Long-term follow up of ventricular endocardial pacing leads. Complications, electrical performance, and longevity of 561 right ventricular leads

Insulation break of the ventricular lead in a dog with a pacemaker

A 10-year-old female spayed mixed breed dog that had a transvenous pacemaker implanted four years prior was presented for the evaluation of episodes of transient loss of consciousness without any history of trauma that were unresponsive to anticonvulsant therapies. Intermittent failure to capture coupled with low impedance and high capture threshold were noted upon interrogation of the pacemaker. Radiography and fluoroscopy demonstrated a possible break in the insulation of the lead. After the placement of another transvenous pacemaker, the dog had no additional syncopal episodes, and anticonvulsants were tapered off. The dog developed an implant infection from the newly placed pacemaker, which prompted the removal of the infected pacemaker and the implantation of an epicardial pacemaker. However, the epicardial lead dislodged seven days after placement, and the dog was euthanized. During necropsy, the first transvenous lead was removed, and the insulation break was visually confirmed. Although an insulation break is a rare delayed complication of pacemaker implantation, this report shows how the diagnosis, suspected by typical interrogation findings, can be aided by radiographic and fluoroscopic investigations.

Late unexpected complete fracture of a right ventricular lead still capturing the myocardium

A 72-year-old man presented for routine dual chamber pacemaker interrogation 13 years following insertion for sick sinus syndrome. Increased noise, impedance and threshold of the right ventricular (RV) lead were identified. RV capture was maintained with an overall RV pacing burden of 47%. A routine generator replacement was scheduled alongside RV lead replacement. Fluoroscopy at the start of the procedure revealed an unexpected striking fracture of the RV pacing lead with complete separation of the proximal and distal portions within the RV. The patient was asymptomatic and described no predisposing factors. He underwent implantation of a new ventricular lead and generator and has remained well. This case demonstrates clear RV lead fracture as a late complication of pacemaker implantation despite maintained capture. This emphasises the need for a chest X-ray when a change in device parameters is noted at device interrogation even in the absence of symptoms.

The New Surface Landmarks for Blind Axillary Vein Puncture

Objective

To compare the efficacy of blind axillary vein puncture utilizing the new surface landmarks for the subclavian method.

Methods

This prospective and randomized study was performed at two cardiology medical centers in East China. Five hundred thirty-eight patients indicated to undergo left-sided pacemaker or implantable cardioverter defibrillator implantation were enrolled, 272 patients under the axillary access and 266 patients under the subclavian approach. A new superficial landmark was used for the axillary venous approach, whereas conventional landmarks were used for the subclavian venous approach. We measured lead placement time and X-ray time from vein puncture until all leads were placed in superior vena cava. Meanwhile, the rate of success of lead placement and the type and incidence of complications were compared between the two groups.

Results

There were no significant differences between the two groups in baseline characteristics or number of leads implanted. There were high success rates for both strategies (98.6% [494/501] vs. 98.4% [479/487], P=0.752) and similar complication rates (14% [38/272] vs. 15% [40/266], P=0.702). Six cases in the control group developed subclavian venous crush syndrome and five had pneumothorax, while neither pneumothorax nor subclavian venous crush syndrome was observed in the experimental group.

Conclusion

We have developed a new blind approach to cannulate the axillary vein, which is as effective as the subclavian access, safer than that, and also allows to get this vein without the guidance of fluoroscopy, contrast, or echography.

Vein Management for Cardiac Device Implantation

Transvenous approaches for pacemaker and defibrillator lead insertion offer numerous advantages over epicardial techniques. Although the cephalic, axillary, and subclavian veins are most commonly used in clinical practice, they each offer their own set of advantages and disadvantages that leave their usage dependent on patient anatomy and physician preference. Alternative methods using the upper and lower venous circulation have been described when these veins are not available or practical for lead insertion. Until current technology is superseded by leadless pacing systems, the search for the optimal lead insertion technique continues.

Mechanical fatigue resistance of an implantable branched lead system for a distributed set of longitudinal intrafascicular electrodes

OBJECTIVE

A neural interface system has been developed that consists of an implantable stimulator/recorder can with a 15-electrode lead that trifurcates into three bundles of five individual wire longitudinal intrafascicular electrodes. This work evaluated the mechanical fatigue resistance of the branched lead and distributed electrode system under conditions designed to mimic anticipated strain profiles that would be observed after implantation in the human upper arm.

APPROACH

Custom test setups and procedures were developed to apply linear or angular strain at four critical stress riser points on the lead and electrode system. Each test was performed to evaluate fatigue under a high repetition/low amplitude paradigm designed to test the effects of arm movement on the leads during activities such as walking, or under a low repetition/high amplitude paradigm designed to test the effects of more strenuous upper arm activities. The tests were performed on representative samples of the implantable lead system for human use. The specimens were fabricated using procedures equivalent to those that will be used during production of human-use implants. Electrical and visual inspections of all test specimens were performed before and after the testing procedures to assess lead integrity.

