Incidence of ICD lead related complications during long-term follow-up: comparison of epicardial and endocardial electrode systems

Epicardial Devices in Pediatrics and Congenital Heart Disease

Epicardial cardiac implantable electronic device implant remains a common option in pediatric patients and certain patients with congenital heart disease due to patient size, complex anatomy, residual intracardiac shunts, and prior surgery precluding transvenous implant. Advantages include the lack of thromboembolic and vascular risks and ability to implant during concomitant surgery. Significant disadvantages include the occurrence of lead dysfunction that can result in bradycardia events in pacemaker patients, inappropriate shocks in implantable cardiac defibrillator patients, and overall a more invasive procedure.

Use of implantable cardioverter-defibrillator in children supported with ventricular assist device: An analysis of data from the EUROMACS registry

BACKGROUND

Data on the use and outcome of children on ventricular assist device (VAD) support provided with an implantable cardioverter-defibrillator (ICD) remains poor.

METHODS

A retrospective analysis of the EUROMACS database on children supported with VAD < 19 years of age from January 1, 2009 to April 1, 2020. Patients with missing data on status of ICD, missing baseline and/or follow up information were excluded. The primary independent variable of interest was the concomitant presence or absence of an ICD at the time of VAD placement. Kaplan-Meier survival analysis was performed to evaluate survival differences between children on VAD with and without an ICD.

RESULTS

Out of 303 patients provided with a VAD, 7% (7♀, 15♂) had an ICD implanted and formed the study group. Median age was 14 years, median weight was 43.5 kg, and median BSA was 1.39. Median Intermacs stage was 2 (range: 1-7). Seventeen patients (77%) were transplanted, 4 (18%) died while on support, and 1 (5%) was weaned from device after myocardial recovery. Median time on support was 68 days compared to 361 days in the control group (p: 0.01). Three patients underwent device exchange due to thrombus formation in the pump. There was no difference in survival between groups (p = 0.342).

CONCLUSION

The presence of ICD in pediatric patients supported with a VAD is low (7%). Children on VAD support provided with an ICD do not have a survival benefit compared to children without an ICD.

Incidence and Clinical Predictors of Early and Late Complications of Implantable Cardioverter-Defibrillators in Adults With Congenital Heart Disease

BACKGROUND

The implantable cardioverter-defibrillator (ICD) has been proven to improve survival in adults with congenital heart disease (ACHD), but it is associated with a high rate of complications. We aimed to quantify the incidence of early (≤ 3 months; ECs) and late (> 3 months; LCs) complications in ACHD patients implanted with an ICD and to identify their clinical predictors.

METHODS

We retrospectively reviewed 207 patients who had ICD follow-up at Toronto General Hospital from 1996 to 2019.

RESULTS

The most common diagnoses were tetralogy of Fallot (32.4%), dextro-transposition of the great arteries (17.9%), and congenital corrected transposition of the great arteries (13%). No intraprocedural complications were observed. Median follow-up was 3.4 years (IQR 0.1-23). 24 patients (12%) developed EC (4 hematomas, 20 lead dislodgements). A total of 56 LCs occurred (46% lead failure, 21% infection, 11% prophylactic lead extraction, 9% neurologic pain, 9% erosion, 4% other) with an incidence rate of LCs of 18% per 5 person-years. Anatomic complexity (odds ratio 2.9; P = 0.02) and cardiac resynchronization therapy defibrillator implant (odds ratio 2.5; P = 0.04) were associated with ECs. Survival rates free from LCs were 92%, 86%, and 65%, respectively, after 1, 5, and 10 years. Presence of legacy leads (hazard ratio 2.9; P = 0.006) and subpulmonary ejection fraction (5% increase, hazard ratio 1.35; P = 0.031) were associated with LCs.

CONCLUSIONS

ACHD patients at risk of sudden cardiac death continue to benefit from newer device technology. However, these patients, particularly those with greater anatomic and device complexity, remain at increased risk of developing complications over their lifetime. Given the life expectancy of this population, careful consideration needs to be given when a device for primary prevention is being contemplated.

Completely epicardial implantable cardioverter/defibrillator (ICD) and CRT-D systems: A case series and systematic literature review

BACKGROUND

Epicardial ICD systems and CRT-Ds using high voltage coils represent an alternative to transvenous systems in patients without central venous access and prior device complications including infection.

OBJECTIVE

We present a case series in the adult population of epicardial ICD/CRTD systems using high voltage epicardial coils. We summarize the existing data regarding techniques, efficacy, and safety.

METHODS

A retrospective board approved medical record review was conducted for all patients undergoing epicardial ICD/CRTD placement at our institution between January 2010 and May 2020. The literature was reviewed for prior published trials, case reports, and case series of epicardial high voltage coil insertions.

RESULTS

Eleven patients (six female, mean age 48 years) underwent epicardial ICD/CRTD implant including 5/11 completely epicardial CRTD systems. The procedure was performed via median sternotomy in eight patients, left anterior thoracotomy in two patients, and sub-xiphoid approach in one patient. After a mean follow up of 35 months, appropriate successful shocks were delivered in two (18%) patients and no patients received an inappropriate shock. Three of five (60%) patients had volumetric remodeling with CRT with significant improvement of LV EF. Device-related complications requiring a surgical/percutaneous revision or another DFT test occurred in six patients (54%). One patient died during follow up due to refractory heart failure. No cases of epicardial device infection, coronary artery compression, constrictive pericarditis, or erosion of defibrillator coils into intrathoracic organs were reported. No randomized studies comparing safety and efficacy of traditional transvenous or subcutaneous ICD systems and epicardial ICD systems using contemporary high voltage coils were found nor any studies directly comparing epicardial defibrillator patches versus epicardial coils. Thirteen case series and 24 single case reports published between 2004 and 2020 were identified describing in total a heterogenous group of 188 patients with ICD systems incorporating one or more epi- or pericardially positioned shock coils.

