Surgery – Miscellaneous – Methods
Reexamination Certificate
2000-08-17
2002-12-31
Isabella, David J. (Department: 3738)
Surgery
Miscellaneous
Methods
C623S001310, C623S001510, C623S902000, C604S008000, C606S194000, C606S200000
Reexamination Certificate
active
06499487
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to aortic diverters for temporary or permanent placement in the aorta in order to divert embolic material away from the arteries that carry blood to the brain, i.e., the carotid or cerebral arteries (including the brachiocephalic trunk, the left common carotid, and the left subclavian; Anne R. Agur, Grant's Atlas of Anatomy 52 (9th ed., Williams & Wilkins 1991) (1943) (this and all other references cited herein are expressly incorporated by reference as if set forth in their entirety in this disclosure)). More particularly, the invention relates to aortic diverters placed within the ascending aorta, either temporarily or permanently, such that embolic debris entering the aorta are carried through or past the diverter and past the carotid arteries, thus being diverted away from cerebral blood vessels. The present invention also relates to methods of protecting patients against cerebral embolization by using aortic diverters.
BACKGROUND OF THE INVENTION
Preventing emboli from entering the carotid arteries- (i.e., the brachiocephalic, the left common carotid, and the left subclavian) by way of the aorta reduces the incidence of ischemic stroke. Emboli in the aorta come from several sources. These sources include: 1) aortic atheroma which detaches from the wall of the aorta due to various reasons including incising, clamping, and/or clamp release of the aorta during surgery (see, Barbut et al., “Cerebral Emboli Detected During Bypass Surgery Are Associated With Clamp Removal,” Stroke, 25(12):2398-2402 (1994)); 2) thrombus which forms in the right atrium resulting from atrial fibrillation; 3) thrombus which forms on ventricular assist devices; 4) venous thrombus which passes into the left ventricle through a patent foramen ovale or other arteriovenous shunt; and 6) other less common sources.
There are a number of known devices designed to filter blood (see, e.g., Barbut et al., International Application No. PCT/US97/12751, and Barbut et al., U.S. Pat. No. 5,662,671), but no known devices designed to divert or redirect emboli past the carotid arteries. Using careful surgical techniques, the chance of an embolic event causing harm to the patient by way of cerebral embolization is so low that emboli managing devices have not been considered. Thus, there are no known solutions to minimizing the probability of cerebral embolization; except for reducing the amount of emboli released into the blood stream by careful handling of blood vessels.
On the venous side of the circulatory system, implantable vena cava filters reduce the incidence of pulmonary embolism, but they only trap large emboli, and they have a tendency to become clogged as they accumulate material. For example, Cottenceau et al., U.S. Pat. No. 5,375,612 discloses a blood filter intended for implantation in a blood vessel, typically in the vena cava. This device comprises a zigzagged thread wound on itself and a central strainer section to retain blood clots. Another example is Lefebvre, French Patent No. 2,567,405, which discloses a blood filter for implantation by an endovenous route into the vena cava. The filtering means may consist of a flexible metallic grid, a flexible synthetic or plastic grid, a weave of synthetic filaments, or a non-degradable or possibly biodegradable textile cloth.
There are very few intravascular devices designed for arterial and especially aortic filtration, much less diversion. A filter that functions in arteries must address additional concerns because of the hemodynamic differences between arteries and veins. Arteries are much more flexible and elastic than veins and, in the arteries, blood flow is pulsatile with large pressure variations between systolic and diastolic flow. These pressure variations cause the artery walls to expand and contract. Thus, filters and diverters must be able to expand and contract along with the lumen of the aorta to which they may be anchored.
The problem of preventing emboli from reaching the cerebral vasculature has thus far not been adequately addressed. Therefore, a need exists for new devices and methods to prevent embolic material from entering the carotid/cerebral arteries, while maintaining peripheral blood flow from the heart to the descending aorta.
SUMMARY OF THE INVENTION
The present invention relates to aortic diverters and methods of diverting or redirecting emboli away from the carotid arteries to prevent cerebral embolization. The invention includes safe aortic diverters positionable in the ascending aorta in order to divert embolic material of all sizes away from the carotid arteries, thereby washing emboli downstream into the thoracic and peripheral vasculature. The devices of the present invention are adapted to be placed in the ascending and transverse aorta in order to divert embolic material away from the carotid arteries. This embolic matter includes but is not limited to atheromatous fragments or material, thrombus, globules of fat, air bubbles, clumps of bacteria and/or other foreign matter, tumor cells, or any other bits of tissue. The aortic diverters of the present invention can be placed surgically, endoscopically or percutaneously, and either permanently or temporarily.
In one embodiment of the invention the aortic diverter includes two components. The first component is a hollow tube, which is substantially cylindrical, conical or frustoconical in shape. The hollow tube is an appropriate size to fit within the lumen of the ascending aorta. The proximal end of the hollow tube is adapted to fill the lumen of the aorta so that substantially all blood entering the ascending aorta from the heart must travel through the hollow tube in order to continue past the ascending aorta and into the other arteries leading to the rest of the human body. The second component is an anchoring mechanism for securing the hollow tube to the lumen of the aorta.
In another embodiment the aortic diverter also includes two components. The first component is a hollow tube, which is substantially cylindrical, conical or frustoconical in shape. The hollow tube is an appropriate size to fit within the lumen of the ascending aorta. The proximal end of the hollow tube is adapted to fill the lumen of the aorta so that substantially all blood entering the ascending aorta from the heart must travel through the hollow tube in order to continue past the ascending aorta and into the other arteries leading to the rest of the human body. The second component is a sleeve secured to the proximal end of the hollow tube. The sleeve can be substantially rigid and circumferentially sized to frictionally anchor the hollow tube to the lumen of the aorta.
In another embodiment, the aortic diverter is a flat, planar, snowshoe device that can be placed across the apex of the aorta in order to prevent emboli from flowing into the carotid arteries. The snowshoe diverter comprises a planar tongue and a handle, and can also include supports or legs mounted on either or both sides of the tongue. The handle is attached to the proximal end of the tongue for convenient connection to an introducing device such as a cannula, and is also useful for easy orientation and placement of the snowshoe diverter within the aorta. The handle itself can be hollow, thus acting as a cannula to supply filtered blood to the carotid arteries as well as the descending aorta. The hollow cannulated handle can be attached to the tongue such that blood flowing out of the handle and into the aorta is partitioned by the tongue to flow either anterior or posterior the tongue. Alternatively, the cannulated handle can be attached to the tongue so that all blood flowing out of the handle and into the aorta flows anterior the tongue. Alternatively, the cannulated handle can be attached to the tongue so that all blood flowing out of the handle and into the aorta flows posterior the tongue. Alternatively, the handle can be solid with no lumen for blood flow. The handle can also be flexible and bendable in order to move the handle out of the way of the sur
Hattori Sachiko
McKenzie John
Chattopadhyay Urmi
Embol-X Inc.
Isabella David J.
O'Melveny & Myers LLP
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