A multicenter experience with a bipolar tined polyurethane ventricular lead

Clinical experience with pacemaker pulse generators and transvenous leads: An 8-year prospective multicenter study

BACKGROUND

Pacemakers have improved the lives of patients worldwide. Unfortunately, the medical community has had little independent information regarding the performance of these vital medical devices.

OBJECTIVES

The purpose of this study was to examine the reasons pacemaker pulse generators and transvenous leads were removed from service. We evaluated the causes and major adverse clinical events associated with device end-of-service life behavior and how they were detected and managed.

METHODS

Pulse generator and lead data were entered prospectively using a web-based format. Normal battery depletion was signified by the elective replacement indicator appearing >3 years after implant. Lead failure was a device defect causing pacing, sensing, or fixation malfunction, high threshold, or abnormal impedance. Major adverse clinical events were death, angina, heart failure, syncope, and perioperative surgical complications.

RESULTS

From 1998 to 2006, 2,652 pulse generator and 615 leads were removed from service. The average pulse generator was implanted for 7.3 +/- 3.1 years (range <1 day to 26 years). The majority of pulse generators (n = 2,317 [87%]) were replaced for normal battery depletion. Severe and accelerated battery depletion, manufacturers' advisories, and electronic or connector defects accounted for 13% of pulse generator removals. The proportion of pulse generators removed from service as a result of manufacturers' advisories, electronic failure, and housing defects were 4%, 2%, and 1%, respectively. Models with rate response capability had shorter battery longevities than those without rate response capability. Major adverse clinical events due to pulse generator end-of-service life behavior were related to electronic and connector defects, and both normal and severe battery depletion. Median time to lead failure was 7.2 +/- 5.2 years. Insulation defects caused the majority of lead failures, and most of these leads used polyurethane materials. Lead failure was associated with a 16% incidence of major adverse clinical events. No major adverse clinical events occurred when impending lead failure was detected at routine follow-up. Lead extraction was associated with a 5.6% complication rate, including one death.

CONCLUSION

Overall pulse generator performance was satisfactory. Differences in battery longevity were observed among models. In some patients, elective replacement indicators signifying normal battery depletion resulted in major adverse clinical events. Pacemaker follow-up effectively identified pulse generator end-of-service life and often detected impending lead failure, thus avoiding major adverse clinical events. Long-term studies are needed to assess chronic lead performance so that appropriate clinical management strategies, including recommendations for lead extraction, can be developed.

Multi-Center Clinical Experience with a Lumenless, Catheter-Delivered, Bipolar, Permanent Pacemaker Lead: Implant Safety and Electrical Performance

PURPOSE

Reduced lead diameter and reliability can be designed into transvenous permanent pacing leads through use of redundant insulation and removal of the stylet lumen. The model 3830 lead (Medtronic Inc., Minneapolis, MN, USA) is a bipolar, fixed-screw, steroid-eluting, lumenless, 4.1-Fr pacing lead. Implantation can be performed in a variety of right heart sites using a deflectable catheter (Model 10600, Medtronic). Lead performance and safety were studied.

METHODS

Two prospective trials of 338 implanted subjects from 56 global sites were conducted. Electrical and safety data were obtained at implant, pre-discharge, and up to 18 months post-implant. Leads were implanted at traditional and alternate right heart sites.

RESULTS

The study enrolled 338 subjects (204 males, 70.6 +/- 11.6 years) followed-up for a mean of 10.2 months (range, 0-21.6). Mean P-wave amplitudes ranged from 3.2 mV at 3 months to 2.9 mV at 18 months, while mean atrial pulse width thresholds at 2.5 V ranged from 0.07 ms at 3 months to 0.09 ms at 18 months. Mean R-wave amplitudes ranged from 11.3 mV to 11.1 mV and mean ventricular pulse width thresholds at 2.5 V ranged from 0.10 ms to 0.14 ms. There were 22 ventricular and 12 atrial lead complications within 3 months post-implant. Survival from lead-related complications improved to a clinically acceptable rate in the cohort of patients when revised implant techniques were employed.

CONCLUSIONS

With the use of recommended implant techniques, the study results support the electrical efficacy and safety of a catheter-delivered, lumenless lead in traditional or alternate right atrium or right ventricle sites through 18 months post-implant.

Clinical surveillance of a tined, bipolar, silicone-insulated ventricular pacing lead

AIMS

This study assesses short- and long-term performance of the S80TB ventricular lead manufactured by Sorin Biomedica, Italy.

