Echocardiographic evaluation for phenotyping pulmonary hypertension in COPD. A review of the literature and a proposal for clinical practice

Abstract

Background. Chronic obstructive pulmonary disease (COPD) is a complex and heterogeneous lung condition characterised by chronic respiratory symptoms (dyspnoea, cough, sputum production) due to an inflammatory state affecting the airways, lung parenchyma and pulmonary vasculature. When the inflammatory state is particularly severe, the damage to the lung tissue leads to an imbalance between ventilation and perfusion (V/Q) in the alveoli and to hypoxemia, a factor that increases remodeling of the vascular bed, vascular resistance, worsening hypoxemia and pulmonary hypertension, a common complication that in COPD  is usually mild.

Recent cluster analysis within the COPD population  has identified a novel phenotyping of patients characterized by moderate airway obstruction, marked reduction in diffusing capacity for carbon monoxide and severe hypoxemia with normal P_aCO₂  and severe pulmonary hypertension, which is considered “out of proportion” and profound cardiopulmonary impairment.

So, screening for pulmonary hypertension is more necessary than ever in clinical practice, not only to assess pulmonary vascular damage, but also to intercept COPD that may have more vascular than ventilatory damage, or both; or to exclude COPD as a cause due to left ventricular failure.

 Methodology: We reviewed the literature data on the use of echocardiography to screen for pulmonary hypertension in patients with COPD of all severities. Opinions on the reliability of the method vary and are sometimes in contrast to the reliability of the eco-Doppler method for measuring pulmonary pressure in COPD, as the detection of pressure values is often in contrast to the chest conformation resulting from airway pathology. Right heart catheterisation remains the gold standard for the diagnosis of pulmonary hypertension, but the main drawback of the procedure is indeed its invasive nature, which carries some risks and cannot be performed on a large scale, especially in advanced COPD, which is often associated with severe comorbidities. Therefore, based on our experience, we have made a selection within the framework of the entire echocardiographic methodology and suggest a 4-step echocardiographic pathway with multiple parameters, including M-mode, 2D, pulsed-wave (PW) and continuous-wave (CW) colour Doppler, to define the presence of pulmonary hypertension, determine the severity of disease and phenotype of pulmonary vascular COPD or cardiogenic disease that could easily escape clinical observation, and provide support in screening for pulmonary hypertension for those assessing lung pathophysiology function in patients with COPD. Conclusion: Considering the limitations, Doppler echocardiography is a useful method for measuring pulmonary pressure and determining the underlying anatomical and functional cardiac abnormalities in patients with COPD. Right heart catheterization is necessary to accurately measure (or rule out) the presence of pulmonary hypertension; however, establishing a good correlation does not mean that one test can accurately replace another, but rather the combination and appropriate use of multiple modalities. Doppler echocardiography is a non-invasive, easily accessible and invaluable screening tool for the assessment and further management of pulmonary hypertension and represents a compromise between accuracy, safety, simplicity and cost. Doppler echocardiography and right heart catheterization, which complement each other, could lead to the highest level of care, especially for the COPD population, which may escape clinical and instrumental assessment of severe pulmonary hypertension. We believe that the clinician today faces the challenge of achieving ever better diagnostic and treatment goals and reducing the invasiveness of procedures to improve diagnostics. Therefore, Doppler echocardiography should be widely used not only in the diagnosis and treatment of heart disease, but also in lung diseases, especially COPD, the most common lung disease. The physician dealing with respiratory diseases must have sufficient knowledge of Doppler echocardiography in daily clinical practice and basic skills to assess or rule out, to prevent or reduce the escape of severe pulmonary hypertension in COPD and to avoid leaving the diagnosis to other specialists who are less involved in respiratory pathology and may pay less attention to the realities of COPD.