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Pulmonary hypertension (PH) refers to high blood pressure in the blood vessels that travel between the heart and lungs. Pulmonary venous hypertension (PVH) and pulmonary arterial hypertension (PAH) are each a subset of PH and have different causes and treatments.
The World Health Organization (WHO) Classification of Pulmonary Hypertension includes five distinct groups of PH. PAH makes up group 1, and PVH is included in group 2. Although PAH is designated as group 1, it’s a rare disorder, with 500 to 1,000 new cases diagnosed each year. Conversely, WHO group 2 is the most common classification of PH. Across subsets, pulmonary hypertension occurs more often in women than in men.
Both PVH and PAH are characterized by increased blood pressure in the lungs. The differences in these conditions lie in what causes this greater pressure.
PVH is caused by left heart disease — often left ventricular failure, which occurs when the left side of the heart weakens or stiffens. The left side of the heart pumps oxygen-rich blood into the body’s circulatory system. When the left side is weak, the heart’s left ventricle has difficulty pumping, leading to reduced output. Likewise, when the left side of the heart is stiff, it can’t expand to allow enough blood to enter. In either case, blood can back up into the lung’s blood vessels, which increases blood pressure.
Valvular disease is another type of left-sided heart disease. Valves are small pieces of tissue in the heart that ensure that blood flows from right to left. When the valves become narrow or leaky, blood can start flowing in the wrong direction, causing a backup of pressure in the lungs’ blood vessels. For example, mitral valve disease occurs when the valve between the heart’s upper left and lower left chambers (the left atrium and left ventricle, respectively) doesn’t close properly.
On the other hand, PAH is caused by changes in the blood vessels connecting the right side of the heart to the lungs. The heart’s right side takes oxygen-low blood from the body and circulates it toward the lungs to pick up more oxygen. The changes in PAH include blood vessel narrowing — a process called vascular remodeling — which blocks or reduces blood flow. In response, the right side of the heart pumps harder, causing hypertrophy (the muscle thickens and enlarges). Hypertrophy may be helpful at first, but it eventually makes the heart less able to pump properly.
As mentioned above, PVH is a type of pulmonary hypertension that arises from problems with the muscles or valves of the left side of the heart. Regardless of the type of left-sided heart disease causing it, PVH is generally considered a singular condition.
On the other hand, there are several types of PAH. In some cases, no cause can be identified, which is known as idiopathic PAH. Other types of PAH are associated with other illnesses or related to environmental or genetic factors.
Many chronic health conditions are linked with PAH. They include connective tissue diseases, such as scleroderma, and congenital heart diseases. In addition, PAH can develop in people with HIV. Lupus, an inflammatory disorder, is also associated with PAH.
A person may develop PAH as the result of environmental triggers. This includes the use of drugs, particularly certain appetite suppressants or amphetamines. PAH may also occur due to toxin exposure.
According to NORD, about 15 percent to 20 percent of people with PAH have heritable PAH, in which an abnormal form of a gene that causes PAH is passed down between generations. Most commonly, heritable PAH is caused by mutations (changes) in the BMPR2 gene.
Other genes with a link to PAH have also been discovered. However, these are largely associated with spontaneous mutations (not inherited from a relative) or are found in people who don’t have a family history of PAH.
The symptoms of PVH and PAH are similar to those found in other types of pulmonary hypertension but vary in how they show up. Some people may not experience symptoms until their condition is advanced. The way a person with PVH or PAH experiences symptoms depends on co-occurring medical conditions as well as sex, age, and other factors.
Common early symptoms of PAH and PVH may include:
Later symptoms of PVH and PAH may also include:
Because these two subsets of pulmonary hypertension have similar symptoms, PVH can be mistaken for PAH. The diagnosis process involves first determining whether a person has PH, then determining the specific type by identifying the underlying cause. It’s important to be able to differentiate between PAH and PVH because they call for different treatments.
