Search

BACKGROUND: The clinical utilization of leadless pacemakers (LPs) as an alternative to traditional transvenous pacemakers is likely to increase with the advent of dual-chamber LP systems. Since device retrieval to allow LP upgrade or replacement will become an important capability, the first such dual-chamber, helix-fixation LP system (Aveir DR; Abbott, Abbott Park, IL) was specifically designed to allow catheter-based retrieval. In this study, the preclinical performance and safety of retrieving chronically implanted dual-chamber LPs was evaluated. METHODS: Atrial and ventricular LPs were implanted in the right atrial appendage and right ventricular apex of 9 healthy ovine subjects. After ?2 years, the LPs were retrieved using a dedicated transvenous retrieval catheter (Aveir Retrieval Catheter; Abbott) by snaring, docking, and unscrewing from the myocardium. Comprehensive necropsy/histopathology studies were conducted to evaluate device- and procedure-related outcomes. RESULTS: At a median of 1.9 years postimplant (range, 1.8-2.6), all 18 of 18 (100%) LPs were retrieved from 9 ovine subjects without complications. The median retrieval procedure duration for both LPs, from first-catheter-in to last-catheterout, was 13.3 minutes (range, 2.5-36.4). Postretrieval, all right atrial, and right ventricular implant sites demonstrated minimal tissue disruption, with intact fibrous tissue limited to the distal device body. No significant device-related trauma, perforation, pericardial effusion, right heart or tricuspid valve injury, or chronic pulmonary thromboembolism were observed at necropsy. CONCLUSIONS: This preclinical study demonstrated the safe and effective retrieval of chronically implanted, helix-fixation, dualchamber LP systems, paving the way for clinical studies of LP retrieval. [ABSTRACT FROM AUTHOR]

Lipomatous hypertrophy of the interatrial septum is a rare benign condition characterized by adipocyte hyperplasia with fat infiltration between the myocardial fibers in the interatrial septum. Although lipomatous hypertrophy does not occur only in the interatrial septum, its location in the interventricular septum is extremely rare. A 45-year-old woman with no medical or family history of cardiac disease presented with an episode of syncope. Transthoracic echocardiography revealed an echogenic mass in the interventricular septum and no outflow obstruction. The mass-like area showed fat tissue-specific features on computed tomography and magnetic resonance imaging, and furthermore, it showed late gadolinium enhancement. We diagnosed it as lipomatous hypertrophy of the interventricular septum. An implantable loop recorder documented paroxysmal complete atrioventricular block with presyncope. A permanent dual-chamber pacemaker was implanted. This is the first reported case of lipomatous hypertrophy of the interventricular septum treated with a pacemaker for complete atrioventricular block with syncope. We have described the case and the treatment strategy in detail. To understand lipomatous hypertrophy, a rare disorder, and its characteristics and differences between lipomatous hypertrophy and cardiac adipose tumors on computed tomography and magnetic resonance imaging. To learn about the appropriate treatment and clinical management of this benign condition and treat symptomatic patients. [ABSTRACT FROM AUTHOR]

