Assessment of Novel Implant Technique for Cardiac Monitors

Background: Insertable cardiac monitors (ICM) allow for continuous monitoring of symptom- rhythm correlation, particularly in cases of infrequent and unpredictable symptoms. It is currently recommended that ICMs be implanted in a diagonal direction on the left anterior chest. Skin tenting and device erosion may occur in smaller children following this technique. We devised a vertical implantation technique, lateral to the sternum to avoid this issue. The purpose of this study was to assess the safety and efficacy vertical device (V) compared to control horizontal (H) implantation.

Methods: Single center, IRB approved retrospective study of pediatric patients that underwent device implantation from 2017-2021. All device implants were performed under sterile conditions in the electrophysiology laboratory after informed consent. The ICM was inserted subcutaneously following the recommendations provided by the companies. R-waves were detected by the ICM using a pre-programmed algorithm and manually confirmed. The presence of P-waves at implant were confirmed manually by pediatric electrophysiologist. Data collected included demographics, implant orientation (H or V), complications, device type, presence of P wave, and measurement of R-wave amplitude at both implantation, as well as follow up.

Results: ICMs were implanted in 28 patients without congenital heart disease. Fifty percent (14) of the cohort were V implantation. All patients in both groups had detectable P waves at the time of implant. Initial R wave amplitude average for V was 1.05, H was 0.99 (p=NS). Follow-up R-wave amplitude V was 1.03 and H was 0.93 (p=NS). Mean age for V was 12.5 years and H was 11.5 year (p=NS). V group had 79% males (11), while H group was 50% male (7). There was no significant difference in body surface area at the time of implantation for V (1.22) and H groups (1.29) . There was a median follow up period of 9-months for V and 20-months for H (p=NS). There were no complications experienced in either group.

Conclusion: Vertical ICM implantation is a safe and effective novel surgical technique. Long-term follow up demonstrates non-inferior R wave detection and no significant signal deterioration, when compared to controls.