METHODS AND RESULTS

Three hundred and thirty leads were implanted and had complete follow-up with us for a minimum of 60 months or up to failure, removal, and/or patient death (mean 40 months, range: 1 day to 81 months). Thirty-two patients (9.6%) had spontaneous lead-related complications: 7 (2.1%) occurred during the first week; 25 (7.6%) had chronic complications, of which 20 (6.1%) necessitated re-operations; 3 (0.9%) were lead material failures. Of the 110 re-operations (90 pacemaker replacements and 20 operations due to complications), 7 additional cases (6.4%) were complicated by unique connector damage that occurred during disconnection of the lead from the connector block. The Kaplan-Meier estimated 5-year lead survival free of lead material failure and free of any significant lead complication were 97.9 and 87%, respectively.

CONCLUSION

The S80TB lead demonstrates an acceptable rate of acute and chronic spontaneous complications and very few lead material failures over 5 years of follow-up. However, there seems to be a relatively high incidence of connector damage during disconnection from the connector block. Extra caution is required during those procedures in patients with this lead.

Clinical surveillance of a thin bipolar pacing lead

A total number of 415 co-radial, bipolar pacing leads (189 atrial leads; 226 ventricular leads) were implanted in 228 patients between November 1994 and July 1999. Mean pacing thresholds at the implantation were normal at 0.6 V in the atrium and at 0.4 V in the ventricle with a pulse duration of 0.4-0.5 ms. Lead impedance was relatively low (337-447 ohms for atrial leads; 369-459 ohms for ventricular leads) at the implantation and during the follow-up periods. No definite failure in lead materials was observed in either atrial or ventricular leads (mean follow-up of 19.7 and 19.2 months, respectively: up to 52.9 months for both leads). Predicted clinical surveillance up to 10 years calculated statistically showed that the upper 95% confidence limit was a constant of 100%. The lower 95% confidence limits at 5, 7, and 10 years were estimated to be 98.0%, 97.2%, and 96.0%, respectively. From the present study, the ThinLine lead is reliable for both sensing and pacing thresholds, and has excellent predicted lead longevity. Nevertheless, further observation is required regarding cost performance, such as early replacement of the pacemaker generator, because of the lower pacing lead impedance.

Updated appraisal of pacing lead performance from the Danish Pacemaker Register: the reliability of bipolar pacing leads has improved

The Danish Pacemaker Register was established in January 1982, and the 12 implanting centers in Denmark report to the Register on a continuous basis by use of the European Pacemaker Patient Identification Card. As of August 1999, the Register contained data on 33,164 bradycardia, endocardial, and epicardial (n = 159) lead implants performed in Denmark on 27,738 generators in 24,180 patients for a total of 17,988 (54.2%) ventricular unipolar, 5,610 (16.9%) ventricular bipolar, 2,056 (6.2%) atrial unipolar, and 7,242 (21.8%) atrial bipolar leads. Lead failure was defined as need for replacement or surgical abandonment of the lead due to pacing or sensing problems with the exception of lead displacement. The 10-year survival rate for unipolar leads was 97.2 +/- 0.4% (+/- 2 SE) as compared to 79.6 +/- 3.2% for bipolar leads (P < 0.001). The Medtronic 4012, the Telectronics 284, and the Siemens (Pacesetter) 1010T, 105T, and 1050T bipolar lead models were poor performing leads that needed careful monitoring and appropriate replacement. Excluding those five poor performing bipolar leads, the models yielded a 10-year survival rate of 94.3 +/- 2.4% for bipolar leads. The 5-year survival for all bipolar leads implanted after January 18, 1993 (this was the date that the last of the five poor performing bipolar lead models were implanted in Denmark) was 98.7 +/- 0.4% compared with 98.9 +/- 0.3% for all unipolar leads implanted after January 18, 1993 and 86.8 +/- 1.6% for all bipolar leads implanted on or before January 18, 1993. These results indicate a significant improvement in bipolar lead reliability.

Clinical surveillance of a tined, bipolar, J-shaped, steroid-eluting, silicone-insulated atrial pacing lead

Since 1990, 558 Medtronic 5524 bipolar, silicone-insulated, J-shaped, tined, steroid-eluting atrial leads have been implanted at the Mayo Clinic (Rochester, MN, USA) and the Midelfort Clinic (Eau Claire, WI, USA). Implantation data were favorable, with pacing thresholds at implantation (median threshold, 0.6 V) better than most published data on other atrial leads. The rate of acute lead-related complications (dislodgment and diaphragmatic pacing) necessitating reoperation or electrical abandonment of the atrial lead was 0.9%. This rate is lower than that in most published series of atrial leads. Over a median follow-up time of 17.5 months (up to 69 months), there were no chronic lead-related complications and no definite or suspected failures of lead material. This rate is much lower than that with other atrial leads studied previously. We conclude that the Medtronic 5524 atrial lead combines the reliability of silicone insulation with a lack of chronic complications and high thresholds due to its steroid elution and with stability in the atrium due to its J shape despite a passive fixation mechanism. There is no evidence of lead material failure during up to 6 years of follow-up.

