Biology subjects

Morgan, A. E.

Publications and source records attributed to Morgan, A. E..

2 recordsLinked to original sources

bioRxiv2019

A novel MRI-based finite element modeling method for calculation of myocardial ischemia effect in patients with functional mitral regurgitation.

BackgroundFunctional Mitral Regurgitation (FMR) affects nearly 3 million patients in the United States. Conventional indices are limited for predicting FMR response to coronary revascularization (REVASC). Uncertainty as to which patients will respond to REVASC alone impedes rational decision-making regarding FMR management. Determination of myocardial material parameters associated with ischemic myocardium will address knowledge gaps regarding the impact of ischemia on regional cardiac muscle.\n\nMethodWe proposed a novel MRI-based finite element (FE) modeling method to determine the effect of ischemia on myocardial contractility. The method was applied to two patients with multi-vessel coronary disease and FMR and one healthy volunteer. Cardiac MRI (CMR) included cine-MRI, gadolinium-enhanced stress perfusion, late gadolinium enhancement (LGE), and non-invasive tagged MRI (CSPAMM). The left ventricular (LV) FE model was divided into 17 sectors. Sector-specific circumferential and longitudinal end-systolic strain and LV volume from CSPAMM were used in a formal optimization to determine the sector based myocardial contractility, Tmax.\n\nResultsThe FE optimization successfully converged with good agreement between calculated and experimental end-systolic strain and LV volumes. Specifically, the optimized TmaxH for Patient 1, Patient 2, and the volunteer was 336.8 kPa, 401.4 kPa, and 259.4 kPa and for Patient 1 and Patient 2 was 0.44 and 0.\n\nConclusionWe developed a novel computational method able to predict the effect of myocardial ischemia in patients with FMR. This method can be used to predict the effect of ischemia on the regional myocardium and promises to facilitate better understanding of FMR response to REVASC.

bioengineering↗

bioRxiv2019

Mechanical effects of MitraClip on leaflet stress and myocardial strain in functional mitral regurgitation: A finite element modeling study.

PurposeMitraClip is the sole percutaneous device approved for functional mitral regurgitation (MR; FMR) but MR recurs in over one third of patients. As device-induced mechanical effects are a potential cause for MR recurrence, we tested the hypothesis that MitraClip increases leaflet stress and procedure-related strain in sub-valvular left ventricular (LV) myocardium in FMR associated with coronary disease (FMR-CAD).\n\nMethodsSimulations were performed using finite element models of the LV + mitral valve based on MRI of 5 sheep with FMR-CAD. Models were modified to have a 20% increase in LV volume ({uparrow}LV_VOLUME) and MitraClip was simulated with contracting beam elements (virtual sutures) placed between nodes in the center edge of the anterior (AL) and posterior (PL) mitral leaflets. Effects of MitraClip on leaflet stress in the peri-MitraClip region of AL and PL, septo-lateral annular diameter (SLAD), and procedure-related radial strain (Err) in the sub-valvular myocardium were calculated.\n\nResultsMitraClip increased peri-MitraClip leaflet stress at end-diastole (ED) by 22.3{+/-}7.1 kPa (p<0.0001) in AL and 14.8{+/-}1.2 kPa (p<0.0001) in PL. MitraClip decreased SLAD by 6.1{+/-}2.2 mm (p<0.0001) and increased Err in the sub-valvular lateral LV myocardium at ED by 0.09{+/-}0.04 (p<0.0001)). Furthermore, MitraClip in {uparrow}LV_VOLUME was associated with persistent effects at ED but also at end-systole where peri-MitraClip leaflet stress was increased in AL by 31.9{+/-}14.4 kPa (p=0.0268) and in PL by 22.5{+/-}23.7 kPa (p=0.0101).\n\nConclusionsMitraClip for FMR-CAD increases mitral leaflet stress and radial strain in LV sub-valvular myocardium. Mechanical effects of MitraClip are augmented by LV enlargement.

bioengineering↗