Cardiovasc Electrophysiol Research Articles

Is There a Potential Benefit to Increased Irrigation Channels During Radiofrequency Ablation? Results From a Two-Center Prospective Randomized Study

Open irrigation during radiofrequency (RF) application allows a higher power delivery in the setting of temperature-controlled ablation, without causing blood clots. This study sought to evaluate the clinical value of the additional 6 supplementary channels at the proximal catheter tip compared to a standard irrigated RF catheter with 6 conventional channels present at the distal tip only. Ninety-five consecutive patients were prospectively randomized to cavotricuspid isthmus ablation using an 3.5 mm tip ablation catheter with 6 distal irrigation channels (6C; 48 patients) or an 4 mm tip ablation catheter with 12 irrigation channels (12C; 47 patients) disposed at the distal (6 channels) and proximal (6 additional channels) catheter tip. There was no significant difference between the 12C and the 6C irrigated-tip catheter concerning the total procedural duration, the RF duration, the fluoroscopic duration, and the amount of irrigation. Conversely, there were significantly more patients who experienced at least one steam pop while using the 12C as compared to the 6C irrigated-tip catheter (0% vs 13%, respectively, P = 0.018). The addition of proximal irrigation holes at the catheter tip do not facilitate lesion formation during RF ablation, but significantly increases the risk of steam pop. This is probably the consequence of an increase distortion of the temperature feedback.

Hemoptysis After Pulmonary Vein Isolation with a Cryoballoon: An Analysis of the Potential Etiology

In a series of 359 cryoballoon ablations with a complete registry of complications, clinically important hemoptysis requiring readmission was observed in 2 patients. One patient had preexisting bronchiectasis; the other had no previous history of pulmonary disease. In the first patient the guiding wire was very distal in one of the veins and exceptional low freezing temperatures were recorded in the left inferior pulmonary vein. Similarly, in the second patient exceptional low freezing temperatures were recorded in all 4 veins. Four additional patients mentioned hemoptysis at the 3-month follow-up visit, which resolved after temporary cessation of anticoagulation. Hemoptysis can occur after cryoballoon ablation for several reasons, especially when a stringent anticoagulation regimen is adhered to, and when occlusion is associated with very low freezing temperatures.

Effect of Limb Lead Electrodes Location on ECG and Localization of Idiopathic Outflow Tract Tachycardia: A Prospective Study

Different kinds of the surface ECG limb electrode positions may affect the limb lead vector and therefore the accuracy of the 12-lead ECG in localization of outflow tract ventricular tachycardia (OTVT). This study was intended to evaluate and compare the accuracy of the standard and the modified 12-lead ECG for localization of OTVT using the current published criteria. Twenty consecutive patients (10 men, mean age, 51.6 ± 13.4 years) with OT-VT were included. A standard ECG with the distal placement of the limb lead electrodes and a modified ECG with the limb electrodes placed on the torso were recorded during the OT-VT and were used for localization by 2 electrophysiologists who were blinded to the successful ablation site to compare the accuracy of the 2 ECGs. The R wave amplitude during OT-VT in lead I of the standard 12-lead ECG was significantly higher compared to the modified surface ECG (0.225 ± 0.145 mV vs 0.139 ± 0.111 mV, P = 0.032). The S wave in aVR during OT-VT was significantly more negative compared to the modified surface ECG (-0.682 ± 0.182 mV vs -0.527 ± 0.228 mV, P = 0.017). The rate of accurate localization of the successful ablation sites in the anterior versus posterior outflow tract by the 2 observers using standard ECG (70% and 80%) were higher compared to modified ECG (50% and 60%, P = 0.042). The R wave amplitude in lead I and the depth of the S wave amplitude in lead aVR of the standard surface ECG during OT-VT is significantly larger compared to the modified surface ECG. As the QRS morphology of the OT-VT is usually the first clue to the possible site of successful ablation, the standard 12-lead ECG should be used for more accurate localization of the origin of the OT-VT.