MAIN RESULTS

Measurements obtained before and after applying repetitive strain indicated that all test specimens retained electrical continuity and that electrical impedance remained well below pre-specified thresholds for detection of breakage. Visual inspection under a microscope at 10×  magnification did not reveal any signs of damage to the wires or silicone sheathing at the stress riser points.

SIGNIFICANCE

These results demonstrate that the branched lead of this implantable neural interface system has sufficient mechanical fatigue resistance to withstand strain profiles anticipated when the system is implanted in an arm. The novel test setups and paradigms may be useful in testing other lead systems.

Medial subclavicular musculotendinous complex and insulation break: Rare cause of late pacemaker lead malfunction

Insulation break in a permanent pacemaker lead is a rare long-term complication. We describe an elderly male with a VVIR pacemaker, who presented with an episode of presyncope more than 3 years after the initial implantation procedure, attributed to insulation break possibly caused by lead entrapment in components of the medial subclavicular musculotendinous complex (MSMC) and repeated compressive damage over time during ipsilateral arm movement requiring lead replacement. The differential diagnosis of a clinical presentation when pacing stimuli are present with failure to capture and the role of the MSMC in causing lead damage late after implantation are discussed.

Complication rates associated with transvenous pacemaker implantation in dogs with high-grade atrioventricular block performed during versus after normal business hours

Background

Transvenous pacemaker implantation in dogs is associated with a relatively high complication rate. At our institution, pacemaker implantation in dogs with high‐grade atrioventricular block (HG‐AVB) frequently is performed as an after‐hours emergency.

Hypothesis

Among dogs with HG‐AVB, the rate of major complications is higher when pacemakers are implanted after hours (AH) compared to during business hours (BH).

Animals

Client‐owned dogs with HG‐AVB that underwent transvenous pacemaker implantation between January 2002 and December 2012 at the North Carolina State University Veterinary Teaching Hospital.

Methods

Retrospective medical record review. Two‐year follow‐up was required for complications analysis.

Results

Major complications occurred in 14/79 dogs (18%) and included lead dislodgement, lead or generator infection, lead or generator migration, and pacing failure. Incidence of major complications was significantly higher AH (10/36, 28%) compared to BH (4/43, 9%; P = .041), and all infectious complications occurred AH. Median survival time for all dogs was 27 months and did not differ between AH and BH groups for either all‐cause (P = .70) or cardiac (P = .40) mortality. AH dogs were younger than BH dogs (P = .010), but there were no other clinically relevant differences between BH and AH groups in terms of demographic, clinical, or procedural variables.

Conclusions and Clinical Importance

At our institution, AH transvenous pacemaker placement is associated with a higher rate of major complications (especially infections) compared to BH placement. This difference may be because of a variety of human factor differences AH versus BH.

Prospective study to develop surface landmarks for blind axillary vein puncture for permanent pacemaker and defibrillator lead implantation and compare it to available contrast venography guided technique

OBJECTIVE

To develop surface landmarks for blind axillary vein puncture for pacemaker lead implantation.

METHODS AND RESULTS

Patients for routine coronary angiography were counseled for participating in our study. 20 patients who gave consent were taken up for axillary venogram after proper positioning at the time of coronary angiogram. The venograms of these 20 patients, were reviewed and the landmarks were used to develop a blind axillary puncture technique. Success rate of 100% was achieved with surface landmark guided axillary vein puncture. The implantation time while using surface landmark guided axillary puncture was not significantly longer than when venography based approach was used. Another interesting observation made from the study was that increasing BMI had a positive correlation with the time taken for venous access, the fluoroscopic time and the volume of contrast used, all the associations being statistically significant. Thus, the surface landmark guided technique is more safe and expeditious in non obese patients and probably in pediatric patients as well. Moreover, the new surface landmark guided approach is a significant safety step in terms of reducing the unwanted and avoidable radiation exposure to the hands.

CONCLUSION

The results of this study demonstrate that placement of endocardial permanent pacemaker and ICD leads via the developed surface landmarks is effective and safe and is devoid of the harmful effects of radiation and contrast exposure.

High voltage lead failure diagnosed at upgrade of single-chamber ICD to dual-chamber ICD with CRT

We describe a case of defibrillation lead damage which was detected only during an upgrade procedure from single-chamber ICD to dual-chamber ICD with biventricular pacing. The damage was not detected during routine checks in the ICD clinic.

