Validation of a Deep Learning Algorithm for Continuous, Real-Time Detection of Atrial Fibrillation Using a Wrist-Worn Device in an Ambulatory Environment.

BACKGROUND: Wearable devices may be useful for identification, quantification and characterization, and management of atrial fibrillation (AF). To date, consumer wrist-worn devices for AF detection using photoplethysmography-based algorithms perform only periodic checks when the user is stationary and are US Food and Drug Administration cleared for prediagnostic uses without intended use for clinical decision-making. There is an unmet need for medical-grade diagnostic wrist-worn devices that provide long-term, continuous AF monitoring. METHODS AND RESULTS: We evaluated the performance of a wrist-worn device with lead-I ECG and continuous photoplethysmography (Verily Study Watch) and photoplethysmography-based convolutional neural network for AF detection and burden estimation in a prospective multicenter study that enrolled 117 patients with paroxysmal AF. A 14-day continuous ECG monitor (Zio XT) served as the reference device to evaluate algorithm sensitivity and specificity for detection of AF in 15-minute intervals. A total of 91 857 intervals were contributed by 111 subjects with evaluable reference and test data (18.3 h/d median watch wear time). The watch was 96.1% sensitive (95% CI, 92.7%-98.0%) and 98.1% specific (95% CI, 97.2%-99.1%) for interval-level AF detection. Photoplethysmography-derived AF burden estimation was highly correlated with the reference device burden (R2=0.986) with a mean difference of 0.8% (95% limits of agreement, -6.6% to 8.2%). CONCLUSIONS: Continuous monitoring using a photoplethysmography-based convolutional neural network incorporated in a wrist-worn device has clinical-grade performance for AF detection and burden estimation. These findings suggest that monitoring can be performed with wrist-worn wearables for diagnosis and clinical management of AF. REGISTRATION INFORMATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT04546763.

Implant efficiency and clinical performance of Aveir™ VR and Micra™ VR leadless pacemaker: A multicenter comparative analysis of 67 patients.

INTRODUCTION: Leadless pacemaker (LP) is a novel pacemaker that has been proven to be effective and safe; however, the majority of LPs in previous reports were the Medtronic Micra™ VR LP. We aim to evaluate the implant efficiency and clinical performance of the Aveir™ VR LP compared to the Micra™ VR LP. METHOD: We performed a retrospective analysis in two healthcare systems (Sparrow Hospital and Ascension Health System, Michigan) in patients implanted with LPs between January 1, 2018, and April 1, 2022. The parameters were collected at implantation, 3 months and 6 months. RESULTS: A total of 67 patients were included in the study. The Micra™ VR group had shorter time in the electrophysiology lab (41 ± 12 vs. 55 ± 11.5 min, p = .008) and shorter fluoroscopic time (6.5 ± 2.2 vs. 11.5 ± 4.5 min, p < .001) compared to the Aveir™ VR group. The Aveir™ VR group had a significantly higher implant pacing threshold compared to the Micra™ VR group (0.74 ± 0.34 mA vs. 0.5 ± 0.18 mA at pulse width 0.4 ms, p < .001), but no difference was found at 3 months and 6 months. There was no significant difference in the R-wave sensing and impedance and pacing percentage at implantation, 3 months, and 6 months. Complications of the procedure were rare. The mean projected longevity of the Aveir™ VR group was longer than the Micra™ VR group (18.8 ± 4.3 vs. 7.7 ± 0.75 years, p < .001). CONCLUSION: Implantation of the Aveir™ VR required longer laboratory and fluoroscopic time, but showed longer longevity at 6 months follow-up, compare to the Micra™ VR. Complications and lead dislodgement are rare.

Assessing Correlation Between Thoracic Impedance and Remotely Monitored Pulmonary Artery Pressure in Chronic Systolic Heart Failure.

