What is the difference between Pulmonary Hypertension (PH) and Pulmonary Arterial Hypertension (PAH)?  There is an important difference between PH & PAH. Pulmonary hypertension is a general term and simply means high blood pressure in the lung. The high blood pressure can be caused by many medical conditions such as diseases of the left heart, chronic lung diseases, sleep apnoea, and blood clots in the lungs. PAH is a specific cause of Pulmonary Hypertension where the arteries of the lungs are directly diseased and become narrowed. It is very important that the exact cause of PH is determined since treatment must be directed at the underlying condition.
What is Pulmonary Arterial Hypertension (PAH)? Pulmonary Arterial Hypertension (PAH) is the medical term for a progressive disease caused by narrowing or tightening (constriction) of the pulmonary arteries that connect the right side of the heart to the lungs. PAH is a serious condition that affects the blood vessels (pulmonary arteries) that carry blood from the heart to the lungs. PAH is the medical term for a progressive disease caused by narrowing or tightening (constriction) of the pulmonary arteries that connect the right side of the heart to the lungs. ​PAH gradually restricts the flow of blood through the lungs. As a result, the pressure in the pulmonary arteries increases. The heart must pump against this increased pressure to maintain blood flow in the lungs and to the rest of the body. Over time, this can affect the heart's ability to work effectively and may eventually lead to heart failure. 



Pulmonary Arterial Hypertension

& Pulmonary Hypertension

The differences and how

it affects your body individually.

Although PAH is still a rare condition, it is a disease that can affect males and females of all ages and ethnic backgrounds. Very rarely, PAH occurs in childhood. This makes early diagnosis very important as treatment can alleviate many of the symptoms associated with pulmonary arterial hypertension, improving people's quality of life.

​Treatment and ongoing management by specialist pulmonary hypertension doctors, nurses, and their healthcare team is vital. People with certain existing medical conditions can also be at a higher risk of developing pulmonary hypertension CLICK (for more info). Currently there is no cure for this serious progressive disease but every year new and improved medications and treatments are being developed which have prolonged and improved the lives ​of those living with this disease.  ​


There  are a great many new and exciting developments in the world of Pulmonary Hypertension. ​With more effective treatments being available people with pulmonary hypertension have the opportunity to manage their disease better, and achieve a higher quality of physical, emotional, and psychological health and well being.  ​(Part of this explanation for PH/PAH was shared with you from the Lung Foundations Better Living Series PAH A Patients Guide.  ​For your own complete guide contact the: There is also a 2019 updated Ebook ready to be downloaded! Click Here

What are the signs and symptoms to look out for?

Many of the symptoms of pulmonary arterial hypertension (PAH) are nonspecific leading to under or misdiagnosis in many patients. It is common to spend more than two years from the time symptoms present to the time of accurate diagnosis.

​This is very concerning since pulmonary arterial hypertension (PAH) is a progressive disease and the more advanced the disease is before treatment the worse the outcomes are for the patient. For this reason, many PAH specialists spend time and energy educating community physicians about signs and symptoms of pulmonary hypertension.

Common symptoms may include one or more of the following:

  • Unexplained prolonged breathlessness or dyspnoea (blue lips or fingertips), Syncope (fainting).​

  • Usually starts with shortness of breath with activities such as walking up inclines or stairs but can progress to breathlessness at rest.

  • Chest pain: This pain can vary from feeling pressure in the chest to stabbing pain and is very individualized.

  • Dizziness: Feeling light headed or dizzy with activity.

  • Fainting/Syncope: This is a very concerning symptom that should be paid close attention. Many times the fainting happens when a pulmonary arterial hypertension (PAH) patient bends down with their head lowered to pick something up. A known pulmonary hypertension patient should always report an episode of fainting or near fainting to their PAH specialist.

  • Chronic fatigue: Not being able to do the same activities as previously able to do, or having to take breaks to complete usual chores such as making the bed or vacuuming the floor.

