Pulmonary Hypertension

Key Features

Essentials of Diagnosis

• Defined as pulmonary artery (PA) systolic pressure > 30 mm Hg or mean PA pressure > 25 mm Hg

• Multiple potential etiologies must be considered, including both pulmonary and cardiac

• Idiopathic (primary) pulmonary hypertension (PH) most frequently occurs in younger women

• Dyspnea, chest pain, exertional syncope

• Narrow splitting of second heart sound with loud pulmonary component; findings of right ventricular (RV) hypertrophy and heart failure in advanced disease

• Enlarged central pulmonary arteries on chest radiograph

• ECG evidence of RV strain or hypertrophy and right atrial (RA) enlargement

• Two-dimensional echocardiography with Doppler flow echocardiography is often diagnostic, showing elevated RV systolic pressure; right heart catheterization is confirmatory

General Considerations

• During the 2019 Sixth World Symposium on Pulmonary Hypertension, the definition of PH was changed

• PH was defined by a mean PA pressure of 20 mm Hg with a pulmonary vascular resistance (PVR) of ≥ 3 Wood units and then categorized into three groupings:

  • Precapillary PH: Mean pulmonary arterial pressure (PAP) > 20 mm Hg, PVR ≥ 3.0 Wood units, pulmonary capillary wedge pressure (PCWP) ≤ 15 mm Hg

  • Isolated post-capillary PH: Mean PAP > 20 mm Hg, PVR < 3.0 Wood units, PCWP > 15 mm Hg

  • Combined pre- and post PH: Mean PAP > 20 mm Hg, PVR ≥ 3.0 Wood units, PCWP > 15 mm Hg

• The World Health Organization (WHO)/New York Heart Association (NYHA) functional class classification of PH includes the following 5 groups:

  • Group I (pulmonary arterial hypertension [PAH]) with pulmonary vasculopathy, PH, and elevated PVR in the absence of other diseases of the lungs or heart

  • This group includes

    • Idiopathic (formerly primary) PAH

    • Heritable PAH

    • Drugs and toxins-induced PAH (anorexigenic agents (aminorex fumarate, fenfluramine, dexfenfluramine), rapeseed oil, L-tryptophan, amphetamines and cocaine)

    • PAH associated with HIV infection, portal hypertension, connective tissue disorders (most commonly systemic sclerosis), congenital heart disease (Eisenmenger syndrome), schistosomiasis, sickle cell disease

    • Obstruction of the pulmonary venous circulation (pulmonary veno-occlusive disease and capillary hemangiomatosis)

  • Group II (pulmonary venous hypertension due to left heart disease): Includes

    • Left ventricular (LV) systolic or diastolic dysfunction

    • Valvular heart disease

  • Group III (PH due to lung disease or hypoxemia): Causes include

    • Advanced obstructive and restrictive lung disease including chronic obstructive pulmonary disease (COPD)

    • Interstitial lung disease

    • Pulmonary fibrosis

    • Sleep-disordered breathing

    • Alveolar hypoventilation syndromes

    • High altitude exposure

  • Group IV (PH due to pulmonary arterial obstruction): This group includes

    • Chronic thromboembolic PH (primarily)

    • Other causes of pulmonary arterial obstructions, such as sarcoma, metastatic malignancies, and congenital pulmonary artery stenosis

  • Group V (PH secondary with unclear or multifactorial mechanisms): These patients have PH secondary to

    • Hematologic disorders (eg, chronic hemolytic anemia, sickle cell anemia, myeloproliferative disorders, splenectomy)

    • Systemic disorders (eg, sarcoidosis, vasculitis, pulmonary Langerhans cell histiocytosis, neurofibromatosis type 1)

    • Metabolic disorders (eg, glycogen storage disease, Gaucher disease, thyroid ...