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.     

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.     

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 (2.6%) 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.     

Comparison of Lead Complications with Polyurethane Tined, Silicone Rubber Tined, and Wedge Tip Leads: Clinical Experience with 822 Ventricular Endocardial Leads

Lead-related complications have been prospectively studied for 602 unipolar tined endocardial ventricular pacemaker leads implanted over a five-year period. No differences were noted in overall complication rates between 238 polyurethane insulated leads (4.2%) and 364 silicone rubber insulated leads (3.6%). Comparing the total series of 602 tined leads to a retrospective survey of 220 wedge tip leads, a marked reduction in dislodgements (0.3% vs. 7.7%, P<0.001) and reoperations (2.0% vs. 15.0%, P<0.001) was found using tined leads. We conclude that tined ventricular leads are far superior to wedge tip leads with respect to lead complications.     

Large, single-center experience in transvenous coronary sinus lead extraction: procedural outcomes and predictors for mechanical dilatation

Background: The aim of this study was to evaluate procedural outcomes of coronary sinus (CS) lead extraction, focusing on predictors and need for mechanical dilatation (MD) in the event that manual traction (MT) is ineffective. Methods: The study assessed results in 145 consecutive patients (age 69 ± 10 years; 121 men)—a total of 147 CS pacing leads—who underwent transvenous CS lead removal between January 2000 and March 2010. Results: All leads but one (99%) (implantation time 29 ± 25 months) were successfully removed. MT was effective in 103 (70%), and MD was necessary in the remaining 44 (30%) procedures. In multivariate analyses, unipolar design (odds ratio [OR] 3.22, 95% confidence interval [CI] 1.43–7.7; P = 0.005) and noninfective indication (OR 4.8, 95% CI 1.8–13, P = 0.002) were independent predictors for MD (P < 0.0001), with a predictive trend for prior cardiac surgery (OR 2.2, 95% CI 0.98–5.26; P = 0.06). Five (3.4%) complex procedures required a transfemoral vein approach (TFA) or repeat procedure. No deaths occurred, and there was one major complication (0.7%), cardiac tamponade, after MT. No complication predictors were identified. Conclusions: CS leads were safely and effectively removed in nearly all patients, and 70% were removed with MT alone; 30% required MD. Preoperative predictors suggesting the need for MD or TFA were noninfective indication and unipolar lead design. Complications were rare, and there was no predictable pattern among MT or MD removal techniques. (PACE 2012; 35:215–222)     

The azygos defibrillator lead for elevated defibrillation thresholds: implant technique, lead stability, and patient series

Background: Conventional insertion of implantable cardioverter‐defibrillator (ICD) includes an evaluation of the defibrillation threshold (DFT). Implanting an ancillary defibrillation lead in the azygos vein has been introduced as a therapeutic option in patients with “high” DFT. This study reports the efficacy and stability of azygos defibrillation coils implanted for elevated DFTs. Methods: This is a retrospective review of seven consecutive patients with right and left pectoral, single‐ and dual‐chamber, and biventricular ICDs and elevated DFTs, in whom an azygos defibrillation coil was introduced. Results: Addition of an azygos defibrillator lead achieved a satisfactory safety margin during single energy defibrillation efficacy testing in four out of seven patients, with success at maximum device output in two patients. No satisfactory safety margin was achieved in the remaining patient, despite the further addition of a subcutaneous defibrillation coil. No change in lead position was observed over a mean radiographic follow‐up of 8 months. No complications were noted during a mean follow‐up of 14 months, including no deaths, and no ICD shocks. Conclusion: Implanting a defibrillation coil into the azygos vein is feasible and safe. In a majority of patients with failed defibrillation efficacy testing, adding an azygos coil achieves success on repeat testing. Therefore, this technique is one option for lowering the defibrillation threshold in patients who fail DFT testing of their ICD.     

Intravascular Lead Extraction Using Locking Stylets, Sheaths, and Other Techniques

