Methods and systems for the inhibition of vascular hyperplasia
First Claim
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1. A method for inhibiting neointimal hyperplasia in an artery, said method comprising:
- exposing a target site at risk of neointimal hyperplasia within the artery to vibrational energy at a mechanical index and for a time sufficient to inhibit said intimal hyperplasia, wherein the vibrational energy comprises pressure waves which travel to the arterial wall in a substantially radial direction.
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Abstract
Post-interventional neointimal hyperplasia in arteries is treated by the application of ultrasonic energy. Usually, an intravascular catheter having an interface surface is positioned at a target site in the artery which has previously been treated. The interface surface is vibrationally excited to apply energy to the arterial wall in a manner which inhibits smooth muscle cell proliferation in the neointimal layer.
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Citations
19 Claims
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1. A method for inhibiting neointimal hyperplasia in an artery, said method comprising:
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exposing a target site at risk of neointimal hyperplasia within the artery to vibrational energy at a mechanical index and for a time sufficient to inhibit said intimal hyperplasia, wherein the vibrational energy comprises pressure waves which travel to the arterial wall in a substantially radial direction. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
intravascularly introducing an interface surface to the target site within the artery; and
ultrasonically driving the interface surface to vibrate the interface surface in a radial direction and radiate ultrasonic energy into the arterial wall adjacent the target site.
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4. A method as in claim 3, wherein the introducing step comprises:
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providing a flexible catheter having at least one ultrasonic transducer disposed near its distal end;
energizing the ultrasonic transducer, wherein the transducer drives the interface surface.
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5. A method as in claim 4, wherein the interface surface directly contacts the arterial wall at the target site.
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6. A method as in claim 4, wherein the interface surface is spaced-apart from the arterial wall, wherein the ultrasonic energy is transmitted through a liquid medium disposed between the interface surface and the arterial wall.
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7. A method as in claim 6, wherein the liquid medium is entrapped within a balloon which is inflated against the arterial wall.
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8. A method as in any of claims 1-7, wherein the vibrational energy does not cause significant cavitation.
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9. A method as in any of claims 1-7, wherein the vibrational energy causes a temperature rise below 10°
- C. in the wall of the artery.
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10. A method as in any of claims 1-7, wherein the vascular smooth muscle cells at least mostly remain viable but in a quiescent state in the neointimal layer after exposure to the vibrational energy.
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11. A method as in any of claims 1-7, wherein migration of vascular smooth muscle cells into the neointimal layer is not substantially inhibited.
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12. A method as in any of claims 1-7, wherein viability of vascular smooth muscle cells in a medial layer of the artery is not significantly inhibited.
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13. A method as in any of claims 1-7, wherein vascular smooth muscle cell proliferation in the neointimal layer exposed to vibrational energy is inhibited by at least 2% after seven days in comparison to such proliferation in a neointimal layer not exposed to the vibrational energy.
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14. A method as in any of claims 1-7, wherein the area of the neointimal layer exposed to vibrational energy is inhibited by at least 10% after 28 days in comparison to the area of a neointimal layer not exposed to the vibrational energy.
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15. A method as in any of claims 1-7, wherein the vibrational energy has a frequency in the range from 100 kHz to 5 MHz.
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16. A method as in claim 15, wherein the intensity is in the range from 0.01 W/cm2 to 100 W/cm2.
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17. A method as in claim 16, wherein the frequency and intensity are selected to produce a mechanical index at the neointimal wall in the range from 0.1 to 50.
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18. A method as in any of claims 1-7, wherein the vibrational energy is directed against the arterial wall with a pulse repetition frequency (PRF) in the range from 10 Hz to 10 kHz.
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19. A method as in any of claims 1-7, wherein the energy is directed against the arterial wall with a duty cycle in the range from 0.1 to 100 percent.
Specification