Oversensing in a Cardioverter Defibrillator System Caused by Interaction Between Two Endocardial Defibrillation Leads in the Right Ventricle

A 53-year-old male patient underwent implantable Cardioverter defibrillator (ICD) implantation with a single lead (Endotak ®) transvenous system due to recurrent episodes of drug refractory ventricular tachycardia. After pulse generator replacement, inappropriate ICD shocks were observed due to muscle potential sensing. Intraoperatively, the old Endotak ® lead could not be extracted; therefore, it was transsected and capped. A new lead was inserted and tested without any problems. At the predischarge test, VF was induced and was followed by ICD shocks during sinus rhythm. In another surgical procedure, the old Endotak ® lead was explanted using a special instrument. The present report demonstrates that two endocardial Endotak ® leads should be avoided, because the leads may disturb each other and be followed by inappropriate ICD discharges.     

Unusual pacing observed in a biventricular pacemaker with epicardial pacing leads

In this case report, we describe inappropriate pacing in a patient with a newly implanted biventricular pacing system with three epicardial leads. Very high pacing thresholds resulted from the use of nonsteroid eluting leads, and unusual pacing behavior was due to the chosen implant locations for the right atrial and right ventricular epicardial leads. The interplay between the programmed pacemaker parameters, the very late ventricular sensing in the setting of intrinsic right bundle branch block, and atrial lead oversensing led to ineffective biventricular pacing. The persistently elevated pacing thresholds and sensing problems led to very early battery depletion and the need to replace the epicardial system with three new endocardial leads.     

Electromagnetic Interference from a Muscle Stimulation Device Causing Discharge of an Implantable Cardioverter Defibrillator: Epicardial Bipolar and Endocardial Bipolar Sensing Circuits Are Compared

This case report is about two patients with two different types of ICDs who underwent electrical muscle stimulation (EMS) therapy. In one patient with an ICD that has epicardial screw-in bipolar sensing leads, electromagnetic interference (EMI) from the EMS device caused the delivery of an inappropriate ICD discharge. In a second patient with an ICD with endocardial true bipolar sensing, there was no evidence of EMI during the EMS therapy despite all of our attempts to reproduce it. The sensing circuits in the two different ICDs are compared.     

Initial experience with an active-fixation defibrillation electrode and the presence of nonphysiological sensing

Nonphysiological sensing by a pacing and defibrillation electrode may result in inappropriate defibrillator discharges and/or inhibition of pacing. Active-fixation electrodes may be more likely to sense diaphragmatic myopotentials because of the protrusion of the screw for fixation. In addition, the movement of the fixation screw in an integrated bipolar lead system could also result in inappropriate sensing. This may be increasingly important in patients who are pacemaker dependent because the dynamic range of the autogain feature of these devices is much more narrow. Five of 15 consecutive patients who received a CPI model 0154 or 0155 active-fixation defibrillation electrode with an ICD system (CPI Ventak A V3DR model 1831 or CPI Ventak VR model 1774 defibrillator) are described. In 2 of the 15 patients, nonphysiological sensing appearing to be diaphragmatic myopotentials resulted in inappropriate defibrillator discharges. Both patients were pacemaker dependent. Changes in the sensitivity from nominal to less sensitive prevented inappropriate discharges. In one patient, discreet nonphysiological sensed events with the electrogram suggestive of ventricular activation was noted at the time of implantation. This was completely eliminated by redeployment of the active-fixation lead in the interventricular septum. In two other patients, discreet nonphysiological sensed events resulted in intermittent inhibition of ventricular pacing after implantation. These were still seen in the least sensitive autogain mode for ventricular amplitude. These were not seen on subsequent interrogation 1 month after implantation. Increased awareness of nonphysiological sensing is recommended. The CPI 0154 and 0155 leads seem to be particularly prone to this abnormality. Particular attention should be made when deploying an active-fixation screw for an integrated bipolar lead. This increased awareness is more important when a given individual is pacemaker dependent, which may warrant DFT testing in a least or less sensitive mode in these patients.     

