Finite element modelling of stapled colorectal end-to-end anastomosis: advantages of variable height stapler design.

The impact of surgical staplers on tissues has been studied mostly in an empirical manner. In this paper, finite element method was used to clarify the mechanics of tissue stapling and associated phenomena. Various stapling modalities and several designs of circular staplers were investigated to evaluate the impact of the device on tissues and mechanical performance of the end-to-end colorectal anastomosis. Numerical simulations demonstrated that a single row of staples is not adequate to resist leakage due to non-linear buckling and opening of the tissue layers between two adjacent staples. Compared to the single staple row configuration, significant increase in stress experienced by the tissue at the inner staple rows was observed in two and three rows designs. On the other hand, adding second and/or third staple row had no effect on strain in the tissue inside the staples. Variable height design with higher staples in outer rows significantly reduced the stresses and strains in outer rows when compared to the same configuration with flat cartridge.

Mechanical properties of mitral allografts are not reasonably influenced by cryopreservation in sheep model.

A mitral allograft is used exceptionally in the mitral, as well as in the tricuspid position, mostly as an experimental surgical procedure. The authors decided to evaluate the possibility of inserting a cryopreserved mitral allograft into the tricuspid position in a sheep experimental model. Within the framework of this experimental project the mechanical properties of the cryopreserved mitral allograft were tested. A novel methodology studying the functional unit composed of mitral annulus, leaflet, chordae tendinaea, and papillary muscle is presented. A five-parameter Maxwell model was applied to characterize the viscoelastic behavior of sheep mitral valves. A control group of 39 fresh mitral specimens and a test group of 13 cryopreserved mitral allografts from tissue bank were tested. The testing protocol consisted of six loading cycles with 1 mm elongation every 5 min. There was no significant difference in the mean values of the determined parameters (p>0.05) which confirms the main hypothesis that cryopreservation does not influence significantly material parameters characterizing the tissue mechanics. Slight discrepancy is observed in variances of viscous parameters suggesting that the values of the test group may be spread over larger interval due to the treatment.

[Report on 3061 laparoscopic cholecystectomies]. / Zpráva o 3061 laparoskopických cholecystektomiích.

The results of 3061 laparoscopic cholecystectomies made by 58 surgeons in nine departments--feasibility 88.9%, low morbidity rate (n = 2071) 11.8%, high morbidity rate 2.48%, mortality rate 0.22%, residual choledocholithiasis 1.36%, preoperative use of endoscopic methods 1.0%, revision in a total of 1.8%--are as a rule less favourable than summarized statistical data from abroad. Similarly as in data abroad the incidence of biliary lesions is not satisfactory--0.65%. The incidence of fistulas (0.13%) revisions on account of haemorrhage (0.29%) and surgical preoperative accidents (0.24%) was lower. Departments which use thermocoagulation have a significantly lower incidence of lesions (0.14% - p < 0.06) than teams working with electrocoagulation.