• Noise-related interferences during exposureoccurred in 84% of the devices. • Potentially harmful effects were found in 34% of the ICDs. • Irreversible effects on battery life occurred in only non-MRI-compatible devices. • RTmay cause damage and malfunction in a consistent number of older-generations PMs and ICDs. Radiotherapy may cause malfunction of implantable cardioverter-defibrillators (ICDs) and pacemakers (PMs). We carried-out a multicentre randomized in-vitro study on 65 ICDs and 145 PMs to evaluate malfunctions during and after direct irradiation to doses up to 10 Gy. Three centres equipped with different linear accelerator and treatment-planning systems participated in the study. Computed Tomography (CT) acquisitions were performed to build the treatment plans. All devices were exposed to dose of 2, 5, or 10 Gy (6 MV). All devices underwent a baseline examination and 64 wireless real-time telemetry - transmissions (47 ICDs and 17 PMs) were monitored during photon exposures. All devices were interrogated after exposure and once monthly for six subsequent months. Fifty-four of the 64 wireless-enabled CIEDs (84.4%) recorded noise-related interferences during exposure. In detail, 40/47 ICDs (85.1%) reported interference, of which 16 ICDs (34%) reported potentially clinically relevant pacing inhibition and inappropriate detections. Following exposure, a soft reset occurred in 1/145 PM (0.7%) while 7/145 PMs (4.8%) reported battery issues. During the six-month follow-up, 1/145 PM (0.7%) reported a soft reset, while 12/145 more PMs (8.3%) and 1/64 ICD (1.5%) showed abnormal battery depletion. All reported issues occurred independently of exposure dose. Finally, irreversible effects on software and battery life occurred in only non-MRI-compatible devices. ICDs mostly featured real-time transient sensing issues, while PMs mostly experienced long-term battery or software issues that were observed immediately following radiation exposure and during follow-up. Irreversible effects on battery life and software occurred in only non-MRI-compatible devices. [ABSTRACT FROM AUTHOR]

The work presented describes the modeling of a measurement bench in the presence of an implantable single-chamber pacemaker in vitro subjected to a conducted disturbance. The source of disturbance is a sinusoidal electrical signal with amplitude of 10 V; the frequency ranges studied correspond to the frequencies of the electrical distribution network (50/60 Hz) and to the frequencies of domestic applications (10/25KHz). The numerical simulations were carried out according to two methods, the first based on the finite element method using the Comsol multiphysics software, the second is based on the impedance method. The results obtained by the two methods are in good agreement, and this will allow us to calculate the voltage induced between the ends of the stimulator. These results allowed us to validate the proposed model. [ABSTRACT FROM AUTHOR]

The atrioventricular node (AV) is considered the electrical connection between the atria and ventricles. There is an electrical pause between activation of the atria and the ventricles (PR segment), but to date the mechanism responsible for this interruption remains unclear. The present communication focuses on the hypothesis that magnetic field dynamics could provide the answer. Proof of this hypothesis is that in Wolff-Parkinson-White syndrome, where there is physical connection between the atria and ventricles (bundle of Kent), there is electrical AV continuity, no PR segment is detected, and catheter ablation of the abnormal bundle restores AV discontinuity. Spontaneous initiation of the heart at the level of the sinus node, the pacemaker of the heart, could also be explained via field dynamics. The known transmembrane pacemaker protein CHN4, present in both sinoatrial and AV nodal cells, could interact with field information to provide specificity in an electronic key-to-lock mechanism interaction. [ABSTRACT FROM AUTHOR]

Cardiac pacemakers using rate response technologies represent the effectiveness of increasing the heart rate and cardiac output during exercise. Minute ventilation (MV) sensors are popular and estimate rates using transthoracic impedance by emitting very low amperage short electrical current pulses between the pacemaker lead tip and pulse generator. We present a case of an incomplete pacemaker lead fracture developing inappropriate pacing inhibition due to oversensing caused by the electrical current emitted by the MV sensor. A permanent pacemaker replacement was performed, resulting in no further abnormal findings such as inappropriate pacing inhibition. < Learning objective: The minute ventilation (MV) sensor is estimated using the transthoracic impedance by emitting a very low amperage and short pulses of electrical current between the pacemaker lead tip and pulse generator. Therefore, if a fractured lead occurs, the voltage from the current pulses emitted for the MV sensor might be high enough to be oversensed as ventricular waves. We recommend that it is necessary to keep in mind the possibility of a fractured lead if oversensing of the thoracic impedance measurement current is observed.> [ABSTRACT FROM AUTHOR]

