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THE UTILITY OF A NOVEL RAPID HIGH-RESOLUTION MAPPING SYSTEM IN THE CATHETER ABLATION OF ARRHYTHMIAS - AN
INITIAL HUMAN EXPERIENCE OF MAPPING THE ATRIA AND THE LEFT VENTRICLE
SHORT TITLE: CLINICAL UTILITY OF RAPID HIGH-RESOLUTION MAPPING
Lilian Mantziari MD PhD, Charles Butcher MRCP, Andrianos Kontogeorgis MRCP PhD, Sandeep
Panikker MBBS MRCP, Karine Roy MD, Vias Markides MD FRCP, Tom Wong MD FRCP
Royal Brompton and Harefield NHS Trust, London UK
Address for correspondence
Dr. Tom Wong, MD, FRCP
Heart Rhythm Centre, NIHR Cardiovascular Biomedical Research Unit, Institute of Cardiovascular
Medicine and Science.
The Royal Brompton and Harefield NHS Foundation Trust
Imperial College
Sydney Street, London SW3 6NP, United Kingdom
Email: [email protected]
Phone: +44 20 7351 8619
Fax: +44 20 7351 8629
Total word count: 4,447
Disclosures
LM, AK, KR, VM and TW none declared. CB is supported by a Boston Scientific investigator lead
research grant. SP is supported by a Boston Scientific research grant.
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Abstract
Objectives: To assess the clinical efficacy, safety and clinical utility of a novel electroanatomical mapping
system.
Background: A new mapping system, capable of rapidly acquiring detailed maps based on automatic
annotation of thousands of points was recently released for clinical use. This is the first description of it’s
utility in humans.
Methods: The first consecutive 20 cases (7 atrial tachycardia, 8 atrial fibrillation, 3 ventricular tachycardia
and 2 ventricular ectopic beat ablations) are analysed. The system (Rhythmia, Boston Scientific) uses a
bidirectional deflectable basket catheter with 64 closely spaced mini-electrodes. It automatically accepts
and annotates electrograms when a number of predefined criteria are met.
Results: Thirty right atrial maps were acquired in 11(4-15) min, consisting of 7220(3467-10947) points, 22
left atrial maps in 11(6-19) min, consisting of 7818(4379-12262) points and 10 left ventricular maps in
37(14-43) min, consisting of 8709(2605-15514) points. The mini-basket catheter could reach all areas of
interest without deflectable sheaths. No embolic events, bleeding complications or endocardial structure
damage were observed. Correction of the automatic annotation was performed in 0.02% of points in 4/62
maps. The system revealed re-entry circuits of atrial tachyarrhythmias, identified gaps on linear lesions,
identified and correctly annotated the clinical ventricular ectopic beats and channels of slow conduction
within ventricular scar.
Conclusions: The novel automatic mapping system was rapid, safe and efficacious in mapping a variety of
cardiac arrhythmias in humans. Further clinical research is needed to optimise its use in the ablation of
complex arrhythmias.
Key words: electroanatomical mapping system, high-resolution mapping, atrial tachycardia, atrial
fibrillation, ventricular tachycardia
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Condensed abstract
This is a single centre prospective study of the initial clinical experience in mapping the atria and the left
ventricle using a novel rapid high-resolution electroanatomical mapping system and a mini-basket catheter.
A total of 62 maps were created and analysed in 20 patients. The system was found to be efficacious and
safe in mapping a variety of atrial and ventricular tachyarrhythmias in humans.
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Abbreviations
AF=Atrial fibrillation
AT=Atrial tachycardia
CL=Cycle length
CS=Coronary sinus
LA=Left atrium/atrial
LV=Left ventricle
RA=Right atrium/atrial
RV=Right ventricle
VEs=Ventricular ectopics
VT=Ventricular tachycardia
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Introduction
The widely available 3-dimensional electroanatomical mapping systems use point-by-point acquisition of
electrograms from a roving catheter with or without multi-electrode mapping capability and usually require
extensive manual re-annotation (1,2). A novel mapping system (Rhythmia, Boston Scientific) has recently
become clinically available. This system is paired to a mini-basket array catheter with 64 mini-electrodes
(IntellaMap Orion, Boston Scientific) and is capable of acquiring and automatically annotating thousands of
points. This system has been shown to rapidly obtain high-resolution maps in canine and swine models with
no need for additional manual annotation, (3,4) however, to our knowledge, to date there is no report on the
utility of this system in humans. This paper describes the initial experience using the Rhythmia system and
the mini-basket catheter, focusing on the safety, feasibility and efficacy in mapping the atria and the LV in
humans.