Background: Heart failure (HF) readmission continues to be a major health problem. Monitoring pulmonary artery pressure (PAP) and thoracic impedance (TI) are the two modalities utilized for early identification of decompensation in HF patients. We aimed to assess the correlation between these two modalities in patients who simultaneously had both the devices. Methods: Patients with history of New York Heart Association class III systolic HF with a pre-implanted intracardiac defibrillator (ICD) capable of monitoring TI and pre-implanted CardioMEMs™ remote HF monitoring device were included. Hemodynamic data including TI and PAPs were measured at baseline and then weekly. Weekly percentage change was then calculated as: Weekly percentage change = (week 2 - week1)/week 1 × 100. Variability between the methods was expressed by Bland-Altman analysis. Significance was determined as a P-value < 0.05. Results: Nine patients met the inclusion criteria. There was no significant correlation between the assessed weekly percentage changes in pulmonary artery diastolic pressure (PAdP) and TI measurements (r = -0.180, P = 0.065). Using Bland-Altman analytic methods, both methods had no significant difference in agreement (0.011±0.094%, P = 0.215). With the linear regression model applied for Bland-Altman analysis, the two methods appeared to have proportional bias without agreement (unstandardized beta-coefficient of 1.91, t 22.9, P ≤ 0.001). Conclusion: Our study demonstrated that variations exist between measurement of PAdP and TI; however, there is no significant correlation between weekly variations between them.

Implantable Cardioverter-defibrillator Magnetic Interference by the iPhone 12: Is It Clinically Significant?

The iPhone 12 series (Apple, Inc., Cupertino, CA, USA) contains a circular array of magnets around a central charging coil (compatible with "Magsafe" technology). The device was recently reported to have magnetic interference with implantable cardioverter-defibrillators (ICDs). We sought to test the electromagnetic interference of the iPhone 12 in inhibiting life-saving therapies of ICDs in clinical settings. After obtaining written informed consent, an iPhone 12 was placed over the device generators of 17 patients in the ICD clinic. Device interrogation was performed immediately before and after placing the iPhone over the ICD generator to evaluate for any inhibition of device therapies. To emulate a real-world scenario, the iPhone 12 was not placed directly over the skin above the device generator but instead was positioned over the patients' clothes. None of the device interrogations revealed interruption of device therapies due to the iPhone. We concluded that, despite the iPhone having shown in vitro interference of ICD functioning, its effects are not clinically relevant in vivo. Larger studies need to be performed to confirm this finding and guide safety recommendations regarding the use of iPhones containing magnets by patients with implanted ICDs.

Patients' and family members' views on pacemaker reuse: An international survey.

INTRODUCTION: The reuse of cardiac implantable electronic devices may help increase access to these therapies in low- and middle-income countries (LMICs). No published data exist regarding the views of patients and family members in LMICs regarding this practice. METHODS AND RESULTS: An article questionnaire eliciting attitudes regarding pacemaker reuse was administered to ambulatory adult patients and patients' family members at outpatient clinics at Centro Nacional Cardiologia in Managua, Nicaragua, Indus Hospital in Karachi, Pakistan, Hospital Carlos Andrade Marín, and Hospital Eugenio Espejo in Quito, Ecuador, and American University of Beirut Medical Center in Beirut, Lebanon. There were 945 responses (Nicaragua - 100; Pakistan - 493; Ecuador - 252; and Lebanon - 100). A majority of respondents agreed or strongly agreed that they would be willing to accept a reused pacemaker if risks were similar to a new device (707, 75%), if there were a higher risk of device failure compared with a new device (584, 70%), or if there were a higher risk of infection compared to a new device (458, 56%). A large majority would be willing to donate their own pacemaker at the time of their death (884, 96%) or the device of a family member (805, 93%). Respondents who were unable to afford a new device were more likely to be willing to accept a reused device (79% vs. 63%, p < .001). CONCLUSIONS: Patients and their family members support the concept of pacemaker reuse for patients who cannot afford new devices.

Frost-free zone on macrotextured surfaces.

Numerous studies have focused on designing functional surfaces that delay frost formation or reduce ice adhesion. However, solutions to the scientific challenges of developing antiicing surfaces remain elusive because of degradation such as mechanical wearing. Inspired by the discontinuous frost pattern on natural leaves, here we report findings on the condensation frosting process on surfaces with serrated structures on the millimeter scale, which is distinct from that on a conventional planar surface with microscale/nanoscale textures. Dropwise condensation, during the first stage of frosting, is enhanced on the peaks and suppressed in the valleys, causing frost to initiate from the peaks, regardless of surface chemistry. The condensed droplets in the valley are then evaporated due to the lower vapor pressure of ice compared with water, resulting in a frost-free zone in the valley, which resists frost propagation even on superhydrophilic surfaces. The dependence of the frost-free areal fraction on the geometric parameters and the ambient conditions is elucidated by both numerical simulations based on steady-state diffusion and an analytical method with an understanding of boundary conditions independent of surface chemistry. We envision that this study would provide a unified framework to design surfaces that can spatially control frost formation, crystal growth, diffusion-controlled growth of biominerals, and material deposition over a broad range of applications.

