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.

Bow-and-arrow sign on point-of-care ultrasound for diagnosis of pacemaker lead-induced heart perforation:A case report and literature review

BACKGROUND Pacemaker lead-induced heart perforation is a rare but life-threatening complication of pacemaker implantation,and timely diagnosis remains a challenge for clinicians.Here,we report a case of pacemaker lead-induced cardiac perforation rapidly diagnosed by a“bow-and-arrow”sign on point-of-care ultrasound(POCUS).CASE SUMMARY A 74-year-old Chinese woman who had undergone permanent pacemaker implantation 26 d before suddenly developed severe dyspnea,chest pain,and hypotension.The patient had received emergency laparotomy for an incarcerated groin hernia and was transferred to the intensive care unit 6 d before.Computed tomography was not available due to unstable hemodynamic status,so POCUS was performed at the bedside and revealed severe pericardial effusion and cardiac tamponade.Subsequent pericardiocentesis yielded a large volume of bloody pericardial fluid.Further POCUS by an ultrasonographist revealed a unique“bow-and-arrow”sign indicating right ventricular(RV)apex perforation by the pacemaker lead,which facilitated the rapid diagnosis of lead perforation.Given the persistent drainage of pericardial bleeding,urgent off-pump open chest surgery was performed to repair the perforation.However,the patient died of shock and multiple organ dysfunction syndrome within 24 h post-surgery.In addition,we also performed a literature review on the sonographic features of RV apex perforation by lead.CONCLUSION POCUS enables the early diagnosis of pacemaker lead perforation at the bedside.A step-wise ultrasonographic approach and the“bow-and-arrow”sign on POCUS are helpful for rapid diagnosis of lead perforation.

Perioperative coagulation activation after permanent pacemaker placement

BACKGROUND Bradyarrhythmias are typically treated with permanent pacemakers(PM). The elimination of bradyarrhythmia by PM implantation improves the patient’s quality of life and prognosis, but it can also result in a number of sequalae. It is still unclear how PM implantation affects the hemostasis system’s parameters and how such parameters relate to different consequences after PM placement.AIM To assess the blood coagulation factor activity in PM patients throughout the perioperative period.METHODS Patients treated in the Department of Surgical Therapy of Cardiac Arrhythmias and Pacing at the Ryazan State "Regional Clinical Cardiology Dispensary" from April 2020 to December 2021 were included in the study. Before surgery, 7 and 30 d after PM placement, peripheral venous blood samples were withdrawn to measure the level of blood coagulation factor Ⅰ(FⅠ) and the activity of blood coagulation factors Ⅱ(FⅡ), Ⅴ(FⅤ), Ⅶ(FⅦ), Ⅷ(FⅧ), ⅸ(Fⅸ), ⅹ(Fⅹ), Ⅺ(FⅪ), Ⅻ(FⅫ). We used an automatic coagulometer Sysmex CA 660(Sysmex Europe, Germany) and reagents from Siemens(Siemens Healthcare Diagnostics Products GmbH, Germany).RESULTS The study included 146 patients. The activity of factors FⅤ [147.7(102.1-247.55)% vs 103.85(60-161.6)% vs 81.8(67.15-130.65)%, P = 0.002], FⅧ [80.4(60.15-106.25)% vs 70.3(48.5-89.1)% vs 63.7(41.6-88.25)%, P = 0.039], Fⅸ [86.2(70.75-102.95)% vs 75.4(59.2-88.3)% vs 73.9(56.45-93.05)%, P = 0.014], Fⅹ [188.9(99.3-308.18)% vs 158.9(83.3-230)% vs 127.2(95.25-209.35)%, P = 0.022], FⅪ [82.6(63.9-103.6)% vs 69.75(53.8-97.6)% vs 67.3(54.25-98.05)%, P = 0.002], FⅫ [87.6(67.15-102.3)% vs 78.9(63.4-97.05)% vs 81.2(62.15-97.4)%, P < 0.001] decreased at 7 and 30 d after surgery;FⅡ activity [157.9(109.7-245.25)% vs 130(86.8-192.5)% vs 144.8(103.31-185.6)%, P = 0.021] decreased at 7 d and increased at 30 d postoperatively. There were no statistically significant changes in the FVII activity within 30 d after PM placement [182.2(85.1-344.8)% vs 157.2(99.1-259)% vs 108.9(74.9-219.8)%, P = 0.128]. Subgroup analysis revealed similar changes only in patients on anticoagulant therapy. FⅫ activity decreased in patients on antiplatelet therapy [82(65.8-101.9)% vs 79.9(63.3-97.1)% vs 89.7(75.7-102.5)%, P = 0.01] 7 d after surgery, returning to baseline values at 30 d postoperatively.CONCLUSION PM placement and anticoagulant therapy were associated with decreased activity of clotting factors FⅤ, FⅧ, Fⅸ, Fⅹ, FⅪ, FⅫ in the postoperative period. FⅧ activity did not decrease within 30 d after PM placement, which may indicate endothelial injury caused by lead placement.

