SciCombinator

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Concept: Artificial pacemaker

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There have been concerns that Electromagnetic security systems such as walk-through metal detectors (WTMDs) can potentially cause electromagnetic interference (EMI) in certain active medical devices including implantable cardiac pacemakers and implantable neurostimulators. Incidents of EMI between WTMDs and active medical devices also known as personal medical electronic devices (PMED) continue to be reported. This paper reports on emission measurements of sample WTMDs and testing of 20 PMEDs in a WTMD simulation system.

Concepts: Engineering, Measuring instruments, Implantable cardioverter-defibrillator, Airport security, Electromagnetic interference, Artificial pacemaker

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A flexible single crystalline PMN-PT piezoelectric energy harvester is demonstrated to achieve a self-powered artificial cardiac pacemaker. The energy harvesting device generates a short-circuit current of 0.223 mA and an open-circuit voltage of 8.2 V, which are enough to meet the standard for not only charging commercial batteries but also stimulating heart without an external power source.

Concepts: Electrical conduction system of the heart, Sinoatrial node, Cardiac pacemaker, Cardiology, Piezoelectricity, Volt, Energy harvesting, Artificial pacemaker

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BACKGROUND: The risks of sports participation for implantable cardioverter-defibrillator (ICD) patients are unknown. METHODS AND RESULTS: Athletes with ICDs (age, 10-60 years) participating in organized (n=328) or high-risk (n=44) sports were recruited. Sports-related and clinical data were obtained by phone interview and medical records. Follow-up occurred every 6 months. ICD shock data and clinical outcomes were adjudicated by 2 electrophysiologists. Median age was 33 years (89 subjects <20 years of age); 33% were female. Sixty were competitive athletes (varsity/junior varsity/traveling team). A pre-ICD history of ventricular arrhythmia was present in 42%. Running, basketball, and soccer were the most common sports. Over a median 31-month (interquartile range, 21-46 months) follow-up, there were no occurrences of either primary end point-death or resuscitated arrest or arrhythmia- or shock-related injury-during sports. There were 49 shocks in 37 participants (10% of study population) during competition/practice, 39 shocks in 29 participants (8%) during other physical activity, and 33 shocks in 24 participants (6%) at rest. In 8 ventricular arrhythmia episodes (device defined), multiple shocks were received: 1 at rest, 4 during competition/practice, and 3 during other physical activity. Ultimately, the ICD terminated all episodes. Freedom from lead malfunction was 97% at 5 years (from implantation) and 90% at 10 years. CONCLUSIONS: Many athletes with ICDs can engage in vigorous and competitive sports without physical injury or failure to terminate the arrhythmia despite the occurrence of both inappropriate and appropriate shocks. These data provide a basis for more informed physician and patient decision making in terms of sports participation for athletes with ICDs.

Concepts: Participation, Decision making, Decision theory, Interquartile range, Artificial pacemaker, Cardiac electrophysiology, Ventricular fibrillation, Implantable cardioverter-defibrillator

7

To the Editor: The LEADLESS II study (Sept. 17 issue)(1) reports the safety and efficacy of a leadless, self-contained, percutaneously implanted pacemaker that is an innovative example of miniaturization. The effect of cremation on this pacemaker was not studied. Given the rising number of cremations being performed worldwide, the potential hazard associated with the cremation of persons who have this pacemaker is a concern.(2),(3) The battery in the leadless pacemaker is a lithium carbon monofluoride-polycarbon fluoride device, which has a high density of energy.(4) It is hypothesized that the greater the energy density of a battery, the greater the . . .

Concepts: Capacitor, Rechargeable battery, Implantable cardioverter-defibrillator, Cardiac pacemaker, Energy, Artificial pacemaker, Battery, Lithium battery

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Contemporary pacemakers (PMs) are powered by primary batteries with a limited energy storing capacity. PM replacements due to battery depletion are common, unpleasant and bear the risk of complications. Batteryless PMs harvesting energy inside the body may overcome these limitations.

