Dual-chamber Implantable Cardioverter Research Articles

Unique Tachycardia Recorded on a Cardiac Implantable Electronic Device: What is the Mechanism?

In a 55-year-old man with nonischemic cardiomyopathy, a unique tachycardia was recorded on a dual-chamber implantable cardioverter defibrillator (St. Jude Medical [Abbott]) as an automatic mode switch episode. This case report discusses the mechanism of tachycardia, how it can be differentiated from similar rhythms, and its clinical implications. The report explores device limitations in managing such tachycardias and presents reprograming strategies to prevent recurrence. This case emphasizes the importance of careful analysis of device-mediated arrhythmias and appropriate programming.

Single- vs dual-chamber ICDs to prevent from inappropriate shocks: the debate is still alive

Abstract Background The efficacy of dual-chamber implantable cardioverter defibrillators (ICDs) in preventing from inappropriate shocks (IS) is still a matter of debate. Purpose To compare the risk of IS among single- and dual-chamber ICDs in a cohort of heart failure (HF) patients carrying a prophylactic device. We aimed to focus on the relationship between programming and discriminators, and the risk of IS in a large cohort. Methods All HF patients with left ventricle ejection fraction <35% undergoing a prophylactic ICD-only implant were collected from the multicentre, prospective and nationwide UMBRELLA study. ICD programming was performed according to regular clinical practice at each site and. ICD setting and arrhythmic events occurring during the study period were automatically stored through the remote monitoring system. An experts committee analysed in a blinded manner all electrograms coming from the arrhythmic events. Results From 2006 to 2015, 782 patients implanted with an ICD were analysed (537 patients (68.7%) with single-chamber ICDs and 245 patients (31.3%) with dual-chamber ICDs). During a mean follow-up of 4.35±2 years, 109 IS were delivered in 49 patients. IS occurred in 7.8% (n=42) of patients carrying single-chamber ICDs and in 2.9% (n=7) of dual-chamber carriers (p=0.001). A propensity score matched analysis was performed. The matched cohort was composed by 110 well-balanced (regarding baseline characteristics and programming) patients. In the weighted sample, dual-chamber ICDs were related to lower rates of IS (Figure 1) as compared to single-chamber devices (0.9% vs. 11.8%, p≤0.001). Among programming the following ICD settings correlated to lower risk of IS: ≥30 of 40 intervals detection within ventricular fibrillation (VF) zone (HR=0.47; p=0.018), a programmed ATP-capable zone enabled through VF zone (HR=0.54; p=0.038), morphology discriminator (Wavelet®) (HR=0.42; p=0.032), and the specific dual-chamber discriminator (PR Logic®) (HR=0.28; p=0.004). After multivariable Cox regression analysis including clinical variables and device settings, PR Logic® discriminator was the only programming parameter independently related to a lower risk of IS (HR=0.18, CI 0.06–0.48, p=0.001). Conclusions In our nationwide cohort of primary prevention ICD-only patients, dual-chamber devices were associated with a lower risk of IS. ICDs equipped with PR Logic® discriminator might be useful to prevent from IS. Funding Acknowledgement Type of funding sources: None. Programming in the matched populationFigure 1

Azygos Vein ICD Lead Implantation Lowers Defibrillation Threshold in a Patient with Hypertrophic Cardiomyopathy

A 14-year-old boy with hypertrophic cardiomyopathy (HCM) diagnosed at the age of 1 year and with massive left ventricular hypertrophy suffered an episode of ventricular fibrillation during mild effort. He underwent a dual-chamber implantable cardioverter defibrillator (ICD) implantation. The defibrillation threshold testing (DFT) was ineffective. Subcutaneous multi-coli arrays tunneled into the left postero-lateral position and connected to the superior vena cava (SVC) port of the dual-chamber ICD were added to increase the myocardial mass involved in the defibrillation shock pathway. A new DFT was unsuccessful. The patient was transferred to our hospital for myectomy. An epicardial defibrillation patch was placed on the left ventricular lateral wall, but again, DFT testing was ineffective using the right ventricular (RV) coil to lateral patch as shock pathway. Another epicardial defibrillation patch was then placed on the inferior wall. In this case, DFT testing was effective with a defibrillation pathway between the two patches and the can. In November 2015, a high shock impedance alarm was recorded through remote monitoring, thus compromising the safety of the ICD shock pathway. The patient underwent the implant of a new trans-venous defibrillation coil lead in the azygos vein. After few months, the patient developed symptomatic severe aortic regurgitation and underwent an aortic valve replacement. During the operation, DFT testing was performed and was successful. Our case illustrates that azygous vein ICD lead implantation is efficacious in HCM with massive hypertrophy and high DFT, and prompts further studies to systematically investigate its efficacy in this particular subgroup of the HCM population.

