The implantable cardioverter defibrillator

A self-powered intracardiac pacemaker in swine model

Harvesting biomechanical energy from cardiac motion is an attractive power source for implantable bioelectronic devices. Here, we report a battery-free, transcatheter, self-powered intracardiac pacemaker based on the coupled effect of triboelectrification and electrostatic induction for the treatment of arrhythmia in large animal models. We show that the capsule-shaped device (1.75 g, 1.52 cc) can be integrated with a delivery catheter for implanting in the right ventricle of a swine through the intravenous route, which effectively converts cardiac motion energy to electricity and maintains endocardial pacing function during the three-week follow-up period. We measure in vivo open circuit voltage and short circuit current of the self-powered intracardiac pacemaker of about 6.0 V and 0.2 μA, respectively. This approach exhibits up-to-date progress in self-powered medical devices and it may overcome the inherent energy shortcomings of implantable pacemakers and other bioelectronic devices for therapy and sensing.

Nanotechnology in coronary heart disease

Coronary heart disease (CHD) is one of the major causes of death and disability worldwide, especially in low- and middle-income countries and among older populations. Conventional diagnostic and therapeutic approaches have limitations such as low sensitivity, high cost and side effects. Nanotechnology offers promising alternative strategies for the diagnosis and treatment of CHD by exploiting the unique properties of nanomaterials. In this review, we use bibliometric analysis to identify research hotspots in the application of nanotechnology in CHD and provide a comprehensive overview of the current state of the art. Nanomaterials with enhanced imaging and biosensing capabilities can improve the early detection of CHD through advanced contrast agents and high-resolution imaging techniques. Moreover, nanomaterials can facilitate targeted drug delivery, tissue engineering and modulation of inflammation and oxidative stress, thus addressing multiple aspects of CHD pathophysiology. We discuss the application of nanotechnology in CHD diagnosis (imaging and sensors) and treatment (regulation of macrophages, cardiac repair, anti-oxidative stress), and provide insights into future research directions and clinical translation. This review serves as a valuable resource for researchers and clinicians seeking to harness the potential of nanotechnology in the management of CHD. STATEMENT OF SIGNIFICANCE: Coronary heart disease (CHD) is the one of leading cause of death and disability worldwide. Nanotechnology offers new strategies for diagnosing and treating CHD by exploiting the unique properties of nanomaterials. This review uses bibliometric analysis to uncover research trends in the use of nanotechnology for CHD. We discuss the potential of nanomaterials for early CHD detection through advanced imaging and biosensing, targeted drug delivery, tissue engineering, and modulation of inflammation and oxidative stress. We also offer insights into future research directions and potential clinical applications. This work aims to guide researchers and clinicians in leveraging nanotechnology to improve CHD patient outcomes and quality of life.

Polymer Nanocomposites with High Energy Density Utilizing Oriented Nanosheets and High-Dielectric-Constant Nanoparticles

The development of high-energy-density electrostatic capacitors is critical to addressing the growing electricity need. Currently, the widely studied dielectric materials are polymer nanocomposites incorporated with high-dielectric-constant nanoparticles. However, the introduction of high-dielectric-constant nanoparticles can cause local electric field distortion and high leakage current, which limits the improvement in energy density. In this work, on the basis of conventional polymer nanocomposites containing high-dielectric-constant nanoparticles, oriented boron nitride nanosheets (BNNSs) are introduced as an extra filler phase. By changing the volume ratios of barium titanate (BT) and BNNSs, the dielectric property of polymer nanocomposites is adjusted, and thus the capacitive energy storage performance is optimized. Experimental results prove that the oriented BNNSs can suppress the propagation of charge carriers and decrease the conduction loss. Using poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) as the polymer matrix, the P(VDF-HFP)/BNNS/BT nanocomposite has a higher discharged energy density compared with the conventional nanocomposite with the freely dispersed BT nanoparticles.

Evaluation of a Novel Educational Intervention to Improve Conversations About Implantable Cardioverter-Defibrillators Management in Patients with Advanced Heart Failure

Background: Implantable cardioverter-defibrillators (ICDs) reduce the incidence of sudden cardiac death for high-risk patients with heart failure (HF), but shocks from these devices can also cause pain and anxiety at the end of life. Although professional society recommendations encourage proactive discussions about ICD deactivation, clinicians lack training in conducting these conversations, and they occur infrequently. Methods: As part of a six-center randomized controlled trial, we evaluated the educational component of a multicomponent intervention shown to increase conversations about ICD deactivation by clinicians who care for a subset of patients with advanced HF. This consisted of a 90-minute training workshop designed to improve the quality and frequency of conversations about ICD management. To characterize its utility as an isolated intervention, we compared HF clinicians' pre- and postworkshop scores (on a 5-point Likert scale) assessing self-reported confidence and skills in specific practices of advance care planning, ICD deactivation discussions, and empathic communication. Results: Forty intervention-group HF clinicians completed both pre- and postworkshop surveys. Preworkshop scores showed high baseline levels of confidence (4.36, standard deviation [SD] = 0.70) and skill (4.08, SD = 0.72), whereas comparisons of pre- and postworkshop scores showed nonsignificant decreases in confidence (-1.16, p = 0.252) and skill (-0.20, p = 0.843) after the training session. Conclusions: Our findings showed no significant changes in self-assessment ratings immediately after the educational intervention. However, our data did demonstrate that HF clinicians had high baseline self-perceptions of their skills in advance care planning conversations and appear to be well-primed for further professional development to improve communication in the setting of advanced HF.

Improving Communication in Heart Failure Patient Care

BACKGROUND

Although implantable cardioverter-defibrillators (ICDs) reduce sudden death, these patients die of heart failure (HF) or other diseases. To prevent shocks at the end of life, clinicians should discuss deactivating the defibrillation function.

OBJECTIVES

The purpose of this study was to determine if a clinician-centered teaching intervention and automatic reminders increased ICD deactivation discussions and increased device deactivation.

METHODS

In this 6-center, single-blinded, cluster-randomized, controlled trial, primary outcomes were proportion of patients: 1) having ICD deactivation discussions; and 2) having the shocking function deactivated. Secondary outcomes included goals of care conversations and advance directive completion.

