Imperial College London

DrZacharyWhinnett

Faculty of MedicineNational Heart & Lung Institute

Reader in Cardiac Electrophysiology
 
 
 
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z.whinnett

 
 
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South- NHLI Cardiovascular ScienceBlock B Hammersmith HospitalHammersmith Campus

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Publications

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212 results found

Su J, Manisty C, Parker KH, Simonsen U, Nielsen-Kudsk JE, Mellemkjaer S, Connolly S, Lim PB, Whinnett ZI, Malik IS, Watson G, Davies JE, Gibbs S, Hughes AD, Howard Let al., 2017, Wave Intensity Analysis Provides Novel Insights Into Pulmonary Arterial Hypertension and Chronic Thromboembolic Pulmonary Hypertension., Journal of the American Heart Association, Vol: 6, ISSN: 2047-9980

BACKGROUND: In contrast to systemic hypertension, the significance of arterial waves in pulmonary hypertension (PH) is not well understood. We hypothesized that arterial wave energy and wave reflection are augmented in PH and that wave behavior differs between patients with pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH). METHODS AND RESULTS: Right heart catheterization was performed using a pressure and Doppler flow sensor-tipped catheter to obtain simultaneous pressure and flow velocity measurements in the pulmonary artery. Wave intensity analysis was subsequently applied to the acquired data. Ten control participants, 11 patients with PAH, and 10 patients with CTEPH were studied. Wave speed and wave power were significantly greater in PH patients compared with controls, indicating increased arterial stiffness and right ventricular work, respectively. The ratio of wave power to mean right ventricular power was lower in PAH patients than CTEPH patients and controls. Wave reflection index in PH patients (PAH: ≈25%; CTEPH: ≈30%) was significantly greater compared with controls (≈4%), indicating downstream vascular impedance mismatch. Although wave speed was significantly correlated to disease severity, wave reflection indexes of patients with mildly and severely elevated pulmonary pressures were similar. CONCLUSIONS: Wave reflection in the pulmonary artery increased in PH and was unrelated to severity, suggesting that vascular impedance mismatch occurs early in the development of pulmonary vascular disease. The lower wave power fraction in PAH compared with CTEPH indicates differences in the intrinsic and/or extrinsic ventricular load between the 2 diseases.

Journal article

Leong KMW, Ng FS, yao C, Roney C, Linton N, Whinnett Z, lefroy D, Davies DW, Lim PB, Harding S, Peters N, Kanagaratnam P, Varnava Aet al., 2017, ST-Elevation Magnitude Correlates With Right Ventricular Outflow Tract Conduction Delay in Type I Brugada ECG, Circulation: Arrhythmia and Electrophysiology, Vol: 10, ISSN: 1941-3084

Background: The substrate location and underlying electrophysiological mechanisms that contribute to the characteristic ECG pattern of Brugada syndrome (BrS) are still debated. Using noninvasive electrocardiographical imaging, we studied whole heart conduction and repolarization patterns during ajmaline challenge in BrS individuals.Methods and Results: A total of 13 participants (mean age, 44±12 years; 8 men), 11 concealed patients with type I BrS and 2 healthy controls, underwent an ajmaline infusion with electrocardiographical imaging and ECG recordings. Electrocardiographical imaging activation recovery intervals and activation timings across the right ventricle (RV) body, outflow tract (RVOT), and left ventricle were calculated and analyzed at baseline and when type I BrS pattern manifested after ajmaline infusion. Peak J-ST point elevation was calculated from the surface ECG and compared with the electrocardiographical imaging–derived parameters at the same time point. After ajmaline infusion, the RVOT had the greatest increase in conduction delay (5.4±2.8 versus 2.0±2.8 versus 1.1±1.6 ms; P=0.007) and activation recovery intervals prolongation (69±32 versus 39±29 versus 21±12 ms; P=0.0005) compared with RV or left ventricle. In controls, there was minimal change in J-ST point elevation, conduction delay, or activation recovery intervals at all sites with ajmaline. In patients with BrS, conduction delay in RVOT, but not RV or left ventricle, correlated to the degree of J-ST point elevation (Pearson R, 0.81; P<0.001). No correlation was found between J-ST point elevation and activation recovery intervals prolongation in the RVOT, RV, or left ventricle.Conclusions: Magnitude of ST (J point) elevation in the type I BrS pattern is attributed to degree of conduction delay in the RVOT and not prolongation in repolarization time.

