Journal of cardiovascular electrophysiology, Jan 27, 2014
Contact force sensing (CFS) technology improves acute pulmonary vein isolation durability; howeve... more Contact force sensing (CFS) technology improves acute pulmonary vein isolation durability; however, its impact on the clinical outcome of ablating atrial fibrillation (AF) is unknown. First time AF ablation procedures employing CFS from four centers were matched retrospectively to those without CFS in a 1:2 manner by type of AF. Freedom from atrial tachyarrhythmia was defined as the primary outcome measure, and fluoroscopy time the secondary outcome measure. Nineteen possible explanatory variables were tested in addition to CFS. A total of 600 AF ablation procedures (200 using CFS and 400 using non-CFS catheters) performed between 2010 and 2012 (46% paroxysmal, 36% persistent, 18% long-lasting persistent) were analyzed. The mean follow up duration was 11.4 ± 4.7 months - paroxysmal AF 11.2 ± 4.1 CFS vs. 11.3 ± 3.9 non-CFS (p = 0.745) - non-paroxysmal AF 10.4 ± 4.5 CFS vs. 11.9 ± 5.4 non-CFS (p = 0.015). The use of a CFS catheter independently predicted clinical success in ablating p...
Journal of Cardiovascular Electrophysiology, Mar 6, 2015
IntroductionContact force sensing (CFS) technology improves acute pulmonary vein isolation durabi... more IntroductionContact force sensing (CFS) technology improves acute pulmonary vein isolation durability; however, its impact on the clinical outcome of ablating atrial fibrillation (AF) is unknown.Contact force sensing (CFS) technology improves acute pulmonary vein isolation durability; however, its impact on the clinical outcome of ablating atrial fibrillation (AF) is unknown.Methods and ResultsFirst time AF ablation procedures employing CFS from 4 centers were matched retrospectively to those without CFS in a 1:2 manner by type of AF. Freedom from atrial tachyarrhythmia was defined as the primary outcome measure, and fluoroscopy time the secondary outcome measure. Nineteen possible explanatory variables were tested in addition to CFS. A total of 600 AF ablation procedures (200 using CFS and 400 using non-CFS catheters) performed between 2010 and 2012 (46% paroxysmal, 36% persistent, 18% long-lasting persistent) were analyzed. The mean follow-up duration was 11.4 ± 4.7 months—paroxysmal AF 11.2 ± 4.1 CFS versus 11.3 ± 3.9 non-CFS (P = 0.745)—nonparoxysmal AF 10.4 ± 4.5 CFS versus 11.9 ± 5.4 non-CFS (P = 0.015). The use of a CFS catheter independently predicted clinical success in ablating paroxysmal AF (HR 2.24 [95% CIs 1.29–3.90]; P = 0.004), but not nonparoxysmal AF (HR 0.73 [0.41–1.30]; P = 0.289) in a multivariate analysis that included follow-up duration. Among all cases, the use of CFS catheters was associated with reduced fluoroscopy time in multivariate analysis (reduction by 7.7 [5.0–10.5] minutes; P < 0.001). Complication rates were similar in both groups.First time AF ablation procedures employing CFS from 4 centers were matched retrospectively to those without CFS in a 1:2 manner by type of AF. Freedom from atrial tachyarrhythmia was defined as the primary outcome measure, and fluoroscopy time the secondary outcome measure. Nineteen possible explanatory variables were tested in addition to CFS. A total of 600 AF ablation procedures (200 using CFS and 400 using non-CFS catheters) performed between 2010 and 2012 (46% paroxysmal, 36% persistent, 18% long-lasting persistent) were analyzed. The mean follow-up duration was 11.4 ± 4.7 months—paroxysmal AF 11.2 ± 4.1 CFS versus 11.3 ± 3.9 non-CFS (P = 0.745)—nonparoxysmal AF 10.4 ± 4.5 CFS versus 11.9 ± 5.4 non-CFS (P = 0.015). The use of a CFS catheter independently predicted clinical success in ablating paroxysmal AF (HR 2.24 [95% CIs 1.29–3.90]; P = 0.004), but not nonparoxysmal AF (HR 0.73 [0.41–1.30]; P = 0.289) in a multivariate analysis that included follow-up duration. Among all cases, the use of CFS catheters was associated with reduced fluoroscopy time in multivariate analysis (reduction by 7.7 [5.0–10.5] minutes; P < 0.001). Complication rates were similar in both groups.ConclusionsAt medium-term follow-up, CFS catheter technology is associated with significantly improved outcome of first time catheter ablation of paroxysmal AF, but not nonparoxysmal AF. Fluoroscopy time was lower when CFS technology was employed in all types of AF ablation procedures.At medium-term follow-up, CFS catheter technology is associated with significantly improved outcome of first time catheter ablation of paroxysmal AF, but not nonparoxysmal AF. Fluoroscopy time was lower when CFS technology was employed in all types of AF ablation procedures.
Journal of Interventional Cardiac Electrophysiology, Oct 1, 2006
Objective To demonstrate that the use of a 20-pole catheter (Halo™) positioned around the tricusp... more Objective To demonstrate that the use of a 20-pole catheter (Halo™) positioned around the tricuspid valve annulus (TVA) is helpful in rapidly localising right free wall accessory pathways (AP), enhancing catheter stability during ablation, and leading to increased success in ablating these challenging pathways. Patients and methods Seven consecutive patients who underwent Halo-mapping of right-sided AP were studied. All but one had previously failed ablation. With a Halo catheter deployed at TVA, the accessory pathway location was rapidly identified using the sites of earliest atrial (A) activation during ventricular (V) pacing or orthodromic tachycardia, or earliest V-activation during sinus rhythm or A-pacing were identified. The stability of the ablation catheter was guided fluoroscopically (with reference to the stationary Halo), and electrically (contact artefact between the ablation catheter and Halo poles). Results AP locations were identified by the Halo (anterior in one patient, antero-lateral in one, lateral in two, and postero-lateral in three) where similar local VA/AV intervals were recorded at both the ablation catheter and Halo bipoles recording the shortest VA/AV intervals (four of seven patients), contact artefact between the ablation catheter and those Halo bipoles was seen (six of seven patients), or both (three of seven patients). All APs were ablated successfully after a mean RF duration of 5 ± 2 min, and 25 ± 17 min post Halo deployment without clinical recurrence at 12 ± 4 months follow-up. Conclusion A Halo positioned at the TVA can ease the localisation of right-sided AP, facilitate catheter stability during ablation, and guides successful ablation.
