Basket style cardiac mapping catheter having an atraumatic, metallic two-part distal tip for detection of cardiac rhythm disorders

1. A system for sensing multiple local electric voltages from endocardial surface of a heart, comprising:

a first elongate tubular member having a lumen, a proximal end and a distal end;

a basket assembly comprising:

a plurality of exposed electrodes;

a plurality of flexible splines for guiding the plurality of exposed electrodes, said plurality of flexible splines having proximal spline portions, distal spline portions and medial spline portions therein between, wherein the splines comprise an outer surface, an inner surface and two side surfaces, and wherein the splines further comprise alignment members projecting laterally outwardly from the two side surfaces at the distal spline portions;

a proximal anchor for securably affixing the proximal spline portions, wherein the proximal anchor is securably affixed within the lumen of the first elongate tubular member at the distal end of the first elongate tubular member; and

a distal tip comprising a top part and an opposed bottom part;

said top part comprising an atraumatic top surface and an opposed bottom surface;

said opposed bottom surface of said top part comprising a plurality of spline alignment posts disposed therefrom defining a lateral portion of said distal tip, wherein adjacent pairs of the spline alignment posts define spline channels there between, wherein interior portions of the spline alignment posts are spaced apart to define a spline alignment portion, and wherein the alignment members of the splines are securably disposed within the spline alignment portion of the top part;

said opposed bottom part comprising an atraumatic bottom surface and an opposed upper surface;

said opposed upper surface of said bottom part comprising a raised central portion configured to fit within the spline alignment portion of the top part;

wherein the splines have reduced lateral extents between the two side surfaces to define reduced spline widths at said distal spline portions near the distal tip and proximal to the alignment members as compared to spline widths at said medial spline portions;

wherein spacing between adjacent pairs of the spline alignment posts is greater than the reduced spline widths and less than lateral extents between the two side surfaces at said medial spline portions;

wherein the spacing between adjacent pairs of the spline alignment posts is less than lateral extents of the laterally projecting alignment members at the distal portions of the splines;

wherein the basket assembly has a radially expanded non-cylindrical shape; and

wherein the splines comprise a superelastic material.

2. The system of claim 1 , further comprising:

a second elongate tubular member having a lumen, a proximal end and a distal end, the second elongate tubular member being slidably disposed over the first elongate tubular member;

wherein the basket assembly is slidingly compressible to fit within the lumen of the second elongate tubular member;

wherein the basket assembly has a substantially cylindrical shape when compressed within the lumen of the second elongate tubular member; and

wherein the basket assembly has said radially expanded non-cylindrical shape when not compressed within the lumen of the second elongate tubular member and disposed past the distal end of the second elongate tubular member.

3. The system of claim 1 , wherein each spline channel of the distal tip contains only one distal spline portion.

4. The system of claim 1 , wherein each spline channel extends from the bottom surface of the top part of the distal tip to the upper surface of the bottom part of the distal tip.

5. The system of claim 1 , wherein, when said basket assembly is in said radially expanded non-cylindrical shape, the splines extend beyond the distal tip and comprise excurvate bends beyond the distal tip to bend the splines back towards the proximal anchor.

6. The system of claim 1 , wherein the splines approach the distal tip at an angle of about 90° as measured from a line segment between the proximal anchor and the distal tip along the longitudinal axis.

7. The system of claim 1 , wherein the splines further comprise spline ends and further wherein the spline ends terminate at the proximal portions of the splines.

8. The system of claim 1 , wherein said distal tip is a metallic distal tip.

9. The system of claim 8 , wherein the top part of the distal tip and the opposed bottom part of the distal tip are welded together to secure the distal spline portions within the distal tip.

10. The system of claim 1 , wherein the atraumatic top surface of the top part of the distal tip is domed shaped.

11. The system of claim 1 , further comprising an elastomeric material disposed within the distal tip to minimize tip voids and open spaces at the distal tip.

12. The system of claim 1 , wherein the superelastic material of the splines comprises nitinol.

13. The system of claim 1 , wherein the superelastic material of the splines comprises a shape memory material.

14. A method for assembling a system for sensing multiple local electric voltages from endocardial surface of a heart, comprising:

providing a first elongate tubular member having a lumen, a proximal end and a distal end;

providing a plurality of exposed electrodes;

providing a plurality of flexible splines for guiding the plurality of exposed electrodes, said plurality of flexible splines having proximal spline portions, distal spline portions and medial spline portions therein between, wherein the splines comprise an outer surface, an inner surface and two side surfaces, and wherein the splines further comprise alignment members projecting laterally outwardly from the two side surfaces at the distal spline portions;

providing a proximal anchor for securably affixing the proximal portions of the splines, wherein the proximal anchor is securably affixable within the lumen of the first elongate tubular member at the distal end of the first elongate tubular member; and

providing a distal tip comprising a top part and an opposed bottom part;

said top part comprising an atraumatic top surface and an opposed bottom surface;

said opposed bottom surface of said top part comprising a plurality of spline alignment posts disposed therefrom defining a lateral portion of said distal tip, wherein adjacent pairs of the spline alignment posts define spline channels there between, wherein interior portions of the spline alignment posts are spaced apart to define a spline alignment portion, and wherein the alignment members of the splines are securably disposed within the spline alignment portion of the top part;

said bottom part comprising an atraumatic bottom surface and an opposed upper surface;

said opposed upper surface of said bottom part comprising a raised central portion configured to fit within the spline alignment portion of the top part;

wherein the splines have reduced lateral extents between the two side surfaces to define reduced spline widths at said distal spline portions near the distal tip and proximal to the alignment members as compared to spline widths at said medial spline portions;

wherein spacing between adjacent pairs of the spline alignment posts is greater than the reduced spline widths and less than lateral extents between the two side surfaces at said medial spline portions;

wherein the spacing between adjacent pairs of the spline alignment posts is less than lateral extents of the laterally projecting alignment members at the distal portions of the splines;

disposing the splines within the top part so that the alignment members of the splines are disposed within the spline alignment portion of the top part and so that the reduced spline widths at the distal spline portions are disposed within the spline channels;

aligning the top part and the bottom part to dispose the raised central portion of the upper surface of the bottom part into the spline alignment portion of the top part; and

securing the top part and bottom part to one and the other.

15. The method of claim 14 , wherein each spline channel of the distal tip contains only one distal spline portion.

16. The method of claim 14 , wherein each spline channel extends from the bottom surface of the top part of the distal tip to the upper surface of the bottom part of the distal tip.

17. The method of claim 14 , wherein top part of the distal tip and the bottom part of the distal tip are metallic members.

18. The method of claim 17 , wherein the step of securing the top part and bottom part to one and the other further comprises welding the top part and bottom part to one and the other.

19. The method of claim 14 , further comprising:

securably affixing the proximal portions of the splines at the proximal anchor to form a basket assembly; and

securably affixing the proximal anchor within the lumen of the first elongate tubular member at the distal end of the first elongate tubular member.