Approach to the Catheter Ablation Technique of Paroxysmal and Persistent Atrial Fibrillation: A Meta-Analysis of the Randomized Controlled Trials

Several randomized controlled trials (RCTs) have been published to investigate the optimal techniques for atrial fibrillation (AF) ablation. Many of these are small in number and include both paroxysmal and persistent AF; however, the techniques for each of these types of AF may differ. We searched MEDLINE, EMBASE, and the Cochrane Controlled Trials Register for RCTs evaluating AF ablation for either paroxysmal or persistent AF. The primary endpoint was freedom from AF after a single procedure. A total of 35 unique randomized controlled trials were found to fulfill the criteria. A significant degree of heterogeneity was present given the differing sample sizes, populations studied, and outcomes. Radiofrequency ablation (RFA) was found to be favorable in prevention of AF over antiarrhythmic drugs (AADs) in either paroxysmal (5 studies, RR 2.26; 95% CI 1.74, 2.94) or persistent AF (5 studies, RR 3.20; 95% CI 1.29, 8.41). When comparing specific techniques, wide-area PVI appeared to offer the most benefit for both paroxysmal (6 studies, RR 0.78; 95% CI 0.63, 0.97) and persistent AF (3 studies, RR 0.64; 95% CI 0.43, 0.94). CFE ablation provided only benefit for persistent AF when combined with antral PVI (4 studies, RR 0.55; 95% CI 0.34, 0.87). Despite significant methodological limitations, it appears that additional ablations beyond PVI are necessary for persistent AF but not proven for paroxysmal AF. The optimal technique for persistent AF, however, deserves a further study, in the setting of a large, randomized controlled trial.

Cavotricuspid Isthmus Ablation Guided by Electroanatomic Mapping in a Patient with a Mechanical Tricuspid Valve Replacement After a Total Correction of Tetralogy of Fallot

Atrial arrhythmias are a common sequel after surgery for congenital heart disease, and often eventually cause late morbidity and mortality. Nowadays, percutaneous catheter ablation of atrial flutter (AFL) is widely practised, and is highly successful and safe. Patients with a tricuspid valve replacement (TVR) represent a distinct group for whom the appropriate nonpharmacologic therapy for AFL has not yet been established. We report a case of a 55-year-old woman with a history of a total correction of tetralogy of Fallot (ToF) who developed AFL before and after receiving a tricuspid valve prosthesis. Based on the results of the activation mapping, counterclockwise and clockwise AFL were identified. Completion of a cavotricuspid isthmus (CTI) line on the atrial side successfully terminated the AFL, with resumption of sinus rhythm. Guided by a 3D mapping system, CTI ablation is feasible and safe in patients with a prosthetic tricuspid valve.

Our Approach to Management of Patients With Pulmonary Vein Stenosis Following AF Ablation

Despite advances in the approach to pulmonary vein isolation, pulmonary vein stenosis remains an important morbid complication affecting approximately 1.3% of procedures. Patients with symptomatic pulmonary vein stenosis are typically referred for intervention with either balloon angioplasty or stenting. A significant portion of patients with severe pulmonary vein stenosis are asymptomatic and are identified only if routine screening is preformed following ablation. Based on available evidence, CT scanning 3 months postablation appears to be an effective and reliable screening tool that can be used to identify asymptomatic patients with significant stenosis. The best clinical management for asymptomatic patients with severe stenosis is poorly defined. We typically refer these patients for pulmonary vein intervention; however, the patient's age, comorbidities, functional capacity, as well as the size of the pulmonary vein affected, all need to be carefully considered with the patient before proceeding.

Impact of Patent Foramen Ovale on Left Atrial Linear Lesions in the Context of Atrial Fibrillation Ablation

We investigated the impact of the mode of left atrial (LA) access via patent foramen ovale (PFO) versus transseptal (TS) puncture on LA linear lesions during atrial fibrillation (AF) ablation. We investigated 139 (PFO: 25) consecutive patients who underwent mitral isthmus (MI) and/or LA roof linear ablation. Technical endpoint was completeness of linear lesions and duration of radiofrequency (RF) application. During the initial procedure, complete MI and LA roof blocks were created in 13 of 19 (68%) and 14 of 17 (82%) patients in the PFO group, and in 57 of 94 (61%) and 54 of 70 (74%) patients in the TS group, respectively (P = NS). There was no significant difference in RF durations at MI (11.1 ± 8.9 and 15.1 ± 7.6 minutes, P = 0.11), and LA roof (10.1 ± 3.5 and 8.3 ± 5.0 minutes, P = 0.21) between the 2 groups. Among 28 patients who underwent repeat linear ablation, complete MI and LA roof blocks were created in 3 of 4 (75%) and 0 of 1 (0%) patients in the PFO group, and in 16 of 21 (76%) and 7 of 10 (70%) patients in the TS group, respectively (P = NS). There was no significant difference in RF durations at MI (15.3 ± 8.3 and 19.5 ± 18.3 minutes, P = 0.71), and LA roof (19.0 and 10.3 ± 5.4 minutes, P = 0.19) between the 2 groups. Clinical outcomes at 12 months were also similar. There were no significant differences in the procedural success rates, durations of RF application, 12-month clinical outcomes, and complication rates of LA linear ablation between the PFO and TS groups. Accessing the LA via a PFO is not an unfavorable approach toward LA linear ablation.

