Pacemaker ventricular lead microdislodgement following a motor vehicle accident.

Pacemaker lead dislodgement can be defined as any lead position change, whether the functionality of the pacemaker is affected or not. Only dislodgements that provoke a malfunction in the pacing system, however, are clinically relevant. Lead dislodgement can be categorized as 'macro' or 'micro' dislodgement depending upon the presence of radiographic evidence. This case illustrates a case of lead microdislodgement after a low-impact motor vehicle accident. The lead tip was minimally displaced; enough to produce an increase in capture threshold and eventually loss of capture while keeping near normal lead impedance values. Review of the literature shows that ventricular lead dislodgement after a motor vehicle accident is a rare incidence and cause of pacemaker malfunction.     

The Small-Tined Pacemaker Lead—Absence of Dislodgement

The Medtronic 6961 unipolar transvenous ventricular lead has four symmetrically placed, small tines that protrude backward just proximal to the tip, and are designed to become entrapped beneath or between right ventricular trabeculae. One hundred leads were implanted. Initially, the leads were more difficult to position at the right ventricular apex as the tines tended lo anchor on intracardiac structures. This was overcome by rotating the lead. The time of negotiating the Jead from right atrium to right ventricular apex averaged 3.1 minutes for all leads. The first 20 procedures averaged 4.2 minutes and the last 20 averaged 2.1 minutes. In this latter group, 11 of the 20 passages took 60 seconds or less. Once adequate positioning was obtained, the lead was retracted using slight tension to demonstrate tip entrapment. There were no lead dislodgements. Eight deaths occurred following institution of pacing and lead dislodgement was not detected in any of these cases. Four patients had complications associated with pacing, two transient diaphragmatic pacing not requiring reoperation, one right ventricular perforation and one raised threshold with intermittent failure of pacing without lead perforation or dislodgement. Because of the absence of dislodgement, this lead appears to have significant advantages over conventional leads.     

Dislodgement of atrial lead of the CRT-D system and its migration into the pocket presenting as its absence on chest x-ray

Lead dislodgement and migration is a known complication after implantation of cardiac rhythm devices. We present a case of dislodgement of atrial lead of the CRT-D system and its migration into the device pocket. The device itself had rotated by 90 degrees but the right and left ventricular leads were not at all affected. The case is unique because the lead had coiled up and was lying behind the device in the pocket and hence was not even seen on a chest x-ray.     

Thresholds and Complications with Right Ventricular Septal Pacing Compared to Apical Pacing

Background: Right ventricular septal pacing has been proposed as an alternative to apical pacing. However, data concerning thresholds and requirement for lead repositioning with this technique are scant.
Methods: We reviewed data at implantation and follow-up of 362 consecutive recipients of the same model of active fixation lead (Medtronic 5076-58, Minneapolis, MN, USA) to avoid differences due to lead characteristics. Patients were divided into two groups according to whether the lead was positioned on the interventricular septum (n = 157) or at the right ventricular apex (n = 205). Thresholds, lead impedance, and requirement for lead repositioning were compared between groups at implantation and follow-up.
Results: There were no differences between the septal and apical groups in sensing and pacing thresholds or lead impedance, either at implantation or during a 24-month follow-up. In the septal group, the lead had to be repositioned in four patients (2.5%) due to lead dislodgement in two patients, acute threshold rise in one patient, and pericardial effusion in another patient (the lead had unintentionally been positioned on the anterior free wall in these last two patients). In the apical group, the lead had to be repositioned in eight patients (3.9%, P = 0.56) due to lead dislodgement in three patients and acute threshold rise in five patients.
Conclusions: Acute and chronic thresholds associated with septal pacing are similar to those observed with apical pacing, and risk of lead dislodgement is low. However, multiple radioscopic views must be used to avoid inadvertent positioning of the lead on the anterior free wall .     

