A new mechanism for void-cascade interaction from nondestructive depth-resolved atomic-scale measurements of ion irradiation-induced defects in Fe

The nondestructive investigation of single vacancies and vacancy clusters in ion-irradiated samples requires a depth-resolved probe with atomic sensitivity to defects. The recent development of short-pulsed positron beams provides such a probe. Here, we combine depth-resolved Doppler broadening and positron annihilation lifetime spectroscopies to identify vacancy clusters in ion-irradiated Fe and measure their density as a function of depth. Despite large concentrations of dislocations and voids in the pristine samples, positron annihilation measurements uncovered the structure of vacancy clusters and the change in their size and density with irradiation dose. When combined with transmission electron microscopy measurements, the study demonstrates an association between the increase in the density of small vacancy clusters with irradiation and a remarkable reduction in the size of large voids. This, previously unknown, mechanism for the interaction of cascade damage with voids in ion-irradiated materials is a consequence of the high porosity of the initial microstructure.

P1000Aetiology and efficacy of atrial fibrillation ablation in young adults

Introduction

Little is known regarding the aetiology or outcome of atrial fibrillation (AF) occurring in young adults. This retrospective analysis was performed to explore the demographics and efficacy of AF ablation in this population.

Methods

Patients were included who had undergone ≥1 AF ablation under the age of 40 between 2006-2018. Recurrence was defined as return of either documented AF or previous symptoms for >30s following a 3-month blanking period. Initial exploratory co-variates were included in a univariate analysis and those terms with P-value of <0.1 were then used to generate a Cox proportional-hazards multivariate model.

Results

124 patients (33.6 ± 4.7 yrs, 77% men), initially presenting with paroxysmal AF (pAF; n = 97) or persistent AF (n = 27), underwent 175 AF ablation procedures. 22.6% (n = 28) also had atrial flutter. Time from symptom onset to first ablation was 50.7 ± 46.2 months. Relevant cardiovascular-related demographics were analysed: hypertension in 8.9% (n = 11); diabetes in 1.6% (n = 2); positive family history of AF in 12.9% (n = 16); and family history of sudden cardiac death in 2.4% (n = 3). Mean CHA2DS2-VASc score was 0.35. Of those patients with documented echocardiogram imaging (n = 91), 26.4% (n = 24) had LA dilatation and 6.6% (n = 6) had LV dysfunction. Patients with LA dilatation underwent more ablations (2.3 ± 0.3) compared to controls (1.5 ± 0.1; p < 0.001).

Ablation strategy was pulmonary vein isolation (PVI) only in 67.2% (n = 119), with additional ablation in the remaining: roof line in 18.9% (n = 33); cavotricuspid isthmus line in 13.1% (n = 23); mitral isthmus line in 2.3% (n = 4); superior vena cava isolation in 2.3% (n = 4); complex fractionated atrial electrograms in 14.9% (n = 26). Mean procedure time was 155 ± 41 min, mean ablation time was 1657 ± 991 s and mean fluoroscopy time was 32.6 ± 23.4 min. General anaesthesia was used in 43.4% (n = 76). Complications included femoral haematoma (n = 2), tamponade (n = 1) and pulmonary vein stenosis (n = 2).

90 days of follow-up was available for 137 procedures performed for pAF (n = 105) and persistent AF (n = 32). For pAF, overall recurrence was 61.9% for first ablations and 62.9% overall. Recurrence was 56.3% for persistent AF.

Factors significantly associated with increased AF recurrence in univariate analysis were

male gender (hazard ratio (HR) 2.3, 95% confidence interval (CI): 1.2-4.4, p = 0.011), hypertension (HR 0.5, CI: 0.2-1.1, p = 0.067), family history of sudden cardiac death (HR 6.8, CI: 1.6-29.0 , p = 0.010) and enlarged LA size (HR 2.2, CI: 1.3-3.6, p = 0.003). In multivariate analysis, the only significant predictor of poor outcome was enlarged LA size (HR 2.0, 95% CI: 1.2-3.5, p = 0.011).

