Table 1.

World Health Organization (WHO) classification schemes for pulmonary hypertension (PH) and functional class (FC). The examples given for each WHO PH group are not comprehensive but offer representations of disease processes in each category. The patient in this report is group 1 PH with FC IV.

Category	Characteristics
All groups of PH	mPAP of ≥25 mmHg at rest, PVR of >240 Dynes-sec/cm5, PAWP ≤15 mmHg (except for group 2 PH where PAWP ≥15 mmHg).
Group 1 PH	Pulmonary arterial hypertension (PAH). It includes idiopathic PAH, PAH from genetic mutations, medications, HIV, portal hypertension, congenital heart disease, and schistosomiasis. It also includes PAH associated with connective tissue diseases such as SLE and systemic sclerosis.
Group 2 PH	Pulmonary venous hypertension (left-sided heart disease/failure).
Group 3 PH	PH owing to chronic lung diseases and/or hypoxemia (e.g., chronic obstructive pulmonary disease, sleep disordered breathing, and interstitial lung diseases).
Group 4 PH	PH from chronic thromboembolic disease.
Group 5 PH	PH occurring in several miscellaneous conditions whose association with PH is poorly understood (e.g., sarcoidosis, lymphangioleiomyomatosis, and Langerhans cell histiocytosis).
FC I	No symptoms with ordinary physical activity.
FC II	Fatigue, dyspnea, chest pain, or syncope with ordinary physical activity.
FC III	Symptoms that develop with less than ordinary physical activity.
FC IV	Symptoms with any physical activity, or while at rest.