Methods
Patients
We studied the first 20 consecutive electrophysiologic procedures using the Rhythmia mapping system at
our institution during the first three months of clinical availability of the system and catheter. A detailed
description of the cases is shown in table 1. All patients were adults (age 39-85), 7 patients had structurally
normal heart, 9 patients had heart failure and 4 had adult congenital heart disease. Fourteen patients were
admitted electively for procedures and 6 patients required an urgent ablation. Written informed consent
was obtained in all cases as per standard practice. Patient and procedural data were prospectively collected.
Procedures
All procedures were performed by two experienced operators. AT, AF and VT ablations were performed
under general anaesthesia and a transoesophageal echocardiogram was performed to exclude evidence of
thrombus and to guide the transseptal puncture. Two cases of ventricular ectopy (VE) ablation were
performed under sedation to avoid suppression of the ectopy. AF and AT ablations were performed on
uninterrupted warfarin with a therapeutic international normalised ratio on the day of the procedure. If a
non-vitamin K anticoagulant was used, this was discontinued 24-36 hours before the procedure according
to local guidelines. Antiarrhythmic medications were discontinued for 5 half-lives (excluding AF cases and
urgent cases).
Mapping system and mini basket multi-electrode catheter
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The Rhythmia mapping system is a 3D electroanatomical mapping platform that uses a hybrid location
technology that combines impedance and magnetic location. The magnetic field is generated by a
localisation generator positioned under the catheter lab table and is capable of locating the magnetically
tracked catheters with an accuracy of ≤1mm. The impedance location technology is used to track catheters
that are not equipped with a magnetic sensor. The system then maps the impedance field measurements to
the magnetic location coordinates and creates an impedance field map. This map is used to enhance the
accuracy of the impedance location. The Orion catheter is a bidirectional deflectable, multi-electrode, mini-
basket mapping catheter (Figure 1). Its maximum shaft diameter is 8.5F and is advanced into cardiac
chambers via 9F sheaths. The catheter can acquire points at variable degrees of deployment from
undeployed (3mm) to fully deployed (22mm).
Map acquisition
The Orion catheter was gently manipulated inside the chamber of interest and automatically acquired
points with every accepted beat. Criteria used for beat acceptance were a) stable cycle length, b) stable
timing difference between two reference electrodes, c) respiration gating, d) stable catheter location e)
stability of catheter signal compared to adjacent points and f) tracking quality. Mapping during AF was
achieved by enabling only the criteria c, d and f. For mapping of VEs and VT, an additional criterion of
correlation to a reference surface ECG QRS morphology was applied.
Time and voltage maps
The setup of the mapping window was automatic. The system calculated the mean cycle length of the
rhythm over 10 seconds and consequently set 100% of cycle length equally before and after the timing
reference electrode (usually one of the coronary sinus (CS) electrograms, or the QRS of one of the surface
ECG leads for ventricular rhythms). The final maps showed the activation propagation rather that the
“early” and “late” points. The mapping window could be moved anytime during or after the completion of
the map by manually dragging its ends on the screen using the mouse in order to focus on relevant parts of
the cycle length, such as the diastolic part during VT or to exclude non relevant electrograms such as the
QRS during AT (supplemental Figure 1).
For the bipolar time maps, the timing of the electrodes was based on the time difference between the
maximum amplitude of the bipolar electrogram and the first reference electrode (timing reference). For
electrograms with more than one potentials, the system selected the potential that best matched the timing
of the surrounding electrograms. For unipolar time maps, the timing was based on the most negative dV/dT
around the timing of the max bipolar signal. The bipolar and unipolar voltage maps were based on the
difference between the maximum and minimum peak of the signal. Noise level and complete electrical
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silence were considered as < 0.03mV, and low voltage areas were detected between 0.03mV and 0.5mV in
the atria and 0.03mV and 1.5mV in the ventricles.
