Clot extraction devices

Another advantage of angiography during acute stroke treatment is that it allows mechanical disruption of the clot. There are several methods available today. Among them are angioplasty balloons, clot extraction devices (corkscrew retriever MERCI device), ultrasound aided catheters and simple manipulation of the clot... 

The Maitland research group is the leader in developing SMPs for clot-removal devices. In 2002, two studies were reported using thermoset polyurethanes for stroke treatment [45,46]. In the first study, an SMP device was manufactured as a wire that first punctures the clot, is then activated to coil on the distal side of the clot, and is then finally retracted for removal (Fig. 3) [45]. Using an in vitro setup, the prototype devices were shown to activate and hold a porcine blood clot at pressures up to ten times that of the neurovasculature. In a follow up study, laser activation of the shape-memory effect was investigated for the coil clot extraction device along with novel umbrella extraction devices and embolic coils [46]. Laser activation allows the devices to be heated past body temperature to trigger the shape-memory... 

The Penumbra stroke system (Penumbra Inc., San Leandro, CA) includes two different revascularization options (1) thrombus debulking and aspiration may be achieved by a reperfusion catheter that aspirates the clot while a separator device fragments it, and (2) direct thrombus extraction may be performed by a ring retriever while a balloon guide catheter is used to temporarily arrest flow. This system has been tested in a pilot trial in Europe. Twenty patients (mean NIHSS 21) with a total of 21 vessel occlusions (7 ICA, 5 MCA, and 9 Basilar) were treated up to 8 hours after symptom onset. Recanalization prior to lA lysis was achieved in all cases (48% TIMI 2 52% TIMI 3). Seven patients were also treated with lA UK or rt-PA. Good outcome at 30 days (defined as mRS < 2 or NIHSS 4-point improvement) was demonstrated in 42%. The mortality rate was 45%, but there were no device-related deaths. There was one asymptomatic SAH and three symptomatic ICHs. A prospective, single-arm, multicenter trial is being conducted in the United States and Europe currently. 

The results of endotoxin tests for in-process solutions, bulk materials, and finished parenteral products should be reported in the same units as those assigned to the product. Two factors determine the sensitivity of a BET. For infusion solutions and device extracts, the gel-clot sensitivity or the lowest point on the standard curve (lambda for kinetic LAL) and the amount of dilution determine test sensitivity.For products that have an endotoxin limit in EU/mg, the choice of lambda and the concentration of the test material determine sensitivity. The formula for product-specific sensitivity (PSS) is a convenient way to calculate the sensitivity of a BET for this type of product, where ... 

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