Post-capillary pulmonary hypertension affects the blood vessels after gas exchange has occurred in the lungs. Treatment typically involves addressing the heart condition that’s playing a part in the high blood pressure.

Pulmonary hypertension (PH) is when blood pressure is high in the blood vessels that transport blood between your lungs and your heart. Over time, it can lead to further health problems, like heart failure and arrhythmia.

Doctors can classify PH as pre-capillary or post-capillary. Below, we delve into more detail about post-capillary PH. We cover what it is, its symptoms, how doctors diagnose and treat it, and more.

Before we discuss post-capillary PH, it’s important to understand how pulmonary circulation works:

  1. Oxygen-depleted blood passes through the right side of the heart and enters the pulmonary arteries, which go to the lungs.
  2. Blood travels through smaller and smaller blood vessels until it reaches the capillaries surrounding the alveoli. The alveoli are tiny air sacs where red blood cells exchange carbon dioxide for fresh oxygen.
  3. Once gas exchange has occurred, freshly oxygenated blood travels through the pulmonary veins and enters the left side of the heart. From here, it’s pumped out of the heart so it can travel to the tissues of your body.

Post-capillary PH affects pulmonary blood vessels after gas exchange has occurred. Left sided heart disease causes it, such as:

Left sided heart disease can cause the left side of the heart to pump blood less effectively. This can cause a backflow of pressure into the blood vessels of the lungs, leading to post-capillary PH.

Post-capillary PH due to left sided heart disease is the most common type of PH. Researchers estimate it affects 23–80% of people with left sided heart disease.

Pre-capillary PH affects the pulmonary blood vessels before gas exchange has occurred. The affected blood vessels have typically narrowed or thickened, which increases blood pressure.

There are several potential causes of pre-capillary PH, including:

It’s also possible for PH to have both a pre- and a post-capillary component. This is called combined pre-capillary and post-capillary PH. Some cases of post-capillary PH can eventually progress to this type of PH.

The World Health Organization (WHO) has defined four functional classes, or stages, of PH. The classes describe the PH’s severity.

The four classes of PH are:

  • Class 1: You can do physical activities without having symptoms.
  • Class 2: Physical activity leads to symptoms. However, you’re still comfortable when you’re at rest.
  • Class 3: You’re limited in the activities you can do. Lighter physical activity causes symptoms. However, you’re still comfortable at rest.
  • Class 4: You cannot do physical activities without having symptoms. You also have symptoms like shortness of breath or fatigue at rest.

The symptoms of post-capillary PH can include:

Conditions other than PH can cause many of the symptoms above. However, if you’re experiencing any concerning symptoms, visit a doctor to find out what’s causing them.

Two tests are mainly used to diagnose PH: echocardiography and right heart catheterization.

An echocardiogram creates an ultrasound image of the heart. It can help predict the presence of PH.

Right heart catheterization can confirm the diagnosis. It involves a healthcare professional inserting a catheter into a large vein in your groin, neck, or arm. This catheter goes up to the right side of your heart and into your pulmonary arteries.

Right heart catheterization can make several measurements that give a doctor an idea of the pressure in blood vessels in your lungs. Three measurements are used to diagnose post-capillary PH:

  • Mean pulmonary arterial pressure (mPAP): MPAP is the average blood pressure in your pulmonary arteries. A healthy mPAP measurement is about 14 millimeters of mercury (mm Hg). People with post-capillary PH have an mPAP of over 20 mmHg.
  • Pulmonary artery wedge pressure (PAWP): PAWP is the pressure measured when a balloon-tipped catheter is wedged in a pulmonary artery. In people with post-capillary PH, PAWP is greater than 15 mmHg.
  • Pulmonary vascular resistance (PVR): PVR measures the resistance against the flow of blood from the pulmonary arteries to the left atrium of the heart. In post-capillary PH, PVR is under three Wood units.

Other tests healthcare professionals may use to diagnose post-capillary PH include:

Treating post-capillary PH often involves addressing the underlying heart issue leading to the increased blood pressure. Medications are one option.

Some of the medications used to address left sided heart disease in post-capillary PH include:

In general, targeted treatments for PAH have not shown the same benefit in people with isolated post-capillary PH. But further studies and the development of novel treatments are ongoing.

Procedures or surgeries may also help some people with post-capillary PH. An example is repairing heart valve disease that’s contributing to PH.

Other potential treatments for post-capillary PH include:

Post-capillary PH affects the blood vessels after gas exchange happens in the lungs. It develops from left sided heart disease, such as left ventricular dysfunction or heart valve disease.

Echocardiography and right heart catheterization can help doctors diagnose post-capillary PH. Treatment mainly involves addressing the heart disease contributing to the high blood pressure.

PH can lead to complications like heart failure and arrhythmia, so it’s important to talk with a doctor if you have symptoms like shortness of breath, fatigue, or persistent cough.

A doctor can work with you to determine what’s causing your symptoms and develop an appropriate treatment plan.