Clinical surveillance of a tined, bipolar, steroid-eluting, silicone-insulated ventricular pacing lead

Since 1990, 1,068 Medtronic 5024 bipolar, silicone-insulated, tined, steroid-eluting ventricular leads have been implanted at the Mayo Clinic (Rochester, MN) and Midelfort Clinic (Eau Claire, WI). Implantation data were favorable: median pacing thresholds of 0.5 V at 0.5 ms, median R wave of 13.4 mV, and median impedance of 593 omega. Of the 2.1% acute lead-related complications (dislodgment, microdislocation, diaphragmatic pacing, and undersensing), 1.2% necessitated reoperation. This rate is lower than that in most published series of other leads. During a median follow-up of 23 months (up to 76 months), 12 (1.1%) chronic lead-related complications (high thresholds, loss of capture, and undersensing) and no instances of definite or suspected lead material failure occurred. This rate is much lower than that in studies of other leads. Thus, the 5024 lead combines the reliability of silicone insulation with a low rate of chronic complications that is probably the result of its steroid elution. No evidence of failure of lead material has appeared up to 6 years after implantation.

Pacemaker leads: performance and progress

Pacing leads remain the "weaker link" of the permanent pacing system. Lead failure has been an issue since the beginning of implantable pacemaker therapy. Modern electronics have brought about considerable progress in pacing technology, but lead design has been slower to evolve and problems persist. IS-1 standardization must be considered a significant advance, but some issues regarding IS-1 standardization persist and have been the cause of some compatibility problems. With respect to lead insulation, silicone has proved to offer total reliability for > 30 years. In the search for better handling characteristics, polyurethane 80A was employed for bipolar leads, but it failed to demonstrate satisfactory insulating properties. New insulation materials, such as ethylene-fluoro-ethylene (ETFE), and coated wire technology look promising, having shown 99.32% survival at 5-year follow-up. Reliability is the main objective in lead design, but leads should provide low battery consumption as well. Low coil resistance, with high electrode impedance in steroid-eluting leads, is the standard at present. Low polarization is a desirable property for 2 main reasons: (1) in conjunction with low-threshold leads, it decreases battery consumption; and (2) it allows capture detection and, therefore, safer pacing at low battery consumption. Lead tip design as well as pacing pulse configuration can influence polarization.

Insulation lead failure: is it a matter of insulation coating, venous approach, or both?

Lead insulation material and implant route have a major impact on lead reliability and durability. We compare the incidence of lead insulation failure resulting from both the venous approach and insulation type. Two hundred ninety consecutive leads were followed for a mean period of 57 +/- 30 months; leads with < 1 year follow-up were excluded. There were 116 Silicone Rubber insulated leads and 174 with polyurethane (151 Pellethane 80A and 23 Pellethane 55D) insulation; 279 leads were bipolar and 11 unipolar; 274 leads were implanted in the ventricle and 66 in the atrium. The venous route was the subclavian vein for 170 leads (58%) and the cephalic vein for 120 leads (42%). Insulation failure was diagnosed when a single sign of oversensing, undersensing, failure to capture, early pulse battery depletion, and lead impedance < 250 omega was present. Measurement of lead impedance was performed intraoperatively at implantation and during lead revision or pulse generator replacement. Lead failure caused by conductor coil fracture was not considered. There were 13 lead insulation failures, all among leads with polyurethane insulation (12 Pellethane 80A and 1 Pellethane 55D). Eleven failures (10%) occurred when the subclavian vein and 2 (3%) when the cephalic vein approach was used. The cumulative survival rate of polyurethane and silicone rubber insulated leads was 88.7% and 100%, respectively (P = 0.02); the cumulative survival rate of polyurethane insulated leads was 83.2% when the subclavian vein and 95.1% when the cephalic vein were used (P = 0.03). The mean time to polyurethane lead failure when the subclavian vein approach was used was 54 +/- 17 months and when the cephalic route was 73 +/- 4 months (P < 0.02). By multivariate analysis, the route of entry was found to be a significant variable related to polyurethane insulated lead failure (P < 0.05). At lead revision failure to capture was present in 7, oversensing in 4, and undersensing in 2 instances; impedance was < 250 omega in all cases. Pellethane 80A insulated leads are prone to insulation failure, but more when the subclavian vein is used, rather than the cephalic vein.

