Antitachycardia pacing programming in implantable cardioverter defibrillator:A systematic review

Implantable cardioverter defibrillator(ICD) programminginvolves several parameters. In recent years antitachycardia pacing(ATP) has gained an increasing importance in the treatment of ventricular arrhythmias, whether slow or fast. It reduces the number of unnecessary and inappropriate shocks and improves both patient's quality of life and device longevity. There is no clear indication regarding the type of ATP to be used, except for the treatment of fast ventricular tachycardias(188 bpm-250 bpm) where it has been shown a greater efficacy and safety of burst compared to ramp; 8 impulses in each sequence of ATP appears to be the best programming option in this setting. Beyond ATP use, excellent clinical results were obtained with programming standardization following these principles: extended detection time in ventricular fibrillation(VF) zone; supraventricular discrimination criteria up to 200 bpm; first shock in VF zone at the maximum energy in order to reduce the risk of multiple shocks. The MADIT-RIT trial and some observational registries have also recently demonstrated that programming with a widespread use of ATP, higher cut-off rates or delayed intervention reduces the number of inappropriate and unnecessary therapies and improves the survival of patients during mid-term follow-up.

Induced atrial fibrillation during defibrillation test on implantation of subcutaneous implantable cardioverter defibrillator

The subcutaneous implantable cardioverter defibrillator(S-ICD)has become an alternative to the transvenous ICD in indicated patients.However,inappropriate shock or failed ventricular tachycardia/fibrillation conversion is the most alarming complication of S-ICD.Therefore,defibrillation test(DFT)is recommended for the S-ICD implantation.

NYHA Class II or III Heart Failure: Who Will Need an Implantable Cardioverter Defibrillator (ICD)?

Sudden cardiac death (SCD) is one of the most debilitating and life-threatening complications of heart failure (HF) which has challenged medical care for long. Current guidelines suggest the use of Implantable Cardioverter Defibrillator (ICD) in primary prevention of SCD in both New York Heart Association (NYHA) class II and class III heart failure. This paper critically evaluated the evidence underlying the guideline recommendation. In contrast to recent guidelines, the majority of the intervention trials conducted on the topic till date found a promising role of ICD only in the prevention of SCD in NYHA class II HF. One of the trials which found a significant role of ICD in type III heart failure was underpowered. Thus, further trials are needed to validate the use of ICD in the prevention of SCD in type III HF.

Impact of LDB3 gene polymorphisms on clinical presentation and implantable cardioverter defibrillator(ICD) implantation in Chinese patients with idiopathic dilated cardiomyopathy

Objective:Mutations in LIM domain binding 3(LDB3)gene cause idiopathic dilated cardiomyopathy(IDCM),a structural heart disease with a complicated genetic background.However,the association of polymorphisms in the LDB3 gene with susceptibility to IDCM in Chinese populations remains unexplored as dose the impact on clinical presentation.Methods:We sequenced all exons and the adjacent part of introns of the LDB3 gene in 159 Chinese Han IDCM patients and 247 healthy controls.Then we detected the distribution of polymorphisms in the LDB3 gene in all participants and assessed their associations with risk of IDCM.Additionally,we conducted a stratified genotype–phenotype correlation analysis.Results:The A allele of rs4468255 was significantly associated with IDCM(P<0.01).The rs4468255,rs11812601,rs56165849,and rs3740346 were also associated with diastolic blood pressure(DBP)and left ventricular ejection fraction(LVEF)(P<0.05).Notably,a higher frequency of rs4468255 polymorphism was observed in implantable cardioverter defibrillator(ICD)recipients under a recessive model(P<0.01),whereas the significant association disappeared after adjusting for potential confounders.However,in the dominant model,notable correlations could only be observed after adjusting for multi parameters.Conclusions:The rs4468255 was significantly correlated with IDCM of Chinese Han population.A allele of rs4468255 is higher in IDCM patients with ICD implantation,suggesting the influence of genetic background in the generation of this response.In addition,rs11812601,rs56165849,and rs3740346 in LDB3 show association with brain natriuretic peptide,DBP,and LVEF levels in patients with IDCM but did not show any association with IDCM susceptibility.

