Abstract: A guiding introducer for use in the right atrium comprised of a first, second and third section wherein the first section is a generally elongated straight section wherein merged with the distal end of the first section is a second section which is curved upward in a longitudinal curve wherein the distal end of the second section is merged with the third section. The guiding introducer is for use in sensing, pacing and ablating procedures in the right atrium of the human heart.

Abstract: A guiding introducer for use in the left atrium comprised of a first, second and third section wherein the first section is a generally elongated straight section wherein merged with the distal end of the first section is a second section which is curved in a compound curve, first curving upward in a first longitudinal curve and simultaneously curving to the right in a second longitudinal curve, wherein the second section merges with the third section wherein said third section is a third longitudinal curve wherein the plane of the third section is angled upward at an angle of approximately 25 to about 60 degrees from the plane of the first section and wherein substantially all of the third section is coplanar.