PH can be difficult to diagnose in a routine medical exam because the most common symptoms of PH — breathlessness, fatigue and dizziness — are also associated with many other more common conditions.
If a doctor suspects that someone has PH, they will review the patient’s medical and family history, perform a physical exam and a series of diagnostic tests. These diagnostic tests give doctors clues as to whether a patient has PH and what type of PH they may have. The types and order of diagnostic tests vary from clinic to clinic. The PH Diagnosis Journey included in this section shows common PH diagnostic tests and the information and conclusions a doctor may get from each.
Some tests used by health care providers who suspect PH include pulmonary function tests, exercise tolerance tests (e.g. a six-minute walk test or cardiopulmonary exercise test) and an echocardiogram. The only definitive way to diagnose PH is by using a right heart catheterization.
Right heart catheterization (RHC or right heart cath) is considered the gold standard test for a definitive diagnosis of PH.
This is the only test that directly measures the pressure and flow inside the heart and blood vessels of the lungs. It should be done in all patients at least once before starting any PH-targeted treatments. All other tests that provide a pressure only offer an estimate of this pressure and need to be confirmed with a right heart cath.
A chest X-ray is a non-invasive test that uses radiation to take a picture of the structures inside the chest. Doctors can look at the heart, lungs, blood vessels and bones. When examining a patient for PH, doctors will look at the general shape of the heart to see if the chambers of the heart are larger than expected; see if the pulmonary arteries are more visible than normal; and look for signs of lung disease, infections or fluid in the lungs (e.g. pleural effusion). With a chest X-ray, doctors may see evidence of heart disease (WHO Group 2 PH) or lung disease (WHO Group 3 PH).
Electrocardiogram (EKG or ECG)
An electrocardiogram is a simple, painless test that shows the electrical activity of the heart. Usually 12 sticky pads are placed on the chest, arms and legs and connected to a machine that prints the electrical activity of the heart. Doctors use this to check how fast the heart is beating, whether the beats are regular, the strength of the electrical pulse in the heart that causes the “beat” and to look for any prior heart damage.
An echocardiogram is an ultrasound of the heart. During an echo, a sticky gel is placed on the chest, near the heart, and a technician or doctor will glide a wand that’s connected to a computer over the gel. The wand will transmit sound waves — which you cannot hear — and a computer will interpret these sound waves as images showing both still pictures and videos of the heart. Doctors will look at how large the heart is and how well it is squeezing, how the right side of the heart looks (remember, this is the side of the heart that pumps blood into the lungs) and how fast the blood is moving. Sometimes doctors use saline or a dye injected into a vein during an echo to help them better see the heart and detect abnormal blood flow. Doctors also use an echo to look for any evidence of left heart disease (WHO Group 2 PH).
Cardiac Magnetic Resonance Imaging (MRI)
If images from an echocardiogram are unclear, doctors may use a cardiac MRI to look at heart function. This is an image of the heart made by powerful magnetic field and radio waves.
Pulmonary Function Tests
Pulmonary function tests (PFTs) are non invasive tests that measure how well the lungs are working. PFTs measure how much air the lungs can hold; how much and how quickly someone can blow air; and information about how oxygen and carbon dioxide are exchanged between the air you breathe in and the blood circulating through the lungs. PFTs help health care providers check to see if there are chronic lung diseases that might be the cause of yoru PH (WHO Group 3 PH). These can include diseases that make it harder for air to flow out of the lungs and diseases where the lungs can’t expand and take in air easily.
Computerized Tomography (CT) Scan
A chest CT scan is a non-invasive test that uses radiation to create many precise pictures of the structures in the chest, including the heart and lungs. Sometimes a dye is injected into the arm (i.e. a contrast) to make the images clearer. This allows health care providers to see the lungs in far greater detail than in a chest x-ray. Doctors can see the size of the lungs, larger blood vessels in the lungs and the lung tissue. This test is used to look for evidence of chronic lung diseases (WHO Group 3).
A pulmonary angiogram is an image of the blood vessels in the lungs after a dye is injected to make them appear more clearly. Health care providers use this test to look at the structure and branching of the blood vessels of the lungs to find evidence of lung disease (WHO Group 3) or chronic blood clots (WHO Group 4).
Ventilation/Perfusion Scan (V/Q scan)
A V/Q scan is a test that helps doctors to rule out whether you have clots in the blood vessels of your lungs. This is the gold standard screening test for WHO Group 4 (CTEPH). In this test, patients get two different scans. During the ventilation scan, patients breathe in a medication mixed with oxygen through a mask. The scanner will take pictures as the patient breathes and the health care provider will be able to see the sections of the lungs that are able to receive air. During the perfusion scan, another medication is injected into a vein in the arm. The scanner then looks at which sections of the lungs are receiving blood flow. If there is a blockage in one of the pulmonary arteries because of a blood clot, that section will not appear as dark on the image, but the ventilation scan could look normal. Doctors will then know to perform more tests to confirm if this section of the lungs has a chronic blood clot and whether this could be removed with a PTE surgery.
Doctors may also take an ultrasound of the legs to check for blood clots that may be contributing to WHO Group 4 PH (CTEPH).
Overnight oximetry is a test that measures oxygen levels in the blood. A plastic clip is worn over the end of a finger and, throughout the night, measures how much oxygen is in the blood. This is a non-invasive test that can be done at home. If oxygen levels drop below a certain point (generally 90 percent, but this varies by clinic), oxygen therapy is recommended.
Polysomnography is a recording of brain waves during sleep. Doctors use this to determine what is causing low oxygen levels, if there are periods where breathing stops and if there is any physical movement (such as restless legs) during these periods. This is generally done overnight at a sleep center.
Blood Tests and Immunology
A small amount of blood is drawn and examined. These tests are used as a general health assessment and to look for markers of specific diseases associated with PAH (WHO Group 1 PH) such as kidney, liver and thyroid function; HIV; connective tissue diseases; etc. Doctors will sometimes look at arterial blood gas (ABG) which measures arterial oxygen and carbon dioxide levels.
Abdominal Ultrasound Scan
If liver disease is suspected, health care providers will perform an ultrasound of organs in the abdomen including the liver, kidneys, gallbladder, spleen and pancreas. Health care providers will likely focus on the liver to check for any evidence of liver disease.