Critical analysis of ineffective post implantation implantable cardioverter-defibrillator-testing

AIM To test of the implantable-cardioverter-defibrillator is done at the time of implantation. We investigate if any testing should be performed.METHODS All consecutive patients between January 2006 and December 2008 undergoing implantable cardioverterdefibrillator(ICD) implantation/replacement(a total of 634 patients) were included in the retrospective study.RESULTS Sixteen patients(2.5%) were not tested(9 with LA/LVthrombus, 7 due to operator's decision). Analyzed were 618 patients [76% men, 66.4 + 11 years, 24% secondary prevention(SP), 46% with left ventricular ejection fraction(LVEF) < 20%, 56% had coronary artery disease(CAD)] undergoing defibrillation safety testing(SMT) with an energy of 21 + 2.3 J. In 22/618 patients(3.6%) induced ventricular fibrillation(VF) could not be terminated with maximum energy of the ICD. Six of those(27%) had successful SMT after system modification or shock lead repositioning, 14 patients(64%) received a subcutaneous electrode array. Younger age(P = 0.0003), non-CAD(P = 0.007) and VF as index event for SP(P = 0.05) were associated with a higher incidence of ineffective SMT. LVEF < 20% and incomplete revascularisation in patients with CAD had no impact on SMT.CONCLUSION Defibrillation testing is well-tolerated. An ineffective SMT occurred in 4% and two third of those needed implantation of a subcutaneous electrode array to passa SMT > 10 J.

Effect of primary prevention of implantable cardioverter defibrillator on sudden cardiac death in 24 patients with dilated cardiomyopathy

Objective To study the effect of primary prevention of implantable cardioverter defibrillator(ICD)on sudden cardiac death(SCD)in patients with dilated cardiomyopathy.Methods A total of 36 patients with dilated cardiomyopathy treated in our hospital from 2013-12 to2014-12 were studied including 29(80.6%)male and 7(19.4%)female with the mean age of(63±11.8)

Remote monitoring of implantable defibrillators is associated with fewer inappropriate shocks and reduced time to medical assessment in a remote and rural area

BACKGROUND Implantable cardioverter defibrillators(ICDs)and cardiac resynchronisation therapy with defibrillators(CRT-D)reduce mortality in certain cardiac patient populations.However,inappropriate shocks pose a problem,having both adverse physical and psychological effects on the patient.The advances in device technology now allow remote monitoring(RM)of devices to replace clinic follow up appointments.This allows real time data to be analysed and actioned and this may improve patient care.AIM To determine if RM in patients with an ICD is associated with fewer inappropriate shocks and reduced time to medical assessment.METHODS This was a single centre,retrospective observational study,involving 156 patients implanted with an ICD or CRT-D,followed up for 2 years post implant.Both appropriate and inappropriate shocks were recorded along with cause for inappropriate shocks and time to medical assessment.RESULTS RM was associated with fewer inappropriate shocks(13.6%clinic vs 3.9%RM;P=0.030)and a reduced time to medical assessment(15.1±6.8 vs 1.0±0.0 d;P<0.001).CONCLUSION RM in patients with an ICD is associated with improved patient outcomes.

A MEDIAN FOLLOW-UP OF TWENTY-TWO MONTHS FOR CARDIOVERTER DEFIBRILLATOR IMPLANTATION IN SYMPTOMATIC OR ASYMPTOMATIC PATIENTS WITH BRUGADA SYNDROME

Objective To explore the outcome of patients with Brugada syndrome by remedial or prophylactic implantable cardioverter defibrillator （ ICD ） for ventricular tachyarrhythmia. Methods Sixteen single chamber ICDs and 5 double chamber ICDs in 21 consecutive patients [ 17 males, 4 females; mean age, （ 36 ± 11） years ] with Brugada syndrome were involved. Fifteen patients with spontaneous or induced ventricular tachycardia/ventricular fibrillation （VT/VF） received the remedial and prophylactic ICD implantation. Six patients only with positive family history or syncope accepted the ICD implantation for prophylaxis. Results After a median follow-up of （22.3 ± 13. 4） months, all patients were alive. One patient was suspected with febrile syndrome due to endocarditis on the auricular face of the lead of defibrillator 18 months after 1CD implantation and disappearance of vegetation was found after receiving one-month antibiotic treatment. Nine appropriate ICD interventions took place in 3 individuals with documented spontaneous ventricular arrhythmias. Multivariable analysis suggested that occurrence of appropriate interventions was related to the spontaneous ventricular arrhythmias （ P 〈 0. 0001 ）. Eleven inappropriate ICD interventions occurred in 3 patients for atrial fibrillation or atrial flutter with rapid ventricular rate. Multivariable analysis suggested that occurrence of inappropriate interventions was related to documented spontaneous supraventricular arrhythmias （P 〈 O. 0062 ）. All appropriate interventions and inappropriate interventions occurred within six months after ICD implantation. Conclusion Appropriate interventions may associate to spontaneous ventricular arrhythmias before 1CD implantation in patients with Brugada syndrome. Patients may suffer from inappropriate ICD intervention for supraventricular arrhythmias with rapid ventricular rate when they had a history of supraventricular arrhythmias.

