Riata implantable cardioverter-defibrillator lead failure: Analysis of explanted leads with a unique insulation defect

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1 Riata implantable cardioverter-defibrillator lead failure: Analysis of explanted leads with a unique insulation defect Robert G. Hauser, MD, FHRS, Deepa McGriff, BS, Linda Kallinen Retel, BS, FHRS From the Minneapolis Heart Institute Foundation, Minneapolis, Minnesota. BACKGROUND The Riata family of implantable cardioverter-defibrillator leads (St Jude Medical, Sylmar, CA) appears prone to a unique failure mechanism whereby the conductor cables wear through the silicone insulation from inside-out and are seen outside the lead body (externalized conductors). OBJECTIVE To assess the extent of Riata lead damage associated with inside-out insulation defects and their clinical consequences. METHODS In September 2011, we searched the U.S. Food and Drug Administration s Manufacturers and User Defined Experience medical device database for reports describing Riata lead failures that had been analyzed by the manufacturer. RESULTS The Manufacturers and User Defined Experience search identified 105 leads that had inside-out insulation defects. Eight- French single-coil Riata leads accounted for a higher-thanexpected proportion (25.7%) of the leads with this defect. A total of 226 insulation defects were found in the 105 leads (2.2 defects per lead), including 143 inside-out defects (1.4 defects per lead). The most common location of insulation defects was distal to the proximal coil (n 108). Twenty-eight leads (26.7%) had insideout insulation defects underneath the shocking coils. Of 43 leads whose cables were assessed for the integrity of the ethylenetetrafluoroethylene cable coating, 22 (51.2%) were found to be abraded, exposing the conductor surfaces. On X-ray radiography or fluoroscopy, 7 leads were found to have externalized cables; 2 of these leads had no electrical abnormalities, while 4 exhibited noise or increased impedance. Inappropriate shocks were experienced by 31 of the 105 patients (29.5%). CONCLUSION Riata leads that have inside-out insulation defects often have multiple defects, including additional inside-out abrasions along the body of the lead and beneath the shocking coils. Eight-French single-coil Riata models may be more prone to externalized cables than are dual-coil and 7-F designs. Externalized cables are but one manifestation of interior insulation damage. Our findings question the durability of the ethylene-tetrafluoroethylene cable coating on exposed cables. KEYWORDS Implantable cardioverter-defibrillator; Lead; Insulation; Complications; Failure ABBREVIATIONS ETFE ethylene-tetrafluoroethylene; FDA Food and Drug Administration; ICD implantable cardioverterdefibrillator; MAUDE Manufacturers and User Facility Device Experience (Heart Rhythm 2012;9: ) 2012 Heart Rhythm Society. All rights reserved. Introduction The Riata and Riata ST family of 8-F and 7-F implantable cardioverter-defibrillator (ICD) leads (St Jude Medical, Sylmar, CA) appear prone to a unique failure mechanism whereby the conductor cables wear through the silicone insulation (inside-out abrasion) and appear outside the lead body (externalized conductors) (Figure 1). 1 5 Recent studies suggest Riata failure rates of 8% 15%, including leads that are electrically intact but that exhibit externalized conductors. 6,7 The leads may function normally because the highvoltage and pace-sense cables are covered with ethylenetetrafluoroethylene (ETFE), which serves as a second insulating barrier (Figure 2). However, the reliability of ETFE on exposed conductors in patients is unknown. While published reports have focused on externalized conductors, little is known of Riata insulation or conductor defects associated with inside-out abrasions. The December Address reprint requests and correspondence: Dr Robert G. Hauser, MD, Minneapolis Heart Institute Foundation, th Str, Suite 500, Minneapolis, MN address: rhauser747@aol.com letter from St Jude Medical 8 acknowledged that it had found insulation defects in Riata and Riata ST leads returned for product analysis, including in-the-pocket lead to pulse generator can abrasion, intravascular or intracardiac lead-to-lead abrasion, and lead abrasion caused by intracardiac and extravascular anatomic structures, such as the tricuspid valve apparatus and the clavicle. The purpose of this study was to assess the extent of Riata lead damage associated with inside-out insulation abrasions and the clinical consequences as reported by the manufacturer to the U.S. Food and Drug Administration (FDA) and available online in the FDA s Manufacturers and User Facility Device Experience (MAUDE) database. Methods Riata and Riata ST leads The 8-F Riata ICD lead was market released in the United States in March 2002, and it was removed from distribution in 2010 after approximately 227,000 leads were sold worldwide, including 144,579 U.S. implants (Table 1). 8 The Riata ST models, which were introduced in 2005, are 7-F-diam /$ -see front matter 2012 Heart Rhythm Society. All rights reserved. doi: /j.hrthm

