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1.  Catheter Ablation of Idiopathic Premature Ventricular Contractions and Ventricular Tachycardias Originating from Right Ventricular Septum 
PLoS ONE  2013;8(6):e67038.
Background
Idiopathic premature ventricular contractions (PVCs) and ventricular tachycardias (IVTs) originating from the subtricuspid septum and near the His bundle have been reported. However, little is known about the prevalence, distribution, electrocardiographic characteristics and the efficacy of radiofrequency catheter ablation (RFCA) for the ventricular arrhythmias arising from the right ventricular (RV) septum. This study aimed to investigate electrocardiographic characteristics and effects of RFCA for patients with symptomatic PVCs/IVTs, originating from the different portions of the RV septum.
Methodology/Principal Findings
Characteristics of body surface electrocardiogram and electrophysiologic recordings were analyzed in 29 patients with symptomatic PVCs/IVTs originating from the RV septum. Among 581 patients with PVCs/IVTs, the incidence of ventricular arrhythmias originating from the RV septum was 5%. Twenty (69%) had PVCs/IVTs from the septal portion of the tricuspid valvular RV region (3 from superoseptum, 15 from midseptum, 2 from inferoseptum), and 9 (31%) from the septal portion of the basal RV (1 from superoseptum, 4 from midseptum, 4 from inferoseptum). There were different characteristics of ECG of PVCs/VT originating from the different portions of the RV septum. Twenty-seven of 29 patients with PVCs/IVTs arising from the RV septum were successfully ablated (93.1% acute success).
Conclusions/Significance
ECG characteristics of PVCs/VTs originating from the different portions of the RV septum are different, and can help regionalize the origin of these arrhythmias. The septal portion of the tricuspid valvular RV region was the preferential site of origin. RFCA was effective and safe for the PVCs/IVTs arising from the RV septum.
doi:10.1371/journal.pone.0067038
PMCID: PMC3692551  PMID: 23825610
2.  Catheter Ablation of Idiopathic Premature Ventricular Contractions and Ventricular Tachycardias Originating from the Vicinity of Endocardial and Epicardial Mitral Annulus 
PLoS ONE  2013;8(11):e80777.
Background
Several previous reports have revealed that idiopathic ventricular arrhythmias (VAs), including premature ventricular contractions (PVCs) and ventricular tachycardias (IVTs), can originate from endocardial mitral annulus (ENDO MA). However, these data are limited to ENDO MA VAs, and little is known about the electrocardiographic (ECG) characteristics and the efficacy of radiofrequency catheter ablation (RFCA) via the coronary venous system for the VAs arising from the epicardial MA (EPI MA).
Methodology/Principal Findings
Characteristics of body surface electrocardiogram and electrophysiologic recordings were analyzed in 21 patients with symptomatic PVCs/IVTs originating from the vicinity of MA. Among 597 patients with PVCs/IVTs, the incidence of VAs originating from the ENDO and EPI MA was 3.52% (21 cases). Eleven (52%) from the ENDO MA, and 10 (48%) from the EPI MA. There were different characteristics of ECG of PVCs/VT originating from the ENDO and EPI MA. The prolonged pseudodelta wave time and intrinsicoid deflection time in lead V2 and the precordial maximum deflection index reliably differentiated EPI MA VAs from ENDO MA VAs with high sensitivity and specificity. Successful RFCA in 18 patients could be achieved (85.7% acute procedural success).
Conclusions/Significance
ECG characteristics of PVCs/VTs originating from the different portions of the MA are different, and can help regionalize the origin of these arrhythmias. RFCA within the coronary venous system was relatively effective and safe for the PVCs/IVTs and should be seen as an alternative approach, when the MA PVCs/IVTs could not be eliminated by RFCA from the endocardium.
doi:10.1371/journal.pone.0080777
PMCID: PMC3842333  PMID: 24312241
3.  Premature ventricular contractions originating from the left ventricular septum: Results of Radiofrequency Catheter Ablation in twenty patients 
Background
RFCA has been established as an effective and curative therapy for severely symptomatic PVC from the outflow tract in structurally normal hearts. However, it is unknown whether PVCs originating from the left ventricular septum, are effectively eliminated by RFCA. This study aimed to investigate electrophysiologic characteristics and effects of Radiofrequency catheter ablation (RFCA) for patients with symptomatic premature ventricular contraction (PVC) originating from the left ventricular septum without including fascicular PVCs.
Methods
Characteristics of body surface electrocardiogram (ECG) and electrophysiologic recordings endocardiogram in a successful RFCA target were analyzed in 20 patients with symptomatic PVCs originating from the left ventricular septum. RFCA was performed using pace mapping and activation mapping.
Results
The QRS morphology of PVCs originating from the left ventricular septum is similar to that seen in fascicular tachycardia. Most of the PVCs originated from the left septum appears in the form of ventricular parasystole. The incidence of ventricular parasystole was 70%. Sustained ventricular tachycardia was not inducible by electrical stimulation and isoproterenol infusion in all 20 patients, ablation at the site recording the earliest Purkinje potential was not effective in all 20 patients, and Purkinje potentials were not identified at successful sites during point mapping. Sixteen patients were successful with RFCA using pace mapping and activation mapping, 3 failed, and 1 recurrent.
Conclusion
Although the ECG characteristics of the PVCs arising from the left ventricular septum are similar to that seen in fascicular tachycardia, the electrophysiologic characteristics are different between the two types of PVCs. The distinguishing characteristic of the PVCs is that Purkinje potentials were not present at the site of successful ablation, suggesting a myocardial as opposed to fascicular substrate. RFCA is an effective curative therapy for symptomatic PVCs originating from the left ventricular septum (not from the left anterior and posterior fascicle).
doi:10.1186/1471-2261-11-27
PMCID: PMC3123650  PMID: 21635765
4.  Electrocardiogram features of premature ventricular contractions/ventricular tachycardia originating from the left ventricular outflow tract and the treatment outcome of radiofrequency catheter ablation 
Background
Radiofrequency catheter ablation (RFCA) has been used for the ablation of premature ventricular contractions (PVCs) or ventricular tachycardia (VT). To date, the mapping and catheter ablation of the arrhythmias originating from the left ventricular outflow tract (LVOT) has not been specified. This study investigates the electrocardiogram (ECG) feature of PVCs or VT originating from the LVOT. Moreover, the treatment outcome of RFCA is analyzed.
Methods
Mapping and ablation were performed on the supravalvular or subvalvular aorta in 52 cases with PVCs/VT originating from the LVOT. The data were compared with those from 104 patients with PVCs/VT originating from the right ventricular outflow tract (RVOT). A differential procedure was prepared based on the comparison of the ECG features of PVCs/VT originating from the RVOT, LVOT, and their different parts.