RESULTS

A total of 525 subjects were included with advanced HF who had an ICD: 301 intervention and 224 control. At baseline, 52% (n = 272) were not candidates for advanced therapies (i.e., cardiac transplant or mechanical circulatory support). There were no differences in discussions (41 [14%] vs. 26 [12%]) or deactivation (33 [11%] vs. 26 [12%]). In pre-specified subgroup analyses of patients who were not candidates for advanced therapies, the intervention increased deactivation discussions (32 [25%] vs. 16 [11%]; odds ratio: 2.90; p = 0.003). Overall, 99 patients died; there were no differences in conversations or deactivations among decedents.

SECONDARY OUTCOMES

Among all participants, there was an increase in goals of care conversations (47% intervention vs. 38% control; odds ratio: 1.53; p = 0.04). There were no differences in completion of advance directives.

CONCLUSIONS

The intervention increased conversations about ICD deactivation and goals of care. HF clinicians were able to apply new communication techniques based on patients' severity of illness. (An Intervention to Improve Implantable Cardioverter-Defibrillator Deactivation Conversations [WISDOM]; NCT01459744).

Main air pollutants and ventricular arrhythmias in patients with implantable cardioverter-defibrillators: A systematic review and meta-analysis

Objective

Previous studies of ambient air pollutants and ventricular arrhythmias in patients with implantable cardioverter-defibrillator (ICD) have yielded mixed results, and the association between air pollution and ventricular arrhythmias in these patients remains unclear. This study aimed to assess and quantify the association between exposure to major air pollutants [CO, inhalable particles (PM₁₀), SO₂, fine particulate matter (PM_2.5), O₃, and NO₂] and the presence of ventricular arrhythmia in patients with ICD.

Methods

The Medline, PubMed, Web of Science, Global Health Library, Virtual Health Library, Population Information Online (POPLINE), and New York Academy of Medicine Grey Literature Report databases were searched to identify studies analyzing the association between ventricular arrhythmias in patients with ICD and the abovementioned main air pollutants. Pooled estimates were generated using a random-effects model or fixed-effects model, according to the value of heterogeneity. Heterogeneity within studies was assessed using Cochran's Q and I² statistics. Funnel plots, Egger's regression test, and Begg's rank correlation method were used to evaluate publication bias. Sensitivity analyses were also conducted to evaluate the potential sources of heterogeneity.

Results

After a detailed screening of 167 studies, seven separate studies were identified. Ventricular arrhythmias in patients with ICD were found to be positively, but not significantly, associated with CO, PM₁₀, SO₂, PM_2.5, and NO_2, with a pooled estimate [odds ratio (OR) associated with each 10 μg/m³ increase in pollutant concentration, except for CO, which was associated with each 1 mg/m³ increase in concentration] of 1.03 [95% confidence interval (CI): 0.92-1.17, P = 0.59] for CO, 1.01 (95%CI: 0.97-1.05, P = 0.55) for PM₁₀, 1.09 (95%CI: 0.95-1.24, P = 0.22) for SO_2, 1.07 (95%CI: 0.95-1.21, P = 0.25) for PM_2.5, and 1.06 (95%CI: 0.98-1.14, P = 0.16) for NO₂. No increased risk of ventricular arrhythmias in patients with ICD was found to be associated with O₃ (OR = 1.00; 95%CI: 0.98-1.01, P = 0.56).

Conclusions

The results of this study provide little evidence that ambient air pollutants affect the risk of ICD discharges for treating ventricular arrhythmias.

Anaesthetic management of pregnant patients with cardiac implantable electronic devices: case reports and review

Heart disease is a leading cause of maternal mortality and morbidity. Pregnant women with structural, conduction or degenerative cardiac disease who require rhythm control or who are at high risk of sudden cardiac death may carry a cardiac implantable electronic device or may occasionally require the insertion of one during their pregnancy. These women are now encountered more frequently in clinical practice, and it is essential that a multidisciplinary approach, beginning from the early antenatal phase, be adopted in their counselling and management. Contemporary cardiac rhythm control devices are a constantly evolving technology with increasingly sophisticated features; anaesthetists should therefore have an adequate understanding of the principles of their operation and the special considerations for their use, in order to enable their safe management in the peripartum period. Of particular importance is the potential adverse effect of electromagnetic interference, which may cause device malfunction or damage, and the precautions required to reduce this risk. The ultimate goal in the management of this patient subgroup is to minimise the disruption to cardiovascular physiology that may occur near the time of labour and delivery and to control the factors that impact on device integrity and function. We present the ante- and peripartum management of two pregnant women with an implantable cardioverter-defibrillator, followed by a review and update of the anaesthetic management of parturients with cardiac implantable electronic devices.

Fearful Appraisals and Behavioral Responses of a Patient with an Implantable Cardioverter Defibrillator

The implantable cardioverter defibrillator (ICD) is an effective treatment device for potentially malignant arrhythmias, including those leading to sudden cardiac death. However, some patients develop a variety of adjustment problems to the ICD. Clinical behavioral scientists have conceptualized ICD adjustment problems using principles of classical conditioning (i.e., cardiophobia), the learned helplessness paradigm of depression, and cognitive-behavioral models of panic. This case study likens ICD adjustment problems to a cognitive-behavioral model of panic and chest pain illustrating the limits of thesemodels in terms of howType I/Type II threat appraisal by the patient serves as a significant barrier to full symptomresolution. This case study supports the need formodifications in suchmodels and related interventions as they relate to the presence of real comorbid risk factors.

Perceived Benefits of Implantable Cardioverter Defibrillator Implantation among Heart Failure Patients and Its Relation to Quality of Life: A Cross-Sectional Study

Introduction

Patients with heart failure (HF) and implantable cardioverter defibrillators (ICDs) may misunderstand the indication of ICDs due to unsatisfactory information. The goal of this study is to evaluate the patient perspective of ICD indication and its relation to quality of life, as well as to identify probable communication gaps between doctors and ICD receivers.

Methods

A total of 119 patients with HF who were implanted with a single-chamber ICD were evaluated in outpatient clinics. Patients with cardiac resynchronization therapy-defibrillators were not included in the study. In a questionnaire, patients were asked about the indication of the ICD procedure and classified according to the perceived benefits.

Results

This study showed that most of the patients (n = 92, 77.3%) believed that ICD was implanted for improvement of heart dysfunction or for symptom relief. According to the perceived benefit groups, physical function, general health, vitality, and role physical scores were significantly lower in the symptom relief group (p < 0.05).

