Predictors of atrial fibrillation detection and features of recurrent strokes in patients after cryptogenic stroke.

BACKGROUND AND PURPOSE: Use of implantable cardiac monitors (ICMs) has increased diagnosis of atrial fibrillation (AF) in cryptogenic stroke (CS) patients. Identifying AF predictors may enhance the yield of AF detection. Recurrent strokes after CS are not well described. We aimed to assess the predictors for AF detection and the characteristics of recurrent strokes in patients after CS. METHODS: We reviewed electronic medical records of CS patients who were admitted between February 2014 and September 2017 and underwent ICM placement with minimum one-year follow-up. Patient demographics, stroke characteristics, pre-defined risk factors as well as recurrent strokes were compared between patients with and without AF detection. RESULTS: 389 patients with median follow-up of 548 days were studied. AF was detected in 102 patients (26.2%). Age (per decade increase, OR 2.10, CI 1.64-2.68, with vs. without AF) and left atrium diameter (per 5 mm increase, OR 1.91, CI 1.33-2.74) were identified as AF predictors. Intracranial large vessel stenosis >50% irrelevant to the index strokes was associated with AF detection within 30 days (OR 0.24, CI 0.09-0.69, >30 vs. <30 days). Recurrent strokes occurred in 14% patients with median follow-up about 2.5 years. Topography of these strokes resembled embolic pattern and was comparable between patients with and without AF. Among recurrent strokes in patients with AF, the median time to AF detection was much shorter (90 vs. 251 days), and the median time to first stroke recurrence was much longer (422 vs. 76 days) in patients whose strokes recurred after AF detection than those before AF detection. CONCLUSIONS: Older age and enlarged left atrium are predictors for AF detection in CS patients. Intracranial atherosclerosis is more prevalent in patients with early AF detection within 30 days. Recurrent strokes follow the embolic pattern, and early AF detection could delay the stroke recurrence.

Single-shot terahertz time-domain spectroscopy in pulsed high magnetic fields.

We have developed a single-shot terahertz time-domain spectrometer to perform optical-pump/terahertz-probe experiments in pulsed, high magnetic fields up to 30 T. The single-shot detection scheme for measuring a terahertz waveform incorporates a reflective echelon to create time-delayed beamlets across the intensity profile of the optical gate beam before it spatially and temporally overlaps with the terahertz radiation in a ZnTe detection crystal. After imaging the gate beam onto a camera, we can retrieve the terahertz time-domain waveform by analyzing the resulting image. To demonstrate the utility of our technique, we measured cyclotron resonance absorption of optically excited carriers in the terahertz frequency range in intrinsic silicon at high magnetic fields, with results that agree well with published values.

Health care utilization in a nurse practitioner-led atrial fibrillation clinic.

BACKGROUND: Atrial fibrillation (AF) is the most common cardiac arrhythmia and is emerging in prevalence with an increasingly aging population. The complex nature of the disease and its association with significant morbidity and mortality has resulted in a call for a new integrative, multidisciplinary approach to AF management. PURPOSE: Determine if the use of a nurse practitioner (NP)-led AF clinic (NPAFC) can improve care for patients. METHODOLOGY: An NPAFC was designed to serve as an independent clinic for standardizing patient care and improving access to care. Baseline patient demographics, care pathway, and interventions were characterized in clinic. Primary outcomes were hospitalizations and emergency department (ER) visits, before and after clinic implementation. RESULTS: Overall, 1,442 patients were enrolled in the AF clinic between January 2016 and June 2018. The mean age at the first AF clinic visit was 68.7 ± 12.6 years, 54% were male, and the mean body mass index was 31 ± 7 kg/m2. Among the patients, 45.2% had paroxysmal AF, 43.6% persistent AF, and 5.5% permanent AF. With an average of 3 ± 3 clinic visits per patient, the number of patients with ≥1 hospitalization decreased by 78% after clinic implementation. Similarly, the number of patients with ≥1 ER visit decreased by 79%, and 22.7% of patients avoided at least one ER visit. CONCLUSIONS: The number of patients with ≥1 hospitalization or ≥1ER visit decreased within two years after the implementation of an NPAFC. IMPLICATIONS: Implementation of an NP-led AF clinic in the United States may reduce hospitalizations and ER visits if implemented in an integrative model.

Performance of first pacemaker to use smart device app for remote monitoring.

