Figures
- FIGURE 1
Diagnostic algorithm for patients with chronic thromboembolic pulmonary hypertension (CTEPH) [14, 19]. PH: pulmonary hypertension; PFT: pulmonary function test; TTE: transthoracic echocardiography; HRCT: high-resolution computed tomography; V′/Q′: ventilation/perfusion; PAP: pulmonary artery pressure; PCWP: pulmonary capillary wedge pressure; PVR: pulmonary vascular resistance; CT: computed tomography; MRI: magnetic resonance imaging. #: riociguat is currently the only licensed therapy for CTEPH.
- FIGURE 2
Diagnostic imaging of distal chronic thromboembolic pulmonary hypertension lesions. a) Ventilation/perfusion scintigraphy. b) Conventional pulmonary angiography. c) Computed tomography pulmonary angiography.
Tables
- TABLE 1
Summary of techniques used in the diagnosis of chronic thromboembolic pulmonary hypertension (CTEPH)
Technique Advantages Potential disadvantages Ventilation/perfusion (V′/Q′) scan Essential for diagnosing CTEPH Can give intermediate probability result, Sensitivity >96% which cannot rule out CTEPH Negative result rules out CTEPH May underestimate the burden Can distinguish between large-vessel occlusive and small-vessel pulmonary vascular disease of vascular obstruction Less radiation exposure than CTPA Less likely than other techniques to detect incidental findings Avoids potential problems with intravenous contrast Conventional pulmonary angiography (CPA) Can be combined with RHC to provide imaging and haemodynamic information Invasive Right heart catheterisation (RHC) Mandatory in diagnosing CTEPH Invasive Essential measurements of mean arterial pressure and pulmonary capillary wedge pressure Information on disease severity, right heart function, mixed venous oxygen saturation Computed tomography pulmonary angiography (CTPA) Noninvasive Sensitivity 51% (lower than V′/Q′ scan) High-resolution images Chronic disease looks different to acute PE: New scanners can provide multi-planar and three-dimensional reconstructions of the vascular tree More anatomical detail than MRI: information about vascular wall thickness and surrounding structures not appreciable with CPA No need for direct catheter access additional training required Risk of false positives (e.g. pulmonary artery sarcoma) May miss disease in distal segmental or subsegmental vessels May miss inoperable patients who could Can reveal associated findings, e.g. bronchial artery collaterals, mosaic perfusion patterns begin medical therapy May underestimate clot burden Lower cost than CPA Rapid acquisition, even in breathless patients DECTA has improved the detection of distal CTEPH Cardiac magnetic resonance imaging (MRI) Noninvasive, no radiation exposure Limited availability, expensive, Morphological, functional and anatomical assessment of heart and pulmonary circulation time consuming Useful for repeat studies, e.g. pre- and post-operative monitoring Phase-contrast MRI can quantify blood flow and peak velocity in the main pulmonary artery Contrast-enhanced magnetic resonance angiography has similar sensitivity to CTPA PE: pulmonary embolism; DECTA: dual-energy computed tomography angiography. Information from [14, 17, 18].
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