Brugada Syndrome Caused by a Large Deletion in SCN5A Only Detected by Multiplex Ligation-Dependent Probe Amplification

A 14-year-old boy presented with atrial flutter. His ECG showed Brugada changes, first-degree AV block and major sinus pauses. Polymorphic VT was inducible at electrophysiology study. A pacemaker defibrillator was placed. Classic sequencing for SCN5A was normal. Multiplex ligation-dependent probe amplification, however, detected a major deletion in SCN5A. It is predicted that this deletion would result in haploinsufficiency. The report is the first description of a large-scale rearrangement of the SCN5A gene and supports the association between the molecular pathology and the phenotypic expression.

Histogram Analysis: A Novel Method to Detect and Differentiate Fractionated Electrograms During Atrial Fibrillation

Complex fractionated atrial electrograms (CFAEs) might identify the critical substrate maintaining AF. We developed a method based upon histogram analysis of interpeak intervals (IPIs) to automatically quantify fractionation and differentiate between subtypes of CFAEs. Two experts classified 1,681 fibrillatory electrograms recorded in 13 patients with persistent AF into 3 categories (gold standard): normal electrograms, discontinuous CFAEs, or continuous CFAEs. Histogram analysis of IPI was performed to calculate the P5, P50, P95, and the mean of IPIs, in addition to the total number of IPI (N(Total)), and the number of IPI within predetermined ranges: 10-60 (N(Short)), 60-120 (N(Intermediate)), and >120 ms (N(Long)). P50 and N(Long) were higher in the normal electrograms compared to the other 2 categories (P < 0.001). N(Intermediate) was higher in the discontinuous CFAE category compared to the other 2 categories. P95, mean IPI, N(Total), and N(Short) were all significantly different among the 3 categories (P < 0.001) and correlated with the degree of fractionation (r =-0.52, -0.55, 0.68, and 0.67, respectively). Receiver operating characteristic (ROC) curves showed good diagnostic accuracy (area under curve, AUC > 0.8) of P50 and N(Long) to detect normal electrograms. An algorithm using N(Intermediate) showed good diagnostic accuracy (AUC > 0.7) to detect discontinuous CFAEs, whereas P95, mean, N(Total), and N(Short) all revealed high diagnostic accuracy (AUC > 0.85) to detect continuous CFAEs. This was confirmed in a prospective data set. Histogram analysis of IPI can differentiate between normal electrograms, discontinuous and continuous fractionated electrograms. This method might be used to standardize and optimize ablation strategies in AF.

Effects of Dronedarone on Clinical Outcomes in Patients with Lone Atrial Fibrillation: Pooled Post Hoc Analysis from the ATHENA/EURIDIS/ADONIS Studies

Dronedarone has been shown to reduce cardiovascular hospitalizations or death in patients with atrial fibrillation (AF) and additional risk factors. This post hoc exploratory analysis examines its effects in the subgroup of lone AF patients. Individual data from patients with lone AF enrolled in the EURIDIS, ADONIS, and ATHENA trials were entered in a central database. The effects of dronedarone compared to placebo on the composite endpoint of cardiovascular hospitalizations or death, and their individual components, were evaluated. A total of 432 (192 placebo and 240 dronedarone) patients (7% of the total population) were classified as having lone AF (69.4% male patients, mean age 64 ± 13 years). The patients were followed for 13.8 ± 7.2 months. The risk for first cardiovascular hospitalizations or death from any cause in the placebo group after 1 year was 25% in the lone AF group compared to 29% the rest of the population. For patients with lone AF, dronedarone led to a 44% reduction of cardiovascular hospitalizations or death (hazard ratio (HR) 0.56; 95%CI 0.36-0.88, P = 0.004) and to a 46% reduction in cardiovascular hospitalizations alone (HR 0.54; 95%CI 0.34-0.87, P = 0.004) compared to placebo. HR for all-cause mortality was 1.02 (95%CI 0.31-3.34, P = 0.885). All findings were homogeneous across the 3 studies and similar to those observed in the overall population. According to this post hoc analysis, patients with lone AF have a high risk for cardiovascular hospitalization within 1 year. Dronedarone when added to standard of care reduces the risk of cardiovascular hospitalizations in this population.

