3hrc Assignment Submission

Mapping and Ablation
31
Panoramic characterization of left atrial wavefront activation during human persistent af using a 3D non-contact mapping system

G. Lee

G. Lee

St Bartholomews Hosptial, London

R. Hunter

R. Hunter

St Bartholomews Hosptial, London

M. Lovell

M. Lovell

St Bartholomews Hosptial, London

M. Finlay

M. Finlay

St Bartholomews Hosptial, London

V. Sawhney

V. Sawhney

St Bartholomews Hosptial, London

W. Ullah

W. Ullah

St Bartholomews Hosptial, London

I. Diab

I. Diab

St Bartholomews Hosptial, London

M. Dhinoja

M. Dhinoja

St Bartholomews Hosptial, London

M. Earley

M. Earley

St Bartholomews Hosptial, London

S. Sporton

S. Sporton

St Bartholomews Hosptial, London

Abstract

Objectives: To characterize the nature of AF wavefront dynamics during human persistent AF using three-dimensional non-contact mapping.

Background: The relative importance of focal drivers, multiple wavelets, rotors and endo/epicardial circuits in the maintenance of human persistent AF remains unclear. High-density endocardial non-contact mapping allows global analysis of atrial activation and hence has the potential to clarify these mechanisms.

Methods: A 3D non-contact mapping system (Ensite 30000) was used to map the LA of patients with persistent AF. High-density virtual unipolar electrograms were recorded (7.5s) after intravenous adenosine and analyzed off-line. Only sites<40mm from the center of the non-contact array were analyzed. Iso-potential maps with a colour range representing voltage amplitude were used to determine activation patterns. A wavefront (WF) was defined as a discrete front of endocardial depolarization presenting as a region of negative polarity. Wavefronts patterns were classified into 3 subtypes: 1) planar WFs 2) rotors or 3) focal sources with centrifugal depolarization. For each WF formed we analyzed 1. The anatomical site of origin 2. The unipolar EGM morphology at the site of earliest endocardial breakthrough and 3. WF propagation patterns.

Results: AF mapping was performed in 15 patients with PerAF (median duration 36m) with a mean age of 52 ± 9 yrs and mean LA diameter of 46 ± 7mm. In the majority of patients, AF was characterized by highly unstable patterns of activation with various combinations of 1-2 propagating planar wavefronts alternating with focal activations, which constantly formed, extinguished and reformed in a dynamic process perpetuating AF. Stable reentry circuits and AF rotors were never seen. Planar WFs accounted for 67 ± 35% of activations and had a mean WF width of 28 ± 14mm and an average endocardial life span of 98 ± 86ms. Focal activations accounted for 29.7 ± 33.5% of activations and had an average lifespan of 75.6 ± 95ms (P = ns). Only 2 patients exhibited repetitive focal firing from a single extra-pulmonary source (ligament of Marshall & anterior LA wall). Regional analysis showed the most common anatomical sites for new WF generation were the PVs 33%, LA roof 23%, Anterior LA 15%, LAA 11% and posterior LA 8%. The most common unipolar electrogram morphology observed at the earliest endocardial site of origin of these new WFs was a QS pattern in 34%, rS in 29%, CFAE in 26%, QR in 7% and in Rs 4%. This suggests that new WFs originate from both the endocardial and epicardial surfaces of the LA.

Conclusion: PerAF is characterized by the formation of highly unstable WFs consisting of various combinations of planar WFs and focal activations. Unipolar EGM analysis suggests that these WFs originate from both the endocardial and epicardial surfaces of the LA. These findings have implications for the ablation of PerAF.

32
High accuracy unipolar local activation time assignment to facilitate dense multipolar electrode mapping

Abstract

Introduction: Multipolar electrode mapping (MEM) increases acquisition speed of atrial local activation time (LAT) maps. Since small errors in LAT assignment may have large effects on map appearance MEM is usually performed with bipolar electrogram recordings, which clearly indicate local activation and minimize far-field signals. Nevertheless, significant increases in map accuracy and resolution could be achieved by utilizing the greater tissue sampling density available from unipolar electrogram recordings. Therefore we present an alternative method of LAT assignment utilizing unipolar electrograms, which aims to improve LAT accuracy, reduce intra-observer variability and remove influence from ventricular far-field signals.

Methods: PentaRay unipolar electrograms (4kHz) were processed by zero-phase band-pass (5-250Hz) filtering the signal gradient and LAT was taken as the resulting maximum negative peak. This approach (fGrad) was tested on simulated (n = 20) and clinical electrograms (n = 80). For simulated data, reference activation time was the 0mV transmembrane potential time. For clinical data, mean activation time at adjacent electrodes was compared with the corresponding bipolar activation time, defined as the barycenter of a non-linear energy operator given by E(j) = x(j)^2-x(j + 1)*x(j-1). Four observers annotated all clinical electrograms.

