Photoacoustic removal of occlusions from blood vessels
First Claim
1. A method of opening to the flow of blood a human cerebral blood vessel that is blocked by a clot, comprising:
- positioning within said cerebral vessel an array of optical fiber ends adjacent to and extending in a direction across a surface of the clot, said optical fibers individually having a core diameter less than 100 microns, directing a sequence of one or more pulses of radiation along one of the plurality of optical fibers and out of its end and then repeating directing such a sequence of pulses along individual ones of others of said plurality of optical fibers at a time, said pulses individually containing less than 250 micro-Joules of energy and having a duration less than 100 nanoseconds in order to generate a shock wave followed by a bubble which together cause a portion of the clot to be emulsified, introducing a flow of liquid into the vessel adjacent the surface of the clot while radiation is being directed out of said optical fibers, and while so directing the radiation pulses and the liquid, advancing the catheter end through the clot as the clot becomes emulsified until the blockage to the flow of blood through the vessel is removed.
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Accused Products
Abstract
Partial or total occlusions of fluid passages within the human body are removed by positioning an array of optical fibers in the passage and directing treatment radiation pulses along the fibers, one at a time, to generate a shock wave and hydrodynamic flows that strike and emulsify the occlusions. A preferred application is the removal of blood clots (thrombi and emboli) from small cerebral vessels to reverse the effects of an ischemic stroke. The operating parameters and techniques are chosen to minimize the amount of heating of the fragile cerebral vessel walls occurring during this photoacoustic treatment. One such technique is the optical monitoring of the existence of hydrodynamic flow generating vapor bubbles when they are expected to occur and stopping the heat generating pulses propagated along an optical fiber that is not generating such bubbles.
192 Citations
26 Claims
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1. A method of opening to the flow of blood a human cerebral blood vessel that is blocked by a clot, comprising:
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positioning within said cerebral vessel an array of optical fiber ends adjacent to and extending in a direction across a surface of the clot, said optical fibers individually having a core diameter less than 100 microns, directing a sequence of one or more pulses of radiation along one of the plurality of optical fibers and out of its end and then repeating directing such a sequence of pulses along individual ones of others of said plurality of optical fibers at a time, said pulses individually containing less than 250 micro-Joules of energy and having a duration less than 100 nanoseconds in order to generate a shock wave followed by a bubble which together cause a portion of the clot to be emulsified, introducing a flow of liquid into the vessel adjacent the surface of the clot while radiation is being directed out of said optical fibers, and while so directing the radiation pulses and the liquid, advancing the catheter end through the clot as the clot becomes emulsified until the blockage to the flow of blood through the vessel is removed. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A method of opening to the flow of blood human cerebral blood vessel that is blocked by a clot, comprising:
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directing electromagnetic radiation through optical fiber transmission media within the cerebral vessel toward said clot at different locations across the clot in time sequence, simultaneously directing a cooling liquid within the cerebral vessel in the vicinity of the clot, and maintaining an average power level of the radiation directed within the cerebral vessel at less that one-half of one watt. - View Dependent Claims (20, 21, 22)
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23. A method of opening to the flow of blood a human cerebral blood vessel that is blocked by a clot, comprising:
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positioning an end of a catheter into a blood vessel of the human a distance from the cerebral blood vessel and advancing the catheter end at least 75 centimeters through various human vessels to within the cerebral vessel in a manner to position an open end of a lumen and ends of a plurality of optical fibers directed toward or imbedded in the clot, said optical fibers individually having a core diameter within a range of from 20 to 100 microns, directing radiation along the plurality of optical fibers, one at a time in sequence, against the clot while a liquid is being discharged at a rate within a range of one tenth to five cubic centimeters per minute into the vessel through said lumen open end, said radiation being directed along each of the plurality of fibers in the form of a plurality of pulses with a repetition rate within a range of from 1 to 20 kilo-Hertz, an amount of energy per pulse within a range of from 10 to 250 micro-Joules, and a duration of the individual pulses within a range of from 1 to 100 nanoseconds, in a manner that the pulses individually generate a shock wave followed by a bubble that together cause a portion of the clot to be emulsified and the average power delivered within the cerebral vessel is less than one-half of one watt, and advancing the catheter end through the clot as the clot becomes emulsified until the blockage to the flow of blood through the vessel is removed.
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24. A system for the removal of a clot from a blood vessel, comprising:
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a catheter having a length in excess of 75 centimeters between first and second ends thereof and an outside diameter less than one-half of one millimeter alone at least a portion of the length adjacent the first end, said catheter including a plurality of optical fibers that individually have a core diameter less than 100 microns and a lumen extending along said length, said optical fibers terminating in a spatial array across a first end of the catheter, a source of liquid connected to supply cooling liquid to the lumen at the second end of the catheter, the lumen having an inside diameter and the source having a capacity such that the liquid is discharged from the lumen at the first end of the catheter with a rate of flow within a range of from one-tenth to five cubic centimeters per minute, and a source of electromagnetic radiation connected to the optical fibers at the second end of the catheter in a manner to direct individual pulses of said radiation along the optical fibers, one at a time in sequence, with the pulses individually having a duration within a range of from one to 100 nanoseconds and containing an amount of energy within a range of from 10 to 250 micro-Joules of energy, and with a maximum average power of less than one-half of one watt being delivered from the optical fibers at the first end of the catheter. - View Dependent Claims (25, 26)
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Specification