2 Hauser et al Riata ICD Lead Failure 743 Figure 1 Extracted dual-coil Riata lead showing externalized cables (arrows) in 2 locations between the proximal and distal coils. eter leads. Riata and Riata ST leads were insulated with pure silicone rubber; in 2006, a proprietary silicone-polyurethane copolymer (Optim TM, St Jude Medical, Sylmar, CA) covering was added to Riata ST Optim models. The multilumen construction of these leads is illustrated in Figure 2. The high-voltage and 2 pace-sense cables were extruded with 1.5 mil ( in) of ETFE, and the pace-sense conductor coil was strung through a tube of polytetrafluoroethylene. Definitions Externalized conductors are cables that have breached the outer insulation and are visible outside the lead body (Figure 1); approximately 85% of the externalized conductors are caused by inside-out insulation abrasions, and 15% are associated with outside-in insulation abrasions. 9 Inside-out abrasion is an insulation defect caused by the relative motion of the cables within the lead insulation lumen (Figure 2, arrows); this defect begins as a silicone abrasion and creeps outward to the surface of the lead body. Outside-in abrasion is an insulation defect caused by contact with another lead or anatomic structure; it begins with a surface abrasion. A can abrasion is an insulation defect caused by the lead contact with the pulse generator housing in the pocket; can abrasions can cause short circuiting between a high-voltage cable and the pulse generator. FDA s MAUDE database The MAUDE database contains reports of adverse events involving medical devices. In our experience, 10,11 the vast majority of reports originate from manufacturers, and a small percentage is submitted by user facilities. The FDA requires manufacturers to report adverse events that are communicated to them verbally or in writing, and they must report the results of investigations into the causes of device malfunctions. The relevant data items for each event include (1) model number, (2) report source (eg, hospital or manufacturer), (3) event location, (4) date of event and report, (5) device age, (6) patient outcome, and (7) narrative of event and manufacturers analysis of returned devices. MAUDE reports are available online at html. The FDA updates the database about every 2 months; consequently, there may be a delay between the time a report is filed and when it is posted on the FDA s Web site. Previous reports from this center have focused on MAUDE data for ICD pulse generator and lead failures and deaths associated with lead extraction devices. 10,11 We searched the MAUDE database on September 6, 2011, for Riata lead failures by using the search term inside-out abrasion. We also searched the MAUDE database by using the search term Riata lead failure. All the reports returned by the search were from the manufacturer. Results The MAUDE search found 107 Riata leads that had insideout insulation abrasions (Table 1); 105 of these leads were analyzed by St Jude Medical, and 2 leads were not analyzed because they were abandoned in situ and replaced during surgical revisions after externalized cables were seen on fluoroscopy. The MAUDE search for Riata lead failure returned 721 reports; thus, inside-out abrasions were approximately 15% of Riata lead failures. The single-coil leads (models 7002, 1592, 1582, 1572) accounted for 25.7% of the leads in this study even though they represent only Figure 2 Cross sections of 8-F silicone Riata single-coil (A) and dual-coil (B) high-voltage implantable cardioverter-defibrillator leads. The cables are coated in ethylene-tetrafluoroethylene, which are shown in blue, and the central coil pace-sense conductor with a stylet lumen is encased in a tube of polytetrafluoroethylene, which is shown in green. Arrows indicate location and direction of inside-out abrasion.

