David O'donnell

Clinical and electrophysiological differences between patients with arrhythmogenic right ventricular dysplasia and right ventricular outflow tract tachycardia

AIMS Radiofrequency catheter ablation is considered first line treatment for symptomatic patients with right ventricular outflow tract tachycardia (RVOT). The role of ablation in arrhythmogenic right ventricular dysplasia (ARVD) is more limited. As such, differentiating between the two conditions is essential. METHODS AND RESULTS This study compared non-invasive findings, magnetic resonance images (MRI), invasive electrophysiological characteristics, results of ablation and long-term outcome in 50 consecutive patients with RVOT (33) or ARVD (17). Structural abnormalities were uniform in the ARVD group; in addition 18 (54%) of the RVOT tachycardia group had MRI abnormalities. At electrophysiological study the tachycardia in the ARVD group displayed features of re-entry in over 80%, but behaved with a triggered automatic basis in 97% with RVOT. Ablation was complete or partial success in 12 (71%) patients with ARVD and ventricular tachycardia (VT) recurred in eight (48%). In the RVOT patients, ablation was a complete success in 97% with recurrent VT in 6%. Long-term success in the RVOT patients was 95% in both patients with and without MRI abnormalities. CONCLUSIONS Electrophysiological characterization can differentiate ARVD from RVOT. The finding of abnormalities on MRI does not have any bearing on arrhythmia mechanism, acute or long-term success of RFA.

Paroxysmal cycle length shortening in the pulmonary veins during atrial fibrillation correlates with arrhythmogenic triggering foci in sinus rhythm.

Identifying Arrhythmogenic PVs in AF. Introduction: The focal origin of atrial fibrillation (AF) is identified by recording atrial ectopic beats or the ectopic activity that precedes AF. We hypothesized that arrhythmogenic pulmonary veins (PVs) also could be identified during persistent AF.

Pulmonary vein ablation for idiopathic atrial fibrillation: six month outcome of first procedure in 100 consecutive patients

Objectives: To report six month outcome in patients undergoing their first pulmonary vein ablation procedure for idiopathic atrial fibrillation (AF) at a “non-pioneering” hospital. Design: Prospective observational study. Setting: Specialist electrophysiology unit at a university hospital. Patients: The first 100 consecutive patients undergoing their first pulmonary vein catheter ablation procedure for highly symptomatic, drug resistant AF in the period 1999–2002. Main outcome measures: Incidence of symptomatic or asymptomatic, Holter documented AF six months after ablation. Results: Mean patient age was 52 years (range 23–73 years), mean length of AF history 53 months (range 6–180 months), mean number of antiarrhythmic drug failures was 3 (range 1–5), and 81 were men. At the time of the ablation procedure, 64 had progressed to persistent AF and 23 had increased transverse left atrial diameter. The number of pulmonary veins ablated in each patient was one in 11, two in 45, three in 36, and four in 8. Six months after ablation, 55 patients were consistently in sinus rhythm, asymptomatic, and without any Holter evidence of AF. The chance of being in sinus rhythm was 73% (29 of 64) in those with paroxysmal as compared with only 45% (26 of 36) in those with persistent AF at the time of ablation (p  =  0.01). Outcome was not influenced by patient age, length of AF history, or duration of persistent AF before ablation or to left atrial dimension. Follow up was complete and no patient has died or experienced a stroke during or after ablation; nor have any developed symptoms of late pulmonary vein stenosis. However, other complications occurred during or shortly after the procedure in 12 patients, including cardiac tamponade in six. Conclusions: In selected patients with drug resistant AF, focal pulmonary vein catheter ablation offers a realistic prospect of achieving stable sinus rhythm compared with alternatives. However, it is a complex form of ablation with a significant risk of serious complications. Although a new milestone in arrhythmia management, the optimum ablation technique is still evolving and any impact on the natural history of AF remains to be determined.

Interatrial Transseptal Electrical Conduction: Comparison of Patients with Atrial Fibrillation and Normal Controls

Interatrial Electrical Conduction. Introduction: This study analyzed the electrophysiologic properties of interatrial transseptal electrical conduction at Bachmanns bundle and the ostium of the coronary sinus (CS os) in response to pulmonary vein (PV) stimuli, which mimicked spontaneous ectopy.

Dynamic alterations in right atrial activation during atrial fibrillation.

Atrial fibrillation (AF) is usually considered to be a disorganized rhythm. However, several reports have described areas of organized right atrial (RA) activation during AF. We describe a patient with focal paroxysmal AF with a consistent pattern of organized RA activity despite typically disorganized left atrial activity. The sequence of RA activation varied, depending on which pulmonary vein foci initiated the AF.

COMPUTER ASSISTED CHARACTERIZATION OF RAPID REPETITIVE ELECTRICAL ACTIVATIONS IN THE PULMONARY VEINS DURING ATRIAL FIBRILLATION

Our group has described previously the identification of arrhythmogenic pulmonary veins by rapid local electrical activations during atrial fibrillation. We have now investigated an algorithm for automated computer detection of this phenomenon from catheter electrodes in the upper pulmonary veins and assessed its performance in identifying arrhymogenic veins. Ten patients with persistent atrial fibrillation scheduled for pulmonary vein isolation at this hospital were studied. Electrogram recordings in the upper pulmonary veins were recorded and analyzed. Arrhythmogenic veins were identified by focal activity during sinus rhythm at electrophysiological studies. Recordings were visually assessed by a cardiologist for the presence of rapid repetitive electrical activations during atrial fibrillation. An index of rapid repetitive electrical activity (RREA index), the ratio of the number of activations with cycle lengths in the range 50 ms to 100 ms to the number of activations with cycle lengths in the range 100 ms to 200 ms, was devised to describe the extent of such activity automatically. The index was assessed as a predictor of arrhythmogenic veins. Electrograms from 19 upper pulmonary veins were recorded. Rapid activity was evident in 15 veins by visual manual assessment. The mean (range) automatic RREA index was 0.07 (0 to 0.16) for those identified as having no such activity manually, and 0.83 (0.22 to 1.68) for those identified with rapid activity (p<0.0001). With a threshold of RREA index in the range 0.17 to 0.21, the identification of veins with rapid firing was exactly the same as for manual assessment. Eleven upper pulmonary veins were identified as arrhythmogenic during electrophysiological study, and the identification of these veins by both manual and automatic assessment of rapid repetitive electrical activations gave a sensitivity of 100% (11/11) and specificity of 50% (4/8). A technique for automatic characterization of electrogram cycle length has been demonstrated and could be used online as a tool for identifying candidate sites for pulmonary vein isolation in patients despite persistent atrial fibrillation.

Challenges and limitations in the diagnosis of atrioesophageal fistula: HA et al.

Atrioesophageal fistula (AEF) is a dire complication of atrial fibrillation ablation. The diagnostic yield of computed tomography (CT) chest, the role and timing of repeat testing, and the value of other investigations in the diagnosis of AEF is uncertain.