Effect of Edge-to-Edge Mitral Valve Repair on Chordal Strain: Fluid-Structure Interaction Simulations.

Edge-to-edge repair for mitral valve regurgitation is being increasingly performed in high-surgical risk patients using minimally invasive mitral clipping devices. Known procedural complications include chordal rupture and mitral leaflet perforation. Hence, it is important to quantitatively evaluate the effect of edge-to-edge repair on chordal integrity.

Fluid-Structure Interaction Analysis of Ruptured Mitral Chordae Tendineae.

The chordal structure is a part of mitral valve geometry that has been commonly neglected or simplified in computational modeling due to its complexity. However, these simplifications cannot be used when investigating the roles of individual chordae tendineae in mitral valve closure. For the first time, advancements in imaging, computational techniques, and hardware technology make it possible to create models of the mitral valve without simplifications to its complex geometry, and to quickly run validated computer simulations that more realistically capture its function.

Fluid-structure interaction and structural analyses using a comprehensive mitral valve model with 3D chordal structure.

Over the years, three-dimensional models of the mitral valve have generally been organized around a simplified anatomy. Leaflets have been typically modeled as membranes, tethered to discrete chordae typically modeled as one-dimensional, non-linear cables. Yet, recent, high-resolution medical images have revealed that there is no clear boundary between the chordae and the leaflets.

High-resolution subject-specific mitral valve imaging and modeling: experimental and computational methods.

The diversity of mitral valve (MV) geometries and multitude of surgical options for correction of MV diseases necessitates the use of computational modeling. Numerical simulations of the MV would allow surgeons and engineers to evaluate repairs, devices, procedures, and concepts before performing them and before moving on to more costly testing modalities. Constructing, tuning, and validating these models rely upon extensive in vitro characterization of valve structure, function, and response to change due to diseases.

Fluid-Structure Interaction Analysis of Papillary Muscle Forces Using a Comprehensive Mitral Valve Model with 3D Chordal Structure.

Numerical models of native heart valves are being used to study valve biomechanics to aid design and development of repair procedures and replacement devices. These models have evolved from simple two-dimensional approximations to complex three-dimensional, fully coupled fluid-structure interaction (FSI) systems. Such simulations are useful for predicting the mechanical and hemodynamic loading on implanted valve devices.

Quantitative Evaluation of Annuloplasty on Mitral Valve Chordae Tendineae Forces to Supplement Surgical Planning Model Development.

Purpose: Computational models of the heart's mitral valve (MV) exhibit potential for preoperative surgical planning in ischemic mitral regurgitation (IMR). However challenges exist in defining boundary conditions to accurately model the function and response of the chordae tendineae to both IMR and surgical annuloplasty repair. Towards this goal, a ground-truth data set was generated by quantifying the isolated effects of IMR and mitral annuloplasty on leaflet coaptation, regurgitation, and tethering forces of the anterior strut and posterior intermediary chordae tendineae.

Isolated effect of geometry on mitral valve function for in silico model development.

Computational models for the heart's mitral valve (MV) exhibit several uncertainties that may be reduced by further developing these models using ground-truth data-sets. This study generated a ground-truth data-set by quantifying the effects of isolated mitral annular flattening, symmetric annular dilatation, symmetric papillary muscle (PM) displacement and asymmetric PM displacement on leaflet coaptation, mitral regurgitation (MR) and anterior leaflet strain. MVs were mounted in an in vitro left heart simulator and tested under pulsatile haemodynamics.

Fluid-Structure Interactions of the Mitral Valve and Left Heart: Comprehensive Strategies, Past, Present and Future.

The remodeling that occurs after a posterolateral myocardial infarction can alter mitral valve function by creating conformational abnormalities in the mitral annulus and in the posteromedial papillary muscle, leading to mitral regurgitation (MR). It is generally assumed that this remodeling is caused by a volume load and is mediated by an increase in diastolic wall stress. Thus, mitral regurgitation can be both the cause and effect of an abnormal cardiac stress environment.

