Publications
112 results found
Kyriacou A, Hayat S, Qureshi N, et al., 2015, Dissociated pulmonary vein potentials: expression of the cardiac autonomic nervous system following pulmonary vein isolation?, HeartRhythm case reports, Vol: 1, Pages: 401-405, ISSN: 2214-0271
In the electrically nonisolated pulmonary veins, the cardiacautonomic system has been shown to play an important rolein initiating pulmonary vein (PV) ectopy and triggering atrialfibrillation (AF).1–3 However, the effects of the cardiacautonomic system on the isolated PV are not currentlyknown. We present the observations from a case whereopportunistic stimulation of the autonomic system wasperformed in the presence of dissociated pulmonary veinpotentials (PVPd).
Gill D, Jabbour R, Qureshi N, et al., 2015, Cerebellar Hemorrhage Presenting with Ventricular Tachycardia, JOURNAL OF STROKE & CEREBROVASCULAR DISEASES, Vol: 24, Pages: E311-E313, ISSN: 1052-3057
Sohaib SMA, Wright I, Lim E, et al., 2015, Atrioventricular Optimized Direct His Bundle Pacing Improves Acute Hemodynamic Function in Patients With Heart Failure and PR Interval Prolongation Without Left Bundle Branch Block, JACC: Clinical electrophysiology, Vol: 1, Pages: 582-591, ISSN: 2405-5018
ObjectivesThe purpose of this study was to investigate whether heart failure patients with narrow QRS duration (or right bundle branch block) but with long PR interval gain acute hemodynamic benefit from atrioventricular (AV) optimization. We tested this with biventricular pacing and (to deliver pure AV shortening) direct His bundle pacing.BackgroundBenefits of pacing for heart failure have previously been indicated by acute hemodynamic studies and verified in outcome studies. A new target for pacing in heart failure may be PR interval prolongation, which is associated with 58% higher mortality regardless of QRS duration.MethodsWe enrolled 16 consecutive patients with systolic heart failure, PR interval prolongation (mean, 254 ± 62 ms) and narrow QRS duration (n = 13; mean QRS duration: 119 ± 17 ms) or right bundle branch block (n = 3; mean, QRS duration: 156 ± 18 ms). We successfully delivered temporary direct His bundle pacing in 14 patients and temporary biventricular pacing in 14 participants. We performed AV optimization using invasive systolic blood pressure obtaining parabolic responses (mean R2: 0.90 for His, and 0.85 for biventricular pacing).ResultsThe mean increment in systolic BP compared with intrinsic ventricular conduction was 4.1 mm Hg (95% confidence interval [CI]: +1.9 to +6.2 mm Hg for His and 4.3 mm Hg [95% CI: +2.0 to +6.5 mm Hg] for biventricular pacing. QRS duration lengthened with biventricular pacing (change = +22 ms [95% CI: +18 to +25 ms]) but not with His pacing (change = +0.5 ms [95% CI: −2.6 to +3.6 ms).ConclusionsAV-optimized pacing improves acute hemodynamic function in patients with heart failure and long PR interval without left bundle branch block. That it can be achieved by single-site His pacing shows that its mechanism is AV shortening. The improvement is ∼60% of the effect size previously reported for biventricular pacing in left bundle branch block. Randomized, blinded trials are warranted to tes
Tzortzis KN, Roney CH, Qureshi NA, et al., 2015, Influence of left atrial geometry on rotor core trajectories in a model of atrial fibrillation, Computing in Cardiology, Publisher: IEEE, Pages: 481-484, ISSN: 2325-8861
Left atrial anatomy and myocardial architecture areknown to influence rotor initiation and maintenance.However, identifying their relative contribution clinicallyis challenging. The present study aims to investigate insilico the effect of left atrial geometry in isolation onrotor generation and evolution through thespatiotemporal tracking of phase singularities. Aftermeandering for a short period of time, rotors areattracted to specific areas of the chamber where there ishigh curvature, primarily near the base of the left atrialappendage and the junctions of the pulmonary veins. Thissuggests that the left atrial anatomy could play a key rolein the perpetuation of fibrillatory activity.
Ali RL, Cantwell CD, Qureshi NA, et al., 2015, Automated fiducial point selection for reducing registration error in the co-localisation of left atrium electroanatomic and imaging data., 2015 37th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), Publisher: IEEE, Pages: 1989-1992, ISSN: 1557-170X
Registration of electroanatomic surfaces and segmented images for the co-localisation of structural and functional data typically requires the manual selection of fiducial points, which are used to initialise automated surface registration. The identification of equivalent points on geometric features by the human eye is heavily subjective, and error in their selection may lead to distortion of the transformed surface and subsequently limit the accuracy of data co-localisation. We propose that the manual trimming of the pulmonary veins through the region of greatest geometrical curvature, coupled with an automated angle-based fiducial-point selection algorithm, significantly reduces target registration error compared with direct manual selection of fiducial points.
