US 3794041 A
A gastrointestinal catheter of elongated shape, flexible and including ferromagnetic material enabling it, when inserted into the cavity of a body part, to be attracted by a magnet external of the body in order to manipulate the body part with the catheter. In the described embodiments, the ferromagnetic material is in the form of beads enclosed within a tube of inert resilient material, or strung on a string and coated with inert material.
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United States Patent [191 Frei et a1.
[ Feb. 26, 1974 GASTROINTESTINAL CATHETER  Inventors: Ephraim H. Frei; Shmuel Yerushalmi, both of Rehovot, Israel  Assignee: Yeda Research and Development Co.
Ltd., Rehovot, Israel 22 Filed: Nov. 30, 1971 21 App]. No.: 203,138
 US. Cl. 128/348, l28/l.3, 128/2 M  Int. Cl A6lm 25/00  Field of Search. 128/2 M, 205 R, 1.3, 1.4, 4-6, 128/7, 8, 303 R, 348, 349 R, 350 R, 356;
 References Cited UNITED STATES PATENTS 3,674,014 7/1972 Tillander 128/348 X 3,043,309 7/1962 McCarthy 128/348 2,863,458 12/1958 Modny et al 128/303 R 3,206,657 9/1965 Moriya 335/303 FOREIGN PATENTS OR APPLICATIONS 1,261,276 2/1968 Germany 128/6 OTHER PUBLICATIONS Frei et al., Med. Res. Engr. Fourth Quar. 1966, pp. 1 l-l 8 Primary Examiner-Dalton L. Truluck  ABSTRACT A gastrointestinal catheter of elongated shape, flexible and including ferromagnetic material enabling it, when inserted into the cavity of a body part, to be attracted by a magnet external of the body in order to manipulate the body part with the catheter. In the described embodiments, the ferromagnetic material is in the form of beads enclosed within a tube of inert resilient material, or strung on a string and coated with inert material.
2 Claims, 3 Drawing Figures GASTROINTESTINAL CATHETER BACKGROUND OF THE INVENTION The present invention relates to catheters insertable into a body cavity, and particularly to gastrointestinal catheters for insertion into a part of the intestinal tract, such as the intestines.
In certain types of disease, the only effective treatment consists of massive irradiation of the afflicted organ. This applies to many cases of carcinoma of the cervix, of the bladder, of the ovary and of the uterus, and also in similar diseases. One of the most serious problems of such treatment is the high sensitivity of the intestines to radiation damage, which seems to be due to the continuous shedding by the small bowel cells of its lining, and to the considerable mitotic activity of this organ.
BRIEF SUMMARY OF THE INVENTION In order to make possible a massive irradiation of the afflicted organs, while at the same time avoiding excessive irradiation of the radiation-sensitive intestines, and especially the small bowel, means are provided according to the present invention for moving the intestines out of the path of the radiation when same is used for irradiating the afflicted organs. The device according to the invention is a special catheter which is inserted into the intestines before the radiation treatment, which can be left in place for some time in this position, and which makes it possible to move the intestine out of the path of the irradiating beam.
The novel catheter made in accordance with the invention is flexible and of elongated shape, and includes ferromagnetic material enabling it, when inserted into the cavity of the body part, such as the intestine, to be attracted by a magnet external of the body, in order to manipulate the catheter and the body part therewith.
Preferably, the ferromagnetic material is in the form of beads.
In one described embodiment, the ferromagnetic beads are enclosed within a tube of inert resilient material, and in another described embodiment they are strung on a flexible core, such as string, the beads being coated with inert material.
Further features and advantageous of the invention will be apparent from the description below.
BRIEF DESCRIPTION OF THE DRAWINGS The invention is herewith described, by way of example only, with reference to the accompanying drawings, wherein:
FIG. 1 is a longitudinal sectional view of a part of a catheter constructed in accordance with the invention;
FIG. 2 illustrates a variation in the catheter construction of FIG. 1; and
FIG. 3 illustrates another form of catheter constructed in accordance with the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 illustrates a catheter particularly for insertion into the intestines for moving the intestines out of the path of radiation when the same is used for irradiating an afflicted organ The catheter of FIG. 1 includes. a hollow tube 2 of inert resilient material and a plurality of members or beads 4 of iron or other ferromagnetic material.
The length of the catheter is about one to several meters, and its diameter is between 3 to 8 mm. The tubing 2 is of a biologically acceptable material of adequate resilience, such as latex, silicon rubber or the like, of adequate wall-thickness to provide some degree of rigidity, yet supple enough to make it possible to follow the turns and bends of the intestines when inserted in same. A wall thickness of about 0.3 mm to L0 mm has proved satisfactory both for silicon rubber and for natural latex tubing.
Within the tubing there is provided the plurality of spherical or ellipsoid ferromagnetic beads 4 adapted to be strongly attracted by a magnet. The outer diameter of these beadsis chosen in such manner that they are held in place by the resiliency of the tube 2. It has been found that best results are obtained with oblong, ellipsoidal beads having a ratio of radii of about 1:2.
The ratio of magnetisation to the magnetic field applied shows that for prolate ellipsoids the best results are at a ratio of 1:2, as indicated above. With ellipsoids of very elongated shape there is a substantial torque, and this is a drawback for the intended use. No problem of torque exists of course with spherical beads.
Very good results were obtained with iron ellipsoids of a ratio of radii of about 1:2 of about 5 mm small diameter, inserted in a tube of 7 mm outer diameter, of 1 mm wall-thickness, and of 2 meter length.