Ambulatory electrocardiography for the detection of pacemaker lead failure

The suboptimal performance of some polyurethane bipolar pacing leads has highlighted concern about the optimal method of monitoring pacemaker lead performance. Since the manifestations of premature lead failure may be initially intermittent, we hypothesized that ambulatory electrocardiography (AECG) would be a more sensitive tool for the detection of pacing lead failure compared to increased pacemaker clinic surveillance. Since the Medtronic safety alerts on the 4012, 4082, and 4004 leads, we have followed 261 patients by serial AECG and 165 patients by increased pacemaker clinic surveillance. Lead failures were identified in 75 patients: 68 in the AECG group (31%) and 7 in the clinic group (4%, P < 0.001). Repeat AECG confirmed the lead failure in 38 (97%) of 39 patients in which it could be done. Pacing lead failure documented by AECG could be confirmed by a subsequent clinic assessment in only 15 (25%) of 60 patients evaluated (P < 0.001). The actuarial survival of the 4012 lead was significantly lower in the AECG group compared to the clinic group (56% vs 87% survival at 8 years, P < 0.002). Similar trends were observed for the 4082 and 4004 leads. AECG is a more sensitive method of surveillance for pacemaker lead function compared to pacemaker clinic assessment. AECG should be incorporated into the routine follow-up of pacemaker patients.

Clinical evaluation of a thin bipolar pacing lead

The main disadvantages of bipolar pacing leads have traditionally been related to their relative thickness and stiffness compared to unipolar leads. In a new "drawn filled tube" plus "coated wire" technology, each conductor strand is composed of MP35N tubing filled with silver core and coated with a thin ETFE polymer insulation material. This and parallel winding of single anode and cathode conductors into a single bifilar coil resulted in a bipolar lead (ThinLine, Intermedics) with a body diameter and flexibility similar to unipolar leads. The lead is tined, polyurethane, with the cathode and the anode made of iridium-oxide-coated titanium (IROX). The slotted 8-mm2 cathode tip is coated with polyethylene glycol, a blood soluble material. We present the clinical evaluation results from four pacemaker clinics, where 47 leads (23 atrial-J model 432-04 and 24 ventricular model 430-10) were implanted in 25 patients and followed for up to 2 years. The lead handling characteristics were found to be very satisfactory. Electrical parameters of the leads were measured at implant and noninvasively on postoperative days 1, 2, 21, 42, and months 3, 6, 12, and 24. Mean chronic pulse width thresholds at 2.5 V were 0.14 +/- 0.05 ms in the atrium and 0.10 +/- 0.02 ms in the ventricle, pacing impedances 443 +/- 104 omega and 520 +/- 241 omega, while median electrogram amplitudes were > or = 3.5 mV and > or = 7 mV, respectively. Pacing impedances and thresholds were found to be slightly but statistically significantly higher in unipolar than in bipolar configuration--the findings are explainable by the lead construction. One of 47 leads failed 3 weeks after implant; the conductors were short circuited due to an error during the manufacturing process. We conclude that the new lead thus far has demonstrated appropriate mechanical and electrical characteristics.

Bipolar leads for use with permanently implantable cardiac pacing systems: a review of limitations of traditional and coaxial configurations and the development and testing of new conductor, insulation, and electrode designs