Hyperpolarization-activated Cyclic nucleotide-gated Channel and Cardiac Biological Pacemaker:Part Ⅰ

Hyperpolarization-activated cyclic-nucleotide-gated (HCN) channels in the heart modulate cardiac automaticity via the hyperpolarization-activated cation current ( named Ⅰf, Ⅰh, or Ⅰq). Recent studies have unveiled the molecular identity of HCN (HCN1-4) channels. HCN isoforms are unevenly expressed in the heart, even in the sinoatrial node. Features of HCN currents have been characterized in cardiac and other types of cells or in cell lines transfected with the HCN isoforms. The factors modulating Ih and the physiological significance of HCN channels in the heart have been extensively investigated in recent years. The hypothesis for transplanting and/or creating biological pacemakers to replace diseased sinoatrial and/or atrioventricular nodes has been postulated and tested in animal models. Local overexpression of HCN2 channels in the left atrium or in the left conductive bundle branch of the left ventricle via gene delivery induced significant Ⅰh and escape rhythms during vagal stimulation in canines. In addition, implantation of human mesenchymal stem cells with overexpression of HCN2 channels to the canine left ventricular wall was associated with formation of spontaneous escape rhythms of left-sided origin during vagal-stimulation-induced sinus arrest. This preliminary data suggest that the use of HCN channels may hold great promise in,the development of biological pacemakers.

EFFECT OF THE EXCITATION OF ADRENOCEPTORS ON THE PACEMAKER CURRENT I_f OF SHEEP CARDIAC PURKINJE FIBRES IN “ISCHEMIA”SOLUTION

The effect of ischemia like solution and high concentration of isoprenaline and Phenylephrine in that solution on normal pacemaker current If of sheep cardiac Puekinje fibres were observed After perfusing the preparations with “ischemia” solution 15, 30, and 60 min, the amplitude of If current at all measured membrane potentials (from -60 to -120 mV) decreased (n=7,p<0.05)and the activation curve of If current shiftea to left side,E0.5 changed from control value -85.0±3.7 mV to -91.7±4.1 mV at 30 min. Isoprenaline 1×10-6mol/L could increase the amplitude of If current in “ischemia” solution (n= 10, P<0.05) and shift the activation curve of If current back to right side, but it could not completely reverse the inhibitory effect of“ ischemia“. In the presence of propranolol 5 ×10-7 mol/L, 5×10-5 mol/L phenylephrine decreased the amplitude of If current further in “ischemia” solution (n= 7, P<0.05-0.01), the activatior curve of If current shifted to left side further. The above results indicate that the normal pacemaker current was inhibited in “ischemia” condition even in the presence of high concentration of beta and alpha adrenoceptor agonists so the genesis of ischemic ventricular arrhythmia is hardly due to the abnormal enhancement of normal ventricular pacemaker activity.

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.

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.