  • Swelling in the ankles or oedema: Fluid accumulates in the body because the heart is strained and cannot efficiently pump. The fluid generally settles in the feet, ankles, and legs as they are the most dependent part of the body but swelling can also be noticed in the abdomen and hands.

  • Many other diseases such as congestive heart failure or diastolic heart failure have very similar symptoms of pulmonary hypertension. Diagnosing pulmonary arterial hypertension (PAH) involves ruling out other causes for these symptoms by doing non-invasive testing such as pulmonary function testsCT scans, and echocardiograms before proceeding to the more invasive right heart catheterisation.

Symptoms will become worse over time.​ The longer you go undiagnosed the more the disease will progress.

Early treatment is essential. Even with mild pulmonary hypertension you need to be monitored regularly.

What Classification are you in?

  • Where do I fit into the pulmonary hypertension classification table?

  • Do I know what type of pulmonary hypertension I have? 

  • What's my exercise capacity?

  • What group do I fit into?

  • Find out more here with the updated information from the

  • World Health Organisation (WHO) classification table.

Classification for Pulmonary Hypertension
​Classifying Pulmonary Hypertension through Exercise Capacity and Symptoms

There are four functional classes that are used to rate how ill PH patients are.  Currently, the World Health Organization or WHO class system is used to describe these patients. 

It is important to distinguish WHO functional class from WHO group. ​The WHO group system classifies what type of pulmonary hypertension a patient has while the WHO functional class system gives information about how affected they are by their disease. ​

The higher the class the more severe the disease and the greater the urgency for the patient to be accurately diagnosed and started on therapy for pulmonary hypertension.

It is important to treat all classes of pulmonary arterial hypertension (PAH) as the disease is progressive, meaning it will get worse over time without treatment.

WHO Class I
No symptoms of pulmonary arterial hypertension with exercise or at rest.  It is rare for a patient to be diagnosed while still a class I.  Patients that are being screened because of high risk factors for developing pulmonary hypertension, such as patients with scleroderma or family history of PAH, may rarely be diagnosed as class I. More often this classification is used to describe patients that have demonstrated a substantial response to therapy that were once a class II or III but have improved to a class I.

WHO Class II
Class II: No symptoms at rest but uncomfortable and short of breath with normal activity such as climbing a flight of stairs, grocery shopping, or making the bed.

Class III: May not have symptoms at rest but activities greatly limited by shortness of breath, fatigue, or near fainting. Patients in this class have a difficult time doing normal chores around the house and have to take breaks while doing activities of daily living.

WHO Class IV
Class IV: Symptoms at rest and severe symptoms with any activity. Patients in this class may faint especially while bending over with their heads lowered. Most patients in this class are also volume overloaded with edema in their feet and ankles from right heart failure.

The five groups of pulmonary hypertension today are

World Health Organisation (WHO) Classification

Pulmonary hypertension is a severe, rare lung disease characterized by high blood pressure in the pulmonary arteries, which deliver blood from the heart to the lungs. The high pressure causes the heart to work harder to pump blood. This, in turn, causes strain that can lead to the heart becoming larger and weaker, and eventually result in right heart failure. There is a wide range of potential causes for pulmonary hypertension, and these can affect the symptoms, treatment, and prognosis of the disease.To produce, maintain, and implement international health information standards, the World Health Organization (WHO) defined a classification for pulmonary hypertension diagnosis in 1973, based on the cause of the disease. This has seen multiple revisions, reflecting advances in disease understanding, with the most recent being presented in 2013 at the Fifth World Symposium on Pulmonary Hypertension in Nice, France.

Aims of the classification 

The international classification of diseases (ICD) is created by the organization and comprises a standard diagnostic tool for physicians, nurses, other providers, researchers, health information managers and coders, health information technology workers, policy-makers, insurers, and patient organizations. To determine the classification of pulmonary hypertension, WHO analyzed the general health situation of patients, as well as the disease incidence and prevalence.The WHO classification is used for numerous purposes, including records, death certificates, information storage, diagnosis retrieval, national mortality and morbidity statistics, reimbursement, resource allocation, and other clinical, epidemiological and quality purposes. The organization expects the classification to help fight the disease.

