Surgery: light – thermal – and electrical application – Light – thermal – and electrical application – Thermal applicators
Reexamination Certificate
2000-05-04
2003-07-15
Gibson, Roy D. (Department: 3739)
Surgery: light, thermal, and electrical application
Light, thermal, and electrical application
Thermal applicators
C606S028000, C604S113000
Reexamination Certificate
active
06592612
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to catheters or cannulae to be used during medical procedures where it is desirable to create a cool or warm environment selectively and more specifically to protect the brain. Hypothermia has been suggested as one of the most potent approaches to both minimizing and therapeutically treating ischemic brain injury. Over the past decade there has been an increased interest in the use of hypothermia as a means for creating a neuroprotective environment during cardiac, cerebrovascular and neurologic surgery, as well as for acute stroke therapy and traumatic head injury. Although not all of the etiological mechanisms are fully understood, hypothermia confers a neuroprotective environment by (1) reducing cerebral metabolism, making the brain more tolerant of reduced blood flow; (2) decreasing excitatory amino acids; (3) stabilizing the blood brain barrier and (4) decreasing heat shock proteins after induced brain injury.
Even though the benefits of cerebral hypothermia have been documented, the widespread use in surgery, neurosurgery, trauma, closed head injury and stroke has not been readily adopted. This lack of adoption is based in large part because of the complications associated with the systemic nature of achieving the hypothermic condition. For example, in cardiac surgery perfusing the entire patient with hypothermic blood from an extracorporeal bypass unit is the common method for obtaining cerebral hypothermia. Using external heat exchangers such as those described in U.S. Pat. No. 5,997,816 to McIntosh et al. and U.S. Pat. No. 5,421,405 to Goddin et al., the teachings of which are hereby incorporated by reference, total body hypothermia can be induced. This modality of hypothermia carries potential risks, including arrhythmias, infection and coagulopathies. To avoid these complications, there has been a trend toward performing cardiopulmonary bypass at normothermic temperatures and using hypothermia in a very selective group of procedures including aortic arch dissections and heart lung transplantation. In addition, topical cooling in the form of ice baths, cooling helmets and cooling blankets have been proposed for cooling the patient's brain in cases of severe head trauma and stroke, however these technologies are inefficient and take too long to be truly effective for rapid cooling of the brain core.
Therefore, what has been needed and heretofore unavailable, is a method and apparatus for selectively cooling the brain apart from the rest of the body in any medical procedure where an ischemic event may or has occurred. By employing novel pumping and cooling devices that require minimal priming volume, along with new methods for controlling patient temperature selectively, the shortcomings of previous medical devices can be overcome. Such methods and devices would offer clinicians significant advantages in managing patients at high risk of neurologic damage, thereby improving outcomes. Furthermore, selective cerebral hypothermic therapy can be used in beating heart cardiac surgery, minimally invasive cardiac surgery, open chest heart surgery, traumatic brain injury, neurosurgery and stroke. The methods and apparatus can be used to extend the therapeutic window for other interventions, can enhance the effects of pharmacological and other co-therapies, as well as provide a neuroprotective environment for aneurysm clipping, coil delivery and other forms of interventional neurology and cardiac surgery.
2. Description of the Background Art
U.S. Pat. No. 5,971,979 to Joye et al. describes a method of delivering compressed cryogenic fluid to the interior of a balloon catheter for selectively freezing a patient's vasculature. U.S. Pat. No. 6,019,783 to Philips, U.S. Pat. No. 4,860,744 to Johnson et al. and U.S. Pat. No. 4,483,341 to Witteles describe thermoelectric cooling systems. U.S. Pat. No. 5,901,783 to Dobak, III describes a cryogenic heat exchanger. U.S. Pat. No. 5,275,595 also to Dobak, III describes a closed cycle cryosurgical instrument. U.S. Pat. No. 5,957,963 to Dobak, III describes a method and apparatus for selective organ hypothermia. U.S. Pat. No. 8,837,003 to Ginsburg describes a method and apparatus for controlling a patient's body temperature by in situ cooling of blood. U.S. Pat. No. 5,794,629 and 5,908,407 to Frazee contemplate the use of catheters for delivering blood flow to selective organs by retrograde perfusion. U.S. Pat. No. 5,820,593 and 5,906,588 to Safar et al. describe methods and apparatus for selectively cooling body organs. Cryogenic fluid sources are described in U.S. Pat. No. 5,644,502 to Little and micropumps are disclosed in U.S. Pat. No. 4,919,647 to Nash, U.S. Pat. No. 5,911,685 to Siess et al., U.S. Pat. No. 5,507,629 to Jarvik, U.S. Pat. No. 4,625,712 and 5,695,471 to Wampler, WO 99/02204 to Aboul-Hosn and WO 99/59652 to Aboul-Hosn. The full disclosures of each of the above US patents are hereby incorporated by reference in their entirety.
SUMMARY OF THE INVENTION
In keeping with the foregoing discussion, the present invention provides novel cooling and perfusion devices, which can be used in a variety of medical procedures, including, but not limited to: stroke, closed head brain injury, trauma, rescusitation, and all forms of general surgery and cardiac surgery. The methods and devices of the present invention include in-line heat exchangers as well as in-line intravascular blood pumps, which reduce priming volume and are compact in design.
In one illustrative embodiment, the present invention provides a fluid transport system, a flexible elongate catheter, and a temperature regulation assembly. The catheter is comprised of three tubular bodies/members, which extend in a substantially coaxial configuration. The tubular members are collectively referred to as a shaft assembly and may be manufactured from metals, alloys, flexible thermoplastic materials, thermoplastic elastomers or thermoset elastomers. More specifically, suitable materials for the shaft assembly include, but are not limited to, PEBAX, PVC, PET, polystyrene, polyvinylchloride, polyurethane, polyethylene, polypropylene, polyamides (nylons), copolymers, polyesters, silicone, latex, and combinations thereof, as well as braided, coiled or counterwound wire reinforcement or filament reinforced composites. Alternatively, or in combination therewith, the shaft assembly or any one of the tubular members may be made of thin walled metallic tubing or hypotube constructed of materials such as stainless steel, platinum, titanium, nitinol alloys and Cobalt alloys such as Elgiloy and Carpenter MP 35.
The innermost tubular member has a delivery lumen that is sized and configured to deliver a heat exchanging medium. There are a variety of heat exchanging mediums that are well known in the art including, but not limited to: water, blood, saline and compressed refrigerants, such as freon, liquid nitrogen or nitrous oxide. A second tubular member has a second lumen/return lumen that is sized and configured to serve as a return for the heat exchanging medium. The first tubular member and the second tubular member together comprise a heat exchanging apparatus that extends at least in part through the outermost tubular member/third tubular member. The outermost tubular member serves as a housing for the heat exchanging apparatus and has an internal lumen/fluid lumen which serves as a fluid lumen. The fluid lumen is isolated from the return lumen creating a heat exchanging interface that facilitates heat exchange between the fluid lumen and the return lumen. Fluid such as blood, water, saline, lysing agents, clot dissolving pharmacological agents, glutamate antagonists, calcium channel blockers, salt based solutions or any other fluid composition or combination may travel over the surface of the second tubular member through the fluid lumen where temperature can be controlled and heat transfer occurs.
A guidewire lumen is also provided to facilitate the insertion of a steerable guidewire. In al
Esch Brady
Lee Mike
Nguyen Hoa
Olsen Eric
Samson Wilfred
Cardeon Corporation
Fulwider Patton Lee & Utecht LLP
Gibson Roy D.
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