What You Should Know
How do the heart and lungs work?
The heart is a strong muscle in the center of the chest. The major functions of the heart are to pump blood without oxygen to the lung (to pick up oxygen) and to pump blood with oxygen to the rest of the body. The heart is made up of four cavities, also called chambers.
The two upper chambers are called atria and the two lower chambers are called ventricles. The atria receive blood from the body and lungs and the ventricles pump blood to the body and lungs.
The pulmonary artery is one of the many blood vessels involved in this system of blood flow. It is the big blood vessel that transports blood without oxygen from the heart to the lungs. Blood from the right ventricle (the bottom chamber on the right side of the heart) flows into pulmonary artery. In the lungs the pulmonary artery divides many times to create millions of microscopic blood vessels called arterioles. These arterioles branch to every corner of the lung so that the blood can pick up oxygen.
What is pulmonary hypertension?
Pulmonary hypertension means that there is high blood pressure in the blood vessels of the lung (pulmonary means lung). This pulmonary blood pressure is unrelated to the high blood pressure that can be measured by the blood pressure cuff on your arm, which is known as "systemic hypertension". Systemic hypertension is easier to measure and easier to treat than pulmonary hypertension.
What causes pulmonary hypertension?
The high blood pressure in the lungs starts when the blood vessels in the lungs act abnormally. Usually the problem is in the pulmonary arterioles, but sometimes the problem is in the pulmonary veins (the blood vessels that bring blood with oxygen from the lungs to the heart). Three main types of abnormalities of the arterioles include:
- Small muscles in the wall of the arteriole contract and tighten the vessel.
- The inner lining of the arteriole grows too thick and blocks the middle of the blood vessel.
- Blood clots get caught in the blood vessels.
These problems in the blood vessels make it more difficult for the blood to flow through. The blood cannot flow well to the left side of the heart and to the rest of the body, so it gets backed up in the lung. This causes the pressure in the pulmonary artery to increase.
Why do my blood vessels act abnormally?
Some people seem to have genes that make their blood vessels more likely to act abnormal. These patients are said to have "familial" pulmonary hypertension, meaning that it was passed through their family, or "idiopathic" pulmonary hypertension, meaning we do not exactly know what caused the pulmonary hypertension. Certain types of medications, such as diet pills, can cause pulmonary hypertension in some people. Other types of pulmonary hypertension occur when a person has another disease that can affect the blood vessels. These diseases include:
- rheumatologic diseases such as scleroderma and lupus
- liver disease
- thyroid disease
- congenital heart defects (heart problems that you are born with)
- heart disease such as left heart failure or mitral valve disease
- lung diseases such as emphysema, COPD, or sleep apnea
- diseases that cause lots of blood clots
- sickle-cell disease
- diseases that directly affect blood vessels such as sarcoidosis
What are the symptoms of pulmonary hypertension?
The symptoms may be very mild or unnoticeable when the disease first develops. As the disease progresses, symptoms may include:
- Breathlessness, also called shortness of breath. People with pulmonary hypertension first become short of breath when they exercise such as walking up stairs. More severe pulmonary hypertension can cause people to become short of breath when doing light activity or even when resting.
- Fainting, which occurs when the brain does not get enough oxygen due to decreased blood flow.
- Chest pain or tightness.
- Fatigue or extreme tiredness.
- Swelling of the ankles and legs.
What tests will my doctor do to tell if I have pulmonary hypertension?
1) Echocardiogram: the pressure inside the pulmonary artery can be measured by an ultrasound of the heart, also called an echocardiogram. An echocardiogram uses sound waves to provide a picture of the heart. This test is painless, and is often used to make a preliminary diagnosis of pulmonary hypertension.
2) Right heart catheterization: The pressure inside the pulmonary artery can most accurately be measured by a procedure called a right heart catheterization. All patients should have this test done at least once to give a definitive diagnosis of pulmonary hypertension. This procedure involves insertion of a small, thin flexible tube called a catheter into a vein in the groin. From there it is advanced through the heart to the pulmonary artery where it measures the pulmonary artery pressure and the pressure in the right atrium and right ventricle of the heart.
What other tests may be done to help diagnose pulmonary hypertension?
Laboratory blood tests may be done to rule out common causes of pulmonary hypertension, such as:
- Thyroid dysfunction
- Coagulation disorders
- Rheumatologic diseases
- Liver diseases
A chest x-ray may be done and may show that the pulmonary artery is large (red arrow on x-ray to the left). The smaller blood vessels near the outside edges of the lung may not be seen, which is called "pruning" and is another sign of pulmonary hypertension.
An EKG is a painless test that measures the electrical impulses of the heart. It may show thickened muscle of the right side of the heart and irregularities in the electrical conduction of the heart.
Pulmonary Function Tests (PFTs or spirometry) are a series of tests that measure how much air your lungs can hold and how well you blow air out of your lungs. While breathing through a tube you may be asked to take in a deep breath then blow out as quickly as possible. The results are analyzed by a computer to determine whether or not there is a lung problem.
Some tests may be done to check for blood clots in the pulmonary arterioles. These include:V/Q Scan (or ventilation/perfusion scan) which tests air flow (ventilation) and blood flow (perfusion) in the lung. A radioactive dye is injected into a vein and its movement in the pulmonary arteries is tracked by special cameras. Then you will be asked to breathe in a little radioactive gas and the movement of the gas in your lungs will be tracked by cameras. Doctors then compare the blood flow to the airflow within the lungs to detect a blood clot blocking blood flow to part of the lung (red start in the picture above).
- Pulmonary angiography involves insertion of a catheter into a vein in the groin (similar to a cardiac catheterization). A dye will be injected into the pulmonary arteries to detect a clot.
- CT angiogram is a kind of CT scan or "CAT" scan that uses a donut-shaped machine to take 3-D x-rays of the pulmonary artery. In addition to detecting blood clots in the pulmonary artery, these special x-rays can be used to detect some types of lung disease such as emphysema or pulmonary fibrosis.
A sleep study may be done if your doctor suspects that you have sleep apnea. Sleep apnea is when you have periods where you stop breathing during sleep. This study involved an overnight examination in the sleep lab. In the lab, your brain waves and your breathing will be monitored as you sleep.
How is pulmonary hypertension monitored?
After pulmonary hypertension is diagnosed you doctor will want to monitor your pulmonary hypertension to see if it is getting better or worse. Methods for monitoring pulmonary hypertension include:
- Echocardiograms once or twice a year to monitor the blood pressure in their pulmonary artery.
- Some laboratory blood tests may be done to monitor your pulmonary hypertension, such as:
- Brain natriuretic peptide (BNP), which is a marker of strain on the heart caused by the high blood pressure in the right atrium and ventricle
- Uric acid, which is a marker of decreased oxygen delivery to the body due to poor blood flow through the lungs and heart
- You may be asked to do the six minute walk test every time you come to see your doctor. You will be asked to walk down a hallway while your heart rate and the oxygen level in your blood are recorded. The object of the test is to walk as quickly and as far as you can in six minutes. The more you walk the better you are doing! Your blood pressure, heart rate, oxygen level, and feelings of shortness of breath will be measured before and after the test.