Luther V, Qureshi N, Kanagaratnam P, et al., 2015, Automated Activation and Pace-Mapping to Guide Ablation Within the Outflow Tract, Journal of Cardiovascular Electrophysiology, Vol: 27, Pages: 127-128, ISSN: 1540-8167
Koa-Wing M, Nakagawa H, Luther V, et al., 2015, A diagnostic algorithm to optimize data collection and interpretation of Ripple Maps in atrial tachycardias, International Journal of Cardiology, Vol: 199, Pages: 391-400, ISSN: 1874-1754
BackgroundRipple Mapping (RM) is designed to overcome the limitations of existing isochronal 3D mapping systems by representing the intracardiac electrogram as a dynamic bar on a surface bipolar voltage map that changes in height according to the electrogram voltage–time relationship, relative to a fiduciary point.ObjectiveWe tested the hypothesis that standard approaches to atrial tachycardia CARTO™ activation maps were inadequate for RM creation and interpretation. From the results, we aimed to develop an algorithm to optimize RMs for future prospective testing on a clinical RM platform.MethodsCARTO-XP™ activation maps from atrial tachycardia ablations were reviewed by two blinded assessors on an off-line RM workstation. Ripple Maps were graded according to a diagnostic confidence scale (Grade I — high confidence with clear pattern of activation through to Grade IV — non-diagnostic). The RM-based diagnoses were corroborated against the clinical diagnoses.Results43 RMs from 14 patients were classified as Grade I (5 [11.5%]); Grade II (17 [39.5%]); Grade III (9 [21%]) and Grade IV (12 [28%]). Causes of low gradings/errors included the following: insufficient chamber point density; window-of-interest < 100% of cycle length (CL); < 95% tachycardia CL mapped; variability of CL and/or unstable fiducial reference marker; and suboptimal bar height and scar settings.ConclusionsA data collection and map interpretation algorithm has been developed to optimize Ripple Maps in atrial tachycardias. This algorithm requires prospective testing on a real-time clinical platform.
Hocini M, Shah AJ, Neumann T, et al., 2015, Focal Arrhythmia Ablation Determined by High-Resolution Noninvasive Maps: Multicenter Feasibility Study, JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Vol: 26, Pages: 754-760, ISSN: 1045-3873
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- Citations: 16
Leong KMW, Ng FS, Roney C, et al., 2015, DYNAMIC CHARACTERISATION OF THE ELECTROPHYSIOLOGICAL SUBSTRATE IN BRUGADA SYNDROME DURING PHYSIOLOGICAL AUTONOMIC STIMULATION, British-Cardiac-Society (BCS) Annual Conference on Hearts and Genes, Publisher: BMJ PUBLISHING GROUP, Pages: A36-A37, ISSN: 1355-6037
Lim PB, Kanagaratnam P, 2015, The left atrial neural network: more complicated than we thought?, FUTURE CARDIOLOGY, Vol: 11, Pages: 251-254, ISSN: 1479-6678
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- Citations: 1
Luther V, Jamil-Copley S, Koa-Wing M, et al., 2015, Non-randomised comparison of acute and long-term outcomes of robotic versus manual ventricular tachycardia ablation in a single centre ischemic cohort., Journal of Interventional Cardiac Electrophysiology, Vol: 43, Pages: 175-185, ISSN: 1572-8595
INTRODUCTION: Robotically guided radiofrequency (RF) ablation offers greater catheter stability that may improve lesion depth. We performed a non-randomised comparison of patients undergoing ventricular tachycardia (VT) ablation either manually or robotically using the Hansen Sensei system for recurrent implantable defibrillator (ICD) therapy. METHODS: Patients with infarct-related scar underwent VT ablation using the Hansen system to assess feasibility compared with patients undergoing manual VT ablation during a similar time period. Power delivery during robotic ablation was restricted to 30 W at 60 s. VT inducibility was checked at the end of the procedure. Pre-ablation ICD therapy burdens over 6 months were compared with post-ablation therapy averaged to a 6-month period. RESULTS: Twelve consecutive patients who underwent robotic VT ablation were compared to 12 consecutive patients undergoing a manual ablation. Patient demographics and comorbidities were similar in the two groups. A higher proportion of robotic cases were urgent (9/12 (75 %)) vs. manual (4/12 (33 %)) (p = 0.1). Post-ablation VT stimulation did not induce clinical VT in 11/12 (92 %) in each group. There were no peri-procedural complications related to ablation delivery. Patients were followed up for approximately 2 years. Averaged over 6 months, robotic ICD therapy burdens fell from 32 (5-400) events to 2.5 (0-11) (p = 0.015). Therapy burden fell from 14 (10-25) to 1 (0-5) (p = 0.023) in the manual group. There was no difference in long-term outcome (p = 0.60) and mortality (4/12 (33 %), p = 1.0). CONCLUSION: Robotically guided VT ablation is both feasible and safe when compared to manual ablation with good acute and long-term outcomes.