CONCLUSION

The use of epicardial defibrillation coils for ICD/CRT-D is a feasible treatment option for patients with either failed or contraindicated transvenous ICD systems. Dedicated epicardial high voltage leads with integrated pace-sense electrodes and specialized delivery tools for minimal invasive implantations may improve longer term outcomes.

No light without the dark: Perspectives and hindrances for translation of cardiac optogenetics

Over the last decade, optogenetic stimulation of the heart and its translational potential for rhythm control attracted more and more interest. Optogenetics allows to stimulate cardiomyocytes expressing the light-gated cation channel Channelrhodopsin 2 (ChR2) with light and thus high spatio-temporal precision. Therefore this new approach can overcome the technical limitations of electrical stimulation. In regard of translational approaches, the prospect of pain-free stimulation, if ChR2 expression is restricted to cardiomyocytes, is especially intriguing and could be highly beneficial for cardioversion and defibrillation. However, there is no light without shadow and cardiac optogenetics has to surmount critical hurdles, namely "how" to inscribe light-sensitivity by expressing ChR2 in a native heart and how to avoid side effects such as possible immune responses against the gene transfer. Furthermore, implantable light devices have to be developed which ensure sufficient illumination in a highly contractile environment. Therefore this article reviews recent advantages in the field of cardiac optogenetics with a special focus on the hindrances for the potential translation of this new approach into clinics and provides an outlook how these have to be carefully investigated and could be solved step by step.

Should Single-Coil Implantable Cardioverter Defibrillator Leads Be Used in all Patients?

The historical preference for dual-coil implantable cardioverter defibrillator leads stems from high defibrillation thresholds associated with old device platforms. The high safety margins generated by contemporary devices have rendered the modest difference in defibrillation efficacy between single- and dual-coil leads clinically insignificant. Cohort data demonstrating worse lead extraction outcomes and higher all-cause mortality have brought the incremental utility of an superior vena cava coil into question. This article summarizes the current literature and re-evaluates the utility of dual-coil leads in the context of modern device technology.

Surgical techniques for implanting implantable cardioverter defibrillators in children and infants

Implantable cardioverter defibrillators (ICDs) are now being used in children. ICDs can be used to prevent sudden cardiac death caused by not only congenital heart defects, but also various non-structural diseases, such as long QT syndrome. However, a standard implantation technique for children, especially infants, has not yet been established. As the surgical implantation in infants is not amenable to transvenous lead placement, it was necessary to choose from epicardial, subcutaneous and pericardial ICD systems. However, many of these systems are associated with high rates of late complications. Lead fracture, insulation breakage, migration, buckling or crinkling of the patch lead and constrictive pericarditis have been reported as the most common lead-related complications. An increase in the defibrillation threshold is another issue that must be considered when using an ICD in a child or infant. Further studies on the outcomes, psychosomatic impact and other specific complications in the pediatric population need to be considered. The clinical use of ICDs in infants is still limited. Therefore, it is important to have many surgical options available so that the treatment can be custom-tailored to suit individual patients.

Finite element modeling of subcutaneous implantable defibrillator electrodes in an adult torso

BACKGROUND

Total subcutaneous implantable subcutaneous defibrillators are in development, but optimal electrode configurations are not known.

OBJECTIVE

We used image-based finite element models (FEM) to predict the myocardial electric field generated during defibrillation shocks (pseudo-DFT) in a wide variety of reported and innovative subcutaneous electrode positions to determine factors affecting optimal lead positions for subcutaneous implantable cardioverter-defibrillators (S-ICD).

METHODS

An image-based FEM of an adult man was used to predict pseudo-DFTs across a wide range of technically feasible S-ICD electrode placements. Generator location, lead location, length, geometry and orientation, and spatial relation of electrodes to ventricular mass were systematically varied. Best electrode configurations were determined, and spatial factors contributing to low pseudo-DFTs were identified using regression and general linear models.

RESULTS

A total of 122 single-electrode/array configurations and 28 dual-electrode configurations were simulated. Pseudo-DFTs for single-electrode orientations ranged from 0.60 to 16.0 (mean 2.65 +/- 2.48) times that predicted for the base case, an anterior-posterior configuration recently tested clinically. A total of 32 of 150 tested configurations (21%) had pseudo-DFT ratios </=1, indicating the possibility of multiple novel, efficient, and clinically relevant orientations. Favorable alignment of lead-generator vector with ventricular myocardium and increased lead length were the most important factors correlated with pseudo-DFT, accounting for 70% of the predicted variation (R(2) = 0.70, each factor P < .05) in a combined general linear model in which parameter estimates were calculated for each factor.

CONCLUSION

Further exploration of novel and efficient electrode configurations may be of value in the development of the S-ICD technologies and implant procedure. FEM modeling suggests that the choice of configurations that maximize shock vector alignment with the center of myocardial mass and use of longer leads is more likely to result in lower DFT.

[ICD lead defects: diagnosis and therapeutical options]

The number of cardioverter/defibrillator (ICD) implantations has been steadily increasing; thus, ICD lead-associated complications are an important issue. No clear recommendations for the diagnosis and management are available. This article gives an overview of how to diagnose and manage an ICD lead defect. Possible therapeutic options are discussed by reviewing the literature.

