|
|
||||||||||
|
J Am Coll Cardiol, 2003; 41:73-80 © 2003 by the American College of Cardiology Foundation |





* Division of Cardiology, Medical College of Virginia/Virginia Commonwealth University, Richmond, Virginia, USA
Medtronic, Inc., Minneapolis, Minnesota, USA
Manuscript received May 6, 2002; revised manuscript received August 6, 2002, accepted August 19, 2002.
* Reprint requests and correspondence: Dr. Kenneth A. Ellenbogen, Medical College of Virginia, P.O. Box 980053, Richmond, Virginia 23398-0053, USA.
kellenbogen{at}pol.net
| Abstract |
|---|
|
|
|---|
BACKGROUND: Despite recent advances in ICD technology, the long-term reliability of ICD leads remains a significant problem.
METHODS: Concern about long-term reliability of coaxial polyurethane ICD leads caused us to systematically study all patients implanted with Medtronic (Minneapolis, Minnesota) 6936 lead at our institution. We performed follow-up of 74 patients with 76 ICD leads that were implanted from February 28, 1995 to September 8, 1997. Thirty-seven patients underwent routine clinical ICD follow-up testing and ventricular fibrillation induction to determine the status of their ICD lead after a mean follow-up of 68.6 ± 8.2 months.
RESULTS: The lead survival analysis shows a cumulative failure probability of 37% (confidence interval, 24% to 54%) at 68.6 months. Six patients demonstrated a previously undescribed mode of ICD lead failure: prolonged oversensing immediately after shock therapy. The use of short interval counters to monitor nonphysiologic R-R intervals and the measurement of ring-to-coil impedance detected early lead failures in five patients.
CONCLUSIONS: This analysis shows: 1) problems with ICD leads may not become apparent until late during follow-up and may become a significant late problem, 2) a "signature" mode of lead failure for the 6936 consisting of oversensing of electrical noise following shocks, 3) early detection of lead failure with a short interval counter algorithm or measurement of ring-to-coil impedance may be clinically useful.
| ||||||||||
Implantable cardioverter defibrillator lead dysfunction may result in failure of the ICD to deliver therapy for ventricular tachycardia and, thus, result in syncope or sudden death. Lead dysfunction may also result in inappropriate shocks and subsequent psychological distress, need for operative revision or removal resulting in additional morbidity and mortality, and increased health care costs. Implantable cardioverter defibrillator lead failure may initially be clinically silent, and early detection before clinical presentation with inappropriate shocks or sudden death is important. Patients with ICD leads demonstrating an increased failure rate also need closer follow-up. Finally, lessons learned from ICD leads with high failure rates may help engineers design better and more reliable leads.
We noted a unique mode of failure of an ICD lead during clinical follow-up that led us to perform a systematic evaluation of all patients at our institution with this lead. The purpose of this investigation was to determine the mode, incidence, and time course of failure of patients with the Medtronic 6936 ICD lead. Finally, we sought to determine if any electrophysiologic measurements could predict the development of lead failure.
| Methods |
|---|
|
|
|---|
|
. In an integrated bipolar lead, where the ring is the coil, the normal measurement is approximately 4
. In theory, as the inner insulation fails on a bipolar ICD lead, the ring-to-coil impedance is expected to fall. Patients who moved out of state had all follow-ups done by their local electrophysiologist except for ventricular fibrillation induction, and the results were forwarded to one of the investigators for review. All patients who were deceased had their medical records reviewed and their family and local doctors contacted to obtain details about the events at the time of death.
Oversensing was defined as the detection of inappropriate electrical signals by the pulse generators sense amplifier. Undersensing was defined as the failure to sense a signal visible on the surface electrocardiogram. Metal ion oxidation (MIO) was defined when examination of the pacing leads by the manufacturer confirmed this. Returned product analysis consists of electrical testing to determine the continuity of the conductor coils, and microscopic examination to assess the presence of insulation breaching. Metal ion oxidation is a type of insulation failure that occurs with polyurethane leads caused by degradation of the polyurethane on the inside of the lead initiated by the migration of ions from the conductor wire.
Statistics. All variables were reported as mean ± SD. Kaplan-Meier product limit method was used to compute survival estimates of chronic lead performance of the 6936 leads. The Greenwood method was used to compute the 95% confidence interval (CI) for survival at each failure time of the leads. The log-rank method was used to compare the 6936 lead survival curves for different vein access methods. Continuous variables between groups were compared using the t test.
| Results |
|---|
|
|
|---|
Clinical follow-up.
