SPECIFICATIONCathetersThis invention relates to an intravenous coagulationcatheter.
An object of the invention is to provide such a catheterwhich is adapted to form firm blood coagulations within the venous or arterial system of a patient by utilising diathermy pulses between two electrodes at a distal end of the catheter. The distal end ofthe catheter is the end which is inserted into a patient.
According to the present invention, a coagulation catheter comprises an outer main shaft, and an inner shaft assembly which is slidable inside the main shaft and includes a central electrode, an insulation sleeve surrounding the central electrode and a conductive wire braiding surrounding the insulation sleeve; meansformoving the inner shaft assembly with in the mainshaftsothatthe distal end of the inner shaft assemblycan be made to protrude from the distal end ofthemainshaftortobewithdrawn into the main shaftasdesired; and means atthe proximal end of the inner shaft assembly to permitthe assemblyto be connectedtoadiathermy or like apparatus.The cathetermaybea balloon catheterinwhich case an inflatable balloon surroundsthe main shaft nearthe distal endthereofand an inflation lumen extends through the main shaftfromthe proximal end of the catheterto an opening or openings with in the balloon.
lfthecatheterisaballooncatheter, means are provided atthe proximal endto enable the catheterto be connected to a syringe or other inflating means.
In one embodimentof the invention, a plurality of electrically conductive spring fingers may be fixed to the innershaftassembly at its distal end, these fingers being arranged to spring outwards when the distal end oftheinnershaft assembly protrudes from the distal endofthe main shaftandto collapse onto the innershaftassemblywhen the distal end of the said assembly is withdrawn into the main shaft.
An application of the invention to a balloon catheter is illustrated schematically in the accompanying drawings in which:Figure 1 illustrates a balloon catheter according to the invention;Figure 2 is a fragmentary longitudinal section of part ofthecatheter; andFigure 3 is a cross-section through the catheter.
In the illustrated embodiment of the invention, an intravenous coagulation balloon catheter comprises an inner shaft assembly which includes an inner central electrode 1. One end of the catheter is insertable in a patient and this end is called the distal end. This electrode is an electrically conductive rod, for example of copper having either a stainless steel sleeve atthe distal end or a copper sleeve coated with silver. The electrode 1 is a snug fit in an insulation sleeve or inner shaft 2 which is a tube extruded from a suitable plastic material, e.g. nylon. The inner shaft 2 is surrounded bya braiding 3 preferablyofstainless steel wire. This assembly is a sliding fit in an outer tube or main shaft 4which is also of plastics material, such as nylon or polyvinyl chloride.
Nearthe distal endofthecatheteris an inflatableballoon 5 (Figure 1 ) which may be of conventional construction. An inflation passage or lumen 6, called an inflation lumen, runs through the wall of the main shaft4 and opens where the shaft is covered bytheballoon. Fluid can be passed from an inlet 7, whichmay be a luerfitting arranged to receive a syringe, in amount 8 atthe proximal end of the main shaft 4 therebyto inflate the balloon.
In the embodiment illustrated in the drawings, spring feelers orfingers 9 are provided atthe distal end of the inner shaft assembly. These feelers are not essential to the present invention. They are preferably made of gold alloy but may be of beryllium copper which is silver plated or any other suitable non-toxic electro conductive material. These fingers are electricalls and mechanically connected to the braid 3 and are insulated from the central electrode. These feelers 9 can be opened as shown in Figure 1 or collapsed onto the inner shaft assembly.
The innershaftassembly is, as previouslystated, movable in the main shaft 4. When the inner assembly protrudes from the distal end of the main shaft, the feelers 9 spring open as shown. Finger grips 10 extend from the mount 8 which is secured to the main shaft. A slider member 11 is fixed to the inner assembly and is movable into and out of the mount 8 against the action of an internal spring (not shown). When the slider member 11 is fully positioned inside the mount 8, it may be automatically locked in position and in that position the distal end of the inner shaft assembly protrudes from the distal end of the main shaft as shown in Figure 1. If a locking mechanism is provided, it may be released to permit the slider member 11 to be withdrawn from the mount in which case the distal end ofthe inner shaft assembly is withdrawn into the main shaft.
The slider member 11 is electrically connected with the innershaft assembly and has a plug 12 which enables itto be connected to a surgical diathermy apparatus.