The World Health Organization (WHO) classifies pulmonary hypertension, including pulmonary arterial hypertension (PAH), into different groups based on the underlying causes.
Group 1: Pulmonary arterial hypertension (PAH): elevated blood pressure in the pulmonary arteries.
Subtypes include idiopathic PAH (unknown cause), heritable PAH (genetic), and PAH associated with other conditions.
Group 2: Pulmonary hypertension associated with left heart disease: high blood pressure in the lungs due to problems in the left side of the heart, such as heart failure.
Group 3: Pulmonary hypertension associated with lung diseases and/or hypoxia: pulmonary hypertension linked to chronic lung diseases like COPD or conditions causing low oxygen levels in the blood.
Group 4: Chronic thromboembolic pulmonary hypertension (CTEPH): caused by blood clots in the pulmonary arteries, leading to increased pressure.
Group 5: Pulmonary hypertension with unclear and/or multifactorial mechanisms: pulmonary hypertension associated with various conditions that don't fit into the other groups.
This classification helps doctors identify the cause of pulmonary hypertension and determine the most suitable treatment. It's a way to organize the different types of pulmonary hypertension based on what's causing it.