Results: Examples of fGrad-processed unipolar electrograms are shown in the Figure. Simulated data showed fGrad to correlate well with cellular activation (absolute error 1.83 ± 1.61ms). Compared with conventional LAT assignment to clinical data, inter-observer variability was significantly reduced with fGrad (mean variance 0.08ms v 1.69ms, p<0.001) and fGrad provided a significantly more accurate LAT measurement (mean absolute error 1.18ms v 2.33ms, p<0.001). Taken as a proportion of total PentaRay catheter activation time, mean LAT variance was reduced from 5.00% to 0.23% by applying fGrad. In the bottom panel of the Figure, accurate rejection of ventricular far-field signals is demonstrated when fGrad-processing is used for automatic activation assignment.

Conclusion: fGrad is a fast and reliable method of unipolar LAT assignment which could facilitate high density unipolar activation mapping.

33
Ripple mapping improves the visualisation of atrial tachycardia activation sequences

S. Jamil-Copley

S. Jamil-Copley

Department of Cardiac Electrophysiology, Hammersmith Hospital Campus, Imperial College Healthcare NHS Trust and Imperial College, London

N. Linton

N. Linton

Department of Cardiac Electrophysiology, Hammersmith Hospital Campus, Imperial College Healthcare NHS Trust and Imperial College, London

M. Koa-Wing

M. Koa-Wing

Department of Cardiac Electrophysiology, Hammersmith Hospital Campus, Imperial College Healthcare NHS Trust and Imperial College, London

P.B. Lim

P.B. Lim

Department of Cardiac Electrophysiology, Hammersmith Hospital Campus, Imperial College Healthcare NHS Trust and Imperial College, London

S. Hayat

S. Hayat

Department of Cardiac Electrophysiology, Hammersmith Hospital Campus, Imperial College Healthcare NHS Trust and Imperial College, London

N. Qureshi

N. Qureshi

Department of Cardiac Electrophysiology, Hammersmith Hospital Campus, Imperial College Healthcare NHS Trust and Imperial College, London

Z. Whinnett

Z. Whinnett

Department of Cardiac Electrophysiology, Hammersmith Hospital Campus, Imperial College Healthcare NHS Trust and Imperial College, London

W. Davies

W. Davies

Department of Cardiac Electrophysiology, Hammersmith Hospital Campus, Imperial College Healthcare NHS Trust and Imperial College, London

N. Peters

N. Peters

Department of Cardiac Electrophysiology, Hammersmith Hospital Campus, Imperial College Healthcare NHS Trust and Imperial College, London

D. Francis

D. Francis

Department of Cardiac Electrophysiology, Hammersmith Hospital Campus, Imperial College Healthcare NHS Trust and Imperial College, London

P. Kanagaratnam

P. Kanagaratnam

Department of Cardiac Electrophysiology, Hammersmith Hospital Campus, Imperial College Healthcare NHS Trust and Imperial College, London

Abstract

Background: Electro-anatomic mapping (CARTO-XP) can diagnose atrial tachycardias (AT) and improved versions collect detailed anatomy (CARTO3) and multiple points simultaneously (MEM), but all are susceptible to annotation and interpolation errors. Ripple Mapping (RM) displays electrograms without annotation as dynamic bars, on the surface geometry, gated to a fiduciary time-point. We compared diagnostic accuracy of RM with electro-anatomic activation mapping.

Methods: Electro-anatomic maps of patients undergoing AT ablation were collected using different CARTO versions. RM and unannotated CARTO-XP maps were presented to experienced CARTO users with limited RM training but blinded to conventional EP data. The diagnostic accuracy using the two systems was compared and the causes of errors analysed.

Results: 20pts were studied with the diagnosis confirmed by entrainment and termination in 19/20. Analysing maps from 10pts, blinded assessors (n = 11) found that RM was superior (35/44 correctly diagnosed (80%)) to CARTO-XP(22/44 (50%) (p = 0.029)). Errors occurring with RM were due to difficulty interpreting areas of low point-density (162 ± 40pts/map) particularly in low voltage regions not displayed as scar. We therefore applied RM to CARTO3 cases (n = 5) with higher point-density collected (290 ± 73pts/map) and low voltage areas displayed as scar. All activation sequences were clearly visualised including dual-loop re-entry. Using MEM (n = 7) point-density was improved further (1115 ± 410pts/map) without increasing collection or annotation time.

Conclusion: Ripple Mapping improves visualisation of AT activation mechanism resulting in greater diagnostic accuracy compared to conventional activation mapping1.