BACKGROUND: High adherence to remote monitoring (RM) in pacemaker (PM) patients improves outcomes; however, adherence remains suboptimal. Bluetooth low-energy (BLE) technology in newer-generation PMs enables communication directly with patient-owned smart devices using an app without a bedside console. OBJECTIVE: To evaluate the success rate of scheduled RM transmissions using the app compared to other RM methods. METHODS: The BlueSync Field Evaluation was a prospective, international cohort evaluation, measuring the success rate of scheduled RM transmissions using a BLE PM or cardiac resynchronization therapy PM coupled with the MyCareLink Heart app. App transmission success was compared to 3 historical "control" groups from the Medtronic de-identified CareLink database: (1) PM patients with manual communication using a wand with a bedside console (PM manual transmission), (2) PM patients with wireless automatic communication with the bedside console (PM wireless); (3) defibrillator patients with similar automatic communication (defibrillator wireless). RESULTS: Among 245 patients enrolled (age 64.8±15.6 years, 58.4% men), 953 transmissions were scheduled through 12 months, of which 902 (94.6%) were successfully completed. In comparison, transmission success rates were 56.3% for PM manual transmission patients, 77.0% for PM wireless patients, and 87.1% for defibrillator wireless patients. Transmission success with the app was superior across matched cohorts based on age, sex, and device type (single vs dual vs triple chamber). CONCLUSION: The success rate of scheduled RM transmissions was higher among patients using the smart device app compared to patients using traditional RM using bedside consoles. This novel technology may improve patient engagement and adherence to RM.

Idiopathic ventricular tachycardia originating from the left ventricle near the His bundle.

A 62-year-old man with idiopathic ventricular tachycardia (VT) exhibiting left bundle branch block and left inferior axis QRS morphology with a Qr in lead III underwent electrophysiological testing. Successful ablation was achieved in the left ventricle (LV) at a site with an excellent pace map, adjacent to the His bundle electrogram recording site. At that site, the sequence of the ventricular electrogram and late potential recorded during sinus rhythm reversed during spontaneous premature ventricular contractions with the same QRS morphology as the VT. This case shows that VT can arise from the LV ostium adjacent to the membranous septum.

Atrial tachycardia originating from the cavo-tricuspid isthmus may exhibit narrow P waves.

An 83-year-old man underwent electrophysiological testing for focal atrial tachycardia (AT) exhibiting narrow P waves with negative deflections in the inferior leads. Catheter ablation at the cavo-tricuspid isthmus (CTI) successfully eliminated the AT. The propagation map during AT and pacing study from the successful ablation site demonstrated that the atrial activation throughout the CTI did not produce significant P wave deflections. Consequently, during AT, the left atrial activation time determined the P wave duration. This case demonstrates that AT originating from the CTI may exhibit narrow P waves which can be misinterpreted as AT originating from the inter-atrial septum.

Detection of atrial fibrillation using an implantable loop recorder following cryptogenic stroke: implications for post-stroke electrocardiographic monitoring.

PURPOSE: Approximately 10-40% of strokes are cryptogenic (CS). Long-term electrocardiographic (ECG) monitoring has been recommended in these patients to search for atrial fibrillation (AF). An unresolved issue is whether ambulatory ECG (AECG) monitoring should be performed first, followed by an implantable loop recorder (ILR) if AECG monitoring is non-diagnostic, or whether long-term ECG monitoring should be initiated using ILRs from the onset. The purpose of this study was to assess, using an ILR, AF incidence in the first month after CS. METHODS: We enrolled consecutive CS patients referred for an ILR. All patients were monitored via in-hospital continuous telemetry from admission until the ILR (Medtronic [Minneapolis, MN] LINQ™) was implanted. The duration and overall burden of all AF episodes ≥ 2 min was determined. RESULTS: The cohort included 343 patients (68 ± 11 years, CHA2DS2-VASc 3.5 ± 1.7). The time between stroke and ILR was 3.7 ± 1.5 days. During the first 30 days, only 18 (5%) patients had AF. All episodes were paroxysmal, lasting from 2 min to 67 h and 24 min. The median AF burden was 0.85% (IQR 0.52, 10.75). During 1 year of follow-up, 67 (21%) patients had AF. CONCLUSION: The likelihood of AF detection by an ILR in the first month post-CS is low. Thus, the diagnostic yield of 30 days of AECG monitoring is likely to be limited. These data suggest a rationale for proceeding directly to ILR implantation prior to hospital discharge in CS patients, as many have AF detected during longer follow-up.

Idiopathic focal ventricular arrhythmias originating from the anterior papillary muscle in the left ventricle.