Postoperative ventricular tachycardia in patients with congenital heart disease: diagnosis and management

Ventricular tachycardia (VT) after palliative repair of congenital heart disease is relatively rare. Despite this rarity, VT is a known cause of early, intermediate and late morbidity and mortality in these patients. A number of factors have been linked to the development of VT in this unique patient population. The purpose of this article is to provide a concise overview regarding the etiology, diagnosis and treatment of VT in patients with congenital heart disease. In-depth information will be provided to aid diagnosis and the treatment of early postoperative VT. The use of additional diagnostic methods such as echocardiography, cardiac catheterization and electrophysiology studies to risk assess patients with postoperative VT will also be discussed. In addition, I examine the long-term management strategies for VT in these patients, from medical management and cardiovascular surgery to implantation of cardioverter-defibrillators.

Resolution of T-Wave Oversensing with Implantable Cardioverter Defibrillator Generator Replacement in an Adolescent

Inappropriate delivery of therapy due to T-wave oversensing is a frequent complication of intracardiac cardioverter defibrillators (ICD). A 16-year-old adolescent with congenital long QT syndrome type 3 underwent single-chamber implantable cardioverter defibrillator (ICD) (EnTrust VR, Medtronic Inc., Minneapolis, MN, USA) implantation.He received two appropriate and four inappropriate shocks. The inappropriate shocks were due to T-wave oversensing. Following the replacement of ICD with a different brand generator (Vitality 2 VR, Boston Scientific Inc., Natick, MA, USA), no more T-wave oversensing is noted. Proper filtering is imperative in ICDs in order to prevent T-wave oversensing-related inappropriate delivery of therapy.

Management of patients with implantable cardioverter defibrillators at emergency departments

BACKGROUND

With rapid improvements in technology and accumulation of clinical evidence, the implantable cardioverter defibrillator (ICD) has become a standard treatment for either primary or secondary prevention of sudden cardiac death. However, no analysis based on the perspective of emergency department has been reported, and managing patients with ICD remains a challenge to the emergency department doctors.

METHODS

This study reviewed the emergency department visits of patients who received ICD implantation in a single university hospital from 1995 to 2004. The baseline demographic and laboratory data were compared between groups with the non-parametric method of the Mann-Whitney U test for continuous data and the chi2 test for categorical data; p<0.05 was considered significant.

RESULTS

81 patients (56 men and 25 women) were included in this study. 43% of patients had at least one emergency department visit during the follow-up period, and a total of 86 emergency department visits were recorded. The most frequent aetiology of emergency department visits was ICD discharge (37 episodes; 43.1%) and the most frequent presenting symptom was electric shock sensation (25 episodes; 29.1%). Only 11 (12.8%) emergency department visits were because of non-cardiac aetiologies. Patients with emergency department visits had significant lower left ventricular ejection fraction (mean (SD) 41.5 (19.8) v 55.2 (18.4) ejection fraction units; p = 0.005) and more use of warfarin (8.6% v 0%; p<0.05). Although most emergency department visits were device or arrhythmia related, the acute coronary syndrome and congestive heart failure still accounted for 27.9% of hospital returns in combination.

CONCLUSIONS

Defibrillator discharge, acute coronary syndrome and heart failure constitute most aetiologies of emergency department visits of patients with ICD. The risk factors include lower left ventricular ejection fraction and use of warfarin.

Erosion of an Extrapericardial Implantable Cardioverter Defibrillator Patch Through the Gastric Fundus With Fistulous Tract Formation

Until as recently as the mid-1990s, implantable cardioverter defibrillator (ICD) leads were placed through thoracotomy as anterior and/or posterolateral patches. The defibrillator patches have reportedly been associated with a number of relatively common mechanical complications as well as less common complications, including patch migration or erosion into contiguous structures. We report a previously unreported late complication of epicardial defibrillator patch placement in which patch migration and erosion through the gastric fundus resulted in fistulous tract formation from the mediastinum to the lumen of the stomach. Although surgically implanted epicardial patch defibrillator systems are relatively uncommon in current U.S. practice, these devices are still used when specific anatomic or electrophysiological considerations preclude the use of more common endocardial lead systems. Several thousand patients with epicardial patch leads in place are still believed to be alive in the United States. In these patients, continued vigilance for lead-related complications is appropriate. Prompt surgical intervention is usually warranted when patch migration or complications such as the one described occur.

Innovative Techniques for Placement of Implantable Cardioverter-Defibrillator Leads in Patients with Limited Venous Access to the Heart

BACKGROUND

Because of venous occlusion, intracardiac shunting, previous surgery, or small size placement of implantable cardioverter-defibrillator (ICD) leads may not be possible using traditional methods. The purpose of this study was to evaluate and describe innovative methods of placing ICD leads.

METHODS

The records of all patients undergoing ICD implantation at our institution were reviewed to identify patients with nontraditional lead placement. Indications for ICD, method of lead and coil placement, defibrillation thresholds, complications, and follow-up results were reviewed retrospectively.

RESULTS

Eight patients (aged 11 months to 29 years) were identified. Six patients with limited venous access to the heart (four extracardiac Fontan, one bidirectional Glenn, one 8 kg 11-month-old) underwent surgical placement of an ICD coil directly into the pericardial sac. A second bipolar lead was placed on the ventricle for sensing and pacing. Two patients with difficult venous access had a standard transvenous ICD lead inserted directly into the right atrium (transatrial approach) and then positioned into the ventricle. All patients had a defibrillation threshold of <20 J, although one patient required placement of a second coil due to an elevated threshold. There have been no complications and two successful appropriate ICD discharges at follow-up (median 22 months, range 5-42 months).