Heart rhythm : the official journal of the Heart Rhythm Society, Jan 8, 2015
More advanced Atrial Fibrillation (AF) is associated with lower success rates after pulmonary vei... more More advanced Atrial Fibrillation (AF) is associated with lower success rates after pulmonary vein isolation (PVI) and the optimal ablation strategy is uncertain. To assess the impact of additional linear ablation (lines) compared to PVI alone. In this multi-center randomised controlled trial, 122 patients (age 61.9±10.5years, left atrial diameter 43±6mm), with persistent (PeAF) or sustained (>12h) paroxysmal (SusPAF) AF with risk factors for atrial substrate were included and followed-up for 12 months. Randomisation was to PVI only or PVI+lines (left atrial roof, mitral and tricuspid isthmi). Holter monitoring was performed at 3, 6 and 12 months and according to symptoms. The primary outcome was atrial tachyarrhythmia recurrence ≥30s. Baseline characteristics were comparable between groups; 61% had PeAF and 39% SusPAF. Successful PVI was achieved for 98% of pulmonary veins and bidirectional block was obtained in 90% of lines. The primary endpoint occurred in 38% of the PVI+lines...
Recent advances in surgical techniques and understanding of the pathophysiology of atrial fibrill... more Recent advances in surgical techniques and understanding of the pathophysiology of atrial fibrillation has led to the development of a less invasive thoracoscopic surgical treatment including video-assisted bilateral pulmonary vein isolation using bipolar radiofrequency ablation clamps. More recently, the same operation became possible via a totally thoracoscopic approach. In this paper we describe technical aspects of the thoracoscopic approach to surgical treatment of AF and discuss its features, benefits and limitations. Furthermore, we present a new alternative technique of conduction testing using endoscopic multi-electrode recording catheters. An alternative electrophysiological mapping strategy involves a multi-electrode recording catheter designed primarily for percutaneous endocardial electrophysiologic mapping procedure. According to our initial experience, the recordings obtained from the multi-electrode catheters positioned around the pulmonary veins are more accurate th...
Circulation. Arrhythmia and electrophysiology, 2013
Ablation of persistent atrial fibrillation can be challenging, often involving not only pulmonary... more Ablation of persistent atrial fibrillation can be challenging, often involving not only pulmonary vein isolation (PVI) but also additional linear lesions and ablation of complex fractionated electrograms (CFE). We examined the impact of stepwise ablation on a human model of advanced atrial substrate of persistent atrial fibrillation in heart failure. In 30 patients with persistent atrial fibrillation and left ventricular ejection fraction ≤35%, high-density CFE maps were recorded biatrially at baseline, in the left atrium (LA) after PVI and linear lesions (roof and mitral isthmus), and biatrially after LA CFE ablation. Surface area of CFE (mean cycle length ≤120 ms) remote to PVI and linear lesions, defined as CFE area, was reduced after PVI (18.3±12.03 to 10.2±7.1 cm(2); P<0.001) and again after linear lesions (7.7±6.5 cm(2); P=0.006). Complete mitral isthmus block predicted greater CFE reduction (P=0.02). Right atrial CFE area was reduced by LA ablation, from 25.9±14.1 to 12.9±...
Journal of cardiovascular electrophysiology, Jan 27, 2014
Contact force sensing (CFS) technology improves acute pulmonary vein isolation durability; howeve... more Contact force sensing (CFS) technology improves acute pulmonary vein isolation durability; however, its impact on the clinical outcome of ablating atrial fibrillation (AF) is unknown. First time AF ablation procedures employing CFS from four centers were matched retrospectively to those without CFS in a 1:2 manner by type of AF. Freedom from atrial tachyarrhythmia was defined as the primary outcome measure, and fluoroscopy time the secondary outcome measure. Nineteen possible explanatory variables were tested in addition to CFS. A total of 600 AF ablation procedures (200 using CFS and 400 using non-CFS catheters) performed between 2010 and 2012 (46% paroxysmal, 36% persistent, 18% long-lasting persistent) were analyzed. The mean follow up duration was 11.4 ± 4.7 months - paroxysmal AF 11.2 ± 4.1 CFS vs. 11.3 ± 3.9 non-CFS (p = 0.745) - non-paroxysmal AF 10.4 ± 4.5 CFS vs. 11.9 ± 5.4 non-CFS (p = 0.015). The use of a CFS catheter independently predicted clinical success in ablating p...
Journal of the American College of Cardiology, 2013
Background: Atrial arrhythmias are associated with a well-documented risk of insitu thrombosis an... more Background: Atrial arrhythmias are associated with a well-documented risk of insitu thrombosis and embolism. Mechanical reasons including reduced atrial contractility and stagnation may contribute, alongside a possible prothrombotic state. Although anticoagulants reduce thromboembolic risk, patients remain at elevated risk compared to those without arrhythmia.