In vivo cardiac pacemaker function of differentiated human mesenchymal stem cells from adipose tissue transplanted into porcine hearts

BACKGROUND Mesenchymal stem cells(MSC)modified by gene transfer to express cardiac pacemaker channels such as HCN2 or HCN4 were shown to elicit pacemaker function after intracardiac transplantation in experimental animal models.Human MSC derived from adipose tissue(haMSC)differentiate into cells with pacemaker properties in vitro,but little is known about their behavior after intracardiac transplantation.AIM To investigate whether haMSC elicit biological pacemaker function in vivo after transplantation into pig hearts.METHODS haMSC under native conditions(nhaMSC)or after pre-conditioning by medium differentiation(dhaMSC)(n=6 pigs each,5×106 cells/animal)were injected into the porcine left ventricular free wall.Animals receiving PBS injection served as controls(n=6).Four weeks later,total atrioventricular(AV)-block was induced by radiofrequency catheter ablation,and electronic pacemaker devices were implanted for backup stimulation and heart rate monitoring.Ventricular rate and rhythm of pigs were evaluated during a follow-up of 15 d post ablation by 12-lead-ECG with heart rate assessment,24-h continuous rate monitoring recorded by electronic pacemaker,assessment of escape recovery time,and pharmacological challenge to address catecholaminergic rate response.Finally,hearts were analyzed by histological and immunohistochemical investigations.RESULTS In vivo transplantation of dhaMSC into the left ventricular free wall of pigs elicited spontaneous and regular rhythms that were pace-mapped to ventricular injection sites(mean heart rate 72.2±3.6 bpm;n=6)after experimental total AV block.Ventricular rhythms were stably detected over a 15-d period and were sensitive to catecholaminergic stimulation(mean maximum heart rate 131.0±6.2 bpm;n=6;P<0.001).Pigs,which received nhaMSC or PBS presented significantly lower ventricular rates(mean heart rates 47.2±2.5 bpm and 37.4±3.2 bpm,respectively;n=6 each;P<0.001)and exhibited little sensitivity towards catecholaminergic stimulation(mean maximum heart rates 76.4±3.1 bpm and 60.5±3.1 bpm,respectively;n=6 each;P<0.05).Histological and immunohistochemical evaluation of hearts treated with dhaMSC revealed local clusters of transplanted cells at the injection sites that lacked macrophage or lymphocyte infiltrations or tumor formation.Intense fluorescence signals at these sites indicated membrane expression of HCN4 and other pacemaker-specific proteins involved in cardiac automaticity and impulse propagation.CONCLUSION dhaMSC transplanted into pig left ventricles sustainably induced rate-responsive ventricular pacemaker activity after in vivo engraftment for four weeks.The data suggest that pre-conditioned MSC may further differentiate along a pacemakerrelated lineage after myocardial integration and may establish superior pacemaker properties in vivo.

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.

Cardiac Pacemaker and Wireless Capsule Endoscopy Interference: Case Report in a Patient with Gastric Vascular Ectasias

Wireless capsule endoscopy is a new endoscopic tool for the diagnosis and management of small bowel diseases. The main indication at present is the evaluation of GI bleeding of obscure origin, Crohn’s disease, coeliac disease and small bowel tumors. Studies suggest that capsule endoscopy is associated with few adverse events. Whether cardiac pacemaker may interfere with capsule endoscopy is still a controversial issue. We here report a case showing that there is a possibility of interference between the two procedures, cardiac pacemaker affecting the proper functioning of capsule endoscopy and that this is related to the distance between the pacemaker and the recorder.

