PAH can be difficult to diagnose in a routine medical exam because the most common symptoms of PAH, such as breathlessness, fatigue and dizziness, are also associated with many other conditions. If your doctor suspects that you have PAH, he or she will want to review your medical and family history, perform a physical exam and perform one or more diagnostic tests.
To determine if you have PAH, and what type, your medical team will schedule specialized tests. If your medical team suspects PAH as a result of one or more of the following tests, they will go on to schedule a right-heart catheterization, which is required to confirm diagnosis.
Blood tests check the oxygen levels in the blood, they observe liver and kidney function, and they identify whether the patient has collagen vascular disease, thyroid problems, signs of infection or HIV antibodies. One test, the brain natriuretic peptide, helps to assess the strain on the heart and may also be used to monitor response to treatment.
Chest X-rays can reveal an enlarged right ventricle or pulmonary arteries. Chest X-rays can also show signs of emphysema or scarring (interstitial fibrosis) of the lungs.
An electrocardiogram checks the electrical impulses of the heart. Electrodes are attached to the patient's skin, and a recording of these impulses is made. However, an ECG alone is not enough to indicate a PAH diagnosis. If your doctor performs an ECG, he or she will also perform one or more additional procedures to identify PAH.
In this procedure, electrodes are placed on the patient's skin, and a sonogram of the heart is taken. This painless procedure is often used to make a preliminary diagnosis by estimating the pressures in the right heart and assessing how well the heart is functioning. Other heart conditions that produce symptoms similar to PAH may be diagnosed with an echocardiogram. In addition, an echocardiogram may be used to monitor a patient's condition.
These tests measure how much air your lungs can hold, how much air moves in and out of them and the lungs' ability to exchange oxygen. These tests may be performed to potentially identify its cause.
- Exercise Tolerance Test (Six-Minute Walk Test)
During this test, a patient will be asked to perform an exercise, most commonly a six-minute walk. The purpose is to identify the patient's exercise tolerance level.
- Nuclear Scan (Ventilation/Perfusion Scan or V/Q Scan)
This diagnostic tool tests for blood clots in the lungs by producing a picture of air and blood flow to the lungs. A small dose of radioactive material is breathed in and another small dose is injected via a blood vessel into the lungs. The doctor will review the images that are produced to evaluate the health of the lungs.
The Gold Standard for PAH Diagnosis
Right-Heart Catheterization
If the results of initial tests point to PAH, your doctor will schedule a right-heart catheterization (commonly referred to as a “right heart cath”). Right-heart catheterization is one of the most accurate and useful tests to get a definitive diagnosis for PAH. This is the only test that directly measures the pressure inside the pulmonary arteries, and it should be done in all patients at least once to confirm a patient's diagnosis of PAH. During the test, doctors insert a catheter (a thin rubber tube) through a large vein in the patient's groin or neck. They then pass the catheter up into the patient's heart to measure the blood pressure in the right side of the heart and lungs.
Vasodilator Study (Acute Vasodilator Challenge)
This test is used for patients who have already been diagnosed with PAH to determine how much their pulmonary blood vessels can relax over a brief period of time. Its main purpose is to screen for patients who might respond favorably to calcium channel blockers, a form of medication. The test can also help determine the patient's prognosis. With a right heart catheter in place, the patient is given drugs that relax the pulmonary arteries. The test drug is given to the patient in higher and higher doses, pausing at each dose to see how the patient reacts. Once a significant response occurs or the side effects become intolerable, the test is considered complete.
