Temporary transvenous endocardial lead

• US 5,851,226 A
• Filed: 10/22/1996
• Issued: 12/22/1998
• Est. Priority Date: 10/22/1996
• Status: Expired due to Term

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Williams, Terrell M., Skubitz, Frank L., Herman, Gerald M.
• Primary Examiner(s): Kamm, William E.
• Assistant Examiner(s): EVANISKO, GEORGE ROBERT
• Application Number:
  US08/734,915
• Time in Patent Office: 791 Days
• Field of Search: 607/126-128, 607/130-132, 600/375
• US Class Current: 607/126
• CPC Class Codes: A61B 2017/00469 for insertion of instruments, e.g. guide wire, optical fibre
• CPC Class Codes: A61N 1/056 Transvascular endocardial electrode systems
• CPC Class Codes: A61N 1/057 Anchoring means; Means for fixing the head inside the heart
• CPC Class Codes: A61N 2001/0578 having means for removal or extraction

Abstract

A novel low cost, temporary pacing lead that provides superior torque transfer characteristics and positive affixation to the endocardial wall. The lead system of the present invention provides up to ten times more torque transmission between its proximal and distal ends than may be attained using prior art temporary leads. Additionally, the lead body of the present invention has a ratio of ring electrode surface area to tip electrode surface area that exceeds about 2, and a tip electrode surface area less than or equal to 10 millimeters squared.

Claims

1. A temporary active fixation endocardial pacing lead having distal and proximal ends, comprising:

(a) a malleable, resilient lead body having a maximum diameter less than about 3.5 French and distal and proximal ends, the lead body comprising;

(i) coaxial inner and outer electrical conductors, the outer conductor having an outer surface, electrically insulative material being disposed between the conductors, the inner conductor comprising at least one wire, the outer conductor comprising a plurality of wires capable of transferring sufficient torque from the proximal end of the lead body to the distal end of the lead body to permit screwable affixation of the distal end of the lead in endocardial tissue;

(ii) an outer sheath formed of biocompatible and electrically insulative material, the sheath extending over and covering at least portions of the outer surface;

(b) first and second electrical connectors attached, respectively, to the proximal ends of the inner and outer electrical conductors;

(c) a helical screw-in retainer for active fixation in endocardial or myocardial tissue, the retainer being formed of biocompatible material, at least a portion of the retainer defining a tip electrode, the tip electrode being electrically and mechanically connected to the distal end of one of the inner and outer electrical conductors, the retainer having a diameter not exceeding about 4 French, the tip electrode having a surface area less than or equal to ten square millimeters;

(d) a ring electrode disposed between the retainer and the distal end of the lead body, the ring electrode being formed of biocompatible material and electrically connected to the distal end of the electrical conductor not attached to the retainer, the ratio of the surface area of the ring electrode to the surface area of the tip electrode being greater than or equal to 2;

1, and

(e) a malleable, resilient tube-shaped guide catheter having a maximum outside diameter not exceeding about 6 French and formed of biocompatible material, the guide catheter having distal and proximal ends and inner and outer surfaces, the guide catheter sheathing and extending over at least a portion of the lead body, the inner surface of the guide catheter having a diameter sufficient to accept the lead body therewithin.

2. The endocardial lead of claim 1, wherein a ten-inch long sample of the guide catheter is capable of transmitting at least about 0.10 ounce-inches of torque between its proximal and distal ends when the proximal end is held in a fixed position and the distal end is rotated through an angular displacement of 30 degrees.

3. The endocardial lead of claim 1, wherein a ten-inch long sample of the guide catheter is capable of transmitting at least about 0.20 ounce-inches of torque between its proximal and distal ends when the proximal end is held in a fixed position and the distal end is rotated through an angular displacement of 30 degrees.

4. The endocardial lead of claim 1, wherein a ten-inch long sample of the guide catheter is capable of transmitting at least about 0.40 ounce-inches of torque between its proximal and distal ends when the proximal end is held in a fixed position and the distal end is rotated through an angular displacement of 30 degrees.