CONCLUSIONS

Many factors may prohibit transvenous ICD lead placement. Nontraditional surgical placement of subcutaneous ICD leads on the pericardium or the use of a transatrial approach can be effective techniques in these patients. These procedures can be performed at low risk to the patient with excellent defibrillation thresholds.

Long-term experience with subcutaneous ICD leads: a comparison among three different types of subcutaneous leads

ICDs provide protection against sudden cardiac death in patients with life-threatening arrhythmias. Nevertheless, efficacy of defibrillation remains an important issue to guarantee the future safety of patients who receive an ICD. There is a significant number of patients who need an additional subcutaneous lead to obtain a defibrillation safety margin of at least 10 J between the maximum output of the ICD and the energy needed for ventricular defibrillation. However, few data exists about the long-term performance of different types of subcutaneous leads. Therefore, the aim of this study was to analyze the long-term experience with three different types of subcutaneous leads. The study included 132 patients (109 men, 23 women; mean age 59.8 years [SD +/- 10.7 years]). All of them received a subcutaneous lead in addition to a single chamber or dual chamber ICD between October 1990 and April 2002. Two patients received a second subcutaneous lead after the first lead had been removed so that a total of 134 subcutaneous leads were evaluated. Inclusion criteria for the implantation of an additional subcutaneous lead were (1) unsuccessful ventricular defibrillation at implant without a subcutaneous lead, (2) insufficient safety margin (< 10 J) between the maximum output of the ICD and the energy needed for ventricular defibrillation, or (3) clinical evaluation of a new subcutaneous lead (Medtronic 13014). There were no significant differences between the three study groups with regard to age, sex, underlying cardiac disease, left ventricular ejection fraction, NYHA class assessment and clinical arrhythmia. The results of the DFT testing during follow-up (prehospital discharge test and 1 and 3 years) were compared to the baseline value obtained during the implantation procedure. All lead related complications were analyzed. Eighty-two single element subcutaneous array electrodes (SQ-A1), 31 subcutaneous three-finger electrodes (SQ-A3), and 21 subcutaneous patch electrodes (SQ-P) were implanted during the study period. The median follow-up was 1,499 days (25th percentile: 798 days, 75th percentile: 1,976 days) in the SQ-A1 group, 2,209 days (25th percentile: 1,242 days, 75th percentile: 2,710 days) in the SQ-A3 group, and 1,419 days (25th percentile: 787 days, 75th percentile: 2,838 days) in the SQ-P group. None of the three groups had a significant change of the DFT during follow-up compared to baseline. Major complications occurred in six (7.3%) patients in group SQ-A1 and in two (9.5%) patients in group SQ-P. There were no major complications in group SQ-A3. Kaplan-Meier curves analyzing freedom from subcutaneous lead related complications did not show a significant difference between the three study groups (P = 0.16). SQ-A1, SQ-A3, and SQ-P leads provide stable DFTs during long-term follow-up. Major complications are rare. However, a careful follow-up including chest radiographs at regular intervals is needed to detect potentially fatal complications like lead fractures.

Automatic Impedance Monitoring and Patient Alert Feature in Implantable Cardioverter Defibrillators:

Recent advances in implantable cardioverter defibrillator (ICD) technology have enabled implementation of an automatic monitoring feature in ICDs that provides daily measurements of several technical parameters such as battery status, pacing, and high-voltage impedance. The system alerts the patient with an audible alarm to contact the physician in case the measured parameters are not within normal limits. Early detection of intermittent and potentially serious complications justifies routine use of this feature. This report describes a patient with an ICD who died suddenly due to ventricular fibrillation, which was not appropriately treated by the device. The cause of device malfunction was most likely an intermittent lead fracture that was not detected by the automatic impedance monitoring and alert feature of this device. Based on these data, potential benefits and theoretical pitfalls of automatic impedance monitoring and alert features are discussed.

Fracture of the Subcutaneous Patch Electrode in a Patient With an Implanted Cardioverter-Defibrillator

There are more than 20 years of experience with implantation of defibrillator devices in humans and the procedure is an important therapeutic option for patients at high risk of life-threatening ventricular arrhythmias. The incidence of new defibrillator implantation has gradually increased, being used even in children, (1) although pediatric use is associated with several complications, especially with epicardial systems,(2) including fracture of the subcutaneous patch,(3-5) mainly because of growth.(3) We present a case of subcutaneous patch electrode fracture in the left axillary pectoral region of a patient who needed the patch for effective defibrillation, and we discuss the methods of treatment.

Deaths associated with implantable cardioverter defibrillator failure and deactivation reported in the United States Food and Drug Administration Manufacturer and User Facility Device Experience Database

OBJECTIVES

The aim of this study was to understand the causes of implantable cardioverter defibrillator (ICD) failure and complications so that adverse events, including unnecessary death, can be prevented.

BACKGROUND

Sudden death may occur if an ICD fails to treat life-threatening ventricular arrhythmias.

METHODS

The United States Food and Drug Administration Manufacturer and User Facility Device Experience Database was searched for ICD devices and the search term "death." The search yielded 212 death events involving 100 ICD pulse generator and lead models from five manufacturers. These death events were associated with (A) ICD devices for which pulse generator interrogation data and/or the results of the manufacturers analysis of returned devices were available; (B) ICD devices for which neither interrogation data nor the results of the manufacturer's analysis were reported; and (C) normally functioning ICDs that had been deactivated.

