A simplified differential pacing technique for the evaluation of bidirectional cavo-tricuspid isthmus block during ablation of typical atrial flutter.

PURPOSE: Bidirectional block of the cavo-tricuspid isthmus (CTI) is an established endpoint of CTI-dependent atrial flutter (AFl) ablation. Differential pacing has been used to evaluate the CTI block. The purpose of this study is to describe a modified differential pacing technique to evaluate the CTI block. METHODS: Sixty-two patients underwent radiofrequency (RF) ablation of CTI-dependent AFl. The acute endpoints were non-inducibility of the AFl, and verification of the bidirectional CTI block by our methodology. Pacing was performed in the CS with an ablation catheter positioned immediately lateral to the CTI ablation line, and then 1-2 cm more laterally. The stimulus-to-ablation catheter atrial electrogram intervals were measured at these sites (StimCS-Abl1 and StimCS-Abl2, respectively). Pacing with the ablation catheter also was performed at these 2 sites, and the stimulus-to-CS electrogram intervals (StimABL1-CS and StimABL2-CS) were measured. The criteria for the bidirectional block were StimCS-Abl1 > StimCS-Abl2, and StimABL1-CS > StimABL2-CS. Clinical efficacy was defined as freedom from recurrent AFl during follow-up. RESULTS: Following 12.2 ± 3.7 min of RF delivery across the CTI, intervals were StimCS-Abl1 = 181.2 ± 22.7 ms and StimABL1-CS = 181.0 ± 23.6 ms, and StimCS-Abl2 = 152.2 ± 26.5 ms and StimABL2-CS = 151.2 ± 22.7 (P < 0.001). Atrial flutter was rendered not inducible in all patients, and no procedural complications were encountered. During the next 15.9 ± 0.7 months, two patients were lost to follow-up, and among the 62 other patients, one (1.7%) had flutter recurrence. CONCLUSIONS: The bidirectional CTI block can be assessed quickly and easily using only the ablation and CS catheters for differential pacing.

Low-Level Tragus Stimulation Modulates Atrial Alternans and Fibrillation Burden in Patients With Paroxysmal Atrial Fibrillation.

Background Low-level tragus stimulation (LLTS) has been shown to significantly reduce atrial fibrillation (AF) burden in patients with paroxysmal AF. P-wave alternans (PWA) is believed to be generated by the same substrate responsible for AF. Hence, PWA may serve as a marker in guiding LLTS therapy. We investigated the utility of PWA in guiding LLTS therapy in patients with AF. Methods and Results Twenty-eight patients with AF were randomized to either active LLTS or sham (earlobe stimulation). LLTS was delivered through a transcutaneous electrical nerve stimulation device (pulse width 200 µs, frequency 20 Hz, amplitude 10-50 mA), for 1 hour daily over a 6-month period. AF burden over 2-week periods was assessed by noninvasive continuous ECG monitoring at baseline, 3 months, and 6 months. A 5-minute control ECG for PWA analysis was recorded during all 3 follow-up visits. Following the control ECG, an additional 5-minute ECG was recorded during active LLTS in all patients. At baseline, acute LLTS led to a significant rise in PWA burden. However, active patients receiving chronic LLTS demonstrated a significant reduction in both PWA and AF burden after 6 months (P<0.05). Active patients who demonstrated an increase in PWA burden with acute LLTS showed a significant drop in AF burden after 6 months of chronic LLTS. Conclusions Chronic, intermittent LLTS resulted in lower PWA and AF burden than did sham control stimulation. Our results support the use of PWA as a potential marker for guiding LLTS treatment of paroxysmal AF.

Electrophysiology testing for risk stratification of patients with ischaemic cardiomyopathy: a call for action.

Current guidelines recommendations, based on the results of primary sudden cardiac death prevention trials, use the left ventricular ejection fraction (LVEF) as a sole criterion for the indication of implantable cardioverter defibrillator therapy for primary prevention purposes. In this article, we review the sensitivity and specificity of LVEF for predicting arrhythmic vs. non-arrhythmic cardiac death and examine existing evidence on the use of electrophysiology testing for risk stratification of ischaemic patients with reduced left ventricular function.

Coexistent Types of Atrioventricular Nodal Re-Entrant Tachycardia: Implications for the Tachycardia Circuit.