Meta‐analysis of the incidence of lead dislodgement with conventional and leadless pacemaker systems

Introduction

Leadless cardiac pacemaker (LCP) implantation using a transcatheter was recently developed to avoid pocket‐ and lead‐related complications. Although a LCP has an active fixation mechanism using tines or a helix, LCP and lead dislodgement issues remain a major safety concern for patients. This article reviews the literature to determine the incidence of lead and LCP dislodgement.

Methods and results

A total of 18 studies which included 17,321 patients undergoing conventional single‐ or dual‐chamber pacemaker implantation and three studies which included 2,116 patients undergoing LCP device implantation were reviewed. The incidence of lead dislodgement ranged from 1% to 2.69% in individual studies with a mean of 1.63%, weighted mean of 1.71%, and median of 1.60 %. There was a relatively higher lead dislodgement rate between atrial and ventricular electrodes (odds ratio [OR], 3.56; 95% confidence interval [CI], 1.9–6.70; P  =  0.6; I²  =  0%), and between magnetic resonance imaging conditional and conventional leads (OR, 2.79; 95% CI, 1.30–5.99; P  =  0.16; I²  =  46%). The use of active fixation leads (OR, 1.06; 95% CI, 0.66–1.70; P  =  0.29; I²  =  20%) showed no significant difference in dislodgement risk compared to passive fixation leads. The incidence of LCP device dislodgement was 0%, 0.13%, and 1% in three leadless pacemaker studies.

Conclusions

The incidence rates of conventional pacemaker lead dislodgement vary in individual studies with an overall high incidence. Use of the currently available LCP systems appears to result in a lower rate of device dislodgement. This may reflect the effectiveness of this novel technology and the fixation design of LCP devices.

     

The challenge of endocardial right ventricular pacing in patients with a tricuspid annuloplasty ring and severe tricuspid regurgitation

On occasion, patients with a tricuspid annuloplasty ring may require permanent cardiac pacing. Although it is technically possible to pass a ventricular transvenous lead through a tricuspid valve with an annuloplasty ring, the procedure is complicated by considerable chamber enlargement and mechanical distortion of the tricuspid valve often with severe residual tricuspid regurgitation. Over a 25-month period, transvenous ventricular lead placement following insertion of a tricuspid annuloplasty ring was successfully performed in five patients (three women). The patient mean age was 66 years (range 55-77 years). Four cases had slow atrial fibrillation and another paroxysmal atrial fibrillation requiring His-bundle ablation. Two patients had mitral valve replacement and two aortic and mitral valve replacements. All patients had residual severe to torrential tricuspid regurgitation. Seven ventricular steroid-eluting screw-in leads were used. Single leads were used in three cases, whereas in two others, two ventricular leads were attached to a dual chamber pulse generator. Although technically difficult, ventricular lead placement was successful using standard guidewires with broad curvatures. Satisfactory acute and follow-up stimulation thresholds and sensing were obtained with the only complication being an intraoperative lead dislodgement, prompting a second ventricular lead. Successful transvenous lead placement across a tricuspid annuloplasty ring is possible.     

Failure of a Second and Third Generation Implantable Cardioverter Defibrillator to Sense Ventricular Tachycardia: Implications for Fixed-Gain Sensing Devices

Failure to sense ventricular tachycardia and/or ventricular fibrillation by implantable cardioverter defibrillators (ICDs) is rare. We report a case in which persistent undersensing of monomorphic and polymorphic ventricular tachycardia occurred with a second and third generation ICD using fixed-gain sensing. This occurred despite adequate R wave sensing during sinus rhythm. The use of an endocardial sensing lead did not correct the problem. Failure to sense ventricular tachycardia in the third generation device with fixed-gain sensing occurred late after implantation and was discovered only at follow-up electrophysiology testing of the ICD. This problem could not be corrected by reprogramming of the device, and was not related to lead dislodgement. Placement of a new device with an automatic-gain sensing algorithm and use of previously implanted epicardial leads with better sensing characteristics provided appropriate sensing of ventricular tachyarrhythmias. The case illustrates the importance of testing the sensing of all ventricular arrhythmias in patients with fixed-gain ICD's. Follow-up electrophysiology testing and evaluation of epicardial and endocardial leads may be necessary in certain cases to ensure adequate sensing of ventricular tachyarrhythmias late after implantation.     