Results
Among 52 cases with PVCs originating from the LVOT, 47 were successfully treated by RFCA, with a success rate of 90.38%. Several differences among the 12-lead ECG features were observed from the RVOT and LVOT in the left and right coronary sinus groups, as well as under the left coronary sinus group (left fibrous trigone): (1) If the precordial leads transition 0 are considered as the diagnostic parameters of PVCs/VT originating from the LVOT, then the sensitivity, specificity, as well as positive and negative predictive values are 94.12%, 93.00%, 87.27%, and 96.88%, respectively; (2) The analysis of different subgroups of the LVOT are as follows: (a) A mainly positive wave of r or m pattern was recorded in the lead I in 72.73% of patients in the right coronary sinus group, versus 12.90% of patients in the left coronary sinus group, and 0% in the under left coronary sinus group. (b) All patients in the right coronary sinus group presented waves of RII>RIII and QSaVR>QSaVL, whereas most patients in the other two groups showed waves of RIII>RII and QSaVL>QSaVR. (c) Most patients in the under left coronary sinus group in lead V1 had a mainly positive wave (R) (77.78%), whereas those in the right (81.82%) and left (62.50%) coronary sinus groups had mainly negative waves (rS).
Conclusions
RFCA is a safe and effective curative therapy for PVCs/VT originating from the LVOT. The 12-lead ECG features of the LVOT from different origins exhibit certain distinctions.
doi:10.1186/1471-2261-12-112
PMCID: PMC3571934  PMID: 23186541
Electrophysiology; Ventricular arrhythmia; Left ventricular outflow; Catheter ablation; Radiofrequency current
5.  Noninvasive electrocardiographic mapping to guide ablation of outflow tract ventricular arrhythmias 
Heart Rhythm  2014;11(4):587-594.
Background
Localizing the origin of outflow tract ventricular tachycardias (OTVT) is hindered by lack of accuracy of electrocardiographic (ECG) algorithms and infrequent spontaneous premature ventricular complexes (PVCs) during electrophysiological studies.
Objectives
To prospectively assess the performance of noninvasive electrocardiographic mapping (ECM) in the pre-/periprocedural localization of OTVT origin to guide ablation and to compare the accuracy of ECM with that of published ECG algorithms.
Methods
Patients with symptomatic OTVT/PVCs undergoing clinically indicated ablation were recruited. The OTVT/PVC origin was mapped preprocedurally by using ECM, and 3 published ECG algorithms were applied to the 12-lead ECG by 3 blinded electrophysiologists. Ablation was guided by using ECM. The OTVT/PVC origin was defined as the site where ablation caused arrhythmia suppression. Acute success was defined as abolition of ectopy after ablation. Medium-term success was defined as the abolition of symptoms and reduction of PVC to less than 1000 per day documented on Holter monitoring within 6 months.
Results
In 24 patients (mean age 50 ± 18 years) recruited ECM successfully identified OTVT/PVC origin in 23/24 (96%) (right ventricular outflow tract, 18; left ventricular outflow tract, 6), sublocalizing correctly in 100% of this cohort. Acute ablation success was achieved in 100% of the cases with medium-term success in 22 of 24 patients. PVC burden reduced from 21,837 ± 23,241 to 1143 ± 4039 (P < .0001). ECG algorithms identified the correct chamber of origin in 50%–88% of the patients and sublocalized within the right ventricular outflow tract (septum vs free-wall) in 37%–58%.
Conclusions
ECM can accurately identify OTVT/PVC origin in the left and the right ventricle pre- and periprocedurally to guide catheter ablation with an accuracy superior to that of published ECG algorithms.
doi:10.1016/j.hrthm.2014.01.013
PMCID: PMC4067940  PMID: 24440381
CT, computed tomographic; EF, ejection fraction; ECG, electrocardiographic; ECM, electrocardiographic mapping; EPS, electrophysiological study; LV, left ventricular/ventricle; LVOT, left ventricular outflow tract; OTVT, outflow tract ventricular tachycardia; PVC, premature ventricular complex; PVS, programmed ventricular stimulation; RV, right ventricular/ventricle; RVOT, right ventricular outflow tract; VT, ventricular tachycardia; Ventricular tachycardia; Premature ventricular complex; Outflow tract tachycardia
6.  Idiopathic Epicardial Ventricular Arrhythmias: Diagnosis and Ablation Technique from the Aortic Sinus of Valsalva 
Idiopathic outflow tract arrhythmias (ventricular tachycardias or symptomatic premature ventricular contractions; OT-VT/PVCs) can originate from the left ventricular (LV) epicardium (Epi-VT/PVCs), and radiofrequency (RF) energy applications from the aortic sinus of Valsalva can eliminate Epi-VT/PVCs in selected patients. Among the various ECG findings, the R-wave duration index and R/S amplitude index in leads V1 or V2 are useful for identifying Epi-VT/PVCs, and the Q-wave ratio of leads aVL to aVR and S-wave amplitude in lead V1 are useful for differentiating between an Epi-VT/PVC originating from the LV epicardium remote from the left sinus of Valsalva (LSV) and that from the LSV. Tissue tracking imaging is a promising modality for identifying the origin of OT-VT/PVCs and for differentiating between an Epi-VT/PVC originating from the LV epicardium remote from the LSV and that from the LSV.
If the origin of the Epi-VT/PVC is identified within the LSV, coronary and aortic angiography should be performed to assess the anatomic relationships between the Epi-VT/PVC origin and coronary arteries and aortic valve before the RF energy delivery. To avoid potential complications, RF ablation should be performed at the LSV using a maximum power of 35 watts and maximum temperature of 55°C. Epicardial mapping through the coronary venous system and the presence of potentials recorded from the ablation site within the LSV and their changes before and after the RF energy applications may be useful for diagnosing Epi-VT/PVCs or predicting a successful catheter ablation from the LSV.
PMCID: PMC1502079  PMID: 16943950
Ventricular tachycardia; left sinus of Valsalva; potential; premature ventricular contraction; catheter ablation; tissue tracking imaging
7.  Impact of Radiofrequency Ablation of Frequent Post-Infarction Premature Ventricular Complexes on Left Ventricular Ejection Fraction 
Background
Frequent idiopathic premature ventricular complexes (PVC) are associated with a reversible form of cardiomyopathy. The effect of frequent PVCs on left ventricular function has not been evaluated in post-infarction patients.
Objective
To evaluate the value of post-infarction PVC ablation and possible determinants of a reversible cardiomyopathy.
