Medical Issues

Diagnostic Process

Diagnosis and Assessment of Pulmonary Arterial Hypertension


Pulmonary Hypertension (PH) is rarely picked up in a routine medical examination. Even in its later stages, the signs of the disease can be confused with many other conditions. Thus, much time can pass between the time the symptoms of PH first appear and a definite diagnosis is made.

Pulmonary Hypertension (PH) and Idiopathic Pulmonary Arterial Hypertension (PAH) is a diagnosis of exclusion. Pulmonary Arterial Hypertension is particularly difficult as there is no apparent underlying cause, such as a chronic pulmonary disease, blood clots in the lung, sleep apnea, serious liver disease, some forms of congenital heart disease or any other disorder that can be found to explain the elevated pulmonary artery pressure.  Since both Pulmonary Hypertension and Pulmonary Arterial Hypertension can exist as a secondary condition, treatment of the underlying disorder will become a primary part of the overall treatment plan.

The first tests on the list below help the doctor determine how well the heart and lungs are performing. If the results of these tests do not give the doctor enough information, the doctor should perform a cardiac catheterization. The procedures, discussed below, are some of the most frequently used tools the doctor needs in order to make certain that the patient's problems are due to Pulmonary Hypertension and not to some other condition.

Source: National Heart, Lung, and Blood Institute, Division of Lung Diseases, Primary Pulmonary Hypertension

Tests used to Diagnose Pulmonary Hypertension:

Pulmonary Function Test (Spirometry)
Ventilation/Perfusion (V/Q) Scan
Right-Heart Cardiac Catheterization
Other Tests & Equipment You May Encounter

Categorizing the Severity of PAH:
Functional Classification

The electrocardiogram (ECG or EKG) produces a record of the electrical activity produced by the heart. An abnormal ECG may indicate that the heart is undergoing unusual stress. In addition to the usual ECG performed while the patient is at rest, the doctor may order an exercise ECG. This type of ECG helps the doctor evaluate the performance of the heart during exercise, for example, while walking a treadmill.

In an echocardiogram, the doctor or technician uses sound waves to map the structure of the heart by placing a device that looks similar to a microphone on the patient's chest.  In a few patients, where it is not possible to produce a good view of the heart through the chest wall, a transesophageal echocardiogram can be performed.  In this procedure, the patient is sedated and the probe is placed within the swallowing tube, which brings it into a perfect position directly behind the heart. The instrument sends harmless sound waves through the heart, which are then reflected back to display a real-time image of the beating heart's structure on a screen. A record is made on paper or recorded digitally for display on a computer. The moving images can show how well the heart is functioning. The still pictures permit the doctor to measure the size of the heart and the thickness of the heart muscle.  In the patient with severe Pulmonary Hypertension, the still pictures will show that the right side of the heart is enlarged.  It is also possible to achieve a fairly accurate estimate of the pulmonary artery pressure (PAP) by taking certain measurements and applying mathematical calculations to those. Echocardiograms are helpful in the diagnosis, exclusion of some of the other causes of Pulmonary Hypertension and can be useful in monitoring the response to treatment on a periodic basis.

It’s also possible that your doctor may order a Stress Echocardiogram.  This may be performed if a patient’s resting pulmonary artery pressure appears to be normal and there is still concern that Pulmonary Hypertension is present.  The test involves exercising on a treadmill or stationary cycle.  An echocardiogram is performed prior to and after the exercise.  This can be especially important because some people with Pulmonary Hypertension may have normal resting pressures but very elevated exercise induced pressures.

Pulmonary Function Tests (Spirometry)
A variety of tests called pulmonary function tests (PFT’s) evaluate the way your lungs exchange air. In these procedures, the patient breathes in and out through a mouthpiece while following the instructions from the technician. The patient's breathing patterns are measured and recorded to produce what's known as a spirogram.  This spirogram allows the doctor to measure lung volume (how much air the lungs hold) and the airflow in and out of the various portions of the lungs. Some restriction in air movement is commonly seen in patients with Pulmonary Hypertension. This restriction is thought to be due, in part, to the increased stiffness of the lungs resulting from changes in the lung structure and the high blood pressure within the pulmonary vessels. PFT's can also help to detect other lung disorders that may exist alongside or as underlying problems contributing to Pulmonary Hypertension.

Ventilation/Perfusion (V/Q) Lung Scan
A perfusion lung scan shows the pattern of blood flow in the lungs.  It can also tell the doctor whether a patient has large blood clots in the lungs which can cause a secondary form of Pulmonary Hypertension. In the perfusion scan, the doctor injects a radioactive substance into a vein. Immediately after the injection, the chest is scanned to see the pattern that the injected substance shows. Areas in the lung where blood clots are blocking the flow of blood will show up as blank or clear areas. Two different patterns of pulmonary perfusion can be seen in patients with PH who do not have blood clots in the lungs. One is a normal pattern of blood distribution; the other shows a scattering of patchy abnormalities in blood flow. A major reason for doing a perfusion scan is to distinguish those patients whose Pulmonary Hypertension is due to blood clots in the lungs.

