Sequential Changes in Right Ventricular Strain During the Development of Pulmonary Hypertension Assessed With Magnetic Resonance Feature Tracking: An Animal Study.

objectiveTo evaluate the sequential changes in right ventricular (RV) strain and histological vascular remodeling and their correlations during pulmonary hypertension (PH) development in a rat model by using cardiac magnetic resonance (CMR)-feature tracking (FT). MATERIALS AND

methodsSeparate cohorts of six-week-old male Wistar rats (10 per group) were allocated to a baseline group, PH induction groups assessed at 1, 2, 3, or 4 weeks after monocrotaline injection, and vehicle-injected control groups assessed at 2 and 4 weeks. Each rat underwent a single magnetic resonance imaging (MRI) examination and was subsequently euthanized for histological analysis. Cine images were acquired using a 9.4T MRI scanner, and strain was analyzed using the FT technique. Histological analysis was used to quantify pulmonary arterial wall thickness percentage (PA %WT) and RV collagen density. Overall group differences were analyzed using the Kruskal-Wallis test, which was followed by the Mann-Whitney U test with Bonferroni correction for pairwise comparisons with the baseline group. Correlations between the variables were assessed using Spearman's correlation coefficients.

resultsAll CMR-derived RV parameters showed significant differences across the baseline and PH induction groups (all

conclusionIn this preclinical model of PH, staged CMR and histological assessments demonstrated sequential RV remodeling in parallel with PA remodeling, with RVFWLS impairment preceding overt RV dysfunction and enlargement.