5. The endocardial lead of claim 1, wherein a ten-inch long sample of the guide catheter is capable of transmitting at least about 0.20 ounce-inches of torque between its proximal and distal ends when the proximal end is held in a fixed position and the distal end is rotated through an angular displacement of 60 degrees.

6. The endocardial lead of claim 1, wherein a ten-inch long sample of the guide catheter is capable of transmitting at least about 0.40 ounce-inches of torque between its proximal and distal ends when the proximal end is held in a fixed position and the distal end is rotated through an angular displacement of 60 degrees.

7. The endocardial lead of claim 1, wherein a ten-inch long sample of the guide catheter is capable of transmitting at least about 0.60 ounce-inches of torque between its proximal and distal ends when the proximal end is held in a fixed position and the distal end is rotated through an angular displacement of 60 degrees.

8. The endocardial lead of claim 1, wherein a ten-inch long sample of the guide catheter is capable of transmitting at least about 0.80 ounce-inches of torque between its proximal and distal ends when the proximal end is held in a fixed position and the distal end is rotated through an angular displacement of 60 degrees.

9. The endocardial lead of claim 1, further comprising a hub having distal and proximal ends, the first end being attached to the proximal end of the guide catheter, the hub having a bore extending between its distal and proximal ends, the bore having a diameter sufficient to slidingly accept the lead body therewithin.

10. The endocardial lead of claim 9, further comprising a hemostasis valve attached to the proximal end of the hub, the valve having a first bore disposed therewithin, the first bore having a diameter sufficient to slidingly accept the lead body therewithin.

11. The endocardial lead of claim 10, wherein the hemostasis valve further has a second bore disposed therewithin, the first end of the second bore being contiguous with and intersecting at least an oblique angle the first bore, the second end of the second bore terminating in a neck attached to and extending outwardly from the outer surface of the valve.

12. The endocardial lead of claim 11, wherein the neck receives a sealing cap on the outer end thereof.

13. The endocardial lead of claim 1, wherein the connectors are pin connectors.

14. The endocardial lead of claim 13, wherein the pin connectors are arranged in staggered offset fashion respecting the lead body.

15. The endocardial lead of claim 1, wherein the ratio of ring electrode surface area to tip electrode surface area is greater than or equal to about 2.5:

1.

16. The endocardial lead of claim 1, wherein the ratio of ring electrode surface area to tip electrode surface area is greater than or equal to about 3:

1.

17. The endocardial lead of claim 1, wherein the ratio of ring electrode surface area to tip electrode surface area is greater than or equal to about 3.5:

1.

18. The endocardial lead of claim 1, wherein the ratio of ring electrode surface area to tip electrode surface area is greater than or equal to about 4:

1.

19. The endocardial lead of claim 1, wherein the ratio of ring electrode surface area to tip electrode surface area is greater than or equal to about 4.5:

1.

20. The endocardial lead of claim 1, wherein the ratio of ring electrode surface area to tip electrode surface area is greater than or equal to about 5:

1.

21. The endocardial lead of claim 1, wherein the tip electrode has a surface area less than or equal to about 9 mm².

22. The endocardial lead of claim 1, wherein the tip electrode has a surface area less than or equal to about 8 mm².

23. The endocardial lead of claim 1, wherein the tip electrode has a surface area less than or equal to about 7 mm².

24. The endocardial lead of claim 1, wherein the tip electrode has a surface area less than or equal to about 5 mm².

25. The endocardial lead of claim 1, wherein the tip electrode has a surface area less than or equal to about 3 mm².

26. The endocardial lead of claim 1, wherein a ten-inch long sample of the guide catheter is capable of transmitting at least about 0.30 ounce-inches of torque between its proximal and distal ends when the proximal end is held in a fixed position and the distal end is rotated through an angular displacement of 30 degrees.

