Understimation of Murine Cardiac Hemodynamics using Invasive Catheters

Abstract

This study quantifies an error in the estimation of hemodynamic indices of global cardiac function from use of commercial catheters in mice. Male C57BL/6 mice (n=5, age=8–12wks, weight=25.5±3.3 g) were imaged on a 7T MRI scanner under 1.5% ISO in 100% O2; computational myocardial and catheter finite element models were constructed. A composite model of the catheter‐myocardium was imported in XFdtd for electric (E) field simulations. Comparison of end‐diastolic (ED) and end‐systolic (ES) volume estimates from such simulations show mean underestimation errors between −8.3±52.9 and −68.9±10.4%. Propagation of such errors in stroke volume, cardiac output, and ejection fraction estimation yields errors of 85.4±29.1, 182.3±117.4, 132.9±171.1%, respectively, given a catheter E‐field detection sensitivity of 5%. Modification of the commercial catheter design is shown to minimize underestimation errors of such indices, based on simulations. Elicited response improvements (peak amplitude and spatial extent) are quantified to be 405% and 52% (3.8 vs. 2.5 mm at 1% E‐field fall‐off) in ED, and 934 and 80% in ES, for the new catheter, compared to the commercially available design. Reductions in absolute hemodynamic error estimates were also computed (4.8–60.8%) for the new catheter in one mouse. Implementation of the newly proposed catheter design can lead to improved accuracy of indices of cardiac function.