Persistent left superior vena cava (PLSVC) is a congenital anomaly that poses a unique challenge when implanting cardiac implantable electronic devices (CIEDs) from the left side. To date, only a few isolated case reports are available regarding biventricular pacemaker implantation via PLSVC. These reports lack procedural details and tips to overcome difficulties faced by the physician when performing this technically demanding procedure. In the present report, we describe a patient who successfully underwent biventricular pacemaker implantation via a PLSVC after transvenous extraction of an infected device from the contralateral side, and discuss the technical implications. [ABSTRACT FROM AUTHOR]

Background/purpose: In patients with right ventricular pacing, the ECG shows a left bundle branch block (LBBB) pattern. There are several criteria to diagnose ST-elevation myocardial infarction (STEMI) in patients with LBBB. The aim of this study was to validate and compare Sgarbossa's with two new scores - Selvester's and Smith's - in this context.Methods: We identified pacemaker patients submitted to coronary angiography due to acute coronary syndrome. ECGs were analyzed by 2 blinded cardiologists. STEMI was defined according to angiographic and biochemical criteria. Sensitivity, specificity, positive and negative predictive values were calculated.Results: Forty-three patients with ventricular pacing were included for analysis. STEMI was diagnosed in 26 patients (60%). The most sensitive score was Selvester's (38.5%; 95% CI: 20.2-59.4) while the most specific was Sgarbossa's (100%; 95% CI: 80.5-100).Conclusions: The sequential application of these scores proved to be clinically useful in the context of STEMI. [ABSTRACT FROM AUTHOR]

Introduction Solitary plasmacytoma of bone is a local primary bone tumour consisting of malignant plasma cells without systemic involvement. These tumours are known for large amount of blood loss, and the use of electrocautery is helpful in reducing blood loss and performing surgery in a relatively bloodless field; however, use of unipolar cautery in patients with indwelling cardiac pacemaker is known to cause arrhythmias and cardiac events. Minimally invasive techniques offer potential advantages over open techniques particularly in patients with spinal tumours, where massive amount of blood loss is expected, if open procedure is performed. Here, we present a case of solitary L3 plasmacytoma with progressive neurological deficit with chronic refractory anaemia with indwelling cardiac pacemaker treated by minimally invasive technique. Materials and methods A 71-year-old male presented with increasing back pain with Left L3 radiculopathy since 6 months and progressive left lower limb weakness since 5 days. The patient is a known case of chronic renal failure with chronic refractory anaemia. The patient has indwelling cardiac pacemaker for cardiac arrhythmias. Radiology was suggestive of L3 body plasmacytoma. L3 corpectomy and anterior column reconstruction with expandable cage and posterior stabilization by minimally invasive techniques were performed. Results Two years of follow-up showed no local recurrence. The patient is ambulatory unaided with no neurological deficit and backache. Discussion There is no consensus regarding appropriate surgical approach and perioperative strategies in treatment of solitary plasmacytoma. A solitary plasmacytoma was found in the spine of a patient with cardiac pacemaker where anaesthetic consideration, blood loss and the use of electrocautery were the limiting factors. Minimally invasive approach is a good option. [ABSTRACT FROM AUTHOR]