Journal article

Sau A, Sikkel MB, Luther V, Wright I, Guerrero F, Koa-Wing M, Lefroy D, Linton N, Qureshi N, Whinnett Z, Lim PB, Kanagaratnam P, Peters NS, Davies DWet al., 2017, The sawtooth EKG pattern of typical atrial flutter is not related to slow conduction velocity at the cavotricuspid isthmus., Journal of Cardiovascular Electrophysiology, Vol: 28, Pages: 1445-1453, ISSN: 1045-3873

INTRODUCTION: We hypothesized that very high density mapping of typical atrial flutter (AFL) would facilitate a more complete understanding of its circuit. Such very high density mapping was performed with the Rhythmia mapping system using its 64 electrode basket catheter. METHODS AND RESULTS: Data were acquired from 13 patients in AFL. Functional anatomy of the right atrium (RA) was readily identified during mapping including the Crista Terminalis and Eustachian ridge. The leading edge of the activation wavefront was identified without interruption and its conduction velocity (CV) calculated. CV was not different at the cavotricuspid isthmus (CTI) compared to the remainder of the RA (1.02 vs. 1.03 m/s, p = 0.93). The sawtooth pattern of the surface EKG flutter waves were compared to the position of the dominant wavefront. The downslope of the surface EKG flutter waves represented on average, 73% ± 9% of the total flutter cycle length. During the downslope the activation wavefront travelled significantly further than during the upslope (182 ± 21 ms vs. 68 ± 29 ms, p < 0.0001) with no change in conduction velocity between the two phases (0.88 vs. 0.91 m/s, p = 0.79). CONCLUSION: CV at the CTI is not slower than other RA regions during typical AFL. The gradual downslope of the sawtooth EKG is not due to slow conduction at the CTI suggesting that success of ablation at this site relates to anatomical properties rather than presence of a "slow isthmus". This article is protected by copyright. All rights reserved.

Journal article

Shun-Shin MJ, Zheng S, Cole G, Howard J, Whinnett Z, Francis Det al., 2017, Implantable cardioverter defibrillators for primary prevention of death in left ventricular dysfunction with and without ischaemic heart disease: a meta-analysis of 8567 patients in the 11 trials, European Heart Journal, Vol: 38, Pages: 1738-1746, ISSN: 1522-9645

AimsPrimary prevention implantable cardioverter defibrillators (ICDs) are established therapy for reducing mortality in patients with left ventricular systolic dysfunction and ischaemic heart disease (IHD). However, their efficacy in patients without IHD has been controversial. We undertook a meta-analysis of the totality of the evidence.Methods We systematically identified all RCTs comparing ICD versus no ICD in primary prevention. Eligible RCTs were those that recruited patients with left ventricular dysfunction, reported all-cause mortality, and presented their results stratified by the presence of IHD (or recruited only those with or without). Our primary endpoint was all-cause mortality.ResultsWe identified 11 studies enrolling 8567 participants with left ventricular dysfunction, including 3128 patients without IHD and 5439 patients with IHD. In patients without IHD, ICD therapy reduced mortality by 24% (HR 0.76, 95% CI 0.64 to 0.90 p=0.001). In patients with IHD, ICD implantation (at a dedicated procedure), also reduced mortality by 24% (HR 0.76, 95% CI 0.60 to 0.96, p=0.02).ConclusionsUntil now, it has never been explicitly stated that the patients without IHD in COMPANION showed significant survival benefit from adding ICD therapy (to a background of CRT). Furthermore, even with only the trials before DANISH, meta-analysis shows reduced mortality. DANISH is consistent with these data.With a significant 24% mortality reduction in both aetiologies, it may no longer be necessaryto distinguish between them when deciding on primary prevention ICD implantation.