Conclusion

Patients with HF and ICD mostly believed that the cardioverter defibrillator implanted for improving heart function or symptom relief. Doctors play a significant role when a patient is first referred for ICD because less-informed patients are more prone to misunderstand the procedure’s benefits. Moreover, unfulfilled expectations may lead to loss of confidence in applied therapies and result in poor health outcomes.

Electronic supplementary material

The online version of this article (doi:10.1007/s40119-015-0049-8) contains supplementary material, which is available to authorized users.

Use of Implantable Cardioverter Defibrillators in Heart Failure Patients and Risk of Mortality: A Meta-Analysis

BACKGROUND

The purpose of this study was to evaluate the effect of implantable cardioverter defibrillators (ICD) in heart failure (HF) patients compared to pharmacologic/conventional management.

MATERIAL AND METHODS

We searched PubMed, Embase, and Springer Link Library databases up to February 10th, 2014. Pooled risk ratio (RR) and 95% confidence interval (CI) for the mortality of the patients with HF were collected and calculated in a fixed-effects model or a random-effects model, as appropriate. Summary effect estimates were also stratified by sex and follow-up time. Egger's regression asymmetry tests were utilized for publication bias detection.

RESULTS

A total of 7 separate studies including 15 520 patients (10 801 ICD cases and 4719 controls) with HF were considered in the meta-analysis. The overall estimates showed that ICD could statistically significantly reduce the mortality of male (RR=0.73, 95% CI: 0.66-0.80) and female (RR=0.75, 95% CI: 0.63-0.90) patients. In addition, the further stratification subgroup analysis indicated that ICD presented a significant reduction (male: RR=0.72, 95% CI: 0.64-0.81; female: RR=0.69, 95% CI: 0.56-0.85) of mortality after 2-3 years of ICD therapy. The RR (95% CI) effects of mortality after 4-5 years of ICD therapy for males and females were 0.76 (0.51-1.14) and 0.96 (0.68-1.37), respectively.

CONCLUSIONS

This meta-analysis suggests that ICD could reduce HF patient mortality despite the sex difference.

A study to improve communication between clinicians and patients with advanced heart failure: methods and challenges behind the working to improve discussions about defibrillator management trial

We report the challenges of the Working to Improve Discussions About Defibrillator Management trial, our novel, multicenter trial aimed at improving communication between cardiology clinicians and their patients with advanced heart failure (HF) who have implantable cardioverter defibrillators (ICDs). The study objectives are (1) to increase ICD deactivation conversations, (2) to increase the number of ICDs deactivated, and (3) to improve psychological outcomes in bereaved caregivers. The unit of randomization is the hospital, the intervention is aimed at HF clinicians, and the patient and caregiver are the units of analysis. Three hospitals were randomized to usual care and three to intervention. The intervention consists of an interactive educational session, clinician reminders, and individualized feedback. We enroll patients with advanced HF and their caregivers, and then we regularly survey them to evaluate whether the intervention has improved communication between them and their HF providers. We encountered three implementation barriers. First, there were institutional review board concerns at two sites because of the palliative nature of the study. Second, we had difficulty in creating entry criteria that accurately identified an HF population at high risk of dying. Third, we had to adapt our entry criteria to the changing landscape of ventricular assist devices and cardiac transplant eligibility. Here we present our novel solutions to the difficulties we encountered. Our work has the ability to enhance conduct of future studies focusing on improving care for patients with advanced illness.

Integrated approach for smart implantable cardioverter defibrillator (ICD) device with real time ECG monitoring: use of flexible sensors for localized arrhythmia sensing and stimulation

Arrhythmias are the most common cause of death associated with sudden death and are common in US and worldwide. Cardiac resynchronization therapy (CRT), evolving from pacemakers and development of implantable cardioverter defibrillator (ICD), has been adopted for therapeutic use and demonstrated benefits in patients over the years due to its design and intricate functionality. Recent research has been focused on significant design improvement and efforts are dedicated toward device size reduction, weight and functionality in commercially available ICD's since its invention in the 1960's. Commercially available CRT-D has shown advancement on both clinical and technical side. However, improved focus is required on the device miniaturization, technologically supported and integrated wireless based system for real time heart monitoring electrocardiogram (ECG). In the present report a concise overview for the state-of-the art technology in ICDs and avenues for future development are presented. A unique perspective is also included for ICD device miniaturization and integration of flexible sensing array. Sensor array integration along with its capabilities for identifying localized arrhythmia detection and targeted stimulation for enhancing ICD device capabilities is reviewed.

Development and testing of an intervention to improve outcomes for partners following receipt of an implantable cardioverter defibrillator in the patient

The purpose of this article is to describe 3 foundational studies and how their results were used to formulate, design, and test a novel partner intervention for implementation in the immediate post-ICD (implantable cardioverter defibrillator) period after returning home. Nursing's expanding role into chronic illness management in the creation of evidence-based practice is highlighted. A randomized clinical trial comparing 2 intervention programs is being conducted with patients who receive an ICD for the first time and their intimate partners. Primary outcomes are physical functioning, psychological adjustment, relationship impact, and health care utilization.

Wavelet-based features for characterizing ventricular arrhythmias in optimizing treatment options

Ventricular arrhythmias arise from abnormal electrical activity of the lower chambers (ventricles) of the heart. Ventricular tachycardia (VT) and ventricular fibrillation (VF) are the two major subclasses of ventricular arrhythmias. While VT has treatment options that can be performed in catheterization labs, VF is a lethal cardiac arrhythmia, often when detected the patient receives an implantable defibrillator which restores the normal heart rhythm by the application of electric shocks whenever VF is detected. The classification of these two subclasses are important in making a decision on the therapy performed. As in the case of all real world process the boundary between VT and VF is ill defined which might lead to many of the patients experiencing arrhythmias in the overlap zone (that might be predominately VT) to receive shocks by the an implantable defibrillator. There may also be a small population of patients who could be treated with anti-arrhythmic drugs or catheterization procedure if they can be diagnosed to suffer from predominately VT after objectively analyzing their intracardiac electrogram data obtained from implantable defibrillator. The proposed work attempts to arrive at a quantifiable way to scale the ventricular arrhythmias into VT, VF, and the overlap zone arrhythmias as VT-VF candidates using features extracted from the wavelet analysis of surface electrograms. This might eventually lead to an objective way of analyzing arrhythmias in the overlap zone and computing their degree of affinity towards VT or VF. A database of 24 human ventricular arrhythmia tracings obtained from the MIT-BIH arrhythmia database was analyzed and wavelet-based features that demonstrated discrimination between the VT, VF, and VT-VF groups were extracted. An overall accuracy of 75% in classifying the ventricular arrhythmias into 3 groups was achieved.