Conclusions

Young patients with AF may have structurally abnormal hearts, and therefore do not only present with lone AF. LA size may be used as a predictor for success. Surveillance imaging may be useful to detect future structural change, which will be the subject of future prospective studies.

Abstract Figure. AF ablation recurrence in young adults

P1381Improved outcome in ablation of ventricular tachycardia in patients with structural heart disease under general anaesthetic

Background

Catheter ablation is an important adjunct to device implantation for secondary prevention of ventricular tachycardia (VT). However, several factors may influence the success of ablations in terms of long-term freedom from VT recurrence. A thus far little examined factor is the use of general anaesthetic (GA) versus conscious sedation during the procedure, which has been shown to improve outcomes in persistent atrial fibrillation (AF) ablation.

Methods

Patients with structural heart disease VT undergoing ablations from January 2015 to March 2019 were retrospectively followed up at a single centre. End points were recurrent VT or device therapy (shock or anti-tachycardia pacing) at one year. Hazard ratios (HR) were generated using a multivariate Cox-regression proportional hazards model including variables of age at ablation, sex, amiodarone use at time of ablation, scar age, left ventricular ejection fraction, use of GA, and diagnosis of: diabetes mellitus (DM), hypertension (HTN), renal impairment or AF.

Results

79 patients (74 male, mean age 68.2+/- 10.3 years) were included. A substrate-based strategy of late potential ablation was employed. 69 had ischaemic and 10 had non-ischaemic cardiomyopathy. Mean scar age was 13.8 +/- 9.8 years; EF was 40-50% in 27 patients, 30-40% in 26 and < 30% in 26. 37 patients had implantable cardioverter defibrillators and 30 had cardiac resynchronisation therapy (CRT) defibrillator devices, 1 had a CRT- pacemaker device and 4 had dual chamber pacemakers. Comorbidities were: DM (16), HTN (31), renal impairment (13), AF (31). 62 patients (79.5%) were on amiodarone at the time of ablation. Mean procedure duration was 234.8 +/- 44.5 min and mean radiofrequency energy application time was 2247 +/- 862 s. 61 were first procedures and 18 were repeat procedures. One patient suffered a complication of groin haematoma. 62 patients (78.5%) underwent VT ablation under GA and 17 (21.5%) under sedation of midazolam and fentanyl. Patient characteristics did not differ between groups. Significant factors which increased freedom from VT recurrence or device therapy were HTN (88.9% vs 59.4%, HR 0.72, 95% confidence interval (CI): 0.007-0.75, p= 0.028), amiodarone treatment (50.0% vs 76.3%, HR 0.036, 95% CI: 0.003-0.404, p = 0.036) and ablation under GA rather than sedation (50.0% vs 75.0%, HR 0.055, 95% CI: 0.006-0.495, p = 0.01) (Fig 1).

Conclusions

In patients with structural heart disease undergoing VT ablation, outcomes are improved with the use of GA over conscious sedation.

Abstract Figure 1

P1419Persistent atrial fibrillation terminates during ablation more often using dispersion mapping than with fractionated electrogram mapping

Introduction

Persistent AF termination rates have increased since the advent of AF driver mapping, with a recent meta-analysis (Baykaner Circ AE 2018) of over 3200 patients showing improved 12 month freedom from AF/AT.  However,  recent randomised clinical trials have cast doubt on the efficacy of complex fractionated atrial electrograms (CFAE) based mapping strategies. We

set out to study a consecutive single centre series pre-and post- use of spatio-temporal dispersion (STD) to identify termination rates between the two approaches.

Methods

We recruited consecutive patients over 18 months at a single high volume tertiary centre undergoing first redo ablation for persistent AF. Patients were all

mapped using Pentarray to mark areas of substrate using the spatio-temporal dispersion (STD) method (Seitz JACC 2017).

Ablation was performed by a single operator using catheters to standardise equipment and workflow, to enable true

comparison of mapping and ablation results in a consecutive series.

