Surgery – Instruments – Blood vessel – duct or teat cutter – scrapper or abrader
Patent
1997-09-29
1999-03-02
Buiz, Michael
Surgery
Instruments
Blood vessel, duct or teat cutter, scrapper or abrader
604 22, A61B 1722
Patent
active
058764143
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a catheter of the type known as a rotary catheter.
A catheter of this kind is used in particular for treating occlusive diseases of the arteries by dislodging stenoses and breaking up blood clots. It is introduced into the artery and is advanced as far as the stenosed area which is to be treated. A cutting tool which can be driven in rotation is arranged at its front or leading end.
DISCUSSION OF THE BACKGROUND
A known catheter, for example the one from EP-B1-0,267,539, has as its cutting tool a substantially elliptical milling cutter which is provided with abrasive material on its surface and is driven at a speed of up to 160,000 rpm. The milling cutter is connected via a flexible drive shaft to a rotary drive mechanism which is arranged at the other end of the catheter. The drive shaft runs inside a tubular sheath which serves as a catheter tube. A guide wire extending right through the drive shaft is introduced into the artery before introduction of the catheter and is advanced right through the stenosis.
In this known rotary catheter, the particles which are dislodged by the milling cutter are not removed from the body, since they should normally be smaller than the red blood cells by about 7 m. If, however, some of 30 the particles which have been dislodged are larger than red blood cells, then there is a considerable risk of their blocking the bloodstream at another location and thereby causing an embolism.
From the literature, it is also known for the particles which have been dislodged to be drawn off through the catheter by suction. Here, however, there is the risk that too many particles will fail to be caught and that these will thus pass into the bloodstream.
The invention is therefore based on the object of providing a catheter which is of the type mentioned at the outset and in which the particles which have been dislodged are removed from the circulation almost in their entirety.
According to the invention, these and other objects are accomplished by providing a catheter comprised of a tubular sheath, a cutting tool provided at a front end of the sheath and the flexible drive shaft provided within the sheath which connects the cutting tool with the rotary drive mechanism. The flexible drive shaft is formed with a helical shape such that it conveys dislodged deposits recovered by the cutting tool axially along the length of the tubular sheath. By providing the catheter with a helically shaped drive shaft provided within a tubular sheath, the catheter according to the present invention ensures an immediate and continuous withdrawal of the dislodged or detached particles, so as to reliably prevent these particles from passing into the circulation of the bloodstream.
In one embodiment of the invention, the flexible drive shaft can be constructed of a helically wound wire, which is a particularly convenient form for the drive shaft to be constructed of.
The flexible drive shaft of the above embodiment can optionally be constructed of a helically wound wire that has a substantially rectangular cross section. By using a wire with a substantially rectangular cross section, the resulting helically wound flexible drive shaft with a higher surface area and therefore a higher conveying capacity since the surface area of a square cross section is greater than that of, for example, a round wire cross section.
The flexible drive shaft of the above embodiment can also, optionally, be coated thereby making it possible, on the one hand, to choose freely a material which is particularly suitable as to strength, and, on the other hand, to provide an appropriate protection against corrosion and satisfy corresponding requirements in respective hygiene and tribiology.
According to a further embodiment of the present invention, a cutting tool can be provided with a slot through which detached deposits are passed into the cutting tool, and the flexible drive shaft can be extended into the inside of the cutting tool. By providing the flexible drive shaft as suc
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Buiz Michael
Straub Medical AG
Truong Kevin
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