Geometry
The geometry of the cardiac chambers was gradually acquired with every accepted beat based on the
location of the outermost electrodes of the basket catheter. For all cases, the system was programmed to
select and include in the map only electrograms up to 2-4 mm from the surface geometry.
Statistical analysis
Normality of distribution was tested with the Kolmogorov Smirnov test. All variables were non-normally
distributed and were reported as median and interquartile range (25th-75th percentile). The Stata software
version 13 (Stata corp Texas, USA) was used for the statistical analysis. The data were log transformed to
conform to a log normal distribution. In order to compare the time required for mapping various cardiac
chambers, as well as the number of accepted beats per type of chamber and number of electorgrams, whilst
accounting for clustering of chambers within patients we used linear mixed models analysis. A p<0.05 was
considered statistically significant.
Results
We present data from the first 20 consecutive procedures (Table 1). Seven patients with ATs, 8 patients
undergoing ablation for AF, and 5 patients with VT or VEs ablation were studied. A total of 62 high-
resolution maps were acquired with the mini-basket mapping catheter (Table 2). The LV maps took longer
to acquire (p<0.0001) compared to the RA and LA maps but there was no significant difference in accepted
beats and electrograms acquired among the chambers mapped.
Catheter manipulation and reach
The right femoral vein was used to advance the basket catheter in the atria. For RA mapping, a short 9
French sheath was used for 28 maps and a long, fixed curve sheath used for 2 maps in patients with a very
dilated RA. To map the LA, 9 French fixed-curve long sheaths (Mullins, Cook Medical Inc., Bloomington, IN,
USA) were used and allowed the basket catheter to reach all areas of interest in all cases. The LV was
mapped via both the transaortic and transseptal approach in 3 cases, by the transseptal approach alone in 1
case and by transaortic approach alone in 1 case with dextrocardia and surgically repaired atrial septal
defect. All operators that used the catheter reported ease of manipulation in the RA and LA. There were no
areas that the catheter could not reach and it could easily be advanced in the coronary sinus and the
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pulmonary veins. Mapping of the left ventricle was also feasible in all cases. An example of a full LV map is
shown in figure 2B.
Safety
The mini-basket catheter was meticulously flushed and inserted to the cardiac chambers after an activated
clotting time≥300 sec was achieved and maintained with boluses of intravenous heparin administration and
was irrigated with heparinised normal saline solution (1U/ml) at a rate of 1ml/minute throughout the
procedure. There were no embolic complications, including stroke or systemic embolism. All catheters were
checked and found to be free from any visible thrombus at the end of the procedure. There were no bleeding
complications or pericardial effusions. When during atrial mapping the catheter inadvertently entered the
right or the left ventricle, it was easily pulled back with no events of entrapment by the atrio-ventricular
valves or their subvalvular apparatus. Mapping of the LV did not affect the aortic or mitral valve function as
shown on post procedure echocardiogram. In 4 cases we used the transaortic approach to the left ventricle
with no thromboembolic complications or evidence of damage to the aortic root, the aortic valve or the
coronary arteries. In case 17 the patient had a previous Ross procedure for bicuspid aortic valve with a
pulmonary valve autograft in the place of the aortic valve. The retrograde approach and the LV mapping
were also uncomplicated in this case.
Accuracy of maps
The acquired maps showed highly detailed endocardial electrical activation. In the majority of cases manual
annotation was not necessary. In only 4 out of 62 maps manual annotation was performed in 16 out of
70862 points (0.02%). The main reasons for incorrect annotation were far field ventricular electrograms
around the valve areas and artefacts, however all points with incorrect annotation were easy to identify on
the high density map as areas of inconsistent colour coding to the adjacent areas (Figure 2). In atrial voltage
maps the threshold for the scar was reduced to 0.5-0.05 mV and in some cases, reduction to 0.25mV was
applied in order to facilitate the identification of gaps in linear lesions (Figure 3). In LV voltage maps the
standard cut-off of <1.5mV was applied but when the lower voltage cut-off was set to 0.2 mV, isthmuses of
slow conduction within scar areas were revealed. Three-dimensional basket and other catheter localisation
was always in keeping with the fluoroscopic findings and highly internally consistent.
