The Merci Retrieval System
The Merci Retrieval System® from Concentric Medical is a novel, minimally invasive, catheter-based system comprised of three products: the Merci Retriever® , the Merci® Balloon Guide Catheter and the Merci® Microcatheter. The Merci Retrieval System is designed to remove clots and restore blood flow in the neurovasculature, thereby offering hope for ischemic stroke patients who otherwise might have had limited options available to them. The procedure operates through a widely accepted mode of delivery, where the arterial system is accessed through the femoral artery in the groin. The device is then navigated through the body to the brain using standard endovascular techniques.
The FDA granted clearance after reviewing patient data obtained in a clinical study at 25 medical centers in the United States. The MERCI (Mechanical Embolus Removal in Cerebral Ischemia)1 Trial evaluated the device in 141 patients who were ineligible for intervention with IV t-PA, which can only be used within the first three hours of stroke onset.
A subsequent study, the Multi MERCI Trial2 , utilized another generation of retrievers in a multinational trial. The trial evaluated the device in 164 patients, of which 131 were initially treated with the Merci® L5 Retriever. Additionally, in contrast with the MERCI Trial, patients administered IV t-PA were also enrolled.
The Merci Retriever is used in conjunction with the Merci Microcatheter and the Merci Balloon Guide Catheter, and employs standard endovascular techniques. Once the location of the clot has been identified through angiography, the Merci Balloon Guide Catheter is inserted through a small incision in the femoral artery in the groin. Under x-ray guidance, the Merci Balloon Guide Catheter is maneuvered up to the carotid artery in the neck; a guidewire and the Merci Microcatheter are deployed through the Merci Balloon Guide Catheter and then placed just beyond the clot. The physician then deploys the Merci Retriever to engage and ensnare the clot. Once the clot is captured, the Merci Balloon Guide Catheter is inflated to temporarily arrest forward flow while the clot is being withdrawn. The clot is pulled into the Merci Balloon Guide Catheter and completely out of the body, at which point the balloon is deflated and blood flow is restored.
More than 10,000 patients have been treated with the Merci device to date, with over 500 centers performing the procedure worldwide.
The Merci Retriever consists of a family of corkscrew-shaped products that help secure and remove thrombus from large vessels within the neurovasculature. The memory-wire construction allows the Merci Retriever to be delivered through the vasculature in linear form and then returned to its coiled formation following deployment.
There are numerous devices being sold commercially in the United States: the V-Series, the L-Series, which consists of the L4, L5 and L6, and the X6.
The Merci® V Retrievers are Concentric Medical’s newest generation of Retrievers. They are our most efficient retrievers yet. The V Retriever incorporates seven variable pitch loops to better grasp, loosen and pull clots. All five sizes, the V 2.0 Firm, V 2.5 Firm, V 2.5 Soft, V 3.0 Soft and V 3.0 Firm are currently commercially available.
The Merci® L Retrievers are Concentric Medical's second generation of Retrievers. The L Retriever incorporates filaments, or thread-like elements, to provide increased surface area for clot removal. Additionally, the L Retriever has a cylindrical helix design that allows for optimal vessel wall apposition and clot interaction.
The Merci® X6 is Concentric Medical's first generation Retriever. It is a non-filamented retriever, which allows for resheathing in vivo. The lack of filaments also makes this retriever ideal for use in stented vessels.
The Merci Microcatheters are designed to navigate the vasculature and deliver the Merci Retriever to the affected vessel(s) in the brain.
There are currently two Merci Microcatheters on the market: the 14X and 18L. The 14X is compatible with the X6 device while the 18L is compatible with the V and L Retrievers.
Merci Balloon Guide Catheter
The Merci Balloon Guide Catheter is used to facilitate the insertion of the Merci Microcatheter that carries the Merci Retriever close to the affected portion of the brain. It may also be used to provide flow arrest and aspiration for easier clot removal. The Merci Balloon Guide Catheter comes in two diameters, a 9F and a 8F, and two lengths, 80 cm and 95 cm. These are all commercially available in the United States.
The DAC™ family of catheters are a line of highly deliverable, large lumen catheters designed to provide distal access and support for intervention in tortuous anatomy. The DACs are available in multiple sizes to accommodate varying procedural needs.
When used in conjunction with the Merci Retrieval System, DAC provides increased support and decreased vessel deflection during clot retrieval by changing the foce vector to be more in line with the clot face
For additional information, please click here to contact us.
1. Smith WS, Sung G, Starkman S, Saver JL, Kidwell CS, Gobin YP, Lutsep HL, Nesbit GM, Grobelny T, Rymer MM, Silverman IE, Higashida RT, Budzik RF, Marks MP. Safety and Efficacy of Mechanical Embolectomy in Acute Ischemic Stroke: Results of the MERCI Trial. Stroke. 2005 Jul;36(7):1432-1438.
2. Smith WS, Sung G, Saver JL, Budzik RF, Duckwiler G, Liebeskind DS, Lutsep HL, Rymer MM, Higashida RT, Starkman S, Gobin YP, and Multi MERCI Investigators. Mechanical Thrombectory for Acute Ischemic Stroke. Final Results of the Multi MERCI Trial. Stroke (published online ahead of print February 28, 2008).