What is the best way to diagnose this?
As described previously, many of the symptoms of PAH are very non-specific. The symptoms may suggest a diagnosis of PAH or point your doctor toward it, but a diagnostic test must be performed to confirm the diagnosis. At this time, there is no specific blood test for pulmonary arterial hypertension, although blood tests may be obtained as described above as part of the standard evaluation for PAH.
The best screening test at this time is a non-invasive test called an echocardiogram ("cardiac ECHO"). This is a type of ultrasound imaging that provides a video picture of the heart while it is beating. From this, your doctors can assess the chambers of the heart for size and function, study the valves between the chambers, and calculate estimated pressures in the pulmonary arteries.
The echocardiogram is not perfect and can either overestimate or underestimate the actual level of the pulmonary pressures, depending on a number of different factors. While it is generally a very good test, correlating well with precise measurements of pulmonary pressures by cardiac catheterization, there are times when there may be discrepancies. Even though an echocardiogram is a very good diagnostic test, anyone who is going to start taking medicines for pulmonary hypertension should have their pulmonary hypertension documented with the most precise tests.
The only definitive test, or so-called "gold standard," is an invasive test called a cardiac or "right heart" catheterization. In this test a direct measurement of the pulmonary pressures is made and a quantitative assessment of the cardiac function can also be obtained.