Control of action potential duration alternans in canine cardiac ventricular tissue

Cardiac electrical alternans, characterized by a beat-to-beat alternation in action potential waveform, is a naturally occurring phenomenon, which can occur at sufficiently fast pacing rates. Its presence has been putatively linked to the onset of cardiac reentry, which is a precursor to ventricular fibrillation. Previous studies have shown that closed-loop alternans control techniques that apply a succession of externally administered cycle perturbations at a single site provide limited spatially-extended alternans elimination in sufficiently large cardiac substrates. However, detailed experimental investigations into the spatial dynamics of alternans control have been restricted to Purkinje fiber studies. A complete understanding of alternans control in the more clinically relevant ventricular tissue is needed. In this paper, we study the spatial dynamics of alternans and alternans control in arterially perfused canine right ventricular preparations using an optical mapping system capable of high-resolution fluorescence imaging. Specifically, we quantify the spatial efficacy of alternans control along 2.5 cm of tissue, focusing on differences in spatial control between different subregions of tissue. We demonstrate effective control of spatially-extended alternans up to 2.0 cm, with control efficacy attenuating as a function of distance. Our results provide a basis for future investigations into electrode-based control interventions of alternans in cardiac tissue.

Utility of postoperative testing of implantable cardioverter-defibrillators

BACKGROUND

Implantable cardioverter-defibrillators (ICDs) can provide life-saving therapies for ventricular arrhythmias. Arrhythmia induction and defibrillation threshold testing is often performed at implantation and postoperatively during long-term follow-up to ensure proper device function.

METHODS

We sought to evaluate the prevalence and predictors of occult device malfunction at follow-up defibrillation testing in asymptomatic individuals. A cohort of 853 patients underwent 1,578 defibrillation tests during the 13-year study period. Defibrillation efficacy was evaluated primarily by the two-shock (2S) method, with an adequate safety margin ≥ 10 joules (J) less than the maximum energy delivered by the ICD.

RESULTS

A total of 38 testing failures requiring intervention were discovered during testing (2.4% of all tests). There were 11 ICD system failures resulting in failure to defibrillate, six with underdetection of ventricular fibrillation, and 21 clinically significant increases in defibrillation threshold. There was a higher incidence of failure in older ICD systems (1996-2002) compared to newer ICD systems (2003-2009), reaching statistical significance (3.6% vs 1.0%; P < 0.01). There were 178 subjects (20.8%) with a >20-J safety margin on previous testing, detected R waves >7.0 mV, and all system components implanted after 2003 at the time of testing who did not have any testing failures (0% vs 5.6%; P < 0.01).

CONCLUSION

Postoperative defibrillation testing identifies a small number of ICD malfunctions in asymptomatic individuals. ICD testing failure is seen more frequently in older systems and in those with borderline results from prior interrogation or testing. These findings suggest that serial postoperative defibrillation testing is not indicated in asymptomatic patients without suspicion for specific problems.

Methodological limitations of psychosocial interventions in patients with an implantable cardioverter-defibrillator (ICD) A systematic review

BACKGROUND

Despite the potentially life-saving benefits of the implantable cardioverter-defibrillator (ICD), a significant group of patients experiences emotional distress after ICD implantation. Different psychosocial interventions have been employed to improve this condition, but previous reviews have suggested that methodological issues may limit the validity of such interventions.

AIM

To review the methodology of previously published studies of psychosocial interventions in ICD patients, according to CONSORT statement guidelines for non-pharmacological interventions, and provide recommendations for future research.

METHODS

We electronically searched the PubMed, PsycInfo and Cochrane databases. To be included, studies needed to be published in a peer-reviewed journal between 1980 and 2008, to involve a human population aged 18+ years and to have an experimental design.

RESULTS

Twelve studies met the eligibility criteria. Samples were generally small. Interventions were very heterogeneous; most studies used cognitive behavioural therapy (CBT) and exercise programs either as unique interventions or as part of a multi-component program. Overall, studies showed a favourable effect on anxiety (6/9) and depression (4/8). CBT appeared to be the most effective intervention. There was no effect on the number of shocks and arrhythmic events, probably because studies were not powered to detect such an effect. Physical functioning improved in the three studies evaluating this outcome. Lack of information about the indication for ICD implantation (primary vs. secondary prevention), limited or no information regarding use of anti-arrhythmic (9/12) and psychotropic (10/12) treatment, lack of assessments of providers' treatment fidelity (12/12) and patients' adherence to the intervention (11/12) were the most common methodological limitations.

CONCLUSIONS

Overall, this review supports preliminary evidence of a positive effect of psychosocial interventions on anxiety and physical functioning in ICD patients. However, these initial findings must be interpreted cautiously because of important methodological limitations. Future studies should be designed as large RCTs, whose design takes into account the specific challenges associated with the evaluation of behavioural interventions.

Risk of ventricular arrhythmia after implantable defibrillator treatment in anxious type D patients

OBJECTIVES

We sought to examine the combination of adverse psychological factors (anxiety, depression, and distressed or Type D personality) as a predictor of ventricular arrhythmias in patients with implantable cardioverter-defibrillators (ICDs).

BACKGROUND

Little is known about the role of psychological factors and their clustering in the occurrence of life-threatening arrhythmias.

METHODS

In this prospective study, 391 patients with an ICD (81% men, age 62.3 +/- 10.4 years) completed anxiety, depression, and Type D personality scales at the time of implantation. The end point was occurrence of ventricular arrhythmia, defined as appropriate ICD therapies, in the first year after implantation.

RESULTS

Ventricular arrhythmias occurred in 19% (n = 75) of patients. Increased symptoms of depression (p = 0.81) or anxiety (p = 0.31) did not predict arrhythmias. However, anxious patients with a Type D personality had a significantly increased rate of ventricular arrhythmias (21 of 71; 29.6%) as compared with other ICD patients (54 of 320; 16.9%; hazard ratio [HR]: 1.89; 95% confidence interval [CI]: 1.14 to 3.13; p = 0.013). When controlled for the effects of sex, age, ischemic etiology, left ventricular dysfunction, prolonged QRS duration, and medication, anxious Type D patients (HR: 1.72; 95% CI: 1.03 to 2.89; p = 0.039) and secondary prevention patients (HR: 1.91; 95% CI: 1.14 to 3.20; p = 0.014) were at increased risk of ventricular arrhythmias.