Journal of Cardiovascular Electrophysiology-2010

Journal of Cardiovascular ElectrophysiologyVolume 22, Issue 2 p. 119-119 Journal of Cardiovascular Electrophysiology—2010 Eric N. Prystowsky M.D., Search for more papers by this author Eric N. Prystowsky M.D., Search for more papers by this author First published: 11 February 2011 https://doi.org/10.1111/j.1540-8167.2010.02024.x J Cardiovasc Electrophysiol, Vol. 22, p. 119, February 2011. Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume22, Issue2February 2011Pages 119-119 RelatedInformation

Effects of Chronic Amiodarone on the Electrical Restitution in the Human Ventricle With Reference to Its Antiarrhythmic Efficacy

Dynamic instability of ventricular refractoriness represented by electrical restitution operates synergistically with tissue heterogeneity to increase the propensity for functional reentry leading to ventricular tachycardia/fibrillation (VT/VF). Little is known about the effect of chronic amiodarone on the electrical restitution in the human ventricle. Restitution kinetics of monophasic action potential duration (MAPD(90)) in the right ventricular outflow tract (RVOT) and apex (RVA), and of inverse of conduction time from RVOT to RVA (CT(-1)), were estimated by an S1-S2 protocol in 22 patients treated with amiodarone (180 ± 33 mg/day for 7 ± 9 months) and in 30 without treatment. In the untreated patients, the restitution kinetics of CT(-1) was steeper in the group with structural heart disease (SHD) (UNT(SHD+), n = 18) than without SHD (UNT(SHD-), n = 12), whereas MAPD(90) restitution parameters were comparable. In the amiodarone-treated patients (all with SHD), the shortest diastolic interval to produce a ventricular response (DI(min)) was increased, the maximum slope of MAPD(90) was flattened, and the magnitude of CT(-1) restitution was reduced as compared with UNT(SHD+). Sustained VT/VF was induced in 7 of 18 UNT(SHD+) (38.9%) and in 4 of 22 amiodarone-treated patients (18.2%, P = 0.07). Concomitant presence of increased CT(-1) restitution and dispersion of MAPD(90) restitution was required for the VT/VF induction. The suppression of VT/VF in the amiodarone-treated patients was associated with a smaller magnitude of CT(-1) restitution in the presence of limited dispersion of MAPD(90) restitution. Chronic amiodarone flattens restitution kinetics of MAPD(90) and CT(-1) in the human ventricle, which could be antiarrhythmic in patients with limited tissue heterogeneity.

Three Origins of Focal Atrial Tachycardia in the Lateral Mitral Isthmus

Multiple origins of focal atrial tachycardia (AT) located at the left lateral isthmus is a rare case. We present a case of a 31-year-old female with incessant AT. During radiofrequency ablation, 3 origins of AT located in the lateral mitral ishtmus from a lower to a higher position were identified with changes of the ECG morphology and earliest activation on 3D mapping. Ablation of the AT origins can terminate the tachycardia.

Intrinsic Cardiac Autonomic Stimulation Induces Pulmonary Vein Ectopy and Triggers Atrial Fibrillation in Humans

