Effectiveness of "Physician Prompt Clinical Decision Criteria" in Weaning Outcome Prediction for Neurocritical Patients.

Endotracheal intubation and invasive mechanical ventilation are fundamental components for the resuscitation of neurocritically ill patients to achieve various goals which include ensuring the protection of the airway, participating in tissue oxygen delivery and indirectly modulating cerebral vascular reactivity. The neurocritical patients demand special attention to their systemic involvement regarding weaning. Physician prompt clinical decision criteria (PPC) can play a better role in weaning of such patients. The aim of this study was to evaluate the effectiveness of 'Physician prompt clinical decision criteria' for successful weaning in neurocritical patients. This prospective observational study was conducted in the ICU, Department of Anaesthesia, Analgesia, Palliative & Intensive Care Medicine, Dhaka Medical College Hospital (DMCH), Dhaka, Bangladesh from March 2018 to April 2020. In total 100 neurocritical patients who fulfilled the inclusion criteria were taken as samples by informed written consent. The outcome was observed as successful weaning or as failed weaning. Finally, the existence of Standard extubation criteria (SEC) was compared with Physician prompt clinical decision criteria (PPC). Weaning was succeeded in 80.0% of patients and failed in 20.0% according to the Standard extubation criteria (SEC) while weaning was succeeded in 85.7% of patients and failed in 14.28% according to the Physician prompt clinical decision criteria (PPC). There were some differences in results but no significant differences were observed statistically between the groups in predicting the weaning outcome. Physician prompt clinical decision criteria were found to be 75.0% sensitive and specificity was 50.0%. Positive predictive value for Physician prompt clinical decision criteria was 85.70% with a Positive likelihood ratio for these criteria was 1.5 times. So, according to the study findings, accuracy of Physician prompt clinical decision criteria was 70.0%. According to the findings of this current study we can conclude that Physician prompt clinical decision criteria are an effective weaning readiness predictor in neurocritical patients.

Delivery of mutant huntingtin-lowering antisense oligonucleotides to the brain by intranasally administered apolipoprotein A-I nanodisks.

Lowering mutant huntingtin (mHTT) in the central nervous system (CNS) using antisense oligonucleotides (ASOs) is a promising approach currently being evaluated in clinical trials for Huntington disease (HD). However, the therapeutic potential of ASOs in HD patients is limited by their inability to cross the blood-brain barrier (BBB). In non-human primates, intrathecal infusion of ASOs results in limited brain distribution, with higher ASO concentrations in superficial regions and lower concentrations in deeper regions, such as the basal ganglia. To address the need for improved delivery of ASOs to the brain, we are evaluating the therapeutic potential of apolipoprotein A-I nanodisks (apoA-I NDs) as novel delivery vehicles for mHTT-lowering ASOs to the CNS after intranasal administration. Here, we have demonstrated the ability of apoA-I nanodisks to bypass the BBB after intranasal delivery in the BACHD model of HD. Following intranasal administration of apoA-I NDs, apoA-I protein levels were elevated along the rostral-caudal brain axis, with highest levels in the most rostral brain regions including the olfactory bulb and frontal cortex. Double-label immunohistochemistry indicates that both the apoA-I and ASO deposit in neurons. Most importantly, a single intranasal dose of apoA-I ASO-NDs significantly reduces mHTT levels in the brain regions most affected in HD, namely the cortex and striatum. This approach represents a novel non-invasive means for improving delivery and brain distribution of oligonucleotide therapies and enhancing likelihood of efficacy. Improved ASO delivery to the brain has widespread application for treatment of many other CNS disorders.

A computational study of the thortveitite structure of zinc pyrovanadate, Zn2V2O7, under pressure.

