Iris Q Grunwald told delegates at the CIRSE annual meeting in early September that she believes she can “achieve better recanalisation rates using mechanical devices that have shown reliable recanalisation rates of about 80%.” Grunwald, from the Acute Vascular Imaging Centre, Biomedical Research Centre, Oxford, UK, spoke at the meeting in Munich on revascularisation techniques, focusing on the more recent mechanical revascularisation concepts.
“It is important to understand how mechanical revascularisation differs from pharmacological revascularisation and devices that have been recently made available for endovascular intracranial thrombectomy show great potential in acute stroke treatment. Compelling evidence of their recanalisation efficacy comes from current mechanical embolectomy trials. In addition to allowing an extension of the conventional therapeutic time window, mechanical recanalisation devices can be used without adjuvant thrombolytic therapy, thus potentially diminishing the intracranial bleeding risk. These devices are particularly suitable in patients in whom thrombolytic therapy is contraindicated and in patients with large vessel occlusion. Intravenous and intra-arterial treatment as well as bridging therapy are viable options in acute stroke treatment,” she said.
Grunwald also noted that while it appeared that mechanical recanalisation devices will have a clinically relevant impact in the interventional treatment of stroke, a randomised study to confirm this was needed. Also, increasingly, the combination of intra-arterial lytics and a mechanical thrombectomy device was being used and may be successful when each single strategy failed, she said.
The designs of the devices vary between their individual engineering concepts and the way they are meant to approach the clots that are causing ischaemia, some need to be proximal to the clot and others, distal, said Grunwald.
Grunwald stated that while there was a host of devices available including the Merci, Phenox, Solitaire, Acandis Aperio and Revive systems, it was important for the operator and staff to be familiar with a few. “I think it helps not having too many devices on the shelf. Choose wisely, because initially there may not be that many stroke cases and it is important to know exactly how they work, and be familiar with their individual differences,” she said.
She noted that in her opinion, good outcomes depended not only on “whether you recanalise but also depends on the time between the onset of the occlusion and the time taken to re-open the vessel.”
As time is of the essence in acute stroke great efforts have been made to streamline workflow and eliminate patient transport between imaging modalities. “We have a combined MR and angio machine which allows the acquisition of high quality MR images during and immediately after a procedure. In other cases we could perform CT perfusion imaging on the angio machine itself. This means you do not have to transport the patient within the hospital, do not need to wait for the radiologist’s report and can switch between imaging modalities during the intervention,” she said.
“I also believe that aftercare plays an important role and that patients must be kept under close supervision to see if there are any further events or complications. If a stroke progresses, the patient should immediately be able to undergo decompressive therapy.”
Grunwald also pointed to patient selection being extremely important. “I will be provocative and state that I do not believe in a fixed time window, but rather a physiological tissue clock. I have seen patients who have been recanalised in one hour and they did not have a good outcome and I have seen patients who have been recanalised after six hours and they went out without any deficits because there were collaterals.”
Grunwald also noted that she did not believe in upper or lower age limits. Especially with regard to the treatment of children, this is a controversial issue. Previous and ongoing stroke trials have conventionally excluded children so guidelines are scarce and do not involve mechanical recanalisation. “To my knowledge mechanical recanalisation device have so far been reported in 21 children and in our cases from Germany achieved good outcomes.
Although the MR images before the procedure often do not look favourable, children seem to have the capacity to recover. It can be tricky to get femoral access, but recanalisation in children is usually a fairly straightforward procedure, she stated.
“I would consider any patient who comes with a fresh occlusion of a major vessel. I would consider bridging therapy and if I do not manage access immediately would like to leave a bolus of 10mg reverse tissue plasminogen activator as a back-up. I like to start without general anaesthesia, because in my experience one loses about 20 minutes to get general anaesthesia. Then, if necessary, the patient can be intubated on the table with my catheter already in place,” she said.