Methods
Thirty consecutive patients (24 men, age 61±12, LVEF 0.36±0.12) with remote myocardial infarction referred for ICD implantation for primary prevention of sudden death or for management of symptomatic ventricular tachycardia or PVCs were evaluated. Fifteen patients with a high PVC burden (≥5% of all QRS complexes on 24-hour Holter) underwent mapping and ablation of PVCs before ICD implantation. The remaining 15 patients served as a control group. LVEF was assessed by echocardiography, and scar burden was assessed by cardiac MRI with delayed enhancement (DE-MRI) in both groups.
Results
PVC ablation was successful in 15/15 patients and reduced the mean PVC burden from 22±12% to 2.6±5.0% (p<0.001). Following the procedure, LVEF increased significantly from 0.38±0.10 to 0.51±0.09 in the PVC ablation group (p=0.0001). In the control group, LVEF remained unchanged within the same time frame (0.34±0.14 vs. 0.33±0.15; p=0.6). Patients with frequent PVCs had a significantly smaller scar burden by DE-MRI compared to control patients. Five of the patients with frequent PVCs underwent ICD implantation.
Conclusion
Post-infarction patients with frequent PVCs may have a reversible form of cardiomyopathy. DE-MRI may identify patients in whom the LVEF may improve after ablation of frequent PVCs.
doi:10.1016/j.hrthm.2009.08.004
PMCID: PMC2792731  PMID: 19879531
catheter ablation; left ventricular ejection fraction; magnetic resonance imaging; myocardial infarction; premature ventricular complexes
8.  Cardiomyopathy Due to Nonsustained Ventricular Tachycardia Originating from the Aortic Sinus Cusp 
We report a case of idiopathic nonsustained ventricular tachycardia (VT) originating from the aortic sinus cusp referred for presyncope and LV dysfunction and frequent premature ventricular complex with no response to 3 months anti-arrhythmic medication for heart failure and arrhythmia. She was then referred to us for frequent PVC's and runs of nonsustained VT. ECG recorded during the nonsustained VT showed a left bundle branch block pattern in the precordial leads and an inferior axis and early transition in precordial leads in V3-V4. QS morphology in lead V1 was noticed with notching on the downward deflection. Electrophysiologic study was conducted to map ventricular outflow tract as a classic method, although pace map failed to find any matched QRS with the spontaneous PVCs. The mapping of aortic cusps was also performed. The best potential was recorded in a region located at the commissure of left-right aortic cusps. A single radiofrequency energy was delivered which resulted in immediate elimination of PVCs. The patient was discharged the day after ablation without any PVC recorded on monitor. Left ventricular ejection fraction(LVEF) improved to normal level two months later. There was no PVC detected at serial holter monitoring. It seems logical not to overlook even an isolated or nonsustained ventricular arrhythmia considering the available and effective treatments such as ablation rather than congestive heart failure(CHF) therapy especially in a young patient.
PMCID: PMC3987425  PMID: 24757616
Electrophysiology; Radiofrequency Ablation; PVC
9.  Coupling Interval Variability Differentiates Ventricular Ectopic Complexes Arising in the Aortic Sinus of Valsalva and Great Cardiac Vein From Other Sources 
Objectives
The objective of this study was to determine whether premature ventricular contractions (PVCs) arising from the aortic sinuses of Valsalva (SOV) and great cardiac vein (GCV) have coupling interval (CI) characteristics that differentiate them from other ectopic foci.
Background
PVCs occur at relatively fixed CI from the preceding normal QRS complex in most patients. However, we observed patients with PVCs originating in unusual areas (SOV and GCV) in whom the PVC CI was highly variable. We hypothesized that PVCs from these areas occur seemingly randomly because of the lack of electrotonic effects of the surrounding myocardium.
Methods
Seventy-three consecutive patients referred for PVC ablation were assessed. Twelve consecutive PVC CIs were recorded. The ΔCI (maximum – minimum CI) was measured.
Results
We studied 73 patients (age 50 ± 16 years, 47% male). The PVC origin was right ventricular (RV) in 29 (40%), left ventricular (LV) in 17 (23%), SOV in 21 (29%), and GCV in 6 (8%). There was a significant difference between the mean ΔCI of RV/LV PVCs compared with SOV/GCV PVCs (33 ± 15 ms vs. 116 ± 52 ms, p < 0.0001). A ΔCI of >60 ms demonstrated a sensitivity of 89%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 94%. Cardiac events were more common in the SOV/GCV group versus the RV/LV group (7 of 27 [26%] vs. 2 of 46 [4%], p < 0.02).
Conclusions
ΔCI is more pronounced in PVCs originating from the SOV or GCV. A ΔCI of 60 ms helps discriminate the origin of PVCs before diagnostic electrophysiological study and may be associated with increased frequency of cardiac events.
doi:10.1016/j.jacc.2014.02.551
PMCID: PMC4282189  PMID: 24657687
aortic sinus of Valsalva; oupling interval; great cardiac vein; premature ventricular contraction
10.  Electrophysiologic Studies and Radiofrequency Catheter Ablation of Ectopic Atrial Tachycardia in Children 
Pediatric Cardiology  2010;32(1):40-46.
Ectopic atrial tachycardia (EAT) often resists medical therapy, making radiofrequency catheter ablation (RFCA) the preferred treatment. This study reviewed the records of 35 patients who underwent electrophysiologic studies (EPS) and 39 RFCA procedures for EAT during a 10-year period. Of the 35 patients, 10 (28%) presented with decreased ventricular function and tachycardia-induced cardiomyopathy (TIC). The EAT originated on the right atrial side in 19 patients (54%) and on the left atrial side in the remaining 16 patients (46%). The right atrial sites included the right atrial appendage (RAA) (n = 9, 25%), the tricuspid annulus (n = 7, 20%), and the crista terminalis (n = 3). The left atrial sites included the left atrial appendage (LAA) (n = 6, 17%), the pulmonary veins (n = 5, 14%), the mitral annulus (n = 3), and the posterior wall of the left atrium (n = 2). The mechanism of all EAT probably is automaticity. All EATs could be abolished using RFCA. Follow-up data were available for all patients 2 to 8 years after RFCA. All 35 patients remained recurrence free, and ventricular function improved for all 10 patients with TIC. The origin of EAT in children differed from its origin in adults. The authors conclude that RFCA is a safe and effective treatment option for children with refractory EAT and should be considered early in the course of their illness.
doi:10.1007/s00246-010-9809-3
PMCID: PMC3018255  PMID: 20936469
Catheter Ablation; Children; Ectopic atrial tachycardia
11.  Radiofrequency Catheter Ablation for Unifocal Premature Ventricular Complexes Triggering Recurrent Ventricular Fibrillations in a Young Man Without Structural Heart Disease 
Korean Circulation Journal  2012;42(8):575-579.