Effects of medically generated electromagnetic interference from medical devices on cardiac implantable electronic devices: A review

As cardiac implantable electronic devices(CIED)become more prevalent,it is important to acknowledge potential electromagnetic interference(EMI)from other sources,such as internal and external electronic devices and procedures and its effect on these devices.EMI from other sources can potentially inhibit pacing and trigger shocks in permanent pacemakers(PPM)and implantable cardioverter defibrillators(ICD),respectively.This review analyzes potential EMI amongst CIED and left ventricular assist device,deep brain stimulators,spinal cord stimulators,transcutaneous electrical nerve stimulators,and throughout an array of procedures,such as endoscopy,bronchoscopy,and procedures involving electrocautery.Although there is evidence to support EMI from internal and external devices and during procedures,there is a lack of large multicenter studies,and,as a result,current management guidelines are based primarily on expert opinion and anecdotal experience.We aim to provide a general overview of PPM/ICD function,review documented EMI effect on these devices,and acknowledge current management of CIED interference.

Transvenous pectoral implantation of single lead implantable cardioverter defibrillator

Objective To report our initial experience of transveneous pectoral implantation of single lead implantable cardioverter defibrillator (ICD) in fifteen patients. Methods Fifteen patients (male 13, female 2, mean age of 51.7 years), including dilated cardiomyopathy in 4, hypertrophic cardiomyopathy in 2, coronary artery disease in 5 and syncope of unknown etiology in 2, underwent ICD implantation. Indications for ICD implantation were ventricular fibrillation (8 patients) and refractory ventricular tachycardia (7 patients). All patients had syncope out of hospital. The ICD system were Medtronic Jewel active can in 5 patients (Model 7219C in 2, 7220C in 3) and CPI Ventak PRxⅢ in 9 patients. For active can, shocks were delivered through distal coil to ICD shell and for PRxⅢ through the endotak lead of proximal to distal coil. Successful implantation criteria was 2 consecutive defibrillation at less than 24 J. Results All 15 patients had successful implantation using single lead ICD system in catheter laboratory. The mean defibrillation threshold was 12.8 J (5-15 J) and R wave was 9.9 mV (3.7-14.6 mV). All devices were of pectoral implantation. No operative and perioperative complications occurred. In 7.6 months (1-18 months) of follow up, 3 patients had VT terminated by antitachycardia pacing (ATP) and 1 patient VF terminated by shock. Conclusion Transveneous pectoral implantation of single lead ICD is easy to perform and has high defibrillation efficacy and should be a preferred approach.

Incidence and causes of inappropriate detection and therapy by implantable defibrillators of cardioversion in patients with ventricular tachyarrhythmia

Background Implantable cardioverter defibrillator （ICD） is the only effective therapy in patients with life threatening ventricular arrhythmias. Inappropriate detection and therapy by ICDs are the most common causes of side effects that affect the quality of life in ICD recipients. This study evaluated the incidence and causes of inappropriate detection and therapy by ICDs in patients in our hospital. Methods From January 2000 to December 2005, fifty patients who received ICD implantation for ventricular arrhythmias for prevention of sudden cardiac death were evaluated in this study. Each ICD was programmed using clinical arrhythmic and cardiac data of the patient before discharge. Patients were followed up by standard schedule after implantation and all data retrieved from each device were collected and saved for further analysis. Results No arrhythmic event was detected in 12/50 （24%） patients during the period of follow-up. Among the remaining patients, 11 （22%） experienced inappropriate detections and therapies during follow-up in this study. ICD detected 383 ventricular tachyarrhythmia （VT） and 108 ventricular fibrillation （VF） episodes and delivered 678 therapies. In VT group, ICD delivered 413 antitachycardiac pacings （ATPs） and 118 shocks, among which 78 ATPs and 9 shocks were initiated by 55/383 （14.3%） inappropriate detections. In VF group ICD delivered 147 shocks, among which 56 shocks were initiated by 28/108 （26.9%） inappropriate detections. Overall, more than 50% of these episodes were caused by atrial fibrillation （AF） with rapid ventricular response, followed by electromagnetic or myopotential interference. In addition, most inappropriate therapies occurred within one year after ICD implantation. Conclusions About one fifth of patients experienced ICD inappropriate detection and therapy after implantation. The main cause was AF with rapid ventricular response, followed by electromagnetic or myopotential interference.