27. A temporary endocardial pacing lead having distal and proximal ends, comprising:

(a) a malleable, resilient lead body having a maximum diameter less than about 3.5 French and distal and proximal ends, the lead body comprising;

(i) coaxial inner and outer means for conducting electricity, the outer conducting means having an outer surface, electrically insulative material being disposed between the conducting means, the inner conducting means comprising at least one wire, the outer conducting means comprising a plurality of wires capable of transferring sufficient torque from the proximal end of the lead body to the distal end of the lead body to permit screwable affixation of the distal end of the lead in endocardial tissue;

(ii) an outer sheathing means formed of biocompatible and electrically insulative material, the sheathing means extending over and covering at least portions of the outer surface;

(b) first and second electrical connecting means attached, respectively, to the proximal ends of the inner and outer electrical conducting means;

(c) active fixation means for active fixation in endocardial or myocardial tissue, the fixation means being formed of biocompatible material, at least a portion of the fixation means defining a tip electrode means, the tip electrode means being electrically and mechanically connected to the distal end of one of the inner and outer electrical conducting means, the fixation means having a diameter not exceeding about 4 French, the tip electrode having a surface area less than or equal to ten square millimeters;

(d) a ring electrode means disposed between the fixation means and the distal end of the lead body, the ring electrode means being formed of biocompatible material and electrically connected to the distal end of the electrical conducting means not attached to the fixation means, the ratio of the surface area of the ring electrode means to the surface area of the tip electrode means being greater than or equal to 2;

1, and

(e) a malleable, resilient tube-shaped guide catheter means having a maximum outside diameter not exceeding about 6 French and formed of biocompatible material, the guide catheter means having distal and proximal ends and inner and outer surfaces, the guide catheter means sheathing and extending over at least a portion of the lead body, the inner surface of the guide catheter means having a diameter sufficient to accept the lead body therewithin.

28. The endocardial lead of claim 27, further comprising a hub means having distal and proximal ends, the first end being attached to the proximal end of the guide catheter means, the hub means having a bore extending between its distal and proximal ends, the bore having a diameter sufficient to slidingly accept the lead body therewithin.

29. The endocardial lead of claim 28, further comprising a hemostasis valve means attached to the proximal end of the hub means, the valve means having a first bore disposed therewithin, the first bore having a diameter sufficient to slidingly accept the lead body therewithin.

30. The endocardial lead of claim 29, wherein the hemostasis valve means further has a second bore disposed therewithin, the first end of the second bore being contiguous with and intersecting at least an oblique angle the first bore, the second end of the second bore terminating in a neck attached to and extending outwardly from the outer surface of the valve means.

31. The endocardial lead of claim 30, wherein the neck receives a sealing cap means on the outer end thereof.

32. The endocardial lead of claim 27, wherein the connectors are pin connectors.

33. The endocardial lead of claim 32, wherein the pin connectors are arranged in staggered offset fashion respecting the lead body.

34. The endocardial lead of claim 27, wherein a ten-inch long sample of the guide catheter is capable of transmitting at least about 0.10 ounce-inches of torque between its proximal and distal ends when the proximal end is held in a fixed position and the distal end is rotated through an angular displacement of 30 degrees.

35. The endocardial lead of claim 27, wherein a ten-inch long sample of the guide catheter is capable of transmitting at least about 0.20 ounce-inches of torque between its proximal and distal ends when the proximal end is held in a fixed position and the distal end is rotated through an angular displacement of 30 degrees.

36. The endocardial lead of claim 27, wherein a ten-inch long sample of the guide catheter is capable of transmitting at least about 0.30 ounce-inches of torque between its proximal and distal ends when the proximal end is held in a fixed position and the distal end is rotated through an angular displacement of 30 degrees.

37. The endocardial lead of claim 27, wherein a ten-inch long sample of the guide catheter is capable of transmitting at least about 0.40 ounce-inches of torque between its proximal and distal ends when the proximal end is held in a fixed position and the distal end is rotated through an angular displacement of 30 degrees.

38. The endocardial lead of claim 27, wherein a ten-inch long sample of the guide catheter is capable of transmitting at least about 0.20 ounce-inches of torque between its proximal and distal ends when the proximal end is held in a fixed position and the distal end is rotated through an angular displacement of 60 degrees.

39. The endocardial lead of claim 27, wherein a ten-inch long sample of the guide catheter is capable of transmitting at least about 0.40 ounce-inches of torque between its proximal and distal ends when the proximal end is held in a fixed position and the distal end is rotated through an angular displacement of 60 degrees.

