Ablation catheter and method for isolating a pulmonary vein

A catheter assembly for treatment of cardiac arrhythmia comprising:

• a catheter body including:
• a proximal portion,
• an intermediate portion extending from the proximal portion and defining a longitudinal axis,
• a distal portion extending from the intermediate portion and forming a substantially closed loop, the loop defining a central loop axis substantially parallel to the longitudinal axis;
• and
• at least one electrode disposed along the distal portion;
• wherein upon energization, the electrode ablates a continuous, closed lesion pattern in a plane substantially perpendicular to the longitudinal axis for isolating material within the closed lesion pattern.

A method for forming an ablation pattern to electrically isolate a vessel having an ostium from a chamber formed within a patient for treatment of cardiac arrhythmia, the method including:

• selecting a catheter assembly comprising a catheter body defining a longitudinal axis and having a proximal portion and a distal portion, the distal portion forming a substantially closed loop transverse to the longitudinal axis, the loop defining a loop axis substantially parallel to the longitudinal axis, and at least one electrode disposed along the distal portion;
• guiding the distal portion into the chamber;
• directing the distal portion to a position spaced from the vessel ostium, whereby the loop axis is substantially aligned with a center of the vessel ostium;
• advancing the distal portion in a direction parallel with the loop axis such that the loop contacts the chamber wall about the vessel ostium;
• and
• energizing the electrode to ablate a continuous, closed lesion pattern about the vessel ostium to electrically isolate the vessel from the chamber.