Journal article

Luther V, Sikkel M, Bennett N, Guerrero F, Leong K, Qureshi N, Ng FS, Hayat SA, Sohaib SMA, Malcolme-Lawes L, Lim E, Wright I, Koa-Wing M, Lefroy DC, Linton NWF, Whinnett Z, Kanagaratnam P, Davies W, Peters NS, Lim PBet al., 2017, Visualizing Localized Reentry With Ultra-High Density Mapping in Iatrogenic Atrial Tachycardia Beware Pseudo-Reentry, CIRCULATION-ARRHYTHMIA AND ELECTROPHYSIOLOGY, Vol: 10, ISSN: 1941-3149

Background—The activation pattern of localized reentry (LR) in atrial tachycardia remains incompletely understood. We used the ultra–high density Rhythmia mapping system to study activation patterns in LR.Methods and Results—LR was suggested by small rotatory activations (carousels) containing the full spectrum of the color-coded map. Twenty-three left-sided atrial tachycardias were mapped in 15 patients (age: 64±11 years). 16 253±9192 points were displayed per map, collected over 26±14 minutes. A total of 50 carousels were identified (median 2; quartiles 1–3 per map), although this represented LR in only n=7 out of 50 (14%): here, rotation occurred around a small area of scar (<0.03 mV; 12±6 mm diameter). In LR, electrograms along the carousel encompassed the full tachycardia cycle length, and surrounding activation moved away from the carousel in all directions. Ablating fractionated electrograms (117±18 ms; 44±13% of tachycardia cycle length) within the carousel interrupted the tachycardia in every LR case. All remaining carousels were pseudo-reentrant (n=43/50 [86%]) occurring in areas of wavefront collision (n=21; median 0.5; quartiles 0–2 per map) or as artifact because of annotation of noise or interpolation in areas of incomplete mapping (n=22; median 1, quartiles 0–2 per map). Pseudo-reentrant carousels were incorrectly ablated in 5 cases having been misinterpreted as LR.Conclusions—The activation pattern of LR is of small stable rotational activations (carousels), and this drove 30% (7/23) of our postablation atrial tachycardias. However, this appearance is most often pseudo-reentrant and must be differentiated by interpretation of electrograms in the candidate circuit and activation in the wider surrounding region.

Journal article

Jones S, Lumens J, Sohaib SMA, Finegold JA, Kanagaratnam P, Tanner M, Duncan E, Moore P, Leyva F, Frenneaux M, Mason M, Hughes AD, Francis D, Whinnett ZI, the BRAVO Investigators, on behalf of the BRAVO Investigatorset al., 2016, Cardiac Resynchronisation Therapy: mechanisms of action and scope for further improvement in cardiac function, Europace, Vol: 19, Pages: 1178-1186, ISSN: 1532-2092

BackgroundCardiac resynchronisation therapy(CRT) may exert its beneficial hemodynamic effect by improving ventricular synchrony and improving atrioventricular(AV) timing.Aims To establish the relative importance of the mechanisms through which CRT improves cardiac function and explore the potential for additional improvements with improved ventricular resynchronisation. Methods We performed simulations using the CircAdapt haemodynamic model and performed haemodynamic measurements while adjusting AV delay, at low and high heart rates, in 87 patients with CRT devices. We assessed QRS duration, presence of fusion and haemodynamic response.ResultsThe simulations suggest intrinsic PR interval and the magnitude of reduction in ventricular activation determine the relative importance of the mechanisms of benefit. For example, if PR interval is 201ms and LV activation time is reduced by 25ms (typical for current CRT methods) then AV delay optimisation is responsible for 69% of overall improvement. Reducing LV activation time by an additional 25ms produced an additional 2.6mmHg increase in BP (30% of effect size observed with current CRT).In the clinical population, ventricular fusion significantly shortened QRS duration (∆-27±23ms, P <0.001), and, improved SBP (mean 2.5 mmHg increase). Ventricular Fusion was present in 69% of patients, yet in 40% of patients with fusion, shortening AV delay (to a delay where fusion was not present) produced the optimal haemodynamic response.ConclusionsImproving LV preloading by shortening AV delay is an important mechanism through which cardiac function is improved with CRT. There is substantial scope for further improvement if methods for delivering more efficient ventricular resynchronisation can be developed.