40. The endocardial lead of claim 27, wherein a ten-inch long sample of the guide catheter is capable of transmitting at least about 0.60 ounce-inches of torque between its proximal and distal ends when the proximal end is held in a fixed position and the distal end is rotated through an angular displacement of 60 degrees.

41. The endocardial lead of claim 27, wherein a ten-inch long sample of the guide catheter is capable of transmitting at least about 0.80 ounce-inches of torque between its proximal and distal ends when the proximal end is held in a fixed position and the distal end is rotated through an angular displacement of 60 degrees.

42. The endocardial lead of claim 27, wherein the ratio of ring electrode surface area to tip electrode surface area is greater than or equal to about 2.5:

1.

43. The endocardial lead of claim 27, wherein the ratio of ring electrode surface area to tip electrode surface area is greater than or equal to about 3:

1.

44. The endocardial lead of claim 27, wherein the ratio of ring electrode surface area to tip electrode surface area is greater than or equal to about 3.5:

1.

45. The endocardial lead of claim 27, wherein the ratio of ring electrode surface area to tip electrode surface area is greater than or equal to about 4.5:

1.

46. The endocardial lead of claim 27, wherein the ratio of ring electrode surface area to tip electrode surface area is greater than or equal to about 5:

1.

47. The endocardial lead of claim 27, wherein the tip electrode has a surface area less than or equal to about 9 mm².

48. The endocardial lead of claim 27, wherein the tip electrode has a surface area less than or equal to about 8 mm².

49. The endocardial lead of claim 27, wherein the tip electrode has a surface area less than or equal to about 7 mm².

50. The endocardial lead of claim 27, wherein the tip electrode has a surface area less than or equal to about 5 mm².

51. The endocardial lead of claim 27, wherein the tip electrode has a surface area less than or equal to about 3 mm².

52. The endocardial lead of claim 27, wherein the ratio of ring electrode surface area to tip electrode surface area is greater than or equal to about 4:

1.

53. A temporary active fixation endocardial pacing lead having distal and proximal ends, comprising:

(a) a malleable, resilient lead body having an outer surface defining a maximum diameter less than about 3.5 French, the lead body comprising distal and proximal ends, an outer sheath, and first and second electrical conductors, electrically insulative material being disposed between the conductors, the outer sheath formed of biocompatible and electrically insulative material, the sheath extending over and covering at least portions of the outer surface;

(b) first and second electrical connectors attached, respectively, to the proximal ends of the first and second electrical conductors;

(c) an active fixation device for active fixation in endocardial or myocardial tissue, the active fixation device being formed of biocompatible material, at least a portion of the active fixation device defining a tip electrode, the tip electrode being electrically and mechanically connected to the distal end of one of the first and second electrical conductors, the active fixation device having a diameter not exceeding about 4 French, the tip electrode having a surface area less than or equal to ten square millimeters;

(d) a ring electrode disposed between the active fixation device and the distal end of the lead body, the ring electrode being formed of biocompatible material and electrically connected to the distal end of the electrical conductor not attached to the active fixation device, the ratio of the surface area of the ring electrode to the surface area of the tip electrode being greater than or equal to 2;

1, and

(e) a malleable, resilient tube-shaped guide catheter having a maximum outside diameter not exceeding about 6 French and formed of biocompatible material, the guide catheter having distal and proximal ends and inner and outer surfaces, the guide catheter sheathing and extending over at least a portion of the lead body, the inner surface of the guide catheter having a diameter sufficient to accept the lead body therewithin.

54. The endocardial lead of claim 53, further comprising a hub means having distal and proximal ends, the first end being attached to the proximal end of the guide catheter means, the hub means having a bore extending between its distal and proximal ends, the bore having a diameter sufficient to slidingly accept the lead body therewithin.

55. The endocardial lead of claim 54, further comprising a hemostasis valve means attached to the proximal end of the hub means, the valve means having a first bore disposed therewithin, the first bore having a diameter sufficient to slidingly accept the lead body therewithin.

