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.

Concept of defibrillation vector in the management of high defibrillation threshold

We present a case where defibrillation threshold was dangerously elevated to the point that the patient had no safety margin,and his implantable cardioverter-defibrillator generator was discovered to have migrated.Generator migration reduces the distance between the can and the coil,effectively creating a smaller bipolar current and sparing the left ventricle from the current needed for defibrillation.This case underscores the importance of securing the generator in place,as this patient would have been spared multiple shocks and an invasive medical procedure had his generator been better secured.

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.

Construction of Energy-Optimal Smooth Monophasic Defibrillation Pulse Waveforms Using Cardiomyocyte Membrane Model

The goal is to help create smooth energy-optimal monophasic pulse waveforms for defibrillation using the Luo-Rudy cardiomyocyte membrane computer model. The waveforms were described with the help of the piecewise linear function. Each line segment provides a transition from one present level of the transmembrane potential to the next with a minimal energy value. The duration of the last segment was defined as a minimum duration at which an action potential occurs. Monophasic waveforms of segments 3, 10 and 29 were built using different increments of the transmembrane potential. The pulse energy efficiency was evaluated according to their threshold energy ratios in mA2·ms/cm4. There was virtually no difference between the threshold energy ratios of the three waveforms constructed and those of the previously studied energy-optimal half- sine waveform: 241 - 242 and 243 mA2·ms/cm4. The pulse waveform constructed is characterized by a low rise and fall as the duration of the rise is ~1.5 times longer than that of the fall. Conclusion: Energy-optimal smooth monophasic pulse waveforms have the same threshold energy ratio as the optimal half-sine one which was studied before. The latter is equivalent to the first phase of biphasic quasisinusoidal Gurvich-Venin pulse which has been used in Russia since 1972. Thus, the use of the Luo-Rudy cardiomyocyte membrane model appears to offer no possibilities for a substantial increase in the energy efficiency (threshold energy ratio reduction) of the classical monophasic defibrillation pulse waveforms.

Energy Level and Success of Internal Defibrillation for Shockable Rhythm during Cardiopulmonary Bypass in Cardiac Surgery:A Retrospective Study

Internal defibrillation is commonly indicated for shockable rhythm following cross-clamp removal in cardiac surgery.Low energy decreases the success rate of defibrillation but high energy can cause myocardial damage.This study aimed to determine the success rate of internal defibrillation for shockable arrhythmias after cardiac surgery.Retrospective data of 1,424 patients who developed shockable rhythms(ventricular fibrillation or ventricular tachycardia),and required internal defibrillation after aortic cross-clamp removal during cardiac surgery,without deep hypothermic circulatory arrest technique,from August 2015 to July 2017,were reviewed.The overall success rate of internal defibrillation in the first attempt of defibrillation was 61.5%.The success rate of the energy levels at 30,10,and 7 Jules were 66.7,64.9,and 61.5%,respectively.The success rate was higher in patients who had a better ejection fraction than those who failed after defibrillation.This was significantly associated with higher pH,higher bicarbonate,lower serum calcium,and lower total cardioplegic volume during cardiopulmonary bypass(CPB).Redo-valve surgery,valvular surgery,and combined coronary artery bypass graft with valvular surgery had a non-significantly lower success rate(p-value=0.989).Incidence of failure for defibrillate patients in redo-valvular surgery,combined coronary artery bypass graft with valve surgery,adult congenital heart defect,and valvular surgery;requiring four or five shocks was non-significantly increased.Recurrent rate of ventricular fibrillation/ventricular tachycardia was 13.5%.The success rate of internal defibrillation was not related to the dose of energy used after being weaned off CPB.

Intrahospital Dissemination of Automatic External Defibrillators Decrease Time to Defibrillation of In-Hospital Cardiac Arrests

