Low-Cost Fetal Magnetocardiography: A Comparison of Superconducting Quantum Interference Device and Optically Pumped Magnetometers.

Background Fetal magnetocardiography (fMCG) is a highly effective technique for evaluation of fetuses with life-threatening arrhythmia, but its dissemination has been constrained by the high cost and complexity of Superconducting Quantum Interference Device (SQUID) instrumentation. Optically pumped magnetometers (OPMs) are a promising new technology that can replace SQUIDs for many applications. This study compares the performance of an fMCG system, utilizing OPMs operating in a person-sized magnetic shield, to that of a conventional fMCG system, utilizing SQUID magnetometers operating in a magnetically shielded room. Methods and Results fMCG recordings were made in 24 subjects using the SQUID system with the mother lying supine in a magnetically shielded room and the OPM system with the mother lying prone in a person-sized, cylindrical shield. Signal-to-noise ratios of the OPM and SQUID recordings were not statistically different and were adequate for diagnostic purposes with both technologies. Although the environmental noise was higher using the small open-ended shield, this was offset by the higher signal amplitude achieved with prone positioning, which reduced the distance between the fetus and sensors and improved patient comfort. In several subjects, fMCG provided a differential diagnosis that was more precise and/or definitive than was possible with echocardiography alone. Conclusions The OPM-based system was portable, improved patient comfort, and performed as well as the SQUID-based system at a small fraction of the cost. Electrophysiological assessment of fetal rhythm is now practical and will have a major impact on management of fetuses with long QT syndrome and other life-threatening arrhythmias.

Early Detection and Treatment of Atrial Arrhythmias Alleviates the Arrhythmic Burden in Paced Patients: The SETAM Study.

BACKGROUND: Remote monitoring (RM) can remotely detect atrial tachyarrhythmias (ATAs). The benefit of RM compared to conventional follow-up in the detection and management of ATA was assessed in recipients of dual-chamber pacemakers. METHODS: The multicenter randomized SETAM study enrolled 595 patients in sinus rhythm with a CHA2 DS2 -VASc score ≥2, without ATA history and untreated with antiarrhythmics and antithrombotics, randomly assigned to RM (RM-ON; n = 291) versus ambulatory follow-up (RM-OFF; n = 304) during 12.8 ± 3.3 months. ATA occurrence, burden, and management were analyzed together with adverse clinical events. RESULTS: Patients were 79 ± 8 years old, 63% men, with a CHA2 DS2 -VASc score of 3.7± 1.2. ATA were detected in 83 patients (28%) in the RM-ON versus 66 (22%) in the RM-OFF group (P = 0.06). The median time between the pacemaker implantation and the first treated ATA was 114 days [44; 241] in the RM-ON versus 224 days [67; 366] in the RM-OFF group (hazard ratio [HR] = 0.56; 95% confidence interval [CI]: 0.37-0.86; P = 0.01). Therapies for ATA were initiated in 92 patients and the time to treatment of ATA was shortened by 44% in the RM-ON group (HR = 0.565; 95% CI: 0.37-0.86; P = 0.01). Over the last 4 months of follow-up, the mean ATA burden was alleviated by 4 hours/day (18%) in the RM-ON group. The rate of adverse clinical events was similar in both groups. CONCLUSION: Remotely monitored patients were diagnosed and treated earlier for ATA, and subsequently had a lower ATA burden.

[Implantable loop recorder BioMonitor 2 (Biotronik)]. / Implantierbarer Loop-Rekorder BioMonitor 2 (Fa. Biotronik).

The implantable loop recorder BioMonitor 2 is available with an emphasis on syncope and one on detection of atrial tachycardias. The BioMonitor 2 can be easily implanted. The BioMonitor 2 pilot study showed a high and over time stable signal and the telemetric performance was above average.

Accurate ECG diagnosis of atrial tachyarrhythmias using quantitative analysis: a prospective diagnostic and cost-effectiveness study.

UNLABELLED: Quantitative ECG Analysis. INTRODUCTION: Optimal atrial tachyarrhythmia management is facilitated by accurate electrocardiogram interpretation, yet typical atrial flutter (AFl) may present without sawtooth F-waves or RR regularity, and atrial fibrillation (AF) may be difficult to separate from atypical AFl or rapid focal atrial tachycardia (AT). We analyzed whether improved diagnostic accuracy using a validated analysis tool significantly impacts costs and patient care. METHODS AND RESULTS: We performed a prospective, blinded, multicenter study using a novel quantitative computerized algorithm to identify atrial tachyarrhythmia mechanism from the surface ECG in patients referred for electrophysiology study (EPS). In 122 consecutive patients (age 60 ± 12 years) referred for EPS, 91 sustained atrial tachyarrhythmias were studied. ECGs were also interpreted by 9 physicians from 3 specialties for comparison and to allow healthcare system modeling. Diagnostic accuracy was compared to the diagnosis at EPS. A Markov model was used to estimate the impact of improved arrhythmia diagnosis. We found 13% of typical AFl ECGs had neither sawtooth flutter waves nor RR regularity, and were misdiagnosed by the majority of clinicians (0/6 correctly diagnosed by consensus visual interpretation) but correctly by quantitative analysis in 83% (5/6, P = 0.03). AF diagnosis was also improved through use of the algorithm (92%) versus visual interpretation (primary care: 76%, P < 0.01). Economically, we found that these improvements in diagnostic accuracy resulted in an average cost-savings of $1,303 and 0.007 quality-adjusted-life-years per patient. CONCLUSIONS: Typical AFl and AF are frequently misdiagnosed using visual criteria. Quantitative analysis improves diagnostic accuracy and results in improved healthcare costs and patient outcomes.