We performed a pressure-driven study of zinc pyrovanadate, Zn2V2O7, using the first-principles approach under the framework of density functional theory (DFT). Zn2V2O7 crystalizes in a monoclinic (α-phase) structure with the space group C2/c at ambient pressure. In comparison with the ambient phase, there are four different high-pressure phases, namely ß, γ, κ and δ, found at 0.7, 3.8, 4.8 and 5.3 GPa, respectively. The detailed crystallographic analysis as well as their structures is consistent with the theory and experiment reported in the literature. All phases including the ambient phase are mechanically stable, elastically anisotropic and malleable. The compressibility of the studied pyrovanadate is higher than that of the other meta- and pyrovanadates. The energy dispersion of these studied phases reveals that they are indirect band gap semiconductors with wide band gap energies. The band gap energies follow a reduced trend with pressure except the κ-phase. The effective masses for all of these studied phases were computed from their corresponding band structures. The values of energy gaps obtained from the band structures are almost similar to the optical band gap obtained from the optical absorption spectra, as estimated by the Wood-Tauc theory.

Generation of multiple obstruction-free channels for free space optical communication.

Multi-filament structures produced by vortical high-power femtosecond pulses propagating through clouds and fog can simultaneously clear two channels with cylindrical and annular profile. We present a method to achieve Free Space Optical (FSO) communications through such highly scattering media by propagating appropriately shaped laser modes through these channels. As a proof of concept, we implemented a Laguerre-Gaussian beam as information signal carrier to demonstrate transmission of 543-nm CW laser beam through a 1-m long cloud chamber using both channels. The low power of the information signal in this experiment allows considering applications in Earth-satellite FSO communication.

Hematological prognosticators in metastatic renal cell cancer treated with immune checkpoint inhibitors: a meta-analysis.

Aim: We aimed to assess the prognostic value of pretreatment hematological biomarkers in patients with metastatic renal cell carcinoma (mRCC) treated with immune checkpoint inhibitors (ICIs). Methods: PubMed, Web of Science and Scopus databases were searched for articles according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. Results: Fifteen studies comprising 1530 patients were eligible for meta-analysis. High levels of neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), C-reactive protein and lactate dehydrogenase were significantly associated with worse progression-free survival. High NLR and PLR were significantly associated with worse overall survival. Conclusion: High pretreatment NLR and PLR appear to be hematological prognostic factors of progression and overall mortality in mRCC patients treated with ICIs. These findings might help in the design of correlative biomarker studies to guide the clinical decision-making in the immune checkpoint inhibitor era.

Identifying the predictive/prognostic factors that can be applied to daily clinical practice is mandatory to facilitate the use of immune checkpoint inhibitors. Some pretreatment hematological markers used in daily clinical practice appear to be prognostic factors in metastatic renal cell carcinoma patients treated with immune checkpoint inhibitors. We believe that the findings of the present meta-analysis might help researchers to design prospective correlative biomarker studies to guide clinical decision-making in the immunotherapy era.

Impact of preoperative systemic immune-inflammation Index on oncologic outcomes in bladder cancer patients treated with radical cystectomy.

PURPOSE: To investigate the predictive and prognostic value of the preoperative systemic immune-inflammation index (SII) in patients undergoing radical cystectomy (RC) for clinically non-metastatic urothelial cancer of the bladder (UCB). METHODS: Overall, 4,335 patients were included, and the cohort was stratified in two groups according to SII using an optimal cut-off determined by the Youden index. Uni- and multivariable logistic and Cox regression analyses were performed, and the discriminatory ability by adding SII to a reference model based on available clinicopathologic variables was assessed by area under receiver operating characteristics curves (AUC) and concordance-indices. The additional clinical net-benefit was assessed using decision curve analysis (DCA). RESULTS: High SII was observed in 1879 (43%) patients. On multivariable preoperative logistic regression, high SII was associated with lymph node involvement (LNI; P = 0.004), pT3/4 disease (P <0.001), and non-organ confined disease (NOCD; P <0.001) with improvement of AUCs for predicting LNI (P = 0.01) and pT3/4 disease (P = 0.01). On multivariable Cox regression including preoperative available clinicopathologic values, high SII was associated with recurrence-free survival (P = 0.028), cancer-specific survival (P = 0.005), and overall survival (P = 0.006), without improvement of concordance-indices. On DCAs, the inclusion of SII did not meaningfully improve the net-benefit for clinical decision-making in all models. CONCLUSION: High preoperative SII is independently associated with pathologic features of aggressive disease and worse survival outcomes. However, it did not improve the discriminatory margin of a prediction model beyond established clinicopathologic features and failed to add clinical benefit for decision making. The implementation of SII as a part of a panel of biomarkers in future studies might improve decision-making.

