Complications of implantable cardioverter defibrillator therapy: follow-up of 241 patients

Subcutaneous implantable cardioverter-defibrillator implantation in a patient with a left ventricular assist device already in place

A 56-year-old man with ischemic cardiomyopathy, a biventricular implantable cardioverter-defibrillator (ICD), and a left ventricular assist device (LVAD) developed a pocket hematoma and infection after an ICD generator change. The biventricular ICD was extracted, and the patient was given a full course of antibiotics. Because he had no indications for bradycardia pacing or biventricular pacing, he was implanted with a subcutaneous ICD under full anticoagulation. There was no interference in sensing or shock delivery from the ICD. The LVAD readings were unchanged during and after the procedure. The patient had an uneventful postoperative course, and both devices were functioning normally. To our knowledge, this is the first reported case of the implantation of a subcutaneous ICD in the presence of an LVAD. This report illustrates that both devices can be implanted successfully in the same patient. In addition, the subcutaneous ICD minimizes the risk of bloodstream infections, which can be fatal in patients who have life-supporting devices such as an LVAD.

Implantable cardioverter-defibrillators in patients with arrhythmogenic right ventricular cardiomyopathy: the course of electronic parameters, clinical features, and complications during long-term follow-up

PURPOSE

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a progressive cardiomyopathy characterized by myocardial atrophy and fibro-fatty replacement of the right ventricle (RV) and ventricular tachyarrhythmias in young patients. Our aim was to evaluate clinical course and electronic parameters in patients with implantable cardioverter-defibrillator (ICD) and ARVC, during long-term follow-up.

METHODS AND RESULTS

We report on 12 patients with ARVC (mean age 40 ± 13 years) who were treated with ICD implantation in our center. Although several RV sites were tested for proper lead positions, the amplitude of R-wave at implantation was quite low (7.4 ± 3.0 mV). After a mean follow-up of 91 ± 28 months, R-wave amplitude significantly decreased to a mean value of 5.4 ± 2.5 mV (p=0.03). We also found a noticeable, nearly significant increase in pacing threshold (p=0.052) and a moderate increase in defibrillation impedance (p=0.07). Six patients (46 %) experienced at least one appropriate ICD therapy; three patients (23 %) experienced inappropriate ICD shocks secondary to the supraventricular tachycardia, T-wave oversensing, and electromagnetic interference.

CONCLUSIONS

ICD in patients with ARVC has been demonstrated to be feasible and safe. In our case series, we found low R-wave amplitudes at implantation and a significant R-wave decrease during follow-up; a considerable and nearly significant increase in pacing threshold was also observed. These findings may be related to the progressive fibro-fatty replacement of RV myocardium. Multiple sites should be tested in the right ventricle if sensing or pacing values are not optimal, and all the electronic parameters should be carefully monitored throughout the entire follow-up.

Outcome of cardioverter-defibrillator implant in patients with arrhythmogenic right ventricular cardiomyopathy

The aim of the present study was to investigate outcomes of implantable cardioverter-defibrillator (ICD) treatment in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC). We reviewed baseline/follow-up data of 15 consecutive ARVC patients (mean age 55 +/- 15 years) and 30 randomly drawn patients with coronary artery disease (CAD) (mean age 60 +/- 10 years) with matching durations of follow-up (all implanted with ICDs for primary/secondary prevention of sudden death). At implant, appropriate placement of the RV lead was more difficult in ARVC patients. During follow-up (median 41 months), appropriate interventions for any ventricular tachyarrhythmias occurred in 8 (53%) ARVC patients and 17 (57%) CAD patients, but the occurrence of high rate (>240 beats/min) ventricular tachyarrhythmias was higher in ARVC patients. Inappropriate ICD interventions occurred in 5 (33%) ARVC patients and 10 (33%) CAD patients. Lead-related adverse events requiring surgical revision occurred in 7 (47%) ARVC patients as compared with 4 (13%) CAD patients (P = 0.0004). While ICD implantation is highly effective for prevention of sudden death in ARVC, it does carry elevated burdens of long-term lead-related adverse events. These findings underline the need of careful follow-up in ARVC aimed at early recognition of complications that can impair ICD function.

Inappropriate implantable cardioverter-defibrillator discharges unrelated to supraventricular tachyarrhythmias

AIMS

The development of implantable cardioverter-defibrillators (ICDs) with QRS morphology discrimination and dual-chamber sensing capabilities has improved the differentiation of supraventricular from ventricular tachycardias (VTs). Inappropriate ICD discharges may result from extracardiac signals caused by electromagnetic interference (EMI), because of electric fields and leakage currents from domestic or medical electrical devices, damaged sensing leads, and various cardiac and extracardiac signals that mimic VT and/or ventricular fibrillation. The aim of our study was to determine retrospectively the incidence and clinical relevance of these ICD behaviours and offer possible therapeutic solutions.

