Primary pulmonary hypertension

In medicine, pulmonary hypertension (PH) or pulmonary artery hypertension (PAH) is an increase in blood pressure in the pulmonary artery or lung vasculature. more...

Depending on the cause, it can be a severe disease with a markedly decreased exercise tolerance and right-sided heart failure. It was first identified by Dr Ernst von Romberg in 1891.

Signs and symptoms

A history usually reveals gradual onset of shortness of breath, fatigue, angina pectoris, syncope (fainting) and peripheral edema.

In order to establish the cause, the physician will generally conduct a thorough medical history and physical examination. A detailed family history is taken to determine whether the disease might be familial.

Diagnosis

Normal pulmonary arterial pressure in a person living at sea level has a mean value of 12-16mmHg. Definite pulmonary hypertension is present when mean pressures at rest exceed 25 mmHg. Although pulmonary arterial pressure can be estimated on the basis of echocardiography, pressure sampling with a Swan-Ganz catheter provides the most definite measurement.

Diagnostic tests generally involve blood tests, electrocardiography, arterial blood gas measurements, X-rays of the chest (generally followed by high-resolution CT scanning). Biopsy of the lung is usually not indicated unless the pulmonary hypertension is thought to be secondary to an underlying intrinsic lung disease. Clinical improvement is often measured in a "six-minute walking test", i.e. the distance a patient can walk in six minutes, and stability and improvements in this measurement correlate with reduced mortality.

Causes and mechanisms

Pulmonary hypertension can be primary (occurring without an obvious cause) or secondary (a result of other disease processes.)

Primary PH

Primary pulmonary hypertension (PPH) is considered a genetic disorder. Certain forms of PPH have been linked to mutations in the BMPR2 gene, which encodes a receptor for bone morphogenic proteins, as well as the 5-HT(2B) gene, which codes for a serotonin receptor. Recently, characteristic proteins of human herpesvirus 8 (also known for causing Kaposi sarcoma) were identified in vascular lesions of PPH patients. However, it is not understood what roles these genes and viral particles play in PPH. PPH has also been associated to the use of appetite suppressants (e.g. Fen-phen). While genetic susceptibility to adverse drug reactions is suspected, the cause of the disease is still largely unknown.

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