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Multilayer Endografts are still an ongoing project but with a grounded scientific rationale Prof. Domenico Palombo Vascular and Endovascular Unit IRCCS San Martino – IST University of Genova - Italy introduction • It’s a tubular, radiopaque, self-expandible bare stent. • It consists of multilayer (3-5) braided wires made of a chrome and cobalt alloy • Cobalt resistance to corrosion, compatible with MRI • The wires are curved at each point of intersection prevent friction and preserve the shape • The two interconnected layers increase the anular resistance and the radial elasticity • The best result is achieved at a 65% porosity Vascular and Endovascular IRCCS San Martino – IST University of Genova - Italy introduction • Longitudinal flexibility and low profile • allows the penetration through tortuous/winding vessels • 20 Fr aortic • 8-12Fr peripheral • Multilayer 3D structure • Tougher/more resistant • Prevent myointimal hyperplasia • Great expansion rate self fixing on arterial wall no migration • Design • • • • Consists in a radiopaque guiding catheter. For peripheral use the delivery system can accommodate a 0,025 inch guide-wire The stent can be removed or repositioned when <80% of its length has been extruded Access preferentially from the femoral artery Vascular and Endovascular IRCCS San Martino – IST University of Genova - Italy introduction key point is to change the flow Turbulent Flow Laminar Flow Vascular and Endovascular IRCCS San Martino – IST University of Genova - Italy introduction • Turbulence increases, significantly, Local pressure and fluid shear stress in the aneurysm: this results in an enlargement and rupture of the vessel Vascular and Endovascular IRCCS San Martino – IST University of Genova - Italy introduction • Turbulent Flows Are Naturally Laminated When the Volume of Porosity Reaches 50-65% Vascular and Endovascular IRCCS San Martino – IST University of Genova - Italy introduction Advantages & Effects of The Lamination MFM® 1 2 3 Vascular and Endovascular IRCCS San Martino – IST University of Genova - Italy 1_Converting Turbulence to Lamination • Multilayer Technology Converts Turbulence to Lamination • With Three-Dimensional Porosity Range of 60-65% Vascular and Endovascular IRCCS San Martino – IST University of Genova - Italy 1_Converting Turbulence to Lamination Peak of Wall Shear Stress is an indicator of rupture -PWSS- Streamline: velocity field Surface: von Mises stress Weak Area (rupture) Vascular and Endovascular IRCCS San Martino – IST University of Genova - Italy 1_Converting Turbulence to Lamination Applied Fluid _ Structure_ Interaction Flow Velocity Pre & Post 3D Reconstruction High PWSS at the area of rupture Reduction of Stress Vascular and Endovascular IRCCS San Martino – IST University of Genova - Italy 1_Converting Turbulence to Lamination Applied Fluid _ Structure_ Interaction Flow Velocity Pre & Post Vascular and Endovascular IRCCS San Martino – IST University of Genova - Italy 1_Converting Turbulence to Lamination Applied Fluid _ Structure_ Interaction Flow Velocity Lamination pre MFM post MFM Vorticity Without MFM With MFM Vascular and Endovascular IRCCS San Martino – IST University of Genova - Italy 2_Branches Perfusion by Lamination Applied Fluid _Structure _ Interaction –FSIFlow Velocity Pre & Post Flow Velocity Pattern Post –MFM®- 23% 25% Perfusion Improvement 24% Vascular and Endovascular IRCCS San Martino – IST University of Genova - Italy post MFM pre MFM Flow Velocity Pattern PRE –MFM®- 2_Branches Perfusion by Lamination Kidney Perfusion Improvement of 23 % 25% of Increased Blood Flow rate Vascular and Endovascular IRCCS San Martino – IST University of Genova - Italy 3_Endothelialization while keeping branches perfused Lamination Effects MFM® Integration Endothelialization while keeping branches perfused Vascular and Endovascular IRCCS San Martino – IST University of Genova - Italy 3_Endothelialization while keeping branches perfused Explantation 36 months (3 years) Histolgy by NAMSA Antoine Alves Reinforcement of the wall (3*) which regulates the vascular tonus and strength as a normal wall Elastic lamina lysis Avoids any rupture First In Man (Dec 2006) - Dr M. Henry & Dr