A 17-year-old man was referred for aborted sudden cardiac death. Ventricular fibrillation (VF) was recorded by automated external defibrillator. Post-resuscitation electrocardiograms showed frequent monomorphic premature ventricular complexes (PVCs), with left bundle branch block configuration and inferior axis. Cardiac arrest due to VF recurred twice within the initial 42 hours. Rhythm monitoring revealed multiple episodes of sustained VF triggered by a triplet of monomorphic PVCs having similar morphology with isolated PVCs. Comprehensive cardiologic workup revealed no structural heart disease and ion-channelopathies. With the impression of idiopathic VF triggered by unifocal PVCs of right ventricular outflow tract (RVOT) origin, radiofrequency catheter ablation was performed to prevent frequent VF recurrence before implantable cardioverter-defibrillator (ICD) implantation. After successful ablation of the origin of unifocal PVCs at anterolateral wall of RVOT, the burden of PVCs decreased remarkably and VF did not recur. The patient was discharged after ICD implantation.
doi:10.4070/kcj.2012.42.8.575
PMCID: PMC3438271  PMID: 22977457
Ventricular fibrillation; Radiofrequency catheter ablation
12.  Electrophysiological Characteristics Related to Outcome after Catheter Ablation of Idiopathic Ventricular Arrhythmia Originating from the Papillary Muscle in the Left Ventricle 
Korean Circulation Journal  2013;43(12):811-818.
Background and Objectives
The electrophysiological properties associated with favorable outcome of radiofrequency catheter ablation (RFCA) for idiopathic ventricular arrhythmia (VA) originating from the papillary muscle (PM) remain unclear. The purpose of this study was to investigate the relationships of electrophysiological characteristics and predictors with the outcome of RFCA in patients with VAs originating from PM in the left ventricle (LV).
Subjects and Methods
Twelve (4.2%) of 284 consecutive patients with idiopathic VAs originating from LV PM were assessed. The electrophysiological data were compared between the patients in the successful group and patients in the recurrence group after RFCA.
Results
In 12 patients with PM VAs, non-sustained ventricular tachycardias (VTs, n=6), sustained VTs (n=4) and premature ventricular complexes (n=2) were identified as the presenting arrhythmias. Seven of eight patients showing high-amplitude discrete potentials at the ablation site had a successful outcome (85.7%), while the remaining four patients who showed low-amplitude fractionated potentials at the ablation site experienced VA recurrence. The mean duration from onset to peak downstroke (Δt) on the unipolar electrogram was significantly longer in the successful group than in the recurrence group (58±8 ms vs. 37±9 ms, p=0.04). A slow downstroke >50 ms of the initial Q wave on the unipolar electrogram at ablation sites was also significantly associated with successful outcome (85.7% vs. 25.0%, p=0.03).
Conclusion
In PM VAs, the high-amplitude discrete potentials before QRS and slow downstroke of the initial Q wave on the unipolar electrogram at ablation sites were related to favorable outcome after RFCA.
doi:10.4070/kcj.2013.43.12.811
PMCID: PMC3875697  PMID: 24385992
Papillary muscles; Left ventricle; Arrhythmia; Catheter ablation
13.  Localization of premature ventricular contraction foci in normal individuals based on multichannel electrocardiogram signals processing 
SpringerPlus  2013;2:486.
A premature ventricular contraction (PVC) is relatively a common event where the heartbeat is initiated by the other pathway rather than by the Sinoatrial node, the normal heartbeat initiator. Determining PVC foci is important for ablation procedure and it can help in pre-procedural planning and potentially may improve ablation outcome.
In this study, 12-lead Electrocardiogram (ECG) of 87 patients without structural cardiac diseases, who had experienced PVC, were obtained. Initially, PVC foci were labeled based on Electrophysiology study (EPS) reports. PVC beats were detected by wavelet method and their foci were classified using Mahalanobis distance and One-way ANOVA. Using morphological, frequency and spectrogram features, these foci in the heart were classified into five groups: Left Ventricular Outflow Tract (LVOT), Right Ventricular Outflow Tract (RVOT) septum, basal Right Ventricular (RV), RVOT free-wall, and Aortic Cusp (AC).
The results showed that 88.4% of patients are classified correctly.
doi:10.1186/2193-1801-2-486
PMCID: PMC3790125  PMID: 24098858
Electrocardiogram; Premature ventricular beats; PVC foci (focuses)
14.  Coexisting Sustained Tachyarrthymia in Patients With Atrial Fibrillation Undergoing Catheter Ablation 
Korean Circulation Journal  2010;40(5):235-238.
Background and Objectives
During the index procedure of catheter ablation (CA) for atrial fibrillation (AF), it is important to assess whether other atrial or ventricular tachyarrhythmia coexist. Their symptoms are often attributed to residual tachycardia after successful elimination of AF by CA. This tachycardia could also be non-pulmonary vein (PV) foci initiated AF. This study examined the coexistence of other sustained tachyarrhythmia of patients who underwent radiofrequency CA (RFCA) for AF.
Subjects and Methods
Four hundred fifty-nine consecutive patients (375 males, aged 53.4±11.4 years) who underwent RFCA for AF were investigated. Atrial and ventricular programmed stimulation (PS) with or without isoproterenol infusion were performed, and spontaneously developed tachycardias were analyzed.
Results
Fifteen patients (3.3% of total) were diagnosed to have other sustained arrhythmias that included slow-fast type atrioventricular nodal reentrant tachycardia (AVNRT, n=6), atrioventricular reentrant tachycardia (AVRT, n=5) that utilized left posteroseptal (n=4) and parahisian bypass tract (n=1), atrial tachycardia (AT, n=2) originating from the foramen ovale (n=1) and the ostium of coronary sinus (n=1), sustained ventricular tachycardia (VT, n=2) involving one from the apical posterolateral wall of left ventricule in a normal heart and one from an anterolateral wall in an underlying myocardial infarction (MI). These sustained tachycardias were neither clinically documented nor had structural heart diseases, with the exception of one patient with MI associated VT. Two patients had the triple tachycardia; one involved AVNRT, AVRT, and AF, and the other involved VT, AT, and AF. All associated tachycardias were successfully eliminated by RFCA.
Conclusion
Fifteen (3.3%) patients with AF had coexisting sustained tachycardia. RFCA was successful in these patients. Identification of tachycardia by PS before RFCA for AF should be done to maximize the efficacy of the first ablation session.
doi:10.4070/kcj.2010.40.5.235
PMCID: PMC2877788  PMID: 20514334
Atrial fibrillation; Tachycardia supraventricular; Catheter ablation
15.  Usefulness of Ventricular Endocardial Electric Reconstruction from Body Surface Potential Maps to Noninvasively Localize Ventricular Ectopic Activity in Patients 
Physics in medicine and biology  2013;58(11):3897-3909.
