Magnetic resonance imaging of patients with epicardial leads: in vitro evaluation of temperature changes at the lead tip

Purpose The aim of this study was to systematically investigate the potential heating effects of magnetic resonance imaging (MRI) in the presence of epicardial leads, which are connected to a device or abandoned, using a series of in vitro measurements. Methods The heating effects of MRI in a 1.5-T scanner were measured at the lead tip in a gel-filled tank. First, a transvenous lead (5086-45 cm, Medtronic) was compared with an epicardial lead (4968-35 cm, Medtronic) with and without connection to an MR-conditional pacemaker. Then, experiments were conducted using various lengths of epicardial leads exposed to MRI. Results (1) A temperature rise of + 2.5 degrees C was observed for the transvenous lead attached to an MRI-conditional pacemaker. The epicardial lead attached to the same pacemaker showed four times higher heating. (2) The transvenous lead without pacemaker showed four times higher heating, and the epicardial lead without pacemaker showed 30 times higher heating. (3) The epicardial lead coiled to 20 cm length without pacemaker showed 9 times higher heating. (4) Experiments with various lengths of epicardial leads showed that the shorter the leads were, the smaller was the heating effect. Conclusion Standard clinical MRI investigations may result in pronounced heating at the tip of epicardial electrodes. Epicardial leads, which are not connected to a pacemaker and thus mimicking abandoned leads, may even result in a more pronounced rise in temperature at the lead tip. Therefore, current epicardial pacing systems may carry a substantial risk of inducing thermal damage of the neighboring tissue during MRI scanning.