Pulmonary Artery Characteristics in Congenital Heart Diseases Evaluated by Optical Coherence Tomography

INTRODUCTION: Assessment of pulmonary vascular disease in children with congenital heart disease (CHD) relies primarily on invasive hemodynamic measurements, including pulmonary vascular resistance index (PVRi). However, these parameters may not fully reflect the underlying structural changes associated with pulmonary vascular remodeling. This study aimed to evaluate the utility of optical coherence tomography (OCT) for in vivo assessment of pulmonary arterial remodeling and examined the relationship between OCT-derived parameters and pulmonary hypertension (PH) severity. METHODS: Eleven patients with CHD (mean age 10 years, range 2-23 years; 7 females) undergoing clinically indicated cardiac catheterization were prospectively enrolled. OCT imaging was successfully performed in 63 pulmonary artery (PA) segments. Hemodynamic parameters, including mean pulmonary arterial pressure (mPAP), mPAP/systemic arterial pressure ratio (MAP), and PVRi, were compared between the PH and control groups. Correlations between OCT-derived measurements and hemodynamic indices were analyzed. RESULTS: Patients with PH had significantly higher mPAP (39±16 vs. controls, p=0.002), mPAP/MAP ratio (0.58±0.24, p=0.017), and PVRi (median 6.05 [IQR 2.27-6.60] WU·m², p=0.008). OCT demonstrated significantly greater %PA wall thickness in the PH group compared with controls (19.4±1.1% vs. 13.5±0.9%, p<0.0001). Percentage wall thickness showed significant positive correlations with mPAP (r=0.58), mPAP/MAP ratio (r=0.62), transpulmonary gradient (r=0.60), PVRi (r=0.55), and Rp/Rs ratio (r=0.45) (all p<0.001). Notably, marked wall thickening (21.8%) was identified in a patient with only mildly elevated PVRi (2.2 WU·m²). CONCLUSIONS: OCT provides structural insights into pulmonary vascular remodeling and complements to conventional hemodynamic assessment in PH related to CHD in children. Pulmonary artery wall thickness percentage correlates closely with PH severity and may serve as a sensitive marker of pulmonary vascular disease in children with CHD.