Electromagnetic Interference by Transcutaneous Neuromuscular Electrical Stimulation in Patients with Bipolar Sensing Implantable Cardioverter Defibrillators:

CREVENNA, R., et al .: Electromagnetic Interference by Transcutaneous Neuromuscular Electrical Stimulation in Patients with Bipolar Sensing Implantable Cardioverter Defibrillators: A Pilot Safety Study. Neuromuscular electrical stimulation (NMES) is a frequently applied therapy for the treatment of pain and a therapeutic option to increase thigh muscle strength and endurance capacity in patients with heart failure. Electromagnetic interference (EMI) by the signals with sensing of ICDs is possible. Eight patients with subpectoral ICD systems and different transvenous bipolar sensing leads were subjected to electrical stimulation of the neck and shoulder and of the thighs using different stimulation algorithms. EMI with ventricular sensing was detectable in three of eight subjects. EMI occurred during stimulation of the neck (   n = 2   ) and thigh (   n = 2   ). EMI by NMES with atrial sensing was seen in two of four subjects with dual chamber ICDs. The safety of peripheral NMES has to be individually tested as EMI can also occur in ICD patients with bipolar sensing. (PACE 2003; 26[Pt. I]:626–629)     

Transvenous cardioverter defibrillator lead malfunction due to terminal connector damage in pectoral implants

Lead failure places patients with implantable cardioverter defibrillators (ICD) at risk for sudden cardiac death or results in delivery of inappropriate shocks. This study describes a mechanism of lead malfunction occurring at the junction of the terminal ring with the conductor coil of the rate sensing terminal connector in one specific model of a transvenous ICD lead. We detected the problem in a population of 179 patients with a mean age of 61 +/- 10 years and a mean lead implant duration of 16 +/- 11 months. All patients underwent pectoral ICD implantation using a submuscular approach. The implanting physician chose to place the ICD on the left side in 155 patients (87%) and on the right side in 24 patients (13%). Cephalic vein cutdown provided central venous access in 147 patients (82%), and subclavian vein puncture provided access in 32 patients (18%). Follow-up examination detected lead failure in six patients (3.5% over 31 months) due to insulation damage with or without conductor coil fracture at the junction of the terminal ring and conductor coil of the IS-1 rate sense terminal. We detected lead disruption 17 +/- 9 months (range 5-31 months) after implantation. Multiple nonsustained arrhythmia episodes exhibiting nonphysiologic intervals associated with noisy rate sensing electrograms during pocket manipulation led to discovery in three patients. The other three patients presented with inappropriate device discharges confirmed by stored high-energy lead electrograms showing normal rhythm. Pacing lead impedance abnormally dropped in two patients. Impedance remained stable in the other four patients. In conclusion, the generator pocket represents an important site of ICD transvenous lead vulnerability. Lead failure may result from conductor coil and/or insulation disruption at the interface with the rate sensing terminal connector.     

Decrease in Canine Endocardial and Epicardial Electrogram Voltages with Exercise: Implications for Pacemaker Sensing

Individuals with permanently implanted pacemakers who have normal sensing and pacing at rest may demonstrate abnormalities, particularly of atrial sensing, with exercise. Exercise is known to cause changes in the surface electrocardiographic voltages. The purpose of this study was to evaluate changes in endocardial and epicardial voltages during exercise in canines with permanently implanted pacing leads similar to those permanently implanted in humans with pacemakers. Six adult mongrel dogs were equipped with transvenous atrial and ventricular endocardial bipolar screw-in leads from a jugular venosection, and with atrial and ventricular bipolar stab-on leads from a left thoracotomy. Exercise was performed at one week following implantation and at weekly intervals for a total of 4 weeks. The animals were studied at rest and at a single workload of 3 miles per hour at a 30% elevation. Unfiltered electrograms were recorded with a VR-12 Electronics-for-Medicine photographic recorder. The mean decreases of electrograms with exercise from resting voltage were: 15% for atrial endocardial unipolar leads; 11% for atrial endocardial bipolar leads; 4% for atrial epicardial unipolar leads; 15% for atrial epicardial bipolar leads; 8% for ventricular endocardial unipolar leads; 18% for ventricular endocardial bipolar leads; 0.1% for ventricular epicardial unipolar leads and 5% for ventricular epicardial bipolar leads.     