RESULTS

(A) A total of 103 (69%) of 150 death events were associated with defective pulse generators or high-voltage leads. Most (34/42 [81%]) apparently sudden or arrhythmic death events were associated with high-voltage lead failure; other deaths were related to pulse generator failure (8/42 [19%]) caused by electronic component defects. (B) A total of 21 of 51 death events were related to a manufacturer's recall; all deaths were arrhythmic but without allegation of device failure. (C) Eleven death events occurred in patients whose pulse generators were found to be off or deactivated; these devices appeared to have been deactivated accidentally or by exposure to magnetic fields, or they were not reactivated after elective surgery.

CONCLUSIONS

ICD device failure and unintended pulse generator deactivation have resulted in unnecessary deaths. Although these deaths may be infrequent, improved devices and follow-up techniques are needed. The magnet deactivation feature probably is unsafe, and health professionals and patients should be cautioned.

High Incidence of Appropriate and Inappropriate ICD Therapies in Children and Adolescents with Implantable Cardioverter Defibrillator

Appropriate and inappropriate therapies of implantable cardioverter defibrillators have a major impact on morbidity and quality of life in ICD recipients, but have not been systematically studied in children and young adults during long-term follow-up. ICD implantation was performed in 20 patients at the mean age of 16 +/- 6 years, 11 of which had prior surgical repair of a congenital heart defect, 9 patients had other cardiac diseases. Implant indications were aborted sudden cardiac death in six patients, recurrent ventricular tachycardia in 9 patient, and syncope in 5 patients. Epicardial implantation was performed in 6 and transvenous implantation in 14 patients. Incidence, reasons and predictors (age, gender, repaired congenital heart disease, history of supraventricular tachycardia, and epicardial electrode system) of appropriate and inappropriate ICD therapies were analyzed during a mean follow-up period of 51 +/- 31 months range 18-132 months. There were a total 239 ICD therapies in 17 patients (85%) with a therapy rate of 2.8 per patient-years of follow-up. 127 (53%) ICD therapies in 15 (75%) patients were catagorized as appropriate and 112 (47%) therapies in 10 (50%) patients as inappropriate, with a rate of 1.5 appropriate and 1.3 inappropriate ICD therapies per patient-years of follow-up. Time to first appropriate therapy was 16 +/- 18 months. Appropriate therapies were caused by ventricular fibrillation in 29 and ventricular tachycardia in 98 episodes. Termination was successful by antitachycardia pacing in 4 (3%) and by shock therapy in 123 episodes (97%). Time to first inappropriate therapy was 16 +/- 17 months. Inappropriate therapies were caused by supraventricular tachycardia in 77 (69%), T wave oversensing in 19 (17%), and electrode defect in 16 episodes (14%). It caused shocks in 87 (78%) and only antitachycardia pacing in 25 episodes (22%). No clinical variable could be identified as predictor of either appropriate or inappropriate ICD therapies. There is a high rate of ICD therapies in young ICD recipients, the majority of which occur during early follow-up. The rate of inappropriate therapies is as high as 47% and is caused by supraventricular tachycardia and electrode complications in the majority of cases. Prospective trials are required to establish preventative strategies of ICD therapies in this young patient population.

Application of Radiofrequency Energy in Surgical and Interventional Procedures:

During surgical and interventional procedures, interference may occur between ICDs and electrical cautery or with the application of RF energy. This may lead to the false induction of ICD therapies or could even result in device malfunction, which represents a potential perioperative hazard for the patient. This study analyzed the intraoperative interactions in 45 consecutive ICD patients in reference to different surgical and interventional procedures. A total of 33 surgical operations (general surgery [n = 14], urologic [n = 5], abdominal [n = 10], gynecological [n = 2], thoracic [n = 1], neurosurgical [n = 1]) and 12 interventional therapies (RF catheter ablation [n = 10], endoscopic papillotomy [n = 2]) were performed. The ICD devices were all located in left pectoral position and consisted of 25 single and 20 dual chamber defibrillators. During the procedure, tachyarrhythmia detection (VF 296 +/- 20 ms, VT 376 +/- 49 ms) of the devices was maintained active (monitoring mode), only ICD therapies were inactivated. The indifferent electrode of the electrical cauter/RF generator was placed in standard positions (right/left mid-femoral position [n = 27/8], thoracic spine area [n = 10]). After the procedure, the ICD memory was checked for detections and for changes in the programming. There was no oversensing, reprogramming, or damage of any defibrillator caused by RF energy. Despite the lack of undesired interactions, ICDs should be inactivated preoperatively to assure maximum patient safety. However, should inactivation not be possible, or the achievement uncertain, electromagnetic interference is highly unlikely.

Durability of Repaired Sensing Leads Equivalent to that of New Leads in Implantable Cardioverter Defibrillator Patients with Sensing Abnormalities

Breaks in the insulation portions of implantable cardioverter defibrillator (ICD) leads may cause nonphysiological sensing and subsequent inappropriate ICD therapy, and may also interfere with the sensing and pacing functions of the ICD. Previously, leads with insulation breaks have been replaced with new sensing leads. However, repair of leads, utilizing a commercially available patch kit may reduce the morbidity, hospital stay, and cost of lead replacement. The long-term durability of these repairs has not previously been reported and is the subject of this study. Patients undergoing ICD sensing lead repair or replacement constituted the study population. Patients were followed at 3 month intervals with an endpoint of new lead abnormalities necessitating repeat lead repair or replacement. Twenty-five patients underwent lead repair and 27 individuals underwent lead replacement for either preoperative nonphysiological sensing (n = 25) or intraoperative evidence of insulation break (n = 27). There was no significant difference between the individuals undergoing lead repair or replacement in age (59 +/- 9 vs 60 +/- 12 years), mean left ventricular ejection fraction (40%+/- 18% vs 33%+/- 17%) or age of the lead being repaired or replaced (4.5 +/- 2.0 years vs 5.0 +/- 2.0 years). During follow-up of 44 +/- 23 months, 4 of the repaired leads and 4 of the replaced leads developed new insulation breaks requiring surgical intervention (P = 0.43). In conclusion, in nearly 4 years of follow-up of patients with sensing lead insulation breaks, there was no difference is subsequent lead survival in those with lead repair compared to those with new sensing leads inserted. The strategy of lead repair, when technically feasible, should thus be considered in all patients with sensing abnormalities secondary to insulation breaks.