3 744 Heart Rhythm, Vol 9, No 5, May 2012 Table 1 Characteristics of explanted and returned Riata and Riata ST leads that St Jude Medical analyzed and found to have insideout insulation abrasions Model Number in this study Insulation Coils/fixation Diameter (F) Year of market release Number of U.S. implants Riata ST 7040, Silicone Dual, passive , Riata ST Silicone Single, active , Riata ST 7000, Silicone Dual, active , Riata 1590, Silicone Dual, active , Riata Silicone Single active Riata Silicone Single, active , Riata Silicone Single, passive Riata 1570, Silicone Dual, passive , Riata 1580, Silicone Dual, active , Total , Percentage of U.S. implants 10.7% of the leads sold in the United States. The average age of the 105 analyzed leads was months (range months). The 2 leads that were not analyzed (aged 85 and 57 months) were abandoned in situ and replaced during surgical revisions after externalized cables were seen on fluoroscopy. Clinical observations and engineering analyses Table 2 provides data for each of the 105 leads that were found to have one or more inside-out insulation abrasions, including those that were discovered incidentally and were not the immediate cause of failure. A total of 226 insulation defects were found, including 143 insideout defects. The most common location of insulation defects was distal to the region of the proximal coil (n 108) (Figure 3). The majority of leads (69 of 105; 65.7%) had multiple insulation defects, and many of these (30 of 69; 43.5%) had typical insulation defects caused by can abrasions. Some insulation abrasions were caused by contact with another lead or vascular or cardiac structures (outside-in abrasion). Twenty-eight of the 105 leads (26.7%) had inside-out insulation defects underneath one or more of the highvoltage shocking coils. Of these, 23 were 8-F Riata and 5 were 7-F Riata ST leads; thus, 25.8% of Riata leads (23 of 89) and 31.3% of Riata ST leads (5 of 16) had inside-out abrasions under a shocking coil (P.76). Other findings included 32 leads with exposed cables or conductors, and 6 leads had melted cables, presumably owing to one or more high voltage shocks. Of the 43 leads that were assessed for the integrity of the ETFE cable coating, 22 (51.2%) were found to be abraded, exposing the conductor. Signs and clinical consequences of lead failure As shown in Table 2, increased pacing thresholds tended to appear earlier than other signs while impedance changes occurred later. Noise and other sensing issues were the most common signs of failure (Table 3) and developed around 5 years. On x-ray radiography or fluoroscopy, 7 leads were found to have externalized cables; 2 of these leads had no electrical abnormalities, while 4 exhibited noise or oversensing and 1 lead had increased impedance. Inappropriate shocks were experienced by 31 of the 105 patients (29.5%). Inappropriate shocks were associated with abraded ETFE cables; 9 of the 22 patients (40.9%) who had abraded cables received inappropriate shocks, while inappropriate shocks occurred in 3 of the 21 patients (14.2%) whose cables were not abraded (P.088). One death was associated with a can abrasion and truncated high-voltage shock. Discussion The results of this study suggest that failed 8-F Riata and 7-F Riata ST leads with inside-out abrasions frequently have multiple insulation defects that are distributed along the length of the lead. These additional insulation defects (both inside-out and outside-in) are often accompanied by other defects, including exposed cables, fractured and melted conductors, and can abrasions. Sensing abnormalities, including noise on the lead, and impedance changes are the most common electrical abnormalities. A third of the patients in this study experienced serious adverse events, primarily inappropriate shocks, and all patients required surgical intervention. Inside-out insulation abrasion resulting in externalized cables is a unique cause