Onset time of fog collection.

Fog collection is a promising solution to the worldwide water scarcity problem and is also of vital importance to industrial processes, such as recapturing water in cooling towers and mist elimination. To date, numerous studies have investigated the fog collection rate, a parameter that denotes the average performance over a long period of time. However, the initial period (referred to as onset time) between the start of the fog-laden flow and the actual collection of the captured liquid (a delay in time caused by droplet growth to a critical weight that exceeds droplet-surface retention force) has not been systematically understood. A longer onset time may result in a more serious clogging issue that deteriorates the collection rate and, hence, understanding this phenomenon is important. Here, we study how the onset time is determined by the capture and transport of fog using individual, vertical wires with various surface wettabilities and diameters, under different wind speeds. This approach allows us to derive a scaling law that correlates the onset time with the fog capture process and droplet-surface retention force, governed by aerodynamics and interfacial phenomena, respectively. In particular, the onset time decreases with an increasing rate of fog capture or a decreasing droplet-surface retention force. This study introduces an important aspect in the evaluation of fog collection and provides insights for the optimal design of fog collectors and mist eliminators.

Fatal esophageal-pericardial fistula as a complication of radiofrequency catheter ablation.

The clinical role of catheter ablation using radiofrequency or cryothermal energy has become an important therapy in the management of patients with recurrent or persistent tachyarrhythmia that is refractory to medical therapy. It is regarded as a safe and reliable procedure and is performed routinely in health care facilities across the country. Like all procedures, there are associated risks and benefits. Development of an esophageal-atrial fistula is a rare but often-fatal complication of radiofrequency ablation. It is the second most frequent cause of death caused by the procedure, with mortality rates in excess of 70%. Death usually occurs as a result of cerebral or myocardial air embolism, endocarditis, massive gastrointestinal bleeding, and/or septic shock. Electrophysiologists have instituted a number of safeguard techniques to diminish the risk of developing esophageal-atrial fistula. Despite these measurements, instances of fistulous development still occur. Herein, we report a case of a 74-year-old male who presented with chest pain secondary to esophageal-pericardial fistula 19 days after pulmonary vein isolation using radiofrequency energy for atrial fibrillation in order to illustrate the clinical variability and diagnostic challenges associated with this dreaded gastrointestinal complication.

The safety and efficacy of electroanatomical mapping (EAM)-guided device implantation.

BACKGROUND: The conventional method of device implantation requires fluoroscopic guidance. With the guidance of three-dimensional (3-D) navigation systems, devices can be implanted with minimal use of fluoroscopy. To date, this technique has been reported in several case reports in young, pregnant patients. However, this technique has not been widely utilized by electrophysiologists, despite offering several benefits, including reduced radiation exposure for the patient and the operator. METHODS: In this study, we evaluated 18 patients who successfully underwent device implantation with limited use of fluoroscopy under the guidance of the EnSite Precision 3-D mapping navigation system (Abbott, St. Paul, MN, USA). In most of the patients, the total fluoroscopy time was 1 s, accounted by a single postprocedural frame to insure appropriate lead placement. RESULTS: A total of 19 leads were implanted in 18 patients (14 male, four female) using the electroanatomical mapping (EAM)-guided technique. A total of 19 leads were implanted in 15 patients (10 male, five female) using the conventional method. The average length of stay was 1.20 days in the EAM group compared to 1.47 days in the conventional group (P = .10). Majority of the devices implanted in both groups were single-chamber implantable cardiac defibrillators (VVI ICD, Abbott) implanted for cardiomyopathy with left ventricular ejection fraction persistently below 35%, including 88% (16/18) in the EAM group compared to 73% (11/15) in the conventional group. No periprocedural or immediate postprocedure complications were reported in either group. Device parameters, including impedance, capture time, and capture voltage, showed no significant difference in either group. Total radiation time and radiation dose were markedly lower in the EAM-guided implantation group. CONCLUSIONS: In patients who meet appropriate criteria for device implantation, the use of EAM system offers a safe, practical, efficacious alternative method to device implantation, with significant reduction in radiation time and dose.