According to a further embodiment of the invention as shown in FIG. 2; the external tube 12 includes a sequence of such iron beads 14 alternating with beads 16 of similar shape but of plastic material. The beads are positioned close to each other in the tube and some space is left if desired between the beads in order to facilitate the bending of the tube. It is of course possible to use any desired sequence of ferromagnetic beads 14 and of plastic beads 16, and also to use such beads of slightly different radius or shape.
According to a further embodiment of the invention as illustrated in FIG. 3, the catheter comprises a plurality of ferromagnetic beads 24 (if desired in a sequence with beads of plastic material) of spherical or ellipsoid shape strung on a suitable core 28 of string of adequate strength. Core 28 may also be a rod or hollow member of plastic or the like of small diameter. The most simple, yet satisfactory material for the spherical or ellipsoid beads is soft iron, and this is advantageously coated with a coating of plastic material 30 which is inert towards the environment of the gastrointestinal tract and which is biologically acceptable. The plastic coating 30 also reduces or eliminates the danger due to secondary radiation which may result from the incidence of primary radiation on the ferromagnetic beads, if the catheter or part of it remains in the path of the primary radiation used for the treatment of the patient.
The foregoing constructions provide an optimum of flexibility, while at the same time avoiding a bunching together of several members of the chain-like structure, either due to the peristaltic movement or due to the combination of the peristaltic movement together with the influence of the external magnetic force used to move the part of the intestine into which the catheter is inserted from the path of the radiation used for treatment.
First experiments were made by the direct introduction of ferrite powder into the intestines of a dog. This experiment proved that it is feasible to move the intestines by the application of an external magnetic field on the ferrite contained in same. The loops of the intestines could thus be moved sufficiently for the intended results.
After having proved the feasibility of such movement, experiments were continued with gastrointestinal catheters made of ferromagnetic beads. In animal experiments the catheter was inserted and soft X-rays to about 40 KV were used for monitoring the movement of the intestinal loops due to the application of an external magnetic field on such catheter. With guinea pigs a loop of the intestine was moved by means of an external horseshoe magnet and pulled towards the magnet in such manner that the external skin was raised appreciably and pulled into the gap of the horseshoe magnet. The animal was drugged and maintained in this position for hours after which the magnet and the catheter were removed. Histological examination showed no damage to the intestinal tissue. The natural movement of the material in the intestines was not affected by the presence of the catheter.
Further experiments were carried out with dogs. A catheter according to FIG. 1 and comprising a plurality of iron beads of ellipsoidal shape of 1:2 ratio of radii of 3 mm diameter (small radius) in a silicon rubber tubing of 0.6 mm wall thickness was inserted through the mouth or via a small incision made in the small intestine. When a magnetic field was applied from the outside of the body by means of a magnet having a field strength of 6,000 oersted at the face of the magnet, with a 2-inch iron core diameter, this moved the catheter together with the intestine for a sufficient distance.
Similar experiments were made with the FIG. 3 form of the catheter, consisting of a plurality of plasticcoated iron ellipsoids strung on a suitable string, and satisfactory results were obtained.
A number of experiments were carried out with humans. A gastrointestinal catheter according to the FIG. 1 form of 1 meter length and 3-7 mm outer diameter of the tubing ensheathing the iron beads, was inserted into the intestines. The application of a magnetic field from outside the body, of about 6 K-oersted moved the catheter and the loop of the intestine in the desired direction.
In the FIG. 3 form, the provision of a coating 30 of plastic, such as polyethylene or the like, of adequate thickness, on the iron beads prevents any secondary radiation from damaging the intestines, if the catheter is in part in the path of the radiation used for the treatment. In practice it is advisable to examine the patient by X-rays prior to the radiation treatment in order to ascertain that the loop or loops of the intestine, together with the catheter inserted thereinto, have been moved away.
In guinea pig experiments Alnico 5 magnets were used as the external magnets for attracting the catheter and the body part therein. With humans it is advisable to use superconducting magnets of great field strength and comparatively small size.
Catheters of about 4-7 mm outer diameter may be left in the intestines for quite prolonged periods without any adverse effect. Examinations carried out after 10 days showed that no damage was caused by the catheter and that it did not interfere with the natural body activities. During such prolonged periods it is possible to carry out an intensive radiation treatment.
It is clear that the above description is by way of example only and that many modifications, changes and other applications of the catheters described may be made.
What is claimed is:
1. Magnetic apparatus insertable into a body cavity, for displacement of internal body organs from a region of applied radiation by means of a magnet disposed externally of the body, characterized in that it is of elongated shape, flexible and includes an elongated flexible tubular member of substantially inert resilient biologically acceptable material;
a plurality of ellipsoidal beads of soft iron having major and minor axes substantially in a 2:1 ratio respectively, axially disposed with their major axes parallel to the longitudinal axis of said tubular member and in closely adjacent spaced relationship therein over a substantial length thereof, said soft iron ellipsoidal beads being fixed in said spaced relationship by said resiliency of said flexible tubular member;
said magnetic apparatus being adapted when inserted into the cavity of a body part, to be uniformly and unidirectionally attracted by a magnet external of the body for desired displacement of said body part as aforesaid substantially without the application of torque to said beads.
2. Magnetic apparatus insertable into a body cavity, for displacement of internal body organs as defined in claim 1, wherein said flexible tubular member also includes plastic beads alternating with and spaced from said soft iron beads and similarly fixed in said spaced relationship by said resiliency of said flexible tubular member.
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