Left ventricular lead stabilization utilizing a coronary stent

Cardiac resynchronization therapy has been recently demonstrated to have a mortality and morbidity benefit in heart failure (HF) patients with cardiac dyssynchrony. Currently, the most widely used method of left ventricular (LV) lead placement involves transvenous placement of leads via the coronary sinus (CS) and into a tributary branch. Lead dislodgement is a common cause for reoperation, and continues to be a common problem despite advances in equipment and operator techniques. We describe a case where a coronary stent was placed in a lateral branch of the CS to stabilize the lead against the vessel wall.     

Left Ventricular Transvenous Electrode Dislodgement After Mustard Repair for Transposition of the Great Arteries

An 11-year-old girl who underwent Mustard's operation for complete transposition of the great arteries in infancy, developed Mobitz type II second-degree AV block 81/2 years later. A transvenous, active fixation left ventricular lead was inserted and connected to a rate responsive pacemaker. Two years later the lead dislodged due to the child's growth. A new active fixation electrode was positioned in the left ventricle below the pulmonary valve, leaving an electrode loop in the ventricle. Such an approach may prevent lead dislodgement due to growth after intraatrial repair for transposition of the great arteries, but regular radiological or echocardiographic follow-up of lead position is recommended in these patients.     

Implantation of Double Screw-in Leads

Since 1978, 600 double screw-in leads have been implanted, 320 in the ventricle and 280 in the atrium. Four episodes of cardiac perforation, one of which was lethal, have occurred during guide-catheter insertion. The electrode is now coated with polyglycol which is blood soluble and covers the electrode hooks during introduction into the vascular system without a guide catheter. The electrode hooks are exposed and can be attached to the endocardium. Three atrial leads, 1.07% and one ventricular lead, 0.31%, have become dislodged. Total dislodgement has thus been 0.67%.     

Transvenous retrograde reposition of an atrial lead

Pacemaker lead dislodgement is one of the most undesired complications of pacemaker implantation. Repeated procedures are associated with an increased risk of complications, such as pocket infection, pneumothorax, and hematoma. We present a case who experienced dislodgement of the atrial pacemaker lead of a cardiac resynchronization therapy with defibrillator implantation device, which was corrected using a steerable ablation catheter by the transfemoral route     

Transvenous Magnetic Tip Lead System for Permanent Pacing of the Heart. A Preliminary Report

An electrode for transvenous permanent ventricular pacing equipped with a supermagnet was implanted in six dogs in the apex of the right ventricle for several weeks. As no signs of myocardial perforation occurred, the device which consists of the magnetic tip lead and an external supermagnet applied to the precordial region of the chest wall was implanted in 14 patients. The lead was introduced through the right cephalic vein in 12 patients and through the right external jugular vein in the remaining 2 patients. Threshold values were measured twice a day in 12 patients who received a Siemens-Elema Vario pacemaker 629. The average peak threshold was reached on the 11th day after implantation. No pacing failure or other signs of acute dislodgement of leads occurred during the first 30 days.     