Time-Averaged Wavefront Analysis Demonstrates Preferential Pathways of Atrial Fibrillation, Predicting Pulmonary Vein Isolation Acute Response.

Electrical activation during atrial fibrillation (AF) appears chaotic and disorganised, which impedes characterisation of the underlying substrate and treatment planning. While globally chaotic, there may be local preferential activation pathways that represent potential ablation targets. This study aimed to identify preferential activation pathways during AF and predict the acute ablation response when these are targeted by pulmonary vein isolation (PVI). In patients with persistent AF (n = 14), simultaneous biatrial contact mapping with basket catheters was performed pre-ablation and following each ablation strategy (PVI, roof, and mitral lines). Unipolar wavefront activation directions were averaged over 10 s to identify preferential activation pathways. Clinical cases were classified as responders or non-responders to PVI during the procedure. Clinical data were augmented with a virtual cohort of 100 models. In AF pre-ablation, pathways originated from the pulmonary vein (PV) antra in PVI responders (7/7) but not in PVI non-responders (6/6). We proposed a novel index that measured activation waves from the PV antra into the atrial body. This index was significantly higher in PVI responders than non-responders (clinical: 16.3 vs. 3.7%, p = 0.04; simulated: 21.1 vs. 14.1%, p = 0.02). Overall, this novel technique and proof of concept study demonstrated that preferential activation pathways exist during AF. Targeting patient-specific activation pathways that flowed from the PV antra to the left atrial body using PVI resulted in AF termination during the procedure. These PV activation flow pathways may correspond to the presence of drivers in the PV regions.

Treatment of Recalcitrant Nonunion of the Radius With Posterior Interosseous Bone Flap in Children.

BACKGROUND: Forearm nonunion is a rare condition in children, and its treatment is usually successful. However, nontraumatic nonunion can be resistant to treatment. Although the vascularized fibular bone graft has been frequently used for complex forearm nonunion, there is no consensus on the best treatment method. In this study, we aimed to investigate the outcome of the antegrade posterior interosseous bone flap (PIBF) in treating children with complex radius nonunion. METHODS: The participants consisted of 3 girls and 1 boy ranging from 31 months to 9 years of age. They were treated with PIBF surgery, and the nonunion of the radius was fixed with a plate or an external fixator. The nonunion was due to congenital pseudoarthrosis, osteogenesis imperfecta, or infantile osteomyelitis. All patients were evaluated for a clinical and radiologic union. RESULTS: The radiologic union was achieved 2 to 3 months after the surgery in all cases. The functional recovery of the elbow, forearm, and wrist was satisfactory except for 1 patient who experienced donor site fracture, and finally radioulnar synostosis accompanied by radial head dislocation. CONCLUSION: Because of the simplicity of its technique and short duration of surgery, PIBF can be a reliable and less-demanding alternative to vascularized fibular bone graft in the treatment of complex forearm nonunion in children. LEVEL OF EVIDENCE: Level IV.

Multidisciplinary Team Effort Results in Better Outcomes in Critically Ill Obstetric Patients Admitted in ICU.

Management of critically ill obstetric patients is a great challenge for the ICU team. The safety of both mother and fetus are of real concerns. Teamwork is essential for better outcome in obstetric patients in the ICU. A 26 years old female was admitted in Dhaka Medical College Hospital, Dhaka, Bangladesh on 18 August 2019 with 7 months pregnancy with brain tumor (later diagnosed as Gliosarcoma) and was managed surgically by left temporal craniotomy with excision of the tumor. The patient was shifted to the ICU due to repeated convulsions and need mechanical ventilator support. Later on, she was suffering from sepsis with pseudomonas in blood culture, grade IV pressure ulcer and electrolyte imbalance and needed tracheostomy for airway management. On 34th weeks of her pregnancy she developed antepartum hemorrhage with respiratory distress. Emergency LUCS was done and she delivered a LBW baby who was managed in NICU. Mother was managed in the ICU and later on both mother and child were discharge with good conditions. Multidisciplinary team work is vital for better management of critically ill obstetric patients.

The role of lymph node dissection in salvage radical prostatectomy for patients with radiation recurrent prostate cancer.