Leong KMW, Lim PB, Kanagaratnam P, 2015, Comparative analysis of diagnostic 12-lead electrocardiography and 3-dimensional noninvasive mapping., Card Electrophysiol Clin, Vol: 7, Pages: 71-78
The clinical utility of noninvasive electrocardiographic imaging has been demonstrated in a variety of conditions. It has recently been shown to have superior predictive accuracy and higher clinical value than validated 12-lead electrogram algorithms in the localization of arrhythmias arising from the ventricular outflow tract, and displays similar potential in other conditions.
Finegold J, Bordachar P, Kyriacou A, et al., 2015, Atrioventricular delay optimization of cardiac resynchronisation therapy: Comparison of non-invasive blood pressure with invasive haemodynamic measures, INTERNATIONAL JOURNAL OF CARDIOLOGY, Vol: 180, Pages: 221-222, ISSN: 0167-5273
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- Citations: 7
Roney CH, Tzortzis KN, Cantwell CD, et al., 2015, A Technique for Visualising Three-Dimensional Left Atrial Cardiac Activation Data in Two Dimensions with Minimal Distance Distortion, 37th Annual International Conference of the IEEE-Engineering-in-Medicine-and-Biology-Society (EMBC), Publisher: IEEE, Pages: 7296-7299, ISSN: 1557-170X
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- Citations: 6
Koa-Wing M, Jamil-Copley S, Ariff B, et al., 2014, Haemorrhagic cerebral air embolism from an atrio-oesophageal fistula following atrial fibrillation ablation., Perfusion, Vol: 30, Pages: 484-486, ISSN: 0935-0020
We report the case of a man found unconscious three weeks following atrial fibrillation (AF) ablation. Cranial and thoracic imaging demonstrated multiple areas of pneumo-embolic infarction secondary to an atrio-oesophageal fistula (AEF). AEF is a recognised, but rare, complication of AF ablation.(1-8) Early recognition is critical as the mortality is 100% without surgical intervention. We consider the postulated mechanisms of AEF formation, the spectrum of clinical presentation, investigations and treatment.
Luther V, Jamil-Copley S, Shun-Shin M, et al., 2014, 24Acute and long-term outcomes for patients undergoing radiofrequency catheter ablation of scar-related ventricular tachycardia by robotic catheter navigation., Europace, Vol: 16 Suppl 3
Robotically-guided ablation offers theoretical advantages with greater catheter stability that can improve lesion depth. We performed a non-randomised comparison of patients undergoing ventricular tachycardia (VT) ablation either manually or using the Hansen robotic system.
Jamil-Copley SJ, Linton NL, Koa-Wing MK, et al., 2014, 3Development of a novel mapping system to visualise activation in ventricular scar., Europace, Vol: 16 Suppl 3
Ventricular scar is characterised by fractionated electrograms (egm) and not well displayed by current 3D mapping systems. We hypothesised that displaying intracardiac egms on 3D geometry as dynamic bars changing height according to the voltage-time relationship relative to a fiduciary egm, would enable visualisation slow conduction channels (SCC) in the infarct scar.
Sau A, Qureshi N, Bai W, et al., 2014, Late-gadolinium enhanced cardiac MRI defined scar is predominantly located on the left atrial septum and posterior wall in patients with persistent atrial fibrillation, Annual Meeting of the European-Society-of-Cardiology (ESC), Publisher: OXFORD UNIV PRESS, Pages: 799-799, ISSN: 0195-668X
Sau A, Mereu R, Taraborrelli P, et al., 2014, A long-term follow-up of patients with prolonged asystole > 15secs on head-up tilt testing, Annual Meeting of the European-Society-of-Cardiology (ESC), Publisher: OXFORD UNIV PRESS, Pages: 1066-1066, ISSN: 0195-668X
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- Citations: 1
Sau A, Qureshi N, Roney C, et al., 2014, The influence of late-gadolinium enhanced cardiac MRI defined scar on left atrial electrophysiological properties in patients with persistent atrial fibrillation, Annual Meeting of the European-Society-of-Cardiology (ESC), Publisher: OXFORD UNIV PRESS, Pages: 780-780, ISSN: 0195-668X
Mereu R, Sau A, Lim PB, 2014, Diagnostic algorithm for syncope, AUTONOMIC NEUROSCIENCE-BASIC & CLINICAL, Vol: 184, Pages: 10-16, ISSN: 1566-0702
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- Citations: 5
Roney CH, Cantwell C, Qureshi NA, et al., 2014, An Automated Algorithm for Determining Conduction Velocity, Wavefront Direction and Focal Source Location using a Multipolar Catheter, IEEE Engineering in Medicine and Biology Conference
Determining locations of focal arrhythmia sources and quantifying myocardial conduction velocity (CV) are two major challenges in clinical catheter ablation cases. CV, wavefront direction and focal source location can be estimated from multipolar catheter data, but currently available methods are time-consuming, limited to specific electrode configurations, and can be inaccurate. We developed automated algorithms to rapidly identify CV from multipolar catheter data with any arrangement of electrodes, whilst providing estimates of wavefront direction and focal source position, which can guide the catheter towards a focal arrhythmic source. We validated our methods using simulations on realistic human left atrial geometry. We subsequently applied them to clinically-acquired intracardiac electrogram data, where CV and wavefront direction were accurately determined in all cases, whilst focal source locations were correctly identified in 2/3 cases. Our novel automated algorithms can potentially be used to guide ablation of focal arrhythmias in real-time in cardiac catheter laboratories.