56. The endocardial lead of claim 55, wherein the hemostasis valve means further has a second bore disposed therewithin, the first end of the second bore being contiguous with and intersecting at least an oblique angle the first bore, the second end of the second bore terminating in a neck attached to and extending outwardly from the outer surface of the valve means.

57. The endocardial lead of claim 56, wherein the neck receives a sealing cap means on the outer end thereof.

58. The endocardial lead of claim 53, wherein the connectors are pin connectors.

59. The endocardial lead of claim 58, wherein the pin connectors are arranged in staggered offset fashion respecting the lead body.

60. The endocardial lead of claim 53, wherein a ten-inch long sample of the guide catheter is capable of transmitting at least about 0.10 ounce-inches of torque between its proximal and distal ends when the proximal end is held in a fixed position and the distal end is rotated through an angular displacement of 30 degrees.

61. The endocardial lead of claim 53, wherein a ten-inch long sample of the guide catheter is capable of transmitting at least about 0.20 ounce-inches of torque between its proximal and distal ends when the proximal end is held in a fixed position and the distal end is rotated through an angular displacement of 30 degrees.

62. The endocardial lead of claim 53, wherein a ten-inch long sample of the guide catheter is capable of transmitting at least about 0.30 ounce-inches of torque between its proximal and distal ends when the proximal end is held in a fixed position and the distal end is rotated through an angular displacement of 30 degrees.

63. The endocardial lead of claim 53, wherein a ten-inch long sample of the guide catheter is capable of transmitting at least about 0.40 ounce-inches of torque between its proximal and distal ends when the proximal end is held in a fixed position and the distal end is rotated through an angular displacement of 30 degrees.

64. The endocardial lead of claim 53, wherein a ten-inch long sample of the guide catheter is capable of transmitting at least about 0.20 ounce-inches of torque between its proximal and distal ends when the proximal end is held in a fixed position and the distal end is rotated through an angular displacement of 60 degrees.

65. The endocardial lead of claim 53, wherein a ten-inch long sample of the guide catheter is capable of transmitting at least about 0.40 ounce-inches of torque between its proximal and distal ends when the proximal end is held in a fixed position and the distal end is rotated through an angular displacement of 60 degrees.

66. The endocardial lead of claim 53, wherein a ten-inch long sample of the guide catheter is capable of transmitting at least about 0.60 ounce-inches of torque between its proximal and distal ends when the proximal end is held in a fixed position and the distal end is rotated through an angular displacement of 60 degrees.

67. The endocardial lead of claim 53, wherein a ten-inch long sample of the guide catheter is capable of transmitting at least about 0.80 ounce-inches of torque between its proximal and distal ends when the proximal end is held in a fixed position and the distal end is rotated through an angular displacement of 60 degrees.

68. The endocardial lead of claim 53, wherein the ratio of ring electrode surface area to tip electrode surface area is greater than or equal to about 2.5:

1.

69. The endocardial lead of claim 53, wherein the ratio of ring electrode surface area to tip electrode surface area is greater than or equal to about 3:

1.

70. The endocardial lead of claim 53, wherein the ratio of ring electrode surface area to tip electrode surface area is greater than or equal to about 3.5:

1.

71. The endocardial lead of claim 53, wherein the ratio of ring electrode surface area to tip electrode surface area is greater than or equal to about 4:

1.

72. The endocardial lead of claim 53, wherein the ratio of ring electrode surface area to tip electrode surface area is greater than or equal to about 4.5:

1.

73. The endocardial lead of claim 53, wherein the ratio of ring electrode surface area to tip electrode surface area is greater than or equal to about 5:

1.

74. The endocardial lead of claim 53, wherein the tip electrode has a surface area less than or equal to about 9 mm².

75. The endocardial lead of claim 53, wherein the tip electrode has a surface area less than or equal to about 8 mm².

76. The endocardial lead of claim 53, wherein the tip electrode has a surface area less than or equal to about 7 mm².

77. The endocardial lead of claim 53, wherein the tip electrode has a surface area less than or equal to about 5 mm².

78. The endocardial lead of claim 53, wherein the tip electrode has a surface area less than or equal to about 3 mm².

79. A temporary active fixation endocardial pacing lead having distal and proximal ends, comprising:

(a) a malleable, resilient lead body means having an outer surface defining a maximum diameter less than about 3.5 French, the lead body means comprising distal and proximal ends, an outer sheath, and first and second electrical conducting means, means for electrically insulating being disposed between the conducting means, the outer sheath formed of biocompatible and electrically insulative material, the sheath extending over and covering at least portions of the outer surface;

