ABSTRACT
Untreated, PPH has a 50 percent, 3-year survival and is almost always ultimately fatal.32 No effective therapies were available until the advent of calcium channel blockers in the 1980s. However, only about 10-20 percent of patients have a sustained response to calcium channel blockers, but many patients in this small subset function well for years to decades.33,34 Intravenous therapy with a prostacyclin formulation, epoprostenol, has markedly improved function and survival in PPH.35,36 Intravenous epoprostenol must be given by continuous pump infusion through a central vein catheter, is technically demanding, has undesirable sideeffects (acute withdrawal syndrome, diarrhea, weight loss, flushing), and costs about $80 000 per year. Although i.v. epoprostenol is the current best therapy for PPH, the 3-year mortality is still about 30 percent.37 Other delivery systems include chronic subcutaneous,38 oral,39 and aerosol prostacyclin40,41 formulations, but i.v. prostacyclin is currently the best studied and most reliable delivery system. Newer effective drugs include endothelin receptor antagonists41,42 and phosphodiesterase 5 inhibitors,43,44 and the search for drugs aimed specifically at pathogenetic abnormalities in PPH is a growing reality, now that some of the signaling mechanisms of PPH are better understood.2,45
Double lung transplantation is possible for some patients with end-stage PPH. Approximately 50 PPH patients per year receive lung or heart-lung transplants, out of a total of 1000 lung or heart-lung transplant operations.46 The problems with transplantation include limited donor availability, difficulty in anticipating the time of decompensation and imminent death, and a poorer outcome than in other diseases treatable with transplantation (emphysema, cystic fibrosis, and interstitial lung disease). Bronchiolitis obliterans results in a 50 percent, 4-year survival after lung transplantation, with a slow linear decline in survival.47