PURPOSE: To examine the effect of lymph node dissection on the outcomes of patients who underwent salvage radical prostatectomy (SRP). MATERIAL AND METHODS: We retrospectively reviewed data from radiation-recurrent patients with prostate cancer (PCa) who underwent SRP from 2000-2016. None of the patients had clinical lymph node involvement before SRP. The effect of the number of removed lymph nodes (RLNs) and the number of positive lymph nodes (PLNs) on biochemical recurrence (BCR)-free survival, metastases free survival, and overall survival (OS) was tested in multivariable Cox regression analyses. RESULTS: About 334 patients underwent SRP and pelvic lymph node dissection (PLND). Lymph node involvement was associated with increased risk of BCR (p < .001), metastasis (p < .001), and overall mortality (p = .006). In a multivariable Cox regression analysis, an increased number of RLNs significantly lowered the risk of BCR (hazard ratio [HR] 0.96, p = .01). In patients with positive lymph nodes, a higher number of RLNs and a lower number of PLNs were associated with improved freedom from BCR (HR 0.89, p = .001 and HR 1.34, p = .008, respectively). At a median follow-up of 23.9 months (interquartile range, 4.7-37.7), neither the number of RLNs nor the number of PLNs were associated with OS (p = .69 and p = .34, respectively). CONCLUSION: Pathologic lymph node involvement increased the risk of BCR, metastasis and overall mortality in radiation-recurrent PCa patients undergoing SRP. The risk of BCR decreased steadily with a higher number of RLNs during SRP. Further research is needed to support this conclusion and develop a precise therapeutic adjuvant strategy based on the number of RLNs and PLNs.

A genome-wide methylation study of body fat traits in the Norfolk Island isolate.

BACKGROUND AND AIMS: Natural variation in body fat is explained by both genetic and environmental effects. Epigenetic mechanisms such as DNA methylation can mediate these effects causing changes in gene expression leading to onset of obesity. Studies of genetic isolates have the potential to provide new epigenetic insights with advantages such as reduced genetic diversity and environmental exposures. METHODS AND RESULTS: This was an exploratory study of genome-wide DNA methylation in relation to body fat traits in 47 healthy adults from the genetic isolate of Norfolk Island. Quantitative body fat traits (body fat percentage, body mass index, hip circumference, waist circumference, waist-hip-ratio and weight) were carefully measured. DNA methylation data was obtained from peripheral blood using Illumina 450K arrays. Multi-trait analysis was performed using Principal Component Analysis (PCA). CpG by trait association testing was performed using stepwise linear regressions. Two components were identified that explained approximately 89% of the phenotypic variance. In total, 5 differential methylated positions (DMPs) were identified at genome-wide significance (P≤ 2.4 × 10-7), which mapped to GOT2-CDH8, LYSMD3, HIBADH, ADGRD1 and EBF4 genes. Gene set enrichment analysis of 848 genes containing suggestive DMPs (P≤ 1.0 × 10-4) implicated the Cadherin (28 genes, Padj = 6.76 × 10-7) and Wnt signaling pathways (38 genes, Padj = 7.78 × 10-6). CONCLUSION: This study provides new insights into the epigenetically influenced genes and pathways underlying body fat variation in a healthy cohort and provides targets for consideration in future studies of obesity risk.

Outcome of Stapled Hemorrhoidopexy: Experience of 90 Cases.

Hemorrhoidal disease is one of the commonest anorectal problems in worldwide. Stapled hemorrhoidopexy is the treatment choice due to less post-operative pain and early recovery. The aim of this study was to assess outcomes after Stapled hemorrhoidopexy (SH). This cross-sectional prospective study was performed in Shaheed Suhrawardy Medical College Hospital, Dhaka from January 2016 to December 2017. Ninety patients with symptomatic hemorrhoidal diseases were included in this study. Data collected in data collection sheet regarding demographic data, severity of symptoms, post-operative complains of patient and outcome of patients which were then analyzed. Total 90 patients were included in this study. Age ranged from 18-50 years. Male were 59(65.56%) and female were 31(34.44%). 2° hemorrhoids were 11(12.22%), 3° hemorrhoids were 63(70%), 4° hemorrhoids were 16(17.78%). Post-operative complications were mild pain 73(81.11%), moderate pain 13(14.45%), severe pain 4(4.44%), early bleeding 23(25.56%), retention of urine 16(17.78%), early urgency 15(16.67%), infection 4(4.44%), constipation 9(10%), late recurrence 4(4.44%). Outcomes of stapled hemorrhoidopexy were satisfactory in most patients. Early recovery, low complication rate, minimal post-operative pain was encountered in treatment of symptomatic hemorrhoids by stapled hemorrhoidopexy.

