Stroke clot removal

Alteplase (r-TPA) Activase (Genentech) Acute myocardial infarction pulmonary embolism stroke CVT clot removal... 

The acute ischemic stroke patient may not be competent to make medical decisions. Because emergency treatments (i.e., decompressive surgery, hemorrhage evacuation, thrombolytic drug administration, intraarterial clot removal, emergency endarterectomy) carry... 

Penumbra Pivotal Stroke Trial Investigators (2009) The penumbra pivotal stroke trial safety and effectiveness of a new generation of mechanical devices for clot removal in intracranial large vessel occlusive disease. Stroke 40 2761-2768... 

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 ongoing IMS III trial is a randomized, multicenter, phase III trial continuing the investigation into the efficacy of the combined IV and lA approach to treat acute stroke. Patients are being randomized to IV/IA therapy and IV rt-PA alone in a 2 1 ratio. In the group allocated to combination IV/IA therapy, the physician will select either the EKOS microcatheter or a standard microcatheter to infuse rt-PA, or select the Mechanical Embolus Removal in Cerebral Ischemia (MERCI) clot retrieval device. The primary outcome is the percentage of patients with an mRS score of 0-2 at 90 days. ... 

In situations where inappropriate clot formation results in the blockage of a blood vessel, the tissue damage that ensues depends, to a point, upon how long the clot blocks blood flow. Rapid removal of the clot can often minimize the severity of tissue damage. Thus, several thrombolytic (clot-degrading) agents have found medical application (Table 12.5). The market for an effective thrombolytic agent is substantial. In the USA alone, it is estimated that 1.5 million people suffer acute myocardial infarction each year, and there are another 0.5 million suffer strokes. 

Medical applications of biodegradable shape memory polymers include their use for removing blood clots formed during strokes. Preshaped foams can be used to fill cranial aneurisms. Loosely tied sutures made from fibers that have been stretched at 50 °C will tighten when heated just above room temperature. 

As wounds heal, clots must be removed. The principal agent for dissolving clots is an enzyme called plasmin, which is synthesized as the inactive zymogen called plasminogen. Plasminogen is activated by a number of proteases, the most important of which is tissue-type plasminogen activator (t-PA). t-PA can be extremely effective in initiating the cascade to dissolve the unwanted blood clot involved in stroke or heart attack. 

The MERCl Retriever and Penumbra systems have been approved by the FDA to remove blood clots from the brain in patients experiencing an ischemic stroke. The remaining drugs and devices constitute off-label and/or investigational (precUnical or clinical) usage... 

SMPs represent a major opportunity for the design of MIS devices for the removal of clots from blood vessels to treat ischaemic strokes. A promising approach presented by Maitland et al. (2002) consists of a polyurethane-based device which can be introduced into the thrombus in a rod-like form via a catheter. When activated photothermaUy the device attains a coil- or umbrella-like form capable of trapping the clot, which can then be mechanically removed from the artery, together with the device (Maitland et al., 2002 Metzger et ai, 2002). 

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