Mapping of specific arrhythmias
Typical atrial flutter was used as a known arrhythmia substrate to validate the system. An example is
illustrated in Figure 3 and Video 1. Standard Pulmonary vein isolation with wide area circumferential
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ablation and additional activation/voltage maps of the LA before and after ablation was performed in
patients with AF (n=8) (Supplemental Figure 2). The patients with persistent AF had also additional
ablations (see table 2 for details). Post ablation, 12 maps of the LA were acquired in 8.0 (6.2-14.3) minutes,
consisting of 7818 (4891-19351) points, in order to assess entry block into pulmonary veins, assess the
linear lesions or map an AT. Following persistent AF ablation 5 gaps on linear lesions were identified and
ablated successfully on the site indicated by the system (Figure 4,). Two cases of macro re-entrant AT in
patients with congenital heart disease were studied and gaps on previous lesions and/or atriotomy scars
were identified as the isthmuses of slow conduction (Supplemental Figure 3), followed by successful
ablation (no inducibility of tachycardias). In total 9 macro re-entry ATs were mapped. The system mapped
100% of cycle length of 8 ATs. In one case of short lasting AT the system was able to map 69% of the cycle
length.
VEs were mapped and ablated in 2 patients. In both cases the system created a template to the clinical VE
and could accurately identify the clinical VE, accept the relevant beat, and annotate the signal automatically
(Supplemental Figure 4).
Three patients with sustained monomorphic VT were studied (Cases 16, 17, 18). The LV was mapped via the
transseptal (n=2) and the transaortic (n=3) approach. Mapping during VT was performed in cases 16 and
17. The system created the maps using a mapping window equal to the full cycle length of the tachycardia.
Two macro re-entry VTs were mapped in case 17, (100% of CL mapped) and one possible macro re-entry
VT was mapped in case 16 (42% of CL was mapped). We observed that mapping the full CL of the VT could
result in errors in automatic annotation because the system annotates the largest electrogram within the
mapping window and this can be either the local diastolic electrogram or the far field systolic electrogram,
whichever is larger (see example in Figure 5A). To avoid this in case 16 we changed the mapping window in
retrospect to focus on the diastolic part of the VT. This revealed a figure-of-8 re-entry VT in the infero-basal
LV wall with corresponding diastolic potentials at the entrance and presystolic electrograms at the exit. A
substrate map of the LV was performed in sinus rhythm. The voltage threshold for scar was set to 0.2-
1.5mV, to reveal additional channels of low voltage within the scar (Figure 5, Video 2)).
Discussion
To our knowledge, this is the first description of the initial clinical experience of a novel rapid high-
resolution mapping system in a variety of arrhythmias and substrates, including patients with acquired and
congenital heart disease. In brief, the system platform was user friendly and provided clear and accurate
localisation of catheters, geometry of cardiac chambers and low noise electrograms. The main advantages
of the system were a) the high-resolution mapping of both activation timing and voltage information b) the
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short time required to acquire the maps c) the accurate automatic annotation and d) the ability to change
the mapping window in retrospect.
The mini-basket catheter does not require a balloon to be deployed or additional stiff wire and sheath in
order to be positioned as other basket catheters do (5,6). It could be easily manipulated, deployed in various
degrees from zero to maximum and advanced in cardiac chambers, including pulmonary veins
(Supplemental Figure 2) and the right and left atrial appendages (Figure 4B) with no events of cardiac
perforation, valve damage, air embolism or visible clot formation. Additionally, the mini-basket catheter
benefits from very closely spaced electrodes and acquisition of contact electrograms. The obvious
disadvantage of high-resolution regional mapping is the need for sequential data acquisition at multiple
sites.
The maps we acquired in this cohort consisted of thousands of points acquired within a few minutes.
Mapping with previously available contact multipolar catheters usually can create maps with a total of a few
hundreds of points that require manual annotation in order to be meaningful (1,2). Previously, Nakagawa et
al calculated the mean resolution of the maps that were automatically acquired with this system to be 2.6
mm (1.8-4.4 mm) (3). The detailed maps may have the potential benefit of revealing valuable information
with regard to the substrate.
We used the system in a variety of cardiac arrhythmias in order to explore its efficacy and potential future
utility. In this initial experience we observed that this system could accurately demonstrate gaps along the
linear lesions (Figures 3 and 4), verifying the results of Nakagawa et al in the experimental model in canines
(3). Limited ablation on the site of the gap shown by the system led to tachycardia termination and/or
achievement of block. The atrial voltage maps might also provide useful information for persistent AF
ablation (7). The detail that this system can record with regard to the direction and velocity of endocardial
activation may be useful to map AF in the future but this warrants further investigation.