ICD leads: design and chronic dysfunctions

The treatment of ventricular tachyarrhythmias has changed over the last 10 years. Implantable cardioverter defibrillators (ICDs), once used only as a last resort therapy, have now become the treatment of choice. This change occurred before the first results of randomized studies on ICD therapy in patients with life-threatening ventricular tachyarrhythmias were published by the end of 1997. Technological advances of ICD therapy, in particular the development of transvenous leads, were to a large extent responsible for this change. Modern leads are characterized by their multilumen design that incorporates straight wires and coiled conductors into a single electrode body. Conductors and insulation are sheathed with additional insulation layers. The most frequently used insulating materials are silicone, polyurethane, and fluoropolymers. Lead failures are an important complication of ICD therapy. Fractured conductors, compression, creeping, or insulation defects from abrasion can cause such lead dysfunctions. Chronically implanted leads will inevitably have an increased risk of failure due to defects despite all technological advances. In the light of improving survival figures in patients with ventricular tachyarrhythmias and increasing numbers of ICD implantations, lead failures are becoming a clinical problem of ever increasing importance. Therefore, the question of which lead types necessitate extraction when a certain failure occurs and which leads can be left in place. Despite continuous improvements in lead extraction systems and growing experience in their use, the extraction of any pacemaker or ICD lead is associated with some risk of complications.

Detection and management of an implantable cardioverter defibrillator lead failure: incidence and clinical implications

OBJECTIVES

This study evaluated the long-term reliability of an implantable cardioverter defibrillator (ICD) lead to determine the incidence, clinical presentation, and management of lead failure.

BACKGROUND

Despite recent advances in ICD technology, the long-term reliability of ICD leads remains a significant problem.

METHODS

Concern about long-term reliability of coaxial polyurethane ICD leads caused us to systematically study all patients implanted with Medtronic (Minneapolis, Minnesota) 6936 lead at our institution. We performed follow-up of 74 patients with 76 ICD leads that were implanted from February 28, 1995 to September 8, 1997. Thirty-seven patients underwent routine clinical ICD follow-up testing and ventricular fibrillation induction to determine the status of their ICD lead after a mean follow-up of 68.6 +/- 8.2 months.

RESULTS

The lead survival analysis shows a cumulative failure probability of 37% (confidence interval, 24% to 54%) at 68.6 months. Six patients demonstrated a previously undescribed mode of ICD lead failure: prolonged oversensing immediately after shock therapy. The use of short interval counters to monitor nonphysiologic R-R intervals and the measurement of ring-to-coil impedance detected early lead failures in five patients.

CONCLUSIONS

This analysis shows: 1) problems with ICD leads may not become apparent until late during follow-up and may become a significant late problem, 2) a "signature" mode of lead failure for the 6936 consisting of oversensing of electrical noise following shocks, 3) early detection of lead failure with a short interval counter algorithm or measurement of ring-to-coil impedance may be clinically useful.

Transvenous defibrillation leads: high incidence of failure during long-term follow-up

INTRODUCTION

Patients with implantable cardioverter defibrillators (ICD) critically depend on correct functioning of their system. The aim of this study was to determine the incidence and clinical presentation of transvenous ICD lead failures during long-term follow-up.

METHODS AND RESULTS

The study group consisted of 261 consecutive patients who received Medtronic right ventricular polyurethane transvenous leads (models 6884, 6966, 6936) between 1990 and 1998 as part of an abdominal (n = 70) or pectoral (n = 191) ICD system. During mean follow-up of 4.0 +/- 2.6 years, 31 patients (12%) developed a lead-related sensing failure with oversensing of artifacts. All failures except two were compatible with an insulation defect and occurred late after ICD placement (6.0 +/- 1.8 years after implant). Lead survival decreased from 98% at 4-year follow-up to only 62% at 8-year follow-up. Lead survival was not related to patient age, sex, venous lead implantation route, or device implantation site. In 26 (87%) of 31 patients, a sensing defect resulted in inappropriate detection of ventricular fibrillation and subsequent delivery of 3 +/- 3 (range 1-11) inappropriate shocks in 19 (61%) of 31 patients. Device interrogation showed artifacts classified as nonsustained ventricular tachycardia in 21 patients, 40 +/- 43 days before clinically relevant failure of the system. One patient with a subclavian crush syndrome required resuscitation because of undersensing of true ventricular fibrillation.

CONCLUSION

Transvenous polyurethane ICD leads showed a high rate of lead insulation failure late after implantation with frequent inappropriate shock deliveries. Close follow-up is mandatory in patients with these leads. Automated device control features with patient alert function integrated into new devices may contribute to early detection of lead failure.

