Wireless Power Supply Based on MNG-MNZ Metamaterial for Cardiac Pacemakers

To solve the low power transfer efficiency and magnetic field leakage problems of cardiac pacemaker wireless powering, we proposed a wireless power supply system suitable for implanted cardiac pacemaker based on mu-negative(MNG) and mu-nearzero(MNZ) metamaterials. First, a hybrid metamaterial consisted of central MNG unit for magnetic field concentration and surrounding MNZ units for magnetic leakage shielding was established by theoretical calculation. Afterwards, the magnetic field distribution of wireless power supply system with MNG-MNZ metamaterial slab was acquired via finite element simulation and verified to be better than the distribution with conventional MNG slab deployed. Finally, an experimental platform of wireless power supply system was established with which power transfer experiment and system temperature rise experiment were conducted.Simulation and experimental results showed that the power transfer efficiency was improved from 44.44%,19.42%, 8.63% and 6.19% to 55.77%, 62.39%, 20.81%and 14.52% at 9.6 mm, 20 mm, 30 mm and 50 mm,respectively. The maximum SAR acquired by SAR simulation under human body environment was-7.14 dbm and maximum reduction of the magnetic field strength around the receiving coil was 2.82 A/m. The maximum temperature rise during 30min charging test was 3.85℃,and the safety requirements of human bodies were met.

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.

Leadless pacemakers： a contemporary review

1 Introduction Over one million cardiac pacemakers are implanted every year worldwide,[11 of which approximately 200,000 are implanted in the United States alone.121 Combined with an aging population and increasing pacing indications, these numbers are expected to grow. Since the first pacemaker implantation in 1950s, cardiac pacemaker technology has rapidly advanced. Reduction in generator size, increased battery longevity, quality of pacemaker leads, algorithmic and rate responsive programming-all have revolutionized and transformed the implantation and management of transvenous cardiac pacemaker （TV-PPM）.

Use of Rats Mesenchymal Stem Cells Modified with mHCN2 Gene to Create Biologic Pacemakers

The possibility of rats mesenchymal stem cells (MSCs) modified with murine hyperpolarization-activated cyclic nucleotide-gated 2 (mHCN2) gene as biological pacemakers in vitro was studied. The cultured MSCs were transfected with pIRES2-EGFP plasmid carrying enhanced green fluorescent protein (EGFP) gene and mHCN2 gene. The identification using restriction enzyme and sequencing indicated that the mHCN2 gene was inserted to the pIRES2-EGFP. Green fluorescence could be seen in MSCs after transfection for 24–48 h. The expression of mHCN2 mRNA and protein in the transfected cells was detected by RT-PCR and Western blot, and the quantity of mHCN2 mRNA and protein expression in transfected MSCs was 5.31 times and 7.55 times higher than that of the non-transfected MSCs respectively (P<0.05, P<0.05). IHCN2 was recorded by whole-cell patch clamp method. The effect of Cs+, a specific blocker of pacemaker current, was measured after perfusion by patch clamp. The results of inward current indicated that there was no inward current recording in non-transfected MSCs and a large voltage-dependent inward and Cs+-sensitive current activated on hyperpolarizations presented in the transfected MSCs. IHCN2 was fully activated around–140 mV with an activation threshold of –60 mV. The midpoint (V50) was –95.1±0.9 mV (n=9). The study demonstrates that mHCN2 mRNA and protein can be expressed and the currents of HCN2 channels can be detected in genetically modified MSCs. The gene-modified MSCs present a novel method for pacemaker genes into the heart or other electrical syncytia.

A Meta-analysis of Major Complications between Traditional Pacemakers and Leadless Pacemakers

Objectives:We aim to compare the major complications between leadless pacemakers and traditional pacemakers.Background:Leadless pacemakers,which are increasingly used in clinical practice,have several advantages compared with traditional pacemakers in avoiding pocket-and lead-related complications.However,the clinical effect of leadless pacemakers remains controversial.Methods:PubMed,Embase,the Cochrane Central Register of Controlled Trials(CENTRAL),the CNKI database,and the Wanfang database were searched from July 2013 to December 2019.Studies comparing leadless pacemakers and traditional pacemakers were included.The primary end point was major complications.The secondary end points were cardiac perforation/pericardial effusion,device revision or extraction,loss of device function,and death.Results:Six studies fulfi lled the inclusion criteria.Only four of the six studies reported data on major complications.Leadless pacemakers were associated with a lower incidence of major complications(risk ratio 0.33,95%confi dence interval 0.25–0.44,P<0.00001,I²=49%).We extracted data on cardiac perforation/pericardial effusion,device revision or extraction,loss of device function,and death from six studies.Our meta-analysis showed that leadless pacemakers have a higher risk of cardiac perforation or pericardial effusion(risk ratio 4.28,95%confi dence interval 1.66–11.08,P=0.003,I²=0%).No statistically signifi cant differences were found for mortality,device revision or extraction,and loss of device function.Conclusion:Compared with traditional pacemakers,leadless pacemakers have a signifi cantly decreased risk of major complications,but have a higher risk of cardiac perforation or pericardial effusion.

