Cardiac pacemaker leads--a radiographic perspective

To comment on the adequacy of positioning of single- or dual-chambered pacemaker leads requires some knowledge of the type of electrode used. Earlier leads relied upon force transmitted along the body of the lead to the electrode-myocardial interface to maintain positioning. These relatively large stiff leads were placed almost exclusively near the apex of the right ventricle to prevent dislodgement. More recent leads incorporate mechanical fixation devices to maintain position, commonly either tined or screw-in electrodes (or variations of these) representing passive and active fixation mechanisms respectively. The tines are not radiopaque; the screw-in devices are metallic. Such newer electrodes permit the use of smaller, more flexible leads, reduce the necessity for precise positioning, and reduce the frequency of lead dislodgement.