(b) first and second electrical connecting means attached, respectively, to the proximal ends of the first and second electrical conducting means;

(c) means for actively affixing to endocardial or myocardial tissue, the active fixation means being formed of biocompatible material, at least a portion of the active fixation means defining a tip electrode means, the tip electrode means being electrically and mechanically connected to the distal end of one of the first and second electrical conducting, the active fixation means having a diameter not exceeding about 4 French, the tip electrode means having a surface area less than or equal to ten square millimeters;

(d) a ring electrode means disposed between the active fixation means and the distal end of the lead body means, the ring electrode means being formed of biocompatible material and electrically connected to the distal end of the electrical conducting means not attached to the active fixation means, the ratio of the surface area of the ring electrode means to the surface area of the tip electrode means being greater than or equal to 2;

1, and

(e) a malleable, resilient tube-shaped guide catheter means having a maximum outside diameter not exceeding about 6 French and formed of biocompatible material, the guide catheter means having distal and proximal ends and inner and outer surfaces, the guide catheter means sheathing and extending over at least a portion of the lead body means, the inner surface of the guide catheter means having a diameter sufficient to accept the lead body means therewithin.

80. The endocardial lead of claim 79, further comprising a hub means having distal and proximal ends, the first end being attached to the proximal end of the guide catheter means, the hub means having a bore extending between its distal and proximal ends, the bore having a diameter sufficient to slidingly accept the lead body therewithin.

81. The endocardial lead of claim 80, further comprising a hemostasis valve means attached to the proximal end of the hub means, the valve means having a first bore disposed therewithin, the first bore having a diameter sufficient to slidingly accept the lead body means therewithin.

82. The endocardial lead of claim 81, wherein the hemostasis valve means further has a second bore disposed therewithin, the first end of the second bore being contiguous with and intersecting at least an oblique angle the first bore, the second end of the second bore terminating in a neck attached to and extending outwardly from the outer surface of the valve means.

83. The endocardial lead of claim 82, wherein the neck receives a sealing cap means on the outer end thereof.

84. The endocardial lead of claim 79, wherein the connectors are pin connectors.

85. The endocardial lead of claim 84, wherein the pin connectors are arranged in staggered offset fashion respecting the lead body.

86. The endocardial lead of claim 79, wherein a ten-inch long sample of the guide catheter is capable of transmitting at least about 0.10 ounce-inches of torque between its proximal and distal ends when the proximal end is held in a fixed position and the distal end is rotated through an angular displacement of 30 degrees.

87. The endocardial lead of claim 79, wherein a ten-inch long sample of the guide catheter is capable of transmitting at least about 0.20 ounce-inches of torque between its proximal and distal ends when the proximal end is held in a fixed position and the distal end is rotated through an angular displacement of 30 degrees.

88. The endocardial lead of claim 79, wherein a ten-inch long sample of the guide catheter is capable of transmitting at least about 0.30 ounce-inches of torque between its proximal and distal ends when the proximal end is held in a fixed position and the distal end is rotated through an angular displacement of 30 degrees.

89. The endocardial lead of claim 79, wherein a ten-inch long sample of the guide catheter is capable of transmitting at least about 0.40 ounce-inches of torque between its proximal and distal ends when the proximal end is held in a fixed position and the distal end is rotated through an angular displacement of 30 degrees.

90. The endocardial lead of claim 79, wherein a ten-inch long sample of the guide catheter is capable of transmitting at least about 0.20 ounce-inches of torque between its proximal and distal ends when the proximal end is held in a fixed position and the distal end is rotated through an angular displacement of 60 degrees.

91. The endocardial lead of claim 79, wherein a ten-inch long sample of the guide catheter is capable of transmitting at least about 0.40 ounce-inches of torque between its proximal and distal ends when the proximal end is held in a fixed position and the distal end is rotated through an angular displacement of 60 degrees.