Background: Cardiac device implantation can be complicated by inability to adequately place leads because of significant lead capture issues. This study sought to determine whether there are genetic bases that underlie poor lead capture.Methods and Results: Retrospective review of all patients with structurally normal hearts who underwent new device implantation at Texas Children's Hospital between 2009 and 2014 was performed. Patients with inability to capture at 10 V or a final capture threshold ≥3 V at 0.4 ms during implant were analyzed. Among a total of 136 patients (median age, 13 years; range, 3 days to 46 years), 11 patients (8.1%) who underwent dual chamber device implantation had elevated thresholds in the atria (4), ventricle (3), or both chambers (4; atrial-lead threshold, 4.7±4.3 versus 0.7±0.3 V; ventricular-lead, 3.0±3.3 versus 0.7±0.3 V). All 11 patients presented with sinus node dysfunction and 10 had atrial arrhythmias. At implant, inability to find atrial capture was seen in 4 patients. Three demonstrated intermittent complete loss of ventricular capture after implantation: 1 has recurrent syncope, 2 eventually died. Genetic testing performed in 10 demonstrated 7 patients with 6 distinct SCN5A mutations, all predicted to be severe loss-of-function mutations by bioinformatic analyses. In the remaining patients, although putative pathogenic mutations were not found, multiple SCN5A polymorphisms were identified in 2 and a desmin mutation in 1.Conclusions: This study suggests that significant capture issues at implant may be because of loss-of-function SCN5A mutations, providing new insights into SCN5A function. Recognition of this association may be critical for planning device implantation strategies and patient follow-up. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: Even though ictal tachyarrhythmias are more common, ictal brady-asystole is more likely to be fatal, and yet is potentially preventable with pacemaker (PM) implantation. We sought to quantify the degree of association of PM placement in people with and without epilepsy, including neurological and cardiovascular cohorts. Methods: Retrospective cross-sectional analysis of the National Hospital Discharge database using International Classification of Diseases Clinical Modification (ICD-9-CM) codes. We identified people with and without epilepsy between 1990 and 2006. The epilepsy cohort was compared to patients without epilepsy and other cardiovascular and central nervous system (CNS) disease cohorts. Results: People with epilepsy had higher odds of temporary PM (TPM; OR 1.6) than patients without epilepsy, especially amongst males (OR 2.0), young- (OR 4.6) and middle-aged (OR 4.3) patients. The epilepsy cohort had significantly higher odds of TPM than demyelinating disease (OR 7.9) and migraine (OR 9.1) cohorts. Compared to stroke, people with epilepsy had higher odds of TPM in the male (OR 1.6) and middle-age (OR 2.4) subgroups. No significant association was seen with permanent PM (PPM). Conclusions: Our study demonstrates the high likelihood of TPM placement in epilepsy patients as compared to cohorts without epilepsy. Significant associations were seen especially in males and young- and middle-aged patients. Since demyelinating and migraine cohorts are somewhat similar to epilepsy patients in age and sex characteristics, the higher odds of TPM in epilepsy patients may be related to the disease mechanism causing brady-asystole; however this requires further study. [Copyright &y& Elsevier]

Abstract: We report the initiation of pacemaker-mediated tachycardia by a St Jude implantable cardioverter-defibrillator with a programmed Ventricular Intrinsic Preference algorithm used for minimizing or inhibiting right ventricular pacing. This feature prolongs the atrioventricular (AV) delay periodically to determine if ventricular sensed events follow atrial events. Retrograde ventriculoatrial conduction and pacemaker-mediated tachycardia were initiated by long extended AV delays of 300 and 400 milliseconds. The 400-millisecond AV delay consisted of the programmed sensed AV delay (100 milliseconds) plus the Ventricular Intrinsic Preference increment (200 milliseconds) plus 100 milliseconds imposed by the AutoCapture algorithm when it detected loss of ventricular capture. [Copyright &y& Elsevier]

Abstract: The integrate-and-fire cardiac pacemaker model of the pulse coupled oscillators was introduced by C. Peskin. Due to the function of the pacemaker, two famous synchronization conjectures for identical and not identical oscillators were formulated. There are still many issues related to the nature and types of couplings. The couplings may be impulsive, continuous, delayed or advanced, and oscillators may be locally or globally connected. Consequently, it is reasonable to consider various ways of synchronization, if one wants the biological and mathematical analyses to interact productively. We investigate the integrate-and-fire model in both cases–one with identical, and another with not quite identical oscillators. A combination of continuous and pulse couplings that sustain the firing in unison is carefully constructed. Moreover, we obtain conditions on the parameters of continuous couplings that make possible a rigorous mathematical investigation of the problem. The technique developed for differential equations with discontinuities at non-fixed moments and a special continuous map lies on the basis of the analysis. This is the first analytically derived synchronization result for a model with continuous couplings. Illustrative examples are provided. [Copyright &y& Elsevier]