Background: Survival rates for in-hospital cardiac (IHCA) arrest are low. Early defibrillation is vital and international guidelines, which requests defibrillation within three minutes. Can dissemination of automatic external defibrillators (AED) at hospital wards shorten time to defibrillation compared to standard care, calling for medical emergency team (MET)? Material & Methods: Forty-eight (48) units at S?dersjukhuset, Sweden, were included in the study. They were divided into the intervention group (24 units equipped with AEDs) and the standard care group (24 units with no AEDs). Intervention group staff were trained in CPR to use AEDs and standard care group staff were trained in just CPR. Data were gathered from patient records, AEDs and the Swedish National Registry of Cardiopulmonary Resuscitation (NRCR). Results: 126 IHCA patients were included, 47 in the standard care group, 79 in the intervention group. AEDs in the intervention group were connected to a defibrillator and it was ready to shock before arrival of MET in 83.5% of all cases. AEDs were ready to be used on average 96 seconds (14-427 s) before arrival of MET. Seven (15%) patients were defibrillated in the control group and Twenty (25%) in the intervention group. Defibrillation within three minutes occurred in 67% in the intervention group (11/17), compared with none (0/7) in the control group (p = 0.02). Conclusion: A systematic implementation of AEDs in hospital wards decrease time to defibrillation compared to a standard MET response system. Larger studies are needed to evaluate the impact on the outcome.

A Review of Compression, Ventilation, Defibrillation, Drug Treatment, and Targeted Temperature Management in Cardiopulmonary Resuscitation

Objective：Important studies of cardiopulmonary resuscitation （CPR） techniques influence the development of new guidelines.We systematically reviewed the efficacy of some important studies of CPR.Data Sources：The data analyzed in this review are mainly from articles included in PubMed and EMBAS E,published from 1964 to 2014.Study Selection：Original articles and critical reviews about CPR techniques were selected for review.Results：The survival rate after out-of-hospital cardiac arrest （OHCA） is improving.This improvement is associated with the performance of uninterrupted chest compressions and simple airway management procedures during bystander CPR.Real-time feedback devices can be used to improve the quality of CPR.The recommended dose,timing,and indications for adrenaline （epinephrine） use may change.The appropriate target temperature for targeted temperature management is still unclear.Conclusions：New studies over the past 5 years have evaluated various aspects of CPR in OHCA.Some of these studies were high-quality randomized controlled trials,which may help to improve the scientific understanding of resuscitation techniques and result in changes to CPR guidelines.

Ibutilide decreases defibrillation threshold by the reduction of activation pattern complexity during ventricular fibrillation in canine hearts

Background Ibutilide has been commonly used for pharmacologic cardioversion of atrial fibrillation and flutter in clinical settings. The objective of this study was to investigate the effects of ibutilide on the defibrillation threshold （DFT）, restitution properties, dispersion of refractoriness and activation patterns during ventricular fibrillation （VF）. Methods Ibutilide was administrated intravenously in six open-chest beagles. Before and after the drug administration, 20-second episodes of VF were electrically induced and recorded with a 10×10 unipolar electrode plaque sutured on the lateral epicardium of the left ventricle. DFT and VF activation patterns, including type of epicardial activation maps, VF cycle length （VF-CL）, conduction velocity, wavelength （WL） and reentry incidence, were measured. Restitution properties and dispersion of refractoriness were estimated from activation recovery intervals （ARI） during pacing. Results Compared to baseline, ibutilide markedly decreased the DFT by 31% （（491±14） V vs. （337±59） V, P 〈0.01）. The drug significantly reduced the maximal slope of the restitution curve （1.34±0.08 vs. 0.76±0.06, P 〈0.01） and its epicardial dispersion （0.36±0.09 vs. 0.21±0.06, coefficient of variation, P=0.03）. The dispersion of refractoriness was enhanced at the pacing cycle length of 300 ms to 160 ms by ibutilide. The drug significantly increased the VF-CL （（96±19） ms vs. （112±20） ms, P 〈0.01） and the WL （（41±9） mm vs. （52±14） mm, P=0.02） during VF, and reduced the reentry incidence by 25% （0.08±0.02 vs. 0.06±0.02, P 〈0.01）. In the epicardial activation maps, ibutilide significantly reduced the percentage of more complex activation maps during VF. Conclusions Intravenous ibutilide significantly decreased the DFT. It might be due to reduction of activation pattern complexity during VF.