METHODS AND RESULTS

We have observed inappropriate discharges unrelated to supraventricular arrhythmias in 13 (3.9%) of the 336 patients implanted with ICDs in our centre from 1989 to 2005. Seven patients received inappropriate shocks following exposure to external EMI: improperly grounded electric stove, electrically powered watering system, hydro-massage bath, electrical pruner, electrocautery current during cardiac surgery, transcutaneous electric nerve stimulation. In four patients, spurious discharges were related to internal noise of the ICD system from inappropriate lead connections. In two cases, erroneous antitachycardia therapy was delivered following different body signals oversensing (T-wave oversensing, wide QRS double-counting and myopotentials). In nine patients, non-invasive solutions prevented further inappropriate therapies (avoidance of EMI, malfunctioning atrial lead exclusion, ventricular sensing reprogramming). In four patients, surgical revision of the system was required (lead connections or position revision).

CONCLUSION

In our experience, inappropriate ICD discharges unrelated to supraventricular arrhythmias occurred in about 4% of ICD patients. A careful evaluation of clinical data and telemetric information (lead impedance, sensed R-wave, stored electrograms) is essential in order to understand the nature of inappropriate ICD discharges and to select the most appropriate solution.

Aspergillus infection of implantable cardioverter-defibrillator

The use of pacemakers and implantable cardioverter-defibrillators continues to increase for the management of cardiac dysrhythmias and, more recently, heart failure. Long-term complications associated with their use include infection, lead failure, and spurious shocks. Although the risk of infection with intracardiac devices is well known, the clinical presentation of this complication can be insidious, delayed in onset, and difficult to diagnose. We report a case of Aspergillus fumigatus infection of an implantable cardioverter-defibrillator with right-sided endocarditis in a 55-year-old man. The infection presented as persistent pulmonary infiltrates (due to recurrent septic pulmonary embolism) and anemia more than 2 years after implantation of the device. Clinicians should be aware of the variable manifestations resulting from infection of intracardiac devices.

Implantable cardioverter/defibrillator therapy in arrhythmogenic right ventricular cardiomyopathy: single-center experience of long-term follow-up and complications in 60 patients

BACKGROUND

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a major cause of ventricular tachycardia (VT) and cardiac arrest in young patients. We hypothesized that treatment with implantable cardioverter/defibrillators (ICDs) is safe and improves the long-term prognosis of ARVC patients at high risk of sudden death.

METHODS AND RESULTS

Sixty patients with ARVC (aged 43+/-16 years) were treated with transvenous ICD systems. Despite a higher number of right ventricular sites tested for adequate lead positions (P<0.05), lower R-wave amplitudes (P<0.001) were achieved in ARVC patients compared with other entities. During follow-up of 80+/-43 months (396 patient-years), event-free survival was 49%, 30%, 26%, and 26% for appropriate ICD therapies and 79%, 64%, 59%, and 56% for potentially fatal VT (>240 bpm) after 1, 3, 5, and 7 years, respectively. Multivariate analysis identified extensive right ventricular dysfunction as an independent predictor of appropriate ICD discharge. Fifty-three adverse events occurred in 37 patients during the perioperative (n=10) or follow-up (n=43) period, mainly related to the leads (n=31 in 21 patients). No lead perforation was observed. Freedom from adverse events was 90%, 78%, 56%, and 42% and freedom from lead-related complications was 95%, 85%, 74%, and 63% after 1, 3, 5, and 7 years, respectively.

CONCLUSIONS

These results strongly suggest an improvement in long-term prognosis by ICD therapy in high-risk patients with ARVC. However, meticulous placement and long-term observation of transvenous lead performance with focus on sensing function are required for the prevention and/or early recognition of disease progression and lead-related morbidity during long-term follow-up of ICD therapy in ARVC.

Inappropriate ICD Therapy Due to Proarrhythmic ICD Shocks and Hyperpolarization

A 50-year-old man with an ischemic cardiomyopathy underwent ICD implantation for inducible ventricular fibrillation (VF). Sixteen months later he experienced inappropriate ICD therapy due to atrial fibrillation with a rapid ventricular response. The initial shock resulted in the initiation of VF (proarrhythmia) and the patient received an additional shock converting his rhythm to an idioventricular rhythm with a cycle length of 490 ms (122 beats/min). Due to lead hyperpolarization, the device oversensed ventricular events and the patient subsequently received additional shocks.

Sudden death in patients with implantable cardioverter defibrillators: the importance of post-shock electromechanical dissociation

OBJECTIVES

The purpose of this study was to determine the mechanisms of sudden death (SD) in patients with ventricular tachyarrhythmias (ventricular tachycardia/ventricular fibrillation [VT/VF]) treated with an implantable cardioverter defibrillator (ICD).

BACKGROUND

Despite ICD therapy, some patients with VT/VF still die suddenly. Optimal ICD use requires determination of the mechanisms of these residual SDs.

METHODS

We reviewed 320 patient deaths during trials of Medtronic transvenous ICD systems (Medtronic Inc., Minneapolis, Minnesota). Sudden deaths were further categorized according to mechanism. Post-shock electromechanical dissociation (EMD) describes a scenario where VT/VF was appropriately detected and treated by an ICD shock that restored a physiologic rhythm, but death still occurred immediately by EMD.