FEARNOT, N.E., ET AL.: Intravascular Lead Extraction Using Locking Stylets, Sheaths, and Other Techniques. Septicemia necessitates extraction of chronic pacemaker leads. Using locking stylets and sheaths to extract leads via the implantation vein (subclavian, cephalic, or jugular) and maneuvering devices, sheaths, and retrieval baskets via the femoral approach, extraction of 228 leads implanted 5 days to 240 months (mean 55 months) was attempted in 136 patients (mean 62 years) at 34 institutions. In addition to septicemia (9%) and infection (39Y0), total 48%, indications included prophylaxis/replacement (40%), and other (12%). Seventy-seven leads were atrial, 151 ventricular; 147 were unipolar, 81 bipolar; 96 had silicone insulation, 127 polyurethane, 1 poly/silicone, and 2 undetermined. Fixation included tines or fins (1601, screw (401, flange (12), and other (16). One hundred and ninety-four leads were completely extracted, 19 partly extracted, and 15 not extracted. Procedural complications were: torn atrium requiring open heart repair (1), hemothorax requiring a chest tube and blood transfusions (1), subacute hemothorax requiring drainage 18 days after discharge (1), thrombosis treated by drugs (1), and myocardial avulsion without sequela (1). Important observations included the significant training required due to the large number of possible clinical variables, and the need to be prepared for life-threatening cardiovascular complications. With training, procedures done at higher volume and lower volume institutions met with similar success. Conclusion: Intravascular lead extraction is a viable technique whose benefits outweigh the risks, given the proper intensive training and open heart surgical backup, and may obviate the need for open heart surgery for lead extraction.     

Extraction of transvenous pacing and ICD leads

The emergence of pacing and implantable cardioverter-defibrillator ( ICD) systems, along with expanding indications of these devices (e.g., cardiac resynchronization therapy and sudden cardiac death prevention), increasing infection rates, and device recalls have created the need for removing and upgrading these systems due to various reasons. Removing the pulse generator of a system is generally uncomplicated. Chronically implanted transvenous leads, however, adhere to the venous endothelium and endocardial tissues over time due to fibrosis. Removal of such leads can be a significantly complex procedure requiring tools and techniques that free the lead at fibrotic binding sites. In this article, the state-of-the-art tools and techniques that provide a systematic approach to consistently and safely extract these devices will be reviewed.     

Pacing and Defibrillation Lead Exchange Without Vein Puncture

Background: During lead implantation, venous access is generally achieved by puncturing the subclavian or axillary vein. Sometimes, although rarely, after lead positioning, the lead must be changed because of its inadequate mechanical stability or poor pacing parameters. This report concerns a technique of lead exchange that avoids an additional vein puncture.
Method: The tip of the lead, that has to be replaced, is retracted from the right atrium or ventricle into the superior vena cava; the lead insulation is lanced along a few millimeters; the straight flexible tip of the guide wire is inserted between the insulation layer and the conductor of the lead. Then the lead is advanced, while the guide wire is driven in, until the tip of the guide wire is in the superior vena cava. At this point, the tip of the guide wire, gently retracted from its position, is released in the vein lumen. Subsequently, the lead is completely extracted from the vein but the guide wire is maintained inside it. A dilator with a mounted peel-away sheath is advanced over the guide wire. The lead positioning follows in the usual manner.
Results: Three (2.2%) of the 139 implanted defibrillator leads and 13 (3.3%) of the 391 pacing leads were replaced. All the procedures were successful; their mean time was 2 ± 1 minutes.
Conclusion: This technique is successful and safe in providing vein access using the previously implanted lead, thus avoiding the need to repeat the puncturing of a vein.     

Acute and Long-Term Ventricular Stimulation Thresholds with a New, Iridium Oxide-Coated Electrode

Efforts have been made to design electrodes that significantly reduce not only the acute and chronic stimulation thresholds, but also attenuate the early peaking phenomenon and polarization. At two voltage levels (2.7 V and 5.4 V, respectively), we evaluated the right ventricular stimulation thresholds obtained with a new, iridium oxide-coated electrode in ten patients who received a VVI pacemaker. Measurements were mode at implant and at multiple intervals for 1 year. Pulse width stimulation thresholds at implant were as follow: 0.04 ± 0.008 msec at 2.7 V, 0.03 ± 0.004 msec at 5.4 V; values at 2 weeks were 0.14 ± 0.06 msec at 2.7 V, 0.07 ± 0.025 msec at 5.4 V; values at 3 months were 0.09 ± 0.03 msec at 2.7 V, 0.05 ± 0.01 msec at 5.4 V; values at 1 year were 0.08 ± 0.02 msec at 2.7 V, 0.04 ± 0.01 msec at 5.4 V, The maximal increase of 0.11 ± 0.05 msec occurred at 2.7 V, 2 weeks after implant. Our results indicate that this new electrode provides low acute and long-term stimulation thresholds, as well as an attenuated early peaking phenomenon, being able to stimulate safely at 2.7 V even early after implant.     

