Three-dimensional myocardial strain correlates with murine left ventricular remodelling severity post-infarction

Abstract

<jats:p>Heart failure continues to be a common and deadly sequela of myocardial infarction (MI). Despite strong evidence suggesting the importance of myocardial mechanics in cardiac remodelling, many MI studies still rely on two-dimensional analyses to estimate global left ventricular (LV) function. Here, we integrated four-dimensional ultrasound with three-dimensional strain mapping to longitudinally characterize LV mechanics within and around infarcts in order to study the post-MI remodelling process. To induce infarcts with varying severities, we separated 15 mice into three equal-sized groups: (i) sham, (ii) 30 min ischaemia–reperfusion, and (iii) permanent ligation of the left coronary artery. Four-dimensional ultrasound from a high-frequency small animal system was used to monitor changes in LV geometry, function and strain over 28 days. We reconstructed three-dimensional myocardial strain maps and showed that strain profiles at the infarct border followed a sigmoidal behaviour. We also identified that mice with mild remodelling had significantly higher strains in the infarcted myocardium than those with severe injury. Finally, we developed a new approach to non-invasively estimate infarct size from strain maps, which correlated well with histological results. Taken together, the presented work provides a thorough approach to quantify regional strain, an important component when assessing post-MI remodelling.</jats:p>

Rapid custom prototyping of soft poroelastic biosensor for simultaneous epicardial recording and imaging

“…1a ). 24 , 25 Details of the 4D heart segmentation are included in the Methods section. This 3D geometry was taken into consideration to precisely scale, adjust, and tailor the overall layout of the device to meet the requirement of a specific geometric accuracy.…”

Cardiac mechanostructure: Using mechanics and anisotropy as inspiration for developing epicardial therapies in treating myocardial infarction

“…Recently, techniques to quantify local mechanics, such as strain profiles, degree of rotation and angular velocity within the ventricular wall, have proven to be sensitive indices in detecting ventricular performance [ 16 ]. These metrics can be measured by tracking myocardial motion non-invasively through speckle tracking echocardiography [ 17 , 18 ], tagged-MRI [ 19 ], 4D ultrasound with 3D strain mapping [ 20 ] as well as tracking transmural myocardial fiber organization through diffusion tensor MRI [ [21] , [22] , [23] ] and 3D ultrasound backscatter tensor imaging [ 24 ]. These techniques are especially important when considering cardiovascular diseases such as heart failure with preserved ejection fraction (HFpEF), recently declared by the National Heart, Lung and Blood Institute as the “greatest unmet need in cardiovascular medicine” [ 25 ].…”

Rapid Custom Prototyping of Soft Poroelastic Biosensor for Simultaneous Epicardial Recording and Imaging

“…A surgery to permanently ligate the left coronary artery was performed following the same procedures as reported in previous studies. 19 Representative measurement results of the epicardial ECG signals are shown in Figure 5b. Following approximately 30 seconds of the ligation, acute ST-segment elevation events (red circles in the middle panel) occurred near the ligation point where the sensor channels 2 and 3 were located.…”

“…The initial design process began by capturing the overall size, geometry, and structure of the infarcted area of a specific heart through four-dimensional (4D) segmentation (i.e., 3D geometric volume over a cardiac cycle) of the myocardium constructed by lofting sequential short axis (SAX) endocardial and epicardial boundaries from ultrasound images (Figure 1a). 19,20 Details of the 4D heart segmentation and lofting are shown in the Methods section. This information was taken into consideration to carefully scale and adjust the overall layout of the device in order to meet the requirement of a specific geometric accuracy such that the distance between the pairs of recording electrodes can fit well to the position and orientation of the infarcted area.…”