Journal of the American College of Cardiology, 2006
This study assessed the effects of carbenoxolone on human myocardial conduction and refractorines... more This study assessed the effects of carbenoxolone on human myocardial conduction and refractoriness. BACKGROUND Carbenoxolone, an antipeptic ulcer drug, has been shown to reduce gap junctional coupling without affecting cellular ion channels. Gap junctions (GJ) are considered to be determinants of cardiac action potential propagation. The effects of GJ uncoupling in the human heart are unknown.
Journal of the American College of Cardiology, 2013
This study sought to compare catheter ablation with rate control for persistent atrial fibrillati... more This study sought to compare catheter ablation with rate control for persistent atrial fibrillation (AF) in heart failure (HF).
Journal of Interventional Cardiac Electrophysiology, 2006
Objective To demonstrate that the use of a 20-pole catheter (Halo™) positioned around the tricusp... more Objective To demonstrate that the use of a 20-pole catheter (Halo™) positioned around the tricuspid valve annulus (TVA) is helpful in rapidly localising right free wall accessory pathways (AP), enhancing catheter stability during ablation, and leading to increased success in ablating these challenging pathways. Patients and methods Seven consecutive patients who underwent Halo-mapping of right-sided AP were studied. All but one had previously failed ablation. With a Halo catheter deployed at TVA, the accessory pathway location was rapidly identified using the sites of earliest atrial (A) activation during ventricular (V) pacing or orthodromic tachycardia, or earliest V-activation during sinus rhythm or A-pacing were identified. The stability of the ablation catheter was guided fluoroscopically (with reference to the stationary Halo), and electrically (contact artefact between the ablation catheter and Halo poles). Results AP locations were identified by the Halo (anterior in one patient, antero-lateral in one, lateral in two, and postero-lateral in three) where similar local VA/AV intervals were recorded at both the ablation catheter and Halo bipoles recording the shortest VA/AV intervals (four of seven patients), contact artefact between the ablation catheter and those Halo bipoles was seen (six of seven patients), or both (three of seven patients). All APs were ablated successfully after a mean RF duration of 5 ± 2 min, and 25 ± 17 min post Halo deployment without clinical recurrence at 12 ± 4 months follow-up. Conclusion A Halo positioned at the TVA can ease the localisation of right-sided AP, facilitate catheter stability during ablation, and guides successful ablation.
The Journal of Heart and Lung Transplantation, 2011
BACKGROUND: Permanent pacemaker implantation (PPM) early after cardiac transplantation has been s... more BACKGROUND: Permanent pacemaker implantation (PPM) early after cardiac transplantation has been shown not to predict a worse outcome. However, the requirement for pacing late after transplantation and its prognostic implications are not fully known. We describe the clinical indications, risk factors and long-term outcome in patients who required pacing early and late after transplantation. METHODS: The transplant database, medical records and pacing database/records were reviewed for all patients undergoing de novo orthotopic cardiac transplantation (n ϭ 389) at our institution between January 1995 and May 2006. RESULTS: A total of 48 patients (12.3%) received a pacemaker after transplantation. Of these patients, 30 were paced early, pre-hospital discharge (25 Ϯ 19 days post-transplantation), and 18 patients had late pacing (3.0 Ϯ 3.3 years post-transplantation). There were no differences in clinical characteristics, use of anti-arrhythmic drugs or length-of-stay post-transplantation between early and late groups. Early indications for pacing were more often sino-atrial (SA) disease (24 of 30, 80%), whereas atrio-ventricular (AV) disease was more likely to occur later (p ϭ 0.03). Risk factors for PPM included use of biatrial anastomosis (p ϭ 0.001) and donor age (p ϭ 0.002). Prior rejection was a univariate but not multivariate (p ϭ 0.09) predictor of the need for PPM. Development of cardiac allograft vasculopathy was not predictive. There was no significant difference in mortality between late and early PPM patients or between late PPM patients and the non-paced patients who survived transplantation and initial stay. CONCLUSIONS: Patients who required PPM late after orthotopic cardiac transplantation had a prognosis comparable to those paced early and those who did not require PPM. The independent risk factors for PPM were biatrial anastomosis and increasing donor age. SA-nodal dysfunction as an indication for PPM was more prevalent early after transplantation, whereas atrioventricular (AV) disease more commonly presented late. The requirement for pacing late after transplantation was not associated with rejection or cardiac allograft vasculopathy.
Introduction-In disease states such as heart failure, myocardial infarction and hypertrophy, chan... more Introduction-In disease states such as heart failure, myocardial infarction and hypertrophy, changes in the expression and location of Connexin43 (Cx43) occur (Cx43 remodeling), and may predispose to arrhythmias. Stretch may be an important stimulus to Cx43 remodeling; however, it has only been investigated in neonatal cell cultures, which have different physiological properties to adult myocytes. We hypothesized that localized stretch in vivo causes Cx43 remodeling, with associated changes in conduction, mediated by the renin/angiotensin system (RAS).
Background: Contact force (CF) sensing technology allows real time CF measurement during catheter... more Background: Contact force (CF) sensing technology allows real time CF measurement during catheter ablation. We hypothesised that the use of CF technology during pulmonary vein isolation (PVI) for atrial fibrillation (AF) would translate into lower acute pulmonary vein (PV) reconnection rates. Methods and results: Symptomatic AF patients were treated in two groups, 'unblinded' and 'blinded', each containing 20 patients undergoing first time PVI. An irrigated radiofrequency CF sensing catheter was used in both groups. In the 'unblinded' group, the operator could view the CF value during mapping and ablation in real time. In the 'blinded group', the operator was 'blinded' to this information during the procedure, although the data were recorded. All 80 PVs were successfully isolated with exit and entrance block re-tested after 1 h with adenosine. There was a significant association between blinding and the rate of acute PV reconnection. 17/80 (21%) of the PVs in the blinded subjects had a reconnection while 3/80 (4%) of the PVs in the unblinded subjects had a reconnection (p=0.001). Blinding the operator resulted in lower mean CF overall (11.6 g (10.5, 12.9 g) vs. 14.4 g (13.3, 15.7 g); p=0.002). Sites where applied CF was significantly lower than others were usually the sites where reconnection occurred: these were the ridge between the left upper PV and appendage, and the right carina. Conclusions: CF data identified key areas where CF was poor. These were the areas of acute reconnection. Availability of real time CF information during PVI was associated with a significantly lower acute pulmonary vein reconnection rate.
