Pulmonary Hypertension

Definition

Pulmonary hypertension (PH) refers to high blood pressure isolated to the lungs. Pulmonary pressures are only measured precisely through invasive right heart catheterization, but can be estimated through an echocardiogram (heart ultrasound).  Normal pulmonary pressures are 25 mmHg over 10 mmHg with a mean of 8-20 mmHg.  Pulmonary hypertension occurs when the mean pulmonary artery pressure is greater than or equal to 25 mmHg. 

 

What are the signs and symptoms of pulmonary hypertension?

Many of the symptoms of pulmonary hypertension (PH) are very non-specific including fatigue and shortness of breath. Only when the pulmonary hypertension becomes severe and the right heart fails do patients develop more recognizable symptoms of exertional chest pain and exertional syncope (fainting) and signs of right heart failure including hepatic or liver enlargement and peripheral edema.

 

How is PH classified?

Pulmonary hypertension is classified into 5 groups.  Group 1 (PAH): this is called pulmonary arterial hypertension. Criteria to diagnose PAH includes: (1). Mean pulmonary artery pressure greater than or equal to 25 mmHg. (2). Mean pulmonary capillary wedge pressure less than 15 (this excludes the patients in group 2 listed below).  (3). Chronic lung disease and hypoxemia must be absent (this excludes the patients in group 3 listed below).  (4). Venous thromboembolism is absent (this excludes the patients in group 4 listed below).  (5). Miscellaneous disorders including hematological disorders (myeloproliferative diseases and Sickle cell anemia), systemic disorders and metabolic disorders (this excludes those patients in group 5 listed below).

 

Causes include:

Idiopathic PAH, HIV associated PAH, pulmonary vascular disease of scleroderma, pulmonary veno-occlusive disease, PAH associated with portal hypertension (liver disease).
Group 2 – This is pulmonary hypertension (PH) associated with left ventricular or heart disease.
Group 3 –This is pulmonary hypertension (PH) associated with a lung disease and hypoxemia (low blood oxygen). The lung disease is usually severe.  Sleep apnea would be included in this group.
Group 4 – This is pulmonary hypertension (PH) associated with venous thromboembolic disease or blood clots.
Group 5 – This is pulmonary hypertension (PH) associated with hematologic disorders, certain systemic disorders and certain metabolic disorders.

 

What studies are needed if PH is discovered?

The patient must first be placed in the appropriate classification group discussed above. A pulmonologist usually performs this evaluation and classifies the patient in the appropriate group. Tests to evaluate for heart disease including echocardiograms are often ordered. Further testing of lung disease including pulmonary function studies and sleep studies may also be ordered. Tests to exclude thromboembolic diseases like lung scans or lung CT scans are often necessary. If PAH is suspected, a right heart catheterization is required.  If PAH is confirmed, tests to look for causes including blood tests for scleroderma, test for HIV, liver test are often performed.

 

What is the treatment of PH?

Primary treatment of PH is aimed at treating the underlying cause if possible. This may include medication or surgery for heart disease; medications including oxygen for lung disease; CPAP for sleep apnea; anticoagulation for thromboembolic disease.  Advanced therapy with pulmonary vasodilators is mostly reserved for patients with PAH. These specialized medications include: Prostanoids, phosphodiesterase 5 inhibitors, certain calcium channel blockers and endothelian receptor antagonists. Rarely these medications can also be considered in patients with non-PAH disease (classification 2, 3, 4, and 5 above) if primary therapy cannot alleviate rest symptoms.  These medications should be utilized by MD’s (usually pulmonologists) experienced in their use. Exercise is often recommended for patients with PH to their level of tolerance.