Intracardiac Pacemaker Research Articles

A self-powered intracardiac pacemaker in swine model

Harvesting biomechanical energy from cardiac motion is an attractive power source for implantable bioelectronic devices. Here, we report a battery-free, transcatheter, self-powered intracardiac pacemaker based on the coupled effect of triboelectrification and electrostatic induction for the treatment of arrhythmia in large animal models. We show that the capsule-shaped device (1.75 g, 1.52 cc) can be integrated with a delivery catheter for implanting in the right ventricle of a swine through the intravenous route, which effectively converts cardiac motion energy to electricity and maintains endocardial pacing function during the three-week follow-up period. We measure in vivo open circuit voltage and short circuit current of the self-powered intracardiac pacemaker of about 6.0 V and 0.2 μA, respectively. This approach exhibits up-to-date progress in self-powered medical devices and it may overcome the inherent energy shortcomings of implantable pacemakers and other bioelectronic devices for therapy and sensing.

Abstract 14531: Intracardiac versus Transvenous Pacemaker Implantation: Impact on Clinical Outcomes and Healthcare Utilization

Introduction: Permanent pacemakers are frequently used to treat disorders of cardiac rhythms. Recently, intracardiac (leadless) pacemakers offer potential treatment with an alternative insertion procedure due to their novel design. Literature comparing hospitalization outcomes between the devices is scarce. We aim to assess the impact of intracardiac pacemakers on readmissions and hospitalization trends. Methods: We analyzed the National Readmissions Database (NRD) from 2016 to 2019 seeking patients admitted for sick sinus syndrome, second-degree or third-degree AV block who received either a transvenous pacemaker or an intracardiac pacemaker. Patients were stratified by device type and assessed for 30-day readmissions, inpatient mortality, and length of stay. Descriptive statistics, Cox proportional hazards and multivariate regressions were used to compare the groups. Results: During the studied period, 21,782 patients met the inclusion criteria. Transvenous pacemakers were implanted in 17,677 patients and intracardiac pacemakers implanted in 4,017 patients. The mean age was 81.07 years, and 45.52% were female. No statistical difference was noted for readmissions (HR 1.14, 95% CI 0.92 - 1.41, p = 0.225) and inpatient mortality (HR 1.36, 95% CI 0.71 - 2.62, p = 0.352) between transvenous and intracardiac groups. Kaplan-Meier curves for readmission and mortality are presented in Figure 1A and 1B, respectively. Multivariate linear regression revealed that length of stay was 0.54 (95% CI 0.26 - 0.83, p < 0.001) days longer for intracardiac group. Conclusion: Hospitalization outcomes associated with intracardiac pacemakers are comparable to traditional transvenous pacemakers. Patients may benefit from the use of this new device without incurring additional resource utilization. Further studies are needed to compare long term outcomes between transvenous and intracardiac pacemakers.

Abstract 15725: Non Existing Pacemaker: A Complication of Kyphoplasty

Introduction: Diagnosis of cement emboli remains challenging due to heterogenicity of diagnostic findings. We describe a case of cement embolism interpreted as abandoned pacemaker leads. Case description: A 76-year-old female underwent lumbar kyphoplasty. In the post-anesthesia care unit, she developed multiple asymptomatic episodes of non-sustained ventricular tachycardia. Her lab work including basic metabolic panel, electrolytes, and troponin was unremarkable. A transthoracic echocardiogram (TTE) revealed intracardiac foreign body interpreted as abandoned pacemaker wires originating at the superior vena cava with one terminating in the right ventricular (RV) apex and the other in the right atrial (RA) appendage (Figure 1). Chest computer tomography (CT) confirmed intracardiac pacemaker wires. The patient denied any history of pacemaker placement. TTE and CT images were reviewed again with multiple other opinions stating that the foreign body represented dense cement from the vertebral body. It exited through a paravertebral vein into the inferior vena cava making its way to the right heart (Figure 2). Coronary angiography confirmed an elongated cement embolus. The patient underwent cement removal through sternotomy. Conclusions: Diagnosis of cement embolism may remain challenging as it can mimic any foreign bodies including pacemaker wires. Suspicion for the diagnosis should remain high in any patient who underwent kyphoplasty and developed cardiac arrhythmias or other cardiac symptoms. Image 1. A - Pacemaker lead passing through RA to the RV. Image 2. A- cement material in the right heart. B- Cement extravasating through right paravertebral vein.

