Apparatus comprising a drive cable for a medical device
An article comprising a drive cable suitable for high-speed operation in an anatomy having small-radii bends is disclosed. The drive cables disclosed herein include one or more physical adaptations that enable them to be “tuned” to avoid large amplitude vibrations during operation.
1. An article comprising a rotary drive cable, wherein the drive cable comprises:
(a) a first coil;
(b) at least a first physical adaptation comprising at least one additional coil;
(c) a second physical adaptation comprising at least one rod, wherein the rod is disposed between the first coil and the additional coil such that the coils and rod form a linear arrangement; and
(d) plurality of collars, wherein the collars couple each one of the coils to a respective rod.
2. The article of claim 1 wherein the first physical adaptation, which prevents harmonic resonance in the drive cable, is selected as a function of a forcing frequency.
3. The article of claim 2 wherein the forcing frequency is greater than 20,000 rpm.
4. The article of claim 2 wherein the forcing frequency is in a range of about 1000 rpm to about 100,000 rpm.
5. The article of claim 1 wherein the drive cable has three rods and two coils.
6. The article of claim 1 further comprising a sheath, wherein the drive cable is disposed in a lumen of the sheath.
7. The article of claim 1 wherein the article is a cardiac assist device.
8. The article of claim 7 wherein the cardiac assist device further comprises a motor and a pump assembly, and wherein the pump assembly comprises a rotatable element, and further wherein a first end of the drive cable is coupled to the motor and a second end of the drive cable is coupled to the pump assembly.
9. An article comprising a rotary drive cable, wherein the drive cable comprises:
(a) a first coil; and
(b) at least a first physical adaptation that affects a dynamic response of the drive cable, wherein the first physical adaptation is selected as a function of a forcing frequency to prevent harmonic resonance in the drive cable, and wherein the first physical adaptation comprises at least one collar, wherein the collar is disposed on the first coil and is not used as a coupling.
10. The article of claim 9 wherein the forcing frequency is greater than 20,000 rpm.
11. The article of claim 9 wherein the forcing frequency is in a range of about 1000 rpm to about 100,000 rpm.
12. The article of claim 9 wherein the first physical adaptation further comprises at least one additional coil, wherein the additional coil and the first coil are linearly coupled.
13. The article of claim 12 further comprising a second physical adaptation, wherein the second physical adaptation comprises a second collar, wherein the second collar couples the first coil and the at least one additional coil to each other.
14. The article of claim 12 further comprising a second physical adaptation, wherein the second physical adaptation comprises at least one rod, wherein the rod is disposed between the first coil and the additional coil such that the coils and rod form a linear arrangement.
15. The article of claim 9 wherein there is a plurality of collars disposed on the first coil.
16. The article of claim 15 wherein at least one of the collars differs from the other of the collars in terms of at least one characteristic selected from the group consisting of length, diameter, stiffness, and mass.
17. The article of claim 12 wherein the first physical adaptation further comprises at least one bound section of the at least one additional coil.
18. The article of claim 9 further comprising a sheath, wherein the drive cable is disposed in a lumen of the sheath.
19. The article of claim 9 wherein the article is a cardiac assist device.
20. The article of claim 19 wherein the cardiac assist device further comprises a motor and a pump assembly, and wherein the pump assembly comprises a rotatable element, and further wherein a first end of the drive cable is coupled to the motor and a second end of the drive cable is coupled to the pump assembly.
21. The article of claim 9 wherein the first coil comprises an encapsulating material.
22. An article comprising a rotary drive cable, wherein the drive cable comprises:
(a) a first coil, wherein the first coil is a machined coil; and
(b) at least a first physical adaptation that affects a dynamic response of the drive cable, wherein the first physical adaptation is selected as a function of a forcing frequency to prevent harmonic resonance in the drive cable, wherein the first physical adaptation comprises a variation in size of a material that forms the first coil.
23. The article of claim 22 wherein the forcing frequency is greater than 20,000 rpm.
24. The article of claim 22 wherein the forcing frequency is in a range of about 1000 rpm to about 100,000 rpm.
25. The article of claim 22 wherein the dynamic response that is affected by the first physical adaptation is a vibrational characteristic of the drive cable.
26. The article of claim 22 and further wherein the first physical adaptation affects a characteristic of the drive cable, wherein the characteristic is selected from the group consisting of drive-cable tension, localized drive-cable bending stiffness, and localized drive-cable linear density.
27. The article of claim 22 further comprising a sheath, wherein the drive cable is disposed in a lumen of the sheath.
28. The article of claim 22 wherein the article is a cardiac-assist device.
29. The article of claim 28 wherein the cardiac assist device further comprises a motor and a pump assembly, and wherein the pump assembly comprises a rotatable element, and further wherein a first end of the drive cable is coupled to the motor and a second end of the drive cable is coupled to the pump assembly.