In VT ablation, our initial experience showed that the basket catheter can be used to map the LV via both the
transseptal and retrograde approach and can reach all areas inside the LV, although manipulation was a
little more challenging because of the ventricular myocardial trabeculations and subvalvular apparatus. The
longer time to acquire the LV maps was mainly attributed to the low frequency of VEs in two cases. The
automated QRS matching to the clinical VE or VT was accurate in all cases and the system was capable of
rejecting the non-clinical ectopic beats and correctly annotating the clinical ectopics.
The low noise mini-electrodes can record signals of very low voltage and it’s not clear whether this impacts
on the scar cut off values. It was previously shown that endocardial areas with bipolar voltage <1.5mV
correspond to myocardial scar (8,9). Preclinical evaluation of this system in a swine model of ischemic scar
showed that the same cut off of <1.5mV correlated with scar on cardiac delayed-enhancement magnetic
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resonance imaging (MRI) (10). A pre-clinical study in dogs also showed that the size and location of scar
mapped on electroanatomical maps acquired with this system were highly correlated with scar observed in
cardiac MRI(11). However, looking further into scar at lower voltages may help to reveal channels of slow
conduction and facilitate the substrate mapping and ablation of VT.
One unique characteristic of this mapping system was that we could easily change the mapping window
retrospectively. By excluding the QRS and moving the window of interest on the diastolic part of the CL
during VT enabled the mapping of the local activation along the critical isthmus of the VT that occurs during
diastole (12,13). This feature requires further validation in a larger study.
The mean procedure duration and fluoroscopy time of the studies presented in this paper seems to be no
shorter than usual for our institution (14), but this is expected as we used the system to explore its potential
and future clinical use and there was a learning curve for the operators and cardiac physiologists, therefore
a direct comparison to previous standard clinical practice was not attempted.
Limitations
A small number of patients are included in this paper and a heterogeneous group of cases is described. A
comparison to other mapping systems was not attempted at this stage due to catheter/system
incompatibilities and to allow for a learning curve. The current report is a description of sequential cases
rather than being based on an experimental protocol and, on clinical grounds, there was no opportunity to
map the RV in these cases, although we would anticipate very simple manipulation in the RV and its outflow
tract based on experience in other chambers. Similarly we did not use the system to perform epicardial
mapping, where additional complexities may be encountered. We could not verify the accuracy of the
voltage maps because no scar information from cardiac MRI was available. The system uses a hybrid
magnetic and impedance location technology. Although no discrepancy was noted between the system and
the fluoroscopic location of the catheters this has not been formally validated.
Conclusions
The novel rapid automatic mapping system was used in a variety of human cardiac arrhythmias and proved
to be both safe and efficacious. We were able to acquire detailed geometry of the cardiac chambers and
high-resolution activation and voltage information based on automatic annotation. The system was capable
of mapping macro-re entry tachycardias and assessing linear lesions with detailed information on slow
conduction isthmuses, guiding the ablation for AF, creating detailed maps of the left ventricle during sinus
rhythm or VT and successfully selecting and automatically annotating the clinical ventricular ectopic beats.
Its optimal use in specific tachycardia mapping and ablation warrants further research.
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Competencies in Medical Knowledge
This novel high-resolution mapping system can rapidly acquire thousands of points and create very detailed
voltage and activation maps without the need for manual annotation. Our first clinical observations have
shown that the system is safe and efficacious in mapping the atria and the left ventricle in a variety of
arrhythmia substrates with the advantages of being automatic and rapid. In addition it offers the ability to
the operator to review the maps and change the mapping window in retrospect in order to focus on areas of
interest such as the diastolic part of the cycle length during ventricular tachycardia.
Translational Outlook
The characteristics of this novel system may improve our understanding of the mechanisms of
complex arrhythmias and enhance the ablation outcomes but this warrants further clinical research.
Acknowledgements
We would like to thank Dr Kostas Dimopoulos and Mr Winston Banya for their assistance with the statistical
analysis.