Implantable Cardioverter Defibrillator: Current Progress and Management

With greater technologic advances during the past decade, use of the implantable cardioverter defibrillator (ICD) has increased to more than 200,000 implants worldwide to date. Indications for ICD implant have expanded to include both patients who have survived sudden cardiac death (secondary prevention of cardiac arrest) and those who are at high risk for experiencing lethal arrhythmias (primary prevention of cardiac ar rest). Thus, it is likely that physicians will encounter defibrillators in their clinical practice and must be familiar with their indications for implant, basic opera tion, and long-term management of devices. Several prospective clinical trials have recently shown the long- term efficacy of ICD therapy at aborting sudden death in the high-risk patient population. Although still evolving, general guidelines and indications for ICD implant have been put forth and are discussed in this review. From the first defibrillation in humans during surgery in 1947 to the sophisticated dual-chamber pacing and memory functions of the modern device, ICD development has led to ever smaller devices with more complex technol ogy. The implant procedure of current ICDs parallels that used to place pacemakers. However, the anesthe sia team plays a vital role in initial ICD implantation by monitoring cardiopulmonary status during defibrilla tion threshold (DFT) testing. Additionally, long-term management of ICDs often requires repeat DFT testing with anesthesia involvement. Finally, possible electro magnetic (environmental) interactions with the ICD of which physicians should be aware are described in this article.

Defibrillator challenges for the new millennium: the marriage of device and patient-making and maintaining a good match

Although it has become clear that implantable cardioverter defibrillators (ICDs) are effective, important challenges remain for the physician. Due to the limitations of available risk stratification tools, patient selection for primary sudden death prevention remains controversial in many populations. Additionally, the proliferation of device choices has led to challenges in matching the appropriate device to the individual patient: device size is balanced against longevity; the advantages of dual chamber systems is weighed against their increased complexity; physician and patient preferences in device implant site are constrained by site-dependent effects on defibrillation effectiveness and lead failure rates; and special consideration must be given to the patient with a preexisting pacemaker. After ICD placement, determination of appropriate follow-up frequency and methodology to assess device function must be considered. This article will review patient selection, device implant site selection, device-device interactions, single versus dual chamber ICD selection, and follow-up.

ICD hardware failure associated with multiple internal shocks

The delivery of 37 shocks by an ICD within 20 minutes, in response to T wave oversensing during atrial flutter, resulted in several manifestations of undesirable device behavior. The generator reverted to backup mode, and disabled automatic capacitor reformation, therapy delivery, and automatic gain control. Postexplant analysis of the device revealed damage to the high voltage output section of the circuitry consistent with excessive electrical stress. In rare circumstances, multiple internal discharges can result in serious clinical anomalies in ICD behavior, and possibly in an increase in susceptibility to circuitry damage.

Are routine arrhythmia inductions necessary in patients with pectoral implantable cardioverter defibrillators?

INTRODUCTION

The value of ventricular arrhythmia inductions as part of routine implantable cardioverter defibrillator (ICD) follow-up in new-generation pectoral ICDs is unknown.

METHODS AND RESULTS

We performed a retrospective analysis of a prospectively collected database analyzing data from 153 patients with pectoral ICDs who had routine arrhythmia inductions at predismissal, and 3 months and 1 year after implantation. Routine predismissal ventricular fibrillation (VF) induction yielded important findings in 8.8% of patients, all in patients with implantation defibrillation threshold (DFT) > or = 15 J or with concomitant pacemaker systems. At 3 months and 1 year, routine VF induction yielded important findings in 5.9% and 3.8% of tested patients, respectively, all in patients who had high DFT on prior testing. Ventricular tachycardia (VT) induction at predismissal, and 3 months and 1 year after implantation resulted in programming change in 37.4%, 28.1%, and 13.8% of tested patients, almost all in patients with inducible VT on baseline electrophysiologic study and clinical episodes since implantation.

CONCLUSION

Although helpful in identifying potentially important ICD malfunctions, routine arrhythmia inductions during the first year after ICD implantation may not be necessary in all cases. VF inductions have a low yield in patients with previously low DFTs who lack concomitant pacemakers. VT inductions have a low yield in patients without baseline inducible VT and in the absence of clinical events. Definite recommendations regarding patient selection must await larger prospective studies as well as consensus in the medical community about what comprises an acceptable risk justifying avoidance of the costs and inconveniences of routine arrhythmia inductions.

Inappropriate implantable defibrillator discharge caused by a retained pacemaker lead fragment

INTRODUCTION

Inappropriate discharge is still a major issue of implantable cardioverter defibrillator therapy. The diagnostic options of modern devices facilitate classification of the underlying abnormality.

METHODS AND RESULTS

A 65-year-old woman with depressed left ventricular performance received spurious shocks from an ICD, implanted for ventricular tachycardia. A lead fragment of an explanted VVI pacemaker system could be identified as cause of erroneous ventricular fibrillation detection by the ICD. The electrical noise caused by interaction between the lead remnant and the ICD lead was detectable even on the surface ECG.

CONCLUSION

Based on our findings, removal of fragmented lead material should be considered prior to ICD implantation, to avoid potentially adverse and harmful interactions with ICD systems.

Reliability of coated wire defibrillation leads

A higher rate of complications and need for reoperation has been identified with epicardial and endocardial defibrillator systems. Improved reliability may be achieved with alternate designs that use coated wire and coated coil conductors. Six-year reliability in the 98% range is reported for one bipolar design, the Sulzer Intermedics Intervene lead.