of ICD lead failure. It has been suggested that movement of the cables within the lumens produces outward forces that with time (years) disrupts the silicone insulation and releases the cables outside the body of the lead. 8,11 This may explain the frequent occurrence of externalized cables in the region of the tricuspid valve, but it does not explain the other lead damage we found in this study. We hypothesize that once a cable is exposed and is no longer restrained by the insulation it begins to flex and cause collateral damage, which accumulates over time; the lead damage may be greatest within the heart where flexion is most pronounced. A contributing factor may be the tendency of silicone to flow away from pressure points or creep at body temperature, rather than mechanical abrasion alone. Creep is time dependent, and it can result in permanent thinning of the insulation, reducing its tensile strength and resistance to abrasion. 12 Thus the cause of inside-out insulation failure in Riata and Riata ST leads is likely multifactorial, a combination of cable movement or stacking within the lumens,

4 Hauser et al Riata ICD Lead Failure 745 Table 2 Results of St Jude Medical s engineering analyses of returned Riata and Riata ST leads that were found to have inside-out insulation abrasions as well as the associated clinical signs of failure and patient consequences as reported to the Food and Drug Administration by the manufacturer Model number length Age (mo) Clinical sign of failure Engineering analysis Insulation defects Electrical Other ETFE cable coating Patient consequences 1570/65 32 Noise Multiple Normal Cables exposed 1570/ Impedance, noise Multiple Normal Cables exposed Normal 1570/ Externalized cables Single Cables exposed Partial lead 1580/65 48 Oversensing Single Partial lead 1580/65 59 Oversensing Multiple incl Lead in 2 pieces Normal 1580/ Impedance Multiple Normal 1581/65 53 Loss of capture Multiple Partial lead Normal 7000/65 30 Noise, externalized cables Single Normal Normal 7000/65 40 Abnormal impedance Multiple Normal Clavicular crush 1570/65 57 Abnormal impedance Multiple Cables exposed 1570/65 61 No information Multiple SVC cables exposed Normal 1570/65 69 Oversensing, 1Impedance Multiple Cables exposed Abraded Inappropriate shocks 1570/65 82 Noise Multiple Ring electrode to RV coil contact Abraded Inappropriate shocks 1570/65 96 Noise Single Abrasion below the RV HV coil 1571/65 52 No information Multiple incl 1571/ HV impedance IOA SVC coil SVC and RV coils melted (short circuit) 1572/65 57 Loss of capture Multiple incl IOA involving RV coil Normal Cables exposed 1572/65 90 Aborted shocks, noise Externalized cables 1572/65? Insulation break Multiple Fractured RV shock c 1580/60 48 High threshold Multiple RV cables abraded Abraded 1580/60 60 Oversensing Multiple incl Cables exposed Abraded Inappropriate shocks 1580/60 60 Aborted shocks, noise Multiple incl Abraded 1580/60 70 Abnormal impedance Single Partial lead Normal 1580/60 71 Externalized cables Multiple incl 1580/60 80 Oversensing Multiple incl 1580/65 18 No information Single 1580/65 37 Oversensing, 1Impedance Multiple incl Shorted Abraded 1580/65 48 Noise Single Lead in 2 pieces 1580/65 54 Oversensing Single 1580/65 55 Multiple Partial lead Normal 1580/ Impedance Multiple Cables exposed Abraded Inappropriate shocks 1580/65 62 Loss of capture Single Partial lead 1580/65 65 Noise, insulation defect Multiple Fractures HV cables on x-ray Lead in 2 pieces 1580/65 67 Break Multiple Normal Cables exposed Normal 1580/65 68 Noise Multiple incl Sensing conductors exposed 1580/65 72 No information Multiple 1580/ Threshold, 1Impedance Multiple incl Lead in 2 pieces Normal 1580/65 76 Loss of capture Single

