Anomalous Inferior Vena Cava with Azygos Continuation, Dysgenesis of Lung: DISCUSSION

15 May

Previously, an anomalous inferior venacava with azygos continuation, congenital deficiency of the left pericardium, or dysgenesis of the lung was thought to be quite a rare combination of malformations, but owing to recent devel­opments in diagnostic technique, the number of cases diagnosed during life has increased. The incidence of anomalous inferior vena cava was reported to be eight cases out of 800 patients who underwent cardiac catheterization or 0.6 percent of the patients with heart disease. A congenital defect of the pericardium was found in 14,000 or two among 13,000 cases at autopsy. Each of them generally accompanied cardiac and visceral anomalies such as cor biloculare, atrioventricular canal, anomalously connecting pulmonary disease, double-outflow right ventricle, large atrial septal defect, pulmonary stenosis or atresia, or a combination of them, but no case of the triad of an anomalous inferior vena cava with azygos continuation, congenita] deficiency of the left pericardium, and dysgenesis of the lung could be found in the literature.

The inferior vena cava originates from the fusion and alteration of components of several different primitive venous pathways: hepatic, prerenal, renal and postrenal segment. An anomalous inferior vena cava with azygos vein or hemiazygos vein continuation is the result of interruption or failure of fusion of the hepatic vein.

The left duct of Cuvier supplies the blood for the embryonic pleuropericardial membrane which eventually forms the left pericardium. The right duct of Cuvier normally persists as the superior vena cava and thus assures adequate nutrition to the right pleuropericardial membrane. Thus, a defect of the left pericardium accounts for the vast majority of cases.

The critical period for the fusion of the inferior vena cava is known to be the 33rd to 36th embryonal days, and during these days, the embryonic pleuropericardial membrane forms the left pericardium. In the same period, organization of the heart, liver, and spleen, lobulation of the lung, and rotation of the bowel occur. Some unknown teratogenic effect at this critical period might have caused a develop­mental arrest in this case. Moller et al studied children’s congenital cardiac anomalies with polysplenism. These anomalies also were seen in the absence of the hepatic segment of the inferior vena cava and two lobes in each lung with hyparterial bronchi. These investigators considered these anomalies complex to bilateral left-sidedness or levo- isomerism, but our present case was an adult, and the bronchial trees showed a different pattern from bilateral left-sidedness. The abdominal CT scan showed no abnor­malities in the spleen or gallbladder. This might be another type of complex of abnormalities.

It is important for thoracic surgeons to know of the presence of such anomalies, particularly an anomalous inferior vena cava with azygos vein continuation. The diagnosis of these anomalies is not so difficult. Considering these anomalies is important. The chest x-ray film is very useful, and a CT scan is very valuable, as has been previously described.