Diagnosis and management of pulmonary hypertension related to chronic respiratory disease

Abstract

Pulmonary hypertension (PH) is a recognised and significant complication of chronic lung disease (CLD) and hypoxia (referred to as group 3 PH) that is associated with increased morbidity, decreased quality of life and worse survival. The prevalence and severity of group 3 PH varies within the current literature, with the majority of CLD-PH patients tending to have non-severe disease. The aetiology of this condition is multifactorial and complex, while the prevailing pathogenetic mechanisms include hypoxic vasoconstriction, parenchymal lung (and vascular bed) destruction, vascular remodelling and inflammation. Comorbidities such as left heart dysfunction and thromboembolic disease can further confound the clinical picture. Noninvasive assessment is initially undertaken in suspected cases (e.g. cardiac biomarkers, lung function, echocardiogram), while haemodynamic evaluation with right heart catheterisation remains the diagnostic gold standard. For patients with suspected severe PH, those with a pulmonary vascular phenotype or when there is uncertainty regarding further management, referral to specialist PH centres for further investigation and definitive management is mandated. No disease-specific therapy is currently available for group 3 PH and the focus of management remains optimisation of the underlying lung therapy, along with treating hypoventilation syndromes as indicated.

FIGURE 1

Processes involved in the pathophysiology of pulmonary hypertension in chronic lung disease and hypoxia. RA: right atrium; RV: right ventricle; LA: left atrium; LV: left ventricle.

FIGURE 2

Diagnostic algorithm for the investigation of pulmonary hypertension (PH) in patients with chronic lung disease (CLD). BNP: brain natriuretic peptide; TFT: thyroid-function tests; AI: autoimmune screen; CXR: chest radiography; HRCT: high-resolution computed tomography; CTPA: computed tomography pulmonary angiogram; Vʹ/Qʹ scan: ventilation/perfusion scan; MRI: magnetic resonance imaging; USS: ultrasound scan; RHC: right heart catheterisation; mPAP: mean pulmonary artery pressure; PAWP: pulmonary artery wedge pressure; PVR: pulmonary vascular resistance; WU: Wood units.