Psychological intolerance to implantable cardioverter defibrillator

Background: Implantable cardioverter defibrillators (ICD) are mobile implantable cardiac devices for immediate treatment of live threatening ventricular arrhythmias. However, these devices can affect patients, physiologically, psychologically and have effects on electrical devices. Case report: The case of a 61-year-old patient is reported. The patient came for regular 3-months visits with his ICD and complained about electromagnetic interference with all household electrical appliances, especially refrigerator and digital television set-top box. He described several phantom shocks when he came close to the electrical appliances. He noted the exact times and symptoms of the episodes but the device memory did not record anything. Conclusion: This case demonstrates the rare occurrence of psychological intolerance to implanted ICD shortly after implant. The device was programmed for higher sensitivity. The patient was calmed and reassured about the reprogramming.     

Termination of Ventricular Tachycardia with Antitachycardia Pacing after Ineffective Shock Therapy in an ICD Recipient with Hypertrophic Cardiomyopathy

Implantable Cardioverter Defibrillator (ICD) implantation is the only established therapy for primary or secondary prevention of sudden cardiac death in patients with Hypertrophic Cardiomyopathy (HCM). Ineffectiveness of shock therapy for the termination of potentially fatal ventricular arrhythmias in ICD recipients is rare in the presence of appropriate arrhythmia detection by the device. We report the case of a 48-year-old woman with HCM and a single chamber ICD, who received five inefficient high-energy (35 Joules) shocks for the termination of an appropriately detected episode of Ventricular Tachycardia (VT). The episode was safely terminated with a subsequent application of Antitachycardia Pacing (ATP) by the device. At the following ICD control, an acceptable defibrillation threshold was detected.     

The future of electrical defibrillators for the heart]

The aim of electric defibrillation of the heart is to salvage a greater percentage of victims of cardiac arrest in the future. An initial decisive pathway towards this goal is to get a defibrillator to the victim as quickly as possible and apply an electric shock. This has now been implemented on a large scale--by means of the widespread propagation of (semi-)automatic external defibrillators (AED) and their PAD (Public Access Defibrillator) variant for use by laypersons. This is an initial necessary prerequisite which, however, is not sufficient to have a real impact on saving lives. For experience has shown that, despite the early use of AEDs, an appreciable proportion of the victims cannot be saved. The intention is to improve this situation by increasing the efficacy and reducing the harmful downside of the defibrillation waveforms applied. The solution is optimally dimensioned biphasic waveforms with high efficacy at low energy levels. In this connection, it is shown that the efficacy of high-energy defibrillation shocks is exceeded by their injurious effects, thus thwarting life-saving defibrillation. Examples of new waveforms of particularly high efficacy are presented. It is shown how such impulses should be physiologically dimensioned, and clinical results of cardioversion (atrial defibrillation) and initial out-of-hospital results of emergency defibrillation are discussed. In addition, new approaches for future waveforms enabling pulsed pulse-pause-modulated biphasic shocks are described. In this way, waveforms with a physiologically optimal effect on the heart can be produced which were previously impossible with portable defibrillators. Waveforms that have already been tested or are still in the research stage, justify hopes that improved survival of cardiac arrest victims may be expected. These new waveforms may also be of benefit in other types of defibrillators (e.g. cardioversion or implanted defibrillators).     

Povidone-iodine Irrigation - A Possible Alternative To Lead Extraction

Pocket infection and erosion remain the commonest (class 1) indication for pacemaker (PM) or implantable cardiac defibrillator (ICD) lead extraction. However, tranvenous lead extraction is not without significant risk of serious complications, particularly in patients with chronically implanted leads or ICD leads specifically. The paucity of cardiologists adequately experienced to undertake this high-risk procedure also means that its availability is limited to relatively few specialist institutions, yet more conservative 'lead-preserving' treatment options have not been well-reported. We describe the first reported case of a chronically eroded and infected ICD generator, managed conservatively with 5-days of povidone-iodine closed irrigation, followed by re-implantation of a new ICD on the contralateral side. With satisfactory long-term follow-up, this successfully averted the need for lead extraction in our elderly patient. We advocate the need for formal prospective evaluation of conservative therapeutic strategies of PM and ICD pocket infections. Although not gold standard, it provides an important therapeutic alternative in resource-limited areas.     

