Massive haemoptysis caused by congenital absence of a segment of inferior vena cava

Discussion Although anomalies of the inferior vena cava are commonly discovered during imaging for other diseases,'-3 it seems that the anomaly in this patient directly contributed to the pathogenesis of the haemoptysis. The bronchial venous system communicates freely with the pulmonary veins and alveolar capillaries on one side, and with the azygos vein on the other." A direct communication between the systemic venous circulation and the pulmonary circulation is therefore present. This makes the bronchial veins vulnerable to pressure changes in either the systemic venous or pulmonary circulations. These bronchial venous channels are thin walled and non-distensible.5 Physiologically about one third of the blood accumulated in the bronchial venous plexuses is thought to return to the azygos vein, while the remaining blood flow returns to the pulmonary veins.7 Although we did not measure pressure in the azygos vein, we believe that the congenital interruption of the inferior vena cava caused azygos venous hypertension due to the massive increase in the azygos venous flow. As a result of this haemodynamic change the bronchial venous drainage to the azygos vein could become impaired and reversal of bronchial venous flow might occur. Engorgement of the bronchial veins would therefore take place, similar to oesophageal varices in portal hypertension. These engorged, thin walled, relatively non-distensible, submucosal bronchial veins may undergo rupture with manoeuvres associated with increased intrathoracic pressure and this could lead to haemoptysis. On the basis of our experience with this case we suggest that an inferior vena cavogram should be considered as one of the investigations when dealing with massive or recurrent haemoptysis of unknown origin.