Abandoned and fractured ICD lead with complete superior veins occlusion: Is transvenous lead extraction still possible?

An 86-year-old male patient was referred to our institution for transvenous lead extraction (TLE) after a recent unsuccessful attempt in another center. The patient with a history of hypertension, coronary artery bypass grafting, ischemic cardiomyopathy, permanent atrial fibrillation, and chronic renal impairment, underwent an implantation of a dual-chamber implantable cardioverter defibrillator (ICD) for primary prevention of sudden cardiac death in 2011. This article is protected by copyright. All rights reserved.

GW29-e0243 Comparison study on sensing and identification of Single-Lead Atrial Sensing System, Single-Chamber and Dual-Chamber Implantable Cardioverter Defibrillator System

The study was performed to evaluate the postoperative parameters stability, classified ventricular arrhythmia sensibility and supraventricular arrhythmia specificity on Single-Lead Atrial Sensing System, Single-Chamber (VR) and Dual-Chamber (DR) Implantable Cardioverter Defibrillator (ICD) System,

Subaxillary approach to cardiac electronic device implantation using a single surgical incision: a single-centre experience.

Pacemakers and implantable cardioverter defibrillators have become more common in younger individuals, owing to broader indications and technological advances. Our goal was to report our long-term experience of implanting cardiac devices in young adults via a subaxillary approach with a hidden single incision, to minimize the aesthetic impact of the device. From 2003 to 2012, 23 patients underwent cardiac device implantation via a subaxillary approach while they were under general anaesthesia. The axillary vein was punctured under contrast-medium radiological guidance. The devices were positioned into the pocket under the pectoralis major muscle and over the fascia that envelopes the pectoralis minor muscle, through a lateral surgical access along the midaxillary line. Twenty-two single- and dual-chamber implantable cardioverter defibrillator and 1 dual-chamber pacemaker were implanted (mean age 32.2 ± 13.4 years). All procedures were successfully performed without complications; overall hospitalization after implantation was 3.3 days. During mean a follow-up of 65 ± 18 months, no deaths, infections or device migrations occurred. Two ventricular lead dislodgements requiring repositioning occurred within 1 month, and 1 defibrillation lead fracture occurred 5 years after implantation. All patients were extremely satisfied with the aesthetic result. A mild increase in the pacing threshold (0.88 ± 0.6 V at 0.4/0.5 ms at implantation vs 1.00 ± 0.3 V at 0.4/0.5 ms at 2-year follow-up, P = 0.063) and a statistically significant decrease in the pacing impedance (637 ± 161 ohm at implantation vs 499 ± 81 ohm at 2-year follow-up, P = 0.001) were observed, without any consequences. The subaxillary approach is a safe, feasible technique that requires a simple surgical procedure. The implantable cardioverter defibrillator functions properly at implantation and at long-term follow-up.

Can machine learning complement traditional medical device surveillance? A case study of dual-chamber implantable cardioverter-defibrillators.

BackgroundMachine learning methods may complement traditional analytic methods for medical device surveillance.Methods and resultsUsing data from the National Cardiovascular Data Registry for implantable cardioverter–defibrillators (ICDs) linked to Medicare administrative claims for longitudinal follow-up, we applied three statistical approaches to safety-signal detection for commonly used dual-chamber ICDs that used two propensity score (PS) models: one specified by subject-matter experts (PS-SME), and the other one by machine learning-based selection (PS-ML). The first approach used PS-SME and cumulative incidence (time-to-event), the second approach used PS-SME and cumulative risk (Data Extraction and Longitudinal Trend Analysis [DELTA]), and the third approach used PS-ML and cumulative risk (embedded feature selection). Safety-signal surveillance was conducted for eleven dual-chamber ICD models implanted at least 2,000 times over 3 years. Between 2006 and 2010, there were 71,948 Medicare fee-for-service beneficiaries who received dual-chamber ICDs. Cumulative device-specific unadjusted 3-year event rates varied for three surveyed safety signals: death from any cause, 12.8%–20.9%; nonfatal ICD-related adverse events, 19.3%–26.3%; and death from any cause or nonfatal ICD-related adverse event, 27.1%–37.6%. Agreement among safety signals detected/not detected between the time-to-event and DELTA approaches was 90.9% (360 of 396, k=0.068), between the time-to-event and embedded feature-selection approaches was 91.7% (363 of 396, k=−0.028), and between the DELTA and embedded feature selection approaches was 88.1% (349 of 396, k=−0.042).ConclusionThree statistical approaches, including one machine learning method, identified important safety signals, but without exact agreement. Ensemble methods may be needed to detect all safety signals for further evaluation during medical device surveillance.