RESULTS

A mode of death could be ascribed for 317 patients-90 (28%) were sudden, 156 (49%) were non-sudden cardiac, and 71 (22%) were noncardiac. A mechanism of SD was proposed for 68 patients-20 (29%) had post-shock EMD, 17 (25%) had VT/VF uncorrected by shocks, 11 (16%) had primary electromechanical dissociation, 9 (13%) had incessant VT/VF, 5 (7%) had VT/VF after their ICD was deactivated or removed, and 6 (9%) had single instances of various other terminal events. Only New York Heart Association functional class independently predicted SD by post-shock EMD.

CONCLUSIONS

The most common mechanism of SD in patients with an ICD is VT/VF treated with an appropriate shock followed by EMD. As this mechanism accounted for 29% of the SDs to which a cause could be ascribed, this mechanism of SD warrants further investigation.

Australian implantable cardiac defibrillator recipients: quality-of-life issues

Implantable cardioverter defibrillators (ICDs) have become a well-established therapy for people experiencing potentially lethal dysrhythmias. Australian recipients' quality of life and adjustment to the device over time, device-related complications, shock and associated sensations, and potential sequelae have not been widely explored. This paper reports a longitudinal prospective study of Australian ICD recipients (n = 74) to determine their responses to the device, health-related quality of life over time and shock experiences. A questionnaire designed for the study and the Medical Outcomes Trust Quality of Life Instrument, the SF36, were completed by recipients prior to and at 3 and 12 months post insertion. Results show that quality of life decreased for general health and social function between 3 and 12 months. Nearly half (49%) of the recipients received shocks within 12 months and the majority (92%) of these experienced sequelae that could make driving hazardous. Half of the population (49%) were driving at 3 months and 69% by 12 months, including 67% of those who had been shocked. Twenty-seven percent were hospitalized with device-related complications. Driving, the shock experience and rehospitalization, the shock experience and driving behaviour are significant issues for those with the implanted device. While it is a limitation of the study that partners and carers were not included, these findings will also be of interest to them.

Automatic implantable cardioverter-defibrillators

Ventricular fibrillation, a loss of synchronous electrical activity in the heart which leads to hemodynamic collapse, is a leading cause of death. Because of the devastating personal and societal effects of this phenomenon, the automatic cardioverter-defibrillator has been developed for automatic detection and termination of the arrhythmia and is in widespread clinical use. Advances in circuits, leads, waveforms, and signal processing along with increased knowledge of the mechanisms of fibrillation have led to continuing improvements in this device, extending its use to many patients. A device has also been developed for the automatic or semiautomatic treatment of atrial fibrillation, an arrhythmia less life-threatening than ventricular fibrillation, but still a serious health problem. Continued improvement of these devices and the development of qualitatively new approaches hold great promise for exciting therapeutic advances in this area.

The management of surgical complications of pacemaker and implantable cardioverter-defibrillators

The rate of implantation of pacemakers and implantable cardioverter-defibrillators (ICDs) is ever-increasing. The relative ease of device implantation utilizing a relatively simple, expeditious, percutaneous approach, without the requirement for general anesthesia or long recuperation times, has fueled enthusiasm for implantation. However, the complication risk is ever-present and forms the subject of this pragmatic review, which is limited to the management of only the surgical complications of device implantation. The management of surgical complications related to the implantation of pacemakers and ICDs should include (1) awareness of potential complications, (2) a meticulous approach to the implantation procedure to avoid complications, (3) approach to diagnosis and (4) specific therapy. With a clear understanding of the accepted implant indications and potential complications, and a meticulous approach to the implant and post implant follow up, the incidence of complications can be minimized.

Permanent explantation of implantable cardioverter defibrillators

Although ICD therapy is seen as an irrevocable mode of therapy in most patients, a small number of patients do have their devices permanently explanted. The long-term outcome in these patients has not been described. The purpose of this single center study was to evaluate the long-term outcome of patients whose ICD was explanted and not replaced and to propose clinical variables that can be considered when making the decision to discontinue therapy. Ten of 323 (3.1%) patients in our ICD registry had their devices permanently explanted or turned off between 1986 and December 1998. The devices had been in place for 39 +/- 31 months preexplant. No patient had received appropriate therapy prior to surgery, which was indicated for infection or lead fracture. All patients are alive and well 75 +/- 30 months postexplant with 1 (10%) patient requiring late reimplantation. We reviewed the English language literature describing ICD explanation without replacement. A total of 151 patients were reported in eight studies and were followed for up to 30 months postexplant. Excluding patients with terminal illness or heart transplantation 57.6% survived without reimplantation. In selected patients, after not using an ICD for a long period and when clinical circumstances justify, device therapy may be discontinued with some degree of safety.

Inappropriate shocks diagnosed by stored electrograms of implantable cardioverter defibrillators--two case reports

An implantable cardioverter defibrillator is an important therapeutic option for patients with high risk of life-threatening ventricular arrhythmias. However, their use is also associated with several complications including inappropriate shock. Although the most frequent cause of inappropriate shock is supraventricular tachyarrhythmias, lead fracture can also be associated with inappropriate shock. Diagnosis of lead fracture can be made by chest x-ray radiography, fluoroscopic examination, interrogation of the device, and intracardiac electrograms. In this report, the authors present two cases of inappropriate shock due to lead fractures in the costoclavicular region that could only be diagnosed by the help of stored intracardiac electrograms. Methods for diagnosis of lead fractures and modalities to avoid recurrences are also discussed.