First experience with the wearable cardioverter defibrillator in the Netherlands

The implantable cardioverter defibrillator (ICD) has significantly improved survival in patients with an increased risk of sudden cardiac death (SCD). The wearable cardioverter defibrillator (WCD) is an alternative to the ICD in patients with a transient ICD indication or those in whom an ICD temporarily cannot be implanted. We describe here the technical details of the WCD and report three patients who were treated with a WCD in an outpatient setting. The WCD allowed the cardiac condition of two patients to improve to such an extent that permanent ICD implantation was deemed unnecessary. This new form of therapy may result in significant cost reduction, avoidance of unnecessary ICD implantation, and increased patient satisfaction.     

Influence of time between last myocardial infarction and prophylactic implantable defibrillator implant on device detections and therapies. Routine Practice data from the SEARCH MI registry

ABSTRACT: BACKGROUND: A multicenter European Registry, SEARCH-MI, was instituted in the year 2002 in order to asses patients' outcomes and ICD interventions in patients with a previous MI and depressed LV function, treated with an ICD according to MADIT II results. In this analysis, we evaluate the influence of the time elapsed between last myocardial infarction (MI) and prophylactic cardioverter defibrillator (ICD) implant on device activations. METHODS: 643 patients with left ventricular dysfunction (mean LVEF 26 +/- 5%) and NYHA class I-III were prospectively followed for 1.8 +/- 1.2 years in a multicenter registry. The population was divided into 3 groups according to the time between last MI and ICD implant: [1] from 40 days to less than 1.5 years; [2] from 1.5 to less than 7 years and [3] at least 7 years. RESULTS: The cumulative incidence of ventricular tachyarrhymias and appropriate device therapy (ATP or shock) were higher in patients implanted longer time from last MI (Gray's Test p = 0.002 and p = 0.013 respectively). No significant differences were seen in all cause mortality (Gray's Test p = 0.618) or sudden cardiac death across the MI stratification groups (Gray's Test p = 0.663). CONCLUSIONS: Patients implanted with an ICD longer after the MI have a higher chance of presenting ventricular tachyarrhythmias and appropriate ICD therapy, while no differences were seen in overall mortality. These observations may be important for improving patient targeting in sudden death prevention.     

Defibrillation testing of the implantable cardioverter defibrillator: when, how, and by whom?

The implantable cardioverter-defibrillator (ICD) has become an integral part of treatment for a variety of patients with symptomatic, or at risk for, ventricular tachyarrhythmias. The ICD's effectiveness is attributed to its ability to promptly detect and terminate ventricular tachycardia (VT) and fibrillation (VF). The clinical trials that established the positive role of ICD therapy were based on patients who underwent some form of defibrillation testing at the time of implantation. Therefore, since its advent, intraoperative defibrillation testing of the ICD to assure reliable detection and termination of VT/VF has been a standard practice. But because of advances in defibrillator and lead technology, which now facilitates successful device implantation (i.e., low defibrillation energy requirement to allow for an adequate programmed safety margin) in the majority of patients, the necessity of defibrillation testing has been called into attention. Despite substantial progress, it is not altogether clear whether a wholesale abandonment of intraoperative ICD testing is appropriate at this point. We review pertinent data regarding pros and cons of ICD testing and offer a suggestion as to when, how, and who should test ICDs.     

Cardiac Resuscitation—The Present Status of Defibrillation and Stimulation Techniques

Recent advances in electrical treatment and control of the heart are reviewed. The methods which have evolved for AC and DC countershock defibrillation and arrhythmia correction are outlined, and the parameters defined for determination of the efficacy of treatment.The principal types of cardiac stimulation are described and evaluated in terms of their electrical energy requirements. Externally controlled and implanted stimulators are compared and causes of failure stated.Current developments, reported at a recent Conference on Pacemakers, are included, with a summary of discussions by leading investigators in the field.Studies conducted by the National Research Council (Canada) medical electronics laboratory are also discussed.     

Morphological detection algorithms for the automatic implantable cardioverter/defibrillator (AICD).

To prevent sudden cardiac death of patients who are at risk from long standing tachyarrhythmia the implantable cardioverter defibrillator (ICD) is the first choice therapy. ICDs use a range of electrostimuli up to defibrillation, which is a non synchronous high energy shock, whereas cardioversion is synchronous with the ECG. In order to know when and how to react, a detection algorithm, which analyses an intracardial electrocardiogram (ECG) and classifies the heart rhythm, is implemented in every ICD. All detection algorithms use the heart rate to classify the different heart rhythms roughly. If a tachycardia is detected, it is important to discriminate between a ventricular tachycardia, which is life threatening and a supraventricular tachycardia, which is much less threatening. To be able to make this distinction the detection algorithms analyse the behaviour of the heart cycle intervals, the ECG-morphology or in addition to the ventricular ECG, an atrial ECG. In this paper morphological algorithms will be evaluated and newly developed algorithms will be presented. Recent algorithms use the mathematical wavelet theory. The evaluation shows that these get better results than all but one of the simpler classical morphological algorithms. A new wavelet based algorithm, developed by the authors, exhibits the best detection results.     

