Question: what are the causes of pulmonary hypertension

Reference:
 Pulmonary Hypertension What Is... Pulmonary hypertension (PULL-mun-ary HI-per-TEN-shun), or PH, is increased pressure in the pulmonary arteries. These arteries carry blood from your heart to your lungs to pick up oxygen. PH causes symptoms such as shortness of breath during routine activity (for example, climbing two flights of stairs), tiredness, chest pain, and a racing heartbeat. As the condition worsens, its symptoms may limit all physical activity. Overview To understand PH, it helps to understand how your heart and lungs work. Your heart has two sides, separated by an inner wall called the septum. Each side of your heart has an upper and lower chamber. The lower right chamber of your heart, the right ventricle (VEN-trih-kul), pumps blood to your pulmonary arteries. The blood then travels to your lungs, where it picks up oxygen. The upper left chamber of your heart, the left atrium (AY-tree-um), receives the oxygen-rich blood from your lungs. The blood is then pumped into the lower left chamber of your heart, the left ventricle. From the left ventricle, the blood is pumped to the rest of your body through an artery called the aorta. For more information about the heart and lungs, go to the Diseases and Conditions Index How the Heart Works and How the Lungs Work articles. PH begins with inflammation and changes in the cells that line your pulmonary arteries. Other factors also can affect the pulmonary arteries and cause PH. For example, the condition may develop if: The walls of the arteries tighten. The walls of the arteries are stiff at birth or become stiff from an overgrowth of cells. Blood clots form in the arteries. These changes make it hard for your heart to push blood through your pulmonary arteries and into your lungs. As a result, the pressure in your arteries rises. Also, because your heart is working harder than normal, your right ventricle becomes strained and weak. Your heart may become so weak that it can't pump enough blood to your lungs. This causes heart failure. Heart failure is the most common cause of death in people who have PH. PH is divided into five groups based on its causes. In all groups, the average pressure in the pulmonary arteries is higher than 25 mmHg at rest or 30 mmHg during physical activity. The pressure in normal pulmonary arteries is 8–20 mmHg at rest. (The mmHg is millimeters of mercury—the units used to measure blood pressure.) Other diseases or conditions, such as heart and lung diseases or blood clots, usually cause PH. Some people inherit the condition (that is, their parents pass the genes for PH on to them). In some cases, the cause isn't known. Outlook PH has no cure. However, research for new treatments is ongoing. The earlier PH is treated, the easier it is to control. Treatments include medicines, procedures, and other therapies. These treatments can relieve PH symptoms and slow the progress of the disease. Lifestyle changes also can help control symptoms. Types The World Health Organization divides pulmonary hypertension (PH) into five groups. These groups are organized based on the cause of the condition. In all groups, the average pressure in the pulmonary arteries is higher than 25 mmHg at rest or 30 mmHg during physical activity. The pressure in normal pulmonary arteries is 8–20 mmHg at rest. (Note that group 1 is called pulmonary arterial hypertension (PAH) and groups 2 through 5 are called pulmonary hypertension. However, together all groups are called pulmonary hypertension.) Group 1 Pulmonary Arterial Hypertension Group 1 PAH includes: PAH that has no known cause. PAH that's inherited (passed from parents to children through genes). PAH that's caused by drugs or toxins, such as street drugs and certain diet medicines. PAH that's caused by conditions such as: - Connective tissue diseases. (Connective tissue helps support all parts of your body, including your skin, eyes, and heart.) - HIV infection. - Liver disease. - Congenital heart disease. This is heart disease that's present at birth. - Sickle cell disease. - Schistosomiasis (SKIS-toe-so-MI-ah-sis). This is an infection caused by a parasite. Schistosomiasis is one of the most common causes of PAH in many parts of the world. Connective tissue diseases. (Connective tissue helps support all parts of your body, including your skin, eyes, and heart.) HIV infection. Liver disease. Congenital heart disease. This is heart disease that's present at birth. Sickle cell disease. Schistosomiasis (SKIS-toe-so-MI-ah-sis). This is an infection caused by a parasite. Schistosomiasis is one of the most common causes of PAH in many parts of the world. PAH that's caused by conditions that affect the veins and small blood vessels of the lungs. Group 2 Pulmonary Hypertension Group 2 includes PH with left heart disease. Conditions that affect the left side of the heart, such as mitral valve disease or long-term high blood pressure, can cause left heart disease and PH. Left heart disease is