Correlation waveform analysis to discriminate monomorphic ventricular tachycardia from sinus rhythm using stored electrograms from implantable defibrillators

In order to examine whether a template-matching program utilizing correlation waveform analysis (CWA) might be used to discriminate monomorphic ventricular tachycardia (MMVT) from sinus rhythm (SR) in patients with implantable cardioverter defibrillators (ICDs), we studied stored episodes of induced MMVT in 25 patients and compared them to corresponding stored SR electrograms. We calculated mean correlation coefficients for SR beats against an SR template chosen within each sinus episode, induced MMVT beats against an induced MMVT template within each ventricular tachycardia episode, and induced MMVT beats against the original SR template. For each patient, the 99.5% lower confidence limit for the mean correlation coefficient of SR beats versus an SR template (patient-specific method) or the empirical correlation coefficient value 0.9 were selected as threshold values to discriminate induced MMVT from SR. The mean correlation coefficient for induced MMVT beats versus the original SR template for each patient was subtracted from both threshold values. A positive value is defined as accurate discrimination of induced MMVT from SR. Using 0.9 for a threshold cut off, 21 of 25 episodes of induced MMVT were accurately labeled with a sensitivity of 84%. Using the patient-specific method, we were able to correctly distinguish 23 of 25 episodes of induced MMVT from SR with a sensitivity of 92%. There was no statistically significant difference between the patient-specific or empirical methods in detecting MMVT (P 50.4). This is the first demonstration using stored intracardiac electrograms from ICDs that CWA is able to discriminate MMVT from SR with high sensitivity. Such a template-matching system may be used for off-line analysis or real-time rhythm discrimination.

Complications of third-generation implantable cardioverter defibrillator therapy

To determine the incidence of complications of third-generation implantable cardioverter defibrillator (ICD) therapy, 144 patients were prospectively studied who underwent first implant of third-generation devices (i.e., ICD systems with biphasic shocks, ECG storage capability, and nonthoracotomy lead systems). During 21 +/- 15 months of follow-up, 41 (28%) patients had one or more complications. No patient died perioperatively (30 days) and no ICD infection was observed during follow-up. Complications included bleeding or pocket hematoma (hemoglobin drop > 2 g/dL) in 5 (3%) patients, prolonged reversible ischemic neurological deficit in 1 (1%) patient, postoperative deep venous thrombosis of leg in 1 (1%) patient, pneumothorax in 2 (1%) patients, difficulty to defibrillate ventricular fibrillation intraoperatively in 2 (1%) patients, generator malfunction in 1 (1%) patient, arthritis of the shoulder in 3 (2%) patients, and allergic reaction to prophylactic antibiotics in 2 (1%) patients. A total of seven lead related complications were observed in six (4%) patients including endocardial lead migration in four (3%) patients. Twenty-three (16%) patients received inappropriate shocks for supraventricular tachyarrhythmias (n = 13), non-sustained ventricular tachycardia (VT) (n = 7), or myopotential oversensing (n = 3). We conclude that serious complications such as perioperative death or ICD infection are rare in patients with third-generation ICDs. Lead-related problems and inappropriate shocks during follow-up are the most frequent complications of third-generation ICD therapy. Recognition of these complications should promote advances in ICD technology and management strategies to avoid their recurrence.

Radiofrequency catheter ablation of atrioventricular junctional ("AV nodal") reentrant tachycardia in patients with implantable cardioverter defibrillators

Catheter ablation of tachycardias has been undertaken successfully in patients with ICDs without damage to the ICD or lead. Ablation of the slow AV nodal pathway, however, is technically challenging because the lead of the ICD lies close to the ablation site. We report successful ablation of AV junctional reentrant tachycardia (AVJRT) in three patients with ICDs. In all cases, the ablation site was within a few millimeters of the ICD lead. The ablation was successful in all cases and did not cause damage to the ICD or lead. The patients have remained free of recurrence of AVJRT during a mean follow-up of 12 months.

Prospective evaluation of the quality and long-term stability of atrial signals in non-thoracotomy defibrillation electrodes: comparison of four different endocardial electrograms

Documentation of atrial signals in stored endocardial electrograms of modern implantable cardioverter-defibrillators (ICD) is a useful tool to classify the underlying arrhythmia leading to device therapy. Newest generations of ICD provide near- and far-field electrograms derived between various endocardial electrodes. The aim of this prospective study was to assess the quality and long-term stability of atrial signals in different far-field configurations including the active can housing.

METHODS AND RESULTS

A total of 300 real-time endocardial electrogram recordings in 60 consecutive patients with a modern ICD in subpectoral position were analysed at the time of implant, pre-hospital discharge, 1, 3 and 12 months follow-up. Four different configurations were evaluated: right ventricular coil to can housing, can housing to pace/sense ring, right ventricular coil to pace/sense tip, and pace/sense tip to pace/sense ring. The best visibility of p-waves at an ECG-resolution of 0.5 mV/mm was seen in the can to coil configuration (77% of the patients). In the can to pace/sense ring electrogram p-waves could be observed in 58% of the patients. No p-waves were visible to pace/sense tip to pace/sense ring. At a resolution of 1.0 mV/mm p-waves were only visible in 10% of all patients exclusively in the can housing to right ventricular coil configuration. The results were stable (100% of the patients) over a follow-up of one year.