On Practice of the Effect of Systematic Family Nursing Guidance on the Quality of Life of Elderly Patients with Implanted Cardiac Pacemaker

Objective: To inquire into the effect of systematic family nursing guidance on improving the Quality of Life for elderly patients with implanted cardiac pacemaker. Methods: 41 elderly patients in accordance with the corresponding requirements were studied after offering systematic family nursing guidance and surveyed through the questionnaires about the QOL (quality of life) respectively 1 month, 3 months and 6 months after leaving hospital. Results: Compared with that of 1 month and 3 months after the operation, the questionnaire scores for 6 months after the operation were found to have significant improvement, and the differences were statistically significant. Conclusion: Systematic family nursing guidance can effectively improve the QOL for elderly patients with implanted cardiac pacemaker, which makes them spend their old age in comfort and happiness.

Do Patients with Asymptomatic Congenital Complete Heart Block Require a Pacemaker for Non-Cardiac Surgery?

The appropriate preparation of the patient with asymptomatic congenital complete heart block (CCHB) and a narrow QRS complex for elective non-cardiac surgery is controversial. Prophylactic temporary pacemaker insertion is associated with well-defined risks, and less invasive techniques exist to treat transient, hemodynamically significant intraoperative brady-arrhythmias. The present case report details the performance of general anesthesia for arthroscopic knee surgery in an adult patient with this condition without a pacemaker. Documentation of preoperative chronotropic competence with isoproterenol may be of value in deciding whether to proceed without temporary pacing capability in this setting.

Transhepatic venous approach to permanent pacemaker placement in a patient with limited central venous access

The end-stage renal disease population poses a challenge for obtaining venous access required for life-saving invasive cardiac procedures. In this case report, we describe an adult patient with end-stage renal disease in whom the hepatic vein was the only available access to implant a single-lead permanent cardiac pacemaker. A 63-year-old male with endstage renal disease on maintenance hemodialysis and permanent atrial fibrillation/atrial flutter presented with symptomatic bradycardia. Imaging studies revealed all traditional central venous access sites to be occluded/non-accessible. With the assistance of vascular interventional radiology, a trans-hepatic venous catheter was placed. This was then used to place a right ventricular pacing lead with close attention to numerous technical aspects. The procedure was completed successfully with placement of a single-lead permanent cardiac pacemaker.

Pacemaker implantation in a patient with brugada and sick sinus syndrome

Brugada syndrome (BrS) is a rare and inherited primary arrhythmic syndrome characterized by ST-segment elevations in the right precordial leads (V1 -V3 ) with an increased risk of sudden cardiac death (SCD). Arrhythmias in BrS are often nocturne, and brady-arrhythmias are often seen in patients with loss-of-function mutations in SCN5A . In this case-report we present a 75-year old woman referred to our outpatient clinic for inherited cardiac diseases for a familial clinical work-up. Since childhood she had suffered from dizziness, absence seizures, and countless Syncope's. In 2004 sick sinus syndrome was suspected and she wastreated with implantation of a pacemaker (PM) at another institution. An inherited cardiac disease was one day suddenly suspected, as the patient had a 61-year old brother who was diagnosed with symptomatic BrS, and treated with an implantable cardioverter defibrillator (ICD) after aborted SCD. A mutation screening revealed a SCN5A [S231CfsX251 (c.692-693delCA )] loss-of-function mutation not previously reported, and as a part of the cascade screening in relatives she was therefore referred to our clinic. In the 7 year period after PM implantation she had experienced no cardiac symptoms, although her electrocardiogram changes now were consistent with a BrS type 1 pattern. A genetic test confirmed that she had the same mutation in SCN5A as her brother. In this case-report we present a loss-of function mutation in SCN5A not previously associated with BrS nor presented in healthy controls. Sinus node dysfunction has previously been documented in patients with symptomatic BrS, which suggests it is not a rare concomitant. The only accepted treatment of BrS is today implantation of an ICD. In the future studies should evaluate if PM in some cases of symptomatic BrS can be used instead of ICDs in patients with a loss-of-function SCN5A

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.

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.