Long-term survival after cardiac surgery is predicted by estimated glomerular filtration rate.

Background: Estimated glomerular filtration rate (eGFR) before coronary artery bypass graft (CABG) surgery is a key risk factor of in-hospital mortality. However, in patients with normal renal function before CABG, acute kidney injury develops after the procedure, making postoperative renal function assessment necessary for evaluation. Postoperative eGFR and its association with long-term survival have not been well studied.

Multivariable prediction of renal insufficiency developing after cardiac surgery.

Background: Renal insufficiency after coronary artery bypass graft (CABG) surgery is associated with increased short-term and long-term mortality. We hypothesized that preoperative patient characteristics could be used to predict the patient-specific risk of developing postoperative renal insufficiency.

Methods And Results: Data were prospectively collected on 11,301 patients in northern New England who underwent isolated CABG surgery between 2001 and 2005.

Perioperative increases in serum creatinine are predictive of increased 90-day mortality after coronary artery bypass graft surgery.

Background: Impaired renal function after coronary artery bypass graft (CABG) surgery is a key risk factor for in-hospital mortality. However, perioperative increases in serum creatinine and the association with mortality has not been well-studied. We assessed the hypothesis that perioperative increases in creatinine are associated with increased 90-day mortality.

Non-linear fluid-coupled computational model of the mitral valve.

Background And Aim Of The Study: The dynamics of the mitral valve result from the synergy of left heart geometry, local blood flow and tissue integrity. Herein is presented the first coupled fluid-structure computational model of the mitral valve in which valvular kinematics result from the interaction of local blood flow and a continuum representation of valvular microstructure.

Methods: The diastolic geometry of the mitral valve was assembled from previously published experimental data.

The relationship of normal and abnormal microstructural proliferation to the mitral valve closure sound.

Background: Many diseases that affect the mitral valve are accompanied by the proliferation or degradation of tissue microstructure. The early acoustic detection of these changes may lead to the better management of mitral valve disease. In this study, we examine the nonstationary acoustic effects of perturbing material parameters that characterize mitral valve tissue in terms of its microstructural components.

Potassium supplementation, diet vs pills: a randomized trial in postoperative cardiac surgery patients.

Background: Cardiac surgery patients are commonly treated with diuretics, which can result in hypokalemia requiring potassium supplementation.

Objective: Our objective was to determine whether cardiac surgery patients receiving therapy with potassium-wasting diuretics can safely and beneficially maintain serum potassium levels by eating potassium-rich foods.

Design: A prospectively randomized trial of diet vs medication supplementation of potassium was undertaken.

A coupled fluid-structure finite element model of the aortic valve and root.

Background And Aim Of The Study: The study aim was to develop a three-dimensional coupled fluid-structure finite element model of the aortic valve and root. This model extends previous purely structural finite element models, and represents a significant step toward realistic simulation of the complex interactions among tissue material properties and valvular function.

Methods: The aortic root and valve geometry were extracted from magnetic resonance images and imported into the LS-Dyna explicit finite element package.

Biaxial mechanical properties of porcine ascending aortic wall tissue.

Background And Aim Of The Study: Biaxial mechanical properties have been reported for porcine aortic valve leaflets, but not for the aortic root wall. These data are important for understanding the relationship between tissue material properties and function, providing a baseline for diseased tissue, and for providing a basis for numerical models of aortic mechanics. The study aim was to determine the biaxial material properties of porcine aortic root wall tissue.

Ambulatory intraaortic balloon pump use as bridge to heart transplant.

Background: This study evaluates a modification of an ambulatory intraaortic balloon pump (IABP) technique used in patients with heart failure of ischemic origin for bridge to transplant.

Methods: In this retrospective review we evaluated the ability to place the ambulatory IABP, any complications, time on device, and success in bridging to transplant on the ambulatory IABP device. In addition, the cost as compared to current ventricular assist devices was determined.