34
Non-invasive electrocardiographic mapping to guide ablation of outflow tract ventricular arrhythmias: pre-procedural localisation accuracy

S. Jamil-Copley

S. Jamil-Copley

1

Department of Cardiac Electrophysiology, Hammersmith Hospital Campus, Imperial College Healthcare NHS Trust and Imperial College, London

B. Ryan

B. Ryan

2

Cardioinsight Technologies, Cleveland, Ohio

P. Kojodjojo

P. Kojodjojo

1

Department of Cardiac Electrophysiology, Hammersmith Hospital Campus, Imperial College Healthcare NHS Trust and Imperial College, London

N. Qureshi

N. Qureshi

1

Department of Cardiac Electrophysiology, Hammersmith Hospital Campus, Imperial College Healthcare NHS Trust and Imperial College, London

M. Koa-Wing

M. Koa-Wing

1

Department of Cardiac Electrophysiology, Hammersmith Hospital Campus, Imperial College Healthcare NHS Trust and Imperial College, London

S. Hayat

S. Hayat

1

Department of Cardiac Electrophysiology, Hammersmith Hospital Campus, Imperial College Healthcare NHS Trust and Imperial College, London

A. Kyriacou

A. Kyriacou

1

Department of Cardiac Electrophysiology, Hammersmith Hospital Campus, Imperial College Healthcare NHS Trust and Imperial College, London

B. Sandler

B. Sandler

1

Department of Cardiac Electrophysiology, Hammersmith Hospital Campus, Imperial College Healthcare NHS Trust and Imperial College, London

A. Sohaib

A. Sohaib

1

Department of Cardiac Electrophysiology, Hammersmith Hospital Campus, Imperial College Healthcare NHS Trust and Imperial College, London

I. Wright

I. Wright

1

Department of Cardiac Electrophysiology, Hammersmith Hospital Campus, Imperial College Healthcare NHS Trust and Imperial College, London

W. Davies

W. Davies

1

Department of Cardiac Electrophysiology, Hammersmith Hospital Campus, Imperial College Healthcare NHS Trust and Imperial College, London

N. Peters

N. Peters

1

Department of Cardiac Electrophysiology, Hammersmith Hospital Campus, Imperial College Healthcare NHS Trust and Imperial College, London

Z. Whinnett

Z. Whinnett

1

Department of Cardiac Electrophysiology, Hammersmith Hospital Campus, Imperial College Healthcare NHS Trust and Imperial College, London

P. Kanagaratnam

P. Kanagaratnam

1

Department of Cardiac Electrophysiology, Hammersmith Hospital Campus, Imperial College Healthcare NHS Trust and Imperial College, London

P.B. Lim

P.B. Lim

1

Department of Cardiac Electrophysiology, Hammersmith Hospital Campus, Imperial College Healthcare NHS Trust and Imperial College, London

Abstract

Background: Catheter ablation within these complex anatomical structures can be effective ineliminating symptoms and reversing PVC induced cardiomyopathy but there remain significant limitations to current ablation techniques, including poor spatial resolution of pace-mapping, inaccurate ECG-based localisation of VT origin and, especiallylimiting, lack of spontaneous ectopy rendering activation mapping ineffective.

This study aims to prospectively assess the performance of non-invasive electrocardiographic mapping (ECM) in the pre- and peri-procedural localisation of OTVT origin to guide ablation and compare the accuracy of ECM to published ECG algorithms.

Methods: Patients with symptomatic OTVT/PVCs undergoing clinically-indicated ablation were recruited. OTVT/PVC origin was mapped pre-procedurally using ECM and 3 published ECG algorithms applied to the12-lead ECG by 3 blinded electrophysiologists. Ablation was guided by ECM and conventional manoeuvres. The OTVT/PVC origin was definedas the site where ablation caused arrhythmia suppression. Acute success was defined as abolition of ectopy following ablation. Medium term success was defined as abolition of symptoms and reduction of PVC<1,000/day documented on Holter monitoring within 6 months.

Results: Sixteen patients (5males,mean age 49 ± 15 years) were recruited. Six patients had previously undergone EPS; three havin gun successful ablation. ECM successfully identified OTVT/PVC origin, including sub-localising within the RVOT (11) and LVOT (6) in all patients [1 postero-septal RVOT, 6 antero-septal RVOT, 3 mid-septal RVOT, 1 postero-lateral RVOT, 3 left coronary cusp (LCC) and 2 aorto-mitralcontinuity (AMC) sites], with acute success achieved in 100% cases, and mediumterm success achieved in 15/16 patients. The ECG algorithms identified the correct chamber of origin in 63-94% of patients and sub-localised within the RVOT (septum vs free-wall) in 27-82%.

PVC burden reduced from 15278 ± 19463 to 149 ± 243 PVCs (p = 0.001).

Conclusion: ECM can accurately identify OTVT/PVC origin in the left and right ventricle pre- and peri-procedurally to guide catheter ablation with an accuracy superior to published ECG algorithms.