Cantwell C, Roney CH, Ali RL, et al., 2014, A Software Platform for the Comparative Analysis of Electroanatomic and Imaging Data including Conduction Velocity Mapping, IEEE Engineering in Medicine and Biology Conference
Electroanatomic mapping systems collect increasingly large quantities of spatially-distributed electrical data which may be potentially further scrutinized post-operatively to expose mechanistic properties which sustain and perpetuate atrial fibrillation. We describe a modular software platform, developed to post-process and rapidly analyse data exported from electroanatomic mapping systems using a range of existing and novel algorithms. Imaging data highlighting regions of scar can also be overlaid for comparison. In particular, we describe the conduction velocity mapping algorithm used to highlight wavefront behaviour. Conduction velocity was found to be particularly sensitive to the spatial distribution of the triangulation points and corresponding activation times. A set of geometric conditions were devised for selecting suitable triangulations of the electrogram set for generating CV maps.
Finegold J, Bordachar P, Kyriacou A, et al., 2014, CORRELATION AND REPRODUCIBILITY OF INVASIVE AND NON-INVASIVE HAEMODYNAMIC PARAMETERS FOR IDENTIFYING OPTIMAL AV DELAY IN CARDIAC RESYNCHRONISATION THERAPY, HEART, Vol: 100, Pages: A22-A23, ISSN: 1355-6037
Sohaib SMA, Jones S, Kyriacou A, et al., 2014, EVIDENCE THAT HAEMODYNAMIC RESPONSE TO VV DELAY OPTIMISATION OF CRT DEVICES MAY BE SIMPLY A FUNCTION OF THE METHOD OF PROGRAMMING AV DELAY, HEART, Vol: 100, Pages: A21-A22, ISSN: 1355-6037
Amon P, Irvine R, Taraborrelli P, et al., 2014, Dysautonomia and Foregut Dysmotility in the Joint Hypermobility Syndrome, 55th Annual Meeting of the Society-for-Surgery-of-the-Alimentary-Tract (SSAT) / Digestive Disease Week (DDW), Publisher: W B SAUNDERS CO-ELSEVIER INC, Pages: S896-S897, ISSN: 0016-5085
Jamil-Copley S, Bokan R, Kojodjojo P, et al., 2014, Noninvasive electrocardiographic mapping to guide ablation of outflow tract ventricular arrhythmias, HEART RHYTHM, Vol: 11, Pages: 587-594, ISSN: 1547-5271
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- Citations: 60
Kyriacou A, Pabari PA, Mayet J, et al., 2014, Cardiac resynchronization therapy and AV optimization increase myocardial oxygen consumption, but increase cardiac function more than proportionally, INTERNATIONAL JOURNAL OF CARDIOLOGY, Vol: 171, Pages: 144-152, ISSN: 0167-5273
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- Citations: 12
Sutton R, Salukhe TV, Franzen-Mcmanus A-C, et al., 2014, Ivabradine in treatment of sinus tachycardia mediated vasovagal syncope, EUROPACE, Vol: 16, Pages: 284-288, ISSN: 1099-5129
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- Citations: 23
Ali RL, Cantwell CD, Roney CH, et al., 2014, A novel method for quantifying localised correlation of late-gadolinium intensity with conduction velocity, Computing in Cardiology (CinC) 2014, Pages: 193-196
Patient-specific computer models of the human atria have the potential to aid clinical intervention in the treatment of cardiac arrhythmias. However, quantifying and integrating the heterogeneous qualities of the myocardium through imaging is particularly challenging due to the unknown relationship between voxel intensity and tissue conductivities. We establish a method to determine the relationship between local conduction velocity and scar density, extracted through the analysis of late-gadolinium enhanced magnetic resonance imaging data.
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