likely the most common cause of PH. Group 3 Pulmonary Hypertension Group 3 includes PH associated with lung diseases, such as COPD (chronic obstructive pulmonary disease) and interstitial (IN-ter-STISH-al) lung diseases. Interstitial lung diseases cause scarring of the lung tissue. Group 3 also includes PH associated with sleep-related breathing disorders, such as sleep apnea. Group 4 Pulmonary Hypertension Group 4 includes PH caused by blood clots in the lungs or blood clotting disorders. Group 5 Pulmonary Hypertension Group 5 includes PH caused by various other diseases or conditions. Examples include: Blood disorders, such as polycythemia vera (POL-e-si-THE-me-ah VAY-rah or VE-rah) and essential thrombocythemia (THROM-bo-si-THE-me-ah). Systemic disorders, such as sarcoidosis (sar-koy-DO-sis) and vasculitis (vas-kyu-LI-tis). Systemic disorders involve many of the body's organs. Metabolic disorders, such as thyroid disease and glycogen storage disease. (In glycogen storage disease, the body's cells don't use a form of glucose (sugar) properly.) Other conditions, such as tumors that press on the pulmonary arteries and kidney disease. Other Names Group 1 pulmonary arterial hypertension (PAH) that occurs without a known cause often is called primary PAH or idiopathic (id-ee-o-PATH-ick) PAH. Group 1 PAH that occurs with a known cause often is called associated PAH. For example, PAH that occurs in a person who has scleroderma might be called "PAH occurring in association with scleroderma," or simply "scleroderma-associated PAH." Groups 2–5 pulmonary hypertension (PH) sometimes are called secondary PH. Causes Pulmonary hypertension (PH) begins with inflammation and changes in the cells that line your pulmonary arteries. Other factors also can affect the pulmonary arteries and cause PH. For example, the condition may develop if: The walls of the arteries tighten. The walls of the arteries are stiff at birth or become stiff from an overgrowth of cells. Blood clots form in the arteries. These changes make it hard for your heart to push blood through your pulmonary arteries and into your lungs. Thus, the pressure in the arteries rises, causing PH. Many factors can contribute to the process that leads to the different types of PH. Group 1 pulmonary arterial hypertension (PAH) may have no known cause, or the condition may be inherited. ("Inherited" means the condition is passed from parents to children through genes.) Some diseases and conditions also can cause group 1 PAH. Examples include HIV infection, congenital heart disease, and sickle cell disease. Also, the use of street drugs (such as cocaine) and certain diet medicines can lead to PAH. Many diseases and conditions can cause groups 2 through 5 PH (often called secondary PH), including: Mitral valve disease Lung diseases, such as COPD (chronic obstructive pulmonary disease) Sleep apnea Sarcoidosis For more information about the types of PH and the diseases, conditions, and factors that can cause them, go to "Types of Pulmonary Hypertension." Who Is at Risk The exact number of people who have pulmonary hypertension (PH) isn't known. Group 1 pulmonary arterial hypertension (PAH) without a known cause is rare. It affects women more often than men. People who have group 1 PAH tend to be overweight. PH that occurs with another disease or condition is more common. PH usually develops between the ages of 20 and 60, but it can occur at any age. People who are at increased risk for PH include: Those who have a family history of the condition. Those who have certain diseases or conditions, such as heart and lung diseases, liver disease, HIV infection, or blood clots in the pulmonary arteries. (For more information about the diseases, conditions, and factors that cause PH, go to "Types of Pulmonary Hypertension.") Those who use street drugs (such as cocaine) or certain diet medicines. Those who live at high altitudes. Signs & Symptoms Signs and symptoms of pulmonary hypertension (PH) may include: Shortness of breath during routine activity, such as climbing two flights of stairs Tiredness Chest pain A racing heartbeat Pain on the upper right side of the abdomen Decreased appetite As PH worsens, you may find it hard to do any physical activities. At this point, other signs and symptoms may include: Feeling light-headed, especially during physical activity Fainting at times Swelling in your legs and ankles A bluish color on your lips and skin Diagnosis Your doctor will diagnose pulmonary hypertension (PH) based on your medical and family histories, a physical exam, and the results from tests and procedures. PH can develop slowly. In fact, you may have it for years and not know it. This is because the condition has no early signs or symptoms. When symptoms do occur, they're often like those of other heart and lung conditions, such as asthma. This makes PH hard to diagnose. Medical and Family Histories Your doctor may ask about your signs and symptoms and how and when they began. He or she also may ask whether you have