Background: Atrial tachyarrhythmias are a known complication late after Fontan operation. Limited... more Background: Atrial tachyarrhythmias are a known complication late after Fontan operation. Limited information is available on their prognostic value. Methods: All patients with previous Fontan operation followed at our institution since 1999 were identified from the electronic database and included in this study. Demographic and clinical characteristics including history of atrial tachyarrhythmias were recorded at the earliest full clinical assessment and patients were followed thereafter for all-cause mortality and hospitalization. Results: A total of 98 patients, mean age 31.5 ± 8.9 years, 43.8% male, 31.6% with a total cavopulmonary connection (TCPC) were identified. A history of atrial tachyarrhythmia was present at baseline in 60.2% of patients who were older (33.0 ± 8.3 vs 29.1 ± 9.4 years, p = 0.002), less likely to have a TCPC (13.5% vs 58.9%, p b 0.001), and more symptomatic in terms of NYHA class (51.9% vs 26.7%, p = 0.007) compared to arrhythmia-free patients. During a median follow-up of 6.7 years 18 patients died and 64 patients were hospitalized. Even after adjustment for baseline clinical characteristics, atrial tachyarrhythmia was an independent predictor of death (propensity score adjusted HR 9.35, 95% CI: 1.10-79.18, p = 0.04, c-statistic 0.88) and composite of death or hospitalization (propensity score adjusted HR 5.00, 95% CI: 2.47-10.09, p b 0.0001). Conclusions: In adult patients with a Fontan-type operation, the presence of atrial tachyarrhythmias is associated with higher morbidity and mortality at mid-term follow-up. Whether early arrhythmia targeting intervention may improve clinical outcome needs to be studied in a prospective manner.
Background: A canine model of myocardial infarction (MI) has demonstrated the impact of remodelin... more Background: A canine model of myocardial infarction (MI) has demonstrated the impact of remodeling of gap-junctional distribution on impulse conduction and arrhythmias involving reentry in the healing epicardial border zone. We have developed a murine model of inducible ventricular tachycardia (VT) and defined its anatomical and electrophysiological properties so that future studies could use transgenic methodology for investigating the role of gap junction remodeling in causing arrhythmias. Method: We determined the inducibility of VT in mice in the absence (Sham-mice, nϭ16) or presence (MI-mice, nϭ46) of healing MI using programmed stimulation protocols 3 days after ligation of the left anterior descending artery. Infarct size (nϭ31) was measured using the tetrazolium method and calculated as a percentage of total left ventricle volume. 3 hearts of MI-mice were sequentially sectioned and examined for standard histology and connexin43 (Cx43) immunohistochemistry. Results: There was significant difference (PϽ0.001) in the number of MI-mice (21, 46%) versus Sham-mice (1, 6%) that exhibited VT. The range of number of beats in VT was from 9 to 702 beats. Mean infarct size in MI-mice with VT was 26.71Ϯ3%, in MI-mice without VT was 31.19Ϯ3.3%. The relationship between VT inducibility and infarct size was not significant. The histological and immunofluorescent study revealed the presence of infarction with epicardial and endocardial rims of surviving tissue. There was redistribution of Cx43 labeling to the lateral cell membrane in all areas overlying and immediately adjacent to infarcts. Conclusion: MI-mice exhibit enhanced arrhythmogenesis in the setting of healing MI 3 days after ligation of the left anterior descending artery in which there is a surviving epicardial border zone showing gap junction redistribution. The role of gap junction remodeling can therefore be studied in transgenic mice in which remodeling is prevented.
Reentrant circuits causing tachycardia (VT) in the canine infarcted heart have a figure-8 activat... more Reentrant circuits causing tachycardia (VT) in the canine infarcted heart have a figure-8 activation pattern with a central (CCP) and an outer pathway (OP). In the OP, Cx43 is located at the intercalated disks but side-to-side gap junction conductance (Gj) is reduced by 90% (end-to-end Gj is normal). End-to-end and side-to-side Gj in the CCP are both normal but Cx43 redistributes along the lateral membrane. Remodeling of Na channel causes a reduction of I Na in both OP and CCP with a larger reduction in the CCP. To study the effect of gap junction remodeling on impulse propagation, we measured longitudinal (CVL) and transverse (CVT) conduction velocities and anisotropic ratio (ANR) in normal LV and in the OP and CCP of infarcted hearts (see . CCP and OP were localized by electrical mapping during VT (electrode size 9x8 cm 2 ; resolution 5mm). After VT was stopped, CVL and CVT were measured in the specific regions during stimulation (electrode size 24x19 mm 2 ; resolution 1.25mm). CVT in the OP was slower than in normal LV which reflects the decrease in side-to-side Gj; CVL was not different and consequently ANR increased. ANR in the CCP was the same as in normal LV which reflects the normal end-to-end and side-to-side Gj. CVL in the CCP is slower than in the OP and normal LV which is consistent with the effects of Na channel remodeling of this substrate. However, CVT in the OP and CCP do not differ, which is unexpected because the effects of Na channel remodeling are not directionally dependent. Therefore, we suggest that gap junction remodeling in the CCP partially compensates for the reduction in CVT caused by Na channel remodeling.
