SPATIAL AND TEMPORAL VARIATIONS IN PACEMAKING AND CONDUCTION IN THE ISOLATED RENAL PELVIS

In renal pelvis preparations isolated from the sheep, the location of the pacemaker and the pathway of conduction of the electrical impulse in the pelvis were analyzed in detail. An electrophysiological acquisi tion system was used allowing simultaneous recordings from 240 extrace llular electrodes. Reconstruction of the spread of activity showed tha t the site of the pelvis pacemaker was, in virtually all cases, locate d at the pelvicalyceal border and never in the body of the pelvis or i n the area of the pelviureteric junction. One single pacemaker was res ponsible for a particular spread of activation, and fusion of activity originating from two or more pacemakers did not take place. Furthermo re, spontaneous shifts of the pacemaker could occur from one site to a nother along the pelvicalyceal border. Conduction from the site of the current pacemaker to the pelviureteric junction and the ureter was sl ow, inhomogeneous, and contorted. Multiple instances of partial or tot al conduction block were seen at all levels in the pelvis and were not restricted to the pelviureteric junction. The occurrence of conductio n block did not seem to be related to the length of the preceding inte rval, implying that the refractory period did not play a major role in the genesis of intrapelvic conduction block. In conclusion, high-reso lution mapping of the renal pelvis is possible and reveals location an d behavior of the pacemaker and documents inhomogeneities in conductio n and conduction block.