High Altitude Pulmonary Hypertension And Chronic Mountain Sickness-Reappraisal Of The Consensus On Chronic And Subacute High Altitude Diseases

An expert consensus workshop group of the International Society for Mountain Medicine recently proposed a new classification of high altitude diseases. Chronic mountain disease or Monge’s disease was defined as a separate entity on the assumption that pulmonary hypertension was not always identified in these patients. This may have to be revised. Healthy high altitude natives living above 3500 m have pulmonary hypertension and right ventricular hypertrophy associated to hypoxemia and polycythemia. There is a direct relation between the level of altitude and the degree of pulmonary hypertension, with exception of Tibetan natives who have the oldest altitude ancestry. After many years of residence at high altitude, some healthy highlanders may lose their adaptation and develop chronic mountain sickness, a clinical entity associated with marked hypoxemia, exaggerated polycythemia and increased pulmonary hypertension, evolving in some cases to heart failure. Other chronic high altitude diseases, such as high altitude heart diseases described in China and high altitude cor pulmonale described in Kyrgystan, have a clinical picture similar to chronic mountain sickness, with lesser degrees of hypoxemia and polycythemia which, however, are often measured at lower levels during the recovery. A systematic review of world-wide literature has demonstrated that pulmonary hypertension is a common feature, in different magnitudes, to healthy highlanders and high altitude diseases. Differences of mean pulmonary artery pression amongst chronic mountain sickness, high altitude heart diseases and high altitude cor pulmonale are no significant and it is highly probable that they are the same disease with different shades. Therefore, chronic high altitude diseases should be integrated in one group and consequently, any scoring system should be applicable to all of them. On the other hand, subacute mountain sickness and high altitude pulmonary edema, clinical entities with a distinct time course, should be considered separately.

Keywords: high altitude diseases; Monge’s disease; pulmonary hypertension; polycythemia; heart failure; cor pulmonale; high altitude pulmonary edema