Achieving Permanent Left Ventricular Pacing—Options and Choice

Cardiac resynchronization therapy (CRT) requires permanent left ventricular (LV) pacing. Coronary sinus (CS) lead placement is the first line clinical approach but can be difficult or impossible; may suffer from a high LV pacing threshold, phrenic nerve stimulation, and dislodgement; and produces epicardial LV pacing, which is less physiological and hemodynamically effective and potentially more proarrhythmic than endocardial LV pacing. CS leads can usually be extracted with direct traction but may require use of extraction sheaths. Half of CS side branches previously used for lead placement may be unusable for the same purpose after successful lead extraction, and 30% of CS lead reimplantation attempts may fail due to exhaustion of side branches. Surgical epicardial LV lead placement is the more invasive second line approach, produces epicardial LV pacing, and has a lead failure rate of ≈15% in 5 years. Transseptal endocardial LV lead placement is the third line approach, can be difficult to achieve, but produces endocardial LV pacing. The major concern with transseptal endocardial LV leads is systemic thromboembolism, but the risk is unknown and oral anticoagulation is advised. Among the new CRT recipients in the United States and Western Europe between 2003 and 2007, 22,798 patients may require CS lead revisions, 9,119 patients may have no usable side branches for CS lead replacement, and 1,800 patients may require surgical epicardial LV lead revision in the next 5 years. The CRT community should actively explore and develop alternative approaches to LV pacing to meet this anticipated clinical demand.     

Experimental and Clinical Study of a New Permanent Myocardial Atrial Sutureless Pacing Lead

A new permanent lead has been developed for atrial epicardial use. Early clinical evaluation (26 human implants) following thorough canine studies indicates that the new lead is safe, effective, and reliable. Canine thresholds and P-wave amplitudes as a function of implant time are similar to those of transvenous alrial "J" leads. Human thresholds at implant are higher than canine, but change less with time. Implant and acute repositioning were found to be easy. There have been no lead-related operations.     

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.     

Time Course of Transvenous Pacemaker Stimulation Impedance, Capture Threshold, and Electrogram Amplitude

To examine the time course of atrial and ventricular stimulation impedance, capture threshold, and electrogram amplitude, we obtained noninvasive telemetric data in 63 patients who underwent implantation of unipolar, endocardial pacing leads and a second-generation dual chamber pacemaker with expanded bidirectional telemetry, including stimulation impedance, endocardial electrograms, and automatic capture threshold determination. On follow-up of 9-20 months (mean, 15 months), all but six patients continued to pace in the DDD mode. To validate measurements made with telemetry, invasive measurements made directly with a pacing system analyzer at time of implant were compared with immediate postimplant telemetric measurements. Significant correlation of acute stimulation impedance was noted in both atrial (r = .7, p less than .001) and ventricular (r = .8, p less than .001) lead systems. The atrial stimulation impedance decreased from 538 ohms at implant to 471 ohms at 13 months (p less than .01); the ventricular stimulation impedance similarly declined from 545 ohms to 485 ohms at 13 months (p less than .01). Capture thresholds peaked at one month, then declined: atrial, 1.2 V at implant vs 2.2 V at 1 month (p less than .008) and 1.4 V at 13 months; ventricular, 1.1 V at implant vs 1.9 V at 1 month (p less than .001) and 1.3 V at 13 months. There were no significant changes noted in atrial or ventricular electrogram amplitude following implantation. We conclude that there is close correlation of invasive recordings with those made telemetrically with this pacemaker at time of implant.(ABSTRACT TRUNCATED AT 250 WORDS)     

Two‐year extractability of novel left ventricular,active fixation leads in the sheep model

1 Background

A cardiac lead with a side helix for active fixation to the coronary vein wall (Attain Stability^®, Model 20066, Medtronic, Minneapolis, MN, USA) recently received CE Mark. The lead is designed to improve left ventricular (LV) placement and reduce dislodgement rates. The extractability of this active fixation LV lead has not been studied extensively.

2 Methods

Seventeen sheep were implanted with either an LV lead with a side helix (Model 20066, Model 20096, Medtronic) or a unipolar LV lead (Model 4193, Medtronic) as a control. Leads were extracted at approximately 26, 52, or 118 weeks. Standard extraction methodology was employed with quantitative traction up to 907 g (2 lbs.) using a locking stylet. Gross pathology and histology of the heart with particular attention to the lead tracts were performed.

3 Results

All leads were successfully removed in their entirety and required significantly less than 1 kg of traction force. The side helix disengaged from the vein as designed and resulted in no complications. No cardiac tissue was observed on any extracted lead. Gross pathology and histology were devoid of any helix‐induced lesions in the vascular structures. The epicardium over the side helix was normal and the fibrotic reaction around the helix was not significantly different from that around the nonhelix portions of the study leads or the control lead.

4 Conclusion

Extraction of the side helix, active fixation LV lead from the coronary veins in the sheep model is safe, without procedural complexity, and free of complications after long‐term LV lead implant duration.