Early trends in leadless pacemaker implantation: Evaluating nationwide in-hospital outcomes.

Single-chamber leadless intracardiac pacemaker (LICP) implantation was approved in 2016 in the United States. However, little is known regarding trends in real-world utilization and complication rates. The purpose of this study was to assess nationwide demographics, trends, and outcomes among hospitalizations with LICP implantation in the United States. Using the National Inpatient Sample, we identified all hospitalizations with LICP or transvenous pacemaker implantation as a comparator between 2017 and 2019. We evaluated baseline patient characteristics, admitting diagnoses, procedural complications, lengths of stay, discharge dispositions, and all-cause mortality. The majority of LICP recipients were elderly (75.4 ± 12.8 years), male (55.2%), and White (76.8%) compared to Black (9.8%), or Hispanic (7.3%). Between 2017 and 2019, the average age increased along with the prevalence of heart failure, atrial fibrillation, and malignancy among recipients. Most hospitalizations were emergent (84.5%). Between 2017 and 2019, pooled procedural complications decreased significantly (10.8% vs 7.9%; P <.001), primarily due to declining infection and device retrieval rates. In-hospital mortality also decreased significantly (8.2% vs 4.2%; P <.001). History of cardiogenic shock or cardiac device infection was associated with the greatest mortality or complication risk. Compared to transvenous pacemaker, LICP implantation was associated with lower complication rates (8.6% vs 11.2%) but greater mortality (5.2% vs 1.3%; P <.001). Nationwide LICP implantations were performed in patients of increasing age, comorbidities, and acuity of illness. In-hospital mortality and procedure-related complications declined in the first 3 years after approval of LICP implantation and may reflect improving operator experience. Increased mortality compared with transvenous pacemaker implant remains a concern.

Abstract 11217: Adverse Events Associated with AV Node Ablation in Patients with an Implanted Leadless Pacemaker

Introduction: The Micra leadless intracardiac pacemaker (LICP) is an FDA-approved right ventricular pacemaker that has been available worldwide since 2016. It is frequently implanted in patients who have atrial fibrillation and who undergo atrioventricular node ablation (AVN-AB) for rate control. The potential adverse effects of AVN-AB on LICP performance and function are unknown. Hypothesis: AVN-AB may increase LICP pacing thresholds and/or cause exit block or damage the LICP's electronics. Methods: The FDA Manufacturers and User Facility Device Experience (MAUDE) database was searched for Micra LICP adverse events associated with AVN-AB that were submitted by the manufacturer and received by the Food and Drug Administration from 2016-April 2021. Results: The search found 19 cases of pacing threshold elevation following AVN-AB that were performed during (n=9) or after (n=10) LICP implantation. Exit block resulted in asystole or marked bradycardia in 12 patients (63.2%); 2 of these patients required cardiopulmonary resuscitation. In 8 patients, a persistently high threshold or exit block required LICP replacement with either a new LICP or a transvenous pacemaker. Four explanted LICPs were returned and analyzed by the manufacturer and no pulse generator electronic abnormalities were found. Conclusions: AVN-AB during or after LICP implantation may result in persistently high pacing thresholds or exit block and necessitate LICP replacement; this appears to be a local effect at the LICP electrode-tissue interface rather than effects on LICP electronic function. Additional clinical safety data are needed, especially since patients may be rendered pacemaker-dependent after AVN-AB.

