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Prof. Franziska Dorn, Head of Neurointervention at Bonn University Hospital, Germany
Experience the viewpoint and expertise of Prof. Franziska Dorn as she reveals her insights during the interview with Dr. Jildaz Caroff.
What motivated you to incorporate the Cerenovus Nimbus™ Stentriever into your clinical practice, and how has it impacted your patient outcomes compared to other thrombectomy devices?
Today, we have reached the point where we are technically successful in the vast majority of all thrombectomies. Unfortunately, however, there are always patients in whom we fail and do not achieve recanalization. This is annoying and frustrating for the treating physician, but most important associated with a low chance for a favorable clinical outcome for the patients. We have used Nimbus™ in over 60 cases where our conventional technique did not result in recanalization success. Nimbus™ has led to sufficient recanalization in more than 50% of these cases, and in combination with other techniques even in more than 70%. This is in line with the experience from other colleagues and with the data from the SPERO registry. If you want, Nimbus™ gives patients an extra chance of more than 50% after conventional thrombectomy techniques have failed.
Can you describe any unique features or advantages of the Cerenovus Nimbus™ Stentriever that differentiate it from other stentrievers available in the market?
First, Nimbus™ is not a conventional stent retriever, but it was designed to specifically target clots that are poor in red blood cells and rich in fibrin. These clots tend to be more rubbery and stiffer and are usually difficult to retrieve. The device combines a distal classical stent retriever and a proximal spiral section, which is deployed at the level of the clot. After deployment of the device, a pinching maneuver has to be performed by re-advancing the microcatheter; subsequently, the spiral cells close and grip the clot and ideally remove it.
In your experience, what types of ischemic stroke cases have you found the Cerenovus Nimbus™ Stentriever to be particularly effective for? Are there any specific patient characteristics that indicate its use?
Initially, when we started with the Nimbus™ device, we only used it after failure of standard techniques (in most cases stent retriever in combination with distal aspiration), but found that there are some cases where it works perfectly as a first-line device. The main problem is that we currently do not have valid methods to predict the composition of the thrombus before we start our intervention. However, some factors such as atrial fibrillation, Covid, calcification on the initial CT scan and difficulty to pass the clot with the microwire may indicate that clot removal will be challenging. In these cases, we have achieved good first-pass results with the Nimbus™ when used as a first-line device. I hope that we will in the future have better methods to predict the clot composition and more information on which technique works best in specific situations.
Are there any challenges or limitations you have encountered when using the Cerenovus Nimbus™ Stentriever? If so, how have you addressed them or modified your approach to overcome these challenges?
The most difficult situation still is when Nimbus™ also fails after conventional techniques. In my center, we have some cases where direct aspiration was then successful or also the combination of Nimbus™ with a classical stent retriever if the clot is located in a bifurcation. If all clot removal attempts fail, there is only one option to potentially improve the patient and this is permanent stenting.
Have you noticed any specific procedural techniques or tips that have optimized your success rate when utilizing the Cerenovus Nimbus™ Stentriever? Are there any key learnings or best practices you can share with other practitioners?
The pinching technique is not new, but when using Nimbus™, it is mandatory in order to allow the struts to grab and remove the clot. When the microcatheter reaches the clot, resistance is felt in most, but not in all cases and then it is unclear whether the clot is trapped or not. One tip is then to see if the entire system slightly straightens up and also that the guiding catheter comes up a little but under fluoroscopy, both indicating that the pinching maneuver is working.
In general, the chance of reaching a good recanalization result decreases significantly after one or two failed passes, so it simply does not make much sense to continue with the same technique. In my practice, I switch to Nimbus™ or another innovative technique such as dual-stent retriever technique after not more than two failed passes with classical techniques.
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