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The morning session focused on the delicate problem of networks of mechanical thrombectomy (MT) centers. Marc Ribo pointed out the limits of a regional organization having few comprehensive stroke centers while still performing all MT procedures, since statistics show that morbidity-mortality increases above a certain threshold volume of patients due to further distance and time loss as well as the fatigue of the operators.
As one possible solution to this issue, he proposed the model being used in the Barcelona area in which new comprehensive MT centers are manned by interventionalists from the mothership team on a rotational basis, with the advantage that these new centers are immediately operational.
Jérôme Berge, Laurent Lagarde, Helen Caillez, Louis Veunac and Frederic Boudain gave examples of their organization in the Bordeaux region where one mother-center, the Bordeaux INR team, assured continuous training of peripheral radiologists from two peripheral hospitals in Pau and Bayonne enabling them to do MT locally with seemingly good results in terms of reperfusion results and clinical outcome but required a certain a learning period.
In the recorded thrombus lab in silico demonstration, Course Director Vincent Costalat presented a tool which might be one answer to network problems in the future: with the help of a robot initially developed for coronary procedures he performed a thrombectomy in a flow model. The robot had to be set up by a technician at bedside and femoral access needed to be performed prior to its use. The access to the supra-aortic vessels might also be tricky, and it should be performed by a peripheral radiologist who is on call in the institution.
The neurointerventionist has to proctor the technician in the angiosuite to perform runs or to charge the adequate material into the robot, the specialist can then drive the micro-catheter over the micro-wire using joysticks and a touchscreen until reaching its destination beyond the clot, where it can be deployed and retrieve the stent retriever while the technician assures aspiration. Even if the learning curve seems to be short (about 1 hour), the current version of the robot does not provide any feedback to the operator concerning catheter tension in the catheters and its design is not yet optimized for intracranial procedures since it does not suit a triaxial system.
The robot’s performance could be improved with a guidewire influenced by a magnetic field allowing for more accurate navigation which is beeing developped at the MIT! The problem of the access to the arch might be overcome by using the radial approach systematically.
As for now, robotic thrombectomy is longer than the manual thrombectomy. This is due, in part to the fact that the robot was initially designed to reduce the operator’s radiation exposure, but Prof. Costalat predicts that in the future it could enable us to perform remote neuro-EVT procedures.
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Another interesting presentation was Francisco Mont’Alverde’s case of a refractory stroke from a right carotid T occlusion in a pregnant woman. In this case he was able to treat the patient with a “Y-stenting thrombectomy”, placing the stents respectively in the MCA and ACA. He had to perform another pass with an NeVAt stentriever for an early MCA reocclusion after 10 minutes before finally obtaining a definitive recanalization. Her NIHSS dropped from a pre-procedure 15 to 2 and she was mRS 1 at 3 months follow-up.
Based on this case, Francisco Mont’Alverde argued that rtPA can be administered during pregnancy since a review of the literature found about 30 cases of rtPA administration during pregnancy without any significant toxicity to the fetus. Nevertheless, this is only useful in small vessel occlusions whereas it is not effective in large vessel occlusions, which is an indication for MT.
Using adequate radioprotection, measurement of the fetal exposure show that it was far below the critical threshold.
During the afternoon session, Michael Tymianski gave a very interesting lecture on neuroprotection mediated by a new pharmacological agent, the NA-1. Its action is based on suppressing the oxidative stress after reperfusion by decreasing NO production. After planning and simulating the trials in a primate model, three distinct placebo-controlled trials were performed:
On this first day we also saw four recorded cases of tricky stokes.
The team from the Inselspital of Bern began, presenting an out of guidelines thromboaspiration of a floating clot on a dissected V4 segment of the left vertebral artery. This was immediately repaired by placing a laser-cut Enterprise stent under simple antiplatelet therapy with aspirin.
Their second case was a carotid T occlusion in a very fast progressor which had limited clinical benefit despite a successful and quick TICI 3 recanalization.
This case gave rise to two discussions: in the first about pre-procedure imaging modalities, where Prof. Tudor Jovin defended the position of doing as few imaging procedures as needed to exclude hematoma and transfer the patient as quick as possible to angiosuite. The second one was about the place of IV thrombolysis (IVT) in which it was concluded that existing guidelines should be thought over and IVT might be reserved for residual clots after a partially successful MT.
The Montpellier team demonstrated two anterior circulation stroke cases and how they maximize the first-pass effect by combined use of a balloon-guiding catheter, a distal aspiration catheter and a stent retriever.
…and then it was time for our evening jogging…
Léon IKKA