Results

In total 38 patients were studied at redo ablation for persistent AF (age 69, 87% male, LA diameter 4.5cm). Termination of persistent

AF to SR (30%) or AT (70%) was obtained in 30/38 (79%) of the group with STD based substrate ablation vs. 1/38 (3%) in patients mapped

with CFAE targeting using identical equipment and operator (p < 0.001). Procedure time was no different between STD and CFAE based

approaches (263 vs. 248 mins, p = ns). Figure shows STD patterns (red arrows) on Pentarray in a 67 year old man anterior to left inferior

pulmonary vein (A), where ablation terminated AF to sinus rhythm. At 12 month follow up, 30/38 (79%) patients were in sinus rhythm with no AF detected on ECG or continuous monitoring.

Conclusions

In this single centre series of persistent AF ablations, the use of STD mapping increased rates of termination compared to a fractionation based mapping strategy alone, without increasing overall procedure time. Clinical outcome data suggest this translates into better 12 month clinical outcomes, and motivate prospective randomised trials to definitively study this technique.

Abstract Figure.

P1451Catheter ablation in adults with Wolff-Parkinson-White syndrome: a "real-life" experience

Introduction. Radiofrequency catheter ablation (RFA) is 1st line treatment in symptomatic adult patients with Wolff-Parkinson-White syndrome (WPW). Patients with WPW are often quoted a high success rate for RFA but does this reflect reality? There is a paucity of recent literature and ongoing service developments in the UK may have a negative impact on success by reducing individual operator experience of adult WPW cases (i.e. increasing numbers of cardiac electrophysiologists in each department, patients more likely to undergo RFA as children). In contrast, technological developments (e.g. 3D mapping, steerable sheaths) may have a positive impact on success of RFA in WPW.

Methods. We collected data on all patients with WPW scheduled for 1st time ablation between Jan 2006 and Dec 2018. All patients undergoing re-do RFA during this time were excluded. For comparison, we divided this timeframe into three periods: 2006-9, 2010-13 and 2014-18.

Results. The number of patients scheduled for RFA and the outcome is listed in the Table. The overall success rate was 86.5% and this figure remained constant throughout the 13 year time-frame. Significant complications occurred in 1.17% of cases. 19.9% of patients scheduled for an ablation had no ablation attempted for various reasons (‘safe’ pathway, proximity to AV node etc).

Conclusion. In our centre, the number of adult cases of WPW scheduled for RFA year-on-year remains constant. The complication rate is in line with published literature. The RFA success rate is lower than the published data. As expected, success rate of RFA for WPW varies according to accessory pathway location. 1 in 5 cases scheduled for ablation did not proceed to ablation. This highlights an area where more effective resource planning from the outset can be undertaken.

Table 2006-9 2010-13 2014-18 Patients scheduled for RFA, n 181 152 179 Patients who underwent RFA, n 162 121 127 Overall RFA success rate, % (n) 85.6 (160) 86.6 (119) 87.4 (127) Success rate by AP location, % (n) Free wall Left 91.5 (71) 91.8 (49) 95.3 (64) Right 76.9 (13) 77.8 (9) 60.0 (5) Septal Anterior 77.8 (9) 88.9 (9) 100.0 (4) Mid 75.0 (8) 90.0 (10) 66.7 (3) Posterior 86.0 (57) 82.9 (41) 79.6 (49) RFA success rate in patients with Wolff-Parkinson-White syndrome. AP = accessory pathway, RFA = radiofrequency catheter ablation

The incidence and effect of resternotomy following cardiac surgery on morbidity and mortality: a 1-year national audit on behalf of the Association of Cardiothoracic Anaesthesia and Critical Care