The unacceptable rate of mechanical failures, threshold problems, and recalls experienced with many coaxial bipolar cardiac pacing lead designs are reviewed in detail. To address these problems, redundant insulation coradial atrial and ventricular tined leads (AL and VL, respectively) with iridium oxide electrodes were developed and subjected to extensive accelerated testing. There were no mechanical failures. The new lead body design proved to be much more durable than widely used trifilar MP35N configurations. The data reviewed and early and current test results are strongly supportive of tightly coupled insulation being a major factor in improving lead durability as long as the insulating material is not stressed. In addition to improving flex life, insulation adherence to the conductor may reduce the potential for ionic degradation. Pacing and sensing thresholds in animal studies of the new leads were within the reported range for leads with steroid eluting electrodes. A multicenter Canadian clinical trial was initiated with the first implant in early January 1994. By November 1995, 110 VL and 82 AL had been placed in 124 patients and followed for a mean of 11 +/- 6 months; maximum 21, total 1355. There were 60 males and 64 females with a mean age of 64 +/- 16 years, range 15-88. Primary indications for pacing were AV block in 61 patients, sick sinus syndrome in 53, vasovagal syncope in 4, and congestive heart failure in 7. Many patients had associated or primary tachyarrhythmias, including 111 with supraventricular and 12 with ventricular. Forty-two percent of patients (52/124) had prior cardiac procedures, including 18 open heart surgeries and 20 AV nodal ablations. At implant, 8 lead characteristics were rated good or excellent in 90% (746/829) of evaluations. X-ray visibility was of concern in 10% of patients (12/124). Three perioperative complications occurred, including displacement of one AL (1.2%) and one VL (0.9%). There were no subsequent mechanical (connector, conductor, or insulation) or functional (exit block, micro or macro displacement, or over- or undersensing) problems. Implant pacing thresholds (PT) at 0.45 ms were AL, 0.6 +/- 0.2 (74) and VL 0.4 +/- 0.2 V; impedance (Z) at 3.5 V output AL 373 +/- 77 (82) and VL 497 +/- 117 omega. Sensing thresholds (ST) were AL 3.1 +/- 1.6 (74) and VL 10.3 +/- 4.9 mV. Ventricular lead data were obtained for all patients (N = 110). Atrial lead data are incomplete, because some patients were in atrial fibrillation during implantation. After 12 months, AL PT at 1.5 V output was 0.18 +/- 0.10 ms (21) and at 2.5 V was 0.10 +/- 0.053 (22). Associated AL ST was 3.3 +/- 0.9 mV (21) AL Z 500 +/- 65 omega (25). After 18 months VL PT at 1.5 V was 0.15 +/- 0.10 ms (9) and at 2.5 V output was 0.09 +/- 0.04 ms (9). Associated VL ST was > 7.5 +/- 2.4 mV (9) and VL Z 497 +/- 105 omega (9). Follow-up time discrepancy is due to the VL being available 6 months earlier than the AL. There were no 30-day deaths and only one late death at 10 months in a patient with chronic atrial fibrillation. Death was unrelated to pacer or lead function. At 1 year, 68% AL (15/22) and 62% (24/39) captured at 0.5 V and < or = 1 ms pulse width output. Innovative adherent insulation coradial bipolar lead conductors of the design studied combined with coated iridium oxide electrodes provide for a negligible incidence of mechanical or functional failure with clinical follow-up now approaching 3 years. Excellent acute and chronic sensing and pacing thresholds have been documented. Late thresholds have continued to improve gradually. Long-term clinical pacing at < or = 1.5 V output with a large safety margin is feasible in essentially all patients. This coradial design produces very flexible < 5 French bipolar redundantly insulated lead bodies allowing both AL and VL to simultaneously pass through a single 10 French introducer sheath. (ABSTRACT TRUNCATED)

Clinical presentation of endocardial pacing lead malfunction

This study highlights the wide spectrum of manifestation of pacing lead malfunction. Patients judged to be pacer dependent or in whom ventricular lead malfunction is suspected, and patients with severe symptoms before pacemaker implantation, should be considered at high risk for the development of hemodynamic compromise; prompt hospital admission and pacing lead replacement should be performed.

Failure rates of leads, pulse generators, and programmers have not diminished over the last 20 years: formal monitoring of performance is still needed. BILITCH Registry and STIMAREC

Formal Monitoring of Performance is Still Needed. In order to detect trends in the number of device or component failures that have occurred among permanent pacemaker systems since the 1970s, we reviewed the data of the five largest pacemaker manufacturers from the Bilitch Registry of permanent pacemaker pulse generators, the Stimarec failure registry, the general accounting office summaries of the United States Veterans Administration (VA) Registry of Pacemaker Leads, and the Implantable Lead Registry, from the Cleveland Clinic Lead registry, and the recalls and safety alerts issued by the United States Food and Drug Administration (FDA) over the last 20 years. The definition of failure followed the criterion, or criteria, developed within each registry and differed significantly between the registries. The 20-year period between 1976 and 1995 was divided into 5-year quartiles (QT): QT 1 = 1976-1980; QT2 = 1981-1985; QT3 = 1986-1990; and QT4 = 1991-1995. For pulse generators, the number of models with failures in each quartile in the Bilitch Registry were: QT 1 = 9; QT 2 = 11; QT3 = 17; QT4 = 13. In Stimarec, the number of units reported as having reached a dangerous condition were: QT1 = 710; QT2 = 212; QT3 = 114; QT4 = 310. From the FDA reports, the number of units included in recalls or safety alerts were: QT3 = 6,085; QT4 = 135,766. For permanent pacemaker leads, the numbers of failed or dangerous leads recorded in Stimarec were: QT3 = 16; QT4 = 32. In the VA Registry, the number of models having a below average survival was 2/92 (2.7%). In the Implantable Lead Registry, the number of models having a below average survival was 3/21 (14%). In the Cleveland Clinic series, 6/13 (46%) of lead models were recognized to have some failure involving the conductor, insulation, or connector. In the FDA reports, the number of leads involved in either recall or safety alert were: QT3 = 20,354; QT4 = 332,105. For programmers, the number of units involved either in a recall or safety alert were: QT3 = 11,124; QT4 = 3,528. In all of these series, each of the five largest manufacturers had some models or units involved in each time period. This review of programs has revealed: 1. The incidence of failures, recalls, or safety alerts did not decline over time; and 2. Despite changes in technology, formal monitoring of pacemaker systems is still warranted.