Concepts: Primary cell, Death, Cardiology, Battery, Cardiac electrophysiology, Lithium battery, Cardiac pacemaker, Artificial pacemaker

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Irreversible degeneration of the cardiac conduction system is a common disease that can cause activity intolerance, fainting, and death. While electronic pacemakers provide effective treatment, alternative approaches are needed when long-term indwelling hardware is undesirable. Biological pacemakers comprise electrically active cells that functionally integrate with the heart. Recent findings on cardiac pacemaker cells (PCs) within the sinoatrial node (SAN), along with developments in stem cell technology, have opened a new era in biological pacing. Recent experiments that have derived PC-like cells from non-PCs have brought the field closer than ever before to biological pacemakers that can faithfully recapitulate SAN activity. In this review, I discuss these approaches in the context of SAN biology and address the potential for clinical translation.

Concepts: Myocardial infarction, Artificial pacemaker, Action potential, Cardiology, Heart, Sinoatrial node, Electrical conduction system of the heart, Cardiac pacemaker

5

Pacemaker leads, which connect the chest-wall generator of a pacemaker to the pacing electrode in the heart, are the “Achilles' heel” of pacing and defibrillation systems. Over time, they wear out, which often necessitates their risky removal and replacement. In addition, transvenous leads provide a portal into the vascular space, which increases the risk of infection. Patients with traditional pacemakers and defibrillators are also susceptible to hematomas and pocket infections in the chest wall where the generators lie. Thus, a self-contained leadless pacemaker that can be placed directly into the heart is an appealing prospect. Reports of two recent nonrandomized, . . .

Concepts: Fibrillation, Implantable cardioverter-defibrillator, Asystole, Risk, Transcutaneous pacing, Cardiac electrophysiology, Defibrillation, Artificial pacemaker

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The US Food and Drug Administration (FDA) evaluates high-risk medical devices such as cardiac implantable electronic devices (CIEDs), including pacemakers, implantable cardioverter-defibrillators, and cardiac resynchronization therapy devices, via the premarket approval (PMA) process, during which manufacturers submit clinical data demonstrating safety and effectiveness. Subsequent changes to approved high-risk devices are implemented via “supplements,” which may not require additional clinical testing.

Concepts: Pharmaceutical drug, Electronics, Medicine, Artificial pacemaker, Medical device, Implantable cardioverter-defibrillator, Food and Drug Administration, Federal Food, Drug, and Cosmetic Act

4

We aimed to determine how age-associated changes in mechanisms extrinsic and intrinsic to pacemaker cells relate to basal beating interval variability (BIV) reduction in vivo. Beating intervals (BIs) were measured in aged (23-25 months) and adult (3-4 months) C57BL/6 male mice (i) via ECG in vivo during light anesthesia in the basal state, or in the presence of 0.5 mg mL(-1) atropine + 1 mg mL(-1) propranolol (in vivo intrinsic conditions), and (ii) via a surface electrogram, in intact isolated pacemaker tissue. BIV was quantified in both time and frequency domains using linear and nonlinear indices. Although the average basal BI did not significantly change with age under intrinsic conditions in vivo and in the intact isolated pacemaker tissue, the average BI was prolonged in advanced age. In vivo basal BIV indices were found to be reduced with age, but this reduction diminished in the intrinsic state. However, in pacemaker tissue BIV indices increased in advanced age vs. adults. In the isolated pacemaker tissue, the sensitivity of the average BI and BIV in response to autonomic receptor stimulation or activation of mechanisms intrinsic to pacemaker cells by broad-spectrum phosphodiesterase inhibition declined in advanced age. Thus, changes in mechanisms intrinsic to pacemaker cells increase the average BIs and BIV in the mice of advanced age. Autonomic neural input to pacemaker tissue compensates for failure of molecular intrinsic mechanisms to preserve average BI. But this compensation reduces the BIV due to both the imbalance of autonomic neural input to the pacemaker cells and altered pacemaker cell responses to neural input.

Concepts: Brain, Cardiac electrophysiology, Ageing, Gerontology, Artificial pacemaker, Death, Cardiology, Cardiac pacemaker