Kee-Joon Choi, MD Division of Cardiology, Department of Internal Medicine, Asan Medical Center, Ulsan University School of Medicine, Seoul, Korea Troubleshooting ICD therapy ABSTRACT Implantable cardioverter-defibrillator (ICD) is implanted in patients who have potentially fatal tachyarrhythmia. Appropriate ICD therapy reduces the risk of death from fatal tachyarrhythmia in patients with high risk of sudden death. ICD is programmed to detect and respond to specific criteria indicative of ventricular fibrillation (VF) or ventricular tachycardia (VT). The major problem in patients with ICD is to determine the most appropriate programme settings for ensuring reliable functioning and to prevent inappropriate shock. ICD troubleshooting is occasionally required because of inappropriate ICD sensing or shock application or because patients who require appropriate ICD therapy fail to receive it. In such cases, the reasons for the inappropriate ICD responses are analyzed and the programmed settings changed if required, or other changes are made to ensure the problem is resolved. With the recent progresses in ICD technology, this technology now has many varied and complex characteristics; therefore, troubleshooting ICD therapy has become a much more complicated and challenging task. Extensive knowledge of the different features and algorithms of ICD is now essential. This review summarizes ICD troubleshooting that we have encountered during ICD follow-up. Key words: Implantable cardioverter-defibrillator (ICD) ventricular tachycardia ventricular fibrillation Received: November 28, 2011 Accepted: March 30, 2012 Correspondence: Kee-Joon Choi, MD, Professor, Division of Cardiology, Department of Internal Medicine, Asan Medical Center, Ulsan University School of Medicine, 388-1, Poongnap-dong, Song-pa-gu, Seoul, Korea, 138-736 Tel: 82-2-3010-3167, Fax: 82-2-487-5918, E-mail: kjchoi@amc.seoul.kr 23

Figure 1. Schematic representation of the possible causes of shock delivery. Shocks can be delivered either because of tachycardia (ventricular and appropriate or supraventricular and inappropriate) or because of oversensing problems (all inappropriate). SVT; supraventricular tachycardia, VF; ventricular fibrillation, VT; ventricular tachycardia 24 The Official Journal of Korean Heart Rhythm Society

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A B Figure 2. (A) T-wave oversensing. Inappropriate T-wave oversensing confirmed by intracardiac electrogram. (B) Inappropriate shock. VF detection and inappropriate shock of 676 V (25 J). Figure 3. Decay Delay and Threshold Start. Resetting of the sensing-related program, Decay Delay and Threshold Start. 27

A B Figure 4. Decay Delay (A) and Threshold Start (B). References 1. Van EL, Schalij MJ. Troubleshooting implantable cardioverterdefibrillator related problems. Heart. 2008;94:649-660. 2. James PD, Wojciech Z, David SC, Scott M, Spencer ZR, Paul W, Claudio S, Jonathan SS, Steven LH, David JW, Helmut K, Mark LA, W. Jackson H, Arthur JM for the MADIT II Investigators. Inappropriate Implantable Cardioverter-Defibrillator Shocks in MADIT II. J Am Coll Cardiol. 2008;51:1357-1365. 3. Schreieck J, Zrenner B, Kolb C, Ndrepepa G, Schmitt C. Inappropriate shock delivery due to ventricular double detection with a biventricular pacing implantable cardioverter defibrillator. 28 The Official Journal of Korean Heart Rhythm Society

Pacing Clin Electrophysiol. 2001;24:1154-1157. 4. Hiroshi W, Masaomi C, Daisuke I, Akinori S, Shinsuke O, Kazuki O, Satoru K, Yukio H, Hiroshi F, Takashi W, Yoshifusa A. Decrease in Amplitude of Intracardiac Ventricular Electrogram and Inappropriate Therapy in Patients With an Implantable Cardioverter Defibrillator. Int Heart J. 2006;47:363-370. 5. Christof K, Bernhard Z, Claus S. Incidence of Electromagnetic Interference in Implantable Cardioverter Defibrillators. Pacing Clin Electrophysiol. 2001;24: 465-468. 6. William HM, Megan M, Bram DZ, Thomas PG, Oscar HT, Donna- Bea T, Daniel BS. Pacemaker and ICD Generator Malfunctions Analysis of Food and Drug Administration Annual Reports. JAMA. 2006;295:1901-1906 7. Hauser RG, Hayes DL. Increasing hazard of Sprint Fidelis implantable cardioverter-defibrillator lead failure. Heart Rhythm. 2009;6:605-610. 8. AE Epstein, KA Ellenbogen, KA Kirk, GN Kay, SM Dailey and VJ Plumb. Clinical characteristics and outcome of patients with high defibrillation thresholds. A multicenter study. Circulation. 1992;86:1206-1216 9. David LH, Paul AF. Cardiac Pacing, Defibrillation and Resynchronization: A Clinical Approach. 2006:445-510. 10. Diemberger I, Martignani C, Biffi M, Frabetti L, Valzania C, Cooke RM, Rapezzi C, Branzi A, Boriani G. Arrhythmia discrimination by physician and defibrillator: Importance of atrial channel. Int J Cardiol. 2010. [Epub ahead of print] 29