Atrial-Esophageal Fistula After Catheter Ablation: Diagnosing and Managing a Rare Complication of a Common Procedure.

BACKGROUND Atrial fibrillation is considered the most common cardiac arrhythmias in the United States with rate and rhythm control strategies traditionally used for management. If patients are intolerant to class I or class III anti-arrhythmic medications, catheter ablation may be used as a rhythm control strategy. As catheter ablation becomes more commonplace, so too do the procedure-related complications, which include tamponade, total arterio-venous fistula, pulmonary vein stenosis, and atrial-esophageal fistula. CASE REPORT A 67-year-old male underwent catheter ablation for atrial fibrillation and subsequently presented with complaints of fever and chills. Initial workup for a source of infection included a computed tomography (CT) scan and transesophageal echocardiogram which did not reveal any abnormalities. Antibiotic therapy was initiated, and multiple CT scans were performed; eventually patient was found to have an atrial-esophageal fistula, secondary to thermal injury. The patient underwent thoracotomy and full thickness necrosis of the posterior left atrium and pericardium near the base of the left inferior pulmonary vein was visualized, with a roughly nickel sized orifice, which was repaired. The patient had an uneventful recovery and was doing well on follow-up. CONCLUSIONS Atrial-esophageal fistula is a rare but lethal complication of atrial fibrillation ablation. While imaging modalities have improved and can detect the condition, they can also yield ambivalent findings which can challenge patient care. It is important for clinicians to maintain a heightened awareness of this complication in post-ablation patients and utilize clinical history and not rely solely on imaging to diagnose and treat this complication.

Assessing the Risks Associated with MRI in Patients with a Pacemaker or Defibrillator.

BACKGROUND: The presence of a cardiovascular implantable electronic device has long been a contraindication for the performance of magnetic resonance imaging (MRI). We established a prospective registry to determine the risks associated with MRI at a magnetic field strength of 1.5 tesla for patients who had a pacemaker or implantable cardioverter-defibrillator (ICD) that was "non-MRI-conditional" (i.e., not approved by the Food and Drug Administration for MRI scanning). METHODS: Patients in the registry were referred for clinically indicated nonthoracic MRI at a field strength of 1.5 tesla. Devices were interrogated before and after MRI with the use of a standardized protocol and were appropriately reprogrammed before the scanning. The primary end points were death, generator or lead failure, induced arrhythmia, loss of capture, or electrical reset during the scanning. The secondary end points were changes in device settings. RESULTS: MRI was performed in 1000 cases in which patients had a pacemaker and in 500 cases in which patients had an ICD. No deaths, lead failures, losses of capture, or ventricular arrhythmias occurred during MRI. One ICD generator could not be interrogated after MRI and required immediate replacement; the device had not been appropriately programmed per protocol before the MRI. We observed six cases of self-terminating atrial fibrillation or flutter and six cases of partial electrical reset. Changes in lead impedance, pacing threshold, battery voltage, and P-wave and R-wave amplitude exceeded prespecified thresholds in a small number of cases. Repeat MRI was not associated with an increase in adverse events. CONCLUSIONS: In this study, device or lead failure did not occur in any patient with a non-MRI-conditional pacemaker or ICD who underwent clinically indicated nonthoracic MRI at 1.5 tesla, was appropriately screened, and had the device reprogrammed in accordance with the prespecified protocol. (Funded by St. Jude Medical and others; MagnaSafe ClinicalTrials.gov number, NCT00907361 .).

Cannabis induced asystole.

Cannabis or marijuana is the most used recreational, and until recently illegal, drug in the United States. Although cannabis has medicinal use, its consumption has been linked to motor vehicle accidents in dose dependent fashion. Marijuana and other cannabinoids produce a multitude of effects on the human body that may result in these motor vehicle accidents. Some of the effects that marijuana has been known to cause include altered sensorium, diminished reflexes, and increased vagal tone. We present a case of cannabis induced asystole from hypervagotonia.

