Infrared skin temperature measurements for monitoring health in pigs: a review.

Infrared temperature measurement equipment (IRTME) is gaining popularity as a diagnostic tool for evaluating human and animal health. It has the prospect of reducing subject stress and disease spread by being implemented as an automatic surveillance system and by a quick assessment of skin temperatures without need for restraint or contact. This review evaluates studies and applications where IRTME has been used on pigs. These include investigations of relationships between skin, ambient and body temperatures and applications for detecting fever, inflammation, lesions, ovulation, and stress as well as for meat quality assessment. The best skin locations for high correlation between skin temperature and rectal temperature are most likely thermal windows such as ear base, eye region and udder. However, this may change with age, stressors, and biological state changes, for example, farrowing. The studies performed on pigs using IRTME have presented somewhat discrepant results, which could be caused by inadequate equipment, varying knowledge about reliable equipment operation, and site-specific factors not included in the assessment. Future focus areas in the field of IRTME are suggested for further development of new application areas and increased diagnostic value in the porcine and animal setting in general.

Mitral valve function and chordal force distribution using a flexible annulus model: an in vitro study.

Since variations in annular motion/shape and papillary muscle displacement have been observed in studies of dilated cardiomyopathy and ischemic mitral regurgitation, the objective of this study was to investigate the effects of annular motion/flexibility and papillary muscle displacement on chordal force and mitral valve function. Six human mitral valves were studied in a left heart simulator using a flexible annular model. Mitral flow, trans-mitral pressure and chordae tendineae tension were monitored online in normal and pathophysiologic papillary muscle positions. The flexible annulus model showed a significant increase in mitral regurgitation volume (p < 0.05) when compared to static annuli models. Furthermore, there was a significant increase of force on the basal chords compared to the force present with the static annuli models. Utilizing the flexible annulus model, papillary muscle displacement significantly increased the force on the anterior strut, posterior intermediate and commissural chords. (1) Papillary muscle displacement increases the tension on the intermediate chords inducing tenting of the leaflets and subsequent regurgitation. (2) The tension on the intermediate and marginal chords is relatively insensitive to annular motion, whereas tension on the basal chords is directly affected by annular motion.

Effects of papillary muscle position on chordal force distribution: an in-vitro study.

BACKGROUND AND AIM OF THE STUDY: Mitral insufficiency, a common and morbid pathology, has been related to topological changes in the left ventricle. These changes may affect mitral leaflet coaptation by displacing the tips of the papillary muscles (PMs), subsequently changing the tension distribution on the chordae tendineae. Therefore, further understanding of the effects of PM displacement on chordal force distribution is required. METHODS: Six human and five porcine mitral valves were studied in a physiological left heart simulator. Cardiac output and transmitral pressure were recorded online and maintained within physiological ranges. Force transducers were placed on six chordae tendineae to measure chordal force distribution. Tension on individual chordae tendineae was recorded online during the cardiac cycle. The experiment was conducted for eight different PM positions, which were constructed from 5-mm vectorial displacements from the normal PM position. RESULTS: The anterior strut chord showed significant (p <0.05) variations in peak systolic tension (PST) for those positions associated with apical motion of the PMs. The posterior intermediate chord also showed significant variations in PST for positions associated with apical displacement of the PMs, whereas posterior displacement of the PMs resulted in a reduction in tension. In contrast, both the anterior marginal and posterior marginal chords showed a relatively uniform PST for the eight different PM positions. The posterior basal and commissural chords were the most sensitive to tension variations due to PM displacement. These chords showed relatively large and significant (p <0.05) variations in PST for most of the different PM displacements. CONCLUSION: The effects of PM relocation on chordal tension depended on chordal type. Chords which insert closer to the annulus were more sensitive to PM displacement, whereas those further from the annulus, the marginal chords, were the least sensitive to PM displacement.

Effects of a saddle shaped annulus on mitral valve function and chordal force distribution: an in vitro study.

Studies have concluded that the shape of the human mitral valve annulus is a three-dimensional saddle. The objective of this study was to investigate the effects of a saddle shaped annulus on chordal force distribution and mitral valve function. Eleven human mitral valves were studied in a physiological left heart simulator with a variable shaped annulus (flat versus saddle). Cardiac output and transmitral pressure were analyzed to determine mitral regurgitation volume. In six experiments, force transducers were placed on six chordae tendineae to measure chordal force distribution. Valves were tested in normal and pathophysiologic papillary muscle positions. When comparing the flat and saddle shaped configurations, there was no significant difference in mitral regurgitation volume 11.2% +/- 24.7% (p = 0.17). In the saddle shaped configuration, the tension on the anterior strut chord was reduced 18.5% +/- 16.1% (p < 0.02), the tension on the posterior intermediate chord increased 22.3% +/- 17.1% (p < 0.03), and the tension of the commissural chord increased 59.0% +/- 32.2% (p < 0.01). Annular shape also altered the tensions on the remaining chords. Annular shape alone does not significantly affect mitral regurgitation caused by papillary muscle displacement. A saddle shaped annulus redistributes the forces on the chords by altering coaptation geometry, leading to an optimally balanced anatomic/physiologic configuration.