This disclosure is directed to a catheter having an asymmetric basket-shapedelectrode assembly at the distal end of the catheter body formed from aplurality ofspines with electrodes. The plurality of spines are radially distributedacross a firstcircumferential portion. One or more counter spines are radially distributedacross aremaining second circumferential portion. Diagnostic electrodes are arrayedacross thespines, while the counter spines may have one or more reference electrodes.
