ABOUT PH
Diagnosis
PH can be difficult to diagnose in routine medical exams because the most common symptoms of PH (breathlessness, fatigue, and dizziness) are also associated with many more common conditions.
When doctors suspect someone has PH, they will review the patient’s medical and family history and perform physical exams and diagnostic tests.
PH is often late to be diagnosed. Medical awareness of PH is improving, but it remains much less common than other heart and lung diseases that can cause similar symptoms. The most important step in diagnosing PH is being aware that it is a possibility and undergoing the key screening test for PH: an echocardiogram.
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When doctors suspect someone has PH, they review the patient’s medical and family history and perform physical exams and diagnostic tests. Before conducting diagnostic tests, your doctor will conduct a physical examination. The doctor will look for visible and/or enlarged veins along the sides of the neck, irregular heart sounds, and swelling in your abdomen, legs, or ankles (edema). The doctor then will perform a series of tests to identify your type of PH and what might have caused it; this will guide your treatment plan.
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Diagnostic tests include blood tests, chest x-rays, electrocardiograms (EKG), echocardiograms, pulmonary function tests (PFTs), exercise tolerance tests (six-minute walk or cardiopulmonary exercise), and CT scans. But the only way to definitively diagnose PH is through right heart catheterization.
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.
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An Electrocardiogram (ECG) 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 PH diagnosis. If your doctor performs an ECG, they will also perform additional procedures to identify PH.
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An Echocardiogram (or “echo”) is a procedure where electrodes are placed on the patient’s skin, and an ultrasound 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 PH may be diagnosed with an echocardiogram. Additionally, an echocardiogram may be used to monitor a patient’s condition and response to treatment over time.
PH Detection Tests
Pulmonary Function 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 the cause of PH.
Computerized Tomography (CT) Chest Scan is a non-invasive test that uses small amounts of radiation to create many precise pictures of the structures in the chest, including the heart and lungs. Sometimes, a dye (also known as “contrast”) is injected into the arm to make the images of certain structures clearer. The test allows healthcare providers to see the lungs in far greater detail than with chest X-rays. Doctors can see the size of the lungs, larger blood vessels in the lungs, and lung tissue. The test looks for evidence of chronic lung diseases (Group 3 PH) or blood clots (Group 4 PH).
Nuclear Scan (Ventilation/Perfusion Scan or V/Q Scan) is a diagnostic tool which 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. This test is recommended to rule out CTEPH in all cases of PH. A Six-Minute Walk Test (6MWT) measures how far a patient can walk in six minutes. It also measures perceived exertion, heart rate, and oxygen saturation (how much oxygen is in the blood). Doctors compare test results from each clinic visit as one way to measure whether PH is improving or worsening.
Blood Tests check oxygen levels in the blood (i.e., with an arterial blood gas), observe liver and kidney function, and identify whether the patient has connective tissue disease (such as lupus or scleroderma), thyroid problems, or signs of infection or HIV. To help assess the function of the heart and to monitor response to treatment, a brain natriuretic peptide (BNP) test or an N-Terminalpro brain natriuretic peptide (NT-proBNP) may be conducted. Some centers measure NT-proBNP while others measure BNP, but both measure the same thing – heart function.
Sleep Studies are occasionally requested in patients at risk for obstructive sleep apnea or low oxygen levels overnight. These can be done at home with equipment to check for snoring and oxygen levels, or may require a complete polysomnogram, where a patient sleeps in a monitored sleep lab.
PH Group Identification Tests
A Six-Minute Walk Test (6MWT) measures how far a patient can walk in six minutes. It also measures perceived exertion, heart rate, and oxygen saturation (how much oxygen is in the blood). Doctors compare test results from each clinic visit as one way to measure whether PH is improving or worsening.
A Cardiopulmonary Exercise Test (CPET) is used to measure blood pressure and oxygen consumption when patients exercise (often on a stationary bike). The test identifies how well both heart and lungs respond to exercise.
Exercise Capacity Test
During a Right Heart Catheterization (RHC or “right heart cath”), a doctor inserts a small tube into a vein in the neck, upper arm, or groin and guides it into the right atrium of the heart. The tube is then guided through the right ventricle into the pulmonary artery. The practitioner will then take several pressure readings and sometimes withdraw blood from the catheter tip.
The doctor will calculate how much blood the heart can pump in a minute (cardiac output) and take a reading called a “wedge” pressure. In this test, a balloon is inflated at the end of the catheter and wedged into a smaller section of one of the pulmonary arteries. The reading gives insight into the pressure on the left side of the heart and can indicate left heart disease that contributes to Group 2 PH. Patients with PAH (Group 1 PH) will have normal wedge pressure.
The only way to definitively diagnose PAH is through right heart catheterization.
PH Hemodynamics: Testing The Heart Muscle
Many of the tests used to diagnose PH can also help identify a patient’s “functional class”. Your providers might require a right heart catheterization periodically or a six-minute walk test at every visit. Those repeated tests help them evaluate your health and – with your input – make the best decisions about your treatment and care. Some reasons doctors order these tests include changes to your health status, events like hospitalizations, or medication changes. If you ever wonder why a test is being run or what the results mean, ask your PH specialist.
After doctors confirm a PH diagnosis and identify the type, they will use other tests to determine how best to treat a patient’s PH, monitor how they respond to treatments, and obtain other information to forecast disease progression.