Interference between pacemakers/implantable cardioverter defibrillators and video capsule endoscopy

Our Letter to the Editor, related to the article "Small bowel capsule endoscopy in patients with cardiac pacemakers and implantable cardioverter defibrillators: Outcome analysis using telemetry" by Cuschieri et al , comments on some small errors, that slipped into the authors discussions. The given informations concerning the pacemakerand implantable cardioverter defibrillators modes were inaccurate and differ between the text and the table. Moreover, as 8 of 20 patient's pacemakers were programmed to VOO or DOO ("interference mode") and one patient was not monitored by telemetry during capsule endoscopy, 9 of 20 patients (45%) lack the informations of possible interference between capsule endoscopy their implanted device. Another objection refers to the interpretation of an electrocardiogram (figure 1, trace B) presented: in contrast to the author's opinion the marked spike should be interpreted as an artefact and not as "undersensing of a fibrillatory wave". Finally, three comments to cited reviews were not complete respectively not quoted correctly.

An Artificial Heart System for Testing and Evaluation of Cardiac Pacemakers

The usability assessment of a pacemaker is a complex task where the dedicated programmer for testing programmed algorithms is necessary.This paper provides the outcomes of development and complex testing of the artificial cardiac system to evaluate the pacemaker’s functionality.In this work,we used the modular laboratory platform ELVIS II and created graphical user interface in LabVIEW programming environment.The electrical model of the heart allows signals generation(right atrium,right ventricle)and the monitoring of the stimulation pulses.The LabVIEW user interface allows to set the parameters of the generated signals and the simulation of the cardiac rhythm disorders as well as the monitoring and visualization of the pacemaker behavior in real-time.The results demonstrate the capability of proposed system to evaluate the paced and sensed pulses.The proposed solution allows the scientists to test the behavior of any cardiac pacemaker for its pre-programmed settings and pacing mode.In addition,the proposed system can simulate various disorders and test cardiac pacemakers in different working modes.

Epicardial Versus Endocardial Pacemakers in the Pediatric Population:A Comparative Inquiry

Background:Most children in need of cardiac pacemakers remain dependent on the function of the permanent from childhood to adulthood.We sought to evaluate and compare the function between epicardial and endocardial pacemakers in pediatric groups with different conditions.Methods:Between 2012 and 2018,this single-canter study evaluated 44 pediatric patients with indications for epicardial or endocardial pacemakers.Results:The 2 groups,at a median age of 5(0.1–16)years,were compared concerning the characteristics of the leads used(n=80:bipolar,unipolar,steroid-eluting,and non–steroid-eluting),survival data,and complications.The reason for pacemaker implantation was congenital complete heart block in 11(25%)cases and postoperative heart block in 33(75%)cases.The commonest congenital heart disease accompanied by postoperative block was the ventricular septal defect.In the endocardial lead group,the mean ventricular pacing threshold immediately after the implantation and during the follow-up was less than that in the epicardial lead group(0.75 vs.0.81 V;P=0.01 and 0.8 vs.2.4 V;P=0.001).During the follow-up,the mean battery longevity was better in the endocardial group(last visit:6.7 endocardial vs.3.3 years epicardial).Lead failure was commoner in the epicardial pacemaker,and chronic high-pacing threshold pattern was seen in 14 patients in this group.After 3 years,freedom from lead failure was 94%and 63%in the endocardial and epicardial leads.Conclusions:Pacemakers with endocardial bipolar steroid-eluting leads showed better lead characteristics regarding survival and battery longevity than epicardial pacemakers without these lead characteristics.An appropriate pacemaker type should be selected based on the patient’s condition.

