An improved catheter particularly useful for tubular regions at or near the heart has a distal assembly having at least two spines, each having a proximal end fixed to the catheter and a free distal end. Each spine has a support arm supporting the spine in a generally L-shaped configuration when the spine is in a relaxed, neutral state and in a generally U-shaped configuration when the spine is inserted into a tubular region. The spine has a proximal portion and a distal portion that may be straight or curved or zig-zagged. Each spine carries a tip electrode and at least one ring electrode that come into contact simultaneously with heart tissue for ablation and/or sensing electrical activity along two different circumferences of the tubular region simultaneously.
