The PAH Initiative Learning Library

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Educational videos/presentations

PAH Basics Video

Listen as Dr. Lana Melendres-Groves, a PAH expert, explains the basics of PAH and how the heart, lungs, and blood vessels work together as a cardiovascular team.


Hi, I’m Dr Lana Melendres-Groves, a pulmonary arterial hypertension specialist and director of the pulmonary hypertension program at the University of New Mexico. I have been treating pulmonary diseases for over 12 years with a specialization in PAH for over 9 years. My clinic has treated over 5,000 patients and I currently oversee 250 PAH patients on PAH-specific medicines. In this video, we’ll cover the basics of pulmonary arterial hypertension, also known as PAH. Understanding what PAH is can be confusing because even healthcare providers may tell you different things about it. Some may say your heart doesn’t work as well as it needs to. It’s really about the blood vessels. The real problem is in the lungs or it’s just hypertension. This is why it’s so important to find an experienced PAH specialist to help you. A PAH specialist is a cardiologist or pulmonologist who has had specific training in PAH and understands how challenging this disease really is.

The heart, lungs, and blood vessels all work together as a cardiovascular team and PAH affects each of these vital organs. So let’s start with the heart. You may already know that the heart has 4 chambers. Two chambers are called atria and receive blood from the other parts of the body and the other 2 chambers are called ventricles and pump blood out of the heart. The right atrium receives blue, oxygen-poor blood from the body and the right ventricle pumps that oxygen-poor blood to the lungs where it can pick up oxygen. The left atrium receives red, oxygen-rich blood from the lungs and then the left ventricle pumps the oxygen-rich blood to the rest of the body. Although cardiac diseases, including heart attacks, are more common in the left ventricle, it’s actually the right ventricle that is affected in people who have PAH.

Again, the heart, lungs, and blood vessels all work together. PAH begins when the walls of the blood vessels in the lungs thicken and become more narrow. Because the blood vessels become more narrow, it’s harder for the blood to pass through them. The reduced blood flow that is caused by the narrowed vessels creates increased pressure on the right side of the heart. The right side of the heart tries to compensate by working harder to pump blood through the vessels and into the lungs. Over time, the heart struggles to maintain this level of intensity. It’s like asking your heart to run a marathon every minute of every day and PAH symptoms result. Because sending blood to the lungs is somewhat easier than pumping blood to the entire body, the right ventricle was not designed to work quite as hard as the left, but working so hard to compensate for narrowed blood vessels causes the right side of the heart to enlarge and eventually to weaken so that it wears out and is no longer able to keep up. One analogy that can help with understanding PAH is traffic on a 5-lane highway.

The highway represents the blood vessels and the cars represent the blood cells. Watch what happens to the traffic flow when there is construction. If 2 lanes on the 5-lane highway are closed for construction, it’s harder for the cars to get through. Traffic flow slows down and the cars back up behind the lane closure, causing a traffic jam. In your body, narrowed blood vessels cause the blood flow to slow and back up into the right side of the heart as it struggles to keep up. This means less blood is able to get pushed through the lungs to pick up oxygen. Because the heart has to work harder to pump blood into the lungs, people with PAH begin to experience symptoms such as chest pain and shortness of breath. Although symptoms help doctors diagnose PAH. They are also a critical element of monitoring PAH over time.

Knowing about the symptoms you experience and when you experience them helps your healthcare provider assess whether your condition is improving, staying the same, or getting worse. This is key to determining the right treatment plan. You are likely familiar with at least some of the PAH symptoms like shortness of breath, a rapid, hard, irregular heartbeat, chest pain, swollen ankles, a swollen abdomen, or even dizziness and fainting. Over time, as the disease progresses, the symptoms get worse and you may find that you cannot do as much physically. It’s important to note that symptoms may not always reflect whether PAH is progressing or how it is affecting your body. Even if your symptoms remain the same, there still may be more you can do to help improve how you feel. Sometimes people with PAH try to ignore their symptoms until they become more extreme, but when it comes to PAH, it’s important to speak with your doctor about how you are doing.

Effectively treating PAH sooner rather than later can make a difference in how quickly your PAH progresses. So it’s important to be your own advocate and to find an experienced PAH doctor. Not all pulmonologists and cardiologists have specialized PAH training, so it’s important to find a PAH doctor who understands each of the available PAH medications.

Things to remember: PAH is a disease of high blood pressure within the blood vessels of the lungs that leads to right heart damage and eventually heart failure. The symptoms that you feel are a reflection of how your heart is struggling and they will not improve without treatment. PAH is a progressive disease, meaning that it will get worse over time, but the rate of progression varies. Be proactive by finding a doctor who specializes in PAH and ask about things you may be able to do now to reduce symptoms and help slow disease progression. I’ll leave you with this tip: Keep a symptom journal. Either on paper, on your computer, on a mobile device. That way you won’t have to try and remember everything that happens between doctor visits. This will help you and your healthcare provider determine whether your PAH symptoms are changing over time and what treatment options may be best for you.

Thank you for watching PAH Basics. Watch the next video from the PAH Initiative video series to learn about working with your PAH doctor to set goals for treatment.