A. Polydorou, Athens (Greece) Vascular and Endovascular IRCCS San Martino – IST University of Genova - Italy Laminar Flow Clinical data Converting Turbulence to Lamination Branches Perfusion by Lamination Endothelialization while keeping branches perfused No aneurysm rupture risk Vascular and Endovascular IRCCS San Martino – IST University of Genova - Italy Clinical data Unfortunately MFM is not for all patients Vascular and Endovascular IRCCS San Martino – IST University of Genova - Italy Clinical data MFM different complications type Aortic arch rupture after multiple multilayer stent treatment of a thoracoabdominal aneurysm Ferrero E, Gibello L, Ferri M, Viazzo A, Nessi F. J Vasc Surg. 2013 Nov 4. Aortic Arch Rupture Vascular and Endovascular IRCCS San Martino – IST University of Genova - Italy Clinical data MFM different complications type Severe visceral ischemia Vascular and Endovascular IRCCS San Martino – IST University of Genova - Italy Clinical data MFM different complications type Aneurysm rupture Vascular and Endovascular IRCCS San Martino – IST University of Genova - Italy Clinical data • • • • Prospective Non randomized Multicenter Approved by the French Health Authority Vascular and Endovascular IRCCS San Martino – IST University of Genova - Italy Clinical data 30 day and 1 year follow-up: No aneurysm-related mortality Vascular and Endovascular IRCCS San Martino – IST University of Genova - Italy Clinical data Comparison with volume analisys: STRATO Trial 3 year follow-up (preliminary data) Courtesy C. Vaislic Vascular and Endovascular IRCCS San Martino – IST University of Genova - Italy Clinical data Natural History of thoracoabdominal aneurysms Elefteriades JA(1), Farkas EA. Thoracic aortic aneurysm clinically pertinent controversies and uncertainties. J Am Coll Cardiol. 2010 Mar 2;55(9):841-57 Italian experience and STRATO Trial No mortality related to TAAA and Juxtarenal aortic aneurysm rupture during follow-up Vascular and Endovascular IRCCS San Martino – IST University of Genova - Italy conclusion Organized Laminar Thrombi of the aneurysm over time Improves flow up to 20% into vital branches. Endothelization of multilayered mesh occurs over time allowing the aneurysm to shrink. Vascular and Endovascular IRCCS San Martino – IST University of Genova - Italy conclusion @Short and mid-term results seem to be encouraging even compared with the results of branched and fenestrated endograft @Preoperative accurate planning and Follow-up is important as it is for the treatment with branched or fenestrated endograft @Some patients cannot be treated with MFM because of unfavorable anatomy @However, prospective studies are needed with larger series and longer follow-up @Finally, coupling between experimental and clinical data Vascular and Endovascular IRCCS San Martino – IST University of Genova - Italy conclusion University of Pavia Computational Mechanics & Advanced Materials Group Team : Ferdinando Auricchio , Michele Conti, Elena Faggiano, Simone Morganti, Marco Fedele University of Genova Laboratory of Clinical and Experimental Vascular Biology Team : Domenico Palombo, Giovanni Spinella, Bianca Pane Vascular and Endovascular Surgery IRCCS San Martino IST - Genova Vascular and Endovascular IRCCS San Martino – IST University of Genova - Italy conclusion Experimental data Clinical data Vascular and Endovascular IRCCS San Martino – IST University of Genova - Italy conclusion AIM 1) Specific analysis of patients CT scans: Total volume, thrombus volume, flow volume Vascular and Endovascular IRCCS San Martino – IST University of Genova - Italy conclusion AIM 2) Hemodynamic analysis trough numerical simulations on geometries patient-specific. Vascular and Endovascular IRCCS San Martino – IST University of Genova - Italy conclusion AIM 3) In vitro analysis (patients specific model) of MFM porosity trough pressure value up-stream and downstream and collateral vessels Vascular and Endovascular IRCCS San Martino – IST University of Genova - Italy Technology makes some surgeons better, some others only braver! Prof. Domenico Palombo Vascular and Endovascular Unit IRCCS San Martino – IST University of Genova - Italy Vascular and Endovascular IRCCS San Martino – IST University of Genova - Italy