The symptoms of pulmonary hypertension can be confused with symptoms of other diseases. In order to make a correct diagnosis, doctors must first exclude other diseases, a process called differential diagnosis. While a differential diagnosis can help point doctors in the right direction for treatment, it can take time. In some cases, diagnosing pulmonary hypertension definitively can take as long as two years.

The first step in the differential diagnosis is a detailed history and physical. Other tests will be necessary to determine if the heart and lungs are working properly. Blood tests, electrocardiograms, echocardiogram, and other non-invasive medical imaging tests are used in diagnosing pulmonary hypertension.

Electrocardiogram

The electrocardiogram, or EKG, is a non-invasive test that graphs the electrical impulses of the heart. The doctor evaluates the EKG for waveforms that suggest damage to the heart as might occur from a previous heart attack or other stress or injury to the heart.

Medical Imaging: Chest X-Ray & Scans

Medical imaging tests are non-invasive tests that take pictures of the inside of the body. Medical imaging tools used in the pulmonary hypertension diagnosis include chest x-ray, echocardiogram and nuclear perfusion scan. A CAT scan or angiography may also be ordered to help with the differential diagnosis.

Chest x-rays outline the size and shape of the heart and the lungs. The doctor can see if the heart is enlarged and if fluid has accumulated in the sac around the lungs, an indication of advanced heart failure.

Another type of medical imaging test is the nuclear lung scan, also known as ventilation perfusion scan or scint. The scint shows how blood flows through the lungs. This test is used to rule out the presence of blood clots in the lungs.

The Echocardiogram

The single most important medical imaging test used in diagnosing pulmonary hypertension is an echocardiogram. The echocardiogram is an ultrasound of the heart. With ultrasound waves a picture of the heart is translated onto a monitor. Using an echocardiogram, the doctor can see the size and shape of the heart as well as how the heart fills with blood and the force of the blood as it is pumped out of the heart.

In pulmonary hypertension, the echocardiogram may show an enlarged, dilated or poorly moving right side of the heart. There may be visible backward flow of the blood through the tricuspid heart valve.

Pulmonary Function Tests

Pulmonary function tests help determine how the lungs are performing. During a pulmonary function test, the nose is pinched closed with a noseclip and the patient is instructed on various breathing exercises. Pulmonary function tests can measure lung volumes, flow rates and the flow of gases into and out of the lungs. The parameters most often studied during a differential diagnosis are lung volume and carbon monoxide diffusion capacity.

Cardiac Catheterization

Cardiac catheterization is the definitive test used in diagnosing pulmonary hypertension. Cardiac catheterization involves the feeding a small catheter into an arm, leg or neck vein, through the right ventricle, and into the pulmonary artery. The catheter directly measures the pulmonary artery pressure as well as the pressure in the right ventricle. Pressures higher than 25 mmHg indicate the presence of pulmonary hypertension. Because cardiac catheterization is an invasive test, other tests are performed first as part of the differential diagnosis.

Pulmonary Hypertension Screening

It is recommended that relatives of patients with primary pulmonary hypertension be screened themselves every three to five years. Patients with sclerosis should be screened annually.

Resources

American Lung Association. (November 2003). Primary pulmonary hypertension (PPH) fact sheet.

Beers, M. H. & Berkow, R. (ed). Primary pulmonary hypertension. The Merck Manual of Diagnosis and Therapy, 17th Edition. Merck Research Laboratories, NJ, 1999.

Fauci, A., Braunwald, E., Isselbacher, K., Wilson, J., Martin, J., Kasper, D., Hauser, S. & Longo, D. (ed). Harrison's Principles of Internal Medicine, 14th Edition. McGraw-Hill, New York, 1998.

Nicod, L. (2003). Pulmonary hypertension. Swiss Medicine Weekly, 133, 103-110.

Pulmonary Hypertension Association. (2002). Pulmonary hypertension: Helpful information for patients and families.