From May 1995 to July 2001, all ICD patients underwent routine follow-up. During this period of time, ICD lead failures were detected in 14 patients. The failure mechanism(s) detected in these patients are shown in Figure 2. Of the 14 patients who had evidence of ICD lead failure, six patients presented with postshock oversensing, one patient presented with noise on the rate/sensing electrogram during sinus rhythm, one patient presented with high pacing impedance, two patients presented with high shocking impedance, one patient presented with poor sensing of R waves during sinus rhythm, one patient presented with low pacing impedance (<200
), and two patients presented with abnormal impedances for both the rate/sensing and high-voltage measurements. Four additional patients had their leads removed because of infection or heart transplantation.
|
|
|
|
Three additional failures were detected by routine clinical follow-up. In these patients short interval counters and/or ring-to-coil impedance measurements predicted lead failure (Fig. 5). One patient had a short interval counter >2,400 and a decrease in ring-to-coil impedance from 30 to 9
in the period five months before the time of ICD testing. One month later the short interval counter was >10,000, and a decrease in coil-to-tip impedance was noted. One episode of oversensing was noted, but no therapy was delivered.
|
. No episodes of ventricular tachycardia were detected. This patient underwent ICD lead extraction. One patient had normal ICD testing, but one week later the short interval count reached 3,500. One month later oversensing resulting in six inappropriate shocks, and lead extraction was performed.
The results of lead analysis for the seven returned leads are shown in Table 2. There was an excellent correlation between the presumed clinical diagnosis and the results of analysis of the failed ICD leads. Six of the seven patients had evidence of MIO from lead analysis, and this was predicted based on the finding of oversensing during sinus rhythm.
|
| Discussion |
|---|
|
|
|---|
The high failure rate of the Medtronic 6936 ICD lead observed in our study is similar to that reported by others, including the manufacturer (10,18,20). Luria et al. (10) and Hauser et al. (18) have both reported failure rates for the 6936 and other similar coaxial polyurethane ICD leads of close to 20% at four years. The major presentation of lead failure was due to oversensing in all three studies. The reliability of this estimate is decreased due to inconsistent follow-up and loss of patients over time to death from heart failure and other causes. It is likely that we have also underestimated the number of lead failures, as follow-up testing has identified three patients with high shocking lead impedance undergoing intensified follow-up.
Careful study of the Kaplan-Meier curve shows that the increasing failure rate is noted primarily during long-term follow-up. A lead database that follows large numbers of patients until death is necessary to detect lead problems that occur primarily during late follow-up or with such a low incidence that investigators with small numbers of patients may not detect a problem. It is possible with continued long-term follow-up that many ICD leads will demonstrate more late problems.
Failure of pacing or defibrillation leads due to breakdown of polyurethane is not a new finding (2123). Polyurethane breakdown, in most cases due to MIO, has been shown to be the mode of failure for most coaxial polyurethane pacing leads. Polyurethane polymers and the production of complex coaxial leads seem to be the combination that results in the highest incidence of lead failures. The middle insulation layer of the 6936 is 80A polyurethane, which is the same polyurethane that was used to manufacture Medtronic 4004 and 4012 leads. The insulation degradation presumably occurs over time in high-stress areas.
This study identifies a new presentation for polyurethane lead failure. In two patients appropriate shock therapy was delivered for ventricular tachycardia, followed by oversensing for several seconds immediately after shock. In four patients oversensing was also demonstrated intermittently during sinus rhythm and after an inappropriate shock. A possible explanation is this mode of failure represents a noncontact defect between the pace/sense ring conductor and the right ventricular high voltage conductor. It is likely that this problem remains clinically "silent" and is not exposed until a high-voltage shock is delivered. After a shock, the pace/sense conductor is hyperpolarized, and disturbance of the polarization potential due to cyclical loading during the cardiac cycle leads to electrical transients resulting in redetection and a succession of shocks. This polarization potential may linger for 10 min or longer. This can be confirmed by measurement of a decrease in the ring-coil impedance. Another possible cause for these observations is that the metal-to-metal contact occurs after powerful muscle contractions where one conductor has a large amount of postshock polarization voltage. The exposed conductors then generate high-voltage artifacts as they scrape together. This mode of failure may be a "signature" for 6936-lead failure and had not been previously reported.
The short interval counter or sensing integrity counter keeps track of the number of short nonpaced intervals less than 140 ms. The programmer displays the number of short ventricular intervals that have occurred since the stored data was cleared or the device implanted. This diagnostic proved useful for predicting early lead failure. If the use of the short interval counter to predict lead failure is confirmed in prospective studies, it may be particularly useful for diagnosing lead failures before they become clinically manifest. Detection of a high short interval counter could lead to early lead extraction or closer follow-up. While ring-to-coil impedance is the earliest method of detection, it may not provide a complete assessment of lead integrity. However, a ring-to-coil impedance drop confirmed subsequently by a rise in short interval counter data may be a useful indicator of MIO breach.
