Europace Advance Access originally published online on April 4, 2008
Europace 2008 10(6):738-740; doi:10.1093/europace/eun095
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ICDs
Automatic R-wave and impedance testing with the modern patient alert system to reduce inappropriate implantable cardioverter defibrillator shocks due to lead fracture
1 School of Health Science, Niigata University School of Medicine, 2-746 Asahimachi, Chuou-ku, Niigata 951-8518, Japan; 2 First Department of Internal Medicine, Niigata University School of Medicine, Niigata 951-8518, Japan
Manuscript submitted 22 January 2008. Accepted after revision 24 March 2008.
* Corresponding author. Tel: +81 25 227 2185; fax: +81 25 227 0774. E-mail address: masaomi{at}clg.niigata-u.ac.jp
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A 62-year-old man was afflicted with implantable cardioverter defibrillator (ICD) shocks during sinus rhythm. Stored ICD data revealed that sensing of noise due to fracture of the ventricular lead triggered the delivery of shocks. Since the lead fracture developed suddenly, it is suggested that close, early attention should be paid to the potential of such events during follow-up of ICD leads.
We recently examined a patient treated by an implantable cardioverter defibrillator (ICD) who had received multiple shocks triggered by the noise resulting from a fracture of the ventricular lead. Similar cases have been reported in a series of ICD lead studies in North America without detailed description of the patients' clinical outcome.
A 62-year-old man with a history of myocardial infarction was admitted to our hospital for management of repetitive ICD discharges. In June 2006, ventricular tachycardia developed, and a MaximoTM DR dual-chamber pulse generator (Medtronic Inc., Minneapolis, MN, USA) was implanted, connected to model 6949-58 and 5076-45 right ventricular (RV) and right atrium (RA) leads (Medtronic), respectively. During the implantation procedure, both leads were implanted using an extrathoracic puncture technique. At implant, the R-wave amplitude was 10.2 mV, RV capture threshold 0.8 V/0.5 ms, and RV lead impedance 568 
(Figure 1). The P-wave amplitude was 1.8 mV, RA capture threshold 2.1 V/0.5 ms, and RA lead impedance 408 . Ventricular fibrillation (VF), induced by T-wave shock, was twice successfully terminated by 25 J shocks from the ICD.
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After discharge, the patient was scheduled to return to our ambulatory ICD clinic every 3 months. He remained clinically stable and initially free from ICD shocks. However, 16 months after implantation, he began experiencing ICD discharges. Retrieval of the stored ICD data revealed that sensing of noise had caused the ICD to discharge (Figure 2), and that the VF criteria had been satisfied 12 times, with a total of four shocks delivered during sinus rhythm. In addition, 6 weeks prior to examination, episodes of self-limiting VF have also been detected with increasing frequency. Compared with the values obtained at the last ambulatory visit, the R-wave amplitude had decreased from 11.0 to 2.1 mV and ventricular pacing lead impedance had increased from 480 to >3000
(Figure 1), whereas the RV and superior vena cava shock coil impedance had remained nearly unchanged. In addition, the P-wave amplitude and atrial pacing impedance were within the normal ranges. Neither the ventricular nor the atrial lead appeared abnormal on the chest roentgenogram. We extracted the ventricular lead and explanted the pulse generator. No abnormality was observed on the surface insulation of the extracted lead.
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Oversensing is one of the complications for ICD recipients and can be life-threatening when shocks are delivered during sinus rhythm in the ventricular vulnerable period.1
–3 Lead fracture is sometimes a complication of the implant procedure. However, it was unlikely in our patient since: (i) the atrial and ventricular leads were inserted using an extrathoracic puncture technique and (ii) no abnormality was observed on the chest roentgenogram or on the surface insulation of the extracted ventricular lead. In this patient, the stored ICD data indicated that the lead fracture had occurred suddenly and was thus a complication that could not be predicted at the time of the scheduled clinic visits. The following signs are suggested to be helpful in the detection of dysfunctions of ventricular ICD leads: (i) an increasing count on the Sensing Integrity CounterTM of the lead status report; (ii) episodes of non-sustained VF with short R-R intervals; and (iii) an abrupt increase in lead impedance.4 Furthermore, automatic R-wave and impedance testing may detect this problem much more easily, most likely before any inappropriate shock, and these could have been a warning to the patient equipped with a modern patient alert system. The programming of a nominal or greater number of cycles in the VF detection counter, coupled with more frequent ICD clinic visits, is potentially an effective way to minimize the risk of inappropriate ICD discharge caused by lead dysfunction. Conflict of interest: none declared.
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[1] Rauwolf T, Guenther M, Hass N, Schnabel A, Bock M, Braun MU, et al. Ventricular oversensing in 518 patients with implanted cardiac defibrillators: incidence, complications and solution. Europace (2007) 9:1041–7.
[2] Kleemann T, Becker T, Doenges K, Vater M, Senges J, Schneider S, et al. Annual rate of transvenous defibrillation lead defects in implantable cardioverter-defibrillator over a period of >10 years. Circulation (2007) 115:2474–80.
[3] Kitamura S, Satomi K, Kurita T, Shimizu W, Suyama K, Aihara N, Long-term follow-up of transvenous defibrillation leads., et al. High incidence of fracture in coaxial polyurethane lead. Circ J (2006) 70:273–7.[CrossRef][Web of Science][Medline]
[4] Ellenbogen KA, Wood MA, Shepard RK, Clemo HF, Vaughn T, Holloman K, et al. Detection and management of an implantable cardiac defibrillator lead failure. J Am Coll Cardiol (2003) 41:73–80.
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