Papillary muscle force distribution after total tricuspid reconstruction using porcine extracellular matrix: in-vitro valve characterization.

BACKGROUND AND AIM OF THE STUDY

The use of extracellular matrix (ECM) from the porcine small intestinal submucosa has shown promising results in reconstructive heart surgery. The study aim was to compare native and ECM tricuspid valves with regards to tricuspid leaflet coaptation geometry and force development in the three papillary muscles, under normal ventricular pressures.

METHODS

Six native porcine tricuspid valves and five ECM valves were examined in a static pressure right-heart simulator. Water was used in the ventricular chamber to induce adequate pressure changes (from 5 to 40 mmHg). Dedicated force transducers were used to measure force development in the three papillary muscles in parallel with ventricular pressure measurements. Relative leaflet area was defined as the percentage that one leaflet area comprised of the whole orifice area. The estimated peak leaflet pressure force was defined as leaflet area x peak ventricular pressure, and peak leaflet tethering force was calculated as the average of two adjacent papillary muscles forces. Valve competence and leaflet areas were documented using digital photography.

RESULTS

The relative leaflet area of the anterior leaflet was significantly smaller (0.4 versus 0.5, p < 0.01) and that of the posterior leaflet was significantly larger (0.3 versus 0.2; p < 0.001) in ECM tube grafts compared to native valves. No difference was found between septal leaflet relative areas (p > 0.1). Accordingly, estimated peak leaflet pressure forces were greater in anterior leaflets and smaller in the posterior leaflets of native valves compared to ECM valves (p < 0.01). However, peak papillary muscle forces and peak leaflet tethering forces did not differ significantly between the valves.

CONCLUSION

A competent and functional tricuspid valve can be constructed in vitro from ECM. In spite of different leaflet area distributions, the force distribution and tethering forces were not significantly different between the two valve types, indicating that a physiologically functioning tricuspid valve can be constructed from ECM.