Over the past two decades therehave been several attempts to devel-op an artificial bladder. To a largeextent appropriate results for theuse of alloplastic materials have

been mentioned in lectures, buthave not been published so far.The reason for this was, on the onehand, the lack of development ofsuitable materials, and on the othera lack of ideas for realistic, activeconcepts.As a clinical user of bladder substi-tute systems, urology supports atpresent, operative processes inwhich the use of a separated seg-ment of intestine play the mainrole.Clinical indications for the use ofbladder substitutes are shrunkenbladders as a result of infection orradiation dammage, or in seldomcases of congenital bladder mal-formation. The main areas for sub-stitute bladders are tumours of thebladder.There are approximately 18.000cases of tumours of the bladdereach year in Germany alone.Approximately double so manymen are affected (12.500 cases) aswomen (5.100 cases). The number

of women affected is rising drama-tically, however, most probably dueto the fact that the number ofwomen smokers is becoming larger. The radical cystectomy in women,i.e., a continent urinary divertion asa substitute for their own bladderpresents a challenge because thefemale does not have the sphinctermuscle that the male has. Thebladder is the 4th most frequentlocalisation of cancer in men, andthe 8th most frequent in women.The frequency of the urothel carcinoma in Europe in 1990 was 66.518 (men: 52.213, women:14.305), corresponding to a fre-quency of 28,5/100.000 in men and5,2/100.000 in women. The highestrate of males was recorded in Italyand Spain, whereas in Great Britainand Sweden the highest rate offemales was recorded. The lowestrate for men was in Ireland and forwomen in Luxembourg. In USAapproximately 55.000 new cases arerecorded each year.

Artificial UrinaryDiversion System

In our part of the world all themes associated with urology are tabu,whereas in Anglo-American countries the scientific and social aspects are openly discussed andinformation is given.Articles for incontinence are often sold in Germany under the counter, but in USA andCanada one comes across products in advertising and in internet and the discussion oftheir use and merits is regarded as one of the most normal things in the world.Themes of research and development are often categorized according to their socialstatus.It was a message in Canadian internet that „Incontinence may destroy your life“,accompanied by a disturbing picture, that stimulated us to research openly and intensively, against the general tabus in society and to research for a solution.

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Fig. 1: Prof. Wassermann fits the dummyafter a cystectomy in the operation’s situ,r.: Dr. Eichenauer, l.: Dr. Döhn

In the majority of cases the substi-tute bladder entails the integrationof parts of the large and smallintestine in order to allow for thedevelopment of a urinary reservoirand for urinary diversion. So farthere is no alternative construction,so that these variable intestinesystems are considered the „golden

standard“. These processes, how-ever, have considerable possibilitiesof complication and a high rate offollow-up problems.An operative urinary divertion,uses considerable parts of theintestine that are cut off from thenatural intestinal continuity, ormodify the configuration of theintestine. Considering the burdenof the operation on the patient, thepost-operative recovery and themorbidity rate as a result of theprocess, the use of the artificialsubstitute bladder instead of theabove methods could have consi-derable advantages.Purely biological substitute sys-tems, e.g. the xenograft transplantsof the pigs’ bladder, or that of theape, or rather the transplantation of human or animal „acellularmatrix“, are hardly likely to be realised clinically because of thenumerous, in particular, immuno-logical and functional problems.According to those acting in thisfield, it is not certain if a clinicalsubstitute will be possible.

A new realistic conversion for thedevelopment of an alloplastic sub-stitute bladder that operates whenit is adapted to the physiologygains, on the one hand, from theavailability of new biocompatiblematerials, and on the other handfrom the miniaturising successeswith actuators (pumps, closing and

locking systems ) as well as efficientTET, i.e. transcutaneous energy-transfer and supply systems.The medical wishes and needs ofsuch an artificial system are easilydefined:an alloplastic semi-elastic capsule, that

is energetically self-sufficient , teleme-

tric and able to be coded and control-

led externally. It must also be indivi-

dually adaptable as a module and can

be implanted as a whole.

This may be a short definition, butit represents an enormous technicalchallenge. Ten years of interdisci-

46 Urinary Diversion System

plinary, intensive research anddevelopment have taken place withthe financial support of the Minis-try for Education and Research andwith support from the industry, inparticular from the owner of theESKA Holding, Dr. Hans Grundei.

All the actuating and energy-tech-nical parts have to be integratedinto the hard part of the capsule ofthis new product, i.e., an activetechnical sub-system may not befound outside the capsule. Neithera supply connection nor any othersystem component may protrudethrough the outer skin. The systemis not visible after the operation.The only elements that are im-planted subcutaneously are: anenergy transfer element necessaryfor the control of transmission, aninformation system for the amountin the bladder, and an individuallycodable chip for the commense-ment of the emptying process.The only sign of the presence ofan artificial device in the abdomenand pelvis is the charging and con-trol display that is attached to a beltwhich must be applied manually.There are already technical solu-tions for the signal and transfer ele-ment used elsewhere in the medi-cal-technical field of substituteorgans.However, a 1:1 takeover of suchproducts is not possible in particu-lar because of the special urologicaldemands on such devices. These

Fig. 2: The first hollow cavity varieties of a dummy made of PU

What makes the concept ofthe implant geometrically,

electromechanically andelectronically so unique?

47Urinary Diversion System

Fig. 9: Sequential scheme for a typical cycle of emptying and filling, and the electric supply of the implanted artificialbladder

Subcutaneous implanted induction coil

Vibration alarm

Control receives external signal

Batteries are recharged

Differing height adaptable device on the promontory

Reservoir refills

External recharging device is applied for transcutaneous energy and signal reception

1. Batteries deliver energy forpumps, valves, and controland discharge

2. Valve opens

3. Pump starts4. Urine flows

5.Reservoir

is emptied

include: high density of energy,permissible and compatible fre-quencies, coding and dislocationcorrections.The solutions to the developments– already begun in 1992 in theabove-mentioned fields – are super-ior to the American concepts.

