Atrioventricular pacing/sensing lead

Claim 1

l.An atrioventricular lead having a distal end portion and comprising a tubing of flexible elastomeric insulating material having a distal end, a tip electrode mounted at the distal end of said tubing, a first insulated coiled conductor received within said tubing and having a distal end extending to and being electrically connected to said tip electrode, at least one ring electrode around said tubing spaced rearwardly of said tip electrode, at least one second insulated coiled conductor received within said tubing, surrounding said first insulated coiled conductor and having a distal end which terminates adjacent to, and which is connected to, said ring electrode and an elongate rod situated within said distal end portion of said lead between said tubing and said second coiled conductor, said rod having a middle portion situated in the area of said ring electrode, a proximal end portion and a distal end portion, said distal end portion of said rod extending toward but not to the location of said tip electrode, said elongate rod being made of a titanium nickel alloy which has a mechanical memory that is triggered by heat, being initially formed with an original shape approaching that of a bell-shaped distribution curve and being annealed in that form and then subsequently reformed to a straight shape which said rod has when it is mounted within said distal end portion of said lead for facilitating insertion of said lead distal end portion into an atrium and a ventricle of a heart whereby after insertion of said tip electrode of said lead into the ventricle, said rod in the area of said ring electrode can be heated to cause said elongate rod to return to its original bell-shaped distribution curve shape to force said at least one ring electrode against the atrial wall such as for sensing while said tip electrode engages the bottom wall, e.g., apex, of the ventricle such as for pacing.