1Advanced Platform Technology Center of Excellence, Louis Stokes Cleveland Veterans Affairs Medical. Center, Cleveland, OH;. 2. Urology Institute, University ...
CYSTOSCOPIC IMPLANTATION OF A WIRELESS IMPLANTABLE PRESSURE SENSOR IN A LARGE ANIMAL MODEL Elizabeth Ferry,1,2 Steve Majerus,1,3 Hui Zhu,1,2 Steven Garverick,1,3 Margot S. Damaser1,4,5 1Advanced Platform Technology Center of Excellence, Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, OH; 2Urology Institute, University Hospitals, Cleveland, OH; 3Department of Electrical Engineering and Computer Science, Case Western Reserve University, Cleveland, OH; 4Department of Biomedical Engineering,, Cleveland Clinic, Cleveland, OH; 5Glickman Urological and Kidney Institute, Cleveland Clinic, Cleveland, OH Introduction: Current methods of determining intravesical pressure are limited in their snap-shot nature and artificial environment, in addition to not being amenable to chronic or ambulatory settings. Chronic bladder pressure monitoring could enable conditional neuromodulation, increasing effectiveness and efficiency. An ideal chronic pressure sensor must be wireless, fully internalized, non-irritative, out of contact with the urine, and placed in a minimally-invasive manner. We have developed a wireless implantable micro-manometer (WIMM) that consists of a micro-battery, pressure transducer, and custom integrated circuit with instrumentation, telemetry, and power management circuitry. An external radio frequency receiver/recharger receives pressure telemetry and intermittently recharges the implanted micro-battery, enabling chronic implantation. The device was sized to be compatible with conventional urological instruments, and the form factor permits cystoscopic implantation in a suburothelial location in the bladder. This study aims to evaluate the safety and feasibility of cystoscopic implantation of WIMM devices in a large animal model. Methods: A 59.2 kg female Jersey calf was anesthetized following an IACUC-approved protocol. Cystourethroscopy was performed and a suburothelial pocket was made using an electrode and cystoscopic scissors. The device was placed into the suburothelial pocket by placing the sheath in the pocket mouth, removing the lens, and advancing the device through the sheath. Placement adjustments were performed using the rigid graspers. This process was repeated to test insertion feasibility in several pockets. Fluoroscopic CTrendered cystograms were obtained to assess bladder integrity and device location. Necropsy was subsequently performed after euthanasia. Results: Pocket placement was subjectively more straightforward immediately cephalad to, but not involving, the trigone. Cystograms before and after initial pocket creation were identical and confirmed bladder integrity. Visually, the device was placed completely within the suburothelial pocket in two peri-trigone areas, without urothelium interposition. Adequate placement closer to the dome was subjectively more difficult. Necropsy did not reveal perforation grossly, or on filling with Toluidine blue. Conclusions: WIMM devices may be successfully placed in a suburothelial position using minimally invasive, standard equipment and techniques. Posterior wall locations immediately cephalad to the trigone appear to be optimal. Further survival studies are needed to determine long-term outcomes. Funding: Dept of Veterans Affairs RR&D Merit Review 1I01RX000443-01
Figure 1. The implanted pressure sensor prototype inside a clinical 24-French cystoscope sheath.