Over 30,000 adult cardiac operations are carried out in the UK annually. A small number of these patients need to return to theatre in the first few days after the initial surgery, but the exact proportion is unknown. The majority of these resternotomies are for bleeding or cardiac tamponade. The Association of Cardiothoracic Anaesthesia and Critical Care carried out a 1-year national audit of resternotomy in 2018. Twenty-three of the 35 centres that were eligible participated. The overall resternotomy rate (95%CI) within the period of admission for the initial operation in these centres was 3.6% (3.37-3.85). The rate varied between centres from 0.69% to 7.6%. Of the 849 patients who required resternotomy, 127 subsequently died, giving a mortality rate (95%CI) of 15.0% (12.7-17.5). In patients who underwent resternotomy, the median (IQR [range]) length of stay on ICU was 5 (2-10 [0-335]) days, and time to tracheal extubation was 20 (12-48 [0-2880]) hours. A total of 89.3% of patients who underwent resternotomy were transfused red cells, with a median (IQR [range]) of 4 (2-7 [1-1144]) units of red blood cells. The rate (95%CI) of needing renal replacement therapy was 23.4% (20.6-26.5). This UK-wide audit has demonstrated that resternotomy after cardiac surgery is associated with prolonged intensive care stay, high rates of blood transfusion, renal replacement therapy and very high mortality. Further research into this area is required to try to improve patient care and outcomes in patients who require resternotomy in the first 24 h after cardiac surgery.

Advanced-PRF: Clinical evaluation in impacted mandibular third molar sockets

OBJECTIVE

This prospective study evaluated the efficacy and healing potential of modified formulation of PRF, commonly known as Advanced PRF (A-PRF) in impacted mandibular third molar extraction sockets.

MATERIALS AND METHODS

20 patients with bilateral impacted mandibular third molars were included in this study. Surgical disimpactions were done at 3-4 weeks interval in opposing quadrants of patient. One quadrant received A-PRF while the opposing quadrant in same patient was taken as control. Comparative evaluation was done in terms of pain assessment, analgesics required, swelling, soft tissue healing and trismus on 1st, 3 and 7day follow-up. Comparative assessment of bone healing was also done on 1st, 3and 6month follow-up.

RESULTS

This study involved 12 female and 8 male patients with in age range of 18-35 years. The evaluation of pain, swelling, trismus and soft tissue healing on 3rd postoperative day revealed considerable improvement on A-PRF sites as compared to control sites. The outcomes were found to be statistically significant with p values 0.008, 0.031, 0.0001, 0.05 respectively. Even the analgesic consumption was remarkably less when A-PRF was used (P=0.004). Bone healing evaluation in A-PRF sites on 1st, 3and 6month has shown significantly improved results with P<0.05.

CONCLUSION

Our study infers that A-PRF has enhanced the healing potential of soft tissue as well as bone in extraction socket. Apart from that it has also shown promising results in relief of immediate postoperative symptoms like pain, swelling and trismus which improves the comfort and acceptability of surgical procedures by patients. Enhanced healing and patient comfort in cost effective manner are the highlighting features of A-PRF.

Impact of comorbidities on perioperative outcomes for carcinoma of oral cavity

INTRODUCTION

Surgical management of oral cavity carcinoma involves composite resection with reconstruction. Comorbidities increase the risk of perioperative complications. Objective stratification is important for uneventful recovery. The Charlson Comorbidity Index and the Washington University Head and Neck Comorbidity Index were used to assess perioperative morbidity and mortality.

MATERIALS AND METHODS

This was a prospective study of 531 patients with head and neck squamous cell carcinoma who were treated between January 2014 and December 2017. Patients' comorbidity scores on the Charlson Comorbidity Index and Washington University Head and Neck Comorbidity Index were recorded.

RESULTS

The median age of the cohort was 49 years. Median Charlson Comorbidity Index score was 3 and Washington University Head and Neck Comorbidity Index was 0. There were five mortalities with a Charlson Comorbidity Index score of 4 or more. Fifteen patients had either infection, leak or postoperative bleeding. A Charlson Comorbidity Index of 4 or more was associated with higher event rate and poor overall survival (p=0.001).

CONCLUSION

Higher Charlson Comorbidity Index score is associated with increased incidence of peri-operative morbidity and mortality, while the Washington University Head and Neck Comorbidity Index is a poor predictor of the same.

Venetoclax, bendamustine, and rituximab in patients with relapsed or refractory NHL: a phase Ib dose-finding study

Background

Venetoclax is a selective, potent inhibitor of the anti-apoptotic B-cell leukemia/lymphoma-2 protein approved for treatment of chronic lymphocytic leukemia. We conducted a dose-finding study of venetoclax in combination with bendamustine-rituximab (BR) in patients with relapsed/refractory non-Hodgkin's lymphoma (NHL).