As radio frequency (RF) catheter ablation becomes increasingly prevalent in the management of ventricular arrhythmia in patients, an accurate and rapid determination of the arrhythmogenic site is of important clinical interest. The aim of this study was to test the hypothesis that the inversely reconstructed ventricular endocardial current density distribution from body surface potential maps (BSPMs) can localize the regions critical for maintenance of a ventricular ectopic activity. Patients with isolated and monomorphic premature ventricular contractions (PVCs) were investigated by noninvasive BSPMs and subsequent invasive catheter mapping and ablation. Equivalent current density (CD) reconstruction (CDR) during symptomatic PVCs was obtained on the endocardial ventricular surface in 6 patients (4 men, 2 women, years 23–77), and the origin of the spontaneous ectopic activity was localized at the location of the maximum CD value. Compared with the last (successful) ablation site (LAS), the mean and standard deviation of localization error of the CDR approach were 13.8 mm and 1.3 mm, respectively. In comparison, the distance between the LASs and the estimated locations of an equivalent single moving dipole (SMD) in the heart was 25.5 ± 5.5 mm. The obtained CD distribution of activated sources extending from the catheter ablation site also showed a high consistency with the invasively recorded electroanatomical maps. The noninvasively reconstructed endocardial CD distribution is suitable to predict a region of interest containing or close to arrhythmia source, which may have the potential to guide RF catheter ablation.
doi:10.1088/0031-9155/58/11/3897
PMCID: PMC3776132  PMID: 23681281
electrocardiographic inverse problem; current density reconstruction; radio frequency catheter ablation; premature ventricular contraction; body surface potential mapping
16.  Delayed-Enhanced Magnetic Resonance Imaging in Non-Ischemic Cardiomyopathy 
Objective
The purpose of this study was to assess the value of delayed-enhanced magnetic resonance imaging (DE-MRI) to guide ablation of ventricular arrhythmias in patients with non-ischemic cardiomyopathy (NIC).
Background
In patients with NIC, ventricular arrhythmias often are associated with scar tissue. DE-MRI can be used to precisely define scar tissue.
Methods
DE-MRI was performed in 29 consecutive patients (mean age 50±15 years) with NIC (mean ejection fraction 37±9%) referred for catheter ablation of ventricular tachycardia (VT) or premature ventricular complexes (PVCs). Scar was extracted from DE-MRIs and was then integrated into the electroanatomic map. Mapping data were correlated with respect to the localization of scar tissue.
Results
Scar was identified by DE-MRI in 14/29 patients. Nine of these patients had VT and five had PVCs. In 5 of the patients there was predominantly endocardial scar, and mapping and ablation of arrhythmias was effectively performed from the endocardium in all 5 patients. In 2 patients scar was either intramural or epicardial with extension to the endocardium. In both patients with partial endocardial scar extension, the ablation was effective in eliminating some but not all arrhythmias. In 2 patients most of the scar tissue was confined to the epicardium; mapping identified and eliminated an epicardial origin in both patients. No effect on arrhythmias could be achieved in the other 5 patients with predominantly intramural scar.
Conclusions
DE-MRI in patients without prior infarctions can help to identify the arrhythmogenic substrate; furthermore it helps to plan an appropriate mapping and ablation strategy.
doi:10.1016/j.jacc.2008.11.052
PMCID: PMC2747602  PMID: 19324259
non-ischemic cardiomyopathy; mapping; ablation; ventricular tachycardia; magnetic reronance imaging
17.  Determinants of Post-Infarction Ventricular Tachycardia 
Background
Structural factors contributing to the development of post-infarction ventricular tachycardia (VT) are unclear. The purpose of this study was to analyze infarct architecture and electrogram characteristics in patients with and without inducible VT and to identify correlates of post-infarction VT.
Methods and Results
Twenty-four post-infarction patients (median age 64 [53,70] years) were referred for radiofrequency catheter ablation of VT (n=12) or frequent symptomatic premature ventricular contractions (PVCs, n=12). Delayed-enhanced magnetic resonance imaging (DE-MRI) was obtained prior to ablation. Electroanatomical mapping was performed and scar area and electrogram characteristics of the scar tissue were compared in patients with and without inducible VT.
The median ejection fraction in subjects with and without inducible VT was 27% [22,43] and 43% [40,47], respectively (p=0.085). Subendocardial infarct area determined by DE-MRI was larger in patients with inducible VT (43 [38,62] cm2) than those who were non-inducible (8 [4,11] cm2, p=0.002), and unipolar and bipolar voltages on electroanatomical maps were significantly lower in inducible patients (both p<0.05). An infarct volume of >14% identified 11 of 12 patients with inducible VT (AUC 0.94, p=0.007). On electroanatomical mapping, distinct sites with isolated potentials (IPs) were more prevalent in inducible than noninducible patients (13.2% vs. 1.1% of points within scar; p<0.001). The number of inducible VTs correlated with the number of distinct sites with IPs (R=0.87, p<0.0001).
Conclusions
Scar tissue in post-infarction patients with inducible VT shows quantitative and qualitative differences from scars in patients without inducible VT. Scar size and IPs are correlated with VT inducibility.
doi:10.1161/CIRCEP.110.945295
PMCID: PMC3091263  PMID: 20937722
mocardial infarction; ventricular tachycardia; isolated potentials; scar; magnetic resonance imaging
18.  Advanced Electrophysiologic Mapping Systems 
Executive Summary
Objective
To assess the effectiveness, cost-effectiveness, and demand in Ontario for catheter ablation of complex arrhythmias guided by advanced nonfluoroscopy mapping systems. Particular attention was paid to ablation for atrial fibrillation (AF).
Clinical Need
Tachycardia
Tachycardia refers to a diverse group of arrhythmias characterized by heart rates that are greater than 100 beats per minute. It results from abnormal firing of electrical impulses from heart tissues or abnormal electrical pathways in the heart because of scars. Tachycardia may be asymptomatic, or it may adversely affect quality of life owing to symptoms such as palpitations, headaches, shortness of breath, weakness, dizziness, and syncope. Atrial fibrillation, the most common sustained arrhythmia, affects about 99,000 people in Ontario. It is associated with higher morbidity and mortality because of increased risk of stroke, embolism, and congestive heart failure. In atrial fibrillation, most of the abnormal arrhythmogenic foci are located inside the pulmonary veins, although the atrium may also be responsible for triggering or perpetuating atrial fibrillation. Ventricular tachycardia, often found in patients with ischemic heart disease and a history of myocardial infarction, is often life-threatening; it accounts for about 50% of sudden deaths.