Short- and long-term results with an active-fixation, bipolar, polyurethane-insulated atrial pacing lead

Since 1989, 136 Medtronic 4058 and 4058M bipolar atrial screw-in leads have been implanted at the Mayo Clinic. Early lead related complications included dislodgment in 4 (2.9%). Over a median follow-up time of 14.4 months (1 day to 3.3 years), there were 11 lead related complications (undersensing, failure to capture, diaphragmatic pacing, and gross lead dislodgment). Chronic complications resulted in reoperations in four patients (2.9%). Of 77 patients in whom pacing thresholds were measured between 2 and 4 months after implantation, 9 (11.7%) and 2 (2.6%) had high pacing thresholds and very high thresholds, respectively. The Kaplan-Meier estimate of the probability of 1-year complication-free lead survival was 93.5%. There were no lead material failures. We conclude that the 4058/4058M lead implanted in the atrial position has favorable acute and chronic performance data, with a tendency toward high pacing thresholds at 3 months. The cause of this phenomenon and its course over time should be further evaluated.

Appraisal of pacing lead performance from the Danish Pacemaker Register

The Danish Pacemaker Register was established in January 1982, and the 11 implanting centers in Denmark report to the Register on a continuous basis by use of the European Pacemaker Patient Identification Card proposed by the European Working Group on Cardiac Pacing. As of May 1994, the Register contained data on 18,053 lead implants performed in Denmark, i.e., 1,253 (7%) lead implants before 1982, and all the 16,800 initial lead implants since 1982 on 17,020 generators in 15,366 patients for a total of 12,188 (67.5%) ventricular unipolar, 3,178 (17.6%) ventricular bipolar, 1,316 (7.3%) atrial unipolar, and 1,371 (7.6%) atrial bipolar leads. Preformed J shaped leads were used in 3.5% of the atrial implants and active fixation in < 8%. Lead failure was defined as need for replacement or abandonment of the lead due to pacing or sensing problems with the exception of lead displacement. The 10-year survival rate for unipolar atrial and ventricular leads was 95.8% +/- 2.1% (2 standard errors) and 97.1% +/- 0.6%, respectively, as compared to a 4-year survival rate of 91.5% +/- 4.6% and 91.6% +/- 1.7% for bipolar atrial and ventricular leads, and an 8-year survival rate for bipolar ventricular leads of 75.1% +/- 5.0%. The 5-year survival rate for the bipolar Medtronic model 4012 lead was 85.8% +/- 8.1% and 67.4% +/- 7.3% for the bipolar Siemens model 1010T lead, indicating a poor performance. The Siemens lead models 105T and 1050T seem to be performing like the model 1010T. The 5-year survival rate for the bipolar Telectronics model 284 lead was 88.4% +/- 6.2%. The data from the Danish Pacemaker Register confirm the previous reported good survival of unipolar pacing leads irrespective of the chamber paced, and demonstrate that the bipolar Medtronic 4012 lead, the bipolar Telectronics 284 lead, and especially the bipolar Siemens 1010T, 105T, and 1050T models are unreliable leads that need careful monitoring and appropriate replacement.

Atrial "J" pacing lead retention wire fracture: radiographic assessment, incidence of fracture, and clinical management

In November 1994, Telectronics Pacing Systems issued a voluntary recall of their Accufix 330-801 and 329-701 "J"-shaped atrial pacemaker leads. To assess the integrity of the lead, 156 consecutive patients with the Accufix 330-801 atrial lead implanted underwent fluoroscopic screening. Leads were visualized in at least two orthogonal views. When identified, fractured retention wires were classified into one of four groups, depending on the degree of wire extrusion outside of the lead insulation.

