehydration, marasmus, sepsis, and exertion. Therefore, prevention of thrombosis must be our mainstay in helping these patients.
Δημοσίευση Άρθρου
Το πλήρες άρθρο έχει δημοσιευτεί στο: [ Vascular Surgery, Vol. 27, No 2, March 1993; pp: 155-162 ]
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20 Οκτωβρίου, 2012
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