Treatment of Tachycardia
The first line of treatment for tachycardia is antiarrhythmic drugs; for atrial fibrillation, anticoagulation drugs are also used to prevent stroke. For patients refractory to or unable to tolerate antiarrhythmic drugs, ablation of the arrhythmogenic heart tissues is the only option. Surgical ablation such as the Cox-Maze procedure is more invasive. Catheter ablation, involving the delivery of energy (most commonly radiofrequency) via a percutaneous catheter system guided by X-ray fluoroscopy, has been used in place of surgical ablation for many patients. However, this conventional approach in catheter ablation has not been found to be effective for the treatment of complex arrhythmias such as chronic atrial fibrillation or ventricular tachycardia. Advanced nonfluoroscopic mapping systems have been developed for guiding the ablation of these complex arrhythmias.
The Technology
Four nonfluoroscopic advanced mapping systems have been licensed by Health Canada:
CARTO EP mapping System (manufactured by Biosense Webster, CA) uses weak magnetic fields and a special mapping/ablation catheter with a magnetic sensor to locate the catheter and reconstruct a 3-dimensional geometry of the heart superimposed with colour-coded electric potential maps to guide ablation.
EnSite System (manufactured by Endocardial Solutions Inc., MN) includes a multi-electrode non-contact catheter that conducts simultaneous mapping. A processing unit uses the electrical data to computes more than 3,000 isopotential electrograms that are displayed on a reconstructed 3-dimensional geometry of the heart chamber. The navigational system, EnSite NavX, can be used separately with most mapping catheters.
The LocaLisa Intracardiac System (manufactured by Medtronics Inc, MN) is a navigational system that uses an electrical field to locate the mapping catheter. It reconstructs the location of the electrodes on the mapping catheter in 3-dimensional virtual space, thereby enabling an ablation catheter to be directed to the electrode that identifies abnormal electric potential.
Polar Constellation Advanced Mapping Catheter System (manufactured by Boston Scientific, MA) is a multielectrode basket catheter with 64 electrodes on 8 splines. Once deployed, each electrode is automatically traced. The information enables a 3-dimensional model of the basket catheter to be computed. Colour-coded activation maps are reconstructed online and displayed on a monitor. By using this catheter, a precise electrical map of the atrium can be obtained in several heartbeats.
Review Strategy
A systematic search of Cochrane, MEDLINE and EMBASE was conducted to identify studies that compared ablation guided by any of the advanced systems to fluoroscopy-guided ablation of tachycardia. English-language studies with sample sizes greater than or equal to 20 that were published between 2000 and 2005 were included. Observational studies on safety of advanced mapping systems and fluoroscopy were also included. Outcomes of interest were acute success, defined as termination of arrhythmia immediately following ablation; long-term success, defined as being arrhythmia free at follow-up; total procedure time; fluoroscopy time; radiation dose; number of radiofrequency pulses; complications; cost; and the cost-effectiveness ratio.
Quality of the individual studies was assessed using established criteria. Quality of the overall evidence was determined by applying the GRADE evaluation system. (3) Qualitative synthesis of the data was performed. Quantitative analysis using Revman 4.2 was performed when appropriate.
Quality of the Studies
Thirty-four studies met the inclusion criteria. These comprised 18 studies on CARTO (4 randomized controlled trials [RCTs] and 14 non-RCTs), 3 RCTs on EnSite NavX, 4 studies on LocaLisa Navigational System (1 RCT and 3 non-RCTs), 2 studies on EnSite and CARTO, 1 on Polar Constellation basket catheter, and 7 studies on radiation safety.
The quality of the studies ranged from moderate to low. Most of the studies had small sample sizes with selection bias, and there was no blinding of patients or care providers in any of the studies. Duration of follow-up ranged from 6 weeks to 29 months, with most having at least 6 months of follow-up. There was heterogeneity with respect to the approach to ablation, definition of success, and drug management before and after the ablation procedure.
Summary of Findings
Evidence is based on a small number of small RCTS and non-RCTS with methodological flaws.
Advanced nonfluoroscopy mapping/navigation systems provided real time 3-dimensional images with integration of anatomic and electrical potential information that enable better visualization of areas of interest for ablation
Advanced nonfluoroscopy mapping/navigation systems appear to be safe; they consistently shortened the fluoroscopy duration and radiation exposure.
Evidence suggests that nonfluoroscopy mapping and navigation systems may be used as adjuncts to rather than replacements for fluoroscopy in guiding the ablation of complex arrhythmias.
Most studies showed a nonsignificant trend toward lower overall failure rate for advanced mapping-guided ablation compared with fluoroscopy-guided mapping.
Pooled analyses of small RCTs and non-RCTs that compared fluoroscopy- with nonfluoroscopy-guided ablation of atrial fibrillation and atrial flutter showed that advanced nonfluoroscopy mapping and navigational systems:
Yielded acute success rates of 69% to 100%, not significantly different from fluoroscopy ablation.
Had overall failure rates at 3 months to 19 months of 1% to 40% (median 25%).
Resulted in a 10% relative reduction in overall failure rate for advanced mapping guided-ablation compared to fluoroscopy guided ablation for the treatment of atrial fibrillation.
Yielded added benefit over fluoroscopy in guiding the ablation of complex arrhythmia. The advanced systems were shown to reduce the arrhythmia burden and the need for antiarrhythmic drugs in patients with complex arrhythmia who had failed fluoroscopy-guided ablation
Based on predominantly observational studies, circumferential PV ablation guided by a nonfluoroscopy system was shown to do the following:
Result in freedom from atrial fibrillation (with or without antiarrhythmic drug) in 75% to 95% of patients (median 79%). This effect was maintained up to 28 months.
Result in freedom from atrial fibrillation without antiarrhythmic drugs in 47% to 95% of patients (median 63%).
Improve patient survival at 28 months after the procedure as compared with drug therapy.
Require special skills; patient outcomes are operator dependent, and there is a significant learning curve effect.
Complication rates of pulmonary vein ablation guided by an advanced mapping/navigation system ranged from 0% to 10% with a median of 6% during a follow-up period of 6 months to 29 months.
The complication rate of the study with the longest follow-up was 8%.
The most common complications of advanced catheter-guided ablation were stroke, transient ischemic attack, cardiac tamponade, myocardial infarction, atrial flutter, congestive heart failure, and pulmonary vein stenosis. A small number of cases with fatal atrial-esophageal fistula had been reported and were attributed to the high radiofrequency energy used rather than to the advanced mapping systems.
Economic Analysis
An Ontario-based economic analysis suggests that the cumulative incremental upfront costs of catheter ablation of atrial fibrillation guided by advanced nonfluoroscopy mapping could be recouped in 4.7 years through cost avoidance arising from less need for antiarrhythmic drugs and fewer hospitalization for stroke and heart failure.
