Ischemic stroke, or a stroke that occurs in the brain, is an acutely time-sensitive disease: The longer it goes untreated, the more likely death or severe brain damage will result. Unfortunately, the current standard for treating ischemic stroke is time-sensitive as well. Patients who experience a stroke are typically treated with a clot-dissolving drug, but the medication must be administered within approximately three hours of the stroke, and it isn’t effective at breaking up large clots. In addition, the drug doesn’t produce significant results for the majority of patients. Patients may not receive the drug in time, and even if they do, it might not work.
Patients have another alternative: a clot retrieval device that pulls or sucks out clots. Such devices may prove more effective for some patients, and may have a longer treatment window than medication. This week, California-based Insera Therapeutics announced that it has been testing the SHELTER (Stroke Help using an Endo-Luminal Transcatheter Embolus Retrieval) device to remove blood clots in the brain. A nickel-titanium mesh basket grabs the clot, which is contained by an outer sheath. The inner part of the device has a soft, spongy tip to prevent the accidental puncturing of blood vessels. The company intends to begin human clinical trials of SHELTER in 2012 or 2013.
Two clot retrieval devices already approved for use in the U.S. are the Merci Retriever and the Penumbra System. Merci, developed by Concentric Medical, features a series of loops attached to a catheter. The loops grab the clot and pull it into the neck, where another catheter sucks the clot out. While the clot is being guided to the second catheter, a balloon is inflated to temporarily stop blood flow and prevent the clot from floating away.
The Penumbra System was approved in the U.S. in late 2007 and is currently being tested in Canada. The device has demonstrated the ability to pull clots from stroke victims up to six hours following the stroke. The Penumbra System involves threading a catheter with an attached suction device from the groin to the brain, and breaking up the clot.
While clot retrieval devices offer advantages over drug therapy, they are not without risks. Once the clots are cleared, blood may rush back into the head and brain bleeding may result. There is also the risk of perforating an artery. Physicians need to determine whether the device is appropriate for each individual patient.
Other companies developing devices to combat various aspects of ischemic stroke include NeuroVasx (treatment for cerebral aneurysms) and EKOS Corporation (endovascular systems to deliver clot-busting drugs). Heard of an innovative stroke-fighting device that hasn’t made it into the mainstream yet? Please share in comments.