Under Pressure: Understanding Pulmonary Hypertension
Just like those throughout the rest of your body, the blood vessels in the lungs are susceptible to hypertension. Blood pressure in the lungs is a different measurement than blood pressure throughout the rest of the body because our bodies have two circulatory systems:
- Systemic — the one in charge of delivering oxygen throughout the body
- Pulmonary — the one receiving oxygen from the lungs so that the systemic circulation can do its job.
When the blood pressure in the lungs becomes too high, it’s known as pulmonary hypertension (PH).
Types of PH
Pulmonary Arterial Hypertension (PAH)
“PAH is what happens when the blood vessels in the lungs thicken and constrict and the pressure goes up,” said Vallerie McLaughlin, professor of medicine and the director of the Pulmonary Hypertension Program in the Division of Cardiovascular Medicine at the University of Michigan in Ann Arbor. This makes it harder to get blood without oxygen from the right side of the heart to flow through the lungs, become oxygenated and then flow to the left side of the heart, where oxygenated blood is then pumped to the rest of the body. PAH is sometimes referred to as “primary PH.”
PAH is rare, with data suggesting that up to 15 people per million have it. There are various forms of PAH including idiopathic pulmonary arterial hypertension (IPAH) which occurs spontaneously, has no identifiable cause and makes up a little over a third of the overall prevalence of PAH. There also seems to be a genetic component that increases the risk for people with certain gene mutations.
PAH can also be a complication of congenital heart disease or HIV infection. There has also been an association between PAH and certain types of appetite suppressants, as well as illicit drugs like methamphetamine and cocaine.
PH caused by other diseases
Other causes include obstructive and restrictive lung diseases like chronic obstructive pulmonary disease (COPD), and other disorders that cause inflammation or scarring in the lungs. PH may also occur due to sleep disordered breathing, such as sleep apnea or by blood clots in the pulmonary arteries. Certain blood disorders, systemic disorders, metabolic disorders and other various conditions can lead to PH.
“There are a lot of other diseases that can also cause PH like left heart failure or COPD that can be associated with a mild pulmonary hypertension. But those are much different than IPAH,” said McLaughlin. Forms of PH caused by other diseases may sometimes be referred to as “secondary PH.”
Sometimes PH is caused by diseases affecting the left side of the heart. In these cases, PH is a result of higher pressures in the left heart chambers that get transmitted backward to the right chambers and from there into the lungs. “Left heart disease could be systolic dysfunction, diastolic dysfunction, valvular heart disease; anything that elevates the pressure in the left side of the heart,” McLaughlin said.
Systemic high blood pressure is common enough in the population that some people with PH also have high blood pressure; but systemic hypertension itself is not considered a cause of PH.
The symptoms for primary and secondary PH may be similar, and symptoms are usually more severe as the disease progresses. Symptoms may include:
- Shortness of breath
- Chest pain (Angina pectoris)
- Exercise intolerance. Loss of energy.
- Swelling of the arms, legs, ankles or abdomen
- Dry cough
- Raynaud’s phenomenon (chalky white or dusky blue fingers that may be painful and can sometimes be provoked by the cold)
Even minimal activity may provoke symptoms in advanced stages. Patients in advanced stages may experience irregular heartbeat, a racing pulse, syncope and difficulty breathing even at rest.
Diagnosis of pulmonary hypertension is sometimes delayed because its main symptom — shortness of breath — is also a symptom of other, more common and less threatening conditions like asthma. Doctors may look for those more common conditions first. In fact, because PH is often initially misdiagnosed, patients may go months or even years believing they have something other than PH.
“The most common test that makes us start suspecting PH is the echocardiogram where you might see an enlargement of the right heart chambers and the Doppler estimates of the pulmonary pressure,” McLaughlin said.
There are a number of preliminary tests for PH, including blood tests to check the oxygen level, chest X-rays to check for an enlarged heart and lung abnormalities, electrocardiograms and echocardiograms to check the functioning of the heart, lung function tests and exercise tolerance tests.
All of these tests may point to a PH diagnosis, but in order to diagnose it definitively, a right-heart catheterization must be performed. This is the only test that directly measures the pressure inside the pulmonary arteries and heart chambers, and, according to guidelines, it should be done in all patients at least once to confirm a diagnosis of PH.
Secondary PH is generally treated by treating the underlying disease.
PAH is not curable, but it is treatable. “There are about 14 FDA-approved drugs that work in three different categories,” McLaughlin said. One category works to get blood vessels to relax and not overgrow; the second helps to keep vessels from constricting and growing too much; and the third helps to widen or dilate the vessels. All of these ultimately result in easier blood flow. “Often we use more than one drug to try to attack the disease from different angles, because it is a disease with a poor prognosis.” About 15 percent of people with PAH die within one year of their diagnosis.
The most severe cases receive intravenous infusions of medications that require a pump that has to be worn constantly and insertion of a central line, which is a hospital procedure. Patients must maintain this line themselves at home. “That obviously is quite complicated for the patient,” McLaughlin said. “But the quality of life is improved because their breathing is better so they’re more functional. True, they do have to deal with the pump and the side effects of the medication; but we try to balance the improvement in the symptoms versus the side effects.”
Emotional toll on patients and caregivers
McLaughlin said there is a significant emotional toll, especially when patients have looked on the internet and seen information from older studies mentioning a 2.8 year after-diagnosis survival rate. “You can imagine a 50-year-old woman walking in the office thinking she’s got two years to live — it’s devastating,” McLaughlin said. “But those studies were done before we had any of these therapies.”
According to the REVEAL (Registry to Evaluate Early and Long-term Pulmonary Arterial Hypertension Disease Management) Registry from 2012, survival rates have improved considerably: One-, three-, five, and seven year survival rates from diagnosis were 85 percent, 68 percent, 57 percent and 49 percent respectively.)
For some patients, it’s all they can do to get up, take a shower and get dressed, so household duties must be handled by someone else. Of course, anxiety and depression often occur with chronic disease, affecting the patients and family who are caring for them. “I think another issue that really affects PH families these days is that these medications are expensive,” McLaughlin said. “That increases financial stress and uncertainty as well.
“Another aspect I would highlight is that this is a complex disease with multiple complicated medications with numerous side effects. It really takes a multidisciplinary group to care for patients. Centers that specialize in PH are probably in the best interest of the patient.”
There’s good news … and good news
The good news is that PH is relatively rare, and further good news is that there are effective treatments that enable patients to lead more normal lives. But the earlier the diagnosis, the better, so for anyone with shortness of breath, fatigue and chest pain, get checked out.
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