CONCLUSIONS

Endocardial far-field electrograms, derived from the can housing and the right ventricular coil provide a p-wave visibility in 77% of the patients and demonstrate a long-term stability over at least one year, provided that the ECG-resolution is set at 0.5 mV/mm. Since the electrogram resolution of stored electrograms depends on the EGM-range, and the ECG-resolution at an EGM-range of 15 mV would be 1 mV/mm, the EGM-range is recommended to be programmed to 7.5 mV to ensure an ECG-resolution of at least 0.5 mV/mm for stored electrograms.

Patch migration: a serious late complication of thoracotomy lead systems

Thoracotomy patch leads used for implantable cardioverter defibrillators (ICDs) are generally safe and effective. We describe two patients in whom a late complication of patch lead migration occurred years after the original implants, causing a bronchopleural fistula in one and lingular lobe collapse in the other patient. We conclude that patch migration is a late but possible complication of extrapericardial ICD leads, and should be suspected in patients who present with hemoptysis, atypical pneumonia, or lung collapse after the initial ICD surgery.

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.

[Current indications for implantable automatic defibrillators]

Since the first implantation in man in 1980 implantable cardioverter defibrillator technology has greatly improved and the number of devices implanted has increased considerably in recent years. Non-thoracotomy lead systems and biphasic shocks are now the approach of choice, offering nearly a 100% success rate. This paper version reviews the current indications for the implantation of implantable cardioverter defibrillator and is an upgraded of an article previously published by the Arrhythmia's Section of the Spanish Society of Cardiology. Recommendations for qualification of centres implanting defibrillators and follow up are also addressed.

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.

Empirical versus tested antitachycardia pacing in implantable cardioverter defibrillators: a prospective study including 200 patients

BACKGROUND

Implantable cardioverter-defibrillators (ICDs) reduce the risk of sudden cardiac death. The objective of this study was to evaluate whether testing of antitachycardia pacing (ATP) for induced ventricular tachycardias (VTs) at predischarge examination can predict ATP success during follow-up.

METHODS AND RESULTS

The study covers 200 consecutive patients who received ICD implants from June 1991 through December 1995. All underwent electrophysiological testing. In 54 patients (ATP tested, group T), ATP terminated induced VTs successfully. In 146 patients (empirically programmed ATP, group E), only ventricular fibrillation could be induced, including 18 with unsuccessful ATP attempts for induced VTs. Disregarding the results of ATP testing, the same ATP scheme was programmed in all patients: three attempts of autodecremental ramp with 81% of the VT cycle length, with 8 to 10 pulses. During a follow-up of 20.4 +/- 10 months, 95% of 3819 spontaneous VTs were successfully terminated with ATP in 42 patients of group T. In group E, 90% of 1346 spontaneous VTs in 81 patients were terminated with ATP. Acceleration after ATP occurred in 2% in group T versus 5% in group E. The success for all episodes in individual patients was > or =90% in >60% of the ATP tested and empirically programmed patients.

CONCLUSIONS

The results of this 200-patient prospective study comparing tested versus empirical ATP show high success (95% versus 90%) for VT termination, with low rates of acceleration. ATP is safe and very effective and should be programmed "on" in all patients regardless of the predischarge EP inducibility.

Infections with nonthoracotomy implantable cardioverter defibrillators: can these be prevented? Endotak Lead Clinical Investigators

Nonthoracotomy ICDs are believed to be the best therapeutic modality for treatment of life-threatening ventricular arrhythmias. Little is known about the risk of infection with initial implantation of these devices. We studied the incidence, clinical characteristics, and risk factors associated with infections in 1,831 patients with nonthoracotomy ICD from the Endotak-C nonthoracotomy lead registry of Cardiac Pacemakers, Inc. A transvenous lead was implanted in 950 patients (51.9%) and a combination transvenous plus subcutaneous patch was used in 881 patients (48.1%). Nine preselected data variables were studied, and all investigators identified as having patients with infections were personally contacted. Infections occurred in 22 (1.2%) of 1,831 patients receiving this nonthoracotomy ICD system. The mean time to infection was 5.7 +/- 6.5 months (range 1-25 months). Staphylococci were isolated in 58% of patients with reported infection. The presence of a subcutaneous defibrillator patch system was associated with the development of infection. Six of 950 patients (0.63%) with a totally transvenous lead system developed infection versus 16 of 838 (1.9%) patients with a transvenous lead plus subcutaneous patch system configuration (P = 0.015, Chi-square test), with an unadjusted estimated odds ratio of 3.06 (CI 1.19-7.86). The risk of infection encountered with the nonthoracotomy ICD is low, estimated from our data to be 1.2%. Placement of a subcutaneous defibrillator patch appears to be an independent risk factor for development of infection.

Inappropriate discharge of an implantable cardioverter defibrillator during atrial flutter and intermittent ventricular antibradycardia pacing

INTRODUCTION

Inappropriate discharges of an implantable cardioverter defibrillator (ICD) are troublesome to the patient and sometimes a difficult task for the physician trying to identify and treat the cause.

