THROMBOSIS OF THE MAIN PULMONARY ARTERIES

Abstract

The clinical and pathological features of massive thrombosis of the pulmonary arteries have been well documented in recent years but the condition has seldom been recognized during life. In many cases clinical diagnosis is unlikely because the thrombosis is terminal or insidious, in patients already seriously ill with cardiac or pulmonary disease, and merely hastens the end by increasing the load on the right ventricle. However, thrombus may be present in the main pulmonary arteries for a period of weeks or even years, until sudden fresh thrombosis completes the occlusion and proves fatal, so that the condition cannot be considered purely terminal Furthermore, a number of reports have demonstrated that thrombosis of main pulmonary arteries may, on rare occasions, initiate chronic right heart failure, closely resembling chronic cor pulmonale from the more usual causes. Von Juirgensen (1908) described a case showing complete obstruction of the pulmonary trunk with " mainly old firm clot "; he stated that a large portion of the lumen could be " rendered impermeable " without causing death. Experimentally this suggestion was confirmed by the demonstration in dogs that the main pulmonary artery could be compressed gradually until 60 per cent of its lumen was obliterated, without a fall in systemic blood pressure, and that death did not occur until roughly 90 per cent occlusion was reached