A cardiac arrhythmia ablation catheter that has a highly flexible tubular distal segment particularly adapted for navigating and exploring a ventridular cardiac chamber forming a lumen through its length which connects to a distal electrode-carrying tip which is provided with an independently rotatable tip electrode mounted at the distal end tip of the distal tip section and adapted to engage and roll over the internal surface of a ventricular heart chamber of interest without rotation of the catheter itself. A wire deflection control system is provided to deflect the distal tip system of the distal catheter section in a controlled manner and a hand-operated control is provided to control the rotation of the rotatable tip electrode.