5 746 Heart Rhythm, Vol 9, No 5, May 2012 Table 2 Continued Model number length Age (mo) Clinical sign of failure Engineering analysis Insulation defects Electrical Other ETFE cable coating Patient consequences 1580/65 80 Noise Single Cables exposed Abraded Inappropriate shocks 1580/65 80 Noise, externalized cables Multiple incl 1580/65 96 No information Multiple incl Abraded 1580/65 98 No information Single Normal 1580/ Impedance Multiple incl Cables exposed 1581/60 50 Noise Multiple incl Sensing cable exposed 1581/ Impedance Single Partial lead 1581/ Impedance Single Lead in 2 pieces Normal 1581/ HV impedance Single Melted cables 1581/65 46 No information Single Normal 1581/65 52 No information Multiple incl Melted cables 1581/ Threshold, 2R wave Single Partial lead 1581/65 54 Externalized cables; Multiple incl 1Impedance, noise 1581/65 56 Oversensing Multiple RV cable melted 1581/65 60 Oversensing Multiple incl Abraded 1581/65 63 No information Single 1581/ Impedance Single Clavicular crush 1581/ Impedance Multiple 1Impedance Cables melted 1581/65 77 No information Single Normal 1581/ Impedance Multiple incl Partial lead Abraded 1581/65 79 Short Multiple 1581/65 80 Oversensing Multiple Cables melted 1581/65 82 No information Multiple Normal 1581/ Pacing impedance Multiple incl Abraded 1581/65 98 Loss of sensing and Single Pacing cable and SVC pacing, noise coil contact 1581/65? 1Impedance Multiple incl High impedance Cables melted Death Inappropriate shocks truncated shock 1582/60 55 Noise Single Normal Inappropriate shocks 1582/60 72 No information Single Lead in 2 pieces 1582/60? Oversensing Multiple Cables exposed Abraded Inappropriate shocks 1582/65 15 Insulation break Multiple incl Cables exposed 1582/65 36 Noise 1582/65 55 Noise Multiple Shorted Cables exposed 1582/65 56 Noise Multiple Abraded Inappropriate shocks

6 Hauser et al Riata ICD Lead Failure 747 Table 2 Continued Model number length Age (mo) Clinical sign of failure Engineering analysis Insulation defects Electrical Other ETFE cable coating Patient consequences 1582/65 62 High threshold Multiple incl Cables exposed 1582/65 62 No information Multiple 1582/65 63 Oversensing, noise Multiple Oversensing, noise 1582/65 68 Oversensing Multiple Cables exposed Partial lead 1582/65 72 Oversensing Single Shorted 1582/65 74 No information Multiple Abraded 1582/65 77 X-ray abnormality Multiple Abraded 1582/ Impedance Multiple Cables exposed 1582/65 82 Oversensing Multiple Cables exposed Abraded Inappropriate shocks 1582/ HV impedance Multiple Partial lead Abraded 1582/65 86 Externalized cables, Single abnormal sensing 1582/65 94 Vibratory alert triggered by low impedance Multiple incl Abraded 1582/65? Oversensing Multiple Cables exposed Abraded 1590/60 59 Fracture Multiple Externalized cables No fracture 1590/60 66 Oversensing Single Cables exposed Normal Inappropriate shocks 1591/65 65 Oversensing Multiple incl Cables exposed 1592/65 60 Abnormal impedance Multiple incl Cables exposed 7000/60 33 Noise, oversensing Multiple Shorted 7000/60 42 Oversensing Multiple Insulation abraded owing to friction with another lead 7000/60 53 Oversensing Multiple Abraded 7000/65 33 Noise Multiple External and inside-out abrasions 7000/65 48 Oversensing, externalized Multiple Lead in 2 Cables exposed cables pieces Lead in 2 pieces 7000/65 53 High threshold Single Cables exposed Normal Lead in.2 pieces 7001/ Impedance Single Shorted Cables exposed and melted 7001/65? Fracture Multiple incl Shorted Cables exposed Distal coil fractured Normal Inappropriate shocks 7001/75 23 Insulation break Single 7002/65? Loss of capture Single Normal Cable exposed Normal 7040/65 24 Noise Single Partial lead Abraded Inappropriate shocks 7040/ Impedance, noise Multiple incl 7041/65 55 Undersensing Multiple Cables exposed Normal 1581/65 62 Noise Multiple incl Shorted Multiple inside-out abrasions 1582/65 52 Undersensing Single Shorted Undersensing 1582/65 59 Oversensing Single Shorted 7000/ Impedance Multiple incl Shorted Inappropriate shock ETFE ethylene-tetrafluoroethylene; HV high voltage; IOA inside-out abrasion; SVC Superior Vena Cava; RV right ventricular; incl including.

