Pulmonary hypertension is a common complication of chronic diseases that occurs when there is increased blood pressure in the arteries carrying blood from the right side of the heart to the lungs.
Just as you can have hypertension in your arms, you can get high blood pressure in the lungs. Heart failure and chronic obstructive pulmonary disease are the most common causes. More rarely, pulmonary hypertension is caused by genetic mutations, blood clots or unknown reasons.
Since 1973 pulmonary hypertension has been defined as a pulmonary pressure of 25 millimeter of mercury (mmHg) or higher. However, several recent studies, including one from Vanderbilt University Medical Center last year, have demonstrated increased mortality in patients with pressures lower than this threshold. This is known as borderline pulmonary hypertension.
The risk of death is increased even after adjusting for the presence of comorbidities such as cardiovascular, lung, kidney and metabolic disease. Indeed, patients with borderline pulmonary hypertension should be considered an at-risk population, said Evan Brittain, MD, MSCI, corresponding author of the Vanderbilt study.
This raises the question: would early intervention or closer monitoring practices improve clinical outcomes?
Based on these recent studies, including the Vanderbilt findings, the World Symposium on Pulmonary Hypertension is expected to publish an updated definition of pulmonary hypertension later this year, said Brittain, an assistant professor of Medicine in the Vanderbilt University School of Medicine.
“Our primary message is that clinicians should not ignore mildly elevated values,” he said. “Further studies are needed to fully understand how to manage mildly elevated pulmonary pressure values, but when the underlying cause is clear, it should probably prompt more aggressive management of comorbidities and closer surveillance for progression.”
For many years, experts have debated what normal pressure is in the lungs. While it is easy to measure blood pressure in your arms, measuring pulmonary pressure requires an invasive procedure.
Last year Brittain, clinical fellow Tufik Assad, MD, and colleagues conducted a retrospective study of more than 4,300 patients who had undergone right heart catheterization between 1998 and 2014 using Vanderbilt’s de-identified electronic health records.
They discovered that pulmonary pressures that have historically been considered normal or borderline elevated, between 19 and 24 mmHg, were associated with increased mortality compared with lower pulmonary pressures.
In fact, the investigators showed that more than half of the people initially diagnosed with borderline pulmonary hypertension eventually developed overt pulmonary hypertension.
Assad was first author of the paper, published in the journal JAMA Cardiology.
This research was supported by National Institutes of Health grants HL125212 and HL111207, the American Heart Association, the Gilead Scholars Program in Pulmonary Arterial Hypertension, the Cardiovascular Medical Research and Education Foundation and the Klarman Foundation at Brigham and Women’s Hospital.