Journal of cardiovascular electrophysiology, Jan 27, 2014
Contact force sensing (CFS) technology improves acute pulmonary vein isolation durability; howeve... more Contact force sensing (CFS) technology improves acute pulmonary vein isolation durability; however, its impact on the clinical outcome of ablating atrial fibrillation (AF) is unknown. First time AF ablation procedures employing CFS from four centers were matched retrospectively to those without CFS in a 1:2 manner by type of AF. Freedom from atrial tachyarrhythmia was defined as the primary outcome measure, and fluoroscopy time the secondary outcome measure. Nineteen possible explanatory variables were tested in addition to CFS. A total of 600 AF ablation procedures (200 using CFS and 400 using non-CFS catheters) performed between 2010 and 2012 (46% paroxysmal, 36% persistent, 18% long-lasting persistent) were analyzed. The mean follow up duration was 11.4 ± 4.7 months - paroxysmal AF 11.2 ± 4.1 CFS vs. 11.3 ± 3.9 non-CFS (p = 0.745) - non-paroxysmal AF 10.4 ± 4.5 CFS vs. 11.9 ± 5.4 non-CFS (p = 0.015). The use of a CFS catheter independently predicted clinical success in ablating p...
Journal of Cardiovascular Electrophysiology, Mar 6, 2015
IntroductionContact force sensing (CFS) technology improves acute pulmonary vein isolation durabi... more IntroductionContact force sensing (CFS) technology improves acute pulmonary vein isolation durability; however, its impact on the clinical outcome of ablating atrial fibrillation (AF) is unknown.Contact force sensing (CFS) technology improves acute pulmonary vein isolation durability; however, its impact on the clinical outcome of ablating atrial fibrillation (AF) is unknown.Methods and ResultsFirst time AF ablation procedures employing CFS from 4 centers were matched retrospectively to those without CFS in a 1:2 manner by type of AF. Freedom from atrial tachyarrhythmia was defined as the primary outcome measure, and fluoroscopy time the secondary outcome measure. Nineteen possible explanatory variables were tested in addition to CFS. A total of 600 AF ablation procedures (200 using CFS and 400 using non-CFS catheters) performed between 2010 and 2012 (46% paroxysmal, 36% persistent, 18% long-lasting persistent) were analyzed. The mean follow-up duration was 11.4 ± 4.7 months—paroxysmal AF 11.2 ± 4.1 CFS versus 11.3 ± 3.9 non-CFS (P = 0.745)—nonparoxysmal AF 10.4 ± 4.5 CFS versus 11.9 ± 5.4 non-CFS (P = 0.015). The use of a CFS catheter independently predicted clinical success in ablating paroxysmal AF (HR 2.24 [95% CIs 1.29–3.90]; P = 0.004), but not nonparoxysmal AF (HR 0.73 [0.41–1.30]; P = 0.289) in a multivariate analysis that included follow-up duration. Among all cases, the use of CFS catheters was associated with reduced fluoroscopy time in multivariate analysis (reduction by 7.7 [5.0–10.5] minutes; P < 0.001). Complication rates were similar in both groups.First time AF ablation procedures employing CFS from 4 centers were matched retrospectively to those without CFS in a 1:2 manner by type of AF. Freedom from atrial tachyarrhythmia was defined as the primary outcome measure, and fluoroscopy time the secondary outcome measure. Nineteen possible explanatory variables were tested in addition to CFS. A total of 600 AF ablation procedures (200 using CFS and 400 using non-CFS catheters) performed between 2010 and 2012 (46% paroxysmal, 36% persistent, 18% long-lasting persistent) were analyzed. The mean follow-up duration was 11.4 ± 4.7 months—paroxysmal AF 11.2 ± 4.1 CFS versus 11.3 ± 3.9 non-CFS (P = 0.745)—nonparoxysmal AF 10.4 ± 4.5 CFS versus 11.9 ± 5.4 non-CFS (P = 0.015). The use of a CFS catheter independently predicted clinical success in ablating paroxysmal AF (HR 2.24 [95% CIs 1.29–3.90]; P = 0.004), but not nonparoxysmal AF (HR 0.73 [0.41–1.30]; P = 0.289) in a multivariate analysis that included follow-up duration. Among all cases, the use of CFS catheters was associated with reduced fluoroscopy time in multivariate analysis (reduction by 7.7 [5.0–10.5] minutes; P < 0.001). Complication rates were similar in both groups.ConclusionsAt medium-term follow-up, CFS catheter technology is associated with significantly improved outcome of first time catheter ablation of paroxysmal AF, but not nonparoxysmal AF. Fluoroscopy time was lower when CFS technology was employed in all types of AF ablation procedures.At medium-term follow-up, CFS catheter technology is associated with significantly improved outcome of first time catheter ablation of paroxysmal AF, but not nonparoxysmal AF. Fluoroscopy time was lower when CFS technology was employed in all types of AF ablation procedures.
Journal of Interventional Cardiac Electrophysiology, Oct 1, 2006
Objective To demonstrate that the use of a 20-pole catheter (Halo™) positioned around the tricusp... more Objective To demonstrate that the use of a 20-pole catheter (Halo™) positioned around the tricuspid valve annulus (TVA) is helpful in rapidly localising right free wall accessory pathways (AP), enhancing catheter stability during ablation, and leading to increased success in ablating these challenging pathways. Patients and methods Seven consecutive patients who underwent Halo-mapping of right-sided AP were studied. All but one had previously failed ablation. With a Halo catheter deployed at TVA, the accessory pathway location was rapidly identified using the sites of earliest atrial (A) activation during ventricular (V) pacing or orthodromic tachycardia, or earliest V-activation during sinus rhythm or A-pacing were identified. The stability of the ablation catheter was guided fluoroscopically (with reference to the stationary Halo), and electrically (contact artefact between the ablation catheter and Halo poles). Results AP locations were identified by the Halo (anterior in one patient, antero-lateral in one, lateral in two, and postero-lateral in three) where similar local VA/AV intervals were recorded at both the ablation catheter and Halo bipoles recording the shortest VA/AV intervals (four of seven patients), contact artefact between the ablation catheter and those Halo bipoles was seen (six of seven patients), or both (three of seven patients). All APs were ablated successfully after a mean RF duration of 5 ± 2 min, and 25 ± 17 min post Halo deployment without clinical recurrence at 12 ± 4 months follow-up. Conclusion A Halo positioned at the TVA can ease the localisation of right-sided AP, facilitate catheter stability during ablation, and guides successful ablation.
