Classification of Pulmonary Hypertension 

Pulmonary hypertension (PH) is classified according to how severe it is. This helps medical staff to understand how much PH is affecting someone. It also helps medical staff find the right treatment for people with PH.  The system that is used to classify PH was developed by the World Health Organization (WHO). It is based on how much exercise people with PH can do before they start to notice symptoms such as shortness of breath.  

World Health Organisation (WHO) Classification of PH based on exercise

Clinical Classification of Pulmonary Hypertension 

Glossary -:  PAH: pulmonary arterial hypertension; PVOD: pulmonary veno-occlusive disease;  PCH: pulmonary capillary haemangiomatosis;  LVEF: left ventricular ejection fraction.

Group 1 PAH

1.1    Idiopathic (IPAH)
1.2    Heritable (HPAH) (previously known as Familial (FPAH)
1.3    Drug and toxin induced PAH 

Updated classification of drugs and toxins associated with PAH

Simplifying the characterisation of PAH associated with drugs and toxins into two subgroups to help physicians to identify drugs requiring specific surveillance was made in a proposal at the World Health Organisation (WHO) PH Symposium in Nice, France in 2018. 

“Definite association” includes drugs with data based on outbreaks, epidemiological case–control studies or large multicentre series. “Possible association” is suggested by multiple case series or cases with drugs with similar mechanisms of action. Based on recent data, the association of PAH with two drugs and toxins (amphetamines/methamphetamines and dasatinib) is now considered definite.

(Ref: European Respiratory Journal https://erj.ersjournals.com/content/early/2018/10/11/13993003.01913-2018 )

1.4       PAH associated with (APAH) (previously known as Secondary (SPAH)
1.4.1    Connective tissue diseases
1.4.2    HIV infection
1.4.3   Portal hypertension
1.4.4    Congenital heart disease

1.4.5    Schistosomiasis
1.5       PAH long-term responders to calcium channel blockers 

Definitions of acute and long-term response

PAH: pulmonary arterial hypertension; mPAP: mean pulmonary arterial pressure; CCB: calcium channel blocker. #: nitric oxide (10–20 ppm) is recommended for performing vasoreactivity testing, but i.v. epoprostenol, i.v. adenosine or inhaled iloprost can be used as alternatives.

1.6    PAH with overt features of venous/capillaries (PVOD/PCH) involvement 

Signs evocative of venous and capillary (pulmonary veno-occlusive disease/pulmonary capillary haemangiomatosis) involvement

DLCO: diffusing capacity of the lung for carbon monoxide; HRCT: high-resolution computed tomography; PAH: pulmonary arterial hypertension.

1.7    Persistent PH of the newborn syndrome

Group 2 PH due to left heart disease

2.1    PH due to heart failure with preserved LVEF
2.2   PH due to heart failure with reduced LVEF
2.3    Valvular heart disease
2.4   Congenital/acquired cardiovascular conditions leading to post-capillary PH

Group 3 PH due to lung diseases and/or hypoxia

3.1   Chronic obstructive disease
3.2   Restrictive lung disease
3.3   Other lung disease with mixed restrictive/obstructive pattern
3.4   Hypoxia without lung disease
3.5    Developmental lung disorders

Group 4 PH due to pulmonary artery obstructions

4.1    Chronic thromboembolic PH
4.2    Other pulmonary artery obstructions

Pulmonary hypertension (PH) due to other pulmonary artery obstructions

Group 5 PH with unclear and/or multifactorial mechanisms

5.1   Hematologic disorders
5.2    Systemic and metabolic disorders
5.3    Others
5.4    Complex congenital heart disease

Pulmonary hypertension with unclear and/or multifactorial mechanisms