The role of biphasic shocks for transthoracic cardioversion of atrial fibrillation

The modern generation of transthoracic defibrillators now employ impedance compensated biphasic waveforms. These new devices are superior to those with monophasic waveforms and practice is currently switching to biphasic defibrillators for the treatment of both ventricular and atrial fibrillation. However, there is no universal guideline for the use of biphasic defibrillators in direct current cardioversion of atrial fibrillation. This article reviews the use of biphasic defibrillation waveforms for transthoracic cardioversion of atrial fibrillation.     

Low efficacy of cardioversion of persistent atrial fibrillation with the implantable cardioverter-defibrillator

Aims

Atrial fibrillation (AF) and heart failure are conditions that often coexist. Consequently, many patients with an implantable cardioverter-defibrillator (ICD) present with AF. We evaluated the effectiveness of internal cardioversion of AF in patients with an ICD.

Methods

Retrospectively, we included 27 consecutive ICD patients with persistent AF who underwent internal cardioversion using the ICD. When ICD cardioversion failed, external cardioversion was performed.

Results

Patients were predominantly male (89 %) with a mean (SD) age of 65 ± 9 years and left ventricular ejection fraction of 36 ± 17 %. Only nine (33 %) patients had successful internal cardioversion after one, two or three shocks. The remaining 18 patients underwent external cardioversion after they failed internal cardioversion, which resulted in sinus rhythm in all. A smaller left atrial volume (99 ± 36 ml vs. 146 ± 44 ml; p = 0.019), a longer right atrial cycle length (227 (186–255) vs. 169 (152–183) ms, p = 0.030), a shorter total AF history (2 (0–17) months vs. 40 (5–75) months, p = 0.025) and dual-coil ICD shock (75 % vs. 26 %, p = 0.093) were associated with successful ICD cardioversion.

Conclusion

Internal cardioversion of AF in ICD patients has a low success rate but may be attempted in those with small atria, a long right atrial fibrillatory cycle length and a short total AF history, especially when a dual-coil ICD is present. Otherwise, it seems reasonable to prefer external over internal cardioversion when it comes to termination of persistent AF.     

Atrial fibrillation: an unusual cause

A 28-year-old male presenting with atrial fibrillation (AF) underwent successful electrical cardioversion to restore sinus rhythm. He had no prior history of AF or other cardiac disease. However, transthoracic echocardiography (TTE), performed to exclude structural abnormalities as a cause of AF, demonstrated a large mass in the left atrium (LA). For further analysis the patient was referred to our centre, and echocardiography, multislice detector computed tomography (MDCT) and cardiovascular magnetic resonance imaging (CMR) were performed for further noninvasive diagnostic work-up.     

Electrical storm: Incidence, Prognosis and Therapy

Implantable defibrillators are lifesavers and have improved mortality rates in patients at risk of sudden death, both in primary and secondary prevention. However, they are unable to modify the myocardial substrate, which remains susceptible to life-threatening ventricular arrhythmias. Electrical storm is a clinical entity characterized the recurrence of hemodynamically unstable ventricular tachycardia and/or ventricular fibrillation, twice or more in 24 hours, requiring electrical cardioversion or defibrillation. With the arrival of the implantable cardioverter-defibrillator, this definition was broadened, and electrical storm is now defined as the occurrence of three or more distinct episodes of ventricular tachycardia or ventricular fibrillation in 24 hours, requiring the intervention of the defibrillator (anti-tachycardia pacing or shock). Clinical presentation can be very dramatic, with multiple defibrillator shocks and hemodynamic instability. Managing its acute presentation is a challenge, and mortality is high both in the acute phase and in the long term. In large clinical trials involving patients implanted with a defibrillator both for primary and secondary prevention, electrical storm appears to be a harbinger of cardiac death, with notably high mortality soon after the event. In most cases, the storm can be interrupted by medical therapy, though transcatheter radiofrequency ablation of ventricular arrhythmias may be an effective treatment for refractory cases.This narrative literature review outlines the main clinical characteristics of electrical storm and emphasises critical points in approaching and managing this peculiar clinical entity. Finally focus is given to studies that consider transcatheter ablation therapy in cases refractory to medical treatment.     

