Right Ventricular Fiber Structure as a Compensatory Mechanism in Pressure Overload: A Computational Study

Area of Science:

• Cardiovascular Physiology
• Computational Biology
• Biomedical Engineering

Background:

• Right ventricular failure (RVF) is a critical condition with limited understanding of its biomechanical factors.
• Pressure overload is a primary cause of RVF, yet compensatory tissue remodeling mechanisms remain unclear.
• Investigating the impact of structural changes on RV function is challenging experimentally.

Purpose of the Study:

• To computationally investigate the role of myocardial fiber orientation as a compensatory mechanism in right ventricular pressure overload (RVPO).
• To quantify the effect of altered fiber orientation on right ventricular (RV) pump function under pressure overload conditions.
• To explore the interplay between fiber orientation, wall thickness, and contractility in RV adaptation.

Main Methods:

• Developed numerical biventricular models based on rabbit RV pressure overload data.
• Utilized CINE MRI and diffusion tensor MRI (DT-MRI) for model parameterization.
• Conducted simulations under varying RV wall thickness, tissue stiffness, and fiber orientation.

Main Results:

• Longitudinally aligned myocardial fibers significantly increased right ventricular ejection fraction (RVEF), especially under pressure overload.
• Models with longitudinal fiber orientation required less contractility to maintain RVEF against elevated pressures.
• Findings suggest myocardial fiber realignment is a key systolic compensatory mechanism alongside diastolic adaptations.

Conclusions:

• Myocardial fiber orientation is a quantifiable and significant compensatory mechanism in right ventricular pressure overload.
• Altered fiber orientation can enhance RV pump function and reduce the need for increased contractility.
• This study highlights the importance of considering fiber mechanics in understanding and potentially treating RVF.