The induction of atrial fibrillation (AF) by pulmonary vein (PV) ectopy is well described. The triggers for these PV ectopy are not so well understood. The intrinsic cardiac autonomic nervous system (ANS) has been suggested as a potential upstream regulator that may cause PV ectopy and atrial fibrillation (AF). We hypothesized that activation of the ANS by high frequency stimulation (HFS) of atrial ganglionated plexi (GP) can initiate PV ectopy. During sinus rhythm in 12 patients undergoing ablation for paroxysmal AF, short bursts of HFS, synchronized to the local atrial refractory period, were delivered at presumed GP sites. Electrograms were recorded from catheters placed in the PV, coronary sinus (CS) and high right atrium (HRA). A total of 112 episodes of HFS were recorded, producing ectopic activity in 91 of 112 (81%) episodes. Of these 91 episodes, there were 46 episodes of isolated single ectopic beats, 5 episodes of double ectopic responses, 24 episodes of ectopy/tachycardia lasting <30 s, and 16 episodes of AF lasting >30 s. In 63 of 91 episodes, the PV catheter was placed adjacent to the stimulated GP, resulting in ectopy recorded earliest in the PV catheter in 48 of 63 (76%) episodes. In one patient, reproducible ectopy was shown to occur following AV nodal conduction delay in response to HFS. Without HFS, neither AV nodal conduction delay nor ectopy occurred. This study has demonstrated a direct link between activation of the intrinsic cardiac autonomic nervous system and pulmonary vein ectopy in humans.

Differentiating Macroreentrant from Focal Atrial Tachycardias Occurred After Circumferential Pulmonary Vein Isolation

Atrial tachycardias (ATs) are commonly observed following catheter ablation of atrial fibrillation (AF). The aim of this study was to identify ECG characteristics that differentiate focal from macroreentrant ATs after circumferential pulmonary vein isolation (CPVI). One hundred and twenty ATs that occurred after CPVI were mapped using a 3-dimensional mapping system in 87 patients with AF. Further ablation was performed to eliminate the ATs. The surface ECGs of 68 ATs in 41 consecutive patients (Group 1) were analyzed retrospectively to create diagnostic algorithms. The algorithms were tested in the second 46 consecutive patients (Group 2). Patients with macroreentrant AT had lower left atrial (LA) voltage than those with focal AT (1.3 ± 0.3 vs 1.5 ± 0.2 mV, P = 0.01). Focal AT had a higher incidence of a positive polarity in V6 compared with macroreentrant AT (88% vs 55%, P = 0.03). The positive amplitude of the flutter/P waves in V6 was higher for focal AT than macroreentrant AT. The cycle lengths of the focal ATs were longer than those for macroreentrant AT (296 ± 107 vs 244 ± 25 ms, P < 0.001). Right atrial macroreentrant AT had a higher incidence of a negative polarity in at least 1 precordial lead compared with LA macroreentry. The positive flutter waves in V1 could differentiate roof/mitral isthmus dependent from non-roof/mitral isthmus dependent macroreentry. This algorithm correctly differentiated the focal from macroreentrant ATs with a sensitivity of 94%, specificity of 91%, and predictive accuracy of 92% in Group 2. Different electrophysiological properties may facilitate the differentiation between macroreentrant and focal ATs after CPVI.

Change in Coronary Sinus Activation Following Catheter Ablation: What Is the Mechanism?

Journal of Cardiovascular ElectrophysiologyVolume 22, Issue 6 p. 720-722 Arrhythmia Rounds† Change in Coronary Sinus Activation Following Catheter Ablation: What Is the Mechanism? PUGAZHENDHI VIJAYARAMAN M.D., PUGAZHENDHI VIJAYARAMAN M.D. Cardiac Electrophysiology, Geisinger Wyoming Valley Medical Center, Wilkes-Barre, Pennsylvania, USASearch for more papers by this authorMARK A. WOOD M.D., MARK A. WOOD M.D. Division of Cardiac Electrophysiology, Virginia Commonwealth University Health System, Richmond, Virginia, USASearch for more papers by this authorRICHARD K. SHEPARD M.D., RICHARD K. SHEPARD M.D. Division of Cardiac Electrophysiology, Virginia Commonwealth University Health System, Richmond, Virginia, USASearch for more papers by this authorKENNETH A. ELLENBOGEN M.D., KENNETH A. ELLENBOGEN M.D. Division of Cardiac Electrophysiology, Virginia Commonwealth University Health System, Richmond, Virginia, USASearch for more papers by this author PUGAZHENDHI VIJAYARAMAN M.D., PUGAZHENDHI VIJAYARAMAN M.D. Cardiac Electrophysiology, Geisinger Wyoming Valley Medical Center, Wilkes-Barre, Pennsylvania, USASearch for more papers by this authorMARK A. WOOD M.D., MARK A. WOOD M.D. Division of Cardiac Electrophysiology, Virginia Commonwealth University Health System, Richmond, Virginia, USASearch for more papers by this authorRICHARD K. SHEPARD M.D., RICHARD K. SHEPARD M.D. Division of Cardiac Electrophysiology, Virginia Commonwealth University Health System, Richmond, Virginia, USASearch for more papers by this authorKENNETH A. ELLENBOGEN M.D., KENNETH A. ELLENBOGEN M.D. Division of Cardiac Electrophysiology, Virginia Commonwealth University Health System, Richmond, Virginia, USASearch for more papers by this author First published: 14 January 2011 https://doi.org/10.1111/j.1540-8167.2010.01988.xCitations: 3 Address for correspondence: Pugazhendhi Vijayaraman, M.D., Director, Cardiac Electrophysiology, Geisinger Wyoming Valley Medical Center, MC 36-10, 1000 E. Mountain Boulevard, Wilkes-Barre, PA 18702, USA. Fax: 570-821-2306; E-mail: pvijayaraman1@geisinger.edu, pvijayaraman@gmail.com J Cardiovasc Electrophysiol, Vol. 22, pp. 720-722, June 2011. No disclosures. Section Editor: George J. Klein, M.D. Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume22, Issue6June 2011Pages 720-722 RelatedInformation