Left ventricular endocardial pacing: a transarterial approach

INTRODUCTION: We tested the feasibility of a new technique of direct left ventricular endocardial lead placement across the aortic valve in a chronic (six month) pig model. The potential for aortic valve damage, systemic embolization, and pacing lead maturation and function within the left ventricle are unknown. METHODS: Ten minipigs were successfully implanted with a transaortic left ventricular lead (Medtronic CapSureFix, Minneapolis, MN, USA) placed in the left ventricular apex via the carotid artery. Each pig received either a polyurethane (n = 5) or silicone (n = 5) lead. Post implant each pig received clopidogrel and aspirin for seven days. After six months all surviving pigs underwent thorough necropsy. RESULTS: Each pig had adequate sensing (12.1 +/- 4 mV) and pacing thresholds (0.79 +/- 0.2 @ 0.5 V) at implant. Postoperatively two pigs died of a respiratory illness. One pig died postoperatively due to sepsis. At the six-month follow-up, all surviving pigs (n = 7) were in a healthy state. Of the pigs without dislodgement (n = 5) there was adequate sensing, but a rise in pacing thresholds. Echocardiography revealed a normal ejection fraction and only trace to mild aortic insufficiency in all pigs. Of the seven surviving pigs there were no thromboembolic events noted. One silicone lead was noted to have thrombosis along the lead screw and shaft. CONCLUSION: Direct transaortic placement of a left ventricular lead is feasible. After six months, there was no significant aortic regurgitation and no evidence of thromboembolism despite no anticoagulation. Lead function was acceptable and only one silicone lead (and no polyurethane lead) was noted to have significant thrombosis.     

Atrial programmed pacing.

Early experience with a J-shaped lead inserted transvenously into the right atrial appendage is reviewed in thirty-one patients. Fifteen patients are still being followed with satisfactory atrial programmed pacing for five to ten years. A dislodgement rate of twenty percent led to the development of the "tined" J lead in the hope that better fixation would be achieved. Experimental data has shown the new lead to be stable with evidence in both animal and man of firm fixation of the lead in the appendage. The lead has been inserted in twenty patients. Of these, fifteen are still being followed with satisfactory atrial programmed pacing. There has been no case of dislodgement of the lead in a follow-up period of two years and eight months.     

Elimination of Lead Dislodgement by the Use of Tined Transvenous Electrodes

Pacemaker lead dislodgement has accounted for a large proportion of the postoperative complications seen after transvenous pacemaker insertion. Ninety-two patients underwent implantation of a tined transvenous electrode over a three-year period without a single dislodgement. Excellent thresholds were obtained and no difficulties related to electrode insertion were encountered. Tined transvenous pacemaker leads are preferred for routine use at this time.     

Evaluation of safety and efficacy of pacemaker and defibrillator implantation by axillary incision in pediatric patients

We successfully implanted 11 pacemakers, 6 defibrillators, and 1 biventricular pacemaker in 18 pediatric patients (15 female; 4 to 15 years, average age: 9) using the retropectoral transvenous approach with a hidden axillary incision. The average follow-up period was 24 months (range 49 months). Eight patients had congenital structural heart conditions (d-transposition of great arteries S/P Mustard operation, d-transposition of great arteries S/P arterial switch operation, truncus arteriosus, right ventricular diverticula, ventricular septal defect, hypertrophic cardiomyopathy). Four patients had acquired heart conditions (dilated cardiomyopathy, myocarditis). Excellent sensing and pacing thresholds were achieved in all attempted implantations. There was no pneumothorax. There was one lead dislodgement. One lead fracture distant from the subclavian vein occurred 4 months after implantation. Implantation of pacemakers and defibrillators via axillary incisions can be safe and effective in pediatric patients. This approach avoids skin erosion when implanting large devices such as defibrillators or biventricular devices in small patients with limited muscle mass while achieving superior aesthetic results. The axillary or extrathoracic venous entry site avoids subclavian crush syndrome.     

