Markets: Stroke
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"Time is brain". To a person afflicted by stroke, nothing is more important than time. Every second that passes leads to decreased brain function. The “time window” during which intervention can be beneficial lasts about nine hours:
NIT was founded by three world renowned medical professionals who realized that simpler and easier to use thrombectomy devices could potentially have a dramatic effect on patient outcomes.
We are currently testing a device that delivers benefits through:
- fast access
- quick recanalization
- complete removal of thrombus from the MCA
The NIT device achieves these goals by means of:
- Carotid or radial access, as well as conventional femoral access
- Novel use of thrombolytics
- Near instantaneous recanalization through proprietary mechanisms
- Aspiration of the clot through shorter catheter system
Fast access and recanalization are extremely important parameters: a recent review of over 600 patients in the MERCI and multi-MERCI registries showed that for the patients that were recanalized, shorter procedure times led to twice the likelihood of good outcomes at 90 days
Figure 1: Schematic representation of arteries in the brain
The middle cerebral artery (MCA) is part of the Circle of Willis (Figure 1) that supplies blood to the brain. It is the largest branch of the internal carotid that supplies blood to a portion of the frontal lobe and the lateral surface of the temporal and parietal lobes, including the primary motor and sensory areas of the face, throat, hand and arm and in the dominant hemisphere, the areas for speech. Since the middle cerebral artery serves as the pathway for blood flow from the heart to the brain, any disruption of blood flow results in stroke.
Stroke is the second leading cause of death and the most frequent cause of permanent disability in the world. Approximately 29% of patients die within 1 year following a stroke; this percentage rises in patients older than 65 years. 31% of stroke survivors need help in taking care of themselves after a stroke, 20% need some type of assistance for walking, and 16% need to be placed in some form of institution providing assisted living. At least one third of stroke survivors suffer from depression. Any intervention that can reduce the incidence of these devastating effects will be embraced by the medical community and general public.
The two basic types of stroke are ischemic (blockage) and hemorrhagic (bleeding). A hemorrhagic stroke is a rupture of the artery that results in arterial bleeding within the brain. Ischemic strokes result from blockage of the arteries that supply blood to the brain. The blockage usually results when a blood clot travels through the bloodstream, and lodges in cerebral arteries as shown in Figure 2. The middle cerebral artery is the most frequent site of ischemic strokes.
The two basic types of stroke are ischemic (blockage) and hemorrhagic (bleeding). A hemorrhagic stroke is a rupture of the artery that results in arterial bleeding within the brain. Ischemic strokes result from blockage of the arteries that supply blood to the brain. The blockage usually results when a blood clot travels through the bloodstream, and lodges in cerebral arteries as shown in Figure 2. The middle cerebral artery is the most frequent site of ischemic strokes.
Figure 2: Occurrence of an ischemic stroke in the middle cerebral artery
Figure 3: Prevalence of Health Conditions by Age Group (U.S.), 2004-2005
In the United States, approximately 750,000 strokes occur each year, including both new and recurrent cases. Of the yearly stroke occurrences, approximately 84% are ischemic strokes. By the year 2050, the annual number of strokes is expected to reach 1 million. Currently, more than 4.4 million people in the United States are stroke survivors. Of those who survive their first stroke, it is estimated that nine in 10 will have long term impairment of movement, sensation, memory or reasoning, ranging from slight to devastating.
Stroke affects people of all ages as shown in Figure 3.
Ischemic Stroke ManagementStroke affects people of all ages as shown in Figure 3.
Ischemic strokes are treated by removing the obstruction and restoring blood flow to the brain using non-mechanical or mechanical methods. Timing is critical in treating ischemic stroke victims as permanent disability or death can occur within hours of the initial blockage.
Non-Mechanical Device Treatment
In the past, a clot-dissolving (thrombolytic) drug called tissue Plasminogen Activator (tPA) was used to treat ischemic stroke patients. However, when given intravenously, it is not very efficient because the drug is diluted throughout the body and only a small portion actually reaches the blood clot in the middle cerebral artery. Moreover, to be effective, a thrombolytic drug must be administered intravenously within 3 hours of the onset of an ischemic stroke. However, most people who have had a stroke typically arrive at the hospital between 3 to 9 hours afterward - too late to be given a thrombolytic drug intravenously. There have also been reports of risk of symptomatic hemorrhage by this treatment. Due to these limitations, fewer than 5% of stroke patients in the U.S. receive tPA treatment.
Mechanical Device Treatment
The goal of mechanical device treatment is to quickly restore cerebral blood flow in the involved territory with or without the use of any clot dissolving drugs. This process involves insertion of a guide wire with a radiopaque tip into a small incision over the artery in the groin (femoral artery) where local anesthesia is administered. The catheter, a long thin tube that contains the device is guided to the blockage site using x-ray (angiographic) imaging. The device extends distal to the catheter to remove the clot. The mechanical devices employing the above process are commonly known as Endovascular devices for stroke management.