RESULTS

Of the 156 patients, 35 patients (22.4%) had a definite retention wire fracture, and an additional 13 patients (8.3%) had indeterminate leads. Neither the age of the patients, the time since lead implant, nor the site of fracture correlated with the incidence of wire fracture. When analyzed to include indeterminate leads that were re-evaluated and found to be fractured, as well as two leads that were identified as being radiographically normal but found to be fractured after extraction, the incidence of retention wire fracture is 25.6% (40 of 156 leads evaluated).

CONCLUSIONS

The incidence of retention wire fracture in the Accufix 330-801 lead is significantly higher than originally reported. Patients should be notified of the potential dangers associated with this lead. Cardiac digital fluoroscopy is an effective method of screening for wire fracture. Leads with fractured retention wires should be extracted and those with normal fluoroscopic appearance should undergo regular fluoroscopic screening.

Multicenter experience with a bipolar tined polyurethane ventricular lead

A multicenter study was undertaken to determine the failure rate of a specific bipolar tined polyurethane ventricular pacing lead, the Medtronic 4004/4004M pacing lead. Seven centers in the United States and Canada implanted 586 Medtronic 4004/4004M pacing leads. The study was designed to determine the probability and clinical manifestations of lead failure. Only failures compatible with an insulation problem were included. The Kaplan-Meier estimate of the percentage of 4004/4004M lead failures within 4 years after implantation was 14.1% (95% confidence interval: 8.5%-19.3%). Failures were manifested as sensing abnormalities, failure to capture, early battery depletion, and significant decrease in measured impedance compared with previous impedance measurements. The observed rate of failure is unacceptable, and strong consideration should be given to replacing the 4004/4004M pacing lead in pacemaker dependent patients and closely monitoring nondependent patients.

Snare removal of a telectronics accufix atrial J retention wire

A voluntary recall of the Telectronics Accufix models 330-801 and 329-701 "J"-shaped atrial pacemaker leads has been issued because of fracture and extrusion of the J-shaped retention wire. Such extrusion can result in laceration of the atrium or surrounding vascular structures. Herein we describe a patient with a fractured and extruded retention wire that was snared and removed percutaneously; the atrial lead was left intact, and pacing function was satisfactory. This unique procedure can be used to avoid the morbidity associated with percutaneous lead extraction or thoracotomy and to prevent potential dislodgment and embolization of the retention wire during lead extraction.

Long-term follow-up of pacemaker lead systems: establishment of standards of quality

The functional details of all 5,405 pacemaker leads implanted on Montefiore Medical Center were contemporaneously recorded between 1960 and May 31, 1993. Some models have been observed for as long as 24 years. Ventricular leads with more than 50 and atrial leads with more than 30 implanted units have been continually and repeatedly subjected to actuarial cumulative survival rate (CSR) analysis during which clinical decisions, such as continued lead implantation, cessation of use, or early withdrawal from service, were made. CSR evaluation for many lead models by the Mantel-Haenszel method allowed comparison of the performance of contemporaneous lead models with older and new technologies. No effect on lead longevity, durability, on mode of end of lead service, lead removal independent of function (e.g., for infection), materials, or physiological failure was found due to an operator or anatomical route of venous access. Multifilar silicone rubber insulated leads have longevity (CSR) superior to monofilar silicone rubber leads. The cumulative survival of silicone rubber insulated monofilar models 6901, 6907, continuous lead (CL), 4 mm, and 2 mm was 79%-91%, 20 years after implantation. Multifilar silicone rubber insulated models 6961 and 4116 had a cumulative survival of 99%-100%, 15 years after implantation. Among multifilar polyurethane insulated leads, distinct longevity differences exist between formulations and contemporaneous models that are normally similar, yielding a bimodal longevity distinction; model 6971 (ventricular) has 95% CSR and 6991U (atrial) has 94% CSR, 10 years after implantation. Both performed less well than other contemporaneous models, which approximate 100% CSR. The 10-year CSR for leads implanted between 1960-1975 (Era 1) is 98.7%, and the 10-year CSR of leads implanted between 1981-1985 (Era 3) is 99.4%. Comparison of individual lead models, and all leads of specific eras, allows development of survival expectations and standards of quality for comparison between contemporaneous lead models and different eras of manufacture. As the highest available lead CSR sets the standard, statistical deviation of a model from the best performance of a specific era should be considered as an indication of reduced quality.

