T Wave Safety Margin during the Process of ICD Implantation As a Novel Predictor of T Wave Oversensing

Figures

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  Figure 1. (A) Ex vivo ICD connection during the procedure of ICD implantation using the active-fixation lead. (B) TWSM measurements. The green line indicates the sensing threshold curve of ICD. (C) The timeline for the evaluation of TWSM.

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  Figure 2. Bland-Altman analysis comparing R wave amplitudes measured from implantable cardioverter-defibrillator printouts. (A) Measurement of R wave amplitude by Fortify ICD. Noted that IEGM of ICD automatically switched to “Ventricular amplifier” channel to measure R wave amplitude. (B,C) R wave amplitude measured from by Fortify ICD. (D,E) R wave amplitude measured by Virtuoso ICD. Inner dashed line is the mean difference; outer dashed lines are mean ± 1.96 SD.

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  Figure 3. Comparison of R wave amplitude, T wave amplitudes and TWSMs by different ICDs. (A). R wave amplitudes by different ICDs; (B,C) T wave amplitudes post sensing intrinsic rhythm and post pacing at 90/min in Fortify and Teligen ICDs. (D) TWSM after sensing intrinsic rhythm and pacing in Fortify and Teligen. Red line indicates safety margin of 2 (200%). *P < 0.05; **P < 0.01.

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  Figure 4. TWOS episodes during the procedure of ICD implantation and sensing threshold curves with real proportion. (A) 12-lead surface electrocardiogram of the short QT syndrome patient. (B) TWOS under the maximum sensitivity in Virtuoso ICD. Red line shows the blank period after sensing; green line shows the sensing curve with minimum sensitivity; blue lines show sensing curves with sensitivity of 0.3 and 0.15 mV; red dot shows the possible range of T wave amplitudes. (C) Intermittent TWOS under maximum sensitivity in Epic ICD. Green and blue lines show the sensing curves with minimum and default sensitivity, respectively. (D) Measurement of TWSM in Fortify ICD. (E,F) Measurement of TWSM in Vitality and Teligen ICDs. Blue lines show the sensing curve with default sensitivity.

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  Figure 5. Post pacing TWOS revealed during the procedure of ICD implantation in Brugada syndrome patient, hypertrophic cardiomyopathy patient and dialated cardiomyopathy patient. (A) 12-lead surface EKG of a Brugada syndrome patient. (B,C) Post pacing TWOS episodes by a Consulta ICD under sensitivity of 0.15 mV. No TWOS was recorded under 0.3 mV. (D) 12-lead surface EKG of a hypertrophic cardiomyopathy patient. The implantable cardioverter-defibrillator working mode is VAT. (E) Post pacing TWOS episodes in Virtuoso ICD under the sensitivity of 0.15 mV. (F) 12-lead EKG of a CRT-D patient with dilated cardiomyopathy. (G) After the episode of TWOS (①), PVARP was prolonged by PVC response and sinus P wave was recognized as a premature beat (②) and not traced by ventricle (③).