Study limitations. Our present study does provide some useful practical information that can be used to guide follow-up of ICD patients. We feel that given the high incidence of late failure of patients with the 6936 ICD lead should undergo more frequent clinic follow-up visits, especially looking for episodes of nonsustained ventricular tachycardia with nonphysiologic intervals. In patients with ICD, pulse generators capable of measuring short interval counters or lead-to-coil impedance, review of this data should be useful to predict eventual ICD lead failure. Routine ventricular fibrillation induction, perhaps on a yearly basis, may also be worthwhile to look for postshock oversensing. We do not perform routine chest radiography during follow-up, so we cannot comment on routine chest radiograph tests to detect lead failures. Changes in pacing or sensing thresholds did not predict lead failures, but the small number of patients with lead failures at the time of testing and the use of different device models calculating impedance in different ways made that data difficult to interpret.
Our findings raise important issues regarding the costs and alternative approaches to patients who have "prophylactic" ICDs. Many of these patients will have a relatively long life span where lead problems (particularly in patients who have multiple transvenous leads) may become a prominent concern. Lead problems result in considerable morbidity and add substantially to health care costs. Ideally, ICD leads with excellent long-term reliability will help leads, but the complex structure and requirements for such leads likely limit the ease with which this goal may be achieved. Consideration of novel approaches to these patients such as "leadless" ICDs deserves further attention (24).
In summary, ICD lead failures may occur late during follow-up after the lead is implanted. A new mode of ICD lead failure is described, as well as the measurements from the short interval counter and the ring-to-coil impedance, to predict lead failure. Finally, this study highlights the importance of a skilled electrophysiologist performing continued careful clinical follow-up of ICD leads to determine lead long-term reliability.
| References |
|---|
|
|
|---|
This article has been cited by other articles:
![]() |
M. Chinushi, Y. Hosaka, N. Ikarashi, K. Iijima, H. Furushima, and Y. Aizawa Automatic R-wave and impedance testing with the modern patient alert system to reduce inappropriate implantable cardioverter defibrillator shocks due to lead fracture Europace, June 1, 2008; 10(6): 738 - 740. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. C. Nielsen, H. Kottkamp, M. Zabel, E. Aliot, U. Kreutzer, A. Bauer, A. Schuchert, H. Neuser, B. Schumacher, H. Schmidinger, et al. Automatic home monitoring of implantable cardioverter defibrillators Europace, June 1, 2008; 10(6): 729 - 735. [Abstract] [Full Text] [PDF] |
||||
![]() |
W. H. Maisel and D. B. Kramer Implantable Cardioverter-Defibrillator Lead Performance Circulation, May 27, 2008; 117(21): 2721 - 2723. [Full Text] [PDF] |
||||
![]() |
J. Eckstein, M. T. Koller, M. Zabel, D. Kalusche, B. A. Schaer, S. Osswald, and C. Sticherling Necessity for Surgical Revision of Defibrillator Leads Implanted Long-Term: Causes and Management Circulation, May 27, 2008; 117(21): 2727 - 2733. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. Rozner Management of Implanted Cardiac Defibrillators During Eye Surgery Anesth. Analg., February 1, 2008; 106(2): 671 - 672. [Full Text] [PDF] |
||||
![]() |
T. Rauwolf, M. Guenther, N. Hass, A. Schnabel, M. Bock, M.U. Braun, and R.H. Strasser Ventricular oversensing in 518 patients with implanted cardiac defibrillators: incidence, complications, and solutions Europace, November 1, 2007; 9(11): 1041 - 1047. [Abstract] [Full Text] [PDF] |
||||
![]() |
T. Kleemann, T. Becker, K. Doenges, M. Vater, J. Senges, S. Schneider, W. Saggau, U. Weisse, and K. Seidl Response to Letter Regarding Article, "Annual Rate of Transvenous Defibrillation Lead Defects in Cardioverter-Defibrillators Over a Period of >10 Years" Circulation, October 30, 2007; 116(18): e513 - e513. [Full Text] [PDF] |
||||
![]() |
J. A. Ezekowitz, B. H. Rowe, D. M. Dryden, N. Hooton, B. Vandermeer, C. Spooner, and F. A. McAlister Systematic Review: Implantable Cardioverter Defibrillators for Adults with Left Ventricular Systolic Dysfunction Ann Intern Med, August 21, 2007; 147(4): 251 - 262. [Abstract] [Full Text] [PDF] |
||||
![]() |