CONCLUSIONS

Personality modulated the effect of emotional distress; anxiety predicted a 70% increase in risk of arrhythmia in Type D patients but not in other patients. Anxious Type D patients may be identified and offered additional behavioral support after ICD implantation.

Assessment of a remote monitoring system for implantable cardioverter defibrillators

We conducted a multicentre study in five Italian hospitals to assess the feasibility of a remote monitoring service for the follow-up of implanted cardiac devices. The system was designed to monitor device performance as well as physiological aspects of the patient's condition. Sixty-seven patients (mean age 64 years) affected by chronic heart failure and with a biventricular implantable cardioverter defibrillator for cardiac re-synchronization therapy (CRT-D) were enrolled for a three-month observation period. A total of 267 device recordings were transmitted through the ordinary telephone network, with a success rate of 99%. The telemonitoring service was more efficient than conventional face-to-face follow-up in terms of the time savings: both for physicians (4.7 minutes versus 15 minutes for remote and conventional monitoring) and for patients (6.6 minutes versus 116.3 minutes). In addition, a total of 23 clinical events occurred during the study, but only two cases required a clinic visit, thus reducing inappropriate hospital admissions. Finally, the service was well accepted by all the users.

Air Pollution and Cardiac Arrhythmias in Patients with Implantable Cardioverter Defibrillators

Epidemiological studies have demonstrated associations between short-term increases in outdoor air pollution concentrations and adverse cardiovascular effects, including cardiac mortality and hospitalizations. One possible mechanism behind this association is that air pollution exposure increases the risk of developing a cardiac arrhythmia. To investigate this hypothesis, dates of implantable cardioverter defibrillator (ICD) discharges were abstracted from patient records in patients attending the two ICD clinics in Vancouver, BC, for the years 1997-2000. Daily outdoor air pollutant concentrations and daily meteorological data from the Vancouver region were obtained for the same 4-yr period. Generalized estimating equations were used to assess the association between short-term increases in air pollutant concentrations and ICD discharges while controlling for temporal trends, meteorology, and serial correlation in the data. Air pollution concentrations in the Vancouver region were relatively low from 1997 to 2000, as expected. In the 50 patients who resided within the Vancouver region and who experienced at least 1 ICD discharge during the period of follow-up, no significant associations between increased air pollution concentrations and increased ICD discharges were present. When the patient sample was restricted to the 16 patients who had at least 6 months of follow-up and experienced a rate of at least 2 days with ICD discharges per year, there was a statistically significant association between increased sulfur dioxide (SO(2)) concentration and ICD discharge 2 days after the SO(2) increase. When stratified by season, no associations between increased air pollutant concentrations and increased risk of ICD discharge were observed in the summer, although for several pollutants, concentration increases were associated with a decrease in ICD discharges. In the winter, increased SO(2) concentrations again were seen to be associated with increased risk of ICD discharge, at both 2 and 3 days following increases in SO(2) concentrations. These findings provide no compelling evidence that short-term increases in relatively low concentrations of outdoor air pollutants have an adverse effect on individuals at risk of cardiac arrhythmias. The findings regarding SO(2) are difficult to interpret. They may be chance findings. Alternatively, given the very low concentrations of SO(2) that were present in Vancouver, SO(2) may have been serving as a surrogate measure of other environmental or meteorological factors.

A Case-Crossover Analysis of Particulate Air Pollution and Cardiac Arrhythmia in Patients with Implantable Cardioverter Defibrillators

We investigated the relationship between air pollution and incidence of cardiac arrhythmia in a study of patients with implantable cardioverter defibrillators (ICDs). Thirty-four patients (ages 15-85 yr, 80% male) with ICDs residing in the Vancouver, Canada, area were included in the analyses, representing all patients attending the 2 ICD clinics in the study region who had recorded at least 1 ICD discharge during the 14 February to 31 December 2000 study period. Air pollutant (PM(2.5), PM(10), SO(4)(2-), elemental carbon [EC], organic carbon [OC], O(3), SO(2), NO(2), and CO) concentrations on days for which ICD discharges were observed ("case days") were compared to concentrations on control days in case-crossover analyses. Control days were selected symmetrically, 7 days before and after each case day. ICD discharges occurring within 72 h of 1 another were grouped and considered as 1 discharge event. Temperature, relative humidity, barometric pressure, rainfall, and wind speed were included simultaneously as covariates. Sensitivity analyses examined the effect of grouping ICD discharges, of including meteorological variables, and of excluding discharges that were considered inappropriate by a cardiologist. As in previous studies, mean concentrations and interquartile ranges of air pollutants in Vancouver were low (e.g., PM(2.5) mean = 8.2 microg/m(3)). Although in general there were no statistically significant results, there were trends that might indicate associations between pollutants and ICD discharges. Odds ratios (OR) were consistently higher in summer than in winter (e.g., lag 0 per interquartile range increase in EC: 1.09 [0.86-1.37] vs. 0.61 [0.31-1.18]) and, in general, the highest ORs were observed for same-day effects. The one major exception was the observation of high ORs for ozone in winter (e.g., lag 1: 2.27 [0.67-7.66]). While an OR of 1.55 (0.51-4.70) was observed in summer at lag 0 for PM(10), no indications of positive associations were observed for PM(2.5) or SO(4)(2-). For indicators of local combustion-source pollution, EC, OC, CO, and SO(2), ORs were elevated at all lags (0-3 days) in summer. In summary, this study provides little evidence that specific components of PM affect risk of cardiac arrhythmias, although power limited the ability of the study to detect small effects.

Do abandoned leads pose risk to implantable cardioverter-defibrillator patients?

BACKGROUND

With the increased number of implantable cardioverter-defibrillator (ICD) recipients and the frequent need for device upgrading, lead malfunction is a concern, but the optimal approach to managing nonfunctioning leads is unknown.

OBJECTIVE

The purpose of this study was to determine the rate and characteristics of complications related to abandoned ICD leads.

