Gyroscan 1.5t nt

We used a previously developed canine biventricular geometry [11] (link), constructed from cardiac magnetic resonance image (MRI) data obtained by a Philips Gyroscan 1.5T (NT, Philips Medical Systems, Best, Netherlands) at end-diastolic phase from a 20.6 kg mongrel dog [24] (link). A finite element discretization was generated using CGAL (www.cgal.org) and smoothed using meshtool [25] (link). The discretized geometry consisted of 111,234 points defining 557,316 tetrahedral elements with an average edge length of 1.3 mm (see Fig. 1). The fibers were constructed with a rule-based algorithm [26] (link) with fiber angles of 60° and -60°, and sheet angles of -65° and 25° on the endocardial and epicardial surfaces respectively. Two planes covering the cavities were used to model the stiffness of the base of the heart and to provide closed cavities for the biventricular geometry, as shown in Fig. 1.

In a previous study, see [45 (link)], mongrel dog data were acquired to investigate the influence of different pacing protocols on cardiac mechanics, pump function and efficiency. The animals were handled according to the Dutch Law on Animal Experimentation (WOD) and the European Directive for the Protection of Vertebrate Animals Used for Experimental and Other Scientific Purposes (86/609/EU). The protocol was approved by the Maastricht University Experimental Animal Committee. Anatomical Magnetic Resonance Images (MRI) were acquired on a Philips Gyroscan 1.5 T (NT, Philips Medical Systems, Best, the Netherlands) using a standard synergy receiver coil for thorax examinations. Images of seven short-axis cross-sections of slice thickness 8mm with 0mm inter-slice distance were obtained to capture the whole heart. LV pressure and volume were determined using the conductance catheter technique (CD-Leycom, The Netherlands), see [46 (link)], and the signals were digitized at 1 kHz.