W. H. Maisel Transvenous Implantable Cardioverter-Defibrillator Leads: The Weakest Link Circulation, May 15, 2007; 115(19): 2461 - 2463. [Full Text] [PDF] |
||||
![]() |
T. Kleemann, T. Becker, K. Doenges, M. Vater, J. Senges, S. Schneider, W. Saggau, U. Weisse, and K. Seidl Annual Rate of Transvenous Defibrillation Lead Defects in Implantable Cardioverter-Defibrillators Over a Period of >10 Years Circulation, May 15, 2007; 115(19): 2474 - 2480. [Abstract] [Full Text] [PDF] |
||||
![]() |
D. Vollmann, L. Luthje, and M. Zabel Unusual cause for an increase of the sensing integrity counter in a patient with inappropriate implantable cardioverter-defibrillator therapy Europace, May 1, 2007; 9(5): 275 - 277. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. H. Schoenfeld Contemporary Pacemaker and Defibrillator Device Therapy: Challenges Confronting the General Cardiologist Circulation, February 6, 2007; 115(5): 638 - 653. [Full Text] [PDF] |
||||
![]() |
E. Occhetta, M. Bortnik, A. Magnani, G. Francalacci, and P. Marino Inappropriate implantable cardioverter-defibrillator discharges unrelated to supraventricular tachyarrhythmias Europace, October 1, 2006; 8(10): 863 - 869. [Abstract] [Full Text] [PDF] |
||||
![]() |
Developed in Collaboration With the European Heart, D. P. Zipes, A. J. Camm, M. Borggrefe, A. E. Buxton, B. Chaitman, M. Fromer, G. Gregoratos, G. Klein, A. J. Moss, et al. ACC/AHA/ESC 2006 Guidelines for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death: A Report of the American College of Cardiology/American Heart Association Task Force and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Develop Guidelines for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death) J. Am. Coll. Cardiol., September 5, 2006; 48(5): e247 - e346. [Full Text] [PDF] |
||||
![]() |
Writing Committee Members, D. P. Zipes, A. J. Camm, M. Borggrefe, A. E. Buxton, B. Chaitman, M. Fromer, G. Gregoratos, G. Klein, A. J. Moss, et al. ACC/AHA/ESC 2006 guidelines for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death: A report of the American College of Cardiology/American Heart Association Task Force and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Develop Guidelines for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death) Developed in collaboration with the European Heart Rhythm Association and the Heart Rhythm Society Europace, September 1, 2006; 8(9): 746 - 837. [Full Text] [PDF] |
||||
![]() |
D. Vollmann, A. Erdogan, E. Himmrich, J. Neuzner, D. Becker, C. Unterberg-Buchwald, J. Sperzel, and for the SAFE Study Investigators Patient AlertTM to detect ICD lead failure: efficacy, limitations, and implications for future algorithms. Europace, January 1, 2006; 8(5): 371 - 376. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. C. Senges-Becker, M. Klostermann, R. Becker, A. Bauer, K. E. Siegler, H. A. Katus, and W. Schoels What is the "Optimal" follow-up schedule for ICD patients? Europace, January 1, 2005; 7(4): 319 - 326. [Abstract] [Full Text] [PDF] |
||||
![]() |
B. D. Gunderson, A. S. Patel, C. A. Bounds, R. K. Shepard, M. A. Wood, and K. A. Ellenbogen An algorithm to predict implantable cardioverter-defibrillator lead failure J. Am. Coll. Cardiol., November 2, 2004; 44(9): 1898 - 1902. [Abstract] [Full Text] [PDF] |
||||
![]() |
R. Becker, J. Ruf-Richter, J. C. Senges-Becker, A. Bauer, S. Weretka, F. Voss, H. A. Katus, and W. Schoels Patient alert in implantable cardioverter defibrillators: toy or tool? J. Am. Coll. Cardiol., July 7, 2004; 44(1): 95 - 98. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. Roguin, C. S. Bomma, K. Nasir, H. Tandri, C. Tichnell, C. James, J. Rutberg, J. Crosson, P. J. Spevak, R. D. Berger, et al. Implantable Cardioverter-Defibrillators in patients with arrhythmogenic right ventricular Dysplasia/Cardiomyopathy J. Am. Coll. Cardiol., May 19, 2004; 43(10): 1843 - 1852. [Abstract] [Full Text] [PDF] |
||||
![]() |
T. Wichter, M. Paul, C. Wollmann, T. Acil, P. Gerdes, O. Ashraf, T. D.T. Tjan, R. Soeparwata, M. Block, M. Borggrefe, et al. Implantable Cardioverter/Defibrillator Therapy in Arrhythmogenic Right Ventricular Cardiomyopathy: Single-Center Experience of Long-Term Follow-Up and Complications in 60 Patients Circulation, March 30, 2004; 109(12): 1503 - 1508. [Abstract] [Full Text] [PDF] |
||||
![]() |
Lead Failure Remains the Achilles' Heel of the ICD Journal Watch Cardiology, February 21, 2003; 2003(221): 2 - 2. [Full Text] |
||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | SUBSCRIPTIONS | CURRENT ISSUE | PAST ISSUES | CARDIOSOURCE | SEARCH | HELP | FEEDBACK |