Apparatus comprising a drive cable for a medical device (II)
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 system-specific rotary drive cable that, in operation, is rotated at a rate of at least 1000 rpm to drive a rotatable element of the article, wherein the rotary drive cable is designed for use in a system that includes a first section and a second section through which at least a portion of the rotary drive cable must traverse to position the rotatable element in an operational location in the system, wherein the first section of the system is relatively straight compared to the second section of the system, and the second section is relatively bent compared to the first section, and further wherein:
(a) the drive cable comprises a plurality of discrete segments that are coupled end to end;
(b) the plurality of segments comprises a first rod and a first coil;
(c) a first location of the first rod and a second location of the first coil along the drive cable are a function of:
(i) a distance between the first section and the second section of the system; and
(ii) a distance between the second section of the system and the operational location, so that when the rotatable element is in the operational position in the system, the first rod is within the first section of the system and the first coil is in the second section of the system.
2. The article of claim 1 wherein the plurality of segments further includes a second rod, a third rod, and a second coil, and wherein the segments are arranged serially along the drive cable as follows: first rod, first coil, second rod, second coil, third rod.
3. The article of claim 2 wherein a length of the first rod is with a range of about 5 centimeters to about 25 centimeters.
4. The article of claim 2 wherein a length of the first coil is with a range of about 10 centimeters to about 90 centimeters.
5. The article of claim 2 wherein a length of the second rod is with a range of about 10 centimeters to about 90 centimeters.
6. The article of claim 2 wherein a length of the second coil is with a range of about 5 centimeters to about 25 centimeters.
7. The article of claim 2 wherein a length of the third rod is with a range of about 5 centimeters to about 15 centimeters.
8. The article of claim 1 further comprising a motor, wherein a first end of the drive cable is operatively coupled to the motor.
9. The article of claim 1 further comprising an impeller, wherein a second end of the drive cable is operatively coupled to the impeller.
10. An article comprising a system-specific rotary drive cable that is rotated at a rate of at least 1000 rpm to drive a rotatable element of the article, wherein the drive cable comprises a plurality of segments disposed in a linear arrangement, wherein:
(a) the segments comprise one or more segments of a first type and one or more segments of a second type;
(b) segments of the first type possess a relatively greater capacity for transmitting torque along a curved path than segments of the second type;
(c) a position of the segments in the linear arrangement thereof is selected to correspond to a geometry of a system in which the drive cable is used, wherein segments of the first type are positioned to coincide with relatively more curved regions of the system and segments of the second type are positioned to coincide with relatively less curved regions of the system when the rotatable element is at an operational location in the system.
11. The article of claim 10 wherein the segments of the first type comprise a coil.
12. The article of claim 10 wherein the segments of the first type have a different structural configuration than the segments of the second type.
13. The article of claim 10 wherein in the linear arrangement, the segments of the first type alternate with segments of the second type.
14. The article of claim 10 further comprising a motor, wherein a first end of the drive cable is operatively coupled to the motor.
15. The article of claim 10 further comprising an impeller, wherein a second end of the drive cable is operatively coupled to the impeller.