Effects of blunt force trauma on cardiac implantable electronic devices

Introduction: Patients with cardiac implantable electronic devices are routinely advised against physical activity with a risk of collision because of expected damage to the implanted device. However, despite corresponding guideline recommendations no data support this practice. The aim of this study was therefore to evaluate the effect of blunt force trauma on CIED in an experimental porcine model.

Methods: Sixteen CIED (6 pacemakers, 5 ICD, 5 CRT) from all manufacturers were connected to respective leads and implanted subcutaneously in an isolated section of a porcine thorax. Afterwards, increasing weights were dropped on the experimental setting. Resulting forces were measured by a force plate below the ribs. After each impact, CIED function was analyzed by connecting the device to an interactive heart simulator (InterSim III, IB Lang). Subsequently, subcutaneous and submuscular device placements were compared in a material testing machine (Z005, Zwick/Roell).

Results: None of the pacemakers, ICD or CRT showed signs of permanent device malfunction when tested up to forces of 2000N. Forces exceeding 1500N reproducibly lead to rib fractures of the porcine thorax, in line with previous reports describing serial rib fractures in humans at similar forces. One IS1/DF1 single-coil ICD lead was bent close to the connector after an impact of 900N on the experimental setting, however no signs of lead malfunction were noted on inspection and fluoroscopy. Measured forces at the level of the CIED in the material testing machine were halved when a submuscular placement was chosen as compared to a subcutaneous placement. In a subsequent experiment without a porcine thorax, modes of device failure when exposed to increasing forces were elucidated. When testing a representative selection of 9 CIED to failure, 3 CIED showed complete dysfunction and were unable to be interrogated after impact, 3 CIED displayed an exit block, 1 CIED had reduced sensing values and 1 pacemaker entered safety mode. Furthermore, 1 CRT-D was unable to terminate VF despite reporting normal shock impedances before VF induction. While all 9 CIED showed signs of damage on visual inspection, only 2 CIED showed signs of damage on fluoroscopy.

Conclusion: This is the first study to analyze the effects of blunt-force trauma on cardiac implantable electronic devices. Our data suggest (1) that subcutaneously implanted CIED withstand physical forces which would result in serial rib fractures in humans, (2) that submuscular device placement furthermore reduces the risk of CIED damage, and (3) that if damage to a CIED system should occur, it can manifest as damage to the device generator, damage to the connection between generator and header or as damage to the lead. Therefore, general traumatological risks possibly outweigh the risks of CIED damage in sports with a low likelihood of collision.