other medical conditions that can cause PH. Your doctor will want to know whether you have any family members who have or have had PH. People who have a family history of PH are at higher risk for the condition. Physical Exam During the physical exam, your doctor will listen to your heart and lungs with a stethoscope. He or she also will check your ankles and legs for swelling and your lips and skin for a bluish color. These are signs of PH. Diagnostic Tests and Procedures Your doctor may recommend tests and procedures to confirm a diagnosis of PH and to look for its underlying cause. Your doctor also will use test results to find out the severity of your PH. Tests and Procedures To Confirm a Diagnosis Echocardiography. Echocardiography (EK-o-kar-de-OG-ra-fee), or echo, uses sound waves to create a moving picture of your heart. This test can estimate the pressure in your pulmonary arteries. Echo also can show the size and thickness of your right ventricle and how well it's working. Chest x ray. A chest x ray takes pictures of the structures in your chest, such as your heart, lungs, and blood vessels. This test can show whether your pulmonary arteries and right ventricle are enlarged. The pulmonary arteries and right ventricle may get larger if the right ventricle has to work hard to pump blood through the pulmonary arteries. A chest x ray also may show signs of an underlying lung disease that's causing or contributing to PH. EKG (electrocardiogram). An EKG is a simple, painless test that records the heart's electrical activity. This test also shows whether your heart's rhythm is steady or irregular. An EKG may show whether your right ventricle is enlarged or strained. Right heart catheterization. This procedure measures the pressure in your pulmonary arteries. It also shows how well your heart is pumping blood to the rest of your body. Right heart catheterization (KATH-e-ter-ih-ZA-shun) can find any leaks between the left and right side of the heart. During this procedure, a thin, flexible tube called a catheter is put into a blood vessel in your groin (upper thigh) or neck. The tube is threaded into the right side of your heart and into the pulmonary arteries. Through the tube, your doctor can do tests and treatments on your heart. Tests To Look for the Underlying Cause of Pulmonary Hypertension PH has many causes, so many tests may need to be done to find its underlying cause. Chest CT scan. A chest computed tomography (to-MOG-ra-fee) scan, or chest CT scan, creates pictures of the structures inside your chest, such as your heart, lungs, and blood vessels. These pictures can show signs of PH or a condition that may be causing PH. Chest MRI. Chest magnetic resonance imaging, or chest MRI, shows how your right ventricle is working. The test also shows blood flow in your lungs. Chest MRI also can help detect signs of PH or an underlying condition causing PH. Lung function tests. Lung function tests measure how much air you can breathe in and out, how fast you can breathe air out, and how well your lungs deliver oxygen to your blood. These tests can help detect a lung disease that may be causing PH. Polysomnogram (PSG). This test records brain activity, eye movements, heart rate, and blood pressure while you sleep. A PSG also measures the level of oxygen in your blood. A low oxygen level during sleep is common in PH, and it can make the condition worse. A PSG usually is done while you stay overnight at a sleep center. For more information about this test, go to the Diseases and Conditions Index Sleep Studies article. Lung ventilation/perfusion (VQ) scan. A lung VQ scan measures air and blood flow in your lungs. This test can help detect blood clots in your lung's blood vessels. Blood tests. Blood tests are used to rule out other diseases, such as HIV, liver disease, and autoimmune diseases (such as rheumatoid arthritis). Finding Out the Severity of Pulmonary Hypertension Exercise testing is used to find out the severity of PH. This testing consists of either a 6-minute walk test or a cardiopulmonary exercise test. A 6-minute walk test measures the distance you can quickly walk in 6 minutes. A cardiopulmonary exercise test measures how well your lungs and heart work while you exercise on a treadmill or bicycle. During exercise testing, your doctor will rate your activity level. Your level is linked to the severity of your PH. The rating system ranges from class 1 to class 4. Class 1 has no limits. You can do regular physical activities, such as walking or climbing stairs. These activities don't cause PH symptoms, such as tiredness, shortness of breath, or chest pain. Class 2 has slight or mild limits. You're comfortable while resting, but regular physical activity causes PH symptoms. Class 3 has marked or noticeable limits. You're comfortable while resting. However, walking even one or two blocks or climbing one flight of stairs can cause PH symptoms. Class 4 has severe limits. You're not able to do any physical activity without discomfort. You also may