Background: Lead complications are the main reason for reoperation after implantation of pacemakers (PM) or cardiac resynchronization therapy (CRT-P) devices. Objective: This study sought to describe the incidence of lead complications causing reoperation after device implantation and to identify risk factors for lead complications. Methods: A nationwide, population-based, historic cohort study was performed based on data from the Danish Pacemaker Register, which includes all Danish patients who received their first PM or CRT-P device from 1997 to 2008. Follow-up occurred 3 months after implantation. Results: The study population consisted of 28,860 patients. The incidence of any lead complication was 3.6%, encompassing right atrial (RA; 2.3%), right ventricular (2.2%), and left ventricular (4.3%) lead complications. The lead complication risk declined during the first part of the study period and remained stable after 2002. Multivariate analysis identified the following significant risk factors: chronic heart failure as indication (adjusted odds ratio (aOR) 3.0; 95% confidence interval [CI] 2.1 to 4.3), implantation in a nonuniversity center (aOR 1.4; 95% CI 1.2 to 1.6), inexperienced operator with <25 implantations (aOR 1.6; 95% CI 1.3 to 2.0), single-lead RA device (aOR 1.4; 95% CI 1.1 to 1.8), dual-chamber pacing device (aOR 1.6; 95% CI 1.4 to 1.9), CRT-P device (aOR 3.3; 95% CI 2.4 to 4.4) and passive-fixation RA lead (aOR 2.2; 95% CI 1.7 to 2.9). Conclusion: Lead complications causing reoperation remain a clinically important problem in device therapy. Mainly procedure-related factors were identified as independent risk factors for lead complications. [ABSTRACT FROM AUTHOR]

Copyright of IRBM is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Archives of Cardiovascular Diseases Supplements is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The diseases of the cardiovascular system are frequent with dogs and are due to a varied and many times complex etiology. The atrioventricular bloc was the first requirement for stimulation and still is the most common reason for stimulator implanting. The endocardial or pericardial (pacemaker) artificial electric stimulators represent the sole sustainable therapeutic solution. The case being the object of this work is a Boxer breed female, aged 12 years, who came to the Surgery Clinic of Spiru Haret University following a syncope and a pain of unknown origin occurring during the sleep. The diagnosis set was 2nd to 3rd Mobitz degree atrioventricular block and it was decided that the sole long term treatment is a cardiac pacemaker implant. Surgery was conducted under general anesthesia, by administering 0.02 - 0.04 mg/kg i.m. and Butorphanol 0.2 - 0.4 mg/kg i.m. as pre-medication. Induction was conducted with Propofol 4 - 6 mg/kg i.v. and maintenance was conducted with sevofluranum inhaled anesthesia. The epicardial pacemaker implant was made trans-diaphragmatically, the animal placed in decubitus dorsal position and under general anesthesia, with assisted ventilation and intense cardiac monitoring. The stimulator implanting, as an invasive procedure, though involving the risk of complications and failures, not only in the immediate post-surgery period, but also in the log run, was the sole effective solution in the given situation. [ABSTRACT FROM AUTHOR]

The article presents a historical background on the competing oscillators in cardiac pacemaking. The earliest models of cardiac rhythm focused on the interactions between surface membrane ion channels. The first cardiac cell model that incorporated the intracellular calcium signaling system was developed for sheep Purkinje fibers. After that, the Difrancesco-Noble Purkinje fiber model was developed and became the first to reproduce voltage waveforms similar to those observed in rabbit sinoatrial node (SAN) cells.