Patients and methods

BR was given for six cycles at standard doses. Intermittent and continuous oral venetoclax administration was explored at 50-1200 mg daily doses. Co-primary objectives included safety, pharmacokinetics (PKs), maximum-tolerated dose (MTD), and recommended phase II dose (RP2D); secondary objective was preliminary efficacy.

Results

Sixty patients were enrolled: 32 with follicular lymphoma, 22 with diffuse large B-cell lymphoma, and 6 with marginal zone lymphoma. Nausea (70%), neutropenia (68%), diarrhea (55%), and thrombocytopenia (52%) were the most frequent adverse events (AEs). Most common grade 3/4 AEs were neutropenia (60%) and lymphopenia (38%). Serious AEs were reported in 24 patients; the most frequent were febrile neutropenia and disease progression (8% each). Five patients died from either disease progression (n = 4) or respiratory failure (n = 1). MTD was not reached; RP2D for venetoclax-BR combination was established as 800 mg daily continuously. Venetoclax PK exposure with and without BR was comparable. For all patients, overall response rate was 65%. Median duration of overall response, overall survival, and progression-free survival was 38.3 months [95% confidence interval (CI) 10.4-NR], not yet reached, and 10.7 months (95% CI 4.3-21.0), respectively.

Conclusions

This study established the safety profile of venetoclax in combination with BR, and results demonstrated tolerability and preliminary efficacy of the combination. Additional follow-up is needed to better determine the future role of BR plus venetoclax in the treatment of relapsed/refractory B-cell NHL.

Trial registered

Clinicaltrials.gov, NCT01594229.

Harmonically Confined Particles with Long-Range Repulsive Interactions

We study an interacting system of N classical particles on a line at thermal equilibrium. The particles are confined by a harmonic trap and repel each other via pairwise interaction potential that behaves as a power law ∝∑[under i≠j][over N]|x_{i}-x_{j}|^{-k} (with k>-2) of their mutual distance. This is a generalization of the well-known cases of the one-component plasma (k=-1), Dyson's log gas (k→0^{+}), and the Calogero-Moser model (k=2). Because of the competition between harmonic confinement and pairwise repulsion, the particles spread over a finite region of space for all k>-2. We compute exactly the average density profile for large N for all k>-2 and show that while it is independent of temperature for sufficiently low temperature, it has a rich and nontrivial dependence on k with distinct behavior for -2<k<1, k>1 and k=1.

Exploring organizational support for the provision of structured self-management education for people with Type 2 diabetes: findings from a qualitative study

AIM

To explore the organizational context in which Type 2 diabetes structured group education is provided.

METHODS

Four Clinical Commissioning Groups in England providing Type 2 diabetes structured self-management education participated in a qualitative study exploring the context for provision of that education. Using UK National Diabetes Audit returns, two Clinical Commissioning Groups were selected that had non-attendance rates of ≤25%, and two that had non-attendance rates of ≥50%. Between May 2016 and August 2017, 20 interviews were conducted with Clinical Commissioning Group staff including: commissioners, healthcare professionals, managers, general practitioners and diabetes educators. Data gathering was prolonged as it proved challenging to engage with healthcare staff as a result of frequent local restructuring and service disruption.

RESULTS

Local audits revealed discrepancies in basic data such as referral and attendance numbers compared with national audit data. There was a commonality in the themes identified from interviews: diabetes education was rarely embedded in service structure; where education uptake was poor, a lack of central support to delivery teams was noticeable; and where education uptake was positive, delivery teams were actively engaged, sometimes relying on enthusiastic individuals. Both situations put the local sustainability of diabetes education at risk.

CONCLUSIONS

There appears to be a link between attendance rates and organizational issues, therefore, when considering how to increase attendance rates, the state of the diabetes education infrastructure should be reviewed. Good uptake of diabetes education can be too reliant on the enthusiastic commitment of small teams or individuals delivering the education.