Heart rhythm : the official journal of the Heart Rhythm Society, Jan 8, 2015
More advanced Atrial Fibrillation (AF) is associated with lower success rates after pulmonary vei... more More advanced Atrial Fibrillation (AF) is associated with lower success rates after pulmonary vein isolation (PVI) and the optimal ablation strategy is uncertain. To assess the impact of additional linear ablation (lines) compared to PVI alone. In this multi-center randomised controlled trial, 122 patients (age 61.9±10.5years, left atrial diameter 43±6mm), with persistent (PeAF) or sustained (>12h) paroxysmal (SusPAF) AF with risk factors for atrial substrate were included and followed-up for 12 months. Randomisation was to PVI only or PVI+lines (left atrial roof, mitral and tricuspid isthmi). Holter monitoring was performed at 3, 6 and 12 months and according to symptoms. The primary outcome was atrial tachyarrhythmia recurrence ≥30s. Baseline characteristics were comparable between groups; 61% had PeAF and 39% SusPAF. Successful PVI was achieved for 98% of pulmonary veins and bidirectional block was obtained in 90% of lines. The primary endpoint occurred in 38% of the PVI+lines...
Recent advances in surgical techniques and understanding of the pathophysiology of atrial fibrill... more Recent advances in surgical techniques and understanding of the pathophysiology of atrial fibrillation has led to the development of a less invasive thoracoscopic surgical treatment including video-assisted bilateral pulmonary vein isolation using bipolar radiofrequency ablation clamps. More recently, the same operation became possible via a totally thoracoscopic approach. In this paper we describe technical aspects of the thoracoscopic approach to surgical treatment of AF and discuss its features, benefits and limitations. Furthermore, we present a new alternative technique of conduction testing using endoscopic multi-electrode recording catheters. An alternative electrophysiological mapping strategy involves a multi-electrode recording catheter designed primarily for percutaneous endocardial electrophysiologic mapping procedure. According to our initial experience, the recordings obtained from the multi-electrode catheters positioned around the pulmonary veins are more accurate th...
Circulation. Arrhythmia and electrophysiology, 2013
Ablation of persistent atrial fibrillation can be challenging, often involving not only pulmonary... more Ablation of persistent atrial fibrillation can be challenging, often involving not only pulmonary vein isolation (PVI) but also additional linear lesions and ablation of complex fractionated electrograms (CFE). We examined the impact of stepwise ablation on a human model of advanced atrial substrate of persistent atrial fibrillation in heart failure. In 30 patients with persistent atrial fibrillation and left ventricular ejection fraction ≤35%, high-density CFE maps were recorded biatrially at baseline, in the left atrium (LA) after PVI and linear lesions (roof and mitral isthmus), and biatrially after LA CFE ablation. Surface area of CFE (mean cycle length ≤120 ms) remote to PVI and linear lesions, defined as CFE area, was reduced after PVI (18.3±12.03 to 10.2±7.1 cm(2); P<0.001) and again after linear lesions (7.7±6.5 cm(2); P=0.006). Complete mitral isthmus block predicted greater CFE reduction (P=0.02). Right atrial CFE area was reduced by LA ablation, from 25.9±14.1 to 12.9±...
Journal of cardiovascular electrophysiology, Jan 27, 2014
Contact force sensing (CFS) technology improves acute pulmonary vein isolation durability; howeve... more Contact force sensing (CFS) technology improves acute pulmonary vein isolation durability; however, its impact on the clinical outcome of ablating atrial fibrillation (AF) is unknown. First time AF ablation procedures employing CFS from four centers were matched retrospectively to those without CFS in a 1:2 manner by type of AF. Freedom from atrial tachyarrhythmia was defined as the primary outcome measure, and fluoroscopy time the secondary outcome measure. Nineteen possible explanatory variables were tested in addition to CFS. A total of 600 AF ablation procedures (200 using CFS and 400 using non-CFS catheters) performed between 2010 and 2012 (46% paroxysmal, 36% persistent, 18% long-lasting persistent) were analyzed. The mean follow up duration was 11.4 ± 4.7 months - paroxysmal AF 11.2 ± 4.1 CFS vs. 11.3 ± 3.9 non-CFS (p = 0.745) - non-paroxysmal AF 10.4 ± 4.5 CFS vs. 11.9 ± 5.4 non-CFS (p = 0.015). The use of a CFS catheter independently predicted clinical success in ablating p...
Journal of the American College of Cardiology, 2013
Background: Atrial arrhythmias are associated with a well-documented risk of insitu thrombosis an... more Background: Atrial arrhythmias are associated with a well-documented risk of insitu thrombosis and embolism. Mechanical reasons including reduced atrial contractility and stagnation may contribute, alongside a possible prothrombotic state. Although anticoagulants reduce thromboembolic risk, patients remain at elevated risk compared to those without arrhythmia.