Right Ventricular Perforation after Pacemaker Implantation in an Elderly Woman： A Case Report

Background： Cardiac pacing is a proven and effective treatment used worldwide with a low incidence of complications depending on the patient group. Late lead perforation is a rare complication without a standard treatment. Case summary： We report a case of a 98-year old woman submitted to pacemaker implantation due to symptomatic second-degree atrio-ventricular block. After two days she returned to the hospital with thoracic pain and was diagnosed with RV （right ventricular） lead perforation. She was submitted to cardiac surgery with lead extraction and RV repair. Discussion： There are two major types of complications after pacemaker implantation, mechanical and infection. Reported perforation rates after pacemaker implantation range from 0.1%-0.8%. While acute lead perforation is very well described, late lead perforation is only described in case reports with a low rate of tamponade or death. Management of subacute or delayed RV lead perforation is not well defined due to very limited data. Question remains on whether to extract the lead or not.

Recent impact study of automatic search function of the pacemaker atrial hysteresis on atrial arrhythmias

Objective:To explore the recent influences of pacemaker with automatic search function of atrial hysteresis on atrial arrhythmias,and to evaluate it clinical efficacy and safety.Methods:Indentify ADx DDD 5286 implanted dual chamber pacemaker for sick sinus syndrome in 43 cases.Automatic search of atrial lag was not opened with after pacemaker implantation,and the pacemaker settings were kept.Follow-up program after 3 months,DDD mode with automatic search of atrial lag was opened,and this mode was followed up for 6 months,comparing the atrial pacing percentage and DCG atrial tachyarrhythmias of pacemaker implantation to opening atrium lag mode.Results:Compared with the preoperative and operative 3 months later,dynamic electrocardiogram(DCG)24 h showed that the number of atrial premature beats(APB)and atrial tachycardia,atrial fibrillation(AF)array increased(p<.05);the cases of APB,atrial tachycardia and AF episodes were also increased(p<.05).Compared with the automatic search function in atrial hysteresis model opened with and not opened:atrial pacing percentage decreased[0.54(0.41,0.71)vs.0.82(0.65,0.93),p<.05];DCG 24 h showed that the number of APB,AF episodes was reduced(p<.05).Conclusions:Automation search function in atrial hysteresis model can obviously reduce the proportion of atrial pacing,reduce the occurrence of atrial arrhythmias;opened with automatic search function in atrial hysteresis model was safe and reliable.

Feasibility of MRI in Patients with Non-Pacemaker/Defibrillator Metallic Devices and Abandoned Leads

Objective: To evaluate feasibility of MRI in patients with non-pacemaker (PM)/Implantable cardioverter defibrillator (ICD) metallic devices and abandoned leads. Background: Relative safety of MRI performed using specified protocol has been established in MR non-conditional PM/ICDs. With limited safety data, many non-PM/ICD metallic devices and abandoned leads continue to be a contraindication for MRI. Methods: We retrospectively analyzed consecutive patients with extra-cardiac devices, non-programmable cardiac devices, and abandoned leads, who underwent MRI (GE 1.5 Tesla, WI) at a single tertiary care center over a span of 13 years. Scan protocol was designed to maintain specific absorption rate (SAR) < 4.0 W/kg and scan time < 60 minutes. Results: The cohort comprised 127 MRI exams representing 94 patients, with 13 patients having two or more scans. The devices consisted of: 23 vagal nerve stimulators (VNS), 22 implantable loop recorders, 16 spinal stimulators, 5 peripheral nerve stimulators, 3 bladder stimulators, 2 deep brain stimulators, 1 gastric stimulator, 1 bone stimulator, 1 WATCHMAN device, 22 abandoned PM/lCD leads and 1 VNS lead. There was no immediate (peri-MRI exam) morbidity or mortality. Patients did not report any discomfort, palpitations, heating, or sensation of device migration during the exam. Local follow-up data was available in 65% (100% for thoracic imaging) with a mean of 190 ± 475 days (median 13 days). No device malfunction was reported during follow-up. Conclusions: With appropriate precautions, MRI is feasible in patients with extracardiac devices, nonprogrammable cardiac devices, and abandoned leads.