The classification

In 1973, pulmonary hypertension was classified into only two groups. These were “primary pulmonary hypertension” if the cause of the disease was known, or “secondary pulmonary hypertension” if the cause could not be identified. Secondary pulmonary hypertension also was called “idiopathic pulmonary hypertension.”Now the classification has been expanded to five groups, to emphasize the importance of the underlying cause of the disease. This reflects our increased knowledge of what can cause pulmonary hypertension, along with what impact this can have on disease progression and required treatment.

Group 1: pulmonary arterial hypertension
Group 1 includes pulmonary hypertension is associated with the narrowing of the small blood vessels in the lungs.

It also is called pulmonary arterial hypertension (PAH) and includes cases where the underlying cause of the narrowing is not known (idiopathic pulmonary hypertension).​  There are multiple other subgroups in group 1, including: Familial, or heritable pulmonary hypertension, PAH caused by certain drugs or toxins, PAH associated with other conditions such as connective tissue diseases like scleroderma or lupus, congenital heart problems, high blood pressure in the liver, HIV, certain infections like schistosomiasis, and sickle cell anemia. Group 1 also may be caused by rare blood conditions, like pulmonary veno-occlusive disease (PVOD) or pulmonary capillary hemangiomatosis (PCH), and a type of pulmonary hypertension present in babies called persistent pulmonary hypertension of the newborn (PPHN).

Group 2: pulmonary hypertension due to left heart disease
Group 2 refers to pulmonary hypertension caused by left heart disease.

Long-term problems with the left side of the heart can lead to changes in the pulmonary arteries and cause pulmonary hypertension.
This may include: Left ventricular systolic dysfunction, when the heart cannot pump blood effectively. Left ventricular diastolic dysfunction, when the heart cannot properly relax to allow enough blood to flow in. Valvular disease, when the valves of the left side of the heart are allowing blood to leak. Congenital heart defects (heart defects from birth), which can lead to problems with blood flowing in or out of the heart.

​Group 3: pulmonary hypertension due to lung disease and/or chronic hypoxia
Group 3 includes pulmonary hypertension resulting from lung diseases or shortage of oxygen in the body (hypoxia).

The common diseases associated with group 3 pulmonary hypertension are: Chronic obstructive pulmonary disease (COPD), Interstitial lung disease Sleep-disordered breathing, a group of diseases that affect breathing during sleep like obstructive sleep apnea (OSA), Chronic high-altitude exposure, Lung developmental abnormalities, Alveolar hypoventilation disorders

Group 4: pulmonary hypertension due to blood clots in the lungs
Group 4 refers to pulmonary hypertension caused by blood clots obstructing the pulmonary arteries.

This also can be referred to as chronic thromboembolic pulmonary hypertension (CTEPH). Clots are the body’s response to bleeding and injuries, but can harm the heart and lungs when they occur without an apparent cause. Pulmonary emboli are blood clots that travel to the lungs, and pulmonary thrombosis are clots that are formed in the lungs, which can block the pulmonary arteries.

​Group 5: pulmonary hypertension due to blood and other disorders
Group 5 is the last category and includes other less-common causes that do not fit into any of the other four groups. 

These are widely split into four categories: Blood disorders, such as some types of anemia. Systemic disorders, such as sarcoidosis (a condition that results in inflammation of different organs like the lungs and lymph nodes) and histiocytosis (a rare disorder that causes scarring). Metabolic disorders, such as glycogen storage diseases and thyroid disorders. Other disorders, such as chronic kidney failure or tumors obstructing pulmonary arteries.

CLICK HERE  for the Classification Table in full from the (World Health Organisation - WHO)

Shared with you through www.pulmonaryhypertensionnews.com - Information research supplied by Patricia Silva PhD

and fact checked by Ozge Ozkaya - please refer to the original content online for more information.

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