Pilot study evaluating ureteric physiological changes with a novel 'ribbon stent' design using electromyographic and giant magnetoresistive sensors

Objective To test a novel 'ribbon stent' (RS) design using an extraluminal bipolar electromyographic (EMG) and giant magnetoresistive (GMR) sensor system to characterize ureteric responses. MATERIALS AND METHODS In all, 11 female domestic pigs were divided into three groups to evaluate ureteric physiology: group 1 (two pigs) with an unstented ureter, group 2 (three) with a standard 6 F ureteric stent, and group 3 (six) with the RS. For all groups EMG/GMR evaluation was performed at baseline, immediately after stenting, and at 3 and 7 days after stenting. All pigs underwent standardized retrograde ureteropyelogram evaluation at these time points, and after the final evaluation the pigs were killed and the urinary tract was harvested for histopathological evaluation. RESULTS One stent in group 3 could not be deployed due to a problem with ureteric access. For groups 1, 2 and 3 the ureteric peristaltic activity was 109, 63, 72 events/h at baseline (P = 0.49); 61, 70, and 66 events/h immediately after stenting (P = 0.97); 66, 0, 8 events/h at 3 days after stenting (P = 0.002); and 61, 12, 0 events/h at 7 days after stenting, respectively (P = 0.049). CONCLUSION The RS was deployed easily and safely in the porcine model using a standard technique. As with a standard stent, there was significant ureteric dilation and decrease in peristalsis with the RS.