multilayer endografts are still an ongoing project but ... · multilayer endografts are still an...

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

Vascular and Endovascular 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


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


introduction

key point is to change the flow

Turbulent Flow

Laminar Flow


• Turbulence increases, significantly, Local pressure and fluid shear stress in the aneurysm: this results in an enlargement and rupture of the vessel

introduction


introduction

• Turbulent Flows Are Naturally Laminated When the Volume of Porosity Reaches 50-65%


introduction

Advantages & Effects of The Lamination MFM®

1 2 3


1_Converting Turbulence to Lamination

• Multilayer Technology Converts Turbulence to Lamination

• With Three-Dimensional Porosity Range of 60-65%


Peak of Wall Shear Stress is an indicator of rupture -PWSS-

Weak Area (rupture)


Streamline: velocity field Surface: von Mises stress


3D Reconstruction

Applied Fluid _ Structure_ Interaction

Flow Velocity Pre & Post

High PWSS at the area of rupture

Reduction of Stress




Flow Velocity Pre & Post



Vorticity Lamination

Without MFM With MFM


Flow Velocity


pre

MFM

po

st M

FM


Applied Fluid _Structure _ Interaction –FSI- Flow Velocity Pre & Post

2_Branches Perfusion by Lamination

23% 24%

Flow Velocity Pattern PRE –MFM®-

Flow Velocity Pattern Post –MFM®-

25% Perfusion Improvement

pre

MFM

po

st M

FM


25% of Increased Blood Flow rate

Kidney Perfusion Improvement of 23 %

2_Branches Perfusion by Lamination


Lamination Effects MFM®

Integration

Endothelialization while keeping

branches perfused

3_Endothelialization while keeping branches perfused


Reinforcement of the wall

(3*) which regulates the

vascular tonus and strength

as a normal wall

Avoids any rupture

Explantation

36 months

(3 years)

Histolgy by NAMSA

Antoine Alves

Elastic lamina

lysis

First In Man (Dec 2006) - Dr M. Henry & Dr A. Polydorou, Athens

(Greece)

3_Endothelialization while keeping branches perfused


Clinical data

Converting Turbulence

to Lamination

Branches Perfusion by

Lamination

Endothelialization while keeping

branches perfused Lam

inar

Flo

w

No aneurysm

rupture risk


Clinical data

Unfortunately MFM is not for all patients


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


Clinical data

MFM different complications type

Severe visceral

ischemia


Clinical data

MFM different complications type

Aneurysm rupture


Clinical data

• Prospective

• Non randomized

• Multicenter

• Approved by the French Health Authority


Clinical data

30 day and 1 year follow-up:

No aneurysm-related mortality


Clinical data

Comparison with volume analisys: STRATO Trial 3 year follow-up (preliminary data) Courtesy C. Vaislic


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


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.


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


conclusion

University of Pavia

Vascular and Endovascular Surgery IRCCS San Martino IST - Genova

Team : Ferdinando Auricchio , Michele Conti, Elena Faggiano, Simone Morganti, Marco Fedele

Team : Domenico Palombo, Giovanni Spinella, Bianca Pane

University of Genova

Computational Mechanics &

Advanced Materials Group

Laboratory of Clinical and Experimental Vascular

Biology

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conclusion

Experimental data Clinical data



conclusion

Specific analysis of patients CT scans:

Total volume, thrombus volume, flow volume

AIM 1)



conclusion

Hemodynamic analysis trough numerical simulations on

geometries patient-specific.

AIM 2)



conclusion

In vitro analysis (patients specific model) of MFM porosity trough

pressure value up-stream and down-stream and collateral vessels

AIM 3)



Technology makes some surgeons better, some others only braver!

Prof. Domenico Palombo

Vascular and Endovascular Unit

IRCCS San Martino – IST

University of Genova - Italy

multilayer endografts are still an ongoing project but ... · multilayer endografts are still an...

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