B-PO02-037 INCREASING NUMBER OF SERIOUS ADVERSE EVENTS DURING AND AFTER LEADLESS PACEMAKER IMPLANTATION

The leadless intracardiac pacemaker (LICP) was developed to avoid the complications of transvenous pacemakers, including lead failure and pocket infection. The Micra™ LICP pacemaker was FDA approved in 2016 after a pivotal clinical trial demonstrated safety and efficacy. Few serious adverse events (SAEs) during or immediately after Micra implantation have been reported in the medical literature.

Major adverse clinical events associated with implantation of a leadless intracardiac pacemaker

Leadless intracardiac pacemakers were developed to avoid the complications of transvenous pacing systems. The Medtronic Micra™ transcatheter pacemaker is one such system. We found an unexpected number of major adverse clinical events (MACE) in the Food and Drug Administration's Manufacturers and User Facility Device Experience (MAUDE) database associated with Micra implantation. The purpose of this study was to describe these MACE and compare them to implant procedure MACE in MAUDE for Medtronic CapSureFix™ active-fixation transvenous pacing leads. During January 2021, we queried the MAUDE database for reports of MACE for Micra pacemakers and CapSureFix leads using the simple search terms "death," "tamponade," and "perforation." Reports from 2016-2020 were included. The search identified 363 MACE for Micra and 960 MACE for CapSureFix leads, including 96 Micra deaths (26.4%) vs 23 CapSureFix deaths (2.4%) (P <.001); 287 Micra tamponades (79.1%) vs 225 tamponades for CapSureFix (23.4%) (P <.001); and 99 rescue thoracotomies for Micra (27.3%) vs 50 rescue thoracotomies for CapSureFix (5.2%) (P <.001). More Micra patients required cardiopulmonary resuscitation (21.8% vs 1.1%) and suffered hypotension or shock (22.0% vs 5.8%) than CapSureFix recipients (P <.001). Micra patients were more likely to survive a myocardial perforation or tear if they had surgical repair (P = .014). Micra leadless pacemaker implantation may be complicated by myocardial and vascular perforations and tears that result in cardiac tamponade and death. We estimate the incidence is low (<1%). Rescue surgery to repair perforations may be lifesaving. MACE are significantly less for implantation of CapSureFix transvenous ventricular pacing leads.

Nanostim-leadless pacemaker.

Nanostim™ (St. Jude Medical Inc., Saint Paul, MN, USA; now Abbott Medical Inc. Abbott Park, IL, USA) was the first self-contained intracardiac pacemaker to be implanted in ahuman patient. Atotal of 1423 Nanostim devices were implanted worldwide between 2013 and 2016 and three clinical trials were initiated. Although the device was recalled in 2016 owing to rare but serious battery failures, the concept of leadless pacing has gained widespread acceptance and is expanding beyond the initial single-chamber devices to dual-chamber systems, biventricular pacing, and combinations with defibrillators. This review describes the design, results from initial clinical trials, and long-term experiences with Nanostim. It discusses the lessons learned from the pioneering device's successes and shortcomings, many of which are valid for leadless pacemakers in general. This article also considers the Nanostim experience in comparison with the early years of clinical use for other pioneering device therapies. Important questions include how to minimize the risk for short-term complications by appropriate operator training and evaluation of suitable patients, what the long-term performance tells us about safety, as well as the necessity and feasibility of device explantation.

Perioperative management of cardiac rhythm assist devices in ambulatory surgery and nonoperating room anesthesia.

Patients with cardiac implantable electronic devices (CIEDs) frequently undergo various surgical procedures and in the past perioperative management involved only placing magnet over the device. New programming features, development of implantable cardiac defibrillator (ICD), cardiac resynchronization therapy, and increasing complexity of the operating room equipment have led to new sources of electromagnetic interference (EMI). A comprehensive understanding of the CIED is necessary to provide a timely and optimal care to the patients. Technological advancements and direct implantation of the transvenous implantable cardiac defibrillators into the heart have led to less clear lines between the pacemakers and the ICD. Subcutaneous ICD as well as the leadless transcatheter deployed intracardiac pacemaker development has complicated the issue further. Rapidly developing technologies and increasing number of patients with these devices coming for noncardiac surgeries necessitate continuous education of the anesthesia team regarding perioperative management of such devices.