Incidence of ICD Lead Related Complications During Long-Term Follow-Up: Comparison of Epicardial and Endocardial Electrode Systems

The aim of this study was to evaluate the longterm stability of epicardial and endocardial lead systems for third-generation cardioverter defibrillators (ICDs) and to assess the usefulness of diagnostic tools. One hundred forty patients with 61 epicardial (43.6%) and 79 nonthoracotomy systems (56.4%) were followed for 2 5 ± 19 months. A total of 18 (12.9%) lead related complications were documented. Complications of epicardial systems were detected in 10 patients (16.4%) during a follow-up time of 36 ± 8 months: crinkling of patch electrodes in 6 patients (9.8%), insulation breakage of sensing electrodes in 2 patients (3.3%), and adapter defect in 2 patients (3.3%). Eight of the patients (10.1%) with transvenous-subcutaneous systems had lead related complications during a 13 ± 6 months follow-up: fracture of the subcutaneous patch lead in 2 patients (2.5%), dislodgment of the right ventricular lead in 2 patients (2.5%), dislodgment of the superior vena cava lead in 2 patients (2.5%), insulation breakage of sensing electrodes in 1 patient (1.3%), and connector defect in 1 patient (1.3%). There was no significant difference in the incidence of lead related complications between epicardial and endocardial systems (P > 0.05). Fractures, dislodgments, and crinklings were documented within the first 8 ± 5 months by regular chest X ray. Defects of insulation, adapter, or connector were detected 22 ± 10 months after implantation and were associated with delivery of multiple inappropriate ICD therapies. An operative lead revision was indicated for 4 epicardial (6.6%) and 6 endocardial (7.6%) lead systems. Conclusions: Endocardial lead systems offer a similar long-term stability as compared to epicardial had systems. Chest X ray is the most useful tool to detect lead fracture, dislodgment. and patch crinkling. Marker recordings or real-time electrograms have not been helpful in this series to identify patients with suspected lead defects prior to the experience of inappropriate ICD discharges.     

Lead interaction: rare cause of oversensing during implantation procedure of implantable cardioverter-defibrillator system

A variety of etiologies can cause erroneous detection in patients with implantable cardioverter defibrillator (ICDs). Interaction between two endocardial leads is rare and uncommon in causing electrical noise. During a reimplantation procedure of an ICD system in a 68-year-old man, additional electrical signals could be detected. The interaction between two endocardial defibrillation leads was identified as the cause of sensing problems. When it is not possible to extract the nonfunctional endocardial lead during implantation of the new electrode, it should be implanted away and not in parallel from the old one to avoid interaction between them. A variety of etiologies can cause erroneous detection in patiens with ICD. Interaction between two endocardial leads is rare and uncommon to cause electrical noise.     

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.     

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, 5W 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 (≥ 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). The lead Medtronic 4012 had more suspected (P < 0.05) and more verified failures (P < 0.01), the lead CPI 4010 had more verified failures (P < 0.05) than the entire group of ventricular leads. Conclusions: Endocardial pacing leads implanted in atrial position, and implanted in older patients (> 65 years old) seems to have better long-term survival. Some lead models (Medtronic 4012 and CPI 4010) had poor survival rates, that could not be explained by the analyzed variables. The expected performance of endocardial pacing leads varies according to how failure is defined.     

