Abstract: Cardiac resynchronization therapy (CRT) is biventricular pacing in which one lead paces the right ventricle endocardialy, another the left ventricle epicardially through a coronary vein and a third paces the right atrial appendage. It is a mode of treatment of left ventricular failure due to cardiac dyssynchrony, usually with left bundle branch block and wide QRS complex.
Pulse generator is seen in the left infraclavicular region with three leads connected. One lead is seen free behind the pulse generator, possibly an earlier right ventricular lead which has been abandoned. It may be noted that an abandoned lead of special interest in consideration of potential magnetic resonance imaging.1 Abandoned pacing leads show resonant heating with greater lead tip heating than leads connected to a pulse generator. The lead with J shaped tip has its tip located in the right atrial appendage for atrial pacing. Right ventricle shows two bipolar leads side by side near the left hemidiaphragm, one being an old abandoned ventricular lead and another an active right ventricular lead. The left ventricular leading going through the coronary sinus to settle in coronary vein with two electrodes at higher inter electrode distance is better seen the picture below. The atrial electrode tip shows a screw suggesting that it is a screw in lead than a tined lead. Ventricular lead tips are suggestive of tined leads with no screw visible.
Langman DA, Goldberg IB, Finn JP, Ennis DB. Pacemaker lead tip heating in abandoned and pacemaker-attached leads at 1.5 tesla mri. J Magn Reson Imaging 2011, 33:426-31.