METHODS

Patients with abandoned leads were identified by retrospective review of the Mayo Clinic ICD database from August 1993 to May 2002. We reviewed the medical records to assess long-term follow-up for venous thromboembolic complications, device sensing malfunction, appropriateness of delivered shocks, defibrillation threshold (DFT) values before and after lead abandonment, and subsequent surgical procedures related to devices or leads.

RESULTS

We identified 78 ICD patients (81% males; mean age 63 +/- 14 years) with 101 abandoned leads (69 in the right ventricle, 31 in the right atrium or superior vena cava, 1 in the coronary sinus). During a mean follow-up of 3.1 +/- 2.0 years, neither sensing malfunction nor venous thromboembolic complications were detected. DFT values were high in 13 patients (17%), but there was no significant increase in mean DFT values before and after lead abandonment in 43 patients for whom both values were available (16.2 +/- 9.2 J before abandonment vs 14.1 +/- 5.5 J after; P = .24). Fourteen patients (18%) required further ICD-related surgery; none of these operations were attributed to abandoned leads. Five-year rates of appropriate and inappropriate shocks were 25.9% and 20.5%, respectively.

CONCLUSION

Abandoning a nonfunctioning lead appears to be safe and does not pose a clinically significant additional risk of future complications.

"That's like an act of suicide" patients' attitudes toward deactivation of implantable defibrillators

OBJECTIVE

To understand potential patient barriers to discussions about implantable cardioverter defibrillator (ICD) deactivation in patients with advanced illness.

DESIGN

Qualitative focus groups.

PARTICIPANTS

Fifteen community-dwelling, ambulatory patients with ICDs assigned to focus groups based on duration of time since implantation and whether they had ever received a shock from their device.

APPROACH

A physician and a social worker used a predetermined discussion guide to moderate the groups, and each session was audiotaped and subsequently transcribed. Transcripts were analyzed using the method of constant comparison.

RESULTS

No participant had ever discussed deactivation with their physician nor knew that deactivation was an option. Patients expressed a great deal of anxiety about receiving shocks from their device. Participants discussed why they needed the device and expressed desire for more information about the device; however, they would not engage in conversations about deactivating the ICD. One patient described deactivation "like an act of suicide" and all patients believed that the device was exclusively beneficial. Patients also expressed a desire to have their physician make the decision about deactivation.

CONCLUSIONS

None of the patients in our study knew that they might need to deactivate their ICD as their health worsens. These community-dwelling outpatients were not willing to discuss the issue of ICD deactivation and their attitudes about deactivation might impede patients from engaging in these conversations. These findings are in contrast to findings in other advance care planning research and may be related to the unique nature of the ICD.

"It's like crossing a bridge" complexities preventing physicians from discussing deactivation of implantable defibrillators at the end of life

OBJECTIVE

To understand potential barriers to physician-initiated discussions about Implantable Cardioverter Defibrillator (ICD) deactivation in patients with advanced illness.

DESIGN

Qualitative one-on-one interviews.

PARTICIPANTS

Four electrophysiologists, 4 cardiologists, and 4 generalists (internists and geriatricians) from 3 states.

APPROACH

Clinicians were interviewed using open-ended questions to elicit their past experiences with discussing deactivating ICDs and to determine what barriers might impede these discussions. Transcripts of these interviews were analyzed using the qualitative method of constant comparison.

RESULTS

Although many physicians believed that conversations about deactivating ICDs should be included in advance care planning discussions, they acknowledged that they rarely did this. Physicians indicated that there was something intrinsic to the nature of these devices that makes it inherently difficult to think of them in the same context as other management decisions at the end of a patient's life. Other explanations physicians gave as to why they did not engage in conversations included: the small internal nature of these devices and hence absence of a physical reminder to discuss the ICD, the absence of an established relationship with the patient, and their own general concerns relating to withdrawing care.

CONCLUSION

Whereas some of the barriers to discussing ICD deactivation are common to all forms of advance care planning, ICDs have unique characteristics that make these conversations more difficult. Future educational interventions will need to be designed to teach physicians how to improve communication with patients about the management of ICDs at the end of life.

An updated review of implantable cardioverter/defibrillators, induced anxiety, and quality of life

During the past 2 years the number of studies examining psychopathology and quality of life after ICD implantation has increased dramatically. Variables assessed have included recipient age, gender, and social support network. How recipients respond to having the device, particularly after experiencing firing, has been evaluated in light of new depression and anxiety disorder diagnoses as well as premorbid personality structure. Now the picture of what is known is, if anything, cloudier than it was 2 years ago, with little definitive and much contradictory data emerging in most of these categories. It still seems clear that in a significant minority of ICD recipients the device negatively affects quality of life, probably more so if it fires. Education about life with the device before receiving it remains paramount. Reports continue to appear of patients developing new-onset diagnosable anxiety disorders such as panic and posttraumatic stress disorder. Until recently the strongest predictors of induced psychopathology were considered to be the frequency and recency of device firing. It now seems that preimplantation psychologic variables such as degree of optimism or pessimism and an anxious personality style may confer an even greater risk than previously thought. Certainly many variables factor into the induction of psychopathology in these patients. Among these factors are age, gender, and perception of control of shocks, as well as the predictability of shocks and psychologic attributions made by the patient regarding the device. Another source of variability is this population's medical heterogeneity. Some patients receive ICDs after near-death experiences; others get them as anticipatory prophylaxis. Some have longstanding and entrenched heart disease; others were apparently healthy before sudden dangerous arrhythmias. Diagnoses as diverse as myocardial infarction in the context of advanced coronary artery disease and dilated cardiomyopathy after acute viral infection may warrant ICD placement. Moreover the course of cardiac disease after ICD placement may vary from relative stability to continuing disease progression and severe functional compromise. Unless these and other pre- and postimplantation differences are taken into account, it is almost impossible to make meaningful comparisons between studies. Ideally, future research would consist either of large-scale, randomized, prospective studies using validated structured-interview tools to supplement a literature dominated by self-report measures, unstructured assessments, and anecdotal reports, or of smaller studies designed to focus on particular diagnostic subsets. As ICDs become the standard of care for potentially life-threatening arrhythmias, the rate of implantations continues to increase. Because negative emotions have been linked to an increased incidence of arrhythmias, and untreated or unrecognized psychiatric illness can interfere with adaptation to an ICD, assessing and managing both pre-existing and induced psychiatric disorders becomes even more critical. Greater research attention should be paid to determining which patients meet criteria for anxiety disorders before and after implantation and what premorbid traits predispose to postimplantation psychopathology. The authors predict that psychiatrists will be involved increasingly in caring for this population, offering insights into treatment options that increase the likelihood of successful ICD acceptance and decrease the psychosocial costs of these devices.

