Three-year clinical experience with a new endocardial screw-in lead with introduction protection for use in the atrium and ventricle.

There is still a high incidence of dislodgement, threshold rises, and loss of sensing with permanent transvenous endocardial leads. Atrial leads are an even greater problem and require particularly reliable methods of fixation. In March, 1976 we reported our preliminary results from animal experiments using a new transvenous screw-in lead with introduction protection. This lead differs from other screw-in models as its spiral tip is retracted in the insulating tube during insertion. For fixation purposes a torque is applied to the proximal end of the conductor coil, which is loosely positioned within the tube, and this moves the helical electrode forward. One hundred and fifty endocardial electrodes have been implanted; 127 of them in the dilated ventricle and 23 in the atrium. The technique of introducing the lead into the vein (cephalic or jugular) was the same as that for conventional leads. It was easy to manage and quite uncomplicated. The fixation features in the atrium or the ventricle were sufficiently reliable to allow some patients to go home several hours post-implant. The total working time of the leads used has been 900 months; the overall complication rate is 2%.