have PH symptoms while at rest. Over time, you may need more exercise tests to find out how well your treatments are working. Each time testing is done, your doctor will compare your activity level with the previous one. Treatment Pulmonary hypertension (PH) has no cure. However, treatment may help relieve symptoms and slow the progress of the disease. PH is treated with medicines, procedures, and other therapies. Treatment will depend on what type of PH you have and its severity. (For more information, go to "Types of Pulmonary Hypertension.") Group 1 Pulmonary Arterial Hypertension Group 1 pulmonary arterial hypertension (PAH) includes PH that's inherited, that has no known cause, or that's caused by certain drugs or conditions. Treatments for group 1 PAH include medicines and medical procedures. Medicines Your doctor may prescribe medicines to relax the blood vessels in your lungs and reduce excess cell growth in the blood vessels. As the blood vessels relax, more blood can flow through them. Your doctor may prescribe medicines that are taken by mouth, inhaled, or injected. Examples of medicines for group 1 PAH include: Phosphodiesterase-5 inhibitors, such as sildenafil Prostanoids, such as epoprostenol Endothelin receptor antagonists, such as bosentan and ambrisentan Calcium channel blockers, such as diltiazem Your doctor may prescribe one or more of these medicines. To find out which of these medicines works best, you'll likely have an acute vasoreactivity test. This test shows how the pressure in your pulmonary arteries reacts to certain medicines. The test is done during right heart catheterization. Medical and Surgical Procedures If you have group 1 PAH, your doctor may recommend one or more of the following procedures. Atrial septostomy (sep-TOS-toe-me). For this procedure, a thin, flexible tube called a catheter is put into a blood vessel in your leg and threaded to your heart. The tube is then put through the wall that separates your right and left atria (the upper chambers of your heart). This wall is called the septum. A tiny balloon on the tip of the tube is inflated. This creates an opening between the atria. This procedure relieves the pressure in the right atria and increases blood flow. Atrial septostomy is rarely done in the United States. Lung transplant. A lung transplant is surgery to replace a person's diseased lung with a healthy lung from a deceased donor. This procedure may be used for people who have severe lung disease that's causing PAH. Heart–lung transplant. A heart–lung transplant is surgery in which both the heart and lung are replaced with healthy organs from a deceased donor. Group 2 Pulmonary Hypertension Conditions that affect the left side of the heart, such as mitral valve disease, can cause group 2 PH. Treating the underlying condition will help treat PH. Treatments may include lifestyle changes, medicines, and surgery. Group 3 Pulmonary Hypertension Lung diseases, such as COPD (chronic obstructive pulmonary disease) and interstitial lung disease, can cause group 3 PH. Certain sleep disorders, such as sleep apnea, also can cause group 3 PH. If you have this type of PH, you may need oxygen therapy. This treatment raises the level of oxygen in your blood. You'll likely get the oxygen through soft, plastic prongs that fit into your nose. Oxygen therapy can be done at home or in a hospital. Your doctor also may recommend other treatments if you have an underlying lung disease. Group 4 Pulmonary Hypertension Blood clots in the lungs or blood clotting disorders can cause group 4 PH. If you have this type of PH, your doctor will likely prescribe blood-thinning medicines. These medicines prevent clots from forming or getting larger. Sometimes doctors use surgery to remove scarring in the pulmonary arteries due to old blood clots. Group 5 Pulmonary Hypertension Various diseases and conditions, such as thyroid disease and sarcoidosis, can cause group 5 PH. An object, such as a tumor, pressing on the pulmonary arteries also can cause group 5 PH. Group 5 PH is treated by treating its cause. All Types of Pulmonary Hypertension Several treatments may be used for all types of PH. These treatments include: Diuretics, also called water pills. These medicines help reduce fluid buildup in your body, including swelling in your ankles and feet. Blood-thinning medicines. These medicines help prevent blood clots from forming or getting larger. Digoxin. This medicine helps the heart beat stronger and pump more blood. Digoxin sometimes is used to control the heart rate if abnormal heart rhythms, such as atrial fibrillation or atrial flutter, occur. Oxygen therapy. This treatment raises the level of oxygen in your blood. Physical activity. Regular activity may help improve your ability to be active. Talk with your doctor about a physical activity plan that's safe for you. Research is ongoing for better PH treatments. These treatments offer hope for the future. Living With Pulmonary hypertension (PH) has no cure. However, you can work with