Care of the pacemaker/implantable cardioverter defibrillator patient in the ED

As the population ages and the prevalence of cardiovascular disease increases, patients with pacemakers and implantable cardioverter defibrillators (ICDs) more commonly present to the emergency department. These patients can have complex medical issues related to and independent of their pacemaker/ICD that require careful management by the emergency physician. This article will review the major diagnostic and therapeutic considerations in the emergency care of patients with pacemakers and ICDs.

Implantable cardioverter defibrillator algorithms: status review in terms of computational cost

In recent decades, implantable cardioverter defibrillators (ICDs) have improved substantially, becoming the treatment of choice for patients at high risk of life-threatening arrhythmias. Nevertheless, inappropriate shock therapy for non-ventricular arrhythmias is still a problem. Extending the ICD battery lifetime demands very low power consumption, which is obtained at very low microprocessor clock frequencies. Currently, some high-performance algorithms remain beyond the computational capabilities of ICDs. Future ICDs with higher computing power will permit the implementation of computationally intensive algorithms, enhancing the discrimination performance and preventing inappropriate shock therapies. An ICD algorithm status review is presented from the point of view of signal processing techniques and their computational costs. Several examples of discrimination algorithms with increasing computational cost are analyzed. Whereas some of them are already used in commercial ICDs, other algorithms cannot be implemented yet in current ICDs. A solution based on dynamic adaptation of microprocessor power consumption to meet algorithm computational requirements is proposed. This solution allows implementation of complex discrimination algorithms in ICDs without significantly increasing the power consumption.

Understanding implantable cardioverter defibrillator shocks and storms: medical and psychosocial considerations for research and clinical care

The experience of shock is the distinguishing feature for patients with implantable cardioverter defibrillators (ICDs) and is associated with diminished psychological functioning and quality of life. Multiple shocks and ICD storm are a relatively common event among patients with ICDs (10-20%) and may present specific challenging medical and psychological management for the attending health care providers. This paper examines the medical and psychological aspects of ICD shocks and storms and describes a model of biopsychosocial management for patients following the experience of ICD storm. Successful management of patients post shock includes the use of antiarrhythmic medications and careful attention to the causality of the shocks via stored electrograms. The psychological management includes specific attention to debriefing post-shock feelings and attributions, preventing avoidance behavior, and facilitating positive "return to life" actions. Preliminary research examining formal psychosocial treatment supports a cognitive behavioral strategy to reduce psychological distress and facilitate quality of life. Collectively, these data suggest that interdisciplinary management of patients with multiple ICD shocks or the experience of ICD storm is advised, and routine psychological consultation may be indicated for the patient post ICD storm to reduce the possibility of symptoms of post-traumatic stress.

A knowledge-based method for reducing attenuation artefacts caused by cardiac appliances in myocardial PET/CT

Attenuation artefacts due to implanted cardiac defibrillator leads have previously been shown to adversely impact cardiac PET/CT imaging. In this study, the severity of the problem is characterized, and an image-based method is described which reduces the resulting artefact in PET. Automatic implantable cardioverter defibrillator (AICD) leads cause a moving-metal artefact in the CT sections from which the PET attenuation correction factors (ACFs) are derived. Fluoroscopic cine images were measured to demonstrate that the defibrillator's highly attenuating distal shocking coil moves rhythmically across distances on the order of 1 cm. Rhythmic motion of this magnitude was created in a phantom with a moving defibrillator lead. A CT study of the phantom showed that the artefact contained regions of incorrect, very high CT values and adjacent regions of incorrect, very low CT values. The study also showed that motion made the artefact more severe. A knowledge-based metal artefact reduction method (MAR) is described that reduces the magnitude of the error in the CT images, without use of the corrupted sinograms. The method modifies the corrupted image through a sequence of artefact detection procedures, morphological operations, adjustments of CT values and three-dimensional filtering. The method treats bone the same as metal. The artefact reduction method is shown to run in a few seconds, and is validated by applying it to a series of phantom studies in which reconstructed PET tracer distribution values are wrong by as much as 60% in regions near the CT artefact when MAR is not applied, but the errors are reduced to about 10% of expected values when MAR is applied. MAR changes PET image values by a few per cent in regions not close to the artefact. The changes can be larger in the vicinity of bone. In patient studies, the PET reconstruction without MAR sometimes results in anomalously high values in the infero-septal wall. Clinical performance of MAR is assessed by two physicians' inspection of images generated in 30 patients with and without MAR. Noticeable image differences are judged in 14 of 28 (50%) observations with AICD leads, and significant clinical impact is judged in 2 of 28 (7%) of those observations. A polar map analysis shows significant differences in 10 of 14 (71%) studies with AICD leads, and 0 of 16 (0%) studies without AICD leads. These results show that the MAR method is successful in reducing the magnitude of the metal artefact without incorrectly altering cases without metal artefact. In spite of profound changes to the CT image from the moving metal, the PET ACF in that study was changed by no more than 20%.

Use of an apical suctioning device for placement of a posterior epicardial defibrillator patch: a case report

We report a case of a 43-year-old man with dilated cardiomyopathy and intractable ventricular tachycardias who did not respond to percutaneous implantable cardioverter defibrillator therapy and required implantation of epicardial patches. An apical suctioning device was used to retract the apex of the heart outside the mediastinal domain. The device provided excellent exposure and hemodynamic stability to safely implant the posterior epicardial patch.

The body electric: a review of literature on implantable cardioverter defibrillators

The number of scientific research studies expounding the efficacy and effectiveness of the implantable cardioverter defibrillator (ICD) in the treatment of cardiac arrhythmias and the prevention of sudden cardiac death (SCD) is prolific. The results from clinical trials that have led to the acceptance of implanting the human heart with an ICD are not as convincing as medical science would have health-care consumers believe. There are many other scientific studies that deal with the hazards involved in heart implantation with an ICD. It is argued in this paper that the impact of heart implantation with an ICD is hazardous to a person's being in significant ways. Heart implantation with an ICD is hazardous to physiological wellbeing, to psychosocial wellbeing, and to quality-of-life wellbeing. It is also argued that although humanistic studies are beginning to filter through the maze of scientific studies, many gaps remain in ICD research. Scientific researchers agree that there remains much needed knowledge for cardiac patients, their family members, and for health professionals.

