Introduction

Congenital heart disease (CHD) affects approximately 8 to 10 out of every 1000 live births.1 2 Severe heart defects requiring early-life treatment and surgical interventions are referred to as Critical Congenital Heart Diseases (CCHD), accounting for 25–40% of CHDs.3 Many CCHDs depend on the patency of the arterial duct for survival. Without early diagnosis and management, they deteriorate and may even die shortly after duct closure. Timely detection of CCHD during the neonatal period is crucial for reducing morbidity and mortality, improving the patient’s quality of life.1 3

Despite increasing prenatal diagnosis, a significant proportion of neonates with CCHD remain undiagnosed before hospital discharge.4 5 Pulse oximetry test (POT) screening has been recommended as an initial CCHD screening tool since 2009, demonstrating good results in reducing CCHD-related mortality. However, left-sided obstructive lesions, particularly aortic coarctation (CoA), are often missed by pulse oximetry screening due to their association with low systemic perfusion without significant hypoxaemia.6 7

Late diagnosis of CoA and similar defects can be detrimental, with a mortality rate of 18% in neonates who are diagnosed late. Altogether, over 50% CCHD-related deaths occur before corrective surgery can be performed.3

Simultaneous plethysmographic analysis of upper and lower limbs has the potential to detect left-sided obstructive anomalies but is not yet incorporated in routine clinical practice.7

Plethysmography has been used in adults since the 1990s to evaluate peripheral arterial disease or vessel stiffness.8–10 These commercially available devices are designed for studies …