What is “pulmonary hypertension”?

The term “pulmonary hypertension” refers to an increase in blood pressure in the arteries of the lungs. Symptoms of pulmonary hypertension include shortness of breath, syncope, tiredness, chest pain and swelling of the legs. The European Society for Cardiology (ESC), and European Respiratory Society (ERS), “Guidelines for the diagnosis and treatment of pulmonary hypertension”, officially presented for the first time on August 26, 2022 at the ESC Annual Congress, have reconsidered the previous haemodynamic definition of pulmonary hypertension and fixed the cut off point at a mean pulmonary arterial pressure (PAPm) of >20 mmHg. You will find a list of the main other changes with respect to the 2015 guidelines in Chapter 2.1. of the guidelines.

The main focus of the PH-KSP is on the rare forms

The main focus of the Pulmonary Hypertension Knowledge Sharing Platform is on the conditions included in Group 1 of the WHO classification, pulmonary arterial hypertension, PAH, and Group 4, pulmonary hypertension associated with pulmonary artery obstructions (including chronic thromboembolic pulmonary hypertension, CTEPH).

Pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension are rare conditions for which medical therapies and surgery have been developed. They are characterised by different risk factors and medical therapies but research indicates that there may be possible common mechanisms behind the two, including endothelial cell dysfunction and distal pulmonary artery remodelling.

The other three WHO groups are pulmonary hypertension associated with left heart disease (Group 2), pulmonary hypertension associated with lung diseases and/or hypoxia (Group 3) and pulmonary hypertension with unclear and/or multifactorial mechanisms (Group 5).

This table summarizes the five Pulmonary Hypertension Groups. Photo credit: European Heart Journal, Volume 43, Issue 38, 7 October 2022, Pages 3618–3731, https://doi.org/10.1093/eurheartj/ehac237 Published 26 August 2022.

Living with pulmonary hypertension

Despite the considerable progress in the field over past decades living with pulmonary hypertension remains challenging and patients have many unmet needs, see the dedicated section at this link and look up the resources included in the website at the Find information page.

Pulmonary arterial hypertension

Pulmonary arterial hypertension is divided into:

  • 1.2 Heritable
  • 1.3 Associated with drugs and toxins
  • 1.4 Associated with:
    • 1.4.1 Connective tissue disease
    • 1.4.2 HIV infection
    • 1.4.3 Portal hypertension
    • 1.4.4 Congenital heart disease
    • 1.4.5 Schistosomiasis
  • 1.5 PAH with features of venous/capillary (PVOD/PCH) involvement
  • 1.6 Persistent PH of the newborn

Pulmonary arterial hypertension is classified within Group 1 of the current pulmonary hypertension classification. It is a progressive disease of the small pulmonary arteries, with increasing mean pulmonary vascular resistance eventually leading to right heart failure. Initial diagnosis of pulmonary arterial hypertension can be difficult as patients often present with non-disease-specific symptoms such as breathlessness, fatigue, peripheral oedema, chest pain during exertion, light headedness, syncope and abdominal distension. The disease is heterogeneous: idiopathic pulmonary arterial hypertension is sporadic, without any familial history of pulmonary arterial hypertension or known triggering factor, but pulmonary arterial hypertension can also be heritable, induced by drugs or toxins, or associated with conditions such as connective tissue disease, congenital heart disease, portal hypertension, HIV infection or schistosomiasis. Pulmonary arterial hypertension is a rare disease with an estimated incidence and prevalence of ∼6 and 48–55 cases/million adults, respectively (data from ESC/ERS guidelines, section 4, Epidemiology).

Thanks to the introduction of pulmonary arterial hypertension-specific therapies and better disease management, quality of life and survival have improved considerably, but in many cases lung or heart-lung transplant remain the only option for end stage disease.

This image shows how in pulmonary arterial hypertension the walls of the pulmonary arteries become thicker (diagram on right), which makes it harder for the blood to pump through them (diagram on left shows normal flow). Over time the right side of the heart becomes weaker and this in turn may lead to heart failure. Photo credit: Shutterstock

Chronic thromboembolic pulmonary hypertension

Chronic thromboembolic pulmonary hypertension is classified within Group 4 of the current official pulmonary hypertension classification. It is characterised by organised thromboembolic material (clots) and by altered vascular remodelling. These changes may lead to pulmonary hypertension and, ultimately, to right heart failure. One of the novelties introduced by the 2022 European Society for Cardiology (ESC) and European Respiratory Society (ERS) “Guidelines for the diagnosis and treatment of pulmonary hypertension”, is a treatment algorithm which includes a multimodal approach of combinations of pulmonary endarterectomy surgery (PEA), balloon pulmonary angioplasty (BPA), and medical therapies to target the mixed anatomical lesions: proximal, distal, and microvasculopathy. Medical therapies include the soluble guanylate cyclase stimulator riociguat and subcutaneous treprostinil (see section on pulmonary arterial hypertension-specific therapies for more details). Lifelong therapeutic anticoagulation is recommended for patients with chronic thromboembolic pulmonary hypertension, as recurrent pulmonary thromboembolism accompanied by insufficient clot resolution, are key pathophysiological features of this disease. Although the exact prevalence and incidence are unknown, data suggest that chronic thromboembolic pulmonary hypertension may occur in about 5 individuals per million population per year.


“2022 ESC/ERS Guidelines for the diagnosis and treatment of pulmonary hypertension”, Marc Humbert, Gabor Kovacs, Marius M Hoeper, Roberto Badagliacca, Rolf M F Berger, Margarita Brida, Jørn Carlsen, Andrew J S Coats, Pilar Escribano-Subias, Pisana Ferrari, Diogenes S Ferreira, Hossein Ardeschir Ghofrani, George Giannakoulas, David G Kiely, Eckhard Mayer, Gergely Meszaros, Blin Nagavci, Karen M Olsson, Joanna Pepke-Zaba, Jennifer K Quint, Göran Rådegran, Gerald Simonneau, Olivier Sitbon, Thomy Tonia, Mark Toshner, Jean Luc Vachiery, Anton Vonk Noordegraaf, Marion Delcroix, Stephan Rosenkranz, European Heart Journal, January 26, 2022

“Pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension: pathophysiology”, Marc Humbert, European Respiratory Review 2010 Mar;19(115):59-63

“Chronic thromboembolic pulmonary hypertension”, Nick H. Kim, Marion Delcroix, Xavier Jais, Michael M. Madani, Hiromi Matsubara, Eckhard Mayer, Takeshi Ogo, Victor F. Tapson, Hossein-Ardeschir Ghofrani, David P. Jenkins, European Respiratory Journal 2019 53:

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