BACKGROUND: Congenital diaphragmatic hernia (CDH) is a structural birth defect associated with pulmonary hypoplasia and pulmonary arterial hypertension (PAH). We hypothesize that echocardiography provides a method to assess real-time right ventricle (RV) function, remodeling, and pulmonary artery (PA) flow.
MATERIALS AND METHODS: Slit3 wild-type (WT) (n = 6) and knockout (KO) (n = 5) mice were analyzed at 2-3 months of age. Mice were anesthetized using isoflurane. Echocardiography was performed to analyze left and right ventricular wall thickness, internal diameter (ID), and function. Color Doppler was used to analyze flow in the PA and across the tricuspid valve.
RESULTS: There was significant RV dilation in the KO mice versus WT, with an average RVID of 1.99 mm versus 1.26 mm, respectively (P = 0.007). Flow in the PA of KO mice was altered compared to WT, with elevated PA velocity time indices, 30.68 mm versus 22.13 mm (P = 0.012), elevated PA peak velocities, 952.61 mm/s versus 628.73 mm/s (P = 0.003), and decreased pulmonary acceleration times, 8.94 ms versus 16.18 ms (P = 0.002), respectively. Pulmonary vascular resistance, calculated by measuring tricuspid regurgitation peak velocity and right ventricular outflow tract velocity time index, was increased in KO versus WT mice, 17.61 mm2/s versus 8.91 mm2/s (P = 0.003), respectively.
CONCLUSIONS: Slit3 KO mice with CDH show evidence of PAH and resultant RV dilation. Using direct cardiac puncture, elevated RV systolic pressures have been demonstrated in KO mice as evidence of PAH. Echocardiography allows direct analysis of the PA and real-time RV function without sacrifice of the mouse. This mode of evaluation allows longitudinal study in mice with PAH and CDH
