Experimental acute type B aortic dissection: different sites of primary entry tears cause different ways of propagation.

BACKGROUND: Many dissections seem to also have a retrograde component. The aim of the study was to evaluate different sites of primary entry tears and the propagation of the dissecting membrane, antegrade and retrograde, in an experimental model of acute type B aortic dissection. METHODS: The entire thoracic aortic aorta including the supraaortic branches was harvested from 26 adult pigs. An intimal tear of 15 mm was created by contralateral incisions sites 20 mm downstream the origin of the left subclavian artery. In 13 cases the dissection was created at the concavity and in 13 cases at the convexity. The aortic annulus was then sewn into a silicon ring of a driving chamber. The distal aorta was connected to a tubing with adjustable resistance elements. The circulation was driven by the pneumatically driven Vienna heart to mimic aortic flow and pressure. RESULTS: Mean circulation time was 64 ± 45 minutes. A mean pressure of 152 ± 43 mm Hg and a mean flow of 4.5 ± 1.0 L/minute were reached. The median antegrade propagation length of the dissecting membrane was 65 mm. The median retrograde propagation length in primary entry tears at the convexity was 20 mm and was stopped by the left subclavian artery. In aortas with the primary entry tear at the concavity, median retrograde propagation length was 21 mm extending up to the ascending aorta in 16%. CONCLUSIONS: In this experimental model of acute type B aortic dissection, we confirmed that many type B dissections do also have a retrograde component. At the convexity, this component is stopped by the left subclavian artery as an anatomic barrier. At the concavity, the propagation of the dissecting membrane may extend up to the ascending aorta and may therefore cause retrograde type A dissection. These findings may substantiate clinical need for treatment of type B dissections with a primary entry tear at the concavity.

Mesh fixation in laparoscopic incisional hernia repair: glue fixation provides attachment strength similar to absorbable tacks but differs substantially in different meshes.

BACKGROUND: Laparoscopic ventral hernia repair has gained popularity among minimally invasive surgeons. However, mesh fixation remains a matter of discussion. This study was designed to compare noninvasive fibrin-glue attachment with tack fixation of meshes developed primarily for intra-abdominal use. It was hypothesized that particular mesh structures would substantially influence detachment force. STUDY DESIGN: For initial evaluation, specimens of laminated polypropylene/polydioxanone meshes were anchored to porcine abdominal walls by either helical titanium tacks or absorbable tacks in vitro. A universal tensile-testing machine was used to measure tangential detachment forces (TF). For subsequent experiments of glue fixation, polypropylene/polydioxanone mesh and 4 additional meshes with diverse particular mesh structure, ie, polyvinylidene fluoride/polypropylene mesh, a titanium-coated polypropylene mesh, a polyester mesh bonded with a resorbable collagen, and a macroporous condensed PTFE mesh were evaluated. RESULTS: TF tests revealed that fibrin-glue attachment was not substantially different from that achieved with absorbable tacks (median TF 7.8 Newton [N], range 1.3 to 15.8 N), but only when certain open porous meshes (polyvinylidene fluoride/polypropylene mesh: median 6.2 N, range 3.4 to 10.3 N; titanium-coated polypropylene mesh: median 5.2 N, range 2.1 to 11.7 N) were used. Meshes coated by an anti-adhesive barrier (polypropylene/polydioxanone mesh: median 3.1 N, range 1.7 to 5.8 N; polyester mesh bonded with a resorbable collagen: median 1.3 N, range 0.5 to 1.9 N), or the condensed PTFE mesh (median 3.1 N, range 2.1 to 7.0 N) provided a significantly lower TF (p < 0.01). CONCLUSIONS: Fibrin glue appears to be an appealing noninvasive option for mesh fixation in laparoscopic ventral hernia repair, but only if appropriate meshes are used. Glue can also serve as an adjunct to mechanical fixation to reduce the number of invasive tacks.