Serum soluble suppression of tumorigenicity-2 level associates with severity of pulmonary hypertension associated with uncorrected atrial septal defect.

Uncorrected atrial septal defect undergoes right ventricle chronic volume overload which may lead to pulmonary hypertension and Eisenmenger Syndrome. The soluble suppression of tumorigenicity-2 is a left ventricle strain biomarker; however, its role in right ventricle strain is unclear. This study aimed to investigate the implication of serum soluble suppression of tumorigenicity-2 in adult uncorrected atrial septal defect. This was a cross-sectional study. We enrolled 81 adult uncorrected secundum atrial septal defect patients. Clinical and hemodynamic data were collected. Serum samples were withdrawn from the pulmonary artery during right heart catheterization. Serum soluble suppression of tumorigenicity-2 and NT-proBNP levels were measured. Subjects were divided into three groups based on clinical and hemodynamic severity. The correlation of soluble suppression of tumorigenicity-2 with patients' data and comparison among groups were analyzed. A p value <0.05 was considered statistically significant. Results showed that, there were significant correlations between serum soluble suppression of tumorigenicity-2 and mean pulmonary artery pressure (r = 0.203, p = 0.035) and right ventricle end-diastolic diameter (r = 0.203, p <0.05). Median serum soluble suppression of tumorigenicity-2 level was incrementally increased from group I (atrial septal defect and no-pulmonary hypertension), group II (left-to-right atrial septal defect and pulmonary hypertension), to group III (Eisenmenger Syndrome): (17.4 ng/mL, 21.8 ng/mL, and 29.4 ng/mL, respectively). A post-hoc analysis showed that serum soluble suppression of tumorigenicity-2 level was significantly different between groups I and III (p = 0.01). Serum N terminal pro brain natriuretic peptide (NT-proBNP) level was consistently associated with worse clinical and hemodynamic parameters. No correlation was found between serum soluble suppression of tumorigenicity-2 and NT-proBNP level. In conclusion, serum soluble suppression of tumorigenicity-2 level had significant positive correlation with mean pulmonary artery pressure and right ventricle end-diastolic diameter in uncorrected secundum atrial septal defect patients. Higher serum soluble suppression of tumorigenicity-2 level was associated with the presence of pulmonary hypertension and Eisenmenger Syndrome in uncorrected secundum atrial septal defect patients.

COVID-19 Epidemic in Switzerland: Growth Prediction and Containment Strategy Using Artificial Intelligence and Big Data

Using a previously developed agent-based artificial intelligence simulation platform (EnerPol) coupled with Big Data, the evolution and containment of COVID-19 in Switzerland is examined. The EnerPol platform has been used in a broad range of case studies in different sectors in all of Europe, USA, Japan, South Korea and sub Saharan Africa over the last 10 years. In the present study, the entire Swiss population (8.57 million people), including cross-border commuters, and the entire Swiss public and private transport network that is simulated to assess transmission of the COVID-19 virus. The individual contacts within the population, and possible transmission pathways, are established from a simulation of daily activities that are calibrated with micro-census data. Various governmental interventions with regards to closures and social distancing are also implemented. The epidemiology of the COVID-19 virus is based on publicly available statistical data and adapted to Swiss demographics. The predictions estimate that between 22 February and 11 April 2020, there will be 720 deaths from 83300 COVID-19 cases, and 73300 will have recovered; our preliminary variability in these estimates is about 21% over the aforementioned period. In the absence of governmental intervention, 42.7% of the Swiss population would have been infected by 25 April 2020 compared to our prediction of a 1% infection over this time period, saving thousands of lives. It is argued that future scenarios regarding relaxation of the lockdown should be carefully simulated, as by 19 April 2020, there will still remain a substantial number of infected individuals, who could retrigger a second spread of COVID-19. Through the use of a digital tool, such as Enerpol, to evaluate in a data-driven manner the impacts of various policy scenarios, the most effective measures to mitigate a spread of COVID-19 can be devised while we await the deployment of large-scale vaccination for the population globally. By tailoring the spatio-temporal characteristics of the spread to match the capacity of local healthcare facilities, appropriate logistic needs can be determined, in order not to overwhelm the health care services across the country.