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References
1. Weerasooriya R, Jaïs P, Wright M et al. Catheter ablation of atrial tachycardia following atrial fibrillation ablation. J Cardiovasc Electrophysiol. 2009 Jul;20(7):833–8.
2. Jones DG, McCready JW, Kaba R a, et al.. A multi-purpose spiral high-density mapping catheter: initial clinical experience in complex atrial arrhythmias. J Interv Card Electrophysiol. 2011 Sep;31(3):225–35.
3. Nakagawa H, Ikeda A, Sharma T, Lazzara R, Jackman WM. Rapid high resolution electroanatomical mapping: evaluation of a new system in a canine atrial linear lesion model. Circ Arrhythm Electrophysiol. 2012 Apr;5(2):417–24.
4. Ptaszek LM, Chalhoub F, Perna F,et al.. Rapid acquisition of high-resolution electroanatomical maps using a novel multielectrode mapping system. J Interv Card Electrophysiol. 2013 Apr;36(3):233–42.
5. Tai C-T, Liu T-Y, Lee P-C, Lin Y-J, Chang M-S, Chen S-A. Non-contact mapping to guide radiofrequency ablation of atypical right atrial flutter. J Am Coll Cardiol. 2004 Sep 1;44(5):1080–6.
6. Arentz T, von Rosenthal J, Blum T,et al. Feasibility and safety of pulmonary vein isolation using a new mapping and navigation system in patients with refractory atrial fibrillation. Circulation. 2003 Nov 18;108(20):2484–90.
7. Jadidi AS, Duncan E, Miyazaki S et al. Functional nature of electrogram fractionation demonstrated by left atrial high-density mapping. Circ Arrhythm Electrophysiol. 2012 Feb;5(1):32–42.
8. Marchlinski FE, Callans DJ, Gottlieb CD, Zado E. Linear Ablation Lesions for Control of Unmappable Ventricular Tachycardia in Patients With Ischemic and Nonischemic Cardiomyopathy. Circulation. 2000 Mar 21;101(11):1288–96.
9. Reddy VY, Wrobleski D, Houghtaling C, Josephson ME, Ruskin JN. Combined epicardial and endocardial electroanatomic mapping in a porcine model of healed myocardial infarction. Circulation. 2003 Jul 1;107(25):3236–42.
10. Tanaka Y, Genet M, Chuan Lee L, Martin AJ, Sievers R, Gerstenfeld EP. Utility of high-resolution electroanatomic mapping of the left ventricle using a multispline basket catheter in a swine model of chronic myocardial infarction. Heart Rhythm. Elsevier; 2015 Jan;12(1):144–54.
11. Cokic I, Kali A, Wang X, Yang H-J,et al. Iron deposition following chronic myocardial infarction as a substrate for cardiac electrical anomalies: initial findings in a canine model. PLoS One. 2013 Jan;8(9):e73193.
12. Stevenson WG, Soejima K. Catheter ablation for ventricular tachycardia. Circulation. 2007 May 29;115(21):2750–60.
13. Schneider HE, Schill M, Kriebel T, Paul T. Value of dynamic substrate mapping to identify the critical diastolic pathway in postoperative ventricular reentrant tachycardias after surgical repair of tetralogy of fallot. J Cardiovasc Electrophysiol. 2012 Sep;23(9):930–7.
14. Mantziari L, Suman-Horduna I, Gujic M et al. Use of asymmetric bidirectional catheters with different curvature radius for catheter ablation of cardiac arrhythmias. Pacing Clin Electrophysiol. 2013 Jun;36(6):757–63.
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Figure legends
Figure 1: The mini-basket catheter-The mini-basket catheter (IntellaMap Orion, Boston Scientific) has a
bidirectional deflectable shaft. The mini-basket consists of 8 splines with 8 closely spaced mini electrodes
on each and can be used in various degrees of deployment from undeployed (3mm) to fully deployed
(22mm).
Figure 2: Example of incorrect automatic annotation-(A) The electrogram corresponding to the blue
point (shown with red arrow) is automatically annotated on the far field V because this signal is larger than
the near field A. Note that blanking of the V (red column) was set to avoid this error however it was too
narrow to cover the late V electrograms that appear close to the tricuspid annulus. The area of incorrect
annotation (inside black box) on the RA map is easily recognised as a spot of inconsistent colour coding. On
the right panel the manual correction of the annotation is shown. This results to change of the color and the
shape of the point on the map that now appears as orange ring. (B) Area of incorrect annotation (inside
black box, magnified in the middle) shown as a spot of inconsistent colour coding on the left ventricular map
during ventricular tachycardia because of artefact mistaken as QRS complex (V).
