Pulmonary Hypertension

Types and Characteristics of Pulmonary Hypertension

• WHO Group 1 refers to pulmonary arterial hypertension (PAH), caused by narrowed, thickened, or stiff arteries in the lungs, leading to increased resistance and restricted blood flow.
• WHO Group 2 includes pulmonary hypertension due to left heart disease, resulting in increased pressure in the lungs due to heart inefficiencies, and is the most common form of PH.
• WHO Group 3 involves pulmonary hypertension due to lung disease, including conditions such as COPD, emphysema, and sleep apnea, leading to tightened arteries in the lungs.
• WHO Group 4 is pulmonary hypertension due to chronic blood clots in the lungs, known as chronic thromboembolic pulmonary hypertension (CTEPH), which can potentially be cured through surgery.
• WHO Group 5 is pulmonary hypertension due to unknown causes, secondary to conditions such as sarcoidosis, sickle cell anemia, and certain metabolic disorders.
• Pulmonary arterial hypertension (PAH) within Group 1 can occur idiopathically, heritably, or in association with other medical conditions, and if left untreated can lead to right heart failure and death.
• PH-targeted therapies are available for WHO Group 1 to relieve symptoms, improve quality of life, and slow down disease progression, while patients in Groups 2 and 3 can benefit from treating underlying heart and lung diseases.
• In PAH, arteries become thick and stiff, limiting blood flow and increasing resistance, potentially leading to right heart failure and death if untreated.
• WHO Group 2 PH can lead to severe PAH with plexiform lesions and advanced vascular lesions and thrombi formation.
• Group 1 PAH has a prevalence of 15 to 50 per million globally, with common causes including idiopathic, heritable, and drug-induced factors, and rarer causes including HIV and portal hypertension.
• Randomized trials have shown the effectiveness of vasodilator agents in treating Group 1 PAH, characterized by precapillary PH with specific hemodynamic parameters.
• The incidence and prevalence of PH in the USA and Europe are 6 and 48–55 cases/million adults, respectively, with IPAH being the most common subtype, affecting four times more females than males.