- Pulmonary arterial hypertension (PAH) is defined as a mean pulmonary artery pressure (mPAP) ≥25 mm Hg at rest with a pulmonary wedge pressure (also known as pulmonary artery occlusion pressure) or left ventricular end-diastolic pressure (LVEDP) ≤15 mm Hg measured by right cardiac catheterization.
- Diagnosis of PAH is growing due to increased awareness and knowledge of the disease state, leading to earlier and improved evaluation and identification.
- Regardless of the etiology, be it unknown or related to an associated medical condition, subgroups of PAH are based on similar clinical and pathologic physiology.
- The underlying cause of PAH is a complicated amalgam of endothelial cell dysfunction, a procoagulant state, platelet activation, vasoconstriction, loss of relaxing factors, cellular proliferation, hypertrophy, fibrosis, and inflammation.
- Patients with PAH present with exertional dyspnea, fatigue, weakness, and exertion intolerance. As the disease progresses, symptoms of right heart dysfunction and failure, such as dyspnea at rest, lower extremity edema, chest pain, and syncope, are seen.
- The only way to make a definitive diagnosis of PAH is by right heart catheterization. The right heart catheterization provides important prognostic information and can be used to assess pulmonary vasoreactivity prior to initiating therapy.
- The goals of treatment are to alleviate symptoms, improve the quality of life, slow the progression of the disease, and improve survival.
- A general goal of PAH treatment is to correct the imbalance between vasoconstriction and vasodilation and prevent adverse thrombotic events to improve oxygenation and quality of life.
- Nonpharmacologic therapy is frequently used to address comorbid conditions that often accompany PAH.
- Conventional therapy of PAH includes oral anticoagulants, diuretics, oxygen, and digoxin.
- Prostacyclin analogs such as epoprostenol, treprostinil, and iloprost induce potent vasodilation of pulmonary vascular beds.
- Endothelin receptor antagonists, bosentan and ambrisentan, improve exercise capacity, hemodynamics, and functional class in PAH.
- Phosphodiesterase-5 inhibitors, including sildenafil and tadalafil, are potent and highly specific drugs that have been shown to reduce mPAP and improve functional class.
- Combination therapy in PAH may address more than one mechanism causing this disease. Combination therapy in clinical trials has provided additional benefit, but more studies are needed.
On completion of the chapter, the reader will be able to:
Discuss the molecular and cellular mechanisms comprising the pathophysiology of pulmonary arterial hypertension (PAH).
Recognize the signs and symptoms associated with the clinical presentation of patients with PAH.
List the diagnostic tests involved in the assessment of patients presenting with PAH.
State the goals of treatment for PAH.
Identify the nonpharmacologic treatments of PAH and their role in therapy.
Identify the conventional therapy of patients with PAH, including the use of oral anticoagulants, diuretics, oxygen, and digoxin.
Compare and contrast the mechanisms of action for the various classes of PAH pharmacotherapy: synthetic prostacyclin and prostacyclin analogs, endothelin receptor antagonists, phosphodiesterase inhibitors, and calcium-channel blockers.
Following evaluation of functional class, hemodynamics, 6-minute walk distance, and other biomarkers, determine appropriate pharmacotherapy for patients with PAH given a treatment algorithm.
Pulmonary hypertension is ...