PAH Basics Video

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PAH symptom tracker journal

PAH Symptom Journal

Download this sheet to make it easy to track your symptoms. Knowing your symptoms can help your healthcare provider determine which treatments are right for you.

PAH patient questionnaire

PAH Patient Questionnaire

This 5-question form can help you plan and initiate focused conversations with your healthcare provider.

PAH Doctor Discussion Tool

PAH Doctor Discussion Tool

Use this discussion tool to plan the things you’d like to discuss with your healthcare team. It addresses topics like your symptoms, test results, and treatment options.

PAH and stress relief

10 Simple Ways to Relieve Stress 

Some of the ways to relieve stress are obvious, like yoga. But music, gardening, laughter—and even chewing gum—can help you relax and ease your stress.

PAH low sodium diet

Low-Sodium, PAH-Friendly Diets  

This 1-page guide provides websites full of recipes and tips that can help you cut back on salt. You’ll also learn to understand nutrition labels and find suggestions for those times when you’re dining at a restaurant or with friends.

PAH diet recipes

Healthy Smoothie Recipes

Get more flavor in your diet with nutritious smoothies. These 8 smoothie recipes offer flavors like peanut butter banana, cherry chocolate, and key lime pie.

PAH Initiative glossary of terms

Atrium (right and left)

The upper chambers of the heart. The atria receive blood from the veins, while the ventricles pump blood to the veins. 

Blood vessels

Blood vessels are part of the circulatory system and function to transport blood throughout the body. 


Chronic means ongoing or occurring over an extended time. Chronic diseases generally cannot be prevented by vaccines or cured by medication, nor do they just disappear.  

Disease progression

When a condition gets worse over time, it’s called disease progression.


This test measures the size and shape of the heart. It also measures how well the heart squeezes and relaxes.


One of 3 natural substances produced by small blood vessels in the lungs that helps to keep blood vessels healthy. Endothelin helps contract blood vessels. 

High blood pressure

Also known as hypertension, this is when blood pressure—the force of blood flowing through the blood vessels—is consistently too high. The primary way that high blood pressure causes harm is by increasing the workload of the heart and blood vessels, making them work harder and less efficiently.

Nitric oxide

One of 3 natural substances produced by small blood vessels in the lungs that helps to keep blood vessels healthy. Nitric oxide helps keep blood vessels open.

NT-proBNP/BNP (or BNP blood test)

A test that measures the amount of molecules found naturally in the body. These include the hormone called B-type natriuretic peptide, or BNP, and its precursor, NT-proBNP. When the heart works harder than usual, it releases high levels of BNP. If this test shows high levels of BNP, it means the heart is straining and working harder than normal. The strain may be caused by narrow blood vessels in the lungs due to PAH.

PDE-5 inhibitor

A type of targeted therapy used to treat PH and PAH. PDE-5 is an enzyme found in blood vessel walls. It helps control blood flow to the arteries in the lungs. PDE-5 inhibitors stop PDE-5 from working properly. By stopping PDE-5 from working, PDE-5 inhibitors cause the blood vessels to relax, which increases blood flow to the lungs and lowers blood pressure.


This is a medical term for predicting the likely course of a disease, including whether signs and symptoms will improve, remain stable, or worsen (and how quickly that may happen). Prognosis also can include the likelihood of survival.


One of 3 natural substances produced by small blood vessels in the lungs that helps to keep blood vessels healthy. Prostacyclin helps keep blood vessels open, prevents clotting, and slows the thickening of blood vessels.

Pulmonary arterial hypertension (PAH)

A condition where the blood vessels in the lungs become narrower. This causes the heart to work harder to pump blood to the lungs.

Pulmonary hypertension

A type of high blood pressure that affects arteries in the lungs and the heart. (Pulmonary arterial hypertension is a specific and more serious form of pulmonary hypertension.)  

Right heart catheterization

A procedure that reveals how much blood the heart pumps through the lungs. In addition, it helps determine the severity of PAH. This is currently the only test that can diagnose PAH. 

Risk assessment

Part of the standard guidelines for treating PAH. In a risk assessment, the healthcare provider looks at all test results and other factors to help predict how a patient will be doing over the next 5 years. Healthcare providers use the information from the risk assessment to determine risk status.

Risk status

A designation that healthcare providers assign to patients with PAH based on the results of a risk assessment. Risk status can be low, intermediate, or high. Risk status enables healthcare providers to predict the probability of life expectancy over the next 3 to 5 years.

Ventilation perfusion scan

This 2-part test measures breathing and blood flow in the lungs. The test is used to determine if there are blood clots in the lungs, which can cause high blood pressure.


The lower 2 chambers of the heart. The ventricles receive blood from the atria and pump it to the lungs (right ventricle) or to the entire body (left ventricle).

WHO Functional Class

A system developed by the World Health Organization (WHO) to help classify PAH. The 4 Functional Classes are based on the severity of PAH. 

6-minute walk test

A common test that evaluates how far a patient with PAH can walk in 6 minutes. Normal goals vary for each person, and risk status will affect each patient’s goal. The low-risk goal is walking more than 440 meters in 6 minutes. The 6-minute walk test is the best predictor of how patients will be doing over the next 3 to 5 years.

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