Right Ventricular Myocardial Stiffness and Relaxation Components by Kinematic Model-Based Transtricuspid Flow Analysis in Children and Adolescents with Pulmonary Arterial Hypertension

We hypothesized that the kinematic model-based parameters obtained from the transtricuspid E-wave would be useful for evaluating RV diastolic property in pediatric pulmonary arterial hypertension (PAH) patients. The model was parametrized by stiffness/elastic recoil k, relaxation/damping c, and load x. These parameters were determined as the solution of m⋅d2x/dt2 + c⋅dx/dt + kx = 0, which is based on the theory that the E-wave contour is determined by the interplay of stiffness/restoring force, damping/relaxation force, and load. The PAH group had a significantly higher k and c versus the control group (182.5 ± 72.4 g/s2 vs. 135.7 ± 49.5 g/s2, p = 0.0232 and 21.9 ± 6.5 g/s vs. 10.6 ± 5.2 g/s, p <0.0001, respectively). These results show that RV has a higher stiffness/elastic recoil and inferior cross-bridge relaxation in the PAH group. Present findings indicate the feasibility and utility of kinematic model parameters for assessing RV diastolic function.

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