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Updated: May 28, 2026
In Vivo Quantitative Assessment of Myocardial Structure, Function, Perfusion and Viability Using Cardiac Micro-computed Tomography
Published on: February 16, 2016
A novel method for quantifying in-vivo regional left ventricular myocardial contractility in the border zone of a
Lik Chuan Lee1, Jonathan F Wenk, Doron Klepach
1Departments of Surgery and Bioengineering, University of California, San Francisco, CA 94143, USA. likchuan@berkeley.edu
Insights
Mathematical models of the left ventricle (LV) often assume discontinuous contractility. This study introduces a new model with a smooth, linear transition in the border zone (BZ) for improved accuracy in simulating myocardial infarction.
Area of Science:
- Cardiovascular biomechanics
- Computational modeling
- Medical imaging analysis
Background:
- Existing left ventricular (LV) mathematical models typically assign homogeneous contractility to distinct regions: remote, border zone (BZ), and infarct, resulting in discontinuous contractile function.
- This simplification may not accurately represent the physiological transition of contractility in infarcted hearts.
Purpose of the Study:
- To test the hypothesis that the BZ exhibits a smooth, linear transition in contractility between the remote region and the infarct.
- To develop and validate a mathematical model of a sheep LV with an anteroapical infarct incorporating linearly-varying BZ contractility.
Main Methods:
- Developed a mathematical model of a sheep left ventricle (LV) with an anteroapical infarct and linearly-varying border zone (BZ) contractility.
- Employed an established optimization method to extract active material parameter T(max) and BZ width d(n).
- Validated the model against in-vivo systolic strain fields derived from tagged magnetic resonance images (MRI).
Main Results:
- The proposed model, featuring a linearly-varying BZ contractility, significantly reduced mean square errors compared to a model with homogeneous regional contractility.
- The model successfully predicted in-vivo systolic strain fields measured from tagged MRI.
- Peak fiber stress differed by approximately 15% between the two models, highlighting the impact of the contractility transition.
Conclusions:
- The hypothesis that the border zone (BZ) represents a smooth, linear transition in contractility is confirmed.
- Mathematical models of the left ventricle (LV), especially those for analyzing myocardial infarction treatments, should incorporate this linear transition within the BZ for enhanced accuracy.
- Accurate modeling of BZ contractility is crucial for predicting cardiac mechanics and evaluating therapeutic interventions.
Abstract:
Homogeneous contractility is usually assigned to the remote region, border zone (BZ), and the infarct in existing infarcted left ventricle (LV) mathematical models. Within the LV, the contractile function is therefore discontinuous. Here, we hypothesize that the BZ may in fact define a smooth linear transition in contractility between the remote region and the infarct. To test this hypothesis, we developed a mathematical model of a sheep LV having an anteroapical infarct with linearly-varying BZ contractility. Using an existing optimization method (Sun et al., 2009, "A Computationally Efficient Formal Optimization of Regional Myocardial Contractility in a Sheep With Left Ventricular Aneurysm," J. Biomech. Eng., 131(11), pp. 111001), we use that model to extract active material parameter T(max) and BZ width d(n) that "best" predict in-vivo systolic strain fields measured from tagged magnetic resonance images (MRI). We confirm our hypothesis by showing that our model, compared to one that has homogeneous contractility assigned in each region, reduces the mean square errors between the predicted and the measured strain fields. Because the peak fiber stress differs significantly (~15%) between these two models, our result suggests that future mathematical LV models, particularly those used to analyze myocardial infarction treatment, should account for a smooth linear transition in contractility within the BZ.