35
Low voltage areas in atrial fibrillation do not correlate to LGE-MRI defined scar in patients with persistent atrial fibrillation

W. Bai

W. Bai

1

Imperial College, London

B. Ariff

B. Ariff

2

Imperial College Healthcare NHS Trust, London

C. Monro

C. Monro

3

St Jude Medical, St Paul

S. Kim

S. Kim

3

St Jude Medical, St Paul

S. Jamil-Copley

S. Jamil-Copley

2

Imperial College Healthcare NHS Trust, London

S. Hayat

S. Hayat

2

Imperial College Healthcare NHS Trust, London

M. Kao-Wing

M. Kao-Wing

2

Imperial College Healthcare NHS Trust, London

A. Kyriacou

A. Kyriacou

2

Imperial College Healthcare NHS Trust, London

B. Sandler

B. Sandler

2

Imperial College Healthcare NHS Trust, London

N.S. Fu

N.S. Fu

2

Imperial College Healthcare NHS Trust, London

P. Kanagaratnam

P. Kanagaratnam

2

Imperial College Healthcare NHS Trust, London

Z. Whinnett

Z. Whinnett

2

Imperial College Healthcare NHS Trust, London

D.W. Davies

D.W. Davies

2

Imperial College Healthcare NHS Trust, London

D. Lefroy

D. Lefroy

2

Imperial College Healthcare NHS Trust, London

N.S. Peters

N.S. Peters

2

Imperial College Healthcare NHS Trust, London

P.B. Lim

P.B. Lim

2

Imperial College Healthcare NHS Trust, London

Abstract

Introduction: Late-gadolinium enhancement (LGE) cardiac magnetic resonance imaging (CMR) can detect pre-existing left atrial (LA) scar. Low voltage areas mapped in sinus rhythm (SR) have been shown to correlate with LGE-defined scar. We studied LGE-defined LA scar and the corresponding voltage in AF.

Methods: Ten patients with persistent AF underwent LGE-CMR prior to their ablation to obtain LA scar maps using our previously described validated automated method. Bipolar voltage mapping was performed in AF (point density 3.25 ± 1.1/cm2) and low voltage electrograms (LVE) were defined as <0.1mV. LA scar maps were registered with the LA geometry and areas with LGE >3SD above the mean blood pool intensity (LGE-scar) were outlined. Voltage maps were registered to LA scar map to identify overlapping segments.

Results: LGE-scar was present in all patients, corresponding to an area of 17.3± 13.9cm2 accounting for 16.6 ± 13.0% of the total LA surface area. LVE accounted for 31.2 ± 31.3% of the total LA surface area. There was little correlation between areas of LGE-scar and LVE, with the area of overlap being only 3.0 ± 2.6 cm2 corresponding to 2.8 ± 2.5% of the total LA surface area. 3,360 points were exported and no significant correlation (Pearson's) was found between the bipolar voltage and intensity of LGE at its corresponding LA surface point at the Bonferroni corrected significance threshold p<0.05/10. There was no correlation between voltages and LGE intensity levels from SD 0 to 3.

Conclusions: Unlike in SR, LA endocardial voltages in AF do not correlate to LGE-defined LA scar in patients with persistent AF. This may reflect a distinct electrophysiological phenomenon as a result of functional electrical changes in AF.

36
Atrial tachyarrhythmia in adults with tetralogy of fallot – patient characteristics and successful experience with radiofrequency ablation in a single UK congenital cardiac centre

M.J. Ryan

M.J. Ryan

1

The Heart Hospital, University College London Hospitals NHS Foundation Trust, London

V.A. Ezzat

V.A. Ezzat

1

The Heart Hospital, University College London Hospitals NHS Foundation Trust, London

J. O'Leary

J. O'Leary

1

The Heart Hospital, University College London Hospitals NHS Foundation Trust, London

C. Bull

C. Bull

2

Great Ormond Street Hospital for Children NHS foundation Trust, London

Image: Focal left atrial tachycardia in a patient with previous pulmonary vein isolation for paroxysmal AF.

Image: Focal left atrial tachycardia in a patient with previous pulmonary vein isolation for paroxysmal AF.

Essay on Understanding Organisations and the Role of Human Resources

1903 WordsJan 14th, 20138 Pages

CIPD Assessment Report – Foundation (AR1) To be completed by candidate Centre name: | City of Glasgow College | Candidate name: | Allan Davidson | | CIPD Membership/ registration No: | | | | Qualification title: | Certificate in Human Resource Practice | Unit title(s): | Understanding Organisations and the Role of Human Resources | Unit code(s): | | Assessment activity (and assignment title if applicable) and the learning outcomes addresses: | Write a report on the HR Map | Date due for assessment: | 04 December 2012 | Extension request date | | | | Extension granted | Y/N | Actual date evidence submitted: | | Revised due date | | Candidate declaration: | * I confirm that the…show more content…

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