LVAD Inflow Cannula Covered with a Titanium Mesh Induces Neointimal Tissue with Neovessels

Abstract

Background Thrombus formation at the interfaces of inflow cannulas and left ventricular apexes is considered to be one of the predominant sources of thromboembolic complication. Use of a fine titanium mesh-covered inflow cannula is expected to prevent such thrombus formation by inducing neointimal tissue around the cannula. Methods Titanium pins (20 mm long, 3 mm diameter) covered with a fine titanium mesh (wire dia. 85 μm; volumetric porosity 40–70%) were developed to mimic the inflow cannulas of left ventricular assist devices (LVADs). Smooth-surface pins of the same size were also designed. The pins were implanted into the left ventricular apexes of rabbits. The rabbits were bled without anticoagulation for between 1 week and 1 year. The tissues around the pins were evaluated histologically. Results 28 rabbits (mesh group, 15; smooth group, 13) were evaluated. The mesh-covered pins inhibited thrombus formation to a remarkable degree throughout the entire observation period. The tissues around the mesh-covered titanium pins appeared to be in the process of conversion from thrombus formation to granulation, resulting in the replacement of fibrotic tissue containing myofibroblasts with endothelialized and angiogenic tissue. On the surface of the mesh-covered pins, endothelial cells were arranged without platelet adhesion. The tissue formed around the smooth-surface pins was partially organized into a thrombus without angiogenesis. Conclusions The titanium-mesh surface modification prevented thrombus formation with formation of neointimal tissue with endothelialization and angiogenesis. This surface modification could prevent wedge thrombus formation among patients supported by LVADs.