Comparison of mid-term clinical experience with steroid-eluting active and passive fixation ventricular electrodes in children

Although active fixation ventricular leads seem to have advantages over passive fixation leads, this study compares the follow-up results of active and passive fixation leads in children. We evaluated the implantation and follow-up data of 41 children with active (Accufix II DEC, group 1) (n = 20) or passive (Membrane E, group 2) (n = 21) fixation, steroid-eluting ventricular leads. All but one of the patients in group 1 completed the 12-month follow-up. The mean follow-up period in group 2 was 10.4 +/- 2.9 months (range 3-12 months, median 12 months). In both groups the mean pacing threshold was measured as 0.51 +/- 0.09 V versus 0.48 +/- 0.15 V (P > 0.05) at 0.5-ms pulse width, mean R wave amplitude as 9.9 +/- 2.5 mV versus 9.4 +/- 3.2 mV (P > 0.05), and mean impedance as 557 +/- 92 omega versus 664 +/- 160 omega (P < 0.05), respectively, at implantation. After the first week of pacing, mean threshold values in group 1 were significantly lower than those of group 2 (P < 0.01 and P < 0.05, respectively). During the follow-up period, lead impedance measurements did not show a significant difference between the two groups. In one patient from group 1, the lead (by unscrewing) was removed easily because of pacemaker pocket infection. No lead dislodgement or helix deformation occurred in group 1. Nevertheless, in one patient from group 2, the lead was extracted at 4-month postimplantation because of lead displacement. We conclude that the steroid-eluting active fixation lead (Accufix II DEC) have advantages of easier implantation and lower acute and chronic stimulation thresholds compared to the passive fixation lead (Membrane E). Therefore, Accufix II DEC is superior to Membrane E, and it is a better first choice in children with an implanted single chamber ventricular pacemaker.     

Long-term follow-up of left ventricular pacing via a posterior cardiac vein after mechanical tricuspid valve replacement

Permanent cardiac pacing was recommended in a 66-year-old woman with mechanical prosthetic mitral and tricuspid valves. To avoid a thoracotomy, a conventional endocardial lead was inserted with a steerable stylet (Locator) into the posterior cardiac vein via the right cephalic vein. Four weeks later, lead dislodgement required reoperation. The lead position remained stable up to 29 months.     

Preliminary Experience with Nonthoracotomy Implantahle Cardioverter Defihrillators in Young Patients

Implantable cardioverter defihrillators represent an important treatment option for patients with life-threatening tachyarrhythinias. However, the requirement for surgical access to the thorax contributes to significant procedural morbidity with ICD implantation. This study was performed to assess an initial experience with a nonthoracotomy approach to ICD lead implantation in young patients. An international survey identified 17 patients, ranging in age from 12–20 years (mean = 16.7 ± 2.4) and weighing from 33–89 kg (mean = 60.6 ± 13.3), who had undergone placement of the Medtronic Transvene^R defibrillator lead system. Implant indications were aborted sudden cardiac death in 15 patients and recurrent ventricular tachycardia or familial sudden death in 2 patients. At a median follow-up of 7.9 months, 9 of 17 patients had received at least one ICD therapy. There have been no deaths. Complications included patch or generator erosion (3 patients), lead dislodgement (1 patient), and ICD system infection requiring explanation (1 patient). The initial experience with nonthoracotomy ICDs in young patients appears promising. This approach may be particularly advantageous for patients who have undergone prior thoracotomy. Prospective clinical trials will be required to establish the applicability of these lead systems to select patient populations.     

Pacemaker Clinic Evaluations: Key to Early Identification of Surgical Problems

The pacemaker center evaluation was responsible for the timely reoperation of 341 pacemaker patients over the last three years. The most common indication for reoperation was battery end-of-service (46.3%). Battery testing and maintenance of accurate records for trend analysis ensures prompt generator replacement. Atrial and/or ventricular lead malfunction was the second largest indication (26.3%). Lead malfunction detected by bracketing capture and sensing thresholds included: dislodgement, penetration, exit block, fracture, insulation failure, and abnormal sensing. The third largest indication for reoperation was pacemaker pocket erosion and/or infection (15.5%). Examination of the pacemaker pocket site is an integral part of an evaluation. In conclusion, the three largest indications for reoperations can he best demonstrated in a pacemaker center where evaluations are personal and thorough, and accurate record keeping is maintained.