Surgery – Means for introducing or removing material from body for... – Material introduced into and removed from body through...
Reexamination Certificate
2000-05-19
2003-11-11
Hayes, Michael J. (Department: 3763)
Surgery
Means for introducing or removing material from body for...
Material introduced into and removed from body through...
C604S096010, C523S113000, C424S423000
Reexamination Certificate
active
06645167
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention is directed to novel methods for embolizing blood vessels which are particularly suited for treating aneurysms, AVM and high flow fistulas. In one embodiment, the compositions employed in the methods of this invention comprise a biocompatible polymer, a biocompatible solvent and a biocompatible contrast agent wherein the viscosity of this composition is at least about 150 cSt at 40° C. and, preferably, at least 200 cSt at 40° C.
2. References
The following publications are cited in this application as superscript numbers:
1
Mandai, et al., “Direct Thrombosis of Aneurysms with Cellulose Acetate Polymer”,
J. Neurosurg
., 77:497-500 (1992)
2
Kinugasa, et al., “Direct Thrombosis of Aneurysms with Cellulose Acetate Polymer”,
J. Neurosurg
., 11:501-507 (1992)
3
Casarett and Doull's
Toxicology
, Amdur et al., Editors, Pergamon Press, New York, pp. 661-664 (1975)
4
Greff, et al., U.S. Pat. No. 5,667,767 for “Novel Compositions for Use in Embolizing Blood Vessels”, issued Sep. 16, 1997.
5
Greff, et al., U.S. Pat. No. 5,580,568 for “Cellulose Diacetate Compositions for Use in Embolizing Blood Vessels”, issued Dec. 3, 1996.
6
Kinugasa, et al., “Early Treatment of Subarachnoid Hemorrhage After Preventing Rerupture of an Aneurysm”,
J. Neurosurg
., 8:34-41 (1995)
7
Kinugasa, et al., “Prophylactic Thrombosis to Prevent New Bleeding and to Delay Aneurysm Surgery”
, Neurosurg
., 36:661 (1995)
8
Taki, et al., “Selection and Combination of Various Endovascular Techniques in the Treatment of Giant Aneurysms”,
J. Neurosurg
., 27:37-42 (1992)
9
Evans, et al., U.S. patent application Ser. No. 08/655,822 for “Novel Compositions for Use in Embolizing Blood Vessels”, filed May 31, 1996
10
Dunn, et al., U.S. Pat. No. 4,938,763 for “Biodegradable In-Situ Forming Implants and Methods of Producing Same”, issued Jul. 3, 1990
11
Greff, et al., U.S. Pat. No. 5,695,480 for “Novel Embolizing Compositions”, issued Dec. 9, 1997
12
Greff, et al., U.S. Pat. No. 5,830,178 for “Novel Methods for Embolizing Vascular Sites with an Embolizing Composition Comprising Dimethylsulfoxide, issued Nov. 3, 1998.
All of the above references are herein incorporated by reference in their entirety to the same extent as if each individual reference was specifically and individually indicated to be incorporated herein by reference in its entirety.
3. State of the Art
Embolization of blood vessels is conducted for a variety of purposes including the treatment of tumors, the treatment of lesions such as aneurysms, uncontrolled bleeding and the like.
Embolization of blood vessels is preferably accomplished via catheter techniques which permit the selective placement of the catheter at the vascular site to be embolized. In this regard, recent advancements in catheter technology as well as in angiography now permit neuroendovascular intervention including the treatment of otherwise inoperable lesions. Specifically, development of microcatheters and guide wires capable of providing access to vessels as small as 1 mm in diameter allows for the endovascular treatment of many lesions.
Embolizing compositions heretofore disclosed in the art include those comprising a biocompatible polymer, a biocompatible solvent and a contrast agent which allowed visualization of the in vivo delivery of the composition via fluoroscopy.
1-8
Such compositions typically contain no more than about 8 weight percent of biocompatible polymer based on the weight of the total composition.
Endovascular treatment regimens preferably include the use of a water insoluble, radiopaque contrast agent in the embolizing compositions in order that the physician can visualize delivery of the composition to the vascular site via conventional techniques such as fluoroscopy.
1-8
Additionally, the use of water insoluble contrast agents is beneficial during post treatment procedures to visualize the embolized mass during, for example, surgery or to monitor the disease condition and/or for retreatment purposes. Visualization is particularly necessary when using catheter delivery techniques in order to ensure both that the composition is being delivered to the intended vascular site and that the requisite amount of composition is delivered. The latter requirement is particularly critical in the treatment of aneurysms where only the aneurysm sac is intended to be filled while leaving the adjoining blood vessel unaffected. Accordingly, in such treatments, the amount of embolic composition delivered is selected to substantially fill but not overflow the aneurysm sac. If less than this amount of embolic composition is delivered to the aneurysm sac, the patient will be left with an active aneurysm which, in some cases, may grow or enlarge. If more than this amount of embolic composition is delivered, the composition will overflow into the adjoining blood vessel which can then embolize this blood vessel as well as the aneurysm. In the case where the affected blood vessel is in or leads to a critical body organ, e.g., the brain, permanent damage due to ischemia will result.
When delivered by catheter, the embolic compositions preferably comprise a biocompatible solvent, a biocompatible polymer and the water insoluble contrast agent. The biocompatible solvent is miscible or soluble in blood or other body fluid and also solubilizes the biocompatible polymer during delivery. The biocompatible polymer is selected to be soluble in the biocompatible solvent but insoluble in blood or other body fluid. The water insoluble contrast agent is suspended in the composition and, as above, permits the physician to fluoroscopically visualize catheter delivery of this composition. Upon contact with the blood or other body fluid, the biocompatible solvent dissipates from the embolic composition whereupon the biocompatible polymer precipitates in the presence of the water insoluble contrast agent and embolizes the blood vessel.
In practice, complications in this procedure have hindered the delivery of the embolic composition into vascular sites. For example, the use of a flow arresting device to limit blood flow during aneurysm treatment by injection of an embolic composition from a catheter has been heretofore suggested.
11
However, there are severe limitations placed on the use of such devices in combination with embolic compositions delivered via catheters. For example, in situ solidification of these composition is facilitated by blood transport of the biocompatible solvent away from the growing precipitate. However, a flow arresting device limits the amount of blood flow in the area adjacent the precipitate which, in turn, hinders further precipitate formation. Moreover, blood flow can be arrested for only a short period of time prior to the onset of tissue damage due to ischemia.
In addition, reproducible formation and control of precipitate formed from the embolic composition at the desired vascular site is critical to effectively treat vascular disorders. While techniques heretofore disclosed in the art provide an adequate level of reproducibility
12
, new methods which enhance the reproducibility of these techniques would be of great value.
In view of the above, the art is in search of improved embolization techniques.
SUMMARY OF THE INVENTION
This invention is directed to novel methods for embolizing blood vessels which are particularly suited for treating aneurysms, AVM's and high flow fistulas. These methods, either singularly or in combination, permit the facile delivery of liquid embolic compositions to vascular sites while overcoming one or more of the problems heretofore associated with vascular embolization by use of these compositions. These methods, either singularly or in combination, further permit the controlled, reproducible formation of an embolic precipitate at the vascular site.
In one aspect, the invention is directed to a method for embolizing a vascular site comprising an opening that is in communication with a vascular vessel by delivering via a catheter to said vascular site a com
Greff Richard J.
Hayman Douglas Ray
Moret Jacques
Roth Noah Michael
Tran Chinh Ngoc
Ghafoorian Roz
Hayes Michael J.
Micro Therapeutics Inc.
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