A portable,economic drainage device to prevent pocket hematoma of pacemakers

Objective:To make up a portable,economic drainage device to prevent the development of pocket hematoma and avoid the additional therapies of pocket hematoma.Methods:Between 2003 and 2006,a total of 265 devices were implanted at our institution.The 89 high-risk patients were determined by the predictors of hematoma occurrence(marasmatic elder,inevitable oral antiplatelet/anticoagulation therapy,venous pressure increased by other comorbidity,the deficiency of the clotting mechanism for hepatic diseases,or incognizable severe intraoperative bleeding),and other 186 patients were included in non-high-risk group.The 89 high-risk patients were randomized into treatment and control subgroups by sortition.Surgical procedures differed only by the application of the portable,economic drainage device prior to wound closure in treatment subgroup.Results:The incidence of pocket hematoma was 4.3% in treatment subgroup,18.6% in control subgroup and 2.7% in non-high-risk group,leading to 2,6 and 3 patients' prolonged hospitalization,respectively.The additional cost due to pocket hematoma was lower(1.5 times) in the treatment group compared to the control group.There wasn't antidromic infection and delayed cure of the skin incision with the use of our drainage device within 6 months.Conclusion:Our portable drainage device was made up easily and quickly.It could decrease the total cost of hospitalization,did not increase the other adverse events and seemed to be suitable for such patients with a tendency to develop pocket hematoma undergoing the implantation of pectoral pacemakers,implantable cardioverter defibrillator,or cardiac resynchronization therapy.

Precision of a Parabolic Optimum Calculated from Noisy Biological Data, and Implications for Quantitative Optimization of Biventricular Pacemakers (Cardiac Resynchronization Therapy)

In patients with heart failure and disordered intracardiac conduction of activation, doctors implant a biven- tricular pacemaker (“cardiac resynchronization therapy”, CRT) to allow adjustment of the relative timings of activation of parts of the heart. The process of selecting the pacemaker timings that maximize cardiac function is called “optimization”. Although optimization—more than any other clinical assessment—needs to be precise, it is not yet conventional to report the standard error of the optimum alongside its value in clinical practice, nor even in research, because no method is available to calculate precision from one optimization dataset. Moreover, as long as the determinants of precision remain unknown, they will remain unconsidered, preventing candidate haemodynamic variables from being screened for suitability for use in optimization. This manuscript derives algebraically a clinically-applicable method to calculate the precision of the optimum value of x arising from fitting noisy biological measurements of y (such as blood flow or pressure) obtained at a series of known values of x (such as atrioventricular or interventricular delay) to a quadratic curve. A formula for uncertainty in the optimum value of x is obtained, in terms of the amount of scatter (irreproducibility) of y, the intensity of its curvature with respect to x, the width of the range and number of values of x tested, the number of replicate measurements made at each value of x, and the position of the optimum within the tested range. The ratio of scatter to curvature is found to be the overwhelming practical determinant of precision of the optimum. The new formulae have three uses. First, they are a basic science for anyone desiring time-efficient, reliable optimization protocols. Second, asking for the precision of every reported optimum may expose optimization methods whose precision is unacceptable. Third, evaluating precision quantitatively will help clinicians decide whether an apparent change in optimum between successive visits is real and not just noise.

Management of Cardiac Pacemakers in a Pregnant Patient

Introduction: Despite the increasing use of permanent cardiac pacemakers in a younger patient population, there are little data related to pregnancy. We present our experience in managing a pregnant patient with a pre-existing pacemaker and review the existing literature to establish management guidelines. Case: A 27-year-old G1 P0 presented for prenatal care in the first trimester of pregnancy. She had a past medical history of bradycardia, hypotension and syncope that required dual chamber cardiac pacemaker placement 6 years earlier, and one episode of left upper extremity venous thrombosis related to replacement of the pacemaker wire 4 years earlier. In the early second trimester, the patient began experiencing light-headedness and breathlessness with exertion. The rate settings of the pacemaker were increased with resolution of the patient’s symptoms. The patient underwent primary cesarean section at 39 weeks gestation with delivery of a healthy term infant. Preoperative anesthesia consultation was obtained. The postoperative course was uneventful. Pre-pregnancy pacemaker settings were re-established after the postpartum period. Discussion: The current literature on managing pregnant patients with pre-existing pacemakers is quite limited. Such patients require a multidisciplinary approach to care. Normal physiologic changes in pregnancy may necessitate rate adjustments. Other than routine thromboprophylaxis, no other anticoagulation is needed. Route of delivery is generally based on obstetric indications. During surgery consider using bipolar electrocautery in place of unipolar electrocautery, to reduce electromagnetic interference. Also, the placement of the grounding pad should be as far away from the pacemaker as possible. It should be anticipated that the patient will return to her baseline cardiac status postpartum and therefore pacemaker settings can be adjusted accordingly.

