„NextCardio Project and Multilayer Stents – Redefining the Management of Aortic Dissection”, Society for Clinical Vasculat Surgery – Boca Raton, 47th, Annual Symposium, March 16-20, 2019
The management of type B aortic dissection (TBAD) has evolved, and thoracic endovascular aneurysm repair (TEVAR) is safe and life-saving. The ability to remodel the dissected aorta as a result of scaffolding, means that pre-emptive endovascular treatment is being considered and supported by results of the Investigation of Stent Grafts in Aortic Dissection with extended follow-up (INSTEAD-XL) trial and the Acute Dissection: Stent graft OR Best medical therapy (ADSORB)7 trial. An aggressive approach to intervention is driven by evidence that the majority of patients with TBAD will fail medical therapy over time, and patients who undergo aortic intervention have a survival advantage over those treated with medical management alone.
Advancing chronicity of TBAD increases the complexity of the pathologic anatomy, with septal rigidity and false lumen aneurysmal expansion. Multiple adjunctive procedures at the initial treatment and during follow-up are usually necessary, and no clear end point in therapy has yet been defined for patients with residual false lumen flow.
The SMFM is a multilayered cobalt alloy bare metal implantable device. The three-dimensional nature of the SMFM comprises multiple interlocked layers of wire, braided together to create a mesh. This mesh design alters blood flow from turbulent to laminar, inducing positive shear stresses along the aortic wall to promote endothelialization along the luminal aspect of the SMFM and thrombosis of the aneurysm. This device differs from traditional endovascular stent grafts given that it does not completely exclude blood flow from the aneurysm because of its porosity; rather its design alters the rate and direction of blood flow. As long as the branches are fully patent before SMFM implantation, the SMFM permits enhanced blood flow through the mesh wall into native branch arteries, negating the requirement for branching or fenestration to maintain visceral and spinal perfusion.
Out of 876 SMFM implanted globally, we have knowledge of 542. To date, 312 patients are maintained in the global registry, of which 38 patients were identified as having CSAD (12.2%). The study population included 33 male patients (86.8%) and five female patients (13.2%), with a mean age of 60.3 6 13.2 years (range, 26.9-84.8 years). Patients presented with the following: 82% had intercostal and abdominal pain, 15% had disabling claudication, two patients had spinal transient ischemic attacks and paresis, and three patients had hoarseness of voice. All patients were Amer- ican Society of Anesthesiologists IV E; 90% of branches were off the compromised true lumen.
Indications included 35 Stanford type B dissections, two Stanford type A and B dissections, and one mycotic Stan- ford type B dissection. The latter patient had negative blood cultures at the time of the procedure. Fifteen patients (39.5%) had aneurysmal aortas, which were greater than 6 cm in diameter. Fourteen patients (36.8%) were reported to have had a previous aortic repair, including previous TEVAR, endovascular aneurysm repair (EVAR), and aortic arch repair.
All patients had complicated TBAD, which was defined according to Interdisciplinary consensus documents.
There was one case in which the innominate artery was dissected and a case in which both the left carotid and left subclavian arteries were dissected. There were three cases in which the superior mesenteric artery arose from the false lumen, two incidents in which the celiac artery arose from the false lumen, and five cases in which the renal artery was supplied by the false lumen. All the remaining visceral branches arose from the true lumen.
SMFM dissection technique. The dissection technique was employed by the article’s corresponding author and is described so as to assist physicians in the optimal deployment of the SMFM.
All cases are assessed using EndoSize virtual deployment software (Therenva SAS, Rennes, France) with 20% oversizing . The EndoSize software estimates how the SMFM will behave after deployment in terms of expected proximal and distal landing sites. This is crucial to gauge the number of devices required and the device lengths needed for full aortic coverage with minimum overlap of 6 cm in straight aorta and 8 cm in angulated areas.
If a side branch arises from the false lumen, endovascular scissoring using two 12 6 mm balloons, one in the true and one in the false lumen, inflated simultaneously at the confluence of aortic bifurcation and pulled caudally using traction is undertaken to release the tough fibrotic wall from its attachment. An alternative method for septal scissoring is utilising a 12F sheath with two superstiff wires, one in the true lumen and one in the false lumen. The sheath is then gently pushed
Inflating a silicon balloon at the proximal or distal portion of the SMFM will rupture the balloon and so the wire mesh Unballoon (LeMaitre, Burlington, Mass) is preferable for bail out scenarios.
In conclusion,SMFM stabilizes CSAD with no aneurysm formation or disease progression. Overall, false lumen index decreased, while true lumen volume increased. SMFM resulted in freedom from aneurysm rupture, neurologic stroke, paraplegia, and renal failure, while visceral and spinal perfusions were maintained