7 748 Heart Rhythm, Vol 9, No 5, May 2012 A B C Model/ Defect Type No. Leads Total Defects Number of Defects in Each Lead Segment A B* C Unspecified Location Dual Coil Models 1580, Inside-out Outside-in Unspecified , Inside-out Outside-in Unspecified , Inside-out Outside-in , Inside-out Outside-in , Inside-out 3 3 Outside-in Single Coil Models* 1572, 1582, Inside-out Outside-in Inside-out 1 1 Total Figure 3 Location of Riata and Riata ST insulation defects. Note that the proximal coil is not present in single-coil models, and defects in segment B will be in the lead body for single-coil models. which applies pressure against the silicone, causing creep, thinning, and loss of tensile strength. Eventually, the outer insulation (Figure 1) ruptures and tears proximally and distally, uncovering the cables, which may be displaced outside the lead body. The unrestrained cables then produce additional damage as described previously. As shown in Table 1, single-coil leads accounted for 10.7% (15,492 of 144,579) of 8-F Riata and 7-F Riata ST leads sold in the United States. Thus, a larger-than-expected proportion (27 of 105; 25.7%) of leads in this study (Table 1) were single-coil models (Figure 2A). Recently, St Jude Medical reported that 8-F single-coil Riata leads were more prone to externalized conductors than were other Riata silicone models, including the downsized 7-F Riata ST whose 3 cable pairs were positioned closer to a smaller stylet lumen. 9 The addition of a third cable pair to the single-coil Riata ST leads is a unique design feature because this third cable pair provides no electrical function.

8 Hauser et al Riata ICD Lead Failure 749 Table 3 Signs of Riata and Riata ST lead failures with insideout insulation defects Number Impedance changes Increased impedance Decreased impedance Unspecified impedance abnormality 4 4 Sensing Noise on lead Oversensing Decreased R wave/undersensing 3 3 Pacing Loss of captures 6 7 High threshold 5 6 X-ray/fluoroscopic signs 9 10 Fracture or insulation defect 2 2 Externalized cables 7 8 Other 3 3 Total Percentage A quarter of the 105 leads in this study had inside-out defects under a shocking coil, which prevented the cables from externalizing. These defects were seen equally in 8-F Riata and 7-F Riata ST leads. In addition, two 7-F Riata ST leads had externalized cables. Accordingly, while the 7-F Riata ST design changes may have mitigated the 8-F singlecoil lead s propensity to externalize cables, they have not prevented inside-out insulation defects. A critical decision confronting physicians is how to manage patients who are found to have externalized cables. This study was not designed to answer this question, but certain of our findings should be considered when planning follow-up studies. First, many leads in this study were returned in pieces, suggesting that their removal was difficult. St Jude Medical, in its recent letter to physicians, 9 reported 2 deaths and 1 serious injury associated with the extraction of leads with externalized cables. Physicians who have extracted these leads report the need for larger extraction sheaths, which have been shown to be associated with higher complication rates. Second, it is not known how durable the ETFE is on a cable exposed to blood flow and continuous cardiac motion. The thickness of the ETFE on the cables is only approximately 1.5 mil, and its dielectric strength (nominally 4500 V) can be reduced if abraded. While the ETFE may appear to be electrically intact in low-voltage applications, it may not withstand the energy delivered by a high-voltage shock. In this study, we found abraded cables, meaning that the ETFE had been damaged; the patients who had abraded cables tended to receive inappropriate shocks. Studies are needed to determine whether it is feasible to know with a high