13th International Conference on Fracture June 16–21, 2013, Beijing, China -2- Fig. 1. Schematic drawing of the MV showing the valve leaflets, the papillary muscles and the MCT, (a), and schematic drawing of a MV as a continuous piece of tissue, (b). 1.2. Mitral valve calcification Mitral regurgitation (MR) is the reflux of blood from the left ventricle into the left atrium during cardiac systole [4]. Carpentier et al. introduced a pathophysiologic classification of MR [2] based on the mitral leaflet motion. MR with normal motion is type I, with increased motion is type II and with restricted motion is type III. Heart valves are frequent locations of extensive calcium deposits, in particular because of rheumatic disease [19, 18, 6, 25]. 1.3. Scope of the research In this experimental study, the biomechanical properties of normal and calcified human MCT were determined. The objectives of the study are threefold: (i) to characterise (by means of quasi-static tensile tests) the mechanical behaviour of normal and calcified MCT; (ii) to quantitatively determine (through atomic absorption spectroscopy, AAS) the amount of calcium present in MCT, correlating this content with their mechanical response; (iii) to describe (through scanning electron microscopy, SEM) the relevant features associated to the fracture process and to the calcium deposits in the MCT. In the past, several studies [12, 21, 8, 16, 14, 15, 28, 10] were carried out in order to characterise the mechanical response of MCT. Nevertheless, to the knowledge of the authors, no experimental data on calcified human MCT are currently available, the present work being, therefore, the first attempt to obtain this information. 1.4. Material and methods After receiving the approval of the Ethics Committee of the Marqués de Valdecilla University Hospital (Santander, Spain), the surgeons participating in the research provided a set of 13 human MVs. They classified the available MVs into three different groups: (i) 6 were obtained from patients (4 men and 2 women, aged between 36 and 63) who required heart transplant and whose MVs were not affected by any disease. The functional marginal MCT excised from these MVs constitute the control group of this study; (ii) 4 moderately calcified MVs and, (iii) 3 strongly calcified MVs, were obtained from patients who required valve replacement (1 man and 3 women, aged between 48 and 74 for the moderately calcified; 2 men and 1 women, aged between 54 and 79 for the strongly calcified Mvs). The overall appearance of the three kinds of mitral valves is shown in Fig. 2. The MVs provided by the surgeons were taken from the operating room to the mechanical laboratory in a portable refrigerator. The protocol proposed by Prot [22] was followed to preserve the integrity of the biological material.
RkJQdWJsaXNoZXIy MjM0NDE=