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Ischemic stroke is a devastating, life-altering event affecting over 700,000 people per year in the US alone and is the leading cause of disability in the Western world. The most common event triggering a stroke is a sudden occlusion of a significant blood vessel in the brain (“brain attack”). This causes a lack of blood downstream from the blockage and leads to cell death in the brain and temporary or permanent neurological impairment commonly involving memory, speech and/or movement. Stroke often has a devastating effect on the victims’ ability to work and care for themselves and also presents a large cost burden to families and the healthcare system.
The challenge in stroke treatment is that within minutes of an occlusion of a cerebral artery, brain cells begin to die, creating a non-salvageable region called the infarct core. Most strokes also involve a region of brain tissue which is lacking sufficient oxygen for long term survival, but can be saved if blood flow is restored or augmented. This region, called the penumbra, is the target for all acute stroke treatments.
Current interventions for an acute stroke have limited time windows or involve highly specialized procedures and are treating less than 5% of stroke victims. These stroke treatments focus on dissolving or removing the offending blockage – often a blood clot. Whereas this approach has the potential to reestablish blood flow into the effected cerebral arteries, if it is applied after the surrounding vasculature and brain cells have died, it may pose an even greater risk: cerebral hemorrhage. The common – and only FDA approved treatment for stroke – is the clot-busting drug tPA which must be administered within 3 hours of the onset of stroke symptoms. Additional techniques which involve a catheter advanced into the head and acting at the clot site, such as mechanical removal of the clot or local delivery of tPA, are also in use.
The CoAxia technology is a potential alternative or complement to these clot-focused techniques. The brain has an extensive, interconnected collateral vascular network. Already somewhat active following an ischemic stroke, collateral pathways are capable of further increasing the delivery of oxygenated blood to the stroke’s ischemic penumbra. The ability to salvage that penumbra and minimize the eventual size of the infarct may lead to improved neurological recovery.
CoAxia has developed the NeuroFlo™ catheter as a device for augmenting the blood flow to the brain, and in particular to increase blood flow in the collateral blood vessels to augment perfusion in the ischemic penumbra. NeuroFlo partially restricts blood flow in the descending aorta, diverting blood flow from the lower extremities to the cerebral collaterals. The NeuroFlo catheter itself is a unique, dual-balloon endovascular device. It is inserted through the femoral (leg) artery into the descending aorta and has independently inflatable balloons located immediately above and below the renal (kidney) arteries. The balloons are sequentially inflated to produce occlusions of approximately 70%. The balloons are left inflated for 45 minutes and are then removed and treatment is complete.
This concept was first tested through animal experimentation which demonstrated that partial aortic occlusion could be accomplished without significant side effects, cerebral perfusion could be rapidly and significantly increased, and the size of a resulting infarct could be reduced. In April 2002, the first clinical studies began in humans to demonstrate the safety of the procedure. The images shown on this page (click to enlarge) are taken with a variety of techniques from patients treated with the NeuroFlo catheter.
In 29 stroke patients treated during CoAxia’s feasibility studies 61% of patients improved by more than 3 NIHSS points during the NeuroFlo procedure and 62% had an improvement of 3 NIHSS points at 24 hours. The significance of this improvement is reinforced by the fact that the average time to treatment in these patients was 7.5 hours after the symptom onset - well beyond the 3 Hour treatment window of the FDA-approved intravenous tPA. These feasibility results provided the basis for CoAxia’s current SENTIS pivotal trial, and its recent SafeFlo24 feasibility study (see ongoing clinical trials).
NeuroFlo, as the first device designed to utilize the brain’s own collateral, blood vessels, has a number of potentially important benefits. First, it does not involve intracranial access, instead requiring only a simple aortic placement – a procedure performed at thousands of hospitals throughout the world. In addition, since the therapy does not attempt to remove or disturb the clot, it may be less likely to cause hemorrhage – a common complication of other acute stroke treatments. In fact, current treatments are generally not attempted beyond 3-6 hours post stroke for this reason. NeuroFlo has been evaluated up to 12 hours beyond onset and could become a viable treatment alternative for the hundreds of thousands of patients that are too late to treat with current options. |