Figure 3: Typical atrial flutter-RA maps in Left Anterior Oblique (LAO) caudal view (case 11): (A) Voltage
and activation map of the RA during typical counter-clock wise atrial flutter. (B) Voltage map after ablation
on the CTI line showing low voltage along the line but a possible isthmus of conduction. The activation mode
of the same map shows a gap on the CTI line and conduction of the activation during CS pacing. Review of
the points on the site of the gap shows fractionated signal. (C) Voltage map after further ablation on the gap
shows very low voltage along the line. The time map confirms bidirectional block with widely split double
potentials
Figure 4: Linear lesions-(A) Focused map of the LA roof seen from above (superior view of the roof)
during pacing from the left atrial appendage (LAA- the LAA is not shown on this map). The local electrogram
at the site of the gap is 39 ms earlier to the reference (CS 7-8). (B) Additional ablation on the site indicated
in (A) resulted in roof line block. (B) Activation and voltage maps of the LA roof are shown with double
potential on the roof line. (C) Focused map of the mitral isthmus area after a mitral isthmus line was
deployed. Activation map is shown during pacing from the LAA (case 13). A breakthough of activation is
seen in the middle of the mitral isthmus line with the corresponding fractionated local electrogram (EGM).
The voltage map below shows an isthmus of very low voltage on the mitral line. The voltage on the gap is
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0.068mV. (D) Re-map of the mitral isthmus area in LAA pacing after further ablation shows no endocardial
conduction in the mitral isthmus and scar along the line. However there is still epicardial conduction over
the CS. Further ablation inside the CS resulted in MVI block.
Figure 5: Left ventricular tachycardia-Maps are focused on the inferobasal LV wall. (A) Mapping of the
full tachycardia CL (262 ms) shows a possible isthmus of conduction but the right part of it is confusing
(dashed white arrow). Magnification of this area shows a lot of points with different colors resulting from
incorrect annotation, see explanation in B. (B) The system automatically annotates the largest signal within
the mapping window. When the mapping window includes the systolic activation and this happens to be
larger than the local diastolic electrogram, then the system automatically annotates the far field systolic
potential (yellow dashed line). We can manually correct this by dragging the annotation to the near field
signal (blue dashed line). A more efficient way to avoid this is to shorten the mapping window to exclude
the systolic and focus on the diastolic part of the VT. (C) This map is automatically generated after we
shortened the mapping window to 108ms focused on the diastole and it clearly shows a figure-of-8
ventricular tachycardia with early diastolic potentials at the entry site (1), mid-diastolic potentials in the
isthmus (2) and presystolic potentials at the exit site (3). (D) Substrate map of the inferobasal LV wall in SR.
The scar threshold cut-off is reduced to 0.2 mV to reveal isthmuses of low voltage within the scar area.
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Table 1: Case Description
Case #
age Clinical tachycardia
Cardiovascular history Previous ablations
Ablation endpoint duration/ fluoroscopy(minutes)
Number of Maps
Chamber mapped
complications
Follow duration/outcome
1 72 Typical atrial flutter, persistent
Normal heart - Bidirectional CTI conduction block
135/ 10.0 2 RA none 6 months/no recurrence
2 84 Paroxysmal AT Normal heart - Left ATEPS only*
111/9.0 3 RA none No ablation
3 85 Persistent AT Normal heart - Left ATEPS only*
55/4.1 1 RA none No ablation
4 48 Typical atrial flutter, paroxysmal
Normal heart - Bidirectional CTI conduction block
80/14.5 2 RA none 6 months/no recurrence
5 68 Paroxysmal AF Normal heart - PVI 177/24.1 2 LA none 5 months/No recurrence
6 39 Persistent AT ACHD(AVSD and cleft MV repair)
+Right
ATs/AF
3 right ATs were induced and ablated.