Expert Opinion
Expert consultants to the Medical Advisory Secretariat noted the following:
Nonfluoroscopy mapping is not necessary for simple ablation procedures (e.g., typical flutter). However, it is essential in the ablation of complex arrhythmias including these:
Symptomatic, drug-refractory atrial fibrillation
Arrhythmias in people who have had surgery for congenital heart disease (e.g., macro re-entrant tachycardia in people who have had surgery for congenital heart disease).
Ventricular tachycardia due to myocardial infarction
Atypical atrial flutter
Advanced mapping systems represent an enabling technology in the ablation of complex arrhythmias. The ablation of these complex cases would not have been feasible or advisable with fluoroscopy-guided ablation and, therefore, comparative studies would not be feasible or ethical in such cases.
Many of the studies included patients with relatively simple arrhythmias (e.g., typical atrial flutter and atrial ventricular nodal re-entrant tachycardia), for which the success rates using the fluoroscopy approach were extremely high and unlikely to be improved upon using nonfluoroscopic mapping.
By age 50, almost 100% of people who have had surgery for congenital heart disease will develop arrhythmia.
Some centres are under greater pressure because of expertise in complex ablation procedures for subsets of patients.
The use of advanced mapping systems requires the support of additional electrophysiologic laboratory time and nursing time.
Conclusions
For patients suffering from symptomatic, drug-refractory atrial fibrillation and are otherwise healthy, catheter ablation offers a treatment option that is less invasive than is open surgical ablation.
Small RCTs that may have been limited by type 2 errors showed significant reductions in fluoroscopy exposure in nonfluoroscopy-guided ablation and a trend toward lower overall failure rate that did not reach statistical significance.
Pooled analysis suggests that advanced mapping systems may reduce the overall failure rate in the ablation of atrial fibrillation.
Observational studies suggest that ablation guided by complex mapping/navigation systems is a promising treatment for complex arrhythmias such as highly symptomatic, drug-refractory atrial fibrillation for which rate control is not an option
In people with atrial fibrillation, ablation guided by advanced nonfluoroscopy mapping resulted in arrhythmia free rates of 80% or higher, reduced mortality, and better quality of life at experienced centres.
Although generally safe, serious complications such as stroke, atrial-esophageal, and pulmonary vein stenosis had been reported following ablation procedures.
Experts advised that advanced mapping systems are also required for catheter ablation of:
Hemodynamically unstable ventricular tachycardia from ischemic heart disease
Macro re-entrant atrial tachycardia after surgical correction of congenital heart disease
Atypical atrial flutter
Catheter ablation of atrial fibrillation is still evolving, and it appears that different ablative techniques may be appropriate depending on the characteristics of the patient and the atrial fibrillation.
Data from centres that perform electrophysiological mapping suggest that patients with drug-refractory atrial fibrillation may be the largest group with unmet need for advanced mapping-guided catheter ablation in Ontario.
Nonfluoroscopy mapping-guided pulmonary vein ablation for the treatment of atrial fibrillation has a significant learning effect; therefore, it is advisable for the province to establish centres of excellence to ensure a critical volume, to gain efficiency and to minimize the need for antiarrhythmic drugs after ablation and the need for future repeat ablation procedures.
PMCID: PMC3379531  PMID: 23074499
19.  Usefulness of remote magnetic navigation for ablation of ventricular arrhythmias originating from outflow regions 
Netherlands Heart Journal  2009;17(6):245-249.
Monomorphic ventricular tachycardia (VT) and symptomatic monomorphic PVCs originating from the region of the right and left outflow tracts are increasingly treated by radiofrequency (RF) catheter ablation. Technical difficulties in catheter manipulation to access these outflow tract areas, very accurate mapping and reliable catheter stability are key issues for a successful treatment in this vulnerable region. VT ablation from the aortic sinus cusp (ASC) in particular carries a significant risk of perforation, of creating left coronary artery injury and of damage to the aorta and the aortic valve.
This case series describes RF ablation of VT originating in the outflow region using the remote magnetic navigation system (MNS). Potential advantages of the MNS are catheter flexibility, steering accuracy and reproducibility to navigate to a desired location with a low probability of perforating the myocardium. This report supports the idea of using advanced MNS technology during RF ablation in regions which are difficult to reach and thin walled, such as parts of the outflow tract and the ASC. (Neth Heart J 2009;17:245-9.)
PMCID: PMC2711250  PMID: 19789687
magnetic navigation; ventricular arrhythmias; outflow region
20.  Catheter Ablation of Parahisian Premature Ventricular Complex 
Korean Circulation Journal  2011;41(12):766-769.
Catheter ablation is performed in selected patients with a symptomatic premature ventricular complex (PVC) or PVC-induced cardiomyopathy. Ablation of PVC from the His region has a high risk of inducing a complete atrioventricular block. Here we report successful catheter ablation of a parahisian PVC in a 63-year-old man.
doi:10.4070/kcj.2011.41.12.766
PMCID: PMC3257464  PMID: 22259611
Premature ventricular complexes; Bundle of His; Catheter ablation
21.  Sodium Current Reduction Unmasks a Structure-Dependent Substrate for Arrhythmogenesis in the Normal Ventricles 
PLoS ONE  2014;9(1):e86947.
Background
Organ-scale arrhythmogenic consequences of source-sink mismatch caused by impaired excitability remain unknown, hindering the understanding of pathophysiology in disease states like Brugada syndrome and ischemia.
Objective
We sought to determine whether sodium current (INa) reduction in the structurally normal heart unmasks a regionally heterogeneous substrate for the induction of sustained arrhythmia by premature ventricular contractions (PVCs).
Methods
We conducted simulations in rabbit ventricular computer models with 930 unique combinations of PVC location (10 sites) and coupling interval (250–400 ms), INa reduction (30 or 40% of normal levels), and post-PVC sinus rhythm (arrested or persistent). Geometric characteristics and source-sink mismatch were quantitatively analyzed by calculating ventricular wall thickness and a newly formulated 3D safety factor (SF), respectively.
Results
Reducing INa to 30% of its normal level created a substrate for sustained arrhythmia induction by establishing large regions of critical source-sink mismatch (SF<1) for ectopic wavefronts propagating from thin to thick tissue. In the same simulations but with 40% of normal INa, PVCs did not induce reentry because the volume of tissue with SF<1 was >95% smaller. Likewise, when post-PVC sinus activations were persistent instead of arrested, no ectopic excitations initiated sustained reentry because sinus activation breakthroughs engulfed the excitable gap.