Flecainide-induced Torsades de Pointes: Case Report and Review of Literature.

Several antiarrhythmic drugs are prone to cause QT interval prolongation and torsades de pointes (TDP). Predisposing risk factors include congenital channelopathies, severe bradycardia, drugs, and hypokalemia. Individual genetic variation and drug metabolism exaggerate susceptibility to adverse reactions. These proarrhythmic effects create a deficit in the repolarization reserve and prolong action potential duration, resulting in early afterdepolarizations, which promote a reentry circuit. Flecainide, a class IC drug, also exhibits inhibitory actions on the K(+) channels, causing QT interval prolongation. We identified six cases of flecainide-induced TDP in the literature. Most patients had other predisposing factors. Bradycardia was present in all cases. Our case demonstrates two arrhythmias caused by flecainide: atrial flutter with 1:1 atrioventricular conduction and TDP. Both arrhythmias developed in the absence of hypokalemia, with the use of other drugs that prolong QT interval, or genetic predisposition. Therefore, this is purely a drug effect. This case report illustrates a rare but serious proarrhythmic property of flecainide observed particularly in women.

Timing for pacing after acquired conduction disease in the setting of endocarditis.

A 53-year-old gentleman with a history of a mechanical aortic valve presented to the emergency department complaining of a sudden right-sided abdominal pain. He was found to have atrioventricular dissociation on his initial electrocardiogram and his blood cultures grew Streptococcus viridans. The suspicion for endocarditis with periaortic abscess was high so a transthoracic echocardiogram was performed and showed a mass in the left ventricular outflow tract. For better visualization, a transesophageal echocardiogram was recommended and revealed a bileaflet mechanical aortic valve with perivalvular abscess and valvular vegetation as well as severe eccentric paravalvular aortic regurgitation. After sterilization, the patient underwent a successful surgery. Postoperatively, he remained in complete heart block and a permanent pacemaker placement was performed after complete sterilization. He tolerated the procedure well and was discharged home in a stable condition. Perivalvular abscess is one of the most common cardiac complications of infective endocarditis and is associated with an increased risk of mortality. It is imperative to have appropriate treatment guidelines established. However, because of the relative nature of the disease process and the acuity at which intervention needs to be done, a true assessment of the duration of antibiotic therapy prior to surgical intervention, timing of pacemaker placement, and the type of pacemaker is controversial.

Cardiac sarcoidosis presenting as constrictive pericarditis.

In patients with cardiac sarcoidosis, the sarcoid granulomas usually involve the myocardium or endocardium. The disease typically presents as heart failure with ventricular arrhythmias, conduction disturbances, or both. Constrictive pericarditis has rarely been described in patients with sarcoidosis: we found only 2 reports of this association. We report the case of a 57-year-old man who presented with clinical and hemodynamic features of constrictive pericarditis, of unclear cause. He was admitted for treatment of recurrent pleural effusion. After a complicated hospital course, he underwent pericardiectomy. His clinical and hemodynamic conditions improved substantially, and he was discharged from the hospital in good condition. The pathologic findings, the patient's clinical course, and his response to pericardiectomy led to our diagnosis of cardiac sarcoidosis presenting as constrictive pericarditis. In addition to the patient's case, we discuss the nature and diagnostic challenges of cardiac sarcoidosis. Increased awareness of this disease is necessary for its early detection, appropriate management, and potential cure.

Caveolae-mediated endocytosis of conjugated polymer nanoparticles.

Understanding the cellular entry pathways of synthetic biomaterials is highly important to improve overall labeling and delivery efficiency. Herein, cellular entry mechanisms of conjugated polymer nanoparticles (CPNs) are presented. CPNs are intrinsic fluorescent materials used for various biological applications. While CPNs cause no toxicity, decreased CPN uptake is observed from cancer cells pretreated with genistein, which is an inhibitor of caveolae-mediated endocytosis (CvME). CvME is further confirmed by high co-localization with caveolin-1 proteins found in the caveolae and caveosomes. Excellent photophysical properties, non-toxicity, and non-destructive delivery pathways support that CPNs are promising multifunctional carriers minimizing degradation of contents during delivery.