BACKGROUND: There is evidence that atypical fast-slow and typical atrioventricular nodal re-entrant tachycardia (AVNRT) do not use the same limb for fast conduction, but no data exist on patients who have presented with both typical and atypical forms of this tachycardia. We compared conduction intervals during typical and atypical AVNRT that occurred in the same patient. METHODS AND RESULTS: In 20 of 1299 patients with AVNRT, both typical and atypical AVNRT were induced at electrophysiology study by pacing maneuvers and autonomic stimulation or occurred spontaneously. The mean age of the patients was 47.6±10.9 years (range, 32-75 years), and 11 patients (55%) were women. Tachycardia cycle lengths were 368.0±43.1 and 365.8±41.1 ms, and earliest retrograde activation was recorded at the coronary sinus ostium in 60% and 65% of patients with typical and atypical AVNRT, respectively. Thirteen patients (65%) displayed atypical AVNRT with fast-slow characteristics. By comparing conduction intervals during slow-fast and fast-slow AVNRT in the same patient, fast pathway conduction times during the 2 types of AVNRT were calculated. The mean difference between retrograde fast pathway conduction during slow-fast AVNRT and anterograde fast pathway conduction during fast-slow AVNRT was 41.8±39.7 ms and was significantly different when compared with the estimated between-measurement error (P=0.0055). CONCLUSIONS: Our data provide further evidence that typical slow-fast and atypical fast-slow AVNRT use different anatomic pathways for fast conduction.

Differential diagnosis of regular, narrow-QRS tachycardias.

We present an update on clinical and electrophysiological criteria used for the differential diagnosis of regular supraventricular tachycardias. Although several electrocardiographic clues may assist in the differential diagnosis, this is usually accomplished at electrophysiology study, and most often, the differential diagnosis is between atrioventricular nodal reentrant tachycardia, atrioventricular reentrant tachycardia due to a concealed accessory pathway, and atrial tachycardia. Atrial and ventricular pacing maneuvers during sinus rhythm or tachycardia have been used with various success rates. In clinical practice, these techniques cannot be applied to all cases, and multiple criteria must be used for the differential diagnosis of narrow-complex tachycardias with atypical characteristics.

Autonomic denervation added to pulmonary vein isolation for paroxysmal atrial fibrillation: a randomized clinical trial.

OBJECTIVES: The aim of this study was to investigate whether the combination of conventional pulmonary vein isolation (PVI) by circumferential antral ablation with ganglionated plexi (GP) modification in a single ablation procedure, yields higher success rates than PVI or GP ablation alone, in patients with paroxysmal atrial fibrillation (PAF). BACKGROUND: Conventional PVI transects the major left atrial GP, and it is possible that autonomic denervation by inadvertent GP ablation plays a central role in the efficacy of PVI. METHODS: A total of 242 patients with symptomatic PAF were recruited and randomized as follows: 1) circumferential PVI (n = 78); 2) anatomic ablation of the main left atrial GP (n = 82); or 3) circumferential PVI followed by anatomic ablation of the main left atrial GP (n = 82). The primary endpoint was freedom from atrial fibrillation (AF) or other sustained atrial tachycardia (AT), verified by monthly visits, ambulatory electrocardiographic monitoring, and implantable loop recorders, during a 2-year follow-up period. RESULTS: Freedom from AF or AT was achieved in 44 (56%), 39 (48%), and 61 (74%) patients in the PVI, GP, and PVI+GP groups, respectively (p = 0.004 by log-rank test). PVI+GP ablation strategy compared with PVI alone yielded a hazard ratio of 0.53 (95% confidence interval: 0.31 to 0.91; p = 0.022) for recurrence of AF or AT. Fluoroscopy duration was 16 ± 3 min, 20 ± 5 min, and 23 ± 5 min for PVI, GP, and PVI+GP groups, respectively (p < 0.001). Post-ablation atrial flutter did not differ between groups: 5.1% in PVI, 4.9% in GP, and 6.1% in PVI+GP. No serious adverse procedure-related events were encountered. CONCLUSIONS: Addition of GP ablation to PVI confers a significantly higher success rate compared with either PVI or GP alone in patients with PAF.

Wide-QRS tachycardia inducible by both atrial and ventricular pacing.

We describe an interesting case of an atriofascicular re-entrant tachycardia due to a Mahaim pathway. The differential diagnosis is discussed and a review of the relevant literature is presented.

Cellular replacement therapy for arrhythmia treatment: early clinical experience.