Endocardial atrial pacing lead implantation and midterm follow-up in young patients with sinus node dysfunction after the fontan procedure

The purpose of the study was to investigate the results of endocardial lead implantation, lead performance, and follow-up in young patients after the Fontan procedure. A retrospective study was conducted with patients who had endocardial atrial pacing for SND and intact AVN function after Fontan from two pediatric centers. Patient demographics, pacing, and sensing data of endocardial atrial leads were analyzed at the time of pacemaker implantation and follow-up visits. Fifteen patients (weight 42.6 +/- 35 kg) had transvenous endocardial atrial lead implantation at an average age of 11.4 +/- 6.5 years. Active-fixation leads were used in all patients and steroid elution was present in 12 (80%) patients. Adequate P wave sensing was obtained in patients with sinus rhythm (n = 10); the remaining four patients had junctional rhythm without measurable P waves. Lead failure was not observed in any patient during the follow-up period of 2.9 +/- 2.1 years. The energy threshold at implantation was 1.46 +/- 1.5 microJ, 1.54 +/- 0.75 microJ at 3 months, 0.62 +/- 0.45 microJ at 1 year, 0.72 +/- 0.65 microJ at 2 years, 0.75 +/- 0.55 microJ at 3 years, and 0.8 +/- 0.85 microJ at 5 years postimplant. The lead impedance was 648 +/- 298 omega at implantation, 714 +/- 163 omega at 3 months, 744 +/- 195 omega at 1 year, 734 +/- 198 omega at 2 years, 800 +/- 142 omega at 3 years and 830 +/- 200 omega 5 years postimplant. Anticoagulation therapy (aspirin n = 5, warfarin n = 8) was continued by 13 patients. Complications consisted of a pneumothorax at implantation and a transient ischemic attack in one patient 4 years after pacemaker implant. Endocardial atrial leads offer low energy thresholds and can be implanted relatively safely in Fontan patients.     

Filter Characteristics of the Atrial Sensing Circuit of a Rate Responsive Pacemaker. To See or Not to See

The intra-atrial electrograms (P waves) from floating orthogonal atrial electrodes of acutely implanted pacemaker leads (SRT lead) were recorded and the frequency characteristics were determined. The atrial sensing properties of the rate responsive pacemaker (RS4) used in conjunction with these leads, were studied in relation to the frequency spectra of atrial electrograms. Whereas the P waves showed a bandwidth to 65 Hz, the filter had an upper cutoff frequency of 35 Hz. We conclude that unreliable atrial sensing with the RS4-SRT pacing system is primarily due to an inappropriate filter match and therefore no satisfactory rate responsiveness is achieved.     

Long-Term Performance of Epimyocardial Pacing Leads in Adults: Comparison with Endocardial Leads

The long-term performance of epimyocardiaJ pacing leads in children is well established, but few studies have analyzed the performance in adults. This issue has clinical relevance in view of the increased use of epimyocardial leads with implantable cardioverter defibrillator and antitachycardia pacing systems. We analyzed 93 epimyocardial pacing "systems" (121 leads: 65 unipolar, 28 bipolar) in adult patients (age 57 ± 16 years), implanted since January 1980. Two different models were studied: Medtronic 4951 "Stab–on" (n = 35) and Medtronic 6917/6917A "Screw-in" (n = 58). A control group was created by randomly matching each epimyocardial system with two endocardial leads, according to age and year of implant. Epimyocardial and endocardial leads were followed-up for 44 ± 35 and 43 ± 35 months, respectively (P = NS). Freedom from failure for epimyocardial leads was 0.91 (95% Confidence Interval [95% CI] = 0.82 to 0.96) at 5 years, and 0.91 f95% CI = 0.69 to 0.98) at 10 years. No difference was found between the two analyzed models. Freedom from failure for endocardial leads was 0.97 (95% CI = 0.93 to 0.99) and 0.90 (95% CI = 0.61 to 0.97) at 5 and 10 years, respectively. Epimyocardial Jeads had a significantly poorer short-term survival than endocardiaJ leads, secondarily to earlier "technique related" failures (P = 0.03; relative riskc 3.0; Wilcoxon test). However, overall long-term performance was similar to endocardial leads. Epimyocardial pacing leads, meticulously implanted and tested, have a long-term performance similar to endocardial pacing leads.     

