The small-tined pacemaker lead--absence of dislodgement

The Medtronic 6961 unipolar transvenous ventricular lead has four symmetrically placed, small tines that protrude backward just proximal to the tip, and are designed to become entrapped beneath or between right ventricular trabeculae. One hundred leads were implanted. Initially, the leads were more difficult to position at the right ventricular apex as the tines tended to anchor on intracardiac structures. This was overcome by rotating the lead. The time of negotiating the lead from right atrium to right ventricular apex averaged 3.1 minutes for all leads. The first 20 procedures averaged 4.2 minutes and the last 20 averaged 2.1 minutes. In this latter group, 11 of the 20 passages took 60 seconds or less. Once adequate positioning was obtained, the lead was retracted using slight tension to demonstrate tip entrapment. There were no lead dislodgements. Eight deaths occurred following institution of pacing and lead dislodgement was not detected in any of these cases. Four patients had complications associated with pacing, two transient diaphragmatic pacing not requiring reoperation, one right ventricular perforation and one raised threshold with intermittent failure of pacing without lead perforation or dislodgement. Because of the absence of dislodgement, this lead appears to have significant advantages over conventional leads.