When the tiny blood vessels in your lungs become thickened, narrowed, blocked or destroyed, it's harder for blood to flow through the lungs. As a result, blood pressure increases in the lungs, a condition called pulmonary hypertension.
Pulmonary hypertension is a type of high blood pressure that affects the arteries in your lungs and the right side of your heart.
In one form of pulmonary hypertension, called pulmonary arterial hypertension (PAH), blood vessels in your lungs are narrowed, blocked or destroyed. The damage slows blood flow through your lungs, and blood pressure in the lung arteries rises. Your heart must work harder to pump blood through your lungs. The extra effort eventually causes your heart muscle to become weak and fail.
In some people, pulmonary hypertension slowly gets worse and can be life-threatening. Although there's no cure for some types of pulmonary hypertension, treatment can help reduce symptoms and improve your quality of life.
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The signs and symptoms of pulmonary hypertension develop slowly. You may not notice them for months or even years. Symptoms get worse as the disease progresses.
Pulmonary hypertension symptoms include:
- Shortness of breath (dyspnea), initially while exercising and eventually while at rest
- Dizziness or fainting spells (syncope)
- Chest pressure or pain
- Swelling (edema) in your ankles, legs and eventually in your abdomen (ascites)
- Bluish color to your lips and skin (cyanosis)
- Racing pulse or heart palpitations
Chambers and valves of the heart
A normal heart has two upper (receiving) and two lower (pumping) chambers. The upper chambers, the right and left atria, receive incoming blood. The lower chambers, the more muscular right and left ventricles, pump blood out of your heart. The heart valves, which keep blood flowing in the right direction, are gates at the chamber openings (for the tricuspid and mitral valves) and exits (for the pulmonary and aortic valves).
Your heart has two upper chambers (atria) and two lower chambers (ventricles). Each time blood passes through your heart, the lower right chamber (right ventricle) pumps blood to your lungs through a large blood vessel (pulmonary artery).
In your lungs, the blood releases carbon dioxide and picks up oxygen. The blood normally flows easily through blood vessels in your lungs (pulmonary arteries, capillaries and veins) to the left side of your heart.
However, changes in the cells that line your pulmonary arteries can cause the walls of the arteries to become stiff, swollen and thick. These changes may slow down or block blood flow through the lungs, causing pulmonary hypertension.
Pulmonary hypertension is classified into five groups, depending on the cause.
Group 1: Pulmonary arterial hypertension (PAH)
- Unknown cause (idiopathic pulmonary arterial hypertension)
- A genetic mutation passed down through families (heritable pulmonary arterial hypertension)
- Use of some prescription diet drugs or illegal drugs such as methamphetamines — and other drugs
- Heart problems present at birth (congenital heart disease)
- Other conditions, such as connective tissue disorders (scleroderma, lupus, others), HIV infection or chronic liver disease (cirrhosis)
Group 2: Pulmonary hypertension caused by left-sided heart disease
- Left-sided heart valve disease, such as mitral valve or aortic valve disease
- Failure of the lower left heart chamber (left ventricle)
Group 3: Pulmonary hypertension caused by lung disease
- Chronic obstructive pulmonary disease (COPD)
- Pulmonary fibrosis, a condition that causes scarring in the tissue between the lungs' air sacs (interstitium)
- Obstructive sleep apnea
- Long-term exposure to high altitudes in people who may be at higher risk of pulmonary hypertension
Group 4: Pulmonary hypertension caused by chronic blood clots
- Chronic blood clots in the lungs (pulmonary emboli)
- Other clotting disorders
Group 5: Pulmonary hypertension triggered by other health conditions
- Blood disorders, including polycythemia vera and essential thrombocythemia
- Inflammatory disorders such as sarcoidosis and vasculitis
- Metabolic disorders, including glycogen storage disease
- Kidney disease
- Tumors pressing against pulmonary arteries
Eisenmenger syndrome and pulmonary hypertension
Eisenmenger syndrome is a type of congenital heart disease that causes pulmonary hypertension. It's most commonly caused by a large hole in your heart between the two lower heart chambers (ventricles), called a ventricular septal defect.
This hole in your heart causes blood to flow incorrectly in your heart. Oxygen-carrying blood (red blood) mixes with oxygen-poor blood (blue blood). The blood then returns to your lungs — instead of going to the rest of your body — increasing the pressure in the pulmonary arteries and causing pulmonary hypertension.
Growing older can increase your risk of developing pulmonary hypertension. The condition is more often diagnosed in people ages 30 to 60. However, idiopathic PAH is more common in younger adults.
Other things that can raise your risk of pulmonary hypertension include:
- A family history of the condition
- Being overweight
- Blood-clotting disorders or a family history of blood clots in the lungs
- Exposure to asbestos
- Genetic disorders, including congenital heart disease
- Living at a high altitude
- Use of certain weight-loss drugs
- Use of illegal drugs such as cocaine
- Use of selective serotonin reuptake inhibitors (SSRIs), used to treat depression and anxiety
Complications of pulmonary hypertension include:
Right-sided heart enlargement and heart failure (cor pulmonale). In cor pulmonale, your heart's right ventricle becomes enlarged and has to pump harder than usual to move blood through narrowed or blocked pulmonary arteries.
At first, the heart tries to compensate by thickening its walls and expanding the chamber of the right ventricle to increase the amount of blood it can hold. But these changes create more strain on the heart, and eventually the right ventricle fails.
- Blood clots. Having pulmonary hypertension makes it more likely you'll develop clots in the small arteries in your lungs, which is dangerous if you already have narrowed or blocked blood vessels.
- Arrhythmia. Pulmonary hypertension can cause irregular heartbeats (arrhythmias), which can lead to a pounding heartbeat (palpitations), dizziness or fainting. Certain arrhythmias can be life-threatening.
- Bleeding in the lungs. Pulmonary hypertension can lead to life-threatening bleeding into the lungs and coughing up blood (hemoptysis).
- Pregnancy complications. Pulmonary hypertension can be life-threatening for a woman and her developing baby.