Applications of computational modeling in cardiac surgery

Abstract

Although computational modeling is common in many areas of science and engineering, only recently have advances in experimental techniques and medical imaging allowed this tool to be applied in cardiac surgery. Despite its infancy in cardiac surgery, computational modeling has been useful in calculating the effects of clinical devices and surgical procedures. In this review, we present several examples that demonstrate the capabilities of computational cardiac modeling in cardiac surgery. Specifically, we demonstrate its ability to simulate surgery, predict myofiber stress and pump function, and quantify changes to regional myocardial material properties. In addition, issues that would need to be resolved in order for computational modeling to play a greater role in cardiac surgery are discussed.

Figure 1

(a): Computational cardiac mechanics as an intersection of three domains: continuum mechanics, materials science and numerical method. (b): A FE mesh of a LV. The elements (demarcated by the black lines) are inter-connected through nodes (shown in pink).

Figure 2

Simulation of the Cardiokinetix Parachute Device. (a) Upper: CT image of the Parachute device implanted in a patient. Lower: the Parachute device. (b) Simulating the deployment of the Parachute device in the FE model. (c) Comparison of the LV myofiber stress distribution at ED before and after treatment.

Figure 3

Simulation of the Acorn CorCap CSD. (a) Upper: biventricular FE model showing the LV in red and right ventricle in grey. Lower: CSD model before attachment to the biventricular model as outlined by the red and gray lines. Criss-cross white lines indicate the CSD fiber orientations. (b) Effects of CSD on ED and ES pressure-volume relationships. (c) Effects of CSD on Starling’s relationships. “Tight ACORN” refers to the case when a 5% pre-stretch was applied to the CSD and “LV-Only” refers to the case when the CSD encircles only the LV.

Figure 4

Simulation of the Dor procedure. (a) Left: magnetic resonance image showing the long-axis view of the sheep LV after MI. MI and SI denote the dyskinetic and septal infarct, respectively. Tagged lines used to compute the myocardial strain can also be seen in the image. Top right: FE model of the LV. Bottom right: view of a cross section slice of the FE model. Blue, red, brown and green regions denote the infarct, the BZ 1, BZ 2 and the remote region, respectively. (b) Effects of Dor procedure on the regional myocardial contractility as reflected by the systolic material parameter. (c) Effect of Dor procedure on the longitudinal and transmural distributions of end-systolic myofiberstress pre-Dor (left) and 6weeks post-Dor (right) in a typical sheep. Fringe level units in hPa.

Figure 5

Simulation of mitral valve annuloplasty. (a) FE model of the LV with the mitral valve apparatus i.e. mitral valve leaflets, chordae tendinae and the papillary muscle. (b) Annuloplasty rings with different shapes (from Edward Lifesciences, Inc, Irvine, CA). Top: saddle shape ring (Physio II). Bottom: asymmetric ring (IIMR ETlogix). (c): Annuloplasty ring virtually sutured to the mitral annulus (MA). Tension is imposed in the virtual suture (VS, shown here without tension) so that MA is pulled towards annuloplasty ring (AL = anterior leaflet, PL = posterior leaflet). (d): Improvement of the mitral leaflet coaptation after mitral annuloplasty.