92. The endocardial lead of claim 79, wherein a ten-inch long sample of the guide catheter is capable of transmitting at least about 0.60 ounce-inches of torque between its proximal and distal ends when the proximal end is held in a fixed position and the distal end is rotated through an angular displacement of 60 degrees.

93. The endocardial lead of claim 79, wherein a ten-inch long sample of the guide catheter is capable of transmitting at least about 0.80 ounce-inches of torque between its proximal and distal ends when the proximal end is held in a fixed position and the distal end is rotated through an angular displacement of 60 degrees.

94. The endocardial lead of claim 79, wherein the ratio of ring electrode surface area to tip electrode surface area is greater than or equal to about 2.5:

1.

95. The endocardial lead of claim 79, wherein the ratio of ring electrode surface area to tip electrode surface area is greater than or equal to about 3:

1.

96. The endocardial lead of claim 79, wherein the ratio of ring electrode surface area to tip electrode surface area is greater than or equal to about 3.5:

1.

97. The endocardial lead of claim 79, wherein the ratio of ring electrode surface area to tip electrode surface area is greater than or equal to about 4:

1.

98. The endocardial lead of claim 79, wherein the ratio of ring electrode surface area to tip electrode surface area is greater than or equal to about 4.5:

1.

99. The endocardial lead of claim 79, wherein the ratio of ring electrode surface area to tip electrode surface area is greater than or equal to about 5:

1.

100. The endocardial lead of claim 79, wherein the tip electrode has a surface area less than or equal to about 9 mm².

101. The endocardial lead of claim 79, wherein the tip electrode has a surface area less than or equal to about 8 mm².

102. The endocardial lead of claim 79, wherein the tip electrode has a surface area less than or equal to about 7 mm².

103. The endocardial lead of claim 79, wherein the tip electrode has a surface area less than or equal to about 5 mm².

104. The endocardial lead of claim 79, wherein the tip electrode has a surface area less than or equal to about 3 mm².

105. A temporary lead system, comprising:

(a) a lead body having proximal and distal ends, the outer diameter of the lead body not exceeding about 3.5 French, the lead body comprising at least first and second electrical conductors separated by electrically insulative material, a tip electrode disposed near the distal end of the lead body, a ring electrode disposed proximally of the tip electrode, and an active fixation device mechanically and electrically attached to the tip electrode, the tip electrode having a surface area less than or equal to ten square millimeters, the ratio of the surface area of the ring electrode to the surface area of the tip electrode exceeding about 2;

1, the tip electrode being mechanically and electrically connected to the first conductor, the ring electrode being mechanically and electrically connected to the second conductor, the lead body having first and second electrical connectors disposed at its proximal end, the first and second electrical connectors being mechanically and electrically connected to the first and second electrical conductors, respectively, and

(b) a guide catheter forming a resilient tube shape, having a maximum outside diameter not exceeding about 6 French and formed of biocompatible material, the guide catheter having distal and proximal ends and inner and outer surfaces, the guide catheter sheathing and extending over at least a portion of the lead body, the inner surface of the guide catheter having a diameter sufficient to accept the lead body therewithin,

wherein a ten-inch long sample of the guide catheter is capable off transmitting at least about 0.10 ounce-inches of torque between its proximal and distal ends when the proximal end is held in a fixed position and the distal end is rotated through an angular displacement of 30 degrees.

106. The endocardial lead of claim 105, wherein a ten-inch long sample of the guide catheter is capable of transmitting at least about 0.20 ounce-inches of torque between its proximal and distal ends when the proximal end is held in a fixed position and the distal end is rotated through an angular displacement of 30 degrees.

107. The endocardial lead of claim 105, wherein a ten-inch long sample of the guide catheter is capable of transmitting at least about 0.30 ounce-inches of torque between its proximal and distal ends when the proximal end is held in a fixed position and the distal end is rotated through an angular displacement of 30 degrees.

