A lead assembly for intravenously conducting electrical signals through a venous path to or from a patient's heart, the lead assembly comprising in combination:
- (a) a core lead having first and second ends, said core lead including
- (i) first flexible sleeve means;
- (ii) a first conductor surrounded by material of said first flexible sleeve means, said first conductor extending approximately between the first and second ends of said core lead;
- (iii) first electrode means attached to said first flexible sleeve means approximately at the first end of said core lead, said first electrode means being electrically connected to said first conductor;
- (iv) a second conductor surrounded by material of said first flexible sleeve means, said second conductor being spaced from and electrically insulated from said first conductor, said second conductor extending approximately between the first and second ends of said core lead;
- (v) second electrode means attached to said first flexible sleeve means a first predetermined distance from said first electrode means, said second electrode means being electrically connected to said second conductor;
- (b) a first removable stylet extending through said first flexible sleeve means to facilitate control of said core lead, said core lead being preformed to tend to assume a straight configuration when said first stylet is removed from said core lead;
- (c) a channel lead having first and second ends, said channel lead including
- (i) second flexible sleeve means, said second flexible sleeve means having an elongated channel for receiving said core lead, said channel extending through a major portion of the length of said channel lead, said channel extending from a first opening in said channel lead to a second opening in said channel lead, said first opening being located at said first end of said channel lead, said second opening being a side port opening located a first predetermined distance from said second end of said channel lead;
- (ii) a third conductor surrounded by material of said second flexible sleeve means, said third conductor being disposed outside of said channel and extending approximately between the first and second ends of said second flexible sleeve means;
- (iii) third electrode means attached to said second flexible sleeve means approximately at the first end of said channel lead, said third electrode means being electrically connected to said second conductor;
- (iv) a fourth conductor surrounded by material of said second flexible sleeve means, said fourth conductor being disposed outside of said channel and extending approximately between the first and second ends of said second flexible sleeve means;
- (v) fourth electrode means attached to said second flexible sleeve means a second predetermined distance from said third electrode means;
- and
- (d) a second removable stylet extending through said second flexible sleeve means to facilitate control of said channel lead, said core lead being disposed in said channel lead, the first end of said core lead extending from said first opening and the second end of said core lead extending from said second opening, said first opening being located within the patient's heart when said channel lead is positioned to conduct the electrical signals to a predetermined portion of the patient's heart, said channel lead being preformed to tend to assume a bent configuration with a sufficient amount of bending located approximately at the location of said side port opening to cause said second end of said channel lead to move into a predetermined cavity in the patient's heart adjacent to said venous path when said second stylet is removed, said side port opening being located near the entrance to said predetermined cavity when the second end of said channel lead is in the deepest portion of said predetermined cavity, said core lead extending slidably through said side port opening deep into the right ventricle of the patient's heart.