Rooting behaviour and soil properties in different bamboo species of Western Himalayan Foothills, India.

Due to extensive root system, connected rhizome bamboos are considered suitable for improving soil properties within a short period, though most of the claims are anecdotal and need to be supported with quantified data. The study evaluates seven bamboo species viz., Bambusa balcooa, Bambusa bambos, Bambusa vulgaris, Bambusa nutans, Dendrocalamus hamiltonii, Dendrocalamus stocksii and Dendrocalamus strictus for their rooting pattern and impact on soil health properties. Coarse and fine root intensity was maximum in B. vulgaris. Coarse root biomass ranged from 0.6 kg m-3 in B. nutans to 2.0 kg m-3 in B. vulgaris and B. bambos. Fine root biomass ranged from 1.1 kg m-3 in B. nutans to 4.5 kg m-3 in D. hamiltonii. Contribution of fine roots in terms of intensity and biomass was much higher than coarse roots. Fine root biomass showed declining trend with increase in soil depth in all the species. During sixth year, the litter fall ranged from 8.1 Mg ha-1 in D. stocksii to 12.4 Mg ha-1 in D. hamiltonii. Among soil physical properties significant improvement were recorded in hydraulic conductivity, water stable aggregates and mean weight diameter. Soil pH, organic carbon and available phosphorus under different species did not reveal any significant changes, while significant reduction was observed in total nitrogen and potassium. Significant positive correlation was observed between WSA and iron content. Soil microbial population and enzyme activities were higher in control plot. Considering root distribution, biomass, soil hydraulic conductivity and water stable aggregates, B. bambos, B. vulgaris and D. hamiltonii are recommended for rehabilitation of degraded lands prone to soil erosion.

Rupture time of droplets impacted by a burst of picosecond laser pulses.

Liquid Sn droplets were irradiated with shaped bursts of picosecond laser pulses. The shapes of the deforming droplets following the impact of the recoil pressure induced by these bursts were imaged using a high-speed shadowgraph system. The rupture time t[over ̃]_{b} of the droplet expanding as a thin fluid film was measured for each case. A Rayleigh-Taylor instability analysis is done in order to determine the dependences governing t[over ̃]_{b}. The evidence supports the hypothesis that the initial perturbations of the developing Rayleigh-Taylor instabilities are on the order of the ablation depth and that there is a lower cutoff wavelength of these initial perturbations of ∼10µm.

A Lithium-Sulfur Battery using a 2D Current Collector Architecture with a Large-Sized Sulfur Host Operated under High Areal Loading and Low E/S Ratio.

While backless freestanding 3D electrode architectures for batteries with high loading sulfur have flourished in the recent years, the more traditional and industrially turnkey 2D architecture has not received the same amount of attention. This work reports a spray-dried sulfur composite with large intrinsic internal pores, ensuring adequate local electrolyte availability. This material offers good performance with a electrolyte content of 7 µL mg-1 at high areal loadings (5-8 mg cm-2 ), while also offering the first reported 2.8 µL mg-1 (8 mg cm-2 ) to enter into the second plateau of discharge and continue to operate for 20 cycles. Moreover, evidence is provided that the high-frequency semicircle (i.e., interfacial resistance) is mainly responsible for the often observed bypassing of the second plateau in lean electrolyte discharges.

Regression-based technique for improved optical rangefinding using tunable focus lenses.

