Pulmonary Hypertension

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General Information About Pulmonary Hypertension

Pulmonary Hypertension Week at the ATS

What is Pulmonary Hypertension?

Pulmonary arterial hypertension (PAH) is a progressive disease caused by a remodeling of small pulmonary arteries that leads to a progressive increase in pulmonary vascular resistance and right ventricular failure. PAH is associated with significant morbidity and mortality, despite the advent of specific therapies that target pathobiologic pathways implicated in the disease process. PAH is typically diagnosed by right heart catheterization (RHC) and is defined as a mean pulmonary artery pressure greater than 25 mmHg in the absence of elevation of the pulmonary capillary wedge pressure. PAH includes a heterogeneous group of clinical entities sharing similar pathological changes that have been subcategorized as idiopathic PAH (IPAH where the cause is unknown), familial PAH (which represents about 6% of IPAH cases), and pulmonary hypertension associated (APAH) with other diseases such as connective tissue diseases (CTD), portopulmonary hypertension and pulmonary hypertension related to HIV infection, drugs and toxins. There is an updated classification of all pulmonary hypertension syndromes from the 4th World Symposium held at Dana Point, California in 2008.

What are the mechanisms involved in the development of pulmonary hypertension?

The exact mechanisms involved in the pathogenesis of PAH remain vastly unknown but are likely to involve significant alterations in the endothelial cells that line up the inside of the vessels, which understanding has led over the past two decades to targeted therapy for this disease. Several lines of evidence also support a role for autoimmunity in the development of the pulmonary vascular changes, including the presence of circulating autoantibodies, pro-inflammatory cytokines (e.g., IL-1 and IL-6) [8], and association of PAH with auto-immune diseases and CTD such as systemic sclerosis (SSc), systemic lupus erythematosus (SLE), and mixed connective tissue disease.

What are the symptoms and signsof PAH and how is this diagnosed?

The diagnosis of PAH is sometimes difficult for the general practitioner because the symptoms of PAH are nonspecific. They include shortness of breath with exertion, sometimes syncope (loss of consciousness), fatigue, lightheadedness or dizziness with effort, swelling of the ankles and weight gain. On physical examination a cardiac murmur and a loud cardiac sound can suggest the disease. The diagnosis can be further suspected on echocardiography (ultrasound of the heart) which is usually the first screening test when the diagnosis is suspected. However, the diagnosis is firmly established only by right heart catheterization.

Who is at risk?

The great majority of patients with PAH of the idiopathic form are female and relatively young although the disease can affect any age. PAH can also affect newborns and children and used to be fatal in a few months to years after the diagnosis prior to the advent of more recent therapy. Pulmonary hypertension can also affect patients with “associated” diseases (rheumatological diseases such as scleroderma and lupus, sickle cell disease, HIV, and some toxic drugs), chronic respiratory diseases (severe emphysema and COPD), cardiac diseases (congenital shunts, cardiac dysfunction and failure), chronic embolism, and other diseases such as sarcoidosis or disease of metabolism. The leading cause of PAH is most likely related to a parasitic infection (schistosomiasis) which affects millions of individuals throughout the world, particularly in Africa, South America, and China. Individuals living at high altitudes or moving to live at high altitude (for example in the Andes) may also be affected.

How is PAH treated?

PAH should be treated in specialized centers which are spread throughout the USA.

Depending on the stage of the disease and the severity of symptoms, PAH is treated with PAH specific oral, inhaled, subcutaneous, and intravenous drugs. Often more than one drug is required. Other drugs such as diuretics (to remove excess fluid) can be used. Patients should also have dietary counseling which includes mainly avoiding salt intake and excess fluid. Drug efficacy and response to treatment is judged on improvement in patients’ symptoms, functional status (ability to walk), and improved physical findings. Activity, such as regular exercise and pulmonary rehabilitation if needed, is encouraged.

While there has been much progress made in the understanding of this dreadful disease, much is left to be done and, particularly, a definite cure is needed. This will be facilitated by recent improved understanding of the genetics of the disease (with the discovery in 2000) of one of the genes involved in familial PAH (also found in many patients with the sporadic form of the disease) and a better understanding of the mechanisms underlying the development of the syndrome. 

SourcePaul M. Hassoun, MD  ATS Pulmonary Circulation Assembly

SourcePulmonary Hypertension Association(http://www.phassociation.org)

Four Facts About Pulmonary Hypertension
  1. Even with multiple medications available, the average time between PH symptom onset and diagnosis is 2.8 years. This has not changed in the past two decades.

  2. Diagnosing PH is challenging because the symptoms of this rare disease resemblesymptoms of many common diseases such as asthma, COPD, and sleep apnea.

  3. Right-heart catherization is considered the “gold standard” for confirming a PH diagnosis.

  4. Optimal care for PH is collaboration between primary care providers and highly specialized PH-treating professionals.

 (Source: http://www.phassociation.org)