Economic impact of longer battery life of cardiac resynchronization therapy defibrillators in Sweden.

ObjectiveThe objective of this study was to quantify the impact that longer battery life of cardiac resynchronization therapy defibrillator (CRT-D) devices has on reducing the number of device replacements and associated costs of these replacements from a Swedish health care system perspective.MethodsAn economic model based on real-world published data was developed to estimate cost savings and avoided device replacements for CRT-Ds with longer battery life compared with devices with industry-standard battery life expectancy. Base-case comparisons were performed among CRT-Ds of three manufacturers – Boston Scientific Corporation, St. Jude Medical, and Medtronic – over a 6-year time horizon, as per the available clinical data. As a sensitivity analysis, we evaluated CRT-Ds as well as single-chamber implantable cardioverter defibrillator (ICD-VR) and dual-chamber implantable cardioverter defibrillator (ICD-DR) devices over a longer 10-year period. All costs were in 2015 Swedish Krona (SEK) discounted at 3% per annum.ResultsBase-case analysis results show that up to 603 replacements and up to SEK 60.4 million cumulative-associated costs could be avoided over 6 years by using devices with extended battery life. The pattern of savings over time suggests that savings are modest initially but increase rapidly beginning in the third year of follow-up with each year’s cumulative savings two to three times the previous year. Evaluating CRT-D, ICD-VR, and ICD-DR devices together over a longer 10-year period, the sensitivity analysis showed 2,820 fewer replacement procedures and associated cost savings of SEK 249.3 million for all defibrillators with extended battery life.ConclusionExtended battery life is likely to reduce device replacements and associated complications and costs, which may result in important cost savings and a more efficient use of health care resources as well as a better quality of life for heart failure patients in Sweden.

Acute Myocardial Infarction with Isolated Congenitally Corrected Transposition of the Great Arteries

Congenital cardiac abnormalities diagnosed at the time of acute coronary syndrome are rare. A 43-year-old man presented to the emergency department complaining of recurring, severe chest pain. Subsequent emergent coronary angiography demonstrated unusual coronary anatomy: 1) one small caliber bifurcating vessel originating from the right sinus of Valsalva; 2) one very large vessel arising from the posterior sinus; and 3) no coronary artery from the normal left sinus of Valsalva. The large vessel from the posterior sinus was totally occluded in its midportion and was treated with intravascular ultrasound-guided percutaneous coronary intervention. Further diagnostic workup, including two-dimensional transthoracic echocardiogram and computed tomographic coronary angiography, demonstrated isolated corrected transposition of the great arteries with a dilated systemic ventricle and systolic dysfunction with an ejection fraction of 30%. The patient's clinical course was complicated by recurrent nonsustained ventricular tachycardia, treated with medical therapy and a dual-chamber implantable cardioverter defibrillator. This case is an example of a common clinical presentation with a very uncommon congenital heart disorder. Similar cases may become more frequent as the number of adult congenital heart patients increases in the population.

Outcomes of single- or dual-chamber implantable cardioverter defibrillator systems in Japanese patients

BackgroundThere are no criteria for selecting single- or dual-chamber implantable cardioverter defibrillators (ICDs) in patients without a pacing indication. Recent reports showed no benefit of the dual-chamber system despite its preference in the United States. As data on ICD selection and respective outcomes in Japanese patients are scarce, we investigated trends regarding single- and dual-chamber ICD usage in Japan. MethodsData from a total of 205 ICD recipients with structural heart disease (median age, 63 years) in two Japanese university hospitals were reviewed. Patients with bradycardia with a pacing indication and permanent atrial fibrillation at implantation were excluded. ResultsSingle- and dual-chamber ICDs were implanted in 36 (18%) and 169 (82%) patients, respectively. Non-ischemic cardiomyopathy dominated both groups. Seventeen dual-chamber patients developed atrial pacing-dependency over 4.5 years, and it developed immediately after implantation in 14. Although preoperative testing showed no sign of bradycardia in these patients, their pacing rate was set higher than it was in patients who were pacing-independent (61 vs. 46 paces per min, p<0.01). Two single-chamber patients (5%) underwent atrial lead insertion.While inappropriate shock equally occurred in both groups (7 vs. 21 patients, single- vs. dual-chamber, P=0.285), device-related infection occurred only in dual-chamber patients (0 vs. 9 patients, P=0.155). No differences in death or heart failure hospitalization were observed between groups. ConclusionsDual-chamber ICDs were four-fold more common in Japanese patients without a pacing indication. No benefit over single-chamber ICD was observed. Newly developed atrial pacing-dependency seemed to be limited and could have been overestimated due to higher pacing rate settings in dual-chamber patients.

