Devices and methods for low pressure tumor embolization

1. A method of transarterial embolization agent delivery at a low pressure, the method comprising:

advancing a delivery device with an occlusion structure in a retracted non-occlusive configuration, through a supply artery having a plurality of collateral vessels that branch therefrom and being in fluid communication with a target anatomical structure, to a vascular position in the supply artery that is in the vicinity of the target anatomical structure, the target structure having terminal capillary beds;

expanding the occlusion structure from the retracted non-occlusive configuration to an expanded occlusive configuration;

lowering a mean arterial pressure in a vascular space distal to the expanded occlusion structure;

redirecting fluid flow from the collateral vessels toward the lowered pressure vascular space and into the target anatomical structure such that a fluid flow direction is reversed in at least some of the collateral vessels;

injecting an embolization agent through the delivery device and into the lowered pressure vascular space; and

delivering the embolization agent from the lowered pressure vascular space into the target anatomical structure.

2. A method according to claim 1 , wherein the mean arterial pressure in the lowered pressure vascular space is lowered during the lowering step to between 10% and 60% of a normal mean arterial pressure.

3. A method according to claim 1 , wherein the lowering step comprises measuring a pressure in the vascular space after expanding the occlusion structure.

4. A method according to claim 3 , wherein the lowering step further comprises ensuring the measured pressure is within a predetermined range before proceeding with the injecting step.

5. A method according to claim 1 , wherein the lowering step comprises waiting a predetermined period of time before proceeding with the injecting step to ensure that a sufficient pressure drop has occurred.

6. A method according to claim 1 , wherein the fluid is predominantly blood.

7. A method according to claim 1 , wherein the fluid is predominantly interstitial fluid.

8. A method according to claim 1 , wherein the embolization agent is injected with a flow rate in the range of 0.25 to 10 ml/minute.

9. A method according to claim 1 , wherein the delivery device comprises a catheter.

10. A method according to claim 1 , wherein the delivery device comprises a needle.

11. A method according to claim 1 , wherein the delivery device comprises a cannula.

12. A method according to claim 1 , wherein the occlusion structure allows a fluid flow of 5 to 25% of normal to bypass the occlusion structure after it has been expanded into the occlusive configuration.

13. A method according to claim 1 , wherein the occlusion structure creates a substantially full occlusion having less than 2% bypass blood flow.

14. A method according to claim 1 , wherein the occlusion structure comprises a balloon.

15. A method according to claim 14 , wherein the balloon is provided with a generally v-shaped channel extending along a least a portion of its length, thereby providing a fluid bypass channel when the balloon is inflated.

16. A method according to claim 14 , wherein the balloon is provided with a spiral channel extending from a proximal end of the balloon to a distal end, thereby providing a fluid bypass channel when the balloon is inflated.

17. A method according to claim 1 , wherein the delivery device is provided with a pressure transducer located distal to the occlusion structure and configured to sense fluid pressure when located in the supply artery.

18. A method according to claim 1 , wherein the target anatomical structure is a tumor.

19. A method according to claim 1 , wherein the target anatomical structure is a prostate.

20. A method according to claim 1 , wherein the target anatomical structure is a uterus.

21. The method of claim 1 , further comprising maintaining antegrade flow in at least one vessel in the lowered pressure vascular space.