an ep catheter includes a tubular body having a proximal region , a neck region , and a distal portion predisposed into a single shallow helical fixed - diameter loop configuration and including a plurality of diagnostic electrodes . in deflectable catheter forms , at least one activation wire extends through at least a portion of the proximal region of the catheter body and is adapted to deflect the up to approximately 180 degrees relative to the proximal region . the catheter can be operated manually by a clinician or via a clinician - surrogate such as a computer processor - controlled surgical system . in addition , a variety of localization , visualization , and / or orientation - specific elements can be incorporated into the devices described , depicted , and claimed herein .