Rate and predictors of electrical failure in non-recalled defibrillator leads

BackgroundImplantable cardioverter defibrillator (ICD) leads are considered as the ‘weakest link’ in defibrillator systems due to FDA recalls and advisories involving popular lead models from major manufacturers. The rate of electrical failure of ICD leads not implicated in a recall is however not well determined.MethodsMedical records of patients implanted with ICDs at hospitals of the University of Pittsburgh Medical Center between 2002 and 2014 were analyzed. Leads were classified as having electrically failed if removed or replaced for reasons other than infection or heart transplantation. Patients were followed to endpoint of death or electrical lead failure.Results2410 consecutive ICD recipients (mean age 66 ± 13 years, women 22%, single/dual/biventricular-ICD 20%/44%/36%) were included. During a mean follow-up of 3.9 ± 3.3 years, 1272 patients (53%) died, 55 patients (2.3%) had ICD lead electrical failure, and 1052 (44%) patients were alive with functional leads at the time of last follow-up. Patients with failed leads had higher BMI (p = 0.07), better functional status (p = 0.04), higher serum creatinine (p = 0.004), wider QRS complex (p = 0.01), higher number of implanted leads (p = 0.06) and were more likely to have ischemic cardiomyopathy (p = 0.03). After adjusting for these variables in a binary logistic regression model, only a lower BMI, presence of non-ischemic cardiomyopathy, and a better functional status remained independently predictive of electrical failure.ConclusionsOnly 2.3% of non-recalled ICD leads experience electrical failure (annual failure rate of 0.6%). A higher patient functional status, lower BMI, and non-ischemic etiology of cardiomyopathy are independently associated with higher rates of ICD lead failure.     

Incidence of lead dislodgement,malfunction and perforation during the first year following device implantation

Background

The number of cardiac rhythm device implantations has been growing fast due to expanding indications and ageing of the population. Complications of implantation were rare in the trials. However, these involved small numbers and selected patients. Prospective real-life data are necessary to assess cardiac device implantation procedure-related risks.

Objective

To determine the incidence and predictors of lead-related re-intervention in a Dutch high-volume teaching hospital.

Methods

Data from all patients who underwent cardiac rhythm device implantation between January 2010 and December 2011 were collected in a prospective registry. At least 1 year of follow-up regarding re-intervention was available for all patients. Lead-related reasons for re-intervention were categorised into lead dislodgement, malfunctioning or perforation.

Results

One thousand nine hundred twenty-nine devices including 3909 leads were implanted. In 595 patients (30.8 %) a CRT-D/P was implanted. Lead-related re-intervention was necessary in 86 (4.4 %) patients; it was more common in younger and male patients, and due to either lead dislodgement (66 %), malfunctioning (20 %) or perforation (18 %). Coronary sinus lead dislodgement or malfunctioning was 1.4 %. Right atrial dislodgement (1.9 %, p < 0.001) or ICD lead dislodgement (1.8 %, p = 0.002) was more common than right ventricular dislodgement (0.3 %). The incidence of lead malfunctioning was higher (0.8 %) in ICD leads. An apical position of the right ventricular lead and lateral wall position of the right atrial lead were related to cardiac perforation.

Conclusions

The incidence of lead-related re-intervention was comparable with the literature. The majority of re-interventions were due to lead dislodgements, particularly with right atrial and ICD leads. Re-intervention due to coronary sinus lead dislodgement was rare.     

Ultrasound-guided axillary vein puncture for cardiac devices implantation in patients under antithrombotic therapy

BackgroundUltrasound-guided axillary venous puncture (UGAVP) for cardiac devices implantation has been developed because of its rapidity, safety and potential long-term lead protection. Early work excluded defibrillators (ICD), cardiac resynchronization therapy (CRT) and upgrade procedures. Compared to the cephalic approach, in previous studies, there was a greater use of pressure dressings with this technique, suggesting a higher risk of bleeding.AimsTo assess UGAVP in patients under antithrombotic therapy (ATT) undergoing cardiac devices implantation including CRT/ICD.MethodsProspectively, consecutive patients eligible for a pacemaker or ICD implantation were included. All procedures were performed by a single operator, experienced with UGAVP for femoral access, and fluoroscopy-guided axillary vein access. Guidewires insertion time (from lidocaïne administration), and complications were systematically studied.ResultsFrom 457 cardiac device implantations, 200 patients (77.8 ± 10 y, male 58%) 360 leads were implanted by UGAVP including 36 ICD, 54 CRT and 14 upgrade procedures. A majority (90%) was under ATT: Vitamin K Antagonist or Heparin (n = 58, 29%), direct oral anticoagulant (n = 46, 23%), dual antithrombotic therapy (n = 18, 9%) and single antiplatelet drug (n = 82, 41%). UGAVP was successful in 95.78%. Mean insertion time for 1.8 guidewires per patient was 4.68 ± 3.6 min. No complication (no hematoma) was observed during the follow-up (mean of 45 ± 10 months). Guidewires insertion time reached its plateau after 15 patients.ConclusionUGAVP is fast, feasible and safe for patients under ATT undergoing device implantation including CRT/ICD and upgrade procedures, with a short learning curve.     