your doctor to manage your symptoms and slow the progress of the disease. Ongoing Care Follow your treatment plan as your doctor advises. Call your doctor if your PH symptoms worsen or change. The earlier symptoms are addressed, the easier it is to treat them. Some symptoms, such as chest pain, may require emergency treatment. Ask your doctor when you should call him or her or seek emergency care. Also, talk with your doctor before taking any over-the-counter medicines. Some medicines can make your PH worse or interfere with the medicines you're taking for PH. Ask your doctor whether you should get a pneumonia vaccine and a yearly flu shot. You may have a complex schedule for taking medicines. Call your doctor or nurse if you're having problems with this schedule. Knowing the names of your medicines and how they work is helpful. Keep a list of your medicines with you. Don't stop or change medicines unless you talk with your doctor first. Pay careful attention to your weight. You may want to keep a daily record of your weight. You should weigh yourself at the same time each day. If you notice a rapid weight gain (2 or more pounds in 1 day or 5 or more pounds in 1 week), call your doctor. This may be a sign that your PH is worsening. Pregnancy is risky for women who have PH. Consider using birth control if there is a chance you may become pregnant. Ask your doctor which birth control methods are safe for you. Lifestyle Changes Making lifestyle changes can help you manage your symptoms. These changes will depend on the type of PH you have. Talk with your doctor about which lifestyle changes can help you. Quit Smoking If you smoke, quit. Smoking makes PH symptoms worse. Ask your doctor about programs and products that can help you quit. Also, avoid exposure to secondhand smoke. For more information about how to quit smoking, go to the Diseases and Conditions Index Smoking and Your Heart article and the National Heart, Lung, and Blood Institute's (NHLBI's) "Your Guide to a Healthy Heart." Although these resources focus on heart health, they both include general information about how to quit smoking. Follow a Healthy Diet Following a healthy diet and maintaining a healthy weight are part of a healthy lifestyle. A healthy diet includes a variety of fruits, vegetables, and whole grains. It also includes lean meats, poultry, fish, and fat-free or low-fat milk or milk products. A healthy diet also is low in saturated fat, trans fat, cholesterol, sodium (salt), and added sugar. Talk with your doctor about whether you need to limit the amount of salt and fluids in your diet. Ask him or her whether you also need to regulate foods that contain vitamin K. These foods can affect how well blood-thinning medicines work. Vitamin K is found in green leafy vegetables and some oils, such as canola and soybean oil. For more information about following a healthy diet, go to the NHLBI's Aim for a Healthy Weight Web site, "Your Guide to a Healthy Heart," and "Your Guide to Lowering Your Blood Pressure With DASH." All of these resources include general advice about healthy eating. The DASH eating plan focuses on reduced-sodium foods, which may be helpful if your doctor advises you to limit the salt in your diet. Be Physically Active Physical activity is an important part of a healthy lifestyle. Try to do physical activity, such as walking, regularly. This will keep your muscles strong and help you stay active. Ask your doctor how much activity is safe for you. Your doctor may tell you to limit or avoid certain activities, such as: Those that cause straining, such as lifting heavy objects or weights. Sitting in a hot tub or sauna or taking long baths. These activities can lower your blood pressure too much. Flying in an airplane or traveling to high-altitude areas. Your doctor may ask you to use extra oxygen during air travel. Avoid activities that cause breathing problems, dizziness, or chest pain. If you have any of these symptoms, seek care right away. Emotional Issues and Support Living with PH may cause fear, anxiety, depression, and stress. You may worry about your medical condition, treatment, finances, and other issues. Talk about how you feel with your health care team. Talking to a professional counselor also can help. If you're very depressed, your doctor may recommend medicines or other treatments that can improve your quality of life. Joining a patient support group may help you adjust to living with PH. You can see how other people who have the same symptoms have coped with them. Talk with your doctor about local support groups or check with an area medical center. Support from family and friends also can help relieve stress and anxiety. Let your loved ones know how you feel and what they can do to help you. 

Answer: Pulmonary hypertension (PH) begins with inflammation and changes in the cells that line your pulmonary arteries. Other factors can also cause PH. For example, if the walls of the arteries tighten, blood clots may become stiff from an overgrowth of cells.