Right Ventricular Septal Pacing: In Lieu of Biventricular Pacing for Cardiac Resynchronization in a Patient With Right Bundle Branch Block? *

A 71-year-old male with ischemic cardiomyopathy, severe systolic left ventricular dysfunction and symptomatic heart failure was not considered a good candidate for implantation of a biventricular pacing system to effect cardiac resynchronization due to underlying right bundle branch block (RBBB). He received instead a dual-chamber implantable cardioverter defibrillation with the ventricular lead placed at an alternate site position at the high right ventricular septum. This resulted in significant narrowing of the QRS duration (resynchronization) with a good clinical response over short-term. The case illustrates a possible alternative approach to biventricular pacing for cardiac resynchronization in patients with RBBB.

A case study of a 59-year-old male with a cardiac variant of Anderson–Fabry disease

Anderson–Fabry disease is a rare X-linked lysosomal storage disorder caused by deficiency of the enzyme alpha-galactosidase A, affecting around 1 in 100,000 births. Waste products build up within cells throughout the body, affecting the heart, nervous system, skin, eyes and kidneys. In the cardiac variant, Anderson–Fabry disease the effects are limited to the heart, causing left-ventricular hypertrophy (LVH), valve defects and conduction abnormalities. Involvement of the heart contributes to morbidity and premature death because of increased prevalence of heart failure, arrhythmia and strokes. Utilising a case study of a 59-year-old male with the cardiac variant of Anderson–Fabry disease, this article discusses the treatment options available, including dual chamber pacing and implantable cardioverter defibrillator (ICD) therapy, in line with American Heart Association/American College of Cardiology (AHA/ACC) guideline criteria. Additionally research into enzyme replacement therapy (ERT) suggests treatment can reverse damage and prevent further damage occurring, therefore the use of ERT and its effectiveness in this case is also discussed.

Dramatic improvement of refractory anemia caused by mechanical hemolysis in a patient with hypertrophic obstructive cardiomyopathy using dual-chamber pacing

A 59-year-old woman with hypertrophic obstructive cardiomyopathy was admitted to our institution with worsening heart failure. She developed mechanical intracardiac hemolysis due to left ventricular outflow tract (LVOT) obstruction. Despite surgical myectomy, the LVOT pressure gradient (PG) remained high and hemolytic anemia recurred. A dual-chamber implantable cardioverter defibrillator was then implanted, which decreased the LVOT-PG and improved hemolysis.

Do patients with heart failure and right bundle branch block need biventricular pacing? A case of significant QRS narrowing by right ventricular pacing alone

We report the case of a 56-year-old male with ischemic cardiomyopathy, severe left ventricular dysfunction and right bundle branch block (RBBB) with a wide QRS duration (180ms) who received dual-chamber implantable cardioverter–defibrillator for primary prevention of sudden death. After having placed the right ventricular lead in the middle of the inter-ventricular septum, a significant narrowing of QRS duration was observed, thus obtaining “de facto” a cardiac resynchronization therapy (CRT). This type of cardiac pacing could be an alternative to conventional CRT with left ventricular pacing in patients with wide QRS due to RBBB. The long-term effects of this RV only pacing strategy with ICD in patients with heart failure yet remain to be determined.

Implantable cardioverter defibrillator system with floating atrial sensing dipole: a single-center experience.

The concept of a single-lead dual-chamber implantable cardioverter defibrillator (ICD) with floating sensing atrial dipole has been proven safe and functional. We report a single-center experience with this ICD system; the major focus of the work is on the recorded atrial activation and its stability on a medium term follow-up. Thirteen patients received a DX ICD (BIOTRONIK SE & Co, Berlin, Germany) with the Linox Smart S DX(ProMRI) ICD lead; the implantation data were reported. Daily P- and R-wave sensing amplitude was collected and followed up during 200 days; their coefficient of variance (CV) was calculated. In addition, all the atrial and ventricular high-rate episodes were analyzed. The total x-ray exposure time was 3.9 ± 1.8 minutes. The overall mean sensing was 4.2 ± 1.9 mV for P wave and 12.9 ± 4.5 mV for R wave. The CV was significantly higher for the P-wave amplitude than for the R-wave one (0.25 ± 0.11 vs 0.08 ± 0.06; P < 0.001). A total of 27 high ventricular rate episodes were recorded and correctly discriminated by the device. Fifty-six high atrial rate episodes were recorded, 49 were true arrhythmic events. The single-lead ICD system with floating atrial dipole provides reliable atrial sensing amplitude over time. The physician, without the implantation of an additional lead, has the atrial information that may be used for the discrimination of supraventricular tachyarrhythmia/ventricular tachycardia, for the early detection of atrial fibrillation episodes and for the evaluation of changes in the patient's heart status.