Journal of the American College of Cardiology, 2006
This study assessed the effects of carbenoxolone on human myocardial conduction and refractorines... more This study assessed the effects of carbenoxolone on human myocardial conduction and refractoriness. BACKGROUND Carbenoxolone, an antipeptic ulcer drug, has been shown to reduce gap junctional coupling without affecting cellular ion channels. Gap junctions (GJ) are considered to be determinants of cardiac action potential propagation. The effects of GJ uncoupling in the human heart are unknown.
Journal of the American College of Cardiology, 2013
This study sought to compare catheter ablation with rate control for persistent atrial fibrillati... more This study sought to compare catheter ablation with rate control for persistent atrial fibrillation (AF) in heart failure (HF).
Journal of Interventional Cardiac Electrophysiology, 2006
Objective To demonstrate that the use of a 20-pole catheter (Halo™) positioned around the tricusp... more Objective To demonstrate that the use of a 20-pole catheter (Halo™) positioned around the tricuspid valve annulus (TVA) is helpful in rapidly localising right free wall accessory pathways (AP), enhancing catheter stability during ablation, and leading to increased success in ablating these challenging pathways. Patients and methods Seven consecutive patients who underwent Halo-mapping of right-sided AP were studied. All but one had previously failed ablation. With a Halo catheter deployed at TVA, the accessory pathway location was rapidly identified using the sites of earliest atrial (A) activation during ventricular (V) pacing or orthodromic tachycardia, or earliest V-activation during sinus rhythm or A-pacing were identified. The stability of the ablation catheter was guided fluoroscopically (with reference to the stationary Halo), and electrically (contact artefact between the ablation catheter and Halo poles). Results AP locations were identified by the Halo (anterior in one patient, antero-lateral in one, lateral in two, and postero-lateral in three) where similar local VA/AV intervals were recorded at both the ablation catheter and Halo bipoles recording the shortest VA/AV intervals (four of seven patients), contact artefact between the ablation catheter and those Halo bipoles was seen (six of seven patients), or both (three of seven patients). All APs were ablated successfully after a mean RF duration of 5 ± 2 min, and 25 ± 17 min post Halo deployment without clinical recurrence at 12 ± 4 months follow-up. Conclusion A Halo positioned at the TVA can ease the localisation of right-sided AP, facilitate catheter stability during ablation, and guides successful ablation.
The Journal of Heart and Lung Transplantation, 2011
BACKGROUND: Permanent pacemaker implantation (PPM) early after cardiac transplantation has been s... more BACKGROUND: Permanent pacemaker implantation (PPM) early after cardiac transplantation has been shown not to predict a worse outcome. However, the requirement for pacing late after transplantation and its prognostic implications are not fully known. We describe the clinical indications, risk factors and long-term outcome in patients who required pacing early and late after transplantation. METHODS: The transplant database, medical records and pacing database/records were reviewed for all patients undergoing de novo orthotopic cardiac transplantation (n ϭ 389) at our institution between January 1995 and May 2006. RESULTS: A total of 48 patients (12.3%) received a pacemaker after transplantation. Of these patients, 30 were paced early, pre-hospital discharge (25 Ϯ 19 days post-transplantation), and 18 patients had late pacing (3.0 Ϯ 3.3 years post-transplantation). There were no differences in clinical characteristics, use of anti-arrhythmic drugs or length-of-stay post-transplantation between early and late groups. Early indications for pacing were more often sino-atrial (SA) disease (24 of 30, 80%), whereas atrio-ventricular (AV) disease was more likely to occur later (p ϭ 0.03). Risk factors for PPM included use of biatrial anastomosis (p ϭ 0.001) and donor age (p ϭ 0.002). Prior rejection was a univariate but not multivariate (p ϭ 0.09) predictor of the need for PPM. Development of cardiac allograft vasculopathy was not predictive. There was no significant difference in mortality between late and early PPM patients or between late PPM patients and the non-paced patients who survived transplantation and initial stay. CONCLUSIONS: Patients who required PPM late after orthotopic cardiac transplantation had a prognosis comparable to those paced early and those who did not require PPM. The independent risk factors for PPM were biatrial anastomosis and increasing donor age. SA-nodal dysfunction as an indication for PPM was more prevalent early after transplantation, whereas atrioventricular (AV) disease more commonly presented late. The requirement for pacing late after transplantation was not associated with rejection or cardiac allograft vasculopathy.
Introduction-In disease states such as heart failure, myocardial infarction and hypertrophy, chan... more Introduction-In disease states such as heart failure, myocardial infarction and hypertrophy, changes in the expression and location of Connexin43 (Cx43) occur (Cx43 remodeling), and may predispose to arrhythmias. Stretch may be an important stimulus to Cx43 remodeling; however, it has only been investigated in neonatal cell cultures, which have different physiological properties to adult myocytes. We hypothesized that localized stretch in vivo causes Cx43 remodeling, with associated changes in conduction, mediated by the renin/angiotensin system (RAS).
Background: Contact force (CF) sensing technology allows real time CF measurement during catheter... more Background: Contact force (CF) sensing technology allows real time CF measurement during catheter ablation. We hypothesised that the use of CF technology during pulmonary vein isolation (PVI) for atrial fibrillation (AF) would translate into lower acute pulmonary vein (PV) reconnection rates. Methods and results: Symptomatic AF patients were treated in two groups, 'unblinded' and 'blinded', each containing 20 patients undergoing first time PVI. An irrigated radiofrequency CF sensing catheter was used in both groups. In the 'unblinded' group, the operator could view the CF value during mapping and ablation in real time. In the 'blinded group', the operator was 'blinded' to this information during the procedure, although the data were recorded. All 80 PVs were successfully isolated with exit and entrance block re-tested after 1 h with adenosine. There was a significant association between blinding and the rate of acute PV reconnection. 17/80 (21%) of the PVs in the blinded subjects had a reconnection while 3/80 (4%) of the PVs in the unblinded subjects had a reconnection (p=0.001). Blinding the operator resulted in lower mean CF overall (11.6 g (10.5, 12.9 g) vs. 14.4 g (13.3, 15.7 g); p=0.002). Sites where applied CF was significantly lower than others were usually the sites where reconnection occurred: these were the ridge between the left upper PV and appendage, and the right carina. Conclusions: CF data identified key areas where CF was poor. These were the areas of acute reconnection. Availability of real time CF information during PVI was associated with a significantly lower acute pulmonary vein reconnection rate.