Inappropriate shock delivery due to ventricular double detection with a biventricular pacing implantable cardioverter defibrillator

This report describes a patient with advanced heart failure, pronounced intraventricular conduction delay, and ventricular tachycardias who underwent implantation of a multisite pacing ICD. Pacing leads were placed in the right atrium, right ventricular apex, and to the left ventricular posterior wall via a coronary sinus vein. The system proved to have correct sensing and pacing function in an atrial synchronized biventricular pacing mode and an appropriate detection of ventricular fibrillation. However, 1 month after implantation the patient received an inappropriate shock delivery due to double detection of ventricular premature beats. The inherent detection problem of dual ventricular sensing is discussed.     

Pseudo-fracture of Pacemaker Lead Due to Securing Suture: A Case Report

With improved pacemaker lead design and materials, complications caused by lead problems have decreased.^4,5 There have been isolated reports of leads severed by suture material but they have been rare. Presented is a case of suture-induced "pseudo-fracture" in a urethane-insulated ventricular lined endocardial lead (Medtronic Model #6971-58). No loss of capture or sensing function has been encountered eight months following initial implantation. It is felt that the softer, stronger urethane permitted compression and resulted in a radiographic suggestion of a fractured lead, but lead integrity does not seem to have compromised. Although (his may be an inconsequential radiographic finding, it could lead to an inappropriate lead removal unless it is properly interpreted. (PACE, Vol. 4, November-December, 1981)     

Defibrillation coil reversal: a rare cause of abnormal noise and inappropriate shocks

We report a rare case of inadvertent reversal of the defibrillator shock coils during generator change which then resulted in both intermittent, recurrent "noise" on both the rate sensing and the shock electrogram leads and multiple inappropriate shocks.     

Three-Year Clinical Experience with a New Endocardial Screw-In Lead with Introduction Protection for Use in the Atrium and Ventricle

There is still a high incidence of dislodgement, threshold rises, and loss of sensing with permanent transvenous endocardial leads. Atrial leads are an even greater problem and require particularly reliable methods of fixation. In March, 1976 we reported our preliminary results from animal experiments using a new transvenous screw-in lead with introduction protection. This lead differs from other screw-in models as its spiral tip is retracted in the insulating tube during insertion. For fixation purposes a torque is applied to the proximal end of the conductor coil, which is loosely positioned within the tube, and this moves the helical electrode forward. One hundred and fifty endocardial electrodes have been implanted; 127 of them in the dilated ventricle and 23 in the atrium. The technique of introducing the lead into the vein (cephalic or jugular) was the same as that for conventional leads. It was easy to manage and quite uncomplicated. The fixation features in the atrium or the ventricle were sufficiently reliable to allow some patients to go home several hours post-implant. The total working time of the leads used has been 900 months; the overall complication rate is 2%.     

Effect of Implantable Nonthoracotomy Defibrillation System on Permanent Pacemakers: An In Vitro Analysis with Clinical Implications

Implantable cardioverter defibrillation systems are capable of delivering over 700 volts, and upwards of 40 joules (J) directly to the heart. Nonthoracotomy lead (NTL) systems allow the delivery of this energy to the inside of the heart, and potentially in close proximity to the leads of an endocardial pacing system. The effect of repeated maximal energy discharges (stored energy 40 J, delivered energy 38 J), utilizing both monophasic as well as biphasic shock pulses delivered via two different configuration NTL systems on a series of Pacesetter polarity programmable present generation single, and dual chamber pacemakers was evaluated in vitro using a saline test tank. All pulse generators studied demonstrated normal function and were not reprogrammed nor adversely affected by repeated defibrillation shocks. The current induced in the leads was assessed, and shown to be as high as 1.5 amps in the proximal conductor and 1.2 amps in the distal conductor of the ventricular lead, which may cause damage at the electrode-myocardial interface, and explain some of the postshock rise in capture and sensing thresholds that have been reported with implanted pacing systems postdefibrillation.     

Inadvertent Detection of 60-Hz Alternating Current by an Implantable Cardioverter Defibrillator

LEE, S.W., et al. : Inadvertent Detection of 60-Hz Alternating Current by an Implantable Cardioverter De-fibrillator. A patient with an ICD received therapies from his ICD while exercising in an indoor swimming pool. Interrogation of the ICD revealed inappropriate detection of 60-Hz alternating current artifact and delivery of ICD therapies.