METHODS AND RESULTS

For the first time, we report a mechanism of inappropriate ICD discharges during episodes of atrial flutter with a slow ventricular response and intermittent antibradycardia pacing. The episodes occurred in two patients and were triggered by the unique sensing algorithm of the Ventritex Cadence V-100 in combination with the tripolar CPI Endotak 072 transvenous defibrillation lead, which provides integrated bipolar sensing.

CONCLUSION

Besides treatment of the underlying arrhythmia, reprogramming of the device, an electrode position far away from the atria, and true bipolar sensing will enhance the performance of ICD systems with respect to the episodes described here. In addition, more flexible sensing algorithms may, in the future, prevent this overall rare complication.

The vanishing defibrillator syndrome: incidence, mechanism, and clinical relevance

Intraperitoneal migration of an abdominally implanted cardioverter defibrillator is a complication not yet fully described. In a consecutive series of 195 patients, migration occurred between 1 and 20 months in 5 (8%) of the 63 patients in whom a subrectus abdomini placement of the generator was chosen. It was unrelated to the patients' clinical characteristics or the defibrillator model. Dysuria and inability to interrogate the device were present in every subject, and the diagnosis was confirmed by the characteristic abdominal x-ray appearance and the findings at the time of surgery. Adhesions involving the omentum, and in one case, the small bowels, were present in three patients and seem to be related to the length of intraabdominal permanence of the generator. Because this complication may be due to specific anatomical characteristics of the aponeurosis of the abdominal muscles, it is likely that its incidence will be unchanged by the use of smaller devices. A close follow-up of the generators implanted deep to the rectus fascia is therefore advisable.

Experience with unipolar pectoral defibrillation

With simple, single lead unipolar pectoral defibrillators, ICD technology has reached a level of ease and safety comparable to pacemaker implantation. It will be difficult to further decrease the morbidity associated with ICD implantation; just as it will be difficult to improve upon current device treatment of sudden cardiac death. Even as further incremental improvements in devices and leads will undoubtedly occur, at this point in ICD evolution, it is investigating the expanded use of this therapy as a prevention tool that is likely to have the largest overall impact on cardiac arrest survival.

[Influence of waveform and configuration of electrodes on the defibrillation threshold of implantable cardioverter-defibrillators]

The defibrillation threshold (DFT) is no threshold in the true sense. Between energy levels which defibrillate in all cases and energy levels which never defibrillate, a broad range of energies exists which might or might not defibrillate. Thus, the value of the DFT is dependant on the protocol used for its determination. Usually the DFT presents an energy at which the implantable cardioverter-defibrillator (ICD) will defibrillate successfully at a rate of approximately 75%. To achieve a 100% success rate the energy has to be programmed 15 J above the DFT or twice the DFT.Using DFT measurements the energy needed for internal defibrillation could be gradually reduced in the last years. Major break throughs have been the introduction of the biphasic defibrillation waveform and the use of pectorally implanted ICD shells as defibrillation electrodes. The shortening of the defibrillation impulse by the use of lower capacitances could not improve DFTs but allowed to construct ICDs of smaller volume. Addition of a superior vena cava electrode or a subcutaneous array electrode at the left lateral chest to the standard bipolar electrode system (right ventricle, pectoral ICD can) allowed for tri- and quadripolar lead configurations which reduced DFTs on average only slightly but reduced the standard deviation of DFTs significantly and thus helped to avoid high DFTs. Besides building smaller ICDs, reduction of DFTs and thus programming of lower defibrillation ICD energies allows for improved battery longevities and reduced capacitor charging times and thus a lower incidence of syncopes.

Unipolar pectoral defibrillation systems

Over the past 15 years, the implantation of automatic defibrillations has evolved from an obscure, impractical, and often morbid procedure to nearly a routine therapy. Initial large abdominally implanted generators with multiple epicardial leads have given way to much smaller, pectorally implanted systems utilizing only a single lead. These systems are better accepted by physicians and patients and rival recent-generation pacemakers in their implantation simplicity. Outcomes with single lead defibrillator implantation have been excellent. They are 99% effective at eliminating sudden death in large cohorts of patients, with overall survival of 94.4% at 18 months. Previously significant perioperative complications and mortality associated with epicardial systems have been virtually eliminated. Transvenous single lead systems now provide defibrillation efficacy at a level that makes epicardial leads unnecessary in most patients. Although inappropriate shocks are not a morbid complication, they still occur in approximately 15%-30% of patients. This is an area for improvement in defibrillator therapy, which, though invisible in total mortality statistics, is significant in terms of patient comfort and acceptance. Incremental improvements in pulse generator design and defibrillator lead technology are being made. Perhaps the most interesting new development will be the dual chamber device, incorporating and atrial electrode for sensing, pacing, and perhaps, atrial defibrillation. Such improvements will continue to make device therapy of all arrhythmias more versatile and improve patient comfort both in terms of device size and inappropriate shocks. It is unlikely, however, that further technological advances can further diminish the already small complication rate or improve the already excellent efficacy of current single lead systems. Defibrillator technology has already reached a maturity where technological improvements are less significant than efforts to better define the patient population who will benefit from the therapy.