When diagnosing pulmonary hypertension and determining the origin, doctors look for heart and lung abnormalities. They’ll check for changes in blood flow within the lung’s blood vessels. They’ll ask about a family history of PH or other pulmonary blood vessel disease. Many tests can help with this process.
The initial test for PH is often an echocardiogram. This noninvasive diagnostic test uses ultrasound waves to get an image of the heart while it beats that can show physical abnormalities, like thickened ventricles. Advances in echocardiographic technology allow doctors to image the heart two-dimensionally and even three-dimensionally to measure its size and functions in real time.
Other common tests a doctor may perform include:
The only definitive test for PAH is an invasive procedure called right heart catheterization (RHC), sometimes called pulmonary artery catheterization. RHC measures blood pressure in the lungs (called mean pulmonary arterial pressure) and how much blood the heart is pumping. A PH medication called nitric oxide is sometimes given during RHC to help relax the lungs’ blood vessels.
To perform RHC, a cardiologist guides a catheter (a thin tube) through a hole in the skin (usually in the neck, arm, or groin) up to the heart and pulmonary arteries. A person with PAH will have a mean pulmonary arterial pressure of 20 millimeters of mercury (mm Hg) or higher.
Other measurements commonly taken during RHC include:
These measurements shed light on a person’s total cardiovascular health and can help rule out PVH.
A doctor may perform a few different tests to confirm whether a person with pulmonary hypertension has PVH. In addition to right heart catheterization, an ECG can be used to identify an enlarged left ventricle.
Pulmonary capillary wedge pressure (PCWP) is another measurement used to confirm whether a person has PVH or PAH. Taking this measurement involves an invasive procedure, traditionally done by guiding a balloon-tipped catheter through branches of the pulmonary arteries. The balloon is inflated to obstruct blood flow and create pressure, which is then measured. People with PVH typically have a PCWP greater than or equal to 15 mm Hg.
PVH can be diagnosed noninvasively using Doppler echocardiography to measure how much blood is being pumped and observe the way blood flows through the heart. Abnormalities in blood flow on the left side of the heart may indicate left ventricle failure or mitral valve stenosis.
Treatment plans for pulmonary venous hypertension and pulmonary arterial hypertension vary depending on the condition’s underlying cause. Notably, targeted treatments are available for PAH but not PVH. It’s important to have an accurate diagnosis because treatments for one condition can harm someone with the other condition.
Treatments for PAH focus on decreasing blood pressure in the lungs by opening the pulmonary arteries. Medications are the first line of treatment. Common PAH drugs include phosphodiesterase 5 inhibitors (such as sildenafil), which act as vasodilators to open up blood vessels, and endothelin receptor antagonists, which prevent blood vessels from constricting (narrowing). Vasoconstricting medications could have a negative impact on people with PAH.
Some people have a form of PAH called chronic thromboembolic pulmonary hypertension (CTEPH). In CTEPH, small blood clots increase the pressure inside the pulmonary artery. Treatment options for people with CTEPH include surgeries to remove blockages or expand the arteries using balloon catheters.
In severe PAH cases, a lung transplant may be required.
Treatments for PVH are based on the reason for left heart disease. Addressing fluid retention is an important part of the PVH treatment plan, which often includes diuretics.
Other medications that can control blood pressure and prevent the worsening of left-sided heart disease include:
These medications can help lower blood pressure and reduce the work of the heart.
Pulmonary vasodilator medications, which are often prescribed for PAH, are not generally recommended for PVH, and more research regarding these therapies is needed.
People with PVH caused by valve stenosis or narrowing may benefit most from surgery to repair the valve.
On myPHteam, the social network for people with pulmonary hypertension and their loved ones, more than 53,000 members come together to ask questions, give advice, and share their stories with others who understand life with pulmonary hypertension.
Are you living with pulmonary venous hypertension or pulmonary arterial hypertension? Share your experience in the comments below, or start a conversation by posting on your Activities page.
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