Antiarrhythmic drugs and ventricular defibrillation energy requirements

Purpose To understand the potential interaction between antiarrhythmic therapy and the implantable cardioverter defibrillator (ICD) in patients who receive pharmacologic therapy as an adjunct to ICD therapy Data sources MEDLINE searching was employed and the information was indexed from approximately 3600 journals published world wide from 1966 to 1998 Study selection and data extraction Data were collected from 66 of approximately 455 originally identified articles and abstracts using explicit methodological criteria Results The ICD therapy has been widely used for therapy of life threatening ventricular arrhythmias (VT/VF) and prevention of recurrence of sudden cardiac death Studies reported that 40%-70% or 10%-40% of ICD patients required concomitant antiarrhythmic medication to reduce the frequency of sustained arrhythmic episodes and to minimize the frequency of device discharges Most studies on antiarrhythmic drug ICD interactions have been performed in experimental animals Antiarrhythmic drugs can influence the effectiveness of ICD to terminate arrhythmias through their effects on defibrillation threshold (DFT) Studies have demonstrated a rise in DFTs with class Ib agent lidocaine and class Ic agents encainide and flecainide Class Ia agents, as well as amiodarone, bretylium and propafenone may have more variable effects on DFT probably because of the difference between acute and chronic drug dosing, dose related changes, active metabolites, and reproducibility in determining DFT Class Ⅲ agents, with the exception of amiodarone, consistently decrease DFT These drugs can be used as front line agents in ICD patients Conclusions Antiarrhythmic drugs can increase, decrease, or have no effect on DFT Class Ⅲ agents except amiodarone can be safely administered in conjunction with ICD patients as long as the interaction between these therapeutic modalities is appreciated

Effect of a low-cost instruction card for automated external defibrillator operation in lay rescuers: a randomized simulation study

BACKGROUND:To evaluate whether a simplified self-instruction card can help potential rescue providers use automated external defibrillators(AEDs)more accurately and quickly.METHODS:From June 1,2018,to November 30,2019,a prospective longitudinal randomized controlled simulation study was conducted among 165 laypeople(18–65 years old)without prior AED training.A self-instruction card was designed to illuminate key AED operation procedures.Subjects were randomly divided into the card(n=83)and control(n=82)groups with age stratification.They were then individually evaluated in the same simulated scenario to use AED with(card group)or without the self-instruction card(control group)at baseline,posttraining,and at the 3-month follow-up.RESULTS:At baseline,the card group reached a significantly higher proportion of successful defibrillation(31.1%vs.15.9%,P=0.03),fully baring the chest(88.9%vs.63.4%,P<0.001),correct electrode placement(32.5%vs.17.1%,P=0.03),and resuming cardiopulmonary resuscitation(CPR)(72.3%vs.9.8%,P<0.001).At post-training and follow-up,there were no significant differences in key behaviors,except for resuming CPR.Time to shock and time to resume CPR were shorter in the card group,while time to power-on AED was not different in each phase of tests.In the 55–65 years group,the card group achieved more skill improvements over the control group compared to the other age groups.CONCLUSION:The self-instruction card could serve as a direction for first-time AED users and as a reminder for trained subjects.This could be a practical,cost-effective way to improve the AED skills of potential rescue providers among different age groups,including seniors.

Mismatch between Sites of Incidence of Out-of-Hospital Cardiac Arrest and Locations of Installed Automated External Defibrillator in the Tokyo Metropolitan Area

Background: Since 2004, the number of installed Automated External Defibrillator (AED) has been increased in Japan annually, the cumulative number of sold AED more than 600,000 units by 2016. Despite there have been about 130,000 out of hospital cardiac arrest annually, there have only 1302 cases delivered defibrillation by bystanders at the scene. Therefore, we investigate that number of AED installation and usage rate for Out of Hospital Cardiac Arrest (OHCA) patients. Methods: Retrospective metropolitan wide cohort study. Subject: Total 13,364 OHCA patients in the Tokyo Metropolitan area from Jan. 1 through Dec. 31 in 2012 were eligible for theses analyses. Also, OHCA occurrence place and AED usage rate were studied. Results: 82.8% of OHCA occurred at residences, 10% at outdoors, 6.4% at indoors, only 0.7% at schools. In the other hand, highest bystander’s CPR rates were found in sports facilities and schools (71.4%). The installation rate of AEDs in residences was 9.6%, instead of highest incidence for OHCA patients, school and sports institute made up 21.4% of AED installations, but only 1.0% of the incidences of cardiac arrest. We found that there is a mismatch between incidence sites of cardiac arrest and locations of installed AED. Discussion: It is essential to increase the number of AED installations. Furthermore, it is desirable to install AEDs in locations where cardiac arrest is liable to occur following guidelines for the proper placement of AEDs, and important to further spread BLS education among the general citizens.