99mTc-MAA lung scan can be an alternative in detection and follow-up of patent foramen ovale

[1] Rassi Jr A, Rassi A. Predicting prognosis in patients with Chagas disease: why are the results of various studies so different? Int J Cardiol 2010;145:64–5. [2] HlatkyMA, Greenland P, Arnett DK, et al. Criteria for evaluation of novel markers of cardiovascular risk: a scientific statement from the American Heart Association. Circulation 2009;119:2408–16. [3] Nagueh SF, Middleton KJ, Kopelen HA, Zoghbi WA, Quinones MA. Doppler tissue imaging: a noninvasive technique for evaluation of left ventricular relaxation and estimation of filling pressures. J Am Coll Cardiol 1997;30:1527–33. [4] Nunes MC, Barbosa MM, Ribeiro AL, Colosimo EA, Rocha MO. Left atrial volume provides independent prognostic value in patients with chagas cardiomyopathy. J Am Soc Echocardiogr 2009;22:82–8. [5] Lang RM, Bierig M, Devereux RB, et al. Recommendations for chamber quantification: a report from the American Society of Echocardiography's guidelines and Standards committee and the chamber quantification writing group, developed in conjunction with the European Association of Echocardiography, a Branch of the European Society of Cardiology. J Am Soc Echocardiogr 2005;18:1440–63. [6] Steyerberg EW. Clinical predictions models. A practical approach to development, validation, and updating. New York: Springer; 2009. [7] Janes H, Pepe MS, Gu W. Assessing the value of risk predictions by using risk stratification tables. Ann Intern Med 2008;149:751–60. [8] Pencina MJ, D'Agostino Sr RB, D'Agostino Jr RB, Vasan RS. Evaluating the added predictive ability of a new marker: from area under the ROC curve to reclassification and beyond. Stat Med 2008;27:157–72. [9] Rassi Jr A, Rassi A, Little WC, et al. Development and validation of a risk score for predicting death in Chagas' heart disease. N Engl J Med 2006;355:799–808. [10] R Development Core Team. R: a language and environment for statistical computing. Vienna, Austria: R Foundation for Statistical Computing3-90005107-0; 2009. URLhttp://www.R-project.org. [11] Ribeiro AL, Cavalvanti PS, Lombardi F, Nunes Mdo C, Barros MV, Rocha MO. Prognostic value of signal-averaged electrocardiogram in Chagas disease. J Cardiovasc Electrophysiol 2008;19:502–9. [12] Shewan LG and Coats AJ. Ethics in the authorship and publishing of scientific articles Int J Cardiol 2010;144:1–2.