Undertreatment and overtreatment of patients with infected antiarrhythmic implantable devices

BACKGROUND

Infection of implantable defibrillators or pacemakers is a serious complication, reported with increasing frequency probably because of an increase in the total number of devices implanted due to a change in trends in the treatment of arrhythmias. This review is aimed to provide guidelines on how to deal with these infections and which method is most likely to be successful.

METHODS

This is a review of 38 patients with infected antiarrhythmic implantable devices under three different plans of therapy. There were 17 implantable cardioverter defibrillators and 21 pacemakers. In 27, infection occurred after primary implantation (15 pacers, 12 implantable cardioverter defibrillators), and in 11 after replacement (six pacers, five implantable cardioverter defibrillators). Three therapeutic plans were identified. Group I (n = 12) received intravenous antibiotics without removal of the antiarrhythmic implantable device, but with relocation to a different area or plane, and with or without the use of a topical irrigating-suction system. Group II (n = 19) had complete removal of the system, 2 weeks of intravenous antibiotics, and implantation of a new unit followed by 10 more days of antibiotics. Group III (n = 7) underwent complete removal, 6 weeks of antibiotics, implantation of a new unit, and another 6 or more weeks of antibiotic therapy.

RESULTS

Failure occurred in 100% of cases in group I. Groups II and III had complete clearing of infection and successful reimplantation of new systems with no recurring infections. Follow-up was 8 months to 5 years. Two deaths occurred, both in group I. Hospitalization for groups I and III was 104 days and 65 days, respectively, versus 22 days for group II. No deaths occurred in group II or III.

CONCLUSIONS

With an infected antiarrhythmic implantable device, immediate removal of the entire unit is recommended, followed by 2 weeks of intravenous antibiotics, implantation of a new system, and 10 more days of postoperative antibiotics. This regimen is sufficient to cure the problem. No attempts should be made to save an infected system from removal because it endangers the patient's life, prolongs hospitalization, increases costs, and most likely will fail.

Radiofrequency catheter ablation of atrial flutter that elicits inappropriate implantable cardioverter defibrillator discharge

The case of a patient with recurrent VT and an ICD is reported. After appropriate device discharges, the patient experienced 40 episodes of inappropriate shock therapy due to atrial arrhythmias confirmed as type I atrial flutter. Since programmed stimulation could reliably initiate atrial flutter, catheter ablation was performed. During delivery of RF current, atrial flutter terminated and was no longer inducible. The patient had no further inappropriate device discharges during 12 months of follow-up. In patients with ICDs suffering from recurrences of atrial flutter leading to inappropriate shock therapy, RF catheter ablation is an effective and curative approach.

Erosion of internal cardioverter defibrillator pocket and migration of pulse generator into the peritoneal cavity

ICD therapy for life-threatening arrhythmias is well established. As more patients are treated, the incidence of recognized and new complications may increase. We report ICD pocket erosion and migration of the pulse generator into the peritoneal cavity in two patients.

Hospital readmission in patients treated with tiered-therapy implantable defibrillators

BACKGROUND

We wished to determine the incidence, reasons, costs, and predictors of cardiac-related hospital readmission in patients with tiered-therapy implantable defibrillators. Hospital readmission in patients with defibrillators reduces their quality of life and increases the cost associated with such therapy.

METHODS AND RESULTS

We retrospectively studied 65 consecutive local patients (median age, 67 years; median ejection fraction, 0.34) who underwent tiered-therapy defibrillator implantation at this institution. Patients were followed for a median of 19 months (interquartile range, 10 to 27 months). The cause, duration, costs, and predictors of cardiac-related rehospitalizations were analyzed. There were 76 cardiac admissions for 34 patients. The rate of cardiac-related hospital readmission was 0.72 per patient-year of follow-up. Arrhythmia-related admissions accounted for 43 of such admissions in 24 patients. Actuarial freedom from cardiac-related admissions was 0.57 and 0.40 at 1 and 2 years, respectively. The median length of stay for hospital readmissions was 5 days (interquartile range, 3 to 8 days). The median cost per admission was $5842 (interquartile range, $3549 to $12 170). The time to first readmission and the total rehospitalization time per year of follow-up were associated with a poor preimplant New York Heart Association functional class. Readmission for cardiac arrhythmias was not predicted by clinical parameters.

CONCLUSIONS

Rehospitalization for cardiac reasons is common in patients receiving implantable defibrillators and is responsible for substantial resource consumption. The need for readmission for arrhythmia-related reasons cannot be predicted by clinical parameters at the time of device implantation.

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.