INTRODUCTION: Focal ventricular arrhythmias (VAs) have been reported to arise from the posterior papillary muscle in the left ventricle (LV). We report a distinct subgroup of idiopathic VAs arising from the anterior papillary muscle (APM) in the LV. METHODS AND RESULTS: We studied 432 consecutive patients undergoing catheter ablation for VAs based on a focal mechanism. Six patients were identified with ventricular tachycardia (VT, n = 1) or premature ventricular contractions (PVCs, n = 5) with the earliest site of ventricular activation localized to the base (n = 3) or middle portion (n = 3) of the LV APM. No Purkinje potentials were recorded at the ablation site during sinus rhythm or the VAs. All patients had a normal baseline electrocardiogram and normal LV systolic function. The VAs exhibited a right bundle branch block (RBBB) and right inferior axis (RIA) QRS morphology in all patients. Oral verapamil and/or Na(+) channel blockers failed to control the VAs in 4 patients. VT was not inducible by programmed electrical stimulation in any of the patients. In 4 patients, radiofrequency current with an irrigated or conventional 8-mm-tip ablation catheter was required to achieve a lasting success. Two patients had recurrent PVCs after a conventional radiofrequency ablation with a 4-mm-tip ablation catheter had initially suppressed the arrhythmia. CONCLUSIONS: VAs may arise from the base or middle portion of the APM and are characterized by an RBBB and RIA QRS morphology and focal mechanism. Catheter ablation of APM VAs is typically challenging, and creation of a deep radiofrequency lesion may be necessary for long-term success.

Ventricular fibrillation induced by a radiofrequency energy delivery for idiopathic premature ventricular contractions arising from the left ventricular anterior papillary muscle.

A 73-year-old man with idiopathic premature ventricular contractions (PVCs) underwent electrophysiological testing. Left ventricular activation mapping revealed a focal mechanism of the PVCs with the earliest activation on the anterior papillary muscle (APM). Irrigated radiofrequency (RF) current delivered at that site induced a cluster of non-sustained ventricular tachycardia episodes with the same QRS morphology as the PVCs, followed by ventricular fibrillation (VF). The APM might have served as an abnormal automatic trigger and driver for the VF occurrence. Ventricular fibrillation may occur as a complication during RF catheter ablation of papillary muscle ventricular arrhythmias even if the clinical arrhythmia is limited to PVCs.

An assessment of Oxford Nanopore sequencing for human gut metagenome profiling: A pilot study of head and neck cancer patients.

Gut metagenome profiling using the Oxford Nanopore Technologies (ONT) sequencer was assessed in a pilot-sized study of 10 subjects. The taxonomic abundance of gut microbiota derived from ONT was comparable with Illumina Technology (IT) for the high-abundance species. IT better detected low-abundance species through amplification, when material was limited.

Biventricular ICD implantation using the iliofemoral approach: providing CRT to patients with occluded superior venous access.

A 32-year-old woman with a history of nonischemic dilated cardiomyopathy, left bundle branch block, left ventricular ejection fraction of 0.15, and New York Heart Association Class III congestive heart failure, despite optimal medical treatment, was referred for cardiac resynchronization therapy with implantation of an implantable cardioverter defibrillator. The patient had prior chemotherapy for non-Hodgkin's lymphoma and was shown to have chronic total occlusion of the superior vena cava (SVC) by magnetic resonance imaging. Cardiac resynchronization was accomplished with an iliofemoral approach without complications resulting in marked clinical improvement. We conclude that the iliofemoral approach allows transvenous implantation of cardiac resynchronization therapy in patients with superior vena cava occlusion.

The transmural activation sequence in porcine and canine left ventricle is markedly different during long-duration ventricular fibrillation.

BACKGROUND: Humans are more similar in transmural Purkinje and cardiac ion channel distributions to dogs than pigs. The Purkinje network in pigs is transmural but confined to the endocardium in dogs. Little is known about intramural activation during long-duration ventricular fibrillation (LDVF) given these differences. We tested the hypothesis that the transmural activation sequence is similar in sinus rhythm (SR) and LDVF in dogs as well as pigs, but different between species. METHODS AND RESULTS: In six pigs and seven dogs, 50-60 plunge needles (six electrodes, 2-mm spacing) were placed throughout the left ventricle. Unipolar recordings were made for >10 minutes of LDVF. SR and LDVF activation times were grouped into waves by linking activations along each needle. Origin (earliest activation) and propagation direction were determined for each wave. The mean wave origin was significantly more endocardial in dogs than pigs for SR and 1 through 10 minutes of LDVF. Predominant propagation direction in LDVF and SR was endocardial to epicardial in dogs, but the opposite or equal in both directions in pigs. Fastest activation rate was epicardial in pigs, but endocardial in dogs with an increasing endocardial-to-epicardial activation rate gradient as LDVF progressed in dogs but not pigs. CONCLUSIONS: The transmural activation sequence in SR and LDVF is markedly different between pigs and dogs. These differences may be related to differences in Purkinje fiber and ion channel distributions and suggest that dogs are a better model for investigating activation sequences during LDVF, given the similarities with humans.