Implantable cardioverter-defibrillators, induced anxiety, and quality of life

Since its approval in 1985, the implantable cardioverter-defibrillator (ICD) has supplanted antiarrhythmic drugs as the standard of care for patients with potentially lethal ventricular arrhythmias. The increased popularity of ICDs stems primarily from their safety and tolerability compared with commonly used medications notorious for adverse drug reactions. As ICD indications have broadened, the number of implantations has increased substantially, and more attention has been directed to sequelae of implantation, particularly after ICD firing. Although scant, studies of quality of life and psychiatric symptoms in patients with ICDs consistently report assorted psychiatric disturbances affecting up to 87% of recipients. Depression and anxiety predominate: up to 38% of patients experience symptoms that meet diagnostic criteria for an anxiety disorder. Psychological theories such as the classic conditioning model, learned helplessness model, and cognitive appraisal model have been invoked to conceptualize these new-onset ICD-induced anxiety disorders. Small trials of psychosocial interventions, including support groups and cognitive behavioral therapy, have had mixed results. Little is known about preexisting anxiety disorders in ICD recipients, particularly which premorbid features predict a worse prognosis, other than suggestions that younger patients and those receiving multiple shocks are at greater risk. Prospective studies of the psychopathology of patients with ICDs, both before and after implantation, are warranted.

Short-Term Efficacy of a Telephone Intervention by Expert Nurses After An Implantable Cardioverter Defibrillator

The ICD is a common therapy for treatment of ventricular arrhythmias and prevention of sudden cardiac death. After ICD therapy, 50% of survivors are known to have significantly elevated anxiety, depression, anger, and fear in getting back to normal physical activities. Despite these problems, few interventions to improve adjustment have been rigorously evaluated within a clinical trial format. This article reports the short-term efficacy of a structured weekly educational telephone intervention (8 weeks) delivered by expert cardiovascular nurses to recipients of an ICD. To test these effects, a two-group (n = 84/group) randomized clinical trial design was used with measures at baseline (hospital discharge), 1 month, and 3 months after ICD therapy. The study sample were first time ICD recipients for secondary prevention of sudden cardiac arrest. Primary outcomes included (1) physical functioning (Patient Concerns Assessment [PCA], Short-Form Health Survey [SF-12], ICD shocks), (2) psychological adjustment (State-Trait Anxiety Inventory [STAI]), Centers for Epidemiologic Studies-Depression (CES-D), (3) knowledge (Sudden Cardiac Arrest [SCA] knowledge assessment), and (4) health care use (emergency room visits, outpatient visits, hospitalizations). The intervention group, as compared to the control group, significantly reduced mean PCA symptoms at 1 month (11.3-8.8 vs 9.7-9.3, respectively, P < 0.02), and reduced state anxiety (36.1-31.9 vs 33.1-33.0, respectively, P < 0.08), and enhanced knowledge (21.8-22.4 vs 21.4-21.7, respectively, P < 0.02) at 3 months. The intervention did not significantly impact short-term health care use. A structured telephone intervention delivered during the first 8 weeks after ICD therapy by expert cardiovascular nurses decreased ICD related physical symptoms and anxiety, and increased SCA knowledge over 3 months.

Sudden cardiac death and channelopathies: a review of implantable defibrillator therapy

This article focuses on implantable cardioverter-defibrillator (ICD) therapy in the child/adolescent who is predisposed to sudden cardiac death because of an underlying channelopathy. As such, the primary channelopathies are reviewed briefly. Next, the history of the ICD device and the technological advancements that have enabled its use in pediatrics are discussed. Finally, the clinical experience with ICDs in the young is summarized and general indications for device therapy in young patients who have a channelopathy are provided.

Increase in QT/QTc dispersion after low energy cardioversion of chronic persistent atrial fibrillation

BACKGROUND

The effects of atrial internal cardioversion on QT interval and QT dispersion (parameters associated with increased risk of ventricular tachyarrhythmias) are unknown. We investigated changes in QT interval, QTc and QT dispersion immediately after shock delivery for internal cardioversion in patients with chronic persistent atrial fibrillation.

METHOD

Twenty-two patients with chronic persistent atrial fibrillation (mean duration, 17+/-23 months) underwent transvenous low-energy internal atrial cardioversion with a step-up protocol of shocks delivered between catheters in the right atrium and coronary sinus. (successful shock, 7.2+/-4.2 J). RR interval, QT interval, QTc interval, QT dispersion, and QTc dispersion were all measured on three consecutive beats (at 75 mm/s on at least 9 of 12 leads) and then averaged both before and after (1) the last unsuccessful shock, and (2) sinus rhythm restoration.

RESULTS

All parameters remained similar in the minute before and after the last unsuccessful shock. At 1 min after the successful shock, abrupt increases in QT dispersion (+43.8% vs. pre-shock; P<0.001 at least significant difference analysis) and QTc dispersion (+30.0%; P<0.05) were observed, followed by a gradual return to pre-shock values at 15 min.

CONCLUSIONS

These findings strongly suggest the likely existence of a brief period of increased electrical vulnerability immediately after restoration of sinus rhythm by internal cardioversion. Particular caution should therefore be applied whenever class III antiarrhythmic drugs are administered immediately after successful internal atrial cardioversion.

Psychological therapies for recipients of implantable cardioverter defibrillators

Implantable Cardioverter Defibrillators (ICDs) are an increasingly common therapy for the treatment of ventricular arrhythmias. Whereas most ICD recipients adjust well to living with the implant, a substantial minority suffer anxiety, depression, and anger that appears to be related to the ICD. A large number of studies have reported on the incidence of psychopathology and common psychosocial problems among patients with ICDs, however very few psychological interventions with this cohort have been reported. In an extensive literature search we identified only a handful of studies that described outcomes of psychological interventions, and most of these were in pilot form. Only one randomized controlled study with a homogenous sample of ICD patients has been reported to date. Given the unique situation of patients with ICDs and the particular vulnerability of those who experience frequent shocks, the evaluation of interventions that may improve psychological adjustment within this group would appear a worthwhile endeavor.