I-123 metaiodobenzylguanidine imaging for predicting ventricular arrhythmia in heart failure patients

Compared to antiarrhythmic drugs, implantable cardioverter defibrillator （ICD） leads to a more significant im- provement in preventing ventricular arrhythmia in heart failure patients. However, an important question has been raised that how to select appropriate patients for ICD therapy. 1-123 metaiodobenzylguanidine （MIBG） planar and SPECT imaging have shown great potentials to predict ventricular arrhythmia in heart failure patients by as- sessing the abnormalities of the sympathetic nervous system. Clinical trials demonstrated that several parameters measured from 1-123 MIBG planar and SPECT imaging, such as heart-to-mediastinum ratio, washout rate, defect score, and innervation/perfusion mismatch, predicted ventricular arrhythmias in heart failure patients. This paper introduces the current practice of ICD therapy and reviews the technical background of 1-123 MIBG planar and SPECT imaging and their clinical data in predicting ventricular arrhythmia.

Riata silicone defibrillation lead with normal electrical measures at routine ambulatory check:The role of highvoltage shock testing

AIM To describe our experience with shock testing for the evaluation of patients with Riata? leads.METHODS Among 51 patients with normal baseline electrical parameters, 20 died during follow-up. Of the remaining 31 patients, 15 underwent the test: In 10 cases a defibrillation testing with ventricular fibrillation(VF) induction and in 5 cases a R-wave-synchronized shock(> 20 J, without inducing VF). The test was performed under sedation with Midazolam. RESULTS Twelve patients(80%) had a normal behavior during shock testing: In 8 cases induced VF was correctly detected and treated; in 4 cases of R-wave-synchronized shock electrical parameters remained stable and normal. Three patients(20%) failed the test. One patient with externalized conductors showed a sudden drop of high-voltage impedance(< 10 Ohm) after a 25 J R-wave-synchronized shock. Two other patients with externalized conductors, undergoing defibrillation testing, showed a short-circuit during shock delivery and the implantable cardioverter defibrillator was unable to interrupt VF.CONCLUSION In Riata? leads the delivery of a low current during routine measurement of high-voltage impedance may not reveal a small short circuit, that can only be evident by attempting to deliver a true shock, either for spontaneous arrhythmias or in the context of a shock testing.

Role of nuclear cardiology for guiding device therapy in patients with heart failure

Heart failure is a dynamic condition with high morbidity and mortality and its prognosis should be reassessed frequently, particularly in patients for whom critical treatment decisions may depend on the results of prognostication. In patients with heart failure, nuclear cardiology techniques are useful to establish the etiol-ogy and the severity of the disease, while fewer studies have explored the potential capability of nuclear cardi-ology to guide cardiac resynchronization therapy （CRT） and to select patients for implantable cardioverter defbrillators （ICD）. Left ventricular synchrony may be assessed by radionuclide angiography or gated single-photon emission computed tomography myocardial perfusion scintigraphy. These modalities have shown promise as predictors of CRT outcome using phase analysis. Combined assessment of myocardial viability and left ventricular dyssynchrony is feasible using posi-tron emission tomography and could improve conven-tional response prediction criteria for CRT. Preliminary data also exists on integrated positron emission tomog-raphy/computed tomography approach for assessing myocardial viability, identifying the location of biven-tricular pacemaker leads, and obtaining left ventricular functional data, including contractile phase analysis. Fi-nally, cardiac imaging with autonomic radiotracers may be useful in predicting CRT response and for identifying patients at risk for sudden cardiac death, therefore po-tentially offering a way to select patients for both CRT and ICD therapy. Prospective trials where imaging is combined with image-test driven therapy are needed to better defne the role of nuclear cardiology for guiding device therapy in patients with heart failure.

Optimal programming management of ventricular tachycardia storm in ICD patients

Ventricular tachycardia storm （VTS） is defined as a life-threatening syndrome of three or more separate episodes of ventricular tachycardia （VT） leading to implantable cardioverter defibrillator （ICD） therapy within 24 hours. Patients with VTS have poor outcomes and require immediate medical attention. ICD shocks have been shown to be associated with increased mortality in several studies. Optimal programming in minimization of ICD shocks may decrease mortality. Large controlled trials showed that long detection time and high heart rate detection threshold reduced ICD shock burden without an increase in syncope or death. As a fundamental therapy of ICD, anti- tachycardia pacing （ATP） can terminate most slow VT with a low risk of acceleration. For fast VT, burst pacing is more effective and less likely to result in acceleration than ramp pacing. One algorithm of optimal programming management during a VTS is presented in the review.

