Pulmonary hypertension is a type of high blood pressure (hypertension) that affects the arteries in the lungs. Some forms of pulmonary hypertension are serious, get progressively worse, and can become fatal. Though pulmonary hypertension cannot be cured, treatment to manage the condition's symptoms can improve a person's quality of life.
Definition & Facts
The heart has two sides, separated by an inner wall (septum). Each side of the heart contains an upper and lower chamber, called the atria and ventricles, respectively. The right ventricle pumps blood to the lungs through a large blood vessel known as the pulmonary artery. The blood deposits carbon dioxide and picks up oxygen in the lungs. The oxygen-rich blood then flows through blood vessels in the lungs (pulmonary capillaries, veins, and arteries) to the left side of the heart.
Blood typically flows very easily through the blood vessels in the lungs. In pulmonary hypertension, changes occur in the lining of the pulmonary arteries that can cause the walls of the arteries to become thick and hard. This makes it difficult for blood to flow through the pulmonary arteries, resulting in pulmonary hypertension.
Symptoms & Complaints
Pulmonary hypertension can also cause shortness of breath. Initially the shortness of breath will only be noticeable during exercise. However, as the condition progresses, a person with pulmonary hypertension will experience shortness of breath while resting. Swelling in the ankles and legs (edema) also occurs with pulmonary hypertension. As the condition progresses, swelling may also be seen in the abdomen.
Pulmonary hypertension can lead to several complications. The right ventricle can become enlarged as it has to pump harder than usual in order to move blood through the pulmonary arteries. Eventually, the right ventricle may fail from the extra strain.
Blood clots are more likely to form in the pulmonary arteries when a person has pulmonary hypertension as well. Additionally, pulmonary hypertension can lead to bleeding in the lungs and coughing blood, which can be fatal. Abnormal heartbeats from the upper or lower chambers of the heart can also occur as a complication of the condition, which can lead to dizziness, heart palpitations, and death.
There are many different possible causes of this condition. Pulmonary arterial hypertension can be caused by a specific genetic mutation that runs in families, congenital heart defects present at birth, exposure to toxins, or by HIV infection, chronic liver disease, or connective tissue disorders, such as lupus and scleroderma.
Pulmonary arterial hypertension can also be caused by certain drugs, such as prescription diet medications and illegal drugs, including methamphetamine. In pulmonary hypertension caused by left-sided heart disease, the cause of the condition is either failure of the left ventricle or left-sided valvular heart disease, which can occur with conditions such as aortic valve disease and mitral valve prolapse.
Pulmonary hypertension can also be caused by chronic blood clots in the lungs and lung disease. Possible causes can include sleep disorders, sleep apnea, pulmonary fibrosis, chronic obstructive pulmonary disease, or long-term exposure to high altitudes for individuals who could be at increased risk of pulmonary hypertension.
Some cases of pulmonary hypertension are associated with other medical conditions, and it is unclear why the pulmonary hypertension occurs. Blood disorders; tumors that press against the pulmonary arteries; Eisenmenger's syndrome; conditions that affect many organs in the body such as sarcoidosis; and metabolic disease such as glycogen storage disease are all associated with pulmonary hypertension.
There are certain risk factors that can put an individual at increased risk of developing pulmonary hypertension. Being overweight, using illegal drugs such as cocaine, a family history of the condition, and taking certain appetite-suppressing medications (anorectics) all put someone at greater risk of developing pulmonary hypertension.
Diagnosis & Tests
Pulmonary hypertension can be challenging to diagnose, especially in its earliest stages because it does not always show up on a physical examination. Even in its later stages, the condition can be challenging to diagnose because the signs and symptoms of pulmonary hypertension are similar to other heart and lung conditions.
A doctor will begin by discussing a patient's medical history and family history and performing a physical examination. A doctor may order one or more tests to confirm a diagnosis of pulmonary hypertension, determine the condition's severity, and to determine the cause of the condition.
A physician may order an echocardiogram to determine how well a patient's right ventricle is functioning as well as to measure the thickness of the right ventricle's walls. In an echocardiogram, sound waves create images of the beating heart.
A physician may also order an exercise echocardiogram to determine how well the heart functions under stress. In this test, a patient undergoes an echocardiogram before and immediately after exercising on a stationary bicycle or treadmill.
An electrocardiogram measures a heart's electrical patterns and can detect abnormal heart rhythms. The test may also be able to determine if the right ventricle is enlarged. Blood tests may be able to show a doctor what is causing a patient's pulmonary hypertension.
A chest X-ray can show an enlarged right ventricle. A chest X-ray may also help identify conditions that may be causing the pulmonary hypertension. A computed tomography (CT) scan can look at the heart's size and function. It can also look for blood clots in the pulmonary arteries. A magnetic resonance imaging (MRI) scan can be performed to check how well the right ventricle is functioning as well as how well blood is flowing through the pulmonary arteries.
A right cardiac catheterization can confirm a diagnosis of pulmonary hypertension and determine the condition's severity. During this test, a cardiologist threads a catheter (a thin tube) into a vein in the neck or groin to the right ventricle and into the pulmonary artery. A doctor can directly measure the blood pressure in the pulmonary artery with this test. Additionally, a doctor can determine what effect specific medications have on the patient's pulmonary hypertension with a right heart catheterization.
A physician may also order a pulmonary function test to measure the airflow in and out of the lungs as well as to determine how much air the lungs can hold. A ventilation/perfusion scan (also called a VQ scan) can determine whether the presence of blood clots is causing pulmonary hypertension. In this test, a tracer is injected into a vein in the arm. The tracer measures air and blood flow to the lungs.
Finally, a physician may order an open-lung biopsy to check for secondary causes of pulmonary hypertension. In an open-lung biopsy, a surgeon removes a sample of lung tissue to look for what may be causing the pulmonary hypertension.
Treatment & Therapy
Pulmonary hypertension cannot be cured. However, there are several medications that can help relieve the condition's symptoms and slow its progress. For instance, vasodilators can be prescribed to open narrow blood vessels in the lungs. Endothelin receptor antagonists reverse the effect of endothelin. Endothelin is a substance found in the walls of blood vessels that causes them to narrow.
High doses of calcium channel blockers may also be beneficial for people with pulmonary hypertension, though few individuals with the condition tend to respond to these medications. Calcium channel blockers help relax the walls of blood vessels. Diuretics can limit fluid buildup in the lungs. Anticoagulants are prescribed to many patients with pulmonary hypertension to reduce the risk of blood clots from developing in the pulmonary arteries.
Sildenafil and tadalafil may also be prescribed, as these drugs open the blood vessels in the lungs, allowing blood to flow more easily. Soluble guanylate cyclase stimulators lower the pressure in the pulmonary arteries. Digoxin is a beneficial medication for pulmonary hypertension patients as well. Digoxin helps the heart pump more blood and beat stronger. The medication can also help control heart rate for individuals who experience abnormal heartbeats.
Oxygen therapy is often beneficial for patients as well, especially those who live at high altitudes or have sleep apnea. Many patients eventually need to use oxygen continuously.
When medication is not effective, surgery may be an option. In an atrial septostomy, a surgeon makes an opening between the upper left and right atria to relieve the pressure on the right side of the heart. This surgery carries serious risks though such as abnormal heartbeats.
Prevention & Prophylaxis
To reduce the risk of coronary heart disease, people can eat a healthy diet and exercise regularly. An individual who is overweight can also reduce his risk of pulmonary hypertension by losing weight.