178/14.1 6 RA none 4 months/12 min of SVT
7 80 Persistent AF Normal heart - PVI, roof, MVI, endocardial CS, anterior wall CFAE ablation, endocardial CS, CTI
168/39.0 3 RALA
none 6 months/ no recurrence
8 54 VEs (LV) ACHD (Dextrocardia, ASD surgically repaired)
- Transient elimination of VEs with endocardial ablation
188/26.0 2 LV none 3 months/ NSVT
9 62 Long standing persistent AF
DCM EF 30% - PVI, roof, MVI, endocardial CS, CTI
210/10.6 2 RALA
none 5 months/ no recurrence
10 46 Persistent AF DCMEF 29%
- PVI, roof, MVI, endocardial CS lineAF organised to perimitral AT that changed to CTI dependent flutter. Termination to SR from CTI ablationGap on MVI ablated until block
320/21.6 5 RALA
none 3 months/no recurrence
11 54 Persistent atrial flutter
ACHD (VSD, Eisenmenger syndrome)
- Bidirectional CTI conduction block
69/10.4 4 RA none 4 months/no recurrence
12 75 Persistent AF Ischemic heart diseaseEF 60%
- PVI, roof, MVI, posterior line, CTIDCCV to roof dependent macro-reentrant ATAblation to SR
212/8.9 4 RALA
none 3 months/no recurrence
13 71 Persistent AF Normal heart - PVI, roof, MVI, CTI 177/23.7 5 RALA
none 5 months/ no recurrence
14 84 Paroxysmal AT DCMEF 55%
+persistent
AF
Perimitral re-entry ATMVI block
300/14.0 3 LA none 4 months/ no
16
recurrence
15 80 Persistent AF ICM- EF 40% + Typical flutter
PVI, roof, MVI, endocardial CSDCCV to SRGap on MVI- ablation until blockCTI blocked from previous procedure
276/51.0 3 RALA
none 2 months/persistent atrial flutter
16 71 VT storm ICM- EF 20% - Ablated 2 VTs in LV.No other VT inducible
265/34.4 2 LV none 4 months/ recurrence of VT as inpatient
17 54 VT and AT ACHD (Bicuspid aortic valve, Ross procedure, MI post surgery, right coronary artery to right atrial fistula)
- Ablated 2 VTs in LV.Ablated dual-loop re-entry AT (CTI and atriotomy dependent)Non inducibility of any tachycardia
298/30.7 8 LVRA
Small pseudoaneurysm of right superficial femoral artery
4 months/ no recurrence
18 85 VT storm ICM EF 27% - Poorly tolerated VT. Substrate mapping and ablation of late potentials. Clinical VT not inducible
302/61.0 1 LV none 2 months/ no recurernce
19 85 VEs ICM EF 30% - LVOT VEsElimination of VEs
134/22.1 1 LV none 3 months/ no recurrence
20 74 Persistent AF ICMEF 55%
- PVI, roof, MVI, posterior line, Left septum CFAE ablation, CTIAT- perimitral re-entry ablation to SR
330/62.0 3 RALA
none 2 months/ one episode of AF in blanking period
* Not consented for left sided procedure
CTI, Cavotricuspid isthmus;RA, right atrium;AT, atrial tachycardia;EPS, electrophysiological study;AF, atrial
fibrillation;PVI, pulmonary vein isolation;LA, left atrium;ACHD, adult congenital heart disease;AVSD,
atrioventricular septal defect;MV, mitral valve;MVI, mitral valve isthmus;CS, coronary sinus;CFAE, complex
fractionated atrial electrograms;VEs, ventricular ectopics;LV, left ventricle;ASD, atrial septal
defect;DCM,dilated cardiomyopathy;EF, ejection fraction;VSD, ventricular septal defect;DCCV, direct current
cardioversion;ICM,ischemic cardiomyopathy;VT, ventricular tachycardia;MI, myocardial infarction;LVOT,
left ventricular outflow tract
17
Table 2: Summary of maps
Right atrial maps
N=30
Left atrial maps
N=22
Left ventricular
maps n=10
P values
(LA to RA; LV
to RA)
Time, min 10.5 (4.1-15) 10.8 (5.8-19.3) 36.6 (13.6-43.2) 0.98; <0.0001
Accepted beats 540 (293-932) 758 (173-1175) 1123 (288-1732) 0.74; 0.36
Electrograms 7220 (3467-10947) 7818 (4379-12262) 8709 (2605-15514) 0.79; 0.81
18