Cardiovascular Implantable Electronic Devices -> Diagnostic Devices & Sensors: -> Clinical Trials D-PO03 - Poster Session III (ID 48) Poster

D-PO03-086 - Mechanism Of Sensing Delay Possibly Occurring During Intraoperative Defibrillation Test In Subcutaneous Implantable Cardioverter-defibrillator (ID 1099)


Background: We previously reported that in patients undergoing implantation of subcutaneous implantable cardioverter-defibrillator (S-ICD), sensing delay from detection of ventricular fibrillation (VF) to shock therapy occurred in 16% of the patients during intraoperative defibrillation test (DFT). The precise mechanism of this sensing delay in DFT for S-ICD remains to be elucidated.
Objective: To clarify the mechanism of sensing delay by analyzing the sensing algorism and amplitude of induced VF
Methods: We investigated 39 patients in whom DFT was successfully performed at S-ICD implantation. The patients were divided into 2 groups by the time duration from the first detection of VF to shock therapy: No-delay group with time to therapy < or =18 seconds and Delay group >18 seconds. The mean amplitude of induced VF, numbers of “Slow (S)” and “Tachycardia (T)” markers and two components of the sensing duration from the first detection of VF to the beginning of the charge and from the charge to shock deliver were compared between the 2 groups.
Results: There were 6 in Delay and 33 in No-delay group, and times to therapy were 21.5±3.1 and 14.2±1.2 seconds, respectively. Of the components of time to therapy, the interval from the first detection of VF to the beginning of charge was significantly longer in Delay than in No-delay group (14.6±3.2 versus 7.7±1.2 second, p<0.001), while the interval from the beginning of charge to shock deliver was similar. In the time from VF sensing to charge, the number of “S” marker was significantly higher in Delay than in Non-delay group (14±2.1 versus 2.9±3.0, p < 0.001). The number of “T” marker was similar between the 2 groups. When looking at induced VF, the mean VF amplitude (mV) was not different (0.94±0.3 in No-delay versus 0.89±0.5 in Delay group, p= 0.73).
Conclusion: Sensing delay for VF therapy mainly occurs due to the delay in conversion from “S” to “T” zone. Once S-ICD sensing mode shifts to “T” zone, sensing delay does not occur even if VF amplitude is low, indicating a reliable sensing system of S-ICD.