136-38: Physical activity detection of a total intracardiac leadless pacemaker with 3-axis accelerometer

136-38: Physical activity detection of a total intracardiac leadless pacemaker with 3-axis accelerometer

Intra-cardiac pacemaker infection: Surgical management and outcome

BackgroundPacemaker infections are rare, but serious complications of pacemaker therapy. The generator pocket, the pacing leads, or both may be involved. MethodsWe report 21 patients with infected pacemaker systems. All had infected pacemaker and pacemaker leads with tricuspid valve endocarditis. Pacemaker systems were completely removed in all patients. Extracorporeal circulation with beating heart was employed for the explantation of infected pacing leads, generator and removal of vegetations on tricuspid valve and repair of tricuspid valve. Then a permanent epicardial pacemaker lead was inserted. ResultsNo complications occurred in patients with localized generator pocket infections. Two patients with infected leads, who were preoperatively already in a serious clinical condition, died of septic shock in the early postoperative period. No recurrent infections were observed. ConclusionExplantation of the complete pacemaker system has proved a reliable method to eradicate infection. Complications were rare, except in patients who present lately in a critically ill condition and septic shock.

Cardiovascular Developments in 2015

One of the studies was on the optimal hemoglobin threshold for blood transfusion decision after cardiac surgery. Observational studies suggest that the use of red blood cell concentrate transfusions are associated with higher rates of mortality and complications, leading a constant pursuit of more restrictive protocols. The TITRe2 study was a randomized trial with 2003 patients undergoing elective cardiac surgery, in which hemoglobin reached levels lower than 9 g/dL and have been tested using two different strategies: (1) liberal transfusions of red blood cell concentrates or (2) a more restrictive strategy in which the threshold for transfusion was reduced to 7.5 g/dL1. The restrictive strategy was not better than the more liberal one regarding health costs or morbidity. Although it is a secondary outcome of the study, the fact that the more restrictive strategy was associated with higher mortality was worth of note, but it was not clear whether increased mortality was due to anemia. As pointed out in editorial comments, the study shows the need to develop institutional protocols to manage postoperative anemia2. Another significant development refers to the development of artificial pacemaker fully implanted in the heart. Each year, more than one million people receive pacemaker implants, but the rate of pacemaker-related complications is 10.0%. A substantial number of adverse events are related to the electrodes. An intracardiac pacemaker implanted percutaneously in the heart with no electrodes has been developed. The device was tested on 526 consecutive patients with successful implantation in 90.0% of the cases and an adverse event rate of 6.7% in six months. The cardiac perforation rate was 1.3%3. The new device is a great potential advancement and opens up new development possibilities for artificial cardiac pacing that should improve its characteristics and test it in new situations.

Infectious endocarditis detected by PET/CT in a patient with a prosthetic knee infection: Case report and review of the literature

We report a case illustrating the potential use of 18F-fluorodeoxyglucose positron emission tomography combined with computed tomography (PET/CT) for the diagnosis of infective endocarditis (IE) in an 84-y-old woman who had a history of chronic left knee osteitis and a mitral cardiac valve bioprosthesis replacement and a pacemaker. She developed a polymicrobial knee infection 15 days after her total knee replacement. Transoesophageal echocardiography showed a new mitral regurgitation, but no vegetation or abscess. PET/CT showed hypermetabolic hyperactivity around the mitral cardiac valve prosthesis and the intracardiac pacemaker leads. We found 17 case reports and 2 case series of IE in which PET/CT showed encouraging results for the detection of IE. PET/CT may be used in patients with a suspicion of IE who do not have echocardiographic evidence of IE. It may also be useful for identifying the portal of entry of an infection and for identifying secondary foci (mycotic aneurysm).