Journal article

Luther V, Linton NW, Jamil-Copley S, Koa-Wing M, Lim PB, Qureshi N, Ng FS, Hayat S, Whinnett Z, Davies DW, Peters NS, Kanagaratnam Pet al., 2016, A prospective study of ripple mapping the post-infarct ventricular scar to guide substrate ablation for ventricular tachycardia, Circulation: Arrhythmia and Electrophysiology, Vol: 9, Pages: 1-12, ISSN: 1941-3084

BACKGROUND: Post-infarct ventricular tachycardia is associated with channels of surviving myocardium within scar characterized by fractionated and low-amplitude signals usually occurring late during sinus rhythm. Conventional automated algorithms for 3-dimensional electro-anatomic mapping cannot differentiate the delayed local signal of conduction within the scar from the initial far-field signal generated by surrounding healthy tissue. Ripple mapping displays every deflection of an electrogram, thereby providing fully informative activation sequences. We prospectively used CARTO-based ripple maps to identify conducting channels as a target for ablation. METHODS AND RESULTS: High-density bipolar left ventricular endocardial electrograms were collected using CARTO3v4 in sinus rhythm or ventricular pacing and reviewed for ripple mapping conducting channel identification. Fifteen consecutive patients (median age 68 years, left ventricular ejection fraction 30%) were studied (6 month preprocedural implantable cardioverter defibrillator therapies: median 19 ATP events [Q1-Q3=4-93] and 1 shock [Q1-Q3=0-3]). Scar (<1.5 mV) occupied a median 29% of the total surface area (median 540 points collected within scar). A median of 2 ripple mapping conducting channels were seen within each scar (length 60 mm; initial component 0.44 mV; delayed component 0.20 mV; conduction 55 cm/s). Ablation was performed along all identified ripple mapping conducting channels (median 18 lesions) and any presumed interconnected late-activating sites (median 6 lesions; Q1-Q3=2-12). The diastolic isthmus in ventricular tachycardia was mapped in 3 patients and colocated within the ripple mapping conducting channels identified. Ventricular tachycardia was noninducible in 85% of patients post ablation, and 71% remain free of ventricular tachycardia recurrence at 6-month median follow-up. CONCLUSIONS: Ripple mapping can be used to identify conduction channels within scar to guide functional substrate

Journal article

Leong KMW, Ng FS, Yao C, Yates S, Taraborrelli P, Linton NW, Whinnett Z, LeFroy D, Davies DW, Lim PB, Peters NS, Harding SE, Kanagaratnam P, Varnava Aet al., 2016, Contribution of Conduction and Repolarisation Abnormalities to the Type I Brugada Pattern: A Study Using Non-Invasive Electrocardiographic Imaging, Annual Conference of the British Cardiovascular Society (BCS) on Prediction and Prevention, Publisher: BMJ Publishing Group, Pages: A105-A106, ISSN: 1468-201X

Conference paper

Leong KMW, Chow J-J, Ng FS, Yates S, Wright I, Luther V, David L, Qureshi N, Koa-Wing M, Whinnett Z, Linton NW, Davies DW, Lim PB, Peters NS, Kanagaratnam P, Varnava Aet al., 2016, Risk Stratification in Hypertrophic Cardiomyopathy: Evaluation of the European Society of Cardiology Sudden Cardiac Death Risk Scoring System, Annual Conference of the British Cardiovascular Society (BCS) on Prediction and Prevention, Publisher: BMJ Publishing Group, Pages: A104-A105, ISSN: 1355-6037

Conference paper

Luther V, Linton NW, Jamil-Copley S, Koa-Wing M, Qureshi N, Ng F, Lim PB, Whinnett Z, Davies DW, Peters NS, Kanagaratnam Pet al., 2016, RIPPLE MAPPING THE VENTRICULAR SCAR: A NOVEL APPROACH TO SUBSTRATE ABLATION OF POST-INFARCT VENTRICULAR TACHYCARDIA TO PREVENT IMPLANTABLE DEFIBRILLATOR THERAPY, Annual Conference of the British-Cardiovascular-Society (BCS) on Prediction and Prevention, Publisher: BMJ PUBLISHING GROUP, Pages: A49-A50, ISSN: 1355-6037