Clinical and experimental studies have demonstrated the proarrhythmic potential of skeletal myoblast transplantation for repair of infarcted myocardium. The evidence on proarrhythmia following bone marrow-derived stem cells, and particular msenchymal stem cells, transplantation is inconclusive. There are experimental and preliminary clinical data supporting the possibility that mesenchymal stem cell transplantation might exert an anti-arrhythmic action by intervening with myocardial scar remodeling. However, clinical experience is limited.

Atrial arrhythmias following ostial or circumferential pulmonary vein ablation.

AIMS: The incidence, clinical significance and optimum treatment of AF ablation-induced proarrhythmia is not entirely known. This report describes the incidence and management of atrial arrhythmias occurring after various techniques for the ablative therapy of atrial fibrillation (AF). METHODS: Five hundred and forty-four patients with paroxysmal atrial fibrillation were subjected to ostial pulmonary vein (PV) (n = 204), antral (n = 300), or circumferential (n = 40) ablation around the PV ostia. RESULTS: Atrial tachycardia or flutter during the first 6 months after AF ablation was detected in 14 patients and was more common among patients subjected to circumferential or circumferential and linear ablation (18% and 22%, respectively) than to other techniques (p < 0.001). The risk of atrial tachycardia or flutter among patients who underwent ostial, ostial with lines and antral ablation was 1%, 8% and 1%, respectively. No difference was observed in the risk of atrial arrhythmia between patients who underwent ablation with or without additional lines, either ostial (p = 0.17) or circumferential (p = 0.99). Re-ablation was performed in patients with sustained atrial arrhythmia (11 out of 14 patients). At 6 months, no recurrence was seen in 10 of these patients as well as in 3 patients with non-sustained atrial tachycardia or flutter. CONCLUSIONS: The incidence of atrial tachycardia or flutter following AF ablation is lower for ostial than circumferential ablation. The addition of lines along the mitral isthmus and between the superior PVs does not significantly affect the risk of ablation-induced arrhythmia. Non-sustained atrial tachycardia or flutter following AF ablation procedures does not always require additional ablation.

Proarrhythmic effects of atrial fibrillation ablation techniques.

BACKGROUND: The incidence of proarrhythmia induced by ablation for atrial fibrillation (AF) is not entirely known. We describe the incidence and management of atrial arrhythmias occurring after various techniques for the ablative therapy of AF. METHODS: Ninety-four patients with paroxysmal AF underwent ostial pulmonary vein (PV) ablation (n=54) or circumferential ablation around the PV ostia (n=40). RESULTS: Atrial tachycardia or flutter was detected during the first 6 months after AF ablation in 10 patients. Atrial arrhythmia was more common among patients who underwent circumferential ablation or circumferential with lines (18.2% and 22.2%, respectively) than in those who were treated with other techniques (p = 0.037). The incidence of atrial tachycardia or flutter among patients who underwent ostial ablation or ostial with lines was 2.4% and 8.3%, respectively. No difference was observed in the risk of atrial arrhythmia between patients who underwent ablation with or without additional lines, either ostial (p = 0.398) or circumferential (p = 0.999). Re-ablation was performed in 7 patients with sustained atrial arrhythmia. At 6 months, no recurrence of atrial tachycardia or flutter was.seen in 6 of these patients, nor in 3 patients with non-sustained atrial tachycardia or flutter. CONCLUSIONS: The incidence of atrial tachycardia or flutter following AF ablation is lower for ostial than for circumferential ablation. The addition of lines along the mitral isthmus and between the superior PVs does not significantly affect the risk of ablation-induced arrhythmia. Non-sustained atrial tachycardia or flutter during or early after AF ablation procedures does not require additional ablation.

Patient and staff radiation dosimetry during cardiac electrophysiology studies and catheter ablation procedures: a comprehensive analysis.

AIMS: To perform a comprehensive analysis of all aspects of patient and in-room personnel radiation dosimetry in interventional electrophysiology. METHODS AND RESULTS: Measurements were performed during 19 diagnostic electrophysiology studies and 24 catheter ablations. Kerma-area product and exposure time values were 48.7 (6.4-230) Gy cm2 and 25.5 (4.4-79.2) min for ablation, and 12.5 (4.5-117.2) Gy cm2 and 4.5 (1.2-31) min for diagnostic studies, respectively. Patient effective doses were 15.2 (2.1-59.6) mSv for ablation and 3.2 (1.3-23.9) mSv for diagnostic procedures. Radiation risk to the patient was estimated to be up to eight cases of fatal cancer in 10,000 procedures. The risk of development of fatal cancer was less than 3x10(-6) per procedure to the primary operator. The risk for the nurse and technician was much lower. The dose per procedure for the primary operator was 7.1 microGy at the eyes, 0.79 microGy at the chest under the lead apron, 13.68 microGy at the chest over the apron, 3.82 microGy at the thyroid, 17.76 microGy at the left hand, and 12.11 microGy at the left knee. CONCLUSION: As far as radiation exposure is concerned, electrophysiology studies followed by radiofrequency ablation are safe procedures for both patient and personnel when performed in catheterization laboratories with modern equipment, experienced operators, and standard safety precautions.