Inhibition of the Oversensing of Cardiac Pacemakers in Chest CT

Objectives: The purpose of this study is to identify how to manage oversensing of pacemakers in chest CT. Methods: Four different models of pacemakers were examined to select the pacemaker generating oversensing. To the pacemaker with oversensing, intermittent switching X-ray was exposed using ECG-gated CT helical scan system at prospective CTA mode. IVY Model was used to synchronize the ECG. Only during in the alert period that is non-refractory and sensing is available, intermittent switching X-ray (300 msec/sec) was exposed in chest CT. For comparison, the same intermittent switching X-ray (300 msec/sec) was exposed in the refractory period when sensing was not available. Results: Oversensing was detected only in one of the four pacemakers tested. In this pacemaker, oversensing was generated by exposure of the intermittent switching X-ray in the alert (non-refractory) period, but oversensing was not observed in the refractory period. Conclusion: A pacemaker has alert and refractory periods. Oversensing of a pacemaker was found to be inhibited by selective ECG-synchronized exposure in the refractory period. Since all pacemakers have the refractory period, the results of this study can be widely applied to the patients with pacemakers in chest CT, and their chest CT can be operated safely.

Selective his bundle pacing eliminates crochetage sign:A case report

BACKGROUND Crochetage sign is a specific electrocardiographic manifestation of ostium secundum atrial septal defects(ASDs),which is associated with the severity of the left-to-right shunt.Herein,we reported a case of selective his bundle pacing(SHBP)that eliminated crochetage sign in a patient with ostium secundum ASD.CASE SUMMARY A 77-year-old man was admitted with a 2-year history of chest tightness and shortness of breath.Transthoracic echocardiography revealed an ostium secundum ASD.Twelve-lead electrocardiogram revealed atrial fibrillation with a prolonged relative risk interval,incomplete right bundle branch block,and crochetage sign.The patient was diagnosed with an ostium secundum ASD,atrial fibrillation with a second-degree atrioventricular block,and heart failure.The patient was treated with selective his bundle pacemaker implantation.After the procedure,crochetage sign disappeared during his bundle pacing on the electrocardiogram.CONCLUSION S-HBP eliminated crochetage sign on electrocardiogram.Crochetage sign may be a manifestation of a conduction system disorder.

Current knowledge for the risk factors of early permanent pacemaker implantation following transcatheter aortic valve replacement and what is next for the primary prevention?

In this editorial,we comprehensively summarized the preoperative risk factors of early permanent pacemaker implantation after transcatheter aortic valve replacement(TAVR)among patients with severe aortic stenosis from several renowned clinical studies and focused on the primary prevention of managing the modifiable factors,e.g.,paroxysmal atrial fibrillation before the TAVR.

Impact of single chamber and dual chamber permanent pacemaker implantation on left ventricular function:An observational study

BACKGROUND Permanent pacemaker implantation has the potential to impact left ventricular(LV)function and hence quality of life(QoL)in the long term.AIM To assess the effect of single-and dual-chamber pacing on LV function and QoL.METHODS This study included 56 patients who underwent permanent pacing:Dual pacing,dual sensing,dual responsive and rate responsive(DDDR)for the initial 3 months,ventricular sensing,inhibited response and rate responsive(VVIR)for the next 3 months,and DDDR mode for the last 3 months.Throughout the study period,various echocardiographic parameters,functional status,and QoL were measured to assess the impact of pacing on LV function compared with baseline and at every 3 months interval.RESULTS A significant change appeared in cardiac function after VVIR pacing which was in diastolic properties of LV as shown by increase in isovolumic relaxation time from(85.28±9.54 ms)to(89.53±9.65 ms).At the 3-,6-,and 9-month follow-up,reduction in LV ejection fraction was observed to be 62.71±4.66%,61.07±4.41%,and 58.48±3.89%,respectively.An increase in the QoL scores was noted at every follow-up visit.CONCLUSION An apparent depressant effect on LV function due to right ventricular pacing,with a higher incidence of adverse outcomes in the VVIR mode.In addition,an upsurge in QoL scores for the study population was noted,which indicates improvement in the QoL of patients post-pacing,irrespective of the mode.Generally,the DDDR mode is a highly preferable pacing mode.