Conference paper

Luther V, Linton NW, Koa-Wing M, Lim PB, Jamil-Copley S, Qureshi N, Ng FS, Hayat S, Whinnett Z, Davies DW, Peters NS, Kanagaratnam Pet al., 2016, A prospective study of ripple mapping in atrial tachycardias: a novel approach to interpreting activation in low-voltage areas, Circulation: Arrhythmia and Electrophysiology, Vol: 9, Pages: 1-13, ISSN: 1941-3084

BACKGROUND: Post ablation atrial tachycardias are characterized by low-voltage signals that challenge current mapping methods. Ripple mapping (RM) displays every electrogram deflection as a bar moving from the cardiac surface, resulting in the impression of propagating wavefronts when a series of bars move consecutively. RM displays fractionated signals in their entirety thereby helping to identify propagating activation in low-voltage areas from nonconducting tissue. We prospectively used RM to study tachycardia activation in the previously ablated left atrium.METHODS AND RESULTS: Patients referred for atrial tachycardia ablation underwent dense electroanatomic point collection using CARTO3v4. RM was played over a bipolar voltage map and used to determine the voltage "activation threshold" that differentiated functional low voltage from nonconducting areas for each map. Ablation was guided by RM, but operators could perform entrainment or review the isochronal activation map for diagnostic uncertainty. Twenty patients were studied. Median RM determined activation threshold was 0.3 mV (0.19-0.33), with nonconducting tissue covering 33±9% of the mapped surface. All tachycardias crossed an isthmus (median, 0.52 mV, 13 mm) bordered by nonconducting tissue (70%) or had a breakout source (median, 0.35 mV) moving away from nonconducting tissue (30%). In reentrant circuits (14/20) the path length was measured (87-202 mm), with 9 of 14 also supporting a bystander circuit (path lengths, 147-234 mm). In breakout tachycardias, splitting of wavefronts resulted in 2 to 4 incomplete circuits. RM-guided ablation interrupted the tachycardia in 19 of 20 cases with the first ablation set. CONCLUSIONS: RM helps to define activation through low-voltage regions and aids ablation of atrial tachycardias.

Journal article

Kim M-Y, Ng FS, Ariff B, Hanna GB, Whinnett Z, Kanagaratnam P, Tanner M, Lim PBet al., 2015, Extensive Intramural Esophageal Hematoma After Transesophageal Echocardiography During Atrial Fibrillation Ablation, CIRCULATION, Vol: 132, Pages: 1847-1849, ISSN: 0009-7322

Journal article

Sohaib SMA, Wright I, Lim E, Moore P, Lim PB, Koawing M, Lefroy DC, Lustgarten D, Linton NWF, Davies DW, Peters NS, Kanagaratnam P, Francis DP, Whinnett ZIet 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

Journal article

Dehbi H-M, Jones S, Sohaib SMA, Finegold JA, Siggers JH, Stegemann B, Whinnett ZI, Francis DPet al., 2015, A novel curve fitting method for AV optimisation of biventricular pacemakers, PHYSIOLOGICAL MEASUREMENT, Vol: 36, Pages: 1889-1900, ISSN: 0967-3334

Journal article

Raphael CE, Finegold JA, Barron AJ, Whinnett ZI, Mayet J, Linde C, Cleland JGF, Levy WC, Francis DPet al., 2015, The effect of duration of follow-up and presence of competing risk on lifespan-gain from implantable cardioverter defibrillator therapy: who benefits the most?, European Heart Journal, Vol: 36, Pages: 1676-1688, ISSN: 0195-668X