Validation of coronary sinus activation pattern during left atrial appendage pacing for beat-to-beat assessment of mitral isthmus conduction/block.

INTRODUCTION: Mitral isthmus (MI) ablation for treatment of perimitral flutter is often performed during atrial fibrillation (AF) ablation but is technically challenging. Traditional assessment of MI conduction by left atrial activation mapping while pacing from either side of the line is time-consuming, and cannot be performed during ongoing ablation. Analysis of the coronary sinus (CS) activation pattern during left atrial appendage (LAA) pacing has been proposed as a simpler technique for evaluating MI conduction, enabling beat-to-beat assessment of conduction during ablation procedures and prompt identification of conduction block. METHODS: MI conduction was evaluated in 40 patients undergoing MI ablation using both: ((i) endocardial activation mapping and other standard techniques, and (ii) CS activation pattern during LAA pacing (change from distal-to-proximal activation to proximal-to-distal taken to signify the onset of MI block). RESULTS: CS activation sequence was used to assess conduction in 39 of 40 patients (unable to advance CS catheter distally in one case). MI block was achieved in 36 of 39 cases. The mean MI conduction time (LAA to distal CS) was 92.9 +/- 25.9 ms prior to ablation and 178.4 +/- 59.9 ms after MI block was confirmed. The mean step-out in conduction time at point of block was 80.8 +/- 40.6 ms. In all individuals in whom CS activation indicated block, there was concordance with endocardial activation, differential pacing and, where detectable, presence of widely split double potentials. CS lesions were required to achieve block in 24 of 36 (67%) successful cases. Radiofrequency application time and procedure time to achieve MI block were 10.8 +/- 6.0 minutes and 21.1 +/- 15.3 minutes, respectively.

[Clinical experiences with cooled radiofrequency ablation of ectopic atrial tachycardia employing an electroanatomic mapping system]. / Klinische Erfahrungen mit der gekühlten Radiofrequenzablation ektoper atrialer Tachykardien unter Einsatz eines elektroanatomischen Mappingsystems.

Due to its variable origin success for ablation of ectopic atrial tachycardia (EAT) has been difficult to achieve using conventional mapping and ablation strategies. In contrast, no information in the literature is available about the use of a nonfluoroscopic, 3-dimensional electroanatomic mapping system (CARTO) combined with the cooled ablation technology creating deeper lesions in experimental studies compared to standard catheters. In 20 consecutive patients (15 female; age 52.5 +/- 15.4 years), a single focus responsible for clinical EAT has been mapped. Twelve EATs were located in the right atrium, whereas 8 foci were left sided including 3 origins within a pulmonary vein (PV). Due to the reported development of PV stenosis in the ablative treatment of focal atrial fibrillation, direct ablation applied inside the PV was avoided. Instead, PV-disconnection achieved by the use of a Lasso trade mark catheter in 1 case and by circumferential ablation around the PV in 2 other patients was preferred. In 2 patients, ablation was not attempted because of an origin located directly in the area of the atrioventricular node. In another case, CARTO mapping was stopped due to persistent mechanical termination of the tachycardia with no possibility of reinduction. In the latter, ablation was performed in sinus rhythm at the earliest mapped site before terminating. Three weeks later another episode of EAT was noted in this patient. In the remaining 17 cases, ablation was associated with acute success and no recurrences of sustained tachycardia in all patients. Mean duration time was 192 +/- 53.3 min (right atrium 161 +/- 37.9 min; left atrium 229.6 +/- 46.2 min), and average fluoroscopic time was 22.8 +/- 9.7 min (right atrium 17.1 +/- 6.2 min; left atrium 29.8 +/- 8.9 min). There was no incidence of serious complications associated with this procedure. In conclusions, electroanatomical mapping including cooled ablation was a safe and feasible strategy in treating EATs. The benefit of this technique may imply the combination of both precise localization of the focus and effective applications of radiofrequency pulses, thereby minimizing acute failures or reablation. Due to the time consuming point by point data acquisition, the ability to generate precise maps demonstrating the earliest activation at their exact anatomical location can be limited by transient or persistent termination of the tachycardia.