EComment. Surgical complications of permanent cardiac pacemaker insertion

We read with interest the manuscript by Wu and Chen and we would like to comment on the surgical complications of intracardiac pacemaker implantation [1]. The use of permanent pacemakers (PPM) and implantable cardioverter-defibrillators (ICD) is increasing due to the expansion of indications and aging of the population. As a consequence, cardiologists and cardiothoracic surgeons have to deal with a broad spectrum of complications, which are sometimes under-estimated and life-threatening. The surgical complications of PPM and ICD may occur during the immediate or early post-operative period and can be related to venous access process (pneumothorax, hemothorax, air embolism, haematoma, arterial puncture, wound healing problems, infection, pain), to the pacemaker lead (cardiac perforation, tamponade, malposition or dislodgement of the lead), or to the generator device. In addition, other complicationed that may occur during the late post-operative period are related to infections, thrombosis, endocarditis, pulmonary embolism, superior vena cava (SVC) syndrome (due to thrombus formation and/or fibrosis of the pacing wires within the SVC) and pericarditis [2-5]. Ostovan and Aslani have reported on the successful treatment of massive pulmonary air embolism during a PPM implantation with air suctioning by the guide catheter inserted into main pulmonary artery via the left femoral vein. Treatment for air embolisms includes oxygen treatment, haemodynamic support and prevention of further air entry in the systemic circulation. The left lateral decubitus position can prevent the air obstruction of the pulmonary outflow tract (air can be moved toward the right ventricular apex) [2]. Aggarwal et al. found no difference in the incidence of intraoperative and early postoperative complications (up to two months after implantation) between single and dual chamber pacing systems [3]. Sohail et al., in their retrospective review of 189 patients with pacemaker related infections, found out that the most common clinical presentations were generator pocket infection (69%) and device-related endocarditis (23%). The leading pathogens were Coagulase-negative Staphylococci and Staphylococcus aureus, in 42% and 29% of cases, respectively. There was a broad spectrum of related complications such us septic arthritis, sternal or vetebral or femoral osteomyelitis, and abscesses in lung, spleen, liver, brain and perinephric area. Twenty-two (11.6%) patients had thrombosis of the subclavian vein or superior vena cava and 6 of them developed clinical manifestations of pulmonary embolism. Ninety-eight percent of patients underwent complete device removal combined with antibiotic treatment and 96% of patients were treated successfully [4]. Nineteen patients had lead extraction via a median sternotomy and the rest underwent percutaneous lead extraction. Interventional complications were more common in patients with a history of multiple device-related procedures and were related to tricuspid valve failure, laceration of subclavian vein, hemothorax, haematoma, fracture of lead tip, ventriculotomy and bleeding [4]. Right atrial thrombosis and pulmonary embolism are infrequent complications (0.6%-3.5%) and its therapeutic modalities include anticoagulation, thrombolysis and or surgery [5]. In conclusion, the knowledge of all potential complications of the PPM/ICD and its multidisciplinary approach is very important for its prevention and definitive treatment. Conflict of interest: none declared

Gerbode-Type Defect Induced by Catheter Ablation of the Atrioventricular Node

A 72-year-old man with a history of dilated cardiomyopathy, prosthetic aortic valve, biventricular intracardiac pacemaker, and permanent atrial fibrillation presented with uncontrolled ventricular response from atrial fibrillation despite pharmacological therapy. He underwent radiofrequency (RF) catheter ablation of the atrioventricular (AV) node to achieve optimal biventricular pacing. AV node ablation was performed via the right femoral vein with a 4-mm tip ablation catheter (EPT, Boston-Scientific) positioned at the AV node just proximal to the His bundle region. RF energy was applied at this site for 60 seconds (55°C) resulting in complete heart block with an escape rhythm of 32 bpm. The next day he was discharged uneventfully. An echocardiogram at 5 months follow-up showed a left ventricular to right atrial (LV-RA) shunt across the membranous septum immediately above the tricuspid valve (online-only Data Supplement Movies I and II and Figure 1A and 1B). This LV-RA shunt (Gerbode-type defect) had a 76-mm Hg gradient across the defect (Figure 1C). Left ventricular ejection fraction was depressed (25% to 30%) and the right ventricle was mildly to moderately dilated. The mechanical aortic prosthetic valve functioned normally with a mean gradient of 17 mm Hg. Review of …