Effects of Autonomic Interventions on Atrial Restitution Properties

Atrial Restitution Properties. The restitution hypothesis suggests that action potential duration (APD) restitution slope >1 predicts the development of alternans and fibrillation. This study aimed to investigate the effects of autonomic interventions on the restitution properties on the atria. In 10 anesthetized open-chest dogs, multiple electrode catheters were sutured at pulmonary vein and atrial sites. The monophasic APD was recorded by an Ag-AgCl catheter. The restitution curve at each site was constructed by plotting each APD(90) against the preceding diastolic interval at incremental atrial pacing rates before and after vagal nerve stimulation (VNS) or ganglionated plexi (GP) ablation. Before GP ablation, VNS significantly shortened the APD, flattened the restitution curves and suppressed the APD alternans at each site, while increasing the atrial fibrillation (AF) inducibility and duration (P < 0.05 for all). These effects were eliminated by GP ablation. Compared with the baseline, GP ablation significantly increased the APD, steepened the restitution curves, and facilitated the APD alternans at each site while decreasing the AF inducibility and duration (P < 0.05 for all). VNS significantly increased (0.5 ± 0.2 vs 0.3 ± 0.1, P < 0.05) and GP ablation decreased (0.2 ± 0.1 vs 0.3 ± 0.1, P < 0.05) the spatial dispersion of the slopes of APDR curves, respectively. The maximal slope of APDR curve alone does not fully account for the changes of AF inducibility and duration induced by autonomic interventions; instead, the spatial dispersion of the APDR kinetics may be an important determinant for susceptibility of AF.

Ablation of Atrial Fibrillation at the Time of Cavotricuspid Isthmus Ablation in Patients With Atrial Flutter Without Documented Atrial Fibrillation Derives a Better Long-Term Benefit

AF Ablation in Patients With Only Documentation of Atrial Flutter. The aim of the study was to evaluate whether isolation of the pulmonary veins (PVs) at the time of cavotricuspid isthmus (CTI) ablation is beneficial in patients with lone atrial flutter (AFL). A high proportion of patients with lone persistent AFL have recurrent episodes of atrial fibrillation (AF) after CTI ablation. However, the benefit of AF ablation in patients with only documentation of AFL has not been determined. Forty-eight patients with typical lone persistent AFL (age 56 ± 6; 90% male) were randomized to CTI ablation (Group A; n = 25) or to CTI + PV isolation (PVI) (Group B; n = 23). In addition to PVI, some patients in group B underwent ablation of complex fractionated electrograms and/or creation of left atrial roof and mitral isthmus ablation line in a stepwise approach when AF was induced and sustained for more than 2 minutes. Mean follow-up was 16 ± 4 months with a 48-hour ambulatory monitor every 2 months. There were no recurrences of AFL in either group. Six patients in group B (22%) underwent a stepwise ablation protocol. AF organized and terminated in 5 patients during ablation (83%). Complication rate was not significantly different among the groups. Twenty patients in group B (87%) and 11 patients in group A (44%) were free of arrhythmias on no medications at the end of follow-up (P < 0.05). Ablation of AF at the time of CTI ablation results in a significantly better long-term freedom from arrhythmias.

Percutaneous Epicardial Left Atrial Appendage Closure: Intermediate-Term Results

Chronic Percutaneous Epicardial Appendage Closure. To assess the chronic safety and feasibility of percutaneous epicardial closure of the left atrial appendage (LAA) guided by electrical navigation. Atrial fibrillation (AF) is associated with stroke, and LAA occlusion may be a useful nonpharmacologic strategy for stroke prevention in AF. Percutaneous epicardial access was obtained in 6 dogs under general anesthesia. The ligation system included a grabber that captures the LAA guided by local electrograms (EGMs) and a looped hollow suture preloaded with a central wire enabling control and visualization. After a satisfactory position is confirmed the loop is tightened remotely, and the suture cut. Transesophageal echocardiography (TEE) assessed LAA dimensions and flow. LAA EGMs were recorded pre- and postclosure, and neurohormonal markers measured. Pathologic examination was performed. LAA ligation was successful in all dogs. LAA flow was immediately abolished in 5 of 6 dogs. Disappearance of local LAA EGMs following ligation was observed in all animals. Follow-up TEE at mean 54 days (range 23-75 days) documented residual flow in only the first 2 dogs. Prior to necropsy the LAA was examined at thoracotomy in 3 animals. Following a minor design change, complete closure and fibrosis with a remnant atretic LAA was noted in all animals. No damage to adjacent structures was noted. Neurohormonal markers were unchanged. Percutaneous epicardial LAA ligation guided by electrical navigation is feasible with promising intermediate-term results in the canine model. The technique may be useful as an alternative to existing methods of LAA obliteration in humans.