Clinical surveillance of an active fixation, bipolar, polyurethane insulated pacing lead, Part II: The ventricular lead

Since 1989, 72 Telectronics 330-201 active fixation, polyurethane insulated ventricular leads (Accufix) have been implanted at the Mayo Clinic. There were four (5.6%) acute lead related complications (perforation, microdislodgment, and macrodislodgment), three of which led to early reoperation. Over a follow-up time of up to 2.7 years (median 9.4 months), there were six (8.3%) chronic lead related complications but no failures of lead material. Most of these complications developed during the first month, and half of them were transient, with documented improvement later. Two patients (2.8%) required reoperation for chronic complications. At follow-up examination of the pacing thresholds, usually performed about 3 months after implantation, 14.3% of the examined patients had high pacing thresholds necessitating high-output programming. The mechanisms and later evolution of this phenomenon should be further evaluated.

Clinical surveillance of an active fixation, bipolar, polyurethane insulated pacing lead, Part I: The atrial lead

Since 1989, 168 Telectronics model 330-801 active fixation, polyurethane insulated atrial leads (Accufix) have been implanted at the Mayo Clinic. There were four (2.4%) acute lead related complications, (i.e., perforation, microdislodgment, and pericarditis). Over a median follow-up time of 7.6 months (up to 2.7 years), there were 14 (8.3%) chronic complications, including 1 instance (0.6%) of definite lead failure. Most of these complications were early (within the first month) and transient. Four patients (2.4%) required reoperation for chronic complications. During follow-up, 23% of the examined patients had high pacing thresholds, most at about 3 months after implantation, necessitating high-output programming. The exact mechanism and natural history of this phenomenon should be further investigated.

Long-term performance of endocardial pacing leads

To assess the performance of endocardial pacemaker leads and to identify factors associated with structural lead failure, medical records of 2,611 endocardial pacing leads (in 1,518 patients) implanted between 1980 and 1991, having at least 1 month of follow-up, were reviewed. Leads without structural failure had normal function at the last follow-up date, or were discontinued for reasons other than structural failure (patient death, infection, dislodgment, lead-pacemaker incompatibility, operative complication, or abandonment by telemetry not related to failure). Leads with suspected structural failures were invasively or noninvasively disconnected because of clinical malfunction (loss of capture or sensing, oversensing, elevated thresholds, or skeletal muscular stimulation). Leads with verified structural failures met the criteria for suspected lead failure and also had a visible defect seen in the operating room or on chest roentgenograms, a change in the impedance interpreted by the physician as lead disruption, or a manufacturer's return product report that confirmed structural failure. Variables analyzed included patients' age and gender, paced chamber, venous access, insulation materials, fixation mechanism, coaxial design, polarity, and different lead models. The cumulative lead survival at 5 and 10 years were 97.4% and 92.9%, respectively, for suspected failures; and 98.7% and 97.3%, respectively, for verified failures. Leads in older patients (> or = 65 years old), and leads in atrial position had fewer verified failures (P = 0.014 and P = 0.007, respectively). Unipolar leads also tended to perform better according to the verified definition (P = 0.07).(ABSTRACT TRUNCATED AT 250 WORDS)

Sensing/pacing lead complications with a newer generation implantable cardioverter-defibrillator: worldwide experience from the Guardian ATP 4210 clinical trial

OBJECTIVES

This report describes the sensing/pacing lead complications that developed during a worldwide clinical trial of a new implantable cardioverter-defibrillator.

BACKGROUND

The reliability of the leads used for sensing and pacing with the implantable cardioverter-defibrillator has not been adequately studied.

METHODS

The Guardian ATP 4210 was implanted in 302 patients. The sensing/pacing leads consisted of either two unipolar epicardial electrodes or a bipolar endocardial electrode from a variety of manufacturers.

RESULTS

During a mean follow-up period of 380 days, 39 patients (12.9%) required reoperation because their device developed sensing/pacing lead system complications. The most common clinical presentation was device oversensing (multiple tachycardia or noise detections or inappropriate shocks), which was observed in 27 patients, whereas elevated pacing thresholds were seen in 10 patients. Forty-one (11.8%) of 347 implanted lead systems required revision. The mean time to revision was 156 +/- 145 days. Actuarial lead survival rate at 1 and 3 years was 89% and 79%, respectively. Epicardial lead systems required significantly (p < 0.05) more revision than did endocardial systems, but when adapter problems were excluded, the revision rates of epicardial and endocardial leads were similar. Causes of lead system failures included adapter connection problems, lead dislodgement and insulation disruption. Predictors of lead revision were use of an epicardial lead system or an adapter.

CONCLUSIONS

A high rate of sensing/pacing lead complications was found with this newer generation implantable cardioverter-defibrillator. The enhanced diagnostic and data storage capabilities of this implantable cardioverter-defibrillator facilitated the recognition and troubleshooting of these complications. These findings emphasize the need for careful surveillance and testing of implantable cardioverter-defibrillator sensing/pacing leads during follow-up.