Transmural and endocardial Purkinje activation in pigs before local myocardial activation after defibrillation shocks.

BACKGROUND: Earliest recorded postshock myocardial activations in pigs originate in the subepicardium of the apex and lateral free wall of the left ventricle (LV) 30-90 ms after the shock. OBJECTIVE: The purpose of this study was to determine whether the Purkinje system is a candidate for the source of postshock activations by performing endocardial and transmural postshock activation mapping. METHODS: In five pigs, 32 plunge needles with 12 electrodes (1-mm spacing) were inserted into the LV apex and lateral free wall. Up to 70 plunge needles with six electrodes (2-mm spacing) were spread throughout the remainder of the LV, while 9-12 plunge needles with four electrodes (2-mm spacing) were inserted into the right ventricle. A basket catheter with 32 bipolar recording sites was inserted into the LV. Defibrillation-threshold (DFT)-level shocks were delivered during 10 episodes of electrically induced ventricular fibrillation. Electrograms of postshock activation cycles were analyzed for Purkinje and myocardial activations. RESULTS: Purkinje activations were recorded before local myocardial activation in 9% of basket electrograms and in 15% of plunge needles during the first postshock activation cycle. Purkinje activations were identified during the first and subsequent several postshock activation cycles in at least one basket and one needle electrogram in 96% and 98% of defibrillation episodes, respectively. CONCLUSIONS: The Purkinje system is active during the early postshock activation cycles after DFT-level shocks. Further studies are required to determine whether activation initiates in the Purkinje system or whether it is activated by the myocardium or by Purkinje-myocardial junctional cells.

The role of plasma fatty acid composition in endogenous glucose production in patients with type 2 diabetes mellitus.

Hepatic insulin resistance and increased endogenous glucose production (EGP) are associated with increased plasma free fatty acids (FFA). However, the contribution of FFA composition to the regulation of EGP is not known. Six obese nondiabetic subjects and 6 patients with type 2 diabetes mellitus (DM2) were studied after an overnight and a 3-day fast. Plasma insulin concentrations after an overnight fast were similar in the DM2 and nondiabetic patients (88.8 +/- 26.4 v 57.6 +/- 12.6 pmol/L, not significant [NS]) despite increased plasma glucose (9.9 +/- 1.8 v 5.1 +/- 0.1 mmol/L, P <.01) and EGP (510.3 +/- 77.7 v 298.3 +/- 18.3 micromol x m(-2) x min(-1), P <.05) in the patients with DM2. Absolute rates of gluconeogenesis using the heavy water method were also increased in the patients with DM2 (346.8 +/- 74.9 v 198.8 +/- 16.4 micromol x m(-2). min(-1), P <.05). No differences were observed in plasma polyunsaturated fatty acids (PUFA) between the diabetic and nondiabetic subjects. However, total saturated fatty acid (SFA) concentrations (350 +/- 37.4 v 230.9 +/- 33.3 micromol/L, P <.02) were significantly increased in the diabetic subjects. Rates of EGP were correlated with total plasma FFA concentration (r =.71, P <.01) and the concentration of SFA (r =.71, P <.01), but not monounsaturated fatty acids or PUFA. Rates of gluconeogenesis were also correlated with plasma FFA (r =.64, P <.05) and SFA (r =.67, P <.05). We observed no relationship between EGP and either total FFA or fatty acid composition after a 3-day fast. We conclude that increases in EGP are associated with concentrations of plasma SFA after an overnight fast.

Objective measurement of erythema in psoriasis using digital color photography with color calibration.

Traditional metrics for evaluating the severity of psoriasis are highly subjective, which complicates efforts to identify effective treatments in clinical trials. We propose a method for the objective measurement of the psoriasis severity parameter of erythema (redness). This procedure is standardized for different camera systems and lighting environments through the usage of a color card with predetermined color values in order to calibrate the images. Quantitative measures based on the digital color images are shown to correlate well with subjective assessment of psoriasis severity collected using a standard numerical scale by a panel of dermatologists. Additionally, the color calibration process is shown to improve results.