Intracardiac lead fracture in an implantable cardioverter-defibrillator

A patient with an implantable cardioverter-defibrillator (ICD) experienced inappropriate shocks. X-rays revealed that the ventricular lead was fractured at a point, which seemed to be in a mechanical stress-free space in the heart. Multiple leads were entwined making a short flexible section sandwiched between the entwined area and the stiff coil susceptible to the stress from heart beats. The present case shows that indirect concentrated stress caused by restriction of lead flexibility can result in lead fracture. Upon implanting multiple endocardial leads, attention should be given to the relative position of each lead.

Stresses from flexure in composite helical implantable leads

This study presents a theoretical model of the general stress state found in helical implantable leads in bending. The model accurately predicts stress in large filarity coils made from clad wire. The stress is predicted using flexural rigidity of the coil and is developed to include the effects of coil pitch and the relative amounts and composition of the coil materials. The results is verified using finite element models of coils made from MP35N wire and MP35N clad silver wire. The resulting model will be especially useful for the fatigue analysis and engineering design of implantable leads which are built in this manner.

Safety and effectiveness of placement of pacemaker and defibrillator leads in the axillary vein guided by contrast venography

Despite evidence of an increased incidence of lead fracture, the infraclavicular subclavian approach remains the dominant approach for placement of pacemaker and implantable defibrillator leads. Although this complication can be prevented by lead placement in the cephalic vein or by recently described approaches for lead placement in the axillary vein, these approaches have not gained widespread acceptance. The purpose of this study was to evaluate the safety and efficacy of an alternative technique for lead placement that uses contrast-guided venipuncture of the axillary vein with a 5Fr micropuncture introducer set. A total of 50 patients underwent an attempt at placement of pacemaker or implantable defibrillator leads via the axillary vein using this new technique. Patients were randomized into 2 groups based on whether the initial attempt at axillary vein access was performed medial or lateral to the rib cage margin. Lead placement was successfully accomplished in 49 of the 50 patients using this technique. Initial success was achieved in each of 25 patients randomized to the medial approach compared with 18 of 24 patients randomized to the lateral approach to the axillary vein (75%). In each of the 6 patients in whom the initial technique failed, lead placement was subsequently achieved with the medial approach. In addition to a higher initial success rate, the medial approach was determined to be preferable as evidenced by a shorter lead placement time, a smaller number of contrast injections, and a reduced requirement for additional micropuncture guidewires. There were no major complications associated with either approach. Contrast-guided venipuncture of the axillary vein is a safe and effective approach to placement of endocardial leads.

Permanent pacing system malfunction due to hidden adjacent fractures of atrial and ventricular leads

Periods of failure of ventricular pacing and atrial sensing were discovered on Holter recording in a 10-year-old boy 4 years after the implantation of a dual-chamber pacemaker with endocardial bipolar leads brought out through the right atrial wall. The old generator was explanted and the old leads tested. There was considerable atrial oversensing of an electrical artefact. The pacing threshold of ventricular lead was 1.8 V compared with 0.3 V 6 days post implantation. Post-operative lateral chest X-ray disclosed fractures of both atrial and ventricular leads at the approximate site of exit from the right atriotomy. Review of the preoperative lateral film showed that the fractures had been hidden by an ECG electrode.

Lead fracture in cephalic versus subclavian approach with transvenous implantable cardioverter defibrillator systems

Lead fracture, occurring in approximately 1%-4% of patients, is an infrequent, but potentially catastrophic complication of permanent pacing systems. Its incidence in transvenous defibrillator systems has not been established. We analyzed data from 757 patients undergoing implantation of transvenous cardioverter defibrillator systems using the Medtronic Transvene Lead system between October 20, 1989 and June 25, 1992 to determine if site of venous approach influenced incidence of lead fracture. All patients received a 3-lead system in 1 of 3 configurations: (1) right ventricle/superior vena cava/subcutaneous patch; (2) right ventricle/coronary sinus/subcutaneous patch; or (3) right ventricle/superior vena cava/coronary sinus. Of 767 right ventricular leads placed, 523 were placed via the subclavian vein, 221 via cephalic vein, and 18 via the internal jugular (5 leads were implanted using another vein). The total number of leads is greater than the total number of patients, as five patients received a second defibrillator system if the initial system was explanted and reimplanted for any reason. Seven patients (0.9%) had right ventricular lead fracture, presenting with inappropriate defibrillator shocks (1), loss of pacing ability (3), both loss of pacing ability and inappropriate shocks (1), or increased pacing threshold (2). All patients required reoperation. All had leads placed by the subclavian venous approach, with chest X ray confirming fracture at the clavicle-first rib junction in 6 of 7 cases. Using Fisher's Exact test, the difference in lead fracture between subclavian and cephalic vein implant approached statistical significance (P = 0.08). The trend toward increased lead fracture incidence with leads placed via subclavian vein suggests that cephalic vein approach may be preferable to avoid this complication.