The Metamorphosis of the Thrombus After Thrombolytic Therapy

A 55-year-old male was admitted to the cardiology department because of progressive fatigue and exercise intolerance. The patient’s previous history included a dual-chamber pacemaker implantation 7 years before as a result of bradycardia-tachycardia syndrome and inferior myocardial infarction 6 years ago, which resulted in left ventricular systolic dysfunction (ejection fraction of 30% on echocardiography and chronic total occlusion of the right coronary artery on coronary angiography). As a result of paroxysmal atrial fibrillation, the pacemaker had previously been switched to …

Diagnosis

Diagnosis

Integration of the Heart Rhythmogenesis Levels: Heart Rhythm Generator in the Brain

We propose that along with the intracardiac pacemaker, a generator of cardiac rhythm exists in the central nervous system - in the efferent structures of the cardiovascular center of the medullar oblongata. Signals in the medulla oblongata arise as a result of the hierarchic interaction of the brain structures. Neural signals originating there in the form of bursts of impulses conduct to the heart along the vagus nerves and after interaction with cardiac pacemaker structures, cause generation of the cardiac pulse in exact accordance with the frequency of neural bursts. The intrinsic cardiac rhythm generator (the sinus node) is a life-sustaining factor that maintains the heart pumping function when the central nervous system is in a stage of deep inhibition, (e.g., under anesthesia or during unconsciousness). The brain generator is the factor that provides heart adaptive reactions in behaving organism. The integration of the two levels of rhythmogenesis in the brain and heart provides reliability and functional perfection of the cardiac rhythm generation system in the whole organism.

Hierarchy of the heart rhythmogenesis levels is a factor in increasing the reliability of cardiac activity

Along with the existence of an intracardiac pacemaker a generator of cardiac rhythm exists in the central nervous system - in the efferent structures of the cardiovascular center of the medullar oblongata. Neural signals originating there in the form of bursts of impulses conduct to the heart along the vagus nerves and after interaction with cardiac pacemaker structures cause generation of the cardiac pulse in exact accordance with the frequency of the neural bursts. That the intrinsic cardiac rhythm generator is a life-sustaining factor that maintains the heart pumping function when the central nervous system is in a stage of deep inhibition. The brain generator is the factor that provides the heart with adaptive reactions to changes in the environment. The hierarchy of the two duplicating levels of rhythmogenesis provides reliability and functional perfection of the cardiac rhythm generation system in the whole organism.

INTEGRATION OF THE HEART RHYTHMOGENESIS LEVELS: HEART RHYTHM GENERATOR IN THE BRAIN

We propose that along with the intracardiac pacemaker, a generator of cardiac rhythm exists in the central nervous system--in the efferent structures of the cardiovascular center of the medullar oblongata. Signals in the medulla oblongata arise as a result of the hierarchic interaction of the brain structures. Neural signals originating there in the form of bursts of impulses conduct to the heart along the vagus nerves and after interaction with cardiac pacemaker structures, cause generation of the cardiac pulse in exact accordance with the frequency of "neural bursts". The intrinsic cardiac rhythm generator (the sinus node) is a life-sustaining factor that maintains the heart pumping function when the central nervous system is in a stage of deep inhibition, (e.g., under anesthesia or during unconsciousness). The brain generator is the factor that provides heart adaptive reactions in behaving organism. The integration of the two levels of rhythmogenesis in the brain and heart provides reliability and functional perfection of the cardiac rhythm generation system in the whole organism.