First experience with a new nonthoracotomy defibrillation lead system

The clinical efficacy and safety of a new nonthoracotomy defibrillation lead system (TVL lead system, Ventritex, inc., Sunnyvale, Calif.) was studied in patients with ventricular tachycardia or fibrillation. Implantation of the TVL lead system and a Cadence pulse generator (Ventritex, Inc.) was attempted in 27 patients. A subcutaneous patch lead was added if required to achieve adequate defibrillation energy. Patients were monitored for an average of 6 +/- 4 months (range 1 week to 14 months). Implantation was successful in 26 patients (96%). Twenty-three of those patients (88%) were implanted in a lead-alone configuration; the remaining three (12%) required a subcutaneous patch lead. The mean defibrillation threshold was 401 +/- 120 V (12 +/- 7 J) at implantation, 467 +/- 134 V (15 +/- 8 J) at predischarge testing, and 452 +/- 151 V (14 +/- 9 J) at 4-month follow-up. The mean defibrillation threshold at 4 months was not significantly different from that at implant. No deaths, sensing anomalies, infections, lead fractures, or lead dislodgments occurred. One patient required addition of a subcutaneous patch 4 months after device implantation because of an elevated defibrillation threshold. Eight patients (31%) experienced 545 spontaneous arrhythmic episodes, and all episodes were successfully terminated by the device. In conclusion, the TVL lead system combined with Cadence tiered-therapy defibrillator has a high success rate and low complication rate, and it can be recommended for treatment of patients with life-threatening ventricular tachyarrhythmias.

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 long-term 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 25 +/- 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%), dislodgement of the right ventricular lead in 2 patients (2.5%), dislodgement 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, dislodgements, 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 lead 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.

Defibrillator patch electrode constriction: an underrecognized entity

Pericardial constriction associated with the placement of intrapericardial defibrillator patches is a rare occurrence that is reported only one tenth as often in defibrillator patients as in patients undergoing other types of cardiac operations. Although this discrepancy may be attributable to a lower incidence of constriction with the defibrillator patch electrode procedure, it may also indicate a failure to recognize that progressive right heart failure and signs of low cardiac output that could be due to pericardial constriction and not progressive systolic dysfunction. Because surgical removal of the patches and decortication of the epicardial surface is the only effective therapy, it is important to recognize this uncommon, but profoundly debilitating entity.

Postoperative lead-related complications in patients with nonthoracotomy defibrillation lead systems

OBJECTIVES

This study sought to document postoperative complications attributable to nonthoracotomy defibrillation lead systems in a large cohort.

BACKGROUND

The incidence of postoperative complications specifically associated with nonthoracotomy defibrillation lead systems is unknown.

METHODS

Postoperative lead-related complications were evaluated in 170 patients with a nonthoracotomy defibrillation lead system who were followed up for a mean (+/- SD) of 17 +/- 12 months. Each system incorporated one or more intravascular leads. In 117 patients (69%), the system incorporated a subcutaneous defibrillation patch. All implantations were performed in an operating room by cardiothoracic surgeons. Defibrillation thresholds were measured at implantation, before hospital discharge (mean 3 +/- 2 days) and at 4 to 18 weeks after implantation. Patients were evaluated every 2 to 3 months after implantation or as indicated by clinical exigency.

RESULTS

Twenty-seven patients (15.9%) were diagnosed with a lead-related complication that either extended the initial hospital period or led to a second hospital admission. Complications included endocardial lead or subcutaneous defibrillation patch dislodgment in eight patients (4.7%), which was diagnosed between 2 and 345 days after implantation; endocardial or subcutaneous patch lead fracture in six (3.5%), which was diagnosed between 53 and 600 days after implantation; subcutaneous patch mesh fracture in one, which was diagnosed at 150 days after implantation; subclavian vein thrombosis in three (1.8%), which was diagnosed at 2 to 50 days after implantation; and unacceptably elevated defibrillation threshold (within 5 J of maximal device output) in nine (5.3%), which was documented at one of the two postimplantation evaluations in eight patients or at the time of failure to terminate a spontaneous ventricular tachycardia in one. Seventeen of the 27 patients required reoperation for correction of their complication. In addition, system infection requiring complete explantation occurred in seven other patients (4.1%) at an interval from implantation ranging from 14 to 120 days.

CONCLUSIONS

Postoperative complications related to a nonthoracotomy defibrillation lead system were common and frequently required reoperation for correction. The rate of system explantation due to infection was also significant. Postoperative defibrillation testing and vigilant outpatient follow-up evaluation are necessary to ensure normal lead function.

Mechanical complications after implantation of multiple-lead nonthoracotomy defibrillator systems: implications for management and future system design

Nonthoracotomy lead system (NTL) implantable cardioverter defibrillators (ICDs) provide excellent protection against sudden death from ventricular tachyarrhythmias. However, these devices have unique mechanical complications and management issues. We reviewed the major complications occurring in 159 patients who underwent attempted implantation of a multilead NTL system. Successful implantation was obtained in 98% of patients. Two-year, all-cause actuarial survival on an intention-to-treat basis was 94%. Major complications occurred in 28 (17.6%) patients over a follow-up period of 21 +/- 10 months. Complications included 11 (6.9%) lead dislodgements, 10 (5.7%) lead fractures in 9 patients, 2 (1.3%) pocket infections, 1 frozen shoulder, 1 right ventricular perforation, 1 pneumothorax, 1 bleed requiring transfusion, 1 thromboembolism, and 1 "twiddle"-induced torsion of leads. Most of the lead dislodgements and fractures were identified by routine x-ray surveillance. Single-lead systems may significantly reduce complication rates in the future and maintain excellent survival rates.