BackgroundIn at-risk patients with left ventricular dysfunction, implantable cardioverter defibrillators (ICDs) prolong life. Implantable cardioverter defibrillators are increasingly implanted for primary prevention and therefore into lower risk patients. Trial data have demonstrated the benefit of these devices but does not provide an estimate of potential lifespan-gain over longer time periods, e.g. a patient's lifespan.MethodsUsing data from landmark ICD trials, lifespan-gain was plotted against baseline annual mortality in the individual trials. Lifespan-gain was then extrapolated to a time-horizon of >20 years while adjusting for increasing ‘competing’ risk from ageing and non-sudden cardiac death (pump failure).ResultsAt 3 years, directly observed lifespan-gain was strongly dependent on baseline event rate (r = 0.94, P < 0.001). However, projecting beyond the duration of the trial, lifespan-gain increases rapidly and non-linearly with time. At 3 years, it averages 1.7 months, but by 10 years up to 9-fold more. Lifespan-gain over time horizons >20 years were greatest in lower risk patients (∼5 life-years for 5% baseline mortality, ∼2 life-years for 15% baseline mortality). Increased competing risks significantly reduce lifespan-gain from ICD implantation.ConclusionWhile high-risk patients may show the greatest short-term gain, the dramatic growth of lifespan-gain over time means that it is the lower risk patients, e.g. primary prevention ICD implantation, who gain the most life-years over their lifetime. Benefit is underestimated when only trial data are assessed as trials can only maintain randomization over limited periods. Lifespan-gain may be further increased through advances in ICD device programming.

Journal article

Sharp A, Sohaib A, Willson K, Mayet J, Hughes A, Kanagaratnam P, Whinnett Z, Kyriacou A, Francis Det al., 2015, SIGNAL-TO-NOISE RATIO DURING HAEMODYNAMIC OPTIMISATION OF AV DELAY IS IMPROVED MORE BY ATRIAL PACING THAN BY INCREASING HEART RATE, British-Cardiac-Society (BCS) Annual Conference on Hearts and Genes, Publisher: BMJ PUBLISHING GROUP, Pages: A25-A26, ISSN: 1355-6037

Conference paper

Luther V, Jamil-Copley S, Koa-Wing M, Shun-Shin M, Hayat S, Linton NW, Lim PB, Whinnett Z, Wright IJ, Lefroy D, Peters NS, Davies DW, Kanagaratnam Pet 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.

Journal article

Sohaib SM, Kyriacou A, Jones S, Manisty CH, Mayet J, Kanagaratnam P, Peters NS, Hughes AD, Whinnett ZI, Francis DPet al., 2015, Evidence that conflict regarding size of haemodynamic response to interventricular delay optimization of cardiac resynchronization therapy may arise from differences in how atrioventricular delay is kept constant., Europace, Vol: 17, ISSN: 1532-2092

AIMS: Whether adjusting interventricular (VV) delay changes haemodynamic efficacy of cardiac resynchronization therapy (CRT) is controversial, with conflicting results. This study addresses whether the convention for keeping atrioventricular (AV) delay constant during VV optimization might explain these conflicts. METHOD AND RESULTS: Twenty-two patients in sinus rhythm with existing CRT underwent VV optimization using non-invasive systolic blood pressure. Interventricular optimization was performed with four methods for keeping the AV delay constant: (i) atrium and left ventricle delay kept constant, (ii) atrium and right ventricle delay kept constant, (iii) time to the first-activated ventricle kept constant, and (iv) time to the second-activated ventricle kept constant. In 11 patients this was performed with AV delay of 120 ms, and in 11 at AV optimum. At AV 120 ms, time to the first ventricular lead (left or right) was the overwhelming determinant of haemodynamics (13.75 mmHg at ±80 ms, P < 0.001) with no significant effect of time to second lead (0.47 mmHg, P = 0.50), P < 0.001 for difference. At AV optimum, time to first ventricular lead again had a larger effect (5.03 mmHg, P < 0.001) than time to second (2.92 mmHg, P = 0.001), P = 0.02 for difference. CONCLUSION: Time to first ventricular activation is the overwhelming determinant of circulatory function, regardless of whether this is the left or right ventricular lead. If this is kept constant, the effect of changing time to the second ventricle is small or nil, and is not beneficial. In practice, it may be advisable to leave VV delay at zero. Specifying how AV delay is kept fixed might make future VV delay research more enlightening.

