IMPORTANT NOTE: JAAPA CME activities consist of 2 articles. To obtain credit, you must also read
Chronic lymphocytic leukemia: The most common leukemia in adults; the post-test will include questions related to both articles. AAPA Fellow members should complete and submit the post-test on the AAPA Web site by going to
www.aapa.org and searching for keyword
JAAPA post-tests. All others may complete and submit the post-test online at no charge at
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KEY POINTS
■ Pulmonary arterial hypertension (PAH) is defined as a mean pulmonary artery pressure of greater than 25 mm Hg at rest or greater than 30 mm Hg with exercise at the time of right heart catheterization. PAH is rare but fatal.
■ The Dana Point guidelines are used to classify pulmonary hypertension according to the underlying pathophysiology associated with the disease.
■ The evaluation includes a history, physical examination, and initial tests including an echocardiogram with right ventricular systolic pressure measurement, ECG, chest radiograph, and pulmonary function testing. Depending on findings, high resolution chest CT, ventilation-perfusion scanning, and laboratory tests may follow.
■ Prostanoids, endothelin receptor blockers, phosphodiesterase type 5 inhibitors, and L-type calcium channel blockers are used to treat PAH. Lung transplantation may be needed if medical therapy fails.
Pulmonary arterial hypertension (PAH) is a complex disease entity that requires a multidisciplinary approach to diagnosis and management. Defined as a mean pulmonary artery pressure of greater than 25 mm Hg at rest or greater than 30 mm Hg with exercise at the time of right heart catheterization, PAH—formerly known as primary pulmonary hypertension—is a rare but fatal disease. The average time from onset of symptoms to diagnosis is 2.2 years, with a median survival of only 2.8 years after diagnosis without treatment.1 Even when managed aggressively, PAH has a 15% annual mortality rate.2
Until the 1990s, little could be done for those with PAH; but now, early diagnosis and treatment can decrease morbidity and mortality and make a substantial difference in a patient's quality of life. The development of novel treatment modalities in the late 1990s turned this once devastating diagnosis into a manageable condition. After the introduction in 1996 of epoprostenol, the first effective therapy for PAH, research and development into additional therapies and the underlying pathology of PAH began in earnest. Current therapies are geared towards restoring endothelial function and reducing vasoconstriction within the pulmonary arterial system.2
Making the diagnosis remains a challenge, but with a systematic approach, it can be accomplished in the primary care setting. By completing the initial workup, the physician assistant can facilitate diagnosis and guide the initial evaluation at a specialized treatment center. This article reviews the signs and symptoms of PAH and explains how primary care PAs can perform an evaluation that successfully identifies this lethal disease.
PATHOPHYSIOLOGY
Once thought to be a disease of simple vasoconstriction within the pulmonary vasculature, PAH has proven to be a much more complex disease entity (Figure 1). Research has demonstrated that pulmonary arterial hypertension is caused by endothelial dysfunction within the pulmonary arterial system, resulting in vasoconstriction, thrombosis, and mitogenesis.2 The process involves a downregulation of nitric oxide, prostacyclin, and overproduction of endothelin-1.3 Prolonged dysfunction within the pulmonary arterial system leads to the formation of myofibroblasts and extracellular matrix, which develops between the endothelium and internal elastic lamina; in turn, this leads to intimal hyperplasia, medial hypertrophy, adventitial proliferation/fibrosis, and the formation of plexiform lesions, which are found in PAH but not in other types of pulmonary hypertension (PH).2 These lesions are believed to be due to both genetic predisposition and environmental factors such as stress, drugs, toxins, hypoxia, and increased inflammation.4 For the most part, PAH does not involve the airway, bronchial circulation, capillaries, or systemic vasculature.2
CLASSIFICATION OF PH
The first classification system for pulmonary hypertension was proposed in 1973 at the first international conference on primary pulmonary hypertension.5 Subsequently, the Evian-Venice classification was adopted at the second/third world meetings in 1998 and 2003, respectively. Finally, at the fourth world meeting in 2008, the most current classification, known as the Dana Point classification, was adopted. The Dana Point guidelines seek to classify pulmonary hypertension according to the underlying pathophysiology associated with the disease.5