Surgery – Instruments – Means for concretion removal
Reexamination Certificate
2000-11-16
2004-01-20
Nerbun, Peter (Department: 3765)
Surgery
Instruments
Means for concretion removal
Reexamination Certificate
active
06679893
ABSTRACT:
FIELD OF THE INVENTION
The invention is an intracorporeal device and method for grasping objects within a patient's body and withdrawing the grasped objects from the patient's body. More specifically, the intracorporeal device is a grasping device and system for removing an object such as thrombus from a patient's vasculature, particularly the cerebral vascular anatomy, where such an object may cause a debilitating stroke.
BACKGROUND
Several devices and methods have been previously disclosed for removing objects from different regions of the body. Some previous devices and methods, hereafter referred to as “grasping” devices, are intended for grasping or engaging an object where it resides in the body and removing it from that location. These grasping devices are designed to be delivered to the particular site where the target object resides in the body—the object is then engaged by the grasping device and removed from the body. More specific examples of grasping devices have been disclosed for specifically engaging and removing the following from respective body cavities or other locations: gall stones, foreign objects such as implanted medical devices e.g. “snares”, and vascular occlusions such as occlusive thrombi. In one particular device that is disclosed for engaging and removing a calculus principally kidney stones, a grasping assembly includes a plurality of arms arranged in a circumferential pattern in order to capture a target stone to capture the target calculus between them. The device operates via a centrally located plunger that is adjustable longitudinally along proximal tapers of the arms in order to force their detached distal ends apart to open the array for placement around the kidney stone calculus.
Other previously disclosed devices and methods are designed to provide a filter for catching or trapping emboli flowing through a body lumen, such as a blood filter for providing a cage across a blood vessel that is designed to catch debris flowing along the blood vessel downstream from an intervention or other embolic event. Some such filtering devices and methods are intended for removing the caught calculi after it is trapped in the filter. For example, one such known device is a probe-like strainer device that is placed retrograde through a puncture wound in a femoral artery downstream from a peripheral angioplasty site in order to catch emboli flowing downstream from an angioplasty or atherectomy site as a filter. This device includes a plurality of tines that open within the femoral artery in cone shaped arrangement that is constructed specifically for catching emboli flowing into the filter, such as by either providing a sufficiently large number of tines or by providing lateral members extending between adjacent tines to form a web-like strainer structure.
More specific examples of filtering and grasping devices and associated methods targeting specific calculi and the like for removal from various region of the body are disclosed in the following U.S. Patent references:
U.S. Pat. No. 4,612,931 to Dormia; U.S. Pat. No. 4,625,726 to Duthoy; U.S. Pat. No. 4,873,978 to Ginsburg; U.S. Pat. No. 5,064,428 to Cope et al.; U.S. Pat. No. 5,300,086 to Gory et al.; U.S. Pat. No. 5,330,482 to Gibbs et at.; U.S. Pat. No. 5,387,219 to Rappe; U.S. Pat. No. 5,846,248 to Chu et al.; U.S. Pat. No. 5,895,398 to Wensel et al.; U.S. Pat. No. 5,908,435 to Samuels; U.S. Pat. No. 5,944,728 to Bates; U.S. Pat. No. 5,968,057 to Taheri; U.S. Pat. No. 5,972,019 to Engelson et al.; U.S. Pat. No. 6,013,086 to Ouchi et al.; and U.S. Pat. No. 6,027,520 to Tsugita et al.
Recent developments in medical technology and associated treatments have been focused on clearing or removing thromboembolisms or “blood clots” from the cervical and cerebral vasculature in order to treat thromboembolic stroke victims. Thromboembolic stroke is a life threatening condition that consists of arrested blood flow to a region of the brain due to a thromboembolisum blocking a blood vessel feeding that region. Such thrombi often originate in the left heart chambers, break free into the aorta and flow downstream into the cervical neck arteries e.g. carotid arteries, and then ultimately lodge into a narrowed vessel somewhere down the narrowing vascular tree of the cerebral arteries associated with the brain in the head. Once lodged, the thrombus occludes flow along the vessel downstream of the blockage, thus arresting blood flow to the downstream blood vessel and causing the stroke.
Several recent techniques have been disclosed for ablating or “breaking up” a thromboembolism at a cervical or cerebral occlusion location in order to treat stroke. According to one known technique, a standard guidewire, more commonly used to guide medical catheter devices to remote body spaces like a rail, is used to “Dotter” through and break up the occluding clot in order to clear it from the occlusive site. However, fragments of the clot then break free to flow to a downstream site, often still resulting in harmful stroke to other regions of brain tissue. Other more recently disclosed devices and methods are intended to ablate the clot with focused energy delivery, such as for example sonic or laser ablation. However, these techniques also carry the risk of stroking downstream brain tissue. In addition, several of these approaches are very expensive and require specialized hardware to operate the respective ablation catheters.
Several grasping device assemblies and methods have been disclosed specifically for removing thrombi from the cervical and cerebral vessels in order to treat thromboembolic stroke. However, many of these devices have grasping assemblies that are not well adopted for delivery to distal regions of the cerebral vessels where many thromboembolisms are known to cause a debilitating stroke. For example, such known devices are not well designed for delivery to distal cerebral vascular locations through standard cerebral vascular delivery catheters that typically have delivery lumens with very small inner diameters, such as for example through delivery catheters with inner diameters of about 0.042 inch or less, generally adapted to track over a guidewire with an outer diameter of about 0.032 inch or 0.035 inch, or through still smaller delivery catheters with inner diameters of about 0.022 inch, generally adapted to track over a 0.018 inch or less OD guidewire, or through the still smaller standard delivery catheters having inner diameters of about 0.018 inch or less, generally adapted to track over a 0.014 inch OD guidewire. In addition, many of these assemblies and associated methods may not be predictable or easy to operate when engaging and removing an offending blood clot from a cerebral vessel, and particularly from distal cerebral vessels.
Distal cerebral blood vessels typically have inner lumens less than 4 mm and are quite tortuous. For example they have a plurality of 180° bends with a radius of curvature not greater than about 2 cm with spacing between the bends being not greater than about 10 cm. Advancing instruments for therapeutic or diagnostic uses through such anatomy is difficult.
There is a present unmet need for devices for capturing and removing thromboembolisms and other objects from small tortuous body lumens such as distal cerebral vessels.
SUMMARY OF THE INVENTION
This invention is directed to an intracorporeal grasping device and system for capturing an object or mass such as a thromboembolic occlusion in a patient's vasculature and the method of such capturing and removal.
The grasping device has an elongated core member with proximal and distal core sections and a grasping assembly secured to the distal end of the elongated core member which has a plurality of arms circumferentially and preferably uniformly disposed about the longitudinal axis of the grasping device. The proximal ends of the arms are secured to the distal end of the elongated core member. The grasping assembly has contracted and expanded configurations. In the expanded configuration within a body lume
Banner & Witcoff , Ltd.
Chestnut Medical Technologies, Inc.
Nerbun Peter
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