Open AccessThe WHO Classification of Pulmonary Hypertension: A Case‐Based Imaging Compendium
Author(s) -
Ryan John J.,
Thenappan Thenappan,
Luo Nancy,
Ha Thanh,
Patel Amit R.,
Rich Stuart,
Archer Stephen L.
Publication year - 2012
Publication title -
pulmonary circulation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.791
H-Index - 40
ISSN - 2045-8940
DOI - 10.4103/2045-8932.94843
Subject(s) - medicine , pulmonary hypertension , gold standard (test) , cardiology , pulmonary artery , magnetic resonance imaging , radiology , cardiac imaging , positron emission tomography , cardiac catheterization , etiology , cardiac magnetic resonance imaging , hemodynamics , perfusion scanning , perfusion
Pulmonary hypertension (PH) is defined as a resting mean pulmonary artery pressure greater than 25 mmHg. The World Health Organization (WHO) classifies PH into five categories. The WHO nomenclature assumes shared histology and pathophysiology within categories and implies category‐specific treatment. Imaging of the heart and pulmonary vasculature is critical to assigning a patient's PH syndrome to the correct WHO category and is also important in predicting outcomes. Imaging studies often reveal that the etiology of PH in a patient reflects contributions from several categories. Overlap between Categories 2 and 3 (left heart disease and lung disease) is particularly common, reflecting shared risk factors. Correct classification of PH patients requires the combination of standard imaging (chest roentgenograms, ventilation‐perfusion scans, echocardiography, and the 12‐lead electrocardiogram) and advanced imaging (computed tomography, cardiac magnetic resonance imaging, and positron emission tomography). Despite the value of imaging, cardiac catheterization remains the gold standard for quantification of hemodynamics and is required before initiation of PH‐specific therapy. These cases illustrate the use of imaging in classifying patients into WHO PH Categories 1–5.