The automatic external cardioverter-defibrillator

In-hospital cardiac arrest remains a major problem but new technologies allowing fully automatic external defibrillation are available. These technologies allow the concept of "external therapeutic monitoring" of lethal arrhythmias. Since early defibrillation improves outcome by decreasing morbidity and mortality, the use of this device should improve the outcome of in-hospital cardiac arrest victims. Furthermore, the use of these devices could allow safe monitoring and treatment of patients at risk of cardiac arrest who not necessarily must be in conventional monitoring units (Intensive or Coronary Care Units) saving costs with a more meaningful use of resources. The capability to provide early defibrillation within any patient-care areas should be considered as an obligation ("standard of care") of the modern hospital.     

The need for studies to evaluate the reproducibility of the T-wave alternans (TWA), and the rationale for a correction index of the TWA

Sudden cardiac death (SCD) due to various cardiomyopathies is currently prevented by the implantation of an automated cardioverter/defibrillator (ICD). ICD impalntation in patients who are not survivors of SCD, or have not suffered potentially lethal ventricular arrhythmias, are based on the presence of cardiomyopathy with a reduced left ventricular ejection fraction. The bulk of patients who are considered suitable for an ICD implantation and receive such devices, do not experience device therapy shocks at follow-up ("false positives"), thus creating a climate of uncertainty among patients and physicians about the soundness of our current eligibility criteria for ICDs. In addition the cost of inappropriate ICDs is staggering, and the undue exposure of "false positive" patients to complications, and hardships is disconcerting. T-wave alternans (TWA) has emerged as a possible "risk detection of SCD" technology, but its reproducibility has not been tested. Peripheral edema (extracardiac) or other cardiac mechanisms, unrelated to the degree of SCD risk, alter the amplitude, and other attributes, of the T-waves. Since TWA may be T-wave amplitude-, or other T-wave attributes-dependent (this is still a speculation), a need may be emerging for its correction by the T-wave amplitude (TWA index); such an index may enhance the reproducibility, and evaluate the true sensitivity, specificity and predictive accuracy of the TWA in detecting future victims of SCD.     

Epicardial fat pad within the transverse sinus mimicking a left atrial appendage thrombus

The presence of left atrial thrombus is a contraindication to cardioversion or catheter ablation in patients with atrial fibrillation, due to the increased risk of systemic thromboembolism. Management of this situation includes changes in the anticoagulation regimen and repeat imaging tests. Accurate diagnosis of left atrial appendage thrombus is therefore essential but can sometimes be challenging. Multiple imaging modalities may sometimes be required in the setting of anatomical variations of the left atrial appendage and surrounding structures.We present the case of a patient awaiting ablation for atypical atrial flutter, who underwent a transthoracic echocardiogram that showed an echodense, mobile structure within the vicinity of the left atrial appendage, suggesting a possible thrombus. A cardiac CT demonstrated the image to correlate with an epicardial fat pad within the transverse sinus.     

High Defibrillation Threshold: The Science,Signs and Solutions

Defibrillation threshold (DFT) testing has traditionally been an integral part of implantable cardioverter defibrillator (ICD) implantation. With the increasing number of patients receiving ICDs, physicians are encountering high DFT more often than before. Tackling the problem of high DFT, warrants an in-depth understanding of the science of defibrillation including the key electrophysiological concepts and the underlying molecular mechanisms. Numerous factors have been implicated in the causation of high DFT. Due consideration to the past medical history, pharmacotherapy, laboratory data and cardiac imaging, help in assessing the pre-procedural risk for occurrence of high DFT. Drugs, procedural changes, type and location of ICD lead system are some of the key players in predicting DFT during implantation. In the event of encountering an unacceptably high DFT, we recommend to follow a step-wise algorithm. Ruling out procedural complications like pneumothorax and tamponade is imperative before embarking on a search for potentially reversible clinical or metabolic derangements. Finally, if these attempts fail, the electrophysiologist must choose from a wide range of options for device adjustment and system modification. Although this review article is meant to be a treatise on the science, signs and solutions for high DFT, it is bound by limitations of space and scope of the article.