Introduction: Wearable protectors are recommended for patients with cardiac implantable electronic devices (CIEDs) participating in sports to reduce associated risks. Their effectiveness has not been systematically evaluated. This study aimed to assess a custom-made protector in an in-vitro model of subcutaneous and submuscular CIEDs.
Methods: Ten CIEDs (five pacemakers, five implantable cardioverters/defibrillators (ICDs)) from all major manufacturers were implanted in an isolated porcine thorax in subcutaneous and submuscular positions. A custom-made chest protector (Sanitätshaus Glotz GmbH, Germany) was placed on top of the experimental setup. Controlled compressive forces were applied using a material testing machine (Instron, Illinois Tool Works Inc., USA), and transmitted forces were measured directly at the device surface with a pressure-sensitive film (IScan, TekScan Inc., USA). Both implantation sites were tested with and without protectors, and device functionality was assessed using an interactive heart simulator (Intersim III, IB Lang, Germany). In a second experimental setup, explanted CIEDs were exposed to progressively increasing forces until irreversible damage occurred.
Results: No functional abnormalities were observed in any CIED at forces up to 1000 N applied by the material testing machine. Higher forces reproducibly caused rib fractures in the porcine thorax. During experiments without a protector, the highest forces at the level of the CIEDs were observed with subcutaneous CIED placement (pacemakers: 277±3 N; ICDs: 412±11 N), followed by submuscular CIED placement (pacemakers: 241±1 N; ICDs: 229±3 N). For pacemakers, the use of a protector resulted in a 15-fold reduction of the mechanical force at the level of the pacemaker in subcutaneous position to 18±0.3 N (p<0.001) and a 30-fold reduction in submuscular position to 8±0.3 N (p<0.001). A similar trend was seen in ICDs with a 5-fold reduction of forces by the wearable chest protector to 75±2 N (p<0.001) in subcutaneously implanted ICDs and a 38-fold reduction of forces in submuscularly implanted ICDs to 6±0.4 N, (p<0.001).
In addition, explanted CIEDs covered by the wearable chest protector withstood forces up to 10.000 N without irreversible damage, whereas all unprotected devices failed at this load.
Conclusion: A wearable protector provides substantial mechanical protection for CIEDs in an in-vitro animal model. The protector markedly reduced forces demonstrating effective mitigation of damage in collisions comparable to recreational sports. Thus, the risk of mechanical damage of CIEDs in the presence of a protector seems to be very low for most sports activities.