Background: Atrial tachyarrhythmias are a known complication late after Fontan operation. Limited... more Background: Atrial tachyarrhythmias are a known complication late after Fontan operation. Limited information is available on their prognostic value. Methods: All patients with previous Fontan operation followed at our institution since 1999 were identified from the electronic database and included in this study. Demographic and clinical characteristics including history of atrial tachyarrhythmias were recorded at the earliest full clinical assessment and patients were followed thereafter for all-cause mortality and hospitalization. Results: A total of 98 patients, mean age 31.5 ± 8.9 years, 43.8% male, 31.6% with a total cavopulmonary connection (TCPC) were identified. A history of atrial tachyarrhythmia was present at baseline in 60.2% of patients who were older (33.0 ± 8.3 vs 29.1 ± 9.4 years, p = 0.002), less likely to have a TCPC (13.5% vs 58.9%, p b 0.001), and more symptomatic in terms of NYHA class (51.9% vs 26.7%, p = 0.007) compared to arrhythmia-free patients. During a median follow-up of 6.7 years 18 patients died and 64 patients were hospitalized. Even after adjustment for baseline clinical characteristics, atrial tachyarrhythmia was an independent predictor of death (propensity score adjusted HR 9.35, 95% CI: 1.10-79.18, p = 0.04, c-statistic 0.88) and composite of death or hospitalization (propensity score adjusted HR 5.00, 95% CI: 2.47-10.09, p b 0.0001). Conclusions: In adult patients with a Fontan-type operation, the presence of atrial tachyarrhythmias is associated with higher morbidity and mortality at mid-term follow-up. Whether early arrhythmia targeting intervention may improve clinical outcome needs to be studied in a prospective manner.
Background: A canine model of myocardial infarction (MI) has demonstrated the impact of remodelin... more Background: A canine model of myocardial infarction (MI) has demonstrated the impact of remodeling of gap-junctional distribution on impulse conduction and arrhythmias involving reentry in the healing epicardial border zone. We have developed a murine model of inducible ventricular tachycardia (VT) and defined its anatomical and electrophysiological properties so that future studies could use transgenic methodology for investigating the role of gap junction remodeling in causing arrhythmias. Method: We determined the inducibility of VT in mice in the absence (Sham-mice, nϭ16) or presence (MI-mice, nϭ46) of healing MI using programmed stimulation protocols 3 days after ligation of the left anterior descending artery. Infarct size (nϭ31) was measured using the tetrazolium method and calculated as a percentage of total left ventricle volume. 3 hearts of MI-mice were sequentially sectioned and examined for standard histology and connexin43 (Cx43) immunohistochemistry. Results: There was significant difference (PϽ0.001) in the number of MI-mice (21, 46%) versus Sham-mice (1, 6%) that exhibited VT. The range of number of beats in VT was from 9 to 702 beats. Mean infarct size in MI-mice with VT was 26.71Ϯ3%, in MI-mice without VT was 31.19Ϯ3.3%. The relationship between VT inducibility and infarct size was not significant. The histological and immunofluorescent study revealed the presence of infarction with epicardial and endocardial rims of surviving tissue. There was redistribution of Cx43 labeling to the lateral cell membrane in all areas overlying and immediately adjacent to infarcts. Conclusion: MI-mice exhibit enhanced arrhythmogenesis in the setting of healing MI 3 days after ligation of the left anterior descending artery in which there is a surviving epicardial border zone showing gap junction redistribution. The role of gap junction remodeling can therefore be studied in transgenic mice in which remodeling is prevented.
Reentrant circuits causing tachycardia (VT) in the canine infarcted heart have a figure-8 activat... more Reentrant circuits causing tachycardia (VT) in the canine infarcted heart have a figure-8 activation pattern with a central (CCP) and an outer pathway (OP). In the OP, Cx43 is located at the intercalated disks but side-to-side gap junction conductance (Gj) is reduced by 90% (end-to-end Gj is normal). End-to-end and side-to-side Gj in the CCP are both normal but Cx43 redistributes along the lateral membrane. Remodeling of Na channel causes a reduction of I Na in both OP and CCP with a larger reduction in the CCP. To study the effect of gap junction remodeling on impulse propagation, we measured longitudinal (CVL) and transverse (CVT) conduction velocities and anisotropic ratio (ANR) in normal LV and in the OP and CCP of infarcted hearts (see . CCP and OP were localized by electrical mapping during VT (electrode size 9x8 cm 2 ; resolution 5mm). After VT was stopped, CVL and CVT were measured in the specific regions during stimulation (electrode size 24x19 mm 2 ; resolution 1.25mm). CVT in the OP was slower than in normal LV which reflects the decrease in side-to-side Gj; CVL was not different and consequently ANR increased. ANR in the CCP was the same as in normal LV which reflects the normal end-to-end and side-to-side Gj. CVL in the CCP is slower than in the OP and normal LV which is consistent with the effects of Na channel remodeling of this substrate. However, CVT in the OP and CCP do not differ, which is unexpected because the effects of Na channel remodeling are not directionally dependent. Therefore, we suggest that gap junction remodeling in the CCP partially compensates for the reduction in CVT caused by Na channel remodeling.
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Papers by Wajid Hussain