108. The endocardial lead of claim 105, wherein a ten-inch long sample of the guide catheter is capable of transmitting at least about 0.40 ounce-inches of torque between its proximal and distal ends when the proximal end is held in a fixed position and the distal end is rotated through an angular displacement of 30 degrees.

109. The endocardial lead of claim 105, wherein a ten-inch long sample of the guide catheter is capable of transmitting at least about 0.20 ounce-inches of torque between its proximal and distal ends when the proximal end is held in a fixed position and the distal end is rotated through an angular displacement of 60 degrees.

110. The endocardial lead of claim 105, wherein a ten-inch long sample of the guide catheter is capable of transmitting at least about 0.40 ounce-inches of torque between its proximal and distal ends when the proximal end is held in a fixed position and the distal end is rotated through an angular displacement of 60 degrees.

111. The endocardial lead of claim 105, wherein a ten-inch long sample of the guide catheter is capable of transmitting at least about 0.60 ounce-inches of torque between its proximal and distal ends when the proximal end is held in a fixed position and the distal end is rotated through an angular displacement of 60 degrees.

112. The endocardial lead of claim 105, wherein a ten-inch long sample of the guide catheter is capable of transmitting at least about 0.80 ounce-inches of torque between its proximal and distal ends when the proximal end is held in a fixed position and the distal end is rotated through an angular displacement of 60 degrees.

113. The endocardial lead of claim 105, wherein the ratio of ring electrode surface area to tip electrode surface area is greater than or equal to about 2.5:

1.

114. The endocardial lead of claim 105, wherein the ratio of ring electrode surface area to tip electrode surface area is greater than or equal to about 3:

1.

115. The endocardial lead of claim 105, wherein the ratio of ring electrode surface area to tip electrode surface area is greater than or equal to about 3.5:

1.

116. The endocardial lead of claim 105, wherein the ratio of ring electrode surface area to tip electrode surface area is greater than or equal to about 4:

1.

117. The endocardial lead of claim 105, wherein the ratio of ring electrode surface area to tip electrode surface area is greater than or equal to about 4.5:

1.

118. The endocardial lead of claim 105, wherein the ratio of ring electrode surface area to tip electrode surface area is greater than or equal to about 5:

1.

119. The endocardial lead of claim 105, wherein the tip electrode has a surface area less than or equal to about 9 mm².

120. The endocardial lead of claim 105, wherein the tip electrode has a surface area less than or equal to about 8 mm².

121. The endocardial lead of claim 105, wherein the tip electrode has a surface area less than or equal to about 7 mm².

122. The endocardial lead of claim 105, wherein the tip electrode has a surface area less than or equal to about 5 mm².

123. A method of making a temporary active fixation endocardial pacing lead having distal and proximal ends, comprising the steps of:

(a) providing a malleable, resilient lead body having an outer surface defining a maximum diameter less than about 3.5 French, the lead body comprising distal and proximal ends, an outer sheath, and first and second electrical conductors, electrically insulative material being disposed between the conductors, the outer sheath formed of biocompatible and electrically insulative material, the sheath extending over and covering at least portions of the outer surface;

(b) providing first and second electrical connectors attached, respectively, to the proximal ends of the first and second electrical conductors;

(c) providing an active fixation device for active fixation in endocardial or myocardial tissue, the active fixation device being formed of biocompatible material, at least a portion of the active fixation device defining a tip electrode, the tip electrode being electrically and mechanically connected to the distal end of one of the first and second electrical conductors, the active fixation device having a diameter not exceeding about 4 French, the tip electrode having a surface area less than or equal to ten square millimeters;

(d) providing a ring electrode disposed between the active fixation device and the distal end of the lead body, the ring electrode being formed of biocompatible material and electrically connected to the distal end of the electrical conductor not attached to the active fixation device, the ratio of the surface area of the ring electrode to the surface area of the tip electrode being greater than or equal to 2;

1, and

(e) providing a malleable, resilient tube-shaped guide catheter having a maximum outside diameter not exceeding about 6 French and formed of biocompatible material, the guide catheter having distal and proximal ends and inner and outer surfaces, the guide catheter sheathing and extending over at least a portion of the lead body, the inner surface of the guide catheter having a diameter sufficient to accept the lead body therewithin.