Short- and long-term performance of a tripolar down-sized single lead for implantable cardioverter defibrillator treatment: a randomized prospective European multicenter study. European Endotak DSP Investigator Group

A new, thinner (10 Fr) and more flexible, single-pass transvenous endocardial ICD lead, Endotak DSP, was compared with a conventional lead, Endotak C, as a control in a prospective randomized multicenter study in combination with a nonactive can ICD. A total of 123 patients were enrolled, 55 of whom received a down-sized DSP lead. Lead-alone configuration was successfully implanted in 95% of the DSP patients vs 88% in the control group. The mean defibrillation threshold (DFT) was determined by means of a step-down protocol, and was identical in the two groups, 10.5 +/- 4.8 J in the DSP group versus 10.5 +/- 4.8 J in the control group. At implantation, the DSP mean pacing threshold was lower, 0.51 +/- 0.18 V versus 0.62 +/- 0.35 V (p < 0.05) in the control group, and the mean pacing impedance higher, 594 +/- 110 omega vs 523 +/- 135 omega (p < 0.05). During the follow-up period, the statistically significant difference in thresholds disappeared, while the difference in impedance remained. Tachyarrhythmia treatment by shock or antitachycardia pacing (ATP) was delivered in 53% and 41%, respectively, of the patients with a 100% success rate. In the DSP group, all 28 episodes of polymorphic ventricular tachycardia or ventricular fibrillation were converted by the first shock as compared to 57 of 69 episodes (83%) in the control group (p < 0.05). Monomorphic ventricular tachycardias were terminated by ATP alone in 96% versus 94%. Lead related problems were minor and observed in 5% and 7%, respectively. In summary, both leads were safe and efficacious in the detection and treatment of ventricular tachyarrhythmias. There were no differences between the DSP and control groups regarding short- or long-term lead related complications.

Adverse events with transvenous implantable cardioverter-defibrillators: a prospective multicenter study. European 7219 Jewel ICD investigators

BACKGROUND

A newly developed classification system relates adverse events to the surgical procedure or the function of the implantable defibrillator.

METHODS AND RESULTS

Adverse events were monitored during prospective clinical evaluation of the Medtronic model 7219 Jewel ICD and were classified according to the definitions of the ISO 14155 standard for device clinical trials into 3 groups: severe and mild device-related and severe non-device-related adverse events. In addition, events were related to the surgical procedure, treatment with the device, or cardiac function. Seven hundred seventy-eight patients were followed up for an average of 4.0 months after ICD implantation. In total, 356 adverse events were observed in 259 patients. At 1, 3, and 12 months after ICD implantation, 99%, 98%, and 97% of the patients, respectively, survived; 95%, 93%, and 92%, respectively, were free of surgical reintervention; and 79%, 68%, and 51%, respectively, were free of any adverse event. Twenty patients died: 6 deaths were related to the surgical procedure, 12 deaths were considered unrelated to ICD treatment, and 2 patients died of an unknown cause. Of 111 nonlethal severe adverse device effects, 47 required surgical intervention, 19 times for correction of a dislodged lead. Inappropriate delivery of therapy was observed 128 times in 111 patients, and the events were typically resolved by reprogramming or drug adjustment. Nine of these required rehospitalization.

CONCLUSIONS

Approximately 50% of patients experience an adverse event within the first year after ICD implantation. The observed adverse event rate depends on the definitions and the prospective monitoring. The incidence of inappropriate therapy emphasizes the need for improved detection algorithms and for quality-of-life evaluations, especially when considering ICD treatment in high-risk but arrhythmia-free patients.

Electrical proarrhythmia: induction of inappropriate atrial therapies due to far-field R wave oversensing in a new dual chamber defibrillator

This case report describes delivery of atrial therapies during a sinus tachycardia in a new dual chamber implantable cardioverter defibrillator inappropriately caused by far-field oversensing of ventricular beats in the atrial channel. Upon classification of the PR interval pattern, the rate criterion for an atrial tachycardia was fulfilled, and the device initiated high-frequency burst pacing as the first stage of programmed tiered atrial therapies. Atrial fibrillation subsequently was induced by high-frequency burst pacing, and eventually a programmed 10-J shock was delivered for successful termination of atrial fibrillation. The phenomenon of far-field oversensing of ventricular beats could be repeatedly observed during exercise testing and abolished by decreasing the atrial sensitivity.

Case report: inappropriate discharge of an implantable cardioverter-defibrillator caused by the combined count criterion

We describe a rare case of an inappropriate defibrillator discharge during a sinus tachycardia with single fast sensed beats fulfilling the ventricular fibrillation rate criterion, activating the "combined count criterion," although the prevalent sinus tachycardia was inside a ventricular tachycardia rate zone, programmed to monitor only mode. The "combined count criterion" is a safety feature that ensures defibrillation therapy in case of a tachyarrhythmia inside the ventricular tachycardia detection zone, that is temporarily crossing the ventricular fibrillation detection rate. This case reports shows that there is a low but unpredictable risk of device therapy even in a zone programmed to monitor only mode. This phenomenon should be considered when a monitor only zone is installed for revelation of slower tachyarrhythmias.

Impact of implant techniques on complications with current implantable cardioverter-defibrillator systems

Implantable cardioverter-defibrillator (ICD) treatment has been in use since 1980 to prevent sudden cardiac death. The high efficacy of the original epicardial systems to terminate tachyarrhythmias was impaired by a substantial perioperative mortality and morbidity. The more "modern" transvenous ICD systems have shown a similar high efficacy in terminating ventricular tachyarrhythmias, but with a lower mortality and morbidity. As a background for discussing the impact on complications with present transvenous implantation techniques, the literature was reviewed. A large pacemaker series was used for comparison. Lead complications clearly related to design, material, or manufacture were not reviewed. The present review, covering 107 references over 40 years, gives support for the notion that in transvenously implanted ICD patients the incidence of acute and late complications related to implantation technique is now acceptable. The rate of hematomas, symptomatic thromboembolic complications, perforations, and to a certain degree infections could be improved, however. The major risk factors for implantation-related complications are discussed, and suggestions for future improvement are given.