US3543761A - Bladder stimulating method - Google Patents

Description

O I v Umted States Patent 1111 3,543,761

{72] Inventor William E. Bradley [56] References Cited 1 N gf g'm UNITED STATES PATENTS U P 2,590,876 4/1952 Landauer 128/417 [22] Flled 01.1.5, 1967 3,236,240 2/1966 Bradley 128/421 [451 Pawn 3 40s 11s 10/1968 Ha fors 128/418 [73] Assignee The Regents of the University of Minnesota g Minne li Mi t Primary Examiner-William E. Kamm a corporation of Minne ota Auomey- Burd. Braddock & Hart:

[54] BLADDER STIMULATING METHOD A's." An

. apparatus and method for 1mp1antat1on 1n 1 Clam" 5 Drawing Figs the body of an animal to stimulate the bladder without stimu- [52] U.S.Cl 128/421, lating nearby muscles. and the method of so stimulating the 128/418 bladder. The electrode structure of the apparatus includes a [51] lnt.CI A6111 1/18 first plurality of electrodes, each of which is surrounded by [50] Field of Search 128/404- one of a second plurality of electrodes to limit the stimulation to a series of spaced spots.

BLADDER STMULATINGMETIIOD BACKGROUND or THE INVENTION This invention relates to a method for artificially and electrically stimulating the bladder of persons who have lost the ability to voluntarily empty the bladder because of injury or disease;

This invention was made under a grant from the United States Government through the Department of Health, Education and Welfare.-

This apparatus and method ,is an improvement over that described in my US. Pat. No. 3,236,240. It has been discovered that use of the apparatus there disclosed is not always completely satisfactory. That apparatus utilizes spaced apart electrodes to stimulate large areas of the bladder smooth muscle with volitionally generated electrical signals. It has been found that stimulation of such large areas sometimes results in stray electrical signals causing stimulation of nearby muscles in an undesired manner. Specifically, the stimulating signal causes the bladder to attempt to contract as desired but also causes contraction of the external sphincter, thereby inhibiting the evacuation of fluid from the bladder.

SUMMARY OF THE INVENTION In order to overcome the above described prior art drawback, an improved method has been developed to stimulate a number of separated spots' on the smooth muscle of the bladder with electrode structures that prevent stray signals from stimulating the sphincter or other nearby, muscles in the pelvic floor. The method ofv the present invention utilizes a plurality of spaced first electrodes, connected in parallel, each of which is electrically guarded by a second electrode so that the stimulating signal is confined to small spots between each first electrode and the second electrode which guards it. The

invention is more fully described in the drawing and detailed description which follow.

BRIEF DESCRIPTION OF THE DRAWING DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now'to FIGS. 1, 2 and 2A, a stimulating signal generating means, generally designated 10, is encased in a sterilizable, inert, nonirritating andnontoxic protective and insulating mass 11, preferably .of synthetic resinous material. Substances such as silicone rubber, silastic resins, tetrafluoroethylene polymers, vinyl chloride and the like, are suitable materials for use as the encasing or the encapsulating material. Pure naturalrubber may also be used.

Extending outward from the signalgenerating means is an encapsulated conductive lead structure, generally designated 12. Encapsulated lead structure 12 includes a pair of electrically conductive flexible leads 13 and 14 which are connected between the output of stimulating signal generating means 10 and a pair of'buss bars 15 and 16, respectively. From buss bar 15, a plurality of flexible leads I7 extend to an exposed electrode structure, generally dcsignated 25, with each lead 17 having one end connected to an annular electrode 1 8. From buss bar 16, a plurality of flexible leads extend to exposed electrode structure with each lead 20 having its free end connected to a circular electrode 21, which is positioned inside of one of electrodes I8. The structures carrying leads I7 and 20 are generally designated 19.

Electrical leads 13, 14, 17 and 20 are constructed 'of any flexible good electrical conductor, but are preferably formed of an alloy of about 90 percent platinum and about 10 percent iridium. The leads may be flat or coiled as shown. Exposed electrodes, 18 and 21 may be formed from any inert nontoxic and nonirritating electrically conductive material. Platinum or platinum-iridium alloys are preferred materials but other materials such as tanalum, gold. silver. and alloys of these metals or surgical grade stainless steel may also be used.

Conductive leads 1.3; 14, 17 and 20, buss bars 15 and I6, and portions of electrodes 18 and 21 are encased or encapsulated in inert, nontoxic material 22 which forms a unitary impervious coating with covering 11. Thus, only portions of electrodes 18 and 21 are exposed. Encapsulating material 22 performs the dual function of encapsulating the leads and supporting each of electrodes 18 in guarding relation to one of electrodes 21 so that the current path is confined to a small area between each electrode 2] and the electrode I8 which guards it.

The preferred exposed electrode structure, as shown in FIGS. 1 and 2, utilizes electrodes 21 having a circular surface which contacts the bladder muscle. Electrodes 18 are constructed so as to have an annular surface contactingthe bladder muscle so as to entirely surround the circular area contacted by electrode 21. However, electrode 21 may contact an area in the shape of any geometrical FIG, and guard ing electrode 18 may take the form of any closed geometrical FIG. which surrounds the area contacted by electrode 21. The diameter of the contact surface of annular guarding electrode 21 is preferably 1 centimeter or less so that several can readily be sutured to a collapsed human bladder. The contact area of electrode 18 is preferably small enough that substantially the entire area within the circle contacted by electrode 21 carries current.

Encapsulating material 22 has a series of holes 23 spaced around each guarded electrode structure. These holes are included for ease in suturing the electrode structures to the bladder wall at spaced apart locations. It has been discovered that fromtwoto eight separate spots, and preferably four, should be stimulated to achieve satisfactory evacuation of the bladder of a human. When four structures are used, they are placed around the neck of the bladder at approximately equal intervals.

' FIG. 3 discloses a block diagram of one electrical circuit which can be used to stimulate separated spots on the bladder or other body organ. Stimulating signal generating means 10 is shown containing a parallel resonant circuit 30 which is responsive to an externally generated, radio frequency, oscillatorysignal. Resonant circuit 30 is connected through a rectifier 31 and filter 32 to a pulse generator or multivibrator 33. The output signal from pulse generator 33 appears across conductiveleads Band 14.

generator 33 which has a pair of output terminals 34 and 35..

Pulse generator 33 is preferably constructed to provide 10- 30-volt peak pulses, with one millisecond pulse width, at the rate of 25 pulses per second into a I00 ohm load. The output signal from pulse generator 33 is A-C coupled to leads l3 and 14.

As shown in FIG. 3, it can be seen that the output of pulse generator 33 appears across electrodes 18 and 21 of each electrode structure. Since each of the electrodes 18 is tied to a common point or buss bar 15, they are all at substantially the same potential and substantially no current flows between the spaced apart electrode structures.

FIG. 4 is a modified bladder stimulator, according to the in vention, wherein parts corresponding to those in FIGS. 1-3 are numbered one hundred greater. In FIG. 4, each electrode structure has separate leads which extend into encasing means 111. In this structure, more lead carrying structures exit from encasing means 111, but buss bars, like and 16 of FIGS. 1 and 2, are not required. Elimination of the buss bars and direct connection of each of the leads to one of the output terminals of the pulse generator reduces cost substantially when platinum-iridium leads are used.

The embodiments described are only representative of many variations that are within the scope of the invention which is intended to be limited only by the scope of the following claims.

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