Advances in clinical studies of cardiopulmonary resuscitation

BACKGROUND: The survival rate of patients after cardiac arrest(CA) remains lower since 2010 International Consensus on Cardiopulmonary Resuscitation(CPR) and Emergency Cardiovascular Care(ECC) was published. In clinical trials, the methods and techniques for CPR have been overly described. This article gives an overview of the progress in methods and techniques for CPR in the past years.DATA SOURCES: Original articles about cardiac arrest and CPR from MEDLINE(PubM ed) and relevant journals were searched, and most of them were clinical randomized controlled trials(RCTs).RESULTS: Forty-two articles on methods and techniques of CPR were reviewed, including chest compression and conventional CPR, chest compression depth and speed, defibrillation strategies and priority, mechanical and manual chest compression, advanced airway management, impedance threshold device(ITD) and active compression-decompression(ACD) CPR, epinephrine use, and therapeutic hypothermia. The results of studies and related issues described in the international guidelines had been testifi ed.CONCLUSIONS: Although large multicenter studies on CPR are still difficult to carry out, progress has been made in the past 4 years in the methods and techniques of CPR. The results of this review provide evidences for updating the 2015 international guidelines.

Igor V. Venin Founder of Biphasic Waveform Defibrillators

Igor V. Venin since 1966 and up till now has been an outstanding engineer of the Soviet Union and Ukraine, who has dedicated all his life to defibrillators development. Under his guidance 16 models of DC defibrillators with different waveforms, including the world’s first defibrillator with biphasic waveform (1971) have been developed and put into commercial production.

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.

Cardiac Arrest Cases and Automated External Defibrillator Use in Railroad Stations in Tokyo

Objective: Nationwide dissemination of public-access defibrillation (PAD) contributed to an increase of survival rate in Japan. We analysed cardiac arrests (CAs) that occurred in railroad stations in Tokyo to evaluate PAD in the metropolis. Methods: We collected Utstein data from the Tokyo Fire Department (TFD) and analysed CA cases that occurred in stations. In total, 245 non-traumatic CAs from January 1, 2007 to March 31, 2008 were analysed;CAs in children under 8 years were excluded. Results: The rates of pre-hospital return of spontaneous circulation (ROSC) were 41 out of 145 witnessed CA patients (28.3%) and 12 ROSC out of 100 unwitnessed CA patients (12%). Of 245 CA cases, bystander cardiopulmonary resuscitation (CPR) performed in 156 (63.7%), automated external defibrillator (AED) used in 117 (47.8%) and shock delivered in 65 (26.5%). Rates of ROSC were 31.6% (37/117) with AED use significantly higher than those of 12.5% (16/128) without AED use (P < 0.001). Most CAs occurred on platforms;the use of AEDs on platforms increased from 18/31 (58.1%) in 2007 to 32/43 (74.4%) in 2008 and ROSC rates increased from 8 (25.8%) to 14 (32.6%), respectively. On train CAs: ROSC cases were very few, 1 case each year (8.3%;7.7%) while the use of AED increased from 8/12 (66.7%) in 2007 to 10/13 (76.9%) in 2008. Conclusion: Bystander CPR and the use of AED at railroad stations improved ROSC for out-of-hospital cardiac arrest (OHCA) patients. AED location and strategies for dealing with CAs on trains should be re-evaluated.

AED,LifeVest Defi brillator or Hybrid Approach

Early defibrillation is critical to survival in any patient with a cardiac arrest.Electrophysiologists who implant ICDs(implantable cardioverter defi-brillators)test them by fi brillating the patient followed by immediate defibrillation.This emphasizes the point that early defibrillation results in survival of these patients;CPR is done only if there is a delay in obtaining the defi brillator or if the ICD is not working.

Study of the Impact of Rectangular Current Pulses on the Ten Tusscher-Panfilov Model of Human Ventricular Myocyte

The behavior of the 2006 ten Tusscher-Panfilov model of human ventricular myocytes under the impact of periodic excitation impulses was studied in the BeatBox simulation environment. The cardiomyocyte model has a limited susceptibility to an forced higher frequency excitation rhythm. A high-frequency excitation rhythm can be forced by gradually increasing the frequency of excitation impulses. The mechanism of defibrillation pulse impact consists of presumably prolonging the refractoriness of cardiomyocytes which undermines their susceptibility for a long time to a forced high-frequency rhythm of fibrillation, as a result for which they hinder the propagation of a fibrillation wave. This is the only mechanism of defibrillation that was identified during the simulation. The threshold energy of a depolarizing defibrillation pulse prolonging the refractoriness of the cardio-myocyte varies depending on a delay relative to the excitation impulse (the excitation cycle phase) in a wide range (the maximum value exceeds the minimum by several thousand times). The results show differences in the mechanisms of impact on a cardiomyocyte between an excitation impulse and a monophasic defibrillation pulse.

