Characterization of patient-specific biventricular mechanics in heart failure with preserved ejection fraction: Hyperelastic warping.

Heart failure with preserved ejection fraction (HFPEF) is considered as a major public health problem. Traditionally, HFPEF is diagnosed based on a "normal" EF, but the studies have explored the potential role of left ventricular mechanics. Furthermore, right ventricular mechanics and bi-ventricular interaction in HFPEF is currently not well understood. In this study, we aim to develop a framework using a hyperelastic warping approach to quantify bi-ventricular and septum strains from cardiac magnetic resonance (CMR) images. Whole heart models were reconstructed in HFPEF, HF with reduced EF (HFREF) and normal control patients, and a Laplace-Dirichlet Rule-Based (LDRB) algorithm was employed to assign circumferential orientation. The LV circumferential strain was 10.56% in normal control, and decreased to 5.90% in HFPEF and 1.66% in HFREF. Interestingly, the RV circumferential strain was 7.29% in normal control, but increased to 8.93% in HFPEF, and decreased to 2.16% in HFREF. The septum circumferential strain was comparable between HFPEF and normal control. Heart failure with preserved ejection fraction demonstrated augmented right ventricular strain and comparable septum strain to maintain its "normal" ejection fraction. This might unveil a new mechanism of bi-ventricular interaction and compensation in heart failure with preserved ejection fraction.