Right-Heart Cardiac Catheterization
In right-heart cardiac catheterization, the doctor places a thin, flexible tube, or catheter, through a patient's arm, leg, or neck vein.  The catheter is then threaded through the vein into the right ventricle and then into the pulmonary artery. Most important in terms of Pulmonary Hypertension is the ability of the doctor to get a precise measure of the blood pressure within the right side of the heart and the pulmonary artery. It must be performed in the hospital by a physician who specializes in the procedure. During catheterization, the doctor can also evaluate the right heart's pumping ability.  This is done by measuring the amount of blood pumped out of the right side of the heart with each heartbeat.  Doctors sometimes take this opportunity to test proven treatments on the patient undergoing catheterization.  If the physician finds very high pressures during the catheterization, he/she may introduce Flolan or another drug directly into the heart in order to measure the response in the pulmonary artery.  This often helps guide the patient’s treatment plan.

Other Tests & Equipment You May Encounter

Six Minute Walk Test
One of the simplest tests doctors often use to assess exercise tolerance, is the six-minute walk. Typically a technician will take your resting blood pressure, measure your blood oxygen saturation by placing a little clip on your finger that is known as a pulse oximeter and then you will be asked to walk as quickly as you can without pausing or stopping, while the technician watches the clock. This test is often conducted in a long inner hallway where the distances have been mapped. At the end of the six minutes, the technician will have you sit, your blood pressure and blood sats will again be taken and you will be asked to describe your shortness-of-breath. This test is often repeated during your regular check-up appointments, as it is a good way to monitor improvements or deterioration of your condition

Pulse Oximetry
With any heart or lung disorder, there is the possibility that an adequate amount of oxygen may not be present in your bloodstream. Pulse oximetry is a simple non-invasive method of monitoring the percentage of hemoglobin (Hgb or Hb) which is saturated with oxygen. The pulse oximeter consists of a probe attached to the patient's finger or ear lobe which is either linked to or part of a computerized unit. The unit displays the percentage of Hgb saturated with oxygen, a calculated heart rate and in some models, a graphical display of the blood flow past the probe.  In patients with Pulmonary Hypertension, the oxygen level in the blood can be reduced and this simple test will detect that.

Sleep Study
Your physician may order an overnight sleep study as sleep disorders can either cause or greatly impact a PH prognosis.  The study itself consists of an overnight stay in a sleep clinic where monitoring takes place by a qualified sleep technician.  During the study they will monitor your sleep quality, record any signs of apnea or breathing difficulties, as well as your REM (dream) time and other indicators of sleep disturbance.  The final report is compiled and deciphered by the physician in charge of the clinic.  A summarized report should be available to you and your doctor for discussion.

After your doctor has evaluated most or all of the above tests, you will be placed in a functional class and assigned a number. This is a way to categorize your level of impairment from Pulmonary Hypertension.  Your classification may change over time and may at times be better and sometimes it may be worse.  One of the goals of treatment is to keep you in as low a classification group as possible.

When you hear your doctor talk about your pulmonary artery pressure (PAP), keep in mind that it does not tell the whole story. Doctors look at the entire picture and include lung pressure, heart and lung function as well as exercise tolerance in making their assessment. That is why another patient with the same pulmonary artery pressure may fall into a different functional class. There is more to it than just pulmonary artery pressure alone.

We encourage you to be proactive in managing your disease, to go to your office visits with as much information as possible and to take an active role in advocating for yourself. You’ll find some very good advice about getting the most out of your doctor visits in Working With Your Doctors in our Tips & Tricks section.

Functional Classification
Once Pulmonary Hypertension is diagnosed, most doctors will classify the disease according to the WHO Functional Classification for PAH which is a slightly modified version of the functional classification system developed by the New York Heart Association. It is based on patient reports of how much activity they can comfortably undertake.

  • Class 1 – Patients with pulmonary hypertension but without resulting limitation of physical activity. Ordinary physical activity does not cause undue dyspnea or fatigue, chest pain, or near syncope.
  • Class 2 – Patients with pulmonary hypertension resulting in slight limitation of physical activity. They are comfortable at rest. Ordinary physical activity causes undue dyspnea or fatigue, chest pain, or near syncope.
  • Class 3 – Patients with pulmonary hypertension resulting in marked limitation of physical activity. They are comfortable at rest. Less than ordinary activity causes undue dyspnea or fatigue, chest pain, or near syncope.
  • Class 4 – Patients with pulmonary hypertension with inability to carry out any physical activity without symptoms. These patients manifest signs of right heart failure. Dyspnea and/or fatigue may be present even at rest. Discomfort is increased by any physical activity.

June 2016 - Page Reviewed and Updated


Other Resources

American Family Physician
Diagnosis and Treatment of Pulmonary Hypertension

Mayo Clinic - Pulmonary Hypertension
Tests and Diagnosis

The Cleveland Clinic
Pulmonary Hypertension: Causes, Symptoms, Diagnosis, Treatment

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