Results of transvenous lead extraction of coronary sinus leads in patients with cardiac resynchronization therapy

Background The need for transvenous lead extraction procedures of coronary sinus （CS） leads is increasing due to rising numbers of implanted cardiac resynchronization therapy devices during the past decade. Methods From January 2009 to June 2013, 27 CS leads were scheduled for extraction in 27 patients （mean age （63.1±14.6） years）. Indications for lead extraction were infection in 13 and lead dysfunction in 14 cases. Isolated extraction of CS leads was performed in eight, extraction of multiple leads in 19 cases. Among leads with an implant time of 〉12 months （n=19） mean implant duration （MID） was （46.4±15.2） （12-76） months. Groups were formed depending on infectious or non-infectious indications （INF vs. Non-INF）, and the use or non-use of extraction tools （ET1 vs. ET0）. Results Among patients with an implant duration of 〉12 months, complete procedural success was 94.7% and clinical success 100%. Operative mortality was zero. In the INF versus NON-INF groups complete procedural success （100% vs. 91.7%, P=0.43）, mean number of required extraction tools （0.7 （0-2） vs. 0.9 （0-3）, P=0.65） and MID （49.1±15.0 vs. 44.7±15.8, P=0.83） did not differ significantly. Comparing the groups ET1 and ET0 showed no significant differences in complications （n=l vs. n=l, P=-0.81） and MID （47.0±17.5 vs. 45.5±12.6, P=0.71）. Conclusions In specialized centers transvenous lead extraction of coronary sinus leads with a mean implant duration of almost four years can be performed safely and effectively. Neither non-infectious indications nor the use of extraction tools negatively affected the outcome of the procedure.

Home monitoring system improves the detection of ventricular arrhythmia and inappropriate shock

Background The impact of home monitoring system in the early detection of ventricular arrhythmia and inappropriate shock in daily work is not clear. The aim of this study was to investigate the impact of home monitoring system on the early detection of ventricular arrhythmia and inappropriate shock in daily clinical practice. Methods Cases of implantable cardioverter defibrillator （ICD） implantation with or without the home monitoring system from June 2010 to October 2011 at our center were reviewed. Follow-up was scheduled after implantation. Data relating to the home monitoring ICD were retrieved using a remote transmitter system. Data relating to the other devices were obtained during scheduled follow-up or unscheduled visits. Results Our study involved 69 patients （mean age （68.4＋17.6） years, 64.3% males, 26 in the home monitoring group vs. 43 in the non-home monitoring group）. In all, 561 ventricular arrhythmia episodes were detected in 17 patients （39.5%） in the non-home monitoring group： 495 episodes were ventricular tachycardia and 66 episodes were ventricular fibrillation; among these, 476 episodes of ventricular tachycardia and 45 episodes of ventricular fibrillation were appropriately diagnosed （96.1% and 68.2%, respectively）. In the home monitoring group, 389 ventricular arrhythmia episodes were transmitted by the home monitoring system in nine patients （34.6%）： 348 ventricular tachycardia episodes and 41 ventricular fibrillation episodes. Device detection was appropriate in 348 ventricular tachycardia episodes （100.0%） and 36 ventricular fibrillation episodes （87.8%）. The home monitoring group showed a higher appropriate detection rate of ventricular tachycardia （P 〈0.01） and ventricular fibrillation （P=0.02）. The proportion of inappropriate shock was comparable in the two groups （6/11 in the non-home monitoring group vs. 1/7 in the home monitoring group; m=0.08）. Conclusions The home monitoring ICD was able to provide information relating to inappropriate detection and shock earlier than conventional devices. It proved to be a reliable tool and has a strong potential to provide greater reaction time in the case of inappropriate shock.

The role of device therapy in heart failure with reduced ejection fraction(HFrEF) : a narrative review

Heart failure has gained increasing notice due to its high prevalence and mortality rate. The management for heart failure has been emphasized on the role of device therapy. Implantable cardioverter defibrillator(ICD) and cardiac resynchronization therapy(CRT) were given strong recommendation for heart failure with reduced ejection fraction(HFrEF), considering their effectiveness on preventing sudden cardiac death(SCD), improving cardiac function and benefiting survival. In this review, we explained the underlying mechanisms of disease initiation and progression in HFrEF, in order to build the connection between the pathological basis of HFrEF and the rationality of ICD and CRT on terminating ventricular arrhythmia, improving cardiac function, decreasing the rate of adverse clinical outcomes and benefiting survival. In addition, we discussed the high-quality researches with significant values on the discovery of device therapy clinical benefits, and compared the class I recommendations for device therapy in HFr EF, suggested by American Heart Association and European Society of Cardiology.