Nursing Care of Patients With Transcatheter Closure of Atrial Septal Defect via Femoral Vein

Objective:To explore the operative nursing coordination method for the treatment of congenital atrial septal defect(ASD)by transcatheter closure of atrial septal defect via femoral vein.It provides useful experience for the treatment of congenital heart disease.Methods a total of 12 patients undergoing minimally invasive atrial septal defect closure via femoral vein from January 2017 to November 2017 in our department of cardiac surgery were selected as the subjects.All patients received transesophageal ultrasound guided ASD occlusion by femoral vein.The operation and nursing contents include preoperative care,the cooperation of the itinerant nurses,the coordination of the instrument nurses and the postoperative nursing.Results the operation of 12 patients in this group was successful.The diameter of the occluder was 17.1+4.5 mm during the operation.The time of tracheal intubation was 2.4+0.7 h,from the femoral vein to the sheath tube time was 38.7+9.4 min,the occupancy of ICU was 12.5+2.6 h after the operation.The average time of hospitalization was 4.5+1.8 D.There were 2 cases of shunt 1mm immediately after operation.After 24h reexamination,the shunt disappeared,the heart murmur disappeared in the rest of the patients.No residual shunt and other complications occurred.

Arrhythmogenic ventricular cardiomyopathy:A paradigm shift from right to biventricular disease

Arrhythmogenic ventricular cardiomyopathy(AVC) isgenerally referred to as arrhythmogenic right ventricu-lar(RV) cardiomyopathy/dysplasia and constitutesan inherited cardiomyopathy.Affected patients maysuccumb to sudden cardiac death(SCD),ventriculartachyarrhythmias(VTA) and heart failure.Geneticstudies have identified causative mutations in genesencoding proteins of the intercalated disk that lead toreduced myocardial electro-mechanical stability.Theterm arrhythmogenic RV cardiomyopathy is somewhatmisleading as biventricular involvement or isolated leftventricular(LV) involvement may be present and thus abroader term such as AVC should be preferred.The di-agnosis is established on a point score basis accordingto the revised 2010 task force criteria utilizing imagingmodalities,demonstrating fibrous replacement throughbiopsy,electrocardiographic abnormalities,ventricu-lar arrhythmias and a positive family history includingidentification of genetic mutations.Although severarisk factors for SCD such as previous cardiac arrest,syncope,documented VTA,severe RV/LV dysfunctionand young age at manifestation have been identified,risk stratification still needs improvement,especially inasymptomatic family members.Particularly,the roleof genetic testing and environmental factors has to befurther elucidated.Therapeutic interventions include re-striction from physical exercise,beta-blockers,sotalol,amiodarone,implantable cardioverter-defibrillators andcatheter ablation.Life-long follow-up is warranted insymptomatic patients,but also asymptomatic carriersof pathogenic mutations.

Small bowel capsule endoscopy in patients with cardiac pacemakers and implantable cardioverter defibrillators:Outcome analysis using telemetry review

AIM:To determine if there were any interactions between cardiac devices and small bowel capsules secondary to electromagnetic interference (EMI) in patients who have undergone small bowel capsule endoscopy (SBCE).METHODS:Authors conducted a chart review of 20 patients with a cardiac pacemaker (CP) or implantable cardioverter defibrillator (ICD) who underwent continuous electrocardiographic monitoring during their SBCE from 2003-2008.authors searched for unexplained electrocardiogram (ECG) findings,changes in CP andICD set parameters,any abnormality in transmitted capsule data,and adverse clinical events.RESULTS:There were no adverse events or hemodynamically significant arrhythmias reported.CP and ICD set parameters were preserved.The majority of ECG abnormalities were also found in pre-or post-SBCE ECG tracings and the CP behavior during arrhythmias appeared appropriate.Two patients seemed to have episodes of undersensing by the CP.However,similar findings were documented in ECGs taken outside the time frame of the SBCE.One patient was observed to have a low signal encountered from the capsule resulting in lack of localization,but no images were lost.CONCLUSION:Capsule-induced EMI remains a possibility but is unlikely to be clinically important.CPinduced interference of SBCE is also possible,but is infrequent and does not result in loss of images transmitted by the capsule.