Medical device with means to improve transmission of torque along a rotational drive shaft
The present invention provides minimally invasive imaging probe/medical device having a frictional element integrated therewith for reducing non-uniform rotational distortion near the distal end of a medical device, such as an imaging probe which undergoes rotational movement during scanning of surrounding tissue in bodily lumens and cavities.
1. A catheter device for insertion into bodily lumens or cavities, comprising:
an elongate hollow sheath having a distal end portion, a proximal end portion, and an elongate midsection;
a rotational drive shaft housed within said elongate hollow sheath;
a functional element mounted to said rotational drive shaft at a location that is remote from said proximal end portion of said elongate hollow sheath; and
at least one frictional component operatively associated with at least one of said rotational drive shaft and said functional element, such that said frictional component bears radially outwards to be in frictional contact with an inner surface of said elongate hollow sheath;
said frictional component being configured such that an amount of frictional force produced by contact between said frictional component and said inner surface of said elongate hollow sheath is uniform regardless of the angular orientation and longitudinal translation of the rotating components within said hollow elongate sheath;
said frictional component being configured such that the contact between said frictional component and said inner surface of said elongate hollow sheath is independent of the angular orientation and longitudinal translation of the rotating components within said hollow elongate sheath; and
such that during rotation of said functional element by said rotational drive shaft, said rotational drive shaft is configured to operate with a higher torsional load than in an absence of said frictional component, thereby reducing non-uniform rotational distortion as said functional element rotates inside said elongate hollow sheath.
2. The catheter device according to claim 1 wherein said at least one frictional component comprises one or more generally cylindrical frictional components circumferentially enveloping a portion of said rotational drive shaft, said generally cylindrical frictional components having a radially outwardly projecting portion which bears against the inner surface of said elongate hollow sheath.
3. The catheter device according to claim 2 wherein said at least one generally cylindrical frictional component comprises a plurality of such components spaced along a length of said rotational drive shaft.
4. The catheter device according to claim 2 wherein said at least one generally cylindrical frictional component comprises one or more cylindrical members having an inner radius approximately equal to an outer radius of the rotational drive shaft, and has an outer radius approximately equal to an inner radius of the elongate hollow sheath.
5. The catheter device according to claim 2 wherein said at least one frictional component comprises one or more cylindrical members having an inner radius approximately equal to an outer radius of the rotational drive shaft, wherein the one or more cylindrical members have an outer circumference shaped for making multiple contacts around its circumference between the one or more frictional components and the inner surface of the elongate hollow sheath.
6. The catheter device according to claim 2 wherein said at least one cylindrical frictional component comprises one or more cylindrical members having an inner radius approximately equal to an outer radius of the rotational drive shaft, wherein the cylindrical members comprise one or more flexible extensions radiating therefrom.
7. The catheter device according to claim 1 wherein said at least one frictional component comprises one or more generally cylindrical frictional components that circumferentially envelops said functional element, wherein said generally cylindrical frictional components have a portion that extends radially from said functional element and bears against the inner surface of said elongate hollow sheath.
8. The catheter device according to claim 7 wherein said one or more generally cylindrical frictional components comprise a plurality of such components spaced along said functional element.
9. The catheter device according to claim 7 wherein said one or more generally cylindrical frictional components comprise one or more cylinders having an inner radius approximately equal to an outer radius of the functional element, and has an outer radius approximately equal to an inner radius of the elongate hollow sheath.
10. The catheter device according to claim 7 wherein said one or more cylindrical frictional components comprise one or more cylinders having an inner radius approximately equal to an outer radius of the functional element, wherein the frictional component has an outer circumference shaped for making multiple contacts around its circumference between each frictional component and the inner surface of the elongate hollow sheath.
11. The catheter device according to claim 7 wherein said one or more cylindrical frictional components are one or more cylindrical members having an inner radius approximately equal to an outer radius of the functional element, wherein the one or more cylindrical frictional components comprise one or more flexible extensions radiating therefrom, each flexible extension having a relatively large surface contact with the inner surface of the elongate hollow sheath.
12. The catheter device according to claim 1 wherein said at least one frictional component is a generally spherically shaped and flexible component circumferentially enveloping a portion of said rotational drive shaft, having a radius such that an outer circumference of said spherically shaped component radially bears against the inner surface of said elongate hollow sheath.
13. The catheter device according to claim 1 wherein said at least one frictional component comprises a soft or compressible material so that as fluid is flushed in a proximal to distal direction through the lumen of the hollow elongate sheath, walls of the one or more frictional components can temporarily release their contact with the inner surface of the sheath, thus allowing fluid to flow through the lumen and exit from a distal end portion of the elongate hollow sheath.
14. The catheter device according to claim 13 including fenestrations built into walls of the frictional component to assist fluid passage past the frictional component.
15. The catheter device according to claim 1 wherein said functional element is generally cylindrical in shape, and wherein said frictional component is a generally spherically shaped member circumferentially enveloping said functional element, having a radius such that an outer circumference of said spherically shaped component radially bears against the inner surface of said elongate hollow sheath.
16. The catheter device according to claim 1 wherein said functional element is an imaging assembly configured for emitting an energy beam and receiving reflected energy signals.
17. The catheter device according to claim 1 wherein said functional element is selected from the group consisting of minimally invasive imaging probes, atherectomy devices, steering probes, energy-delivery devices for localized delivery of radiation, radiofrequency ablation, thermal energy, cooling probes, therapeutic ultrasound or light energy and minimally invasive surgical devices.
18. The catheter device according to claim 3 wherein said plurality of components spaced along said length of said rotational drive shaft are sufficient to damp vibrations of said functional element and said rotational drive shaft.
19. The catheter device according to claim 1 wherein said frictional component is configured to permit fluid flow between regions distal and proximal thereto while said frictional component is in contact with said inner surface of said elongate hollow sheath.
20. The catheter device according to claim 19 wherein said frictional component is further configured to permit fluid flow unidirectionally.
21. The catheter device according to claim 1 wherein the frictional force resulting from the frictional contact is effectively uniform at a given angular velocity.
22. The catheter device according to claim 1 wherein said frictional component is remote from the proximal end of the rotational drive shaft.
23. The catheter device according to claim 1 wherein the frictional component is proximate to the functional element.