Abstract: Ictal asystole (IA) is a life-threatening complication of epilepsy and is a potential mechanism of sudden unexplained death in epilepsy (SUDEP). This entity has been proven by multiple case reports and small case series. The management of the patients with IA is still in early phase of discussion. We report a patient with medically intractable cryptogenic partial epilepsy for 27 years who presented with new onset drop attacks. During the epilepsy monitoring unit stay he was found to have a left fronto-temporal partial onset seizures which triggered brady-arrhythmia followed by asystole for 20s. A cardiac pacemaker was implanted and the patient was followed for 2 years. He continued to have simple and complex partial seizures but did not have drop attacks anymore. He still occasionally feels the activation of his pacemaker during simple partial phase of his seizures but the characteristic loss of muscle tone never happened again which made him highly satisfied. Our case demonstrates that IA can even happen decades after the onset of epilepsy. Cardiac pacemaker should be considered in all patients with IA as it prevents ictal falls and possibly SUDEP. [Copyright &y& Elsevier]

Myocardial perforation is a rare complication of permanent pacemaker implantation. While most of the perforations occur at the time of implantation or within the first 24 h, delayed myocardial perforations are very rare. The clinical course is extremely variable with some patients presenting completely asymptomatic, while others can develop cardiac tamponade and haemodynamic instability. We report an unusual case of a subacute ventricular perforation caused by a passive-fixation lead two weeks after implantation and we successfully managed to extract the lead under local anaesthesia, without the patient undergoing surgery, as recommended in the previously published reports. [ABSTRACT FROM AUTHOR]

• Mathcad and Maxwell simulation were used to compare the mutual inductance coefficients of wireless charging under different radius ratios and different distances. • The paper finds out the optimal radius ratio between the transmitting coil and the receiving coil, which greatly improves the transmission efficiency. • The new coil structure proposed in this paper can effectively improve the transmission efficiency of the cardiac pacemaker, and the structure can play an anti-migration effect. At present, wireless charging technology is widely used in implantable medical devices. However, the wireless charging system of implantable medical devices still faces problems such as low transmission efficiency and short transmission distance. A pacemaker is an implantable medical device. In view of the low transmission efficiency of the wireless charging system in current implantable cardiac pacemakers, this paper presents a new coil structure to achieve high efficiency transmission. The key to the design is to find the optimal radius ratio between the transmitting and receiving coils. The theoretical circuit diagram is given in the paper, and the theoretical analysis and formula derivation are carried out around the influence of radius ratio on the transmission efficiency and mutual inductance. Mathcad is used to simulate the influence of the radius ratio and transmission distance on the transmission efficiency and mutual inductance. Maxwell is further used to simulate magnetic field cloud diagrams under different radius ratios and transmission distances. Finally, the design parameters are used to build an experimental verification platform. Simulation and experiments show that the new coil structure proposed in this paper can improve the transmission efficiency of cardiac pacemaker. [ABSTRACT FROM AUTHOR]

Abstract: Ictal asystole is a presumably rare but potentially fatal complication of seizures, most often of temporal lobe origin. It is believed that at least some cases of sudden unexplained death in epilepsy (SUDEP) might be triggered by ictal bradycardia or asystole. Current standard practice is to implant a permanent pacemaker in these patients to prevent syncope and/or death. However, emerging data suggests that effective medical or surgical treatment of epilepsy might be enough to prevent cardiac asystole, eliminating the need for permanent pacemaker placement. We describe a case of new onset left frontal lobe epilepsy in a young athletic patient who presented with near-syncopal episodes but whose comprehensive work-up revealed frequent events of ictal bradycardia and asystole. He responded well to monotherapy using oxcarbazepine, avoiding a permanent pacemaker. [Copyright &y& Elsevier]

Potential candidates for cardiac resynchronization therapy (CRT) include patients with symptomatic congestive heart failure despite optimal medical therapy, who also have evidence of ventricular dyssynchrony, particularly left bundle branch block, with QRS duration in excess of 150 ms. Dyssynchrony may additionally be identified by echo-Doppler examination and tagged magnetic resonance imaging. Improved exercise capacity and quality of life, reduced sympathetic activation and fewer ventricular tachyarrhythmias are potential benefits of CRT. Ongoing trial results will be required to refine patient selection criteria and to demonstrate the possibility for prognostic as well as symptomatic benefit. [Copyright &y& Elsevier]