Echocardiographic Screening for PH in CHD: Thinking Outside the Box (Excerpt)
Andrew Constantine, MBBS; Konstantinos Dimopoulos, MD, PhD; Robin Condliffe, MD; Robert Tulloh, MD; Paul Francis Clift, MD

PH in CHD - Pulmonary hypertension (PH) is not uncommon in adults with congenital heart disease (CHD), with a prevalence of 4.2%.¹ It can significantly affect patients' quality of life and increase their morbidity and mortality.^2,3 Hence, early diagnosis and appropriate management are essential for limiting symptoms and improving outcomes. Pulmonary arterial hypertension (PAH) associated with CHD belongs to group 1 of the international PH classification, characterized by pre-capillary PH, where there is a pulmonary artery wedge pressure (PAWP) ≤15 mmHg. There are 4 major types: Eisenmenger syndrome, PAH associated with prevalent left-to-right shunts, PAH with small/coincidental defects, and PAH after defect repair.^4,5 Even within these 4 types, there is significant variation according to the underlying anatomy and the type of prior interventions. Group 2 PH, distinguished by post-capillary hemodynamics (PAWP >15 mmHg), is commonly encountered as a result of systemic ventricular dysfunction or left-sided obstructions, such as mitral stenosis. Moreover, other types of PH related to CHD exist, including segmental PH and the pulmonary vascular disease (PVD) encountered in patients with a Fontan-type univentricular circulation, in whom even small increases in pulmonary vascular resistance (PVR) have detrimental effects in the absence of a sub-pulmonary ventricle.⁶

Limitations of Standard Echocardiographic Parameters in CHD - Echocardiography is the primary screening tool for PH and can identify patients who require further investigation, including right heart catheterization. PH guidelines describe several "standard" echocardiographic parameters, which increase the probability of PH when present. It is suggested that a raised peak tricuspid regurgitation (TR) velocity should be considered alongside other echocardiographic signs relating to the inferior vena cava, right atrium (RA), ventricles, and pulmonary artery (PA) when screening for PH.^5,7 There are, however, numerous exceptions to these "signs" in patients with CHD that are not within the scope of the guidelines and leave a gap in the recommendations when managing patients with CHD.

Our paper by Dimopoulos et al.⁸ in the Journal of the American College of Cardiology fills this gap in the recommendations. It is an expert opinion paper based on a systematic review and survey of experts. It focuses on both simple (e.g., pulmonary stenosis [PS]) and complex (e.g., unrepaired univentricular hearts or patients with systemic right ventricles) types of CHD. It highlights the importance of an in-depth understanding of the anatomy and pathophysiology of CHD and appropriate use and interpretation of echocardiography to identify CHD patients who have developed PH, ensuring early diagnosis and appropriate management.

To illustrate the above, we provide real-life examples of CHD in which echocardiography has been important in establishing the diagnosis (PH or other), but only when interpreted with caution and integrated with other investigations and expert clinical judgement. (Please click here to view 5 real-life cases)