Conclusion
Our new SF formulation can quantify ectopic wavefront propagation robustness in geometrically complex 3D tissue with impaired excitability. This novel methodology was applied to show that INa reduction precipitates source-sink mismatch, creating a potent substrate for sustained arrhythmia induction by PVCs originating near regions of ventricular wall expansion, such as the RV outflow tract.
doi:10.1371/journal.pone.0086947
PMCID: PMC3904970  PMID: 24489810
22.  Premature ventricular complexes & risk of incident stroke: The Atherosclerosis Risk In Communities (ARIC) study 
Background
Ventricular premature complexes (PVCs) on a 2-minute electrocardiogram (ECG) are a common, largely asymptomatic finding, associated with increased risk of coronary heart disease (CHD) and death. They may reflect atherosclerosis or other pathogenic pathways that predispose to arrhythmias and stroke.
Methods/Results
We conducted a prospective evaluation of the Atherosclerosis Risk In Communities Study cohort (n=14,783) of middle aged men and women to assess whether the presence of PVCs at study baseline (1987-89) influenced the risk of incident stroke through 31st December 2004. PVCs were seen in 6.1% of the participants at baseline, and 729 (4.9%) had incident stroke. The unadjusted cumulative proportion of incident stroke in individuals with any PVC was 6.6% compared to 4.1% in those without PVC. The unadjusted hazard ratio (HR) of incident stroke in individuals with any PVC compared to those without any PVCs was 1.71 (95% Confidence Interval (CI) 1.33, 2.20).
Among individuals without hypertension and diabetes at baseline, PVCs were independently associated with incident stroke (HR: 1.72 (1.14, 2.59)). Among those with either diabetes or hypertension the presence of any PVCs did not increase the risk of stroke. The association was stronger for non-carotid embolic stroke than for thrombotic stroke and its magnitude increased with higher frequency of PVCs.
Conclusions
Frequent PVCs are associated with risk of incident stroke in participants free of hypertension and diabetes. This suggests that PVCs may contribute to atrio-ventricular remodeling or may be risk marker for incident stroke, particularly embolic stroke.
doi:10.1161/STROKEAHA.109.567800
PMCID: PMC2866170  PMID: 20167922
Stroke; Risk factors; Arrhythmia; Ventricular premature complexes; Atrial Fibrillation
23.  Electroanatomical Characteristics of Idiopathic Left Ventricular Tachycardia and Optimal Ablation Target during Sinus Rhythm: Significance of Preferential Conduction through Purkinje Fibers 
Yonsei Medical Journal  2012;53(2):279-288.
Purpose
We hypothesized that Purkinje potential and their preferential conduction to the left ventricle (LV) posteroseptum during sinus rhythm (SR) are part of reentrant circuits of idiopathic left ventricular tachycardia (ILVT) and reentry anchors to papillary muscle.
Materials and Methods
In 14 patients with ILVT (11 men, mean age 31.5±11.1 years), we compared Purkinje potential and preferential conduction during SR with VT by non-contact mapping (NCM). If clear Purkinje potential(SR) was observed in the LV posteroseptum and the earliest activation site (EA) of preferential conduction at SR (EASR) was well matched with that of VT (EAVT), EASR was targeted for radiofrequency catheter ablation (RFCA). Also, the anatomical locations of successful ablation sites were evaluated by echocardiography in five additional patients.
Results
1) All induced VTs exhibited clear Purkinje potential(VT) and preferential conduction in the LV posteroseptum. The Purkinje potential(VT) and EAVT was within 5.8±8.2 mm of EASR. However, the breakout sites of VT were separated by 30.2±12.6 mm from EAVT to the apical side. 2) Purkinje potential(SR) demonstrated a reversed polarity to Purkinje potential(VT), and the interval of Purkinje potential(SR)-QRS was longer than the interval of Purkinje potential(VT)-QRS (p<0.02) 3) RFCA targeting EASR eliminated VT in all patients without recurrence within 23.3±7.5 months, and the successful ablation site was discovered at the base of papillary muscle in the five additional (100%) patients.
Conclusion
NCM-guided localization of EASR with Purkinje potential(SR) matches well with EAVT with Purkinje potential(VT) and provides an effective target for RFCA, potentially at the base of papillary muscle in patients with ILVT.
doi:10.3349/ymj.2012.53.2.279
PMCID: PMC3282975  PMID: 22318814
Idiopathic left ventricular tachycardia; catheter ablation; non-contact map; Purkinje
24.  Feasibility of remote magnetic navigation for epicardial ablation 
Netherlands Heart Journal  2013;21(9):391-395.
Percutaneous epicardial mapping and ablation is an emerging method to treat ventricular tachycardias (VT), premature ventricular complexes (PVC), and accessory pathways. The use of a remote magnetic navigation system (MNS) could enhance precision and maintain safety. This multiple case history demonstrates the feasibility and safety of the MNS-guided epicardial approach in mapping and ablation of ischaemic VT, outflow tract PVCs, and a left-sided accessory pathway. All patients had previously undergone endocardial mapping for the same arrhythmia. MNS could present an advantage from more precise navigation for mapping and maintaining catheter stability during energy application.
doi:10.1007/s12471-013-0431-x
PMCID: PMC3751027  PMID: 23722429
Remote magnetic navigation; Epicardial mapping; Radiofrequency ablation
25.  Robust Detection of Premature Ventricular Contractions Using a Wave-Based Bayesian Framework 
Detection and classification of ventricular complexes from the electrocardiogram (ECG) is of considerable importance in Holter and critical care patient monitoring, being essential for the timely diagnosis of dangerous heart conditions. Accurate detection of premature ventricular contractions (PVCs) is particularly important in relation to life-threatening arrhythmias. In this paper, we introduce a model-based dynamic algorithm for tracking the ECG characteristic waveforms using an extended Kalman filter. The algorithm can work on single or multiple leads. A ‘polargram’ - a polar representation of the signal - is introduced, which is constructed using the Bayesian estimations of the state variables. The polargram allows the specification of a polar envelope for normal rhythms. Moreover, we propose a novel measure of signal fidelity by monitoring the covariance matrix of the innovation signals throughout the filtering procedure. PVCs are detected by simultaneous tracking the signal fidelity and the polar envelope. Five databases, including 40 records from MIT-BIH arrhythmia database, are used for differentiating normal, PVC, and other beats. Performance evaluation results show that the proposed method has an average detection accuracy of 99.10%, aggregate sensitivity of 98.77%, and aggregate positive predictivity of 97.47%. Furthermore, the method is capable of 100% accuracy for records that contain only PVCs and normal sinus beats. The results illustrate that the method can contribute to, and enhance the performance of clinical PVC detection.
doi:10.1109/TBME.2009.2031243
PMCID: PMC2927513  PMID: 19758851
Characteristic waves; Electrocardiogram (ECG); Extended Kalman filter (EKF); Premature ventricular contraction (PVC); Signal quality; Signal fidelity; Wave-based dynamical model

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