Advanced cardiopulmonary testing can often help diagnose less common causes of breathlessness.
Hidden causes of shortness of breath can make the problem tricky to treat.
Some people say they feel “winded,” while others describe it as fatigue. Either way, shortness of breath puts both easy and more strenuous activities out of reach for many people. Also known as dyspnea, shortness of breath is one of the most common problems people bring to their doctors. The most obvious causes, such as asthma, chronic obstructive pulmonary disease, and coronary artery disease, are relatively easy to uncover with a battery of standard tests.
For some people, however, the source of the problem remains frustratingly elusive. In cases when the cardiologist rules out a heart condition and the pulmonologist says lung disease is not responsible, a primary care physician may not know where to turn for help. “People may go for two years or more and accumulate hundreds of thousands of dollars in medical bills for testing and failed treatments before they get an accurate diagnosis,” says Dr. Aaron Waxman, director of the Dyspnea and Exercise Intolerance Clinic at Harvard-affiliated Brigham and Women’s Hospital.
The paradox of resting tests
In many cases, the barrier to a diagnosis lies in the fact that the routine, noninvasive assessments such as a chest x-ray and lung function tests (see box) are all done at rest. However, in most cases of unexplained shortness of breath, symptoms occur only when the person is active.
For this reason, the dyspnea center team takes a sophisticated approach, which involves monitoring heart and lung function while the person exercises on a stationary bicycle. Doctors use thin, flexible tubes (catheters) to insert pressure-monitoring devices in the pulmonary artery and the radial artery in the arm. Together, these devices show how well oxygen is delivered to and used by the exercising muscles. A mouthpiece sensor (held in the mouth like a small snorkel) measures how efficiently the person takes in oxygen and exhales carbon dioxide. The entire testing process requires a couple of hours at the clinic, although the exercise portion lasts just six to 10 minutes, depending on how rapidly symptoms of breathlessness develop.
Cardiac causes revealed
When it comes to cardiac disease, most common conditions are reliably detected with noninvasive testing or cardiac catheterization. However, in some people, advanced testing is necessary to accurately diagnose heart disorders. “We often see a form of heart failure in which the heart muscle continues to pump relatively normally despite an inability to fill efficiently. Some of these people have not shown the classic signs of heart failure, such as excess fluid buildup, so shortness of breath with exertion may be the only indicator of the disease,” says Dr. Amil Shah, a cardiologist who works with the team at the dyspnea clinic.
Advanced cardiopulmonary testing can also provide insights for diagnosing and treating people who have both a faulty heart valve and pulmonary disease. With exercise, doctors can determine if shortness of breath originates with the heart or the lungs, and if a heart valve replacement procedure would remedy the situation.
What is lung function testing?
Moving on to treatment
The primary goal of the dyspnea clinic is to enable patients to return to their referring doctor with an accurate diagnosis and recommendations for appropriate treatment. Even if there is no medical or surgical solution, approaches such as physical therapy or pulmonary or cardiac rehabilitation may be useful.
Dr. Waxman strongly encourages people who have ongoing problems with breathlessness and haven’t been able to get relief with the treatments they’ve tried to move on to advanced cardiopulmonary testing sooner rather than later. In most cases, the diseases that are uncovered are found in an early stage, so there is a good chance that shortness of breath can be eliminated or at least reduced. For conditions that tend to get worse over time, such as pulmonary hypertension, early detection often enables doctors to slow the progression of the disease.