A case of in vivo thrombogenicity of an externalized Riata ST lead

A 67-year-old man who had undergone implantation of a dual-chamber implantable cardioverter defibrillator (ICD) with a Riata lead, model #7020 (St Jude Medical) in 2007, 3 months ago presented with deterioration of heart failure. Interrogation of the ICD showed an …

Inappropriate Shocks in Patients with ICDs: Single Chamber versus Dual Chamber

BackgroundDespite the technological evolution of the implantable defibrillator, one of the questions that remains is the possible benefit of the dual chamber versus single chamber implantable cardioverter defibrillator (ICD) in reducing inappropriate shocks.ObjectiveTo evaluate which type of device provides fewer inappropriate shocks (dual chamber versus single chamber) in patients with implantable cardioverter defibrillators (ICDs).MethodsMeta-analysis of randomized studies published in the literature comparing dual-chamber implantable cardioverter defibrillators to single chamber devices which have been known to cause, as an evaluated endpoint, inappropriate shocks. ResultsThe dual-chamber implantable cardioverter showed no benefit in reducing the number of inappropriate shocks. In fact, the opposite was shown. In the analysis of fixed effects, the association tended to favor single-chamber implantable cardioverter defibrillators (OR = 1.53, CI 95%: 0.91-2.57), despite the absence of statistical significance (p = 0.11). We highlight the heterogeneity observed in the results (I2 = 53%), which motivated a replication of the analysis using a model of random effects. However, significant differences remained in the occurrence of inappropriate shocks in both groups (OR = 1.1, 95% CI: 0.37-3.31; p = 0.86). To complement the analysis, we proceeded to perform sensitivity analysis, which showed that the exclusion of a study resulted in the lowest heterogeneity observed (I2=24%) and the association with inappropriate shocks significantly favored the single chamber cardiodefibrillator (OR = 1.91; 95% CI: 1.09-3.37; p = 0.27).ConclusionsIt was determined that there was no clear evidence of superiority of any of the devices evaluated.

Decrease of the right ventricular electrogram amplitude in a Sprint Fidelis shock lead: a sign of lead malfunction?

A 76-year-old male had dual-chamber implantable cardioverter defibrillatorimplanted, employing a Medtronic Sprint Fidelis 6931-65 shock. A routine follow-up 4 years later showed a sudden steep decrease in the amplitude of the right ventricular electrogram (EGM) from 9.0 to 2.0 mV ( Panel A ). Because of the known high failure rate related to the Sprint Fidelis shock lead, we initially focused on markers of lead failure by recordings of the intracardiac EGM, changes in …

Monitoring zone-associated implantable cardioverter defibrillator shock: A case report

A 41-year-old man with Brugada syndrome, who had been implanted with an ATLAS+DR V-243 (St. Jude Medical, Inc., St. Paul, MN, USA) dual-chamber implantable cardioverter defibrillator (ICD) for secondary prevention of arrhythmia, received an inappropriate shock. The ventricular fibrillation (VF) zone was programmed to deliver maximum output shock therapy at a detection threshold of greater than 214 beats per min, and 12 consecutive instances of crossing the threshold constituted 1 VF. The monitoring zone was programmed to detect heart rates of greater than 160 beats per min with all supraventricular tachycardia (SVT) discriminators in the “ON” mode, and 12 consecutive instances of the heart rate exceeding 160 beats per min constituted 1 SVT. The ICD shock was delivered after an episode of sinus tachycardia that continued for 3min 15s. The monitoring zone is effective for detecting asymptomatic ventricular tachycardia or SVT, and therapy is not usually set up in this zone. Here, we report the possibility that in some patients implanted with certain types of ICD devices, the monitoring zone may become a factor in the delivery of an inappropriate shock.

Is a Dual-Chamber ICD Always Better in Patients Requiring an ICD?

Dual-chamber implantable cardioverter defibrillators (ICDs) offer specific advantages and programming flexibility that single-chamber ICDs cannot. The ICD of choice for the patient who has an indication for an ICD but does not need cardiac resynchronization therapy is a dual-chamber ICD in most cases.