degree of certainty that externalized cables are durable over time and capable of delivering effective therapy. This study has certain limitations. Some of the lead damage described herein may have been sustained during extraction. However, the manufacturer s reports did not attribute any of the insulation defects to extraction-related damage except to observe that a lead was returned partially or in sections. Inside-out and outside-in insulation defects are the result of chronic changes in the silicone rather than acute damage. Moreover, we have found that extracted silicone Fidelis leads rarely exhibited insulation damage based on returned product analyses. 11 The purpose of this study was to assess leads that had inside-out insulation defects. Thus we did not analyze all Riata and Riata ST failures in MAUDE. To our knowledge, there are no reports in the medical literature of inside-out abrasions involving St Jude Medical leads that employ Optim insulation. In conclusion, failed 8-F Riata and 7-F Riata ST leads that have been explanted and found to have inside-out insulation defects often exhibit multiple insulation defects, including additional inside-out abrasions along the body of the lead and beneath the shocking coils. Eight-French single-coil Riata models may be more prone to externalized cables than are dual-coil Riata and Riata ST models. Externalized cables may be but one manifestation of interior insulation damage caused by chronic, unrestrained cable movement and possibly the inherent tendency of silicone to creep and tear. Lastly, our findings question the reliability of ETFE to insulate cables in leads with inside-out abrasions, especially those that have been exposed, externalized, or continuously flexed. Clinical studies are urgently needed to determine how best to manage patients who have Riata and Riata ST leads. References 1. Duray GZ, Israel CW, Schmitt J, Hohnloser SH. Implantable cardioverterdefibrillator lead disintegration at the level of the tricuspid valve. Heart Rhythm 2008;5: Jalal Z, Derval N, Ploux S, Bordachar P. Unusual failure of a multilumen, small-diameter implantable cardioverter-defibrillator lead. Heart Rhythm 2010; 7: Richards MW, Warren CE, Anderson MH. Late failure of a single-coil transvenous implantable cardioverter-defibrillator lead associated with conductor separation. Europace 2010;12: Valk S, Luitjen R. Jordaens L. Insulation damage in a shock wire: an unexpected fluoroscopic image. Pacing Clin Electrophysiol 2010;33: Krebsbach A, Alhumaid F, Henrickson CA, Calkins H, Berger RD, Cheng A. Premature failure of a Riata defibrillator lead impedance change or inappropriate sensing: a case report and review of the literature. J Cardiovasc Electrophysiol 2011;22: Kodoth V, Cromie N, Lau E, McEneaney D, Wilson C, Roberts MJ. Riata lead failure: a report from Northern Ireland Riata lead screening programme. Available from: &eevtid 48. Accessed December 4, Erkapic D, Duray GZ, Bauernfeind T, De Rosa S, Hohnloser SH. Insulation defects of thin high-voltage ICD leads: an underestimated problem? J Cardiovasc Electrophysiol 2011;22: Chester KM. Important Product Information: St Jude Medical Riata and Riata ST Silicone Endocardial Leads. Sylmar, CA: St Jude Medical; December 15, Carlson M, Tsung P. Medical Device Advisory. Sylmar, CA: St Jude Medical; November 28, Hauser RG, Katsiyiannis WT, Gornick CC, Almquist AK, Kallinen LM. Deaths and cardiovascular injuries due to device-assisted implantable cardioverter-defibrillator and pacemaker lead extraction. Europace 2010;12: Hauser RG, Kallinen LM, Almquist AK, Gornick CC, Katsiyiannis WT. Early failure of a small-diameter high-voltage implantable cardioverter lead. Heart Rhythm 2007;4: Cheremisinoff NP, Cheremisinoff PN, eds. Elastomer Technology Handbook. Harpers Ferry, VA: CRC Press; 1993:66.