Pulmonary hypertension (PH) is high blood pressure in the arteries that carry blood from the right side of the heart to the lungs. PH should not be confused with systemic hypertension – high blood pressure in blood vessels throughout the body. Systemic hypertension can damage organs and blood vessels over time, and PH specifically refers to high blood pressure between the heart and lungs. PH is considered a lung disease, and hypertension is considered a cardiovascular (heart and blood vessel) disease. However, PH can cause heart disease, and some types of heart disease can cause PH. PH is a serious and progressive condition that can cause debilitating symptoms and lead to heart failure, dangerous blood clots, and shortened life expectancy.
What Is Pulmonary Hypertension?
The right ventricle of the heart pumps oxygen-depleted blood through the pulmonary arteries into the lungs to receive a fresh supply of oxygen. Changes in the pulmonary arteries, the lungs, or the heart can raise the blood pressure in the pulmonary arteries, making it harder for the right ventricle to pump blood into the lungs. As a result of PH, deoxygenated blood begins to back up in the heart and body, and the supply of oxygenated blood to the tissues of the body becomes insufficient.
PH refers to high blood pressure in the lungs due to any cause. Pulmonary arterial hypertension (PAH) is high blood pressure in the lungs specifically caused by narrowed arteries. There are five main types of PH that are defined by their causes.
Each person with PH is also evaluated for the severity of their symptoms and the limits imposed on their activities. The severity of PH is expressed as one of four functional classes, with people in class I experiencing no symptoms and those in class IV experiencing severe, bilitating symptoms even at rest.
PH is usually diagnosed and treated by a PH specialist. Many types of doctors, including pulmonologists, cardiologists, and rheumatologists, have special training and experience that enables them to specialize in managing PH.
PH can be inherited, a side effect of some drugs or toxins, caused by left-sided heart disease or lung disease or associated with other conditions such as scleroderma or blood clots. Some cases of PH are idiopathic, which means that the cause is unknown.
PH was first described in 1891 by Ernst von Romberg, a German physician. During autopsies, Von Romberg diagnosed what he called “pulmonary vascular sclerosis,” although the cause of the disease was a mystery. Life expectancy for someone diagnosed with PH was only three years, and it took several years to get an accurate diagnosis.
The pulmonary arteries could not be examined in a living person until the procedure for cardiac catheterization was developed. In 1929, German physician Werner Theodor Otto Forssmann developed the catheterization process and tested it on himself. Forssmann inserted the first catheter into his own arm and guided it into his heart. Forssmann’s discovery was largely ignored by the scientific community at the time, but in 1956, he received the Nobel Prize for his work on cardiac catheterization. Today, cardiac catheterization is considered the gold standard for diagnosing PH.
Before the 1950s, mitral stenosis associated with rheumatic fever was a common cause of pulmonary hypertension. Additional causes of PH were discovered in the 1950s. In 1953, researchers found that PH could be caused by pulmonary embolisms. In 1956, American veterinarians R. E. Pierson and Randy Jensen studied the effects of hypoxia at high altitudes as a cause of death in cattle. Pierson and Jensen discovered that living at a high altitude can cause PH.
Cases of PH spiked in the 1960s and ‘70s. Otherwise healthy women in America and Europe were suddenly developing PH because they used appetite suppressants such as aminorex fumarate (Menocil). It is estimated that the use of appetite suppressants increased the risk of developing PH by at least tenfold. The National Institutes of Health (NIH) responded by creating a registry of PH patients in the U.S., which led to more academic and medical research into the condition.
In 1963, American doctor Bruno Balke developed the six-minute walk test to classify the severity of symptoms in individuals with cardiovascular or pulmonary conditions. The longer the distance an individual is able to walk in six minutes without symptoms, the milder the disease severity will be. This test is still used today to determine the functional class of PH cases and track treatment efficacy and disease progression.
Epoprostenol (Flolan), approved for the treatment of pulmonary arterial hypertension in 1995, was the first prostaglandin medication. Prostaglandins dilate the blood vessels of the lungs, increasing the blood flow and the amount of oxygen the cells receive. Prostaglandins can also help slow scarring in the blood vessels of the lungs, slowing the progress of the disease. In the past 20 years, 10 new medications have been approved by the FDA to treat PH. Many new drugs are currently in development.
PH is believed to affect about 25 million people around the world. PH is often undiagnosed or misdiagnosed, so it is difficult to know how many people have PH but do not know it. In the U.S., there are about 200,000 hospitalizations and 15,000 deaths related to PH each year.
PH most commonly develops between the ages of 20 and 60. However, it can affect people of any age, including children. The risk for PH increases with age. Women and people of African descent are more likely to develop PH.
Life expectancy for people with PH depends on many factors, including which type and functional class of PH they have and whether or not they have kidney problems. In general, people who have PH with low-risk features (no kidney disease, higher capacity for exercise, etc.) can expect to live more than 10 years. Newer treatments continue to increase life expectancy for people with PH.
How Is Pulmonary Hypertension Diagnosed?
PH can be difficult to diagnose. Early symptoms of PH are often missed or misinterpreted as heart disease or another pulmonary condition. Once PH is suspected, the first step in diagnosis is a thorough medical and family history. Doctors may use other tests to check how the heart and lungs look and function when PH is suspected. Noninvasive procedures may include blood tests, genetic tests, a pulmonary function test, an electrocardiogram (EKG or ECG), chest X-rays, CT, MRI, and echocardiogram (or echo), which uses ultrasound.
Cardiac catheterization is one of the most conclusive techniques used to diagnose PH. In cardiac catheterization, a thin tube is introduced into an artery and guided into the heart to inject dye that can be seen on X-rays. A ventilation/perfusion (also called V/Q or nuclear) scan involves an injection of radioisotope followed by chest X-rays. The doctor may ask you to undergo polysomnography – a sleep study – if obstructive sleep apnea is suspected.
What Are the Symptoms of Pulmonary Hypertension?
Common symptoms of PH include shortness of breath, fatigue, pressure or pain in the chest, dizziness, fainting, fast or irregular heartbeat, heart palpitations, a grey or blue tinge to the skin, and swelling in the legs, abdomen, or extremities.
How Is Pulmonary Hypertension Treated?
If your PH is caused by another condition, treatment may focus on resolving the underlying condition. Drugs specifically designed to treat PH include vasodilators, endothelin receptor antagonists, and soluble guanylate cyclase (SGC) stimulators. Some medications used to treat PH are also used to treat systemic hypertension and heart disease: Calcium channel blockers, blood thinners, and diuretics (water pills). Some people with PH require oxygen therapy. Pulmonary rehabilitation and lifestyle changes such as improved diet and increased exercise can help people with pulmonary hypertension feel better and live longer.
In certain circumstances, surgeries such as mitral valve repair or replacement, atrial septostomy, or pulmonary thromboendarterectomy (PTE) may be used to treat PH. In severe cases of PH, especially in younger people, the doctor may recommend a lung transplant or a heart-lung transplant.
Is Pulmonary Hypertension Contagious?
No. PH is not contagious.
Is There a Cure for PH?
In the majority of cases, there is no cure for PH. Some people with chronic thromboembolic pulmonary hypertension (CTEPH), a rare type of PH, are cured after undergoing a surgery called pulmonary thromboendarterectomy (PTE).