Pulmonary arterial hypertension (PAH) is a rare disorder which may lead to right heart failure and ultimately death if untreated. This disorder is a result of smooth muscle hypertrophy and proliferation within the
pulmonary artery (see figure 1). Over time, this proliferation causes an increase in pulmonary vascular
resistance which manifests as increased pulmonary arterial pressure and subsequent right heart strain
Figure reproduced with permission from Gaine S. JAMA 2000;284:3160-3168.
PAH is often defined as a mean pulmonary artery pressure of >25 mmHg at rest with a pulmonary capillary wedge pressure less than 15 mmHg. It is through hemodynamics that many of the effects of PAH on the right heart can be quantified. At the onset of disease, pulmonary vascular resistance may be elevated, however, the right heart is able compensate by increasing forward blood flow, thus increasing pulmonary pressure. Over time as pressure and resistance continues to rise, the right heart begins to enlarge and then fail (see figure 2). When the right ventricle fails, patient’s symptoms progress and patients ultimately succumb to this disease.
Figure adapted from Handoko. Eur Respir Rev. 2010;115:72-82.
Recent epidemiology figures suggest PAH has a prevalence of approximately 15 patients per million within the population. It is a disease that affects all races and all ages. Recent registry information in the US suggests that the majority of patients (nearly 80%) diagnosed with the disease are women and the average age of a diagnosis is approximately 50 years.
The prognosis of patients with PAH was first described in 1987 in a registry comprised of 187 patients with a median survival of 2.8 years. Since that time, new treatment strategies have been developed that have improved the prognosis of patients with PAH by approximately 10% (see figure 3). However, overall survival remains poor. There are several things which may independently predict a worse prognosis; these include a worsened functional class, right heart dysfunction, low cardiac index, and having certain concomitant conditions such as connective tissue disease. As you will learn by utilizing the resources within this website, close observation of patients is required to ensure patients are not getting prognostically worse and drug therapy is either changed or escalated, as appropriate.
Adapted from Humbert M. Circulation 2010;122:156-163.
PAH.tv is a series of educational activities aimed at improving care within the field of PAH. The content on this site has been developed by a steering committee of committed PAH experts in collaboration with Total CME.
Gaine S. JAMA 2000;284:3160-3168.
Humbert M, Sitbon O, Chaouat A, et al. Am J Respir Crit Care Med 2006;173:1023–30.
Badesch D, Raskob G, Elliott G, et al. Chest 2010;137;376-387.
D’Alonzo GE, Barst RJ, Ayres S et al. Ann Intern Med 1991;115:343–349.
Humbert M et al. Circulation 2010;122:156-163.
Thenappan T, Shah S, Rich S et al. Eur Resp J 2010. 4.1079-1087.
McLaughlin VV et al. JACC 2009;53:1573-1619.
McLaughlin VV, et al, Circulation. 2009;119:2250-2294.
Housten-Harris T, 2007, Int. J. Clin. Practice; 61(Suppl. 158):10-18.