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.

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.

Evaluation of Safety and Efficacy of Qinming8631 DR Implantable Cardiac Pacemaker in Chinese Patients： A Prospective, Multicenter, Randomized Controlled Trial of the First Domestically Developed Pacemaker of China

Background：High cost of imported pacemakers is a main obstacle for Chinese patients suffering from bradyarrhythmia,and a domestically developed pacemaker will help lower the burden.This study aimed to evaluate the safety and efficacy ofQinming8631 DR （Qinming Medical,Baoji,China）,the first domestically developed dual-chamber pacemaker of China,compared with a commercially available pacemaker Talos DR （Biotronik,Berlin,Germany） in Chinese patients.Methods：A prospective randomized trial was conducted at 14 centers in China.Participants were randomized into trial （Qinming8631 DR） and control （Talos DR） groups.Parameters of the pacing systems were collected immediately after device implantation and during follow-ups.The effective pacing rate at 6-month follow-up was recorded as the primary end point.Electrical properties,magnet response,single-and double-pole polarity conversion,rate response function,and adverse events of the pacing system were analyzed.The Cochran-Mantel-Haenszel Chi-square test,paired t-test,and Wilcoxon signed-rank test were used for measuring primary qualitative outcomes and comparing normally and abnormally distributed measurement data.Results：A total of 225 patients with a diagnosis ofbradyarrhythmia and eligible for this study were randomly enrolled into the trial （n =113） and control （n =112） groups.They underwent successful pacemaker implantation with acceptable postoperative pacing threshold and sensitivity.Effective pacing rates of trial and control groups were comparable both in the full analysis set and the per protocol set （81.4% vs.79.5%,P =0.712 and 95.4% vs.89.5%,P =0.143,respectively）.In both data sets,noninferiority of the trial group was above the predefined noninferiority limit（-9.5%）.Conclusions：This study established the noninferiority ofQinming8631 DR to Talos DR.The safety and efficacy ofQinming8631 DR pacemaker were comparable to those of Talos DR in treating patients with cardiac bradyarrhythmia.

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.

Improved Cardiac Contractility of Human Recombinant Growth Hormone on the Congestive Heart Failure of Pig

The enhanced cardiac contractility effect of human recombinant growth hormone (hr-GH) on the congestive heart failure (CHF) was studied on the pig. To build a pig model of congestive heart failure, a temporary artificial cardiac pacemaker was implanted in the pig’s body and paced at 220 beats to 240 beats per minute for 1 week. After the model of congestive heart failure was successfully set up, the frequency of the pacemaker was changed to 150 beats to 180 beats per minute to maintain the CHF model stable. Pigs were divided into three groups: The hr-GH group in which 0.5 mg/kg per day of hr-GH was administrated intramuscularly for 15 days, the injection control group in which an equal amount of physiological saline was injected intramuscularly, and a normal control group. The left ventricular diastolic end pressure was (10.60±2.41) mmHg in the hr-GH group, but (19.00±3.81) mmHg in the saline control group (P<0.01); Cardiac output was (1.86±0.13) L/min in the hr-GH group, but (1.56±0.18) L/min in the saline control group (P<0.05); Peripheral vascular resistance was (56.88±7.51) mmHg·(L/min) -1 in the hr-GH group, whereas (70.30±11.59) mmHg·(L/min) -1 in the saline control group (P<0.05); +dp/dt max was (2900±316.23) and (2280±286.36) in the hr-HG group and the saline control group respectively (P<0.05). The results show that hr-GH enhances myocardial contractility of CHF, and the CHF model built by a temporary artificial cardiac pacemaker at a high rate of stimulation is reasonable and applicable.

Clinical application of temporary pacemaker insertion guided by bedside ultrasound in elder and critical patients

Background Ultrasound-guided temporary pacemaker implantation has been proven safe and efficient. However, few studies have focused on elder and critical patients. Methods Twelve elder and critical patients underwent temporary cardiac pacing through the jugular vein or subclavian vein, with bedside ultrasound images to assist the placement of electrode within the right ventricle. Results Ultrasound-guided temporary cardiac pacemaker insertion was successful in all of the 12 patients. Electrodes were sent into the right ventricle correctly with the help of ultrasound imaging. In all cases, temporary pacemaker functioned well without procedure-related complications. Conclusion Temporary cardiac pacing guided by ultrasound is safe and effective in elder and critical patients, which is worth of promoting, especially in intensive care unit.