In this paper, we present a novel method of target range estimation by tuning the spot size of a Gaussian beam at the plane of a reflective target. The beam spot size tuning is achieved through the use of a tunable focus lens (TFL). Using a carefully aligned sensor assembly, the diameter of the reflected beam is recorded at the plane of an imaging detector for different TFL focal length settings. This dataset is then used to estimate the distance of the target from the TFL. The proposed rangefinder is compact and requires minimal post-data-acquisition signal processing resulting in a fast response time compared to other spatial signal processing-based sensor designs. The estimation of target distance through a multiple data-point measurement dataset also ensures that the proposed method is robust to errors associated with obtaining range estimates from a single measurement data point. Experimental results demonstrate an excellent agreement with theory. With our proposed estimation method, we show a significant improvement in the measurement dynamic range of the sensor as well as its resolution compared to similar sensing schemes in prior art. We also experimentally demonstrate the possibility to extend the measurement dynamic range by incorporating a bias lens of a fixed focal length with the sensor module. The proposed sensor module is electronically controlled and consequently can be fully automated and compactly packaged with the use of commercially available miniature optical components.

Unraveling the Underlying Arrhythmia Mechanism in Persistent Atrial Fibrillation: Results From the STARLIGHT Study.

BACKGROUND: The mechanisms that initiate and sustain persistent atrial fibrillation are not well characterized. Ablation results remain significantly worse than in paroxysmal atrial fibrillation in which the mechanism is better understood and subsequent targeted therapy has been developed. The aim of this study was to characterize and quantify patterns of activation during atrial fibrillation using contact mapping. METHODS: Patients with persistent atrial fibrillation (n=14; mean age, 61±8 years; ejection fraction, 59±10%) underwent simultaneous biatrial contact mapping with 64 electrode catheters. The atrial electrograms were transformed into phase, and subsequent spatiotemporal mapping was performed to identify phase singularities (PSs). RESULTS: PSs were located in both atria, but we observed more PSs in the left atrium compared with the right atrium (779±302, 552±235; P=0.015). Although some PSs of duration sufficient to complete >1 rotation were detected, the maximum PS duration was only 1150 ms, and the vast majority (97%) of PSs persisted for too short a period to complete a full rotation. Although in selected patients there was evidence of PS local clustering, overall, PSs were distributed globally throughout both chambers with no clear anatomic predisposition. In a subset of patients (n=7), analysis was repeated using an alternative established atrial PS mapping technique, which confirmed our initial findings. CONCLUSIONS: No sustained rotors or localized drivers were detected, and instead, the mechanism of arrhythmia maintenance was consistent with the multiple wavelet hypothesis, with passive activation of short-lived rotational activity. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov. Unique identifier: NCT01765075.

Development, Preclinical Validation, and Clinical Translation of a Cardiac Magnetic Resonance - Electrophysiology System With Active Catheter Tracking for Ablation of Cardiac Arrhythmia.

OBJECTIVES: This study sought to develop an actively tracked cardiac magnetic resonance-guided electrophysiology (CMR-EP) system and perform first-in-human clinical ablation procedures. BACKGROUND: CMR-EP offers high-resolution anatomy, arrhythmia substrate, and ablation lesion visualization in the absence of ionizing radiation. Implementation of active tracking, where catheter position is continuously transmitted in a manner analogous to electroanatomic mapping (EAM), is crucial for CMR-EP to take the step from theoretical technology to practical clinical tool. METHODS: The setup integrated a clinical 1.5-T scanner, an EP recording and ablation system, and a real-time image guidance platform with components undergoing ex vivo validation. The full system was assessed using a preclinical study (5 pigs), including mapping and ablation with histological validation. For the clinical study, 10 human subjects with typical atrial flutter (age 62 ± 15 years) underwent MR-guided cavotricuspid isthmus (CTI) ablation. RESULTS: The components of the CMR-EP system were safe (magnetically induced torque, radiofrequency heating) and effective in the CMR environment (location precision). Targeted radiofrequency ablation was performed in all animals and 9 (90%) humans. Seven patients had CTI ablation completed using CMR guidance alone; 2 patients required completion under fluoroscopy, with 2 late flutter recurrences. Acute and chronic CMR imaging demonstrated efficacious lesion formation, verified with histology in animals. Anatomic shape of the CTI was an independent predictor of procedural success. CONCLUSIONS: CMR-EP using active catheter tracking is safe and feasible. The CMR-EP setup provides an effective workflow and has the potential to change the way in which ablation procedures may be performed.