Classification and differential diagnosis of atrioventricular nodal re-entrant tachycardia.

Recent evidence on atrioventricular nodal re-entrant tachycardia has identified several types of this common arrhythmia, with potential therapeutic implications. This article reviews the relevant new information, discusses the differential diagnosis of atrioventricular nodal re-entrant tachycardia, and summarizes the electrophysiological criteria for classification of the various forms of the arrhythmia.

Conduction patterns in the cardiac veins: electrophysiologic characteristics of the connections between left atrial and coronary sinus musculature.

INTRODUCTION: Fractionated electrograms and double potentials have been well described within the coronary sinus (CS) in humans. The pattern of circumferential activation in the CS has not been investigated. Furthermore, no data exist on conduction characteristics within the great cardiac vein (GCV) or the middle cardiac vein (MCV). METHODS AND RESULTS: Twenty patients underwent catheter mapping of the CS, the MCV, and the GCV. Anatomical areas were verified by cannulation of the left superior pulmonary vein. The pattern of circumferential muscle activation within the proximal CS was also studied with a circular mapping catheter (Lasso 12 mm). At conventional mapping during sinus rhythm and high right atrial pacing, discrete double potentials or fractionated electrograms were recorded during left, right atrial and CS pacing at the CS ostium, mid-CS, and distal CS-ligament of Marshall area, in 2 (10%), 1 (5%), and 9 (45%) patients, respectively, whereas no patient displayed such signals in the MCV or GCV ( p < 0.001). Proximal CS mapping with the Lasso was accomplished in 10 patients, 7 of whom had no evidence of multicomponent potentials in the CS at conventional mapping. Specific CS potentials dissociated from the atrial electrograms were recorded in all patiens with the use of circumferential mapping. The perimetric distribution of electrograms within the CS suggested an oblique course of conduction across the CS musculature. CONCLUSION: Potentials representing activation of the CS musculature, with an oblique course of conduction across the CS, can be recorded in human CS but not in the GCV or MCV. This is compatible with anatomical observations of sinus venosus musculature covering the CS but not other cardiac veins, and supports the rationale for the role of CS musculature in the generation of atrial arrhythmias.

Conduction delay within the coronary sinus in humans: implications for atrial arrhythmias.

INTRODUCTION: Striated myocardial connections between the venous wall of the coronary sinus (CS) and the left atrium have been described in humans. This aim of this study was to investigate the conduction properties and potential arrhythmogenicity of CS and left atrial myocardial connections in patients with and patients without paroxysmal atrial fibrillation (PAF). METHODS AND RESULTS: Thirty-eight patients with PAF, 52 patients with other arrhythmias, and 44 patients without arrhythmia underwent catheter mapping of the CS from the distal superoposterior part to the ostium. Catheterization of the superoposterior CS was feasible in 21, 32, and 25 subjects in the three groups, respectively (P = 0.82). Discrete double potentials or fractionated electrograms were recorded during proximal CS or right atrial pacing in 14 (66.7%), 11 (34.4%), and 5 (20.0%) patients, respectively (P = 0.004). In 29 patients, double or fractionated potentials were recorded at the distal superoposterior CS, in 3 at the mid-CS, and in 4 at the ostium. Spontaneous or induced atrial ectopy and/or tachyarrhythmias were recorded in 18 (85.7%), 12 (37.5%), and 2 (8.0%) patients in the three groups, respectively (P < 0.001) and originated from the CS in 6, 3, and 0 patients, respectively (P = 0.010). CONCLUSION: Recording of double potentials is possible within the CS, particularly at its distal superoposterior part, near the left superior pulmonary vein. Their prevalence is higher in patients with PAF than in subjects with other or no arrhythmias, and their presence denotes possible sources or substrate for atrial arrhythmia.