The idea of an implantable capsulewas developed in 1995 and 1996 asa result of integration and adaptionwork on corpses and segments ofcorpses. This work took place inthe Institute of Pathology andAnatomy of the MUL in manyiterative steps and it producedmany valuable impulses. Numeroushollow cavities were developed,manually injected and spun and opti-mized again and again (see fig.2).It caused great consternation whenboth doctors and technicians reali-sed that although after much hardwork, the forms that had beendeveloped were well-suited to thetopology of corpses but not at all

suitable for implantation in theliving organism. All our work wasfutile, and we, including our medi-cal partner, Prof. Dr. DieterJocham, Director of the UrologyClinic of the University of Lübeck,were thrown back many months.Pioneer work can lead down pain-fully wrong tracks.The really decisive sophistication,and with it the new lead in inven-tion occurred with the geometricdefinition. This new position wasproduced out of biocompatiblematerial with a functional pattern,

and fitted into the living bodyduring an operation (fig. 1).The result is reported in the Ger-man patent registration No. DE199 12 472.8 and in the internatio-nal registration No. WO 00/56246.

These include the detailsof a main function, bymeans of 6th grade poly-noms described in theiroptimum form. The innovative processresults from the fact thatduring an operation, in afirst step a dummy(made up of three diffe-rent sections) has to be fitted optimally. The

dummy can be re-used after sterili-sation. In a second phase the realimplant, which has been formedfrom selected modules is fitted.This process is easier for the pa-tient and requires less resources.

The assessment of the mechanicaldetrusor process in order to emptyan artificial bladder can be illustra-ted by a spindle with the aid ofcompressing bellows in time-lapseprocess.

The experiment using sphericalprecision spindles and bellowsmade out of polyurethane 1303ended after approximately 88.000cycles. This meant that the aim ofapproximately 85.000 cycles wasmore than reached. This repre-sents a duration of use of approxi-mately 15 years (see fig. 4).The so-called U8/U4 experimentsare in automatic continuous opera-tion. Polyurethanes, silicones, pumpsand valves using artificial urine, andnatural human urine, kept at bodytemperature are tested (fig. 5).Further emptying technologies, inparticular with regard to efficiency,safety and ergonomy were tested andcompared within the research worksupported by the BMBF (fig. 6).

48 Urinary Diversion System

Work on the detrusor function

Fig. 3: Upper, middle and lower modules in varying sizes

Success in the in vivofunctional test

Fig. 4: Time-lapse experiment installation. The PU bellows have a lifetime of more than15 years

Fig. 5: Fully automatic continuous test ofbellows,valves, pumps and tubes at simu-lated body temperature

that was previouslyclosed for safety isreleased. After severalcycles of miction, e.g.after two days, es-pecially when a visitto the Oktoberfestwas included, the rundown batteries haveto be recharged. Thecapacity of the batte-ries can be read onthe LED display.The next step is to establish proof of the prototype’s ability to function in

animals and in clinical trials. Wehave already had many inquiriesabout, and requests for the artificialbladder.

When the trials are successfulthese people can be helped.

It would be possible to add to thelist of successful experiments. The following two results are par-ticularly interesting:1. Polyurethane bellows: mechanical,electric and electronic componentsof the pneumatic experimentalinstallation, including control havereached the number of 5,2 mio.cycles with no remarkable damages( see fig. 8). The additional impor-tant insight gained by this, concer-ning the form and folds, andemploying diverse polyurethanes,guarantees the success of the pro-duct. 2. The FHM and the MUL deve-loped three movement tables forsimulation of movement in theurological area. These all functionin the same manner, but are techni-cally different so that they representthe possibilities of speed and move-ment in the pelvis. These movementtables have been developed accor-ding to the investigations of the

ETH Zurich and the correspondingalgorithms (see our patent registrati-on No. DE 199 12 473.6). These so-called hip-movement tests alsocovered the question ofthe artificial aging of thematerials by means ofthermic over-heating(see fig. 7).In order to understandthe function of theimplanted substitutebladder we shouldimagine in fig. 9 thatthe tissue is transpa-rent and that one canonly see the pelvis andthe spine. When thecontents of the bladderhave reached a certain level there isa vibratory alarm, that can also beaccoustic or optical by choice.Having been to the toilet the pa-tient gives his own personal codeinto the device.The recharged batteries (showngreen) supply the energy for thecontrol, for the pump function

and for the use of the valves. Theemptying processoccurs quite nor-mally as with the natural bladder, either standing orsitting.When the bladderis completely emptythe antireflux valve

Contact:

Munich University of Applied SciencesFaculty of Elektrotechnik und Informationstechnik

Lothstr. 34D-80335 MünchenGermany

Tel. +49 - (0)89 / 12 65 - 29 03Fax +49 - (0)89 / 12 65 - 29 30email: wassermann@ee.fhm.edu

Prof.H. Wassermann

49Urinary Diversion System

Fig. 7: Movement hip-table for the urodynamic component testthat at the same time tests the artificial aging of the materials

Fig. 8: Pneumatic test on fold and cylinder bellows withdiffering Shore-forces

Further technicalexperiment installations

Fig. 6: Fluid kept at constant temperature of 37° C, pumped electrohydraulically in anticyclic by the bellows(e.g. PU1303) for a continuous test of polymer material, diverse pumps and valve systems, using varyingdegrees of pressure and fluid pressure speeds