Dual-chamber pacing confers better myocardial performance and improves clinical outcomes compared to single-chamber pacing

The deleterious effects of long term right ventricular pacing are increasingly being recognized today.Current clinical practice favors the implantation of dual-chamber permanent pacemaker which maintains atrioventricular synchrony and is associated with better quality of life.However,despite the popular belief and common sense surrounding the superiority of dual-chamber pacing over single chamber pacing,the same has never been conclusively verified in clinical trials.Some observational evidence however,does exists which supports the improved cardiac hemodynamics,lower the rate of atrial fibrillation,heart failure and stroke in dual-chamber pacing compared to single-chamber pacing.In the index study by Haque et al,right ventricular pacing,particularly in ventricular paced,ven-tricular sensed,inhibited response and rate responsive pacemaker adversely im-pacted the left ventricular functions over 9-months compared to dual pacing,dual sensing,dual responsive and rate responsive pacemaker.Although there are key limitations of this study,these findings does support a growing body of evidence reinstating the superiority of dual chamber pacing compared to single chamber pacing.

Risk of permanent pacemaker implantation following transcatheter aortic valve replacement:Which factors are most relevant?

Transcatheter aortic valve replacement(TAVR)has emerged as a formidable treatment option for severe symptomatic aortic stenosis ahead of surgical aortic valve replacement.The encouraging results from large randomized controlled trials has resulted in an exponential rise in the use of TAVR even in the low-risk patients.However,this is not without challenges.Need for permanent pacemaker(PPM)post-TAVR remains the most frequent and clinically relevant challenge.Naturally,identifying risk factors which predispose an individual to develop high grade conduction block post-TAVR is important.Various demographic factors,electrocardiographic features,anatomic factors and procedural characteristics have all been linked to the development of advanced conduction block and need for PPM following TAVR.Amongst these electrophysiological variables,most notably a prolonged QRS>120 ms regardless of the type of conduction block seems to be one of the strongest predictors on logistic regression models.The index study by Nwaedozie et al highlights that patients requiring PPM post-TAVR had higher odds of having a baseline QRS>120 ms and were more likely to be having diabetes mellitus that those who did not require PPM.

Misinterpretation of sleep-induced second-degree atrioventricular block

A number of publications have claimed that Mobitz type Ⅱ atrioventricular block(AVB)may occur during sleep.None of the reports defined type Ⅱ AVB and representative electrocardiograms were either misinterpreted or missing.Relatively benign Wenckebach type Ⅰ AVB is often misdiagnosed as Mobitz type Ⅱ which is an indication for a pacemaker.Review of the published reports indicates that Mobitz type II AVB does not occur during sleep when it is absent in the awake state.Conclusion:There is no proof that sleep is associated with Mobitz type Ⅱ AVB.

Transcatheter aortic valve replacement in low-risk young population:A double edge sword?

Since the advent of transcatheter aortic valve replacement(TAVR)in 2002,it has now become the default interventional strategy for symptomatic patients presenting with severe aortic stenosis,particularly in intermediate to highsurgical risk patients.In 2019,the United States Food and Drug Administration approved TAVR in low-risk patients based on two randomized trials.However,these breakthrough trials excluded patients with certain unfavorable anatomies and odd profiles.While currently there is no randomized study of TAVR in young patients,it may be preferred by the young population given the benefits of early discharge,shorter hospital stay,and expedite recovery.Nonetheless,it is important to ruminate various factors including lifetime expectancy,risk of pacemaker implantation,and the need for future valve or coronary interventions in young cohorts before considering TAVR in these patients.Furthermore,the data on long-term durability(>10 years)of TAVR is still unknown given most of the procedures were initially performed in the high or prohibitive surgical risk population.Thus,this editorial aims to highlight the importance of considering an individualized approach in young patients with consideration of various factors including lifetime expectancy while choosing TAVR against surgical aortic valve replacement.

Pacemaker post transcatheter aortic valve replacement:A multifactorial risk?

Pacemaker post-transcatheter aortic valve replacement is related to multifactorial risk.Nwaedozie et al brought to the body of evidence electrocardiogram and clinical findings.However,procedural characteristics have at least as much impact on the final need for a permanent pacemaker and potentially on the pacing rate.In this regard,long-term follow-up and understanding of the impact of long-term stimulation is of utmost importance.