Journal article

Ploux S, Eschalier R, Whinnett ZI, Lumens J, Derval N, Sacher F, Hocini M, Jais P, Dubois R, Ritter P, Haissaguerre M, Wilkoff BL, Francis DP, Bordachar Pet al., 2015, Electrical dyssynchrony induced by biventricular pacing: Implications for patient selection and therapy improvement, HEART RHYTHM, Vol: 12, Pages: 782-791, ISSN: 1547-5271

Journal article

Sohaib SMA, Finegold JA, Nijjer SS, Hossain R, Linde C, Levy WC, Sutton R, Kanagaratnam P, Francis DP, Whinnett ZIet al., 2015, Opportunity to Increase Life Span in Narrow QRS Cardiac Resynchronization Therapy Recipients by Deactivating Ventricular Pacing Evidence From Randomized Controlled Trials, JACC-HEART FAILURE, Vol: 3, Pages: 327-336, ISSN: 2213-1779

Journal article

Finegold J, Bordachar P, Kyriacou A, Sohaib SMA, Kanagaratnam P, Ploux S, Lim B, Peters N, Davies W, Ritter P, Francis DP, Whinnett ZIet 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

Journal article

Jabbour RJ, Shun-Shin MJ, Finegold JA, Sohaib SMA, Cook C, Nijjer SS, Whinnett ZI, Manisty CH, Brugada J, Francis DPet al., 2015, Effect of Study Design on the Reported Effect of Cardiac Resynchronization Therapy (CRT) on Quantitative Physiological Measures: Stratified Meta-Analysis in Narrow-QRS Heart Failure and Implications for Planning Future Studies, JOURNAL OF THE AMERICAN HEART ASSOCIATION, Vol: 4, ISSN: 2047-9980

Journal article

Eschalier R, Ploux S, Lumens J, Whinnett Z, Varma N, Meillet V, Ritter P, Jais P, Haissaguerre M, Bordachar Pet al., 2015, Detailed analysis of ventricular activation sequences during right ventricular apical pacing and left bundle branch block and the potential implications for cardiac resynchronization therapy, HEART RHYTHM, Vol: 12, Pages: 137-143, ISSN: 1547-5271

Journal article

Koa-Wing M, Jamil-Copley S, Ariff B, Kojodjojo P, Lim PB, Whinnett Z, Rajakulendran S, Malhotra P, Lefroy D, Peters NS, Davies DW, Kanagaratnam Pet 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.

Journal article

Jones S, Shun-Shin MJ, Cole GD, Whinnett ZI, Francis DPet al., 2014, Iterative method for atrioventricular optimization of cardiac resynchronization therapy: is beauty only in the eye of the beholder? Reply, EUROPACE, Vol: 16, Pages: 1866-1866, ISSN: 1099-5129

Journal article

Sohaib SM, Jones S, Manoharan K, Francisco N, March K, Francis DP, Whinnett ZIet al., 2014, 55Testing the validity of electrogram based AV optimization schemes using real world patient data., Europace, Vol: 16 Suppl 3

Manufacturers have each implemented manufacturer specific methods for electrogram based optimization of AV delay in CRT devices. Agreement between manufacturer algorithms has never been formally tested. Where the algorithms are fully published and available, we tested agreement between different device based AV optimisation scheme, and compared this to the AV optimum selected using non-invasive haemodynamic optimisation.

Journal article

Luther V, Jamil-Copley S, Shun-Shin M, Koa-Wing M, Wright I, Hayat S, Linton N, Lim PB, Lefroy D, Whinnett Z, Davies DW, Peters NS, Kanagaratnam Pet 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.

Journal article

Jabbour R, Shun-Shin M, Finegold JA, Sohaib SMA, Cook C, Whinnett Z, Manisty C, Francis Det al., 2014, Meta-analysis identifying the source of conflict of differing reports of CRT patients with narrow QRS heart failure, Annual Meeting of the European-Society-of-Cardiology (ESC), Publisher: OXFORD UNIV PRESS, Pages: 167-167, ISSN: 0195-668X

Conference paper

Sohaib SMA, Jones S, Kyriacou A, Manisty C, Mayet J, Kanagaratnam P, Peters N, Hughes A, Whinnett Z, Francis Det 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

Journal article

Jabbour R, Shun-Shin M, Finegold J, Sohaib A, Cook C, Whinnett Z, Manisty C, Francis Det al., 2014, META-ANALYSIS IDENTIFYING THE SOURCE OF CONFLICT BETWEEN DIFFERENT TRIAL REPORTS ON THE EFFECT OF CRT IN HEART FAILURE WITH NARROW QRS COMPLEXES, HEART, Vol: 100, Pages: A23-A23, ISSN: 1355-6037

Journal article

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