High viscosity embolizing compositions

1. A method for enhancing the formation of a solid, non-migratory coherent mass at a selected vascular site of a mammal which method comprises:

(a) placing a delivery device having an ejection port at a selected vascular site in a mammal;

(b) delivering through the ejection port of the delivery device a composition capable of embolizing an aneurysm at a vascular site comprising:

a. a biocompatible polymer at a concentration of from about 12 to about 50 weight percent based on the total weight of the composition;

b. a biocompatible contrast agent wherein a sufficient amount of said contrast agent is employed in said composition to effect visualization in vivo; and

c. a biocompatible solvent which solubilizes said biocompatible polymer;

wherein sufficient amounts of said polymer are employed in said composition such that upon delivery to said vascular site a polymer precipitate forms which embolizes said vascular site;

and further wherein the biocompatible polymer has a molecular weight and/or concentration sufficient to impart to the composition a viscosity of at least about 150 cSt at 40° C.

2. A method for enhancing the formation of a solid, non-migratory coherent mass at a selected vascular site of a mammal which method comprises:

(a) placing a delivery device having an ejection port at a selected vascular site in a mammal;

(b) delivering through the ejection port of the delivery device a composition capable of embolizing an aneurysm at a vascular site comprising:

a) a biocompatible polymer at a concentration of from about 12 to about 50 weight percent;

b) a biocompatible contrast agent at a concentration of from about 10 to about 40 weight percent; and

c) a biocompatible solvent from about 10 to 88 weight percent;

wherein the weight percents of the biocompatible polymer, contrast agent, and biocompatible solvent are based on the total weight of the composition;

and further wherein the biocompatible polymer has a molecular weight and/or concentration sufficient to impart to the composition a viscosity of at least about 150 cSt at 40° C.

3. The method according to claim 1 or claim 2 wherein, prior to (b) above, a blood flow attenuation device is inserted immediately upstream the ejection port of said catheter.

4. The method according to claim 3 wherein, said blood flow attenuation device is an inflatable microballoon which permits both normal and attenuated blood flow depending upon whether the microballoon is deflated or inflated.

5. The method according to claim 1 or claim 2 wherein said composition has a viscosity of at least about 200 cSt at 40 0° C.

6. The method according to claim 5 wherein said composition has a viscosity of at least about 500 cSt at 40° C.

7. The method according to claim 6 wherein said composition has a viscosity of from about 500 to 5,000 cSt at 40° C.

8. The method according to claim 1 or claim 2 wherein said composition has a migration distance from the point of injection of less than 25 mm.

9. The method according to claim 1 or claim 2 wherein said biocompatible solvent is selected from the group consisting of ethyl lactate, dimethylsulfoxide, ethanol and acetone.

10. The method according to claim 9 wherein said biocompatible solvent is dimethylsulfoxide.

11. The method according to claim 1 or claim 2 wherein said contrast agent is a water insoluble contrast agent.

12. The method according to claim 11 wherein said water insoluble contrast agent is selected from the group consisting of tantalum, tantalum oxide, tungsten and barium sulfate.

13. The method according to claim 12 wherein said contrast agent is tantalum.

14. The method according to claim 1 or claim 2 wherein said contrast agent is a water soluble contrast agent.

15. The method according to claim 1 or claim 2 wherein said biocompatible polymer is a non-biodegradable, biocompatible polymer.

16. The method according to claim 15 wherein said non-biodegradable, biocompatible polymer is selected from the group consisting of cellulose acetates, ethylene vinyl alcohol copolymers, hydrogels, polyacrylonitrile, polyvinylacetate, cellulose acetate butyrate, nitrocellulose, copolymers of urethane/carbonate, copolymers of styrene/maleic acid, and mixtures thereof.

17. The method according to claim 16 wherein said biocompatible polymer is an ethylene and vinyl alcohol copolymer.

18. The method according to claim 1 or claim 2 wherein said biocompatible polymer is a biodegradable, biocompatible polymer.