Ablation of right and left atrial premature beats following cardioversion in patients with chronic atrial fibrillation refractory to antiarrhythmic drugs.
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Adult↗
Biomedical subjects
F Leonelli
Publications and source records attributed to F Leonelli.
Prospective randomized comparison of antiarrhythmic therapy versus first-line radiofrequency ablation in patients with atrial flutter.
BACKGROUND: Despite the high success rate of radiofrequency (RF) ablation, pharmacologic therapy is still considered the standard initial therapeutic approach for atrial flutter. OBJECTIVE: We prospectively compared the outcome at follow-up of patients with atrial flutter randomly assigned to drug therapy or RF ablation. METHODS: Patients with at least two episodes of symptomatic atrial flutter in the last four months were randomized to regimens of either antiarrhythmic drug therapy or first-line RF ablation. After institution of therapy, end points included recurrence of atrial flutter, rehospitalization and quality of life. RESULTS: A total of 61 patients entered the study, 30 of whom were randomized to drug therapy and 31 to RF ablation. After a mean follow-up of 21 +/- 11 months, 11 of 30 (36%) patients receiving drugs were in sinus rhythm, versus 25 of 31 (80%) patients who underwent RF ablation (p < 0.01). Of the patients receiving drugs, 63% required one or more rehospitalizations, whereas post-RF ablation, only 22% of patients were rehospitalized (p < 0.01). Following RF ablation, 29% of patients developed atrial fibrillation which was seen in 53% of patients receiving medications (p < 0.05). Sense of well being (pre-RF 2.0 +/- 0.3 vs. post-RF 3.8 +/- 0.5, p < 0.01) and function in daily life (pre-RF 2.3 +/- 0.4 vs. post-RF 3.6 +/- 0.6, p < 0.01) improved after ablation, but did not change significantly in patients treated with drugs. CONCLUSION: In a selected group of patients with atrial flutter, RF ablation could be considered a first-line therapy due to the better success rate and impact on quality of life, the lower occurrence of atrial fibrillation and the lower need for rehospitalization at follow-up.
Aged↗
Catheter ablation approach on the right side only for paroxysmal atrial fibrillation therapy: long-term results.
We report the long-term follow-up of a right side only catheter ablation approach for paroxysmal AF. Eighteen patients with AF refractory to drugs entered the study. Ablation was attempted in the right atrium only by creating linear lesions based on a specific design including from two to four linear lesions. Induction of AF was attempted before ablation and after placement of the lesions. A septal lesion was performed in nine patients. In ten patients atrial defibrillation thresholds (ADFTs) before ablation and following creation of the linear lesions were compared. After a mean follow-up of 22 +/- 11 months, seven patients had recurrence of AF, and another nine patients experienced atrial flutter or atrial tachycardia. Five patients remained in sinus rhythm without medications and four required the use of drugs. Three patients had sporadic AF and six were in chronic AF. The recurrence rate was similar in patients with and without the septal lesion. However, a cure with right side ablation appeared to be predicted by the presence of disorganized and earlier activity in the high right atrium and crista terminalis. Linear lesions in the right atrium were associated with a lower ADFT (pre 2.6 +/- 04 J vs post 1.7 +/- 0.6 J). In conclusion, in a small number of patients, control of AF can be obtained with a right side only approach. Certain activation patterns may identify patients suitable to this approach. No specific lesion pattern appeared more effective. Right atrial linear lesions resulted in lower ADFT.
Atrial Fibrillation↗
Frequency modulation within electrocardiograms during ventricular fibrillation.
Periods of reentrant activation and effective refractory periods are correlated with dominant frequency or reciprocal of cycle periods during ventricular fibrillation (VF). In the present study, we used an analysis technique based on Wigner transforms to quantify time-varying dominant frequencies in electrocardiograms (ECGs) during VF. We estimated dominant frequencies within orthogonal ECGs recorded in 10 dogs during trials of 10 s of VF and in 9 dogs during trials of 30 s of VF. In four additional dogs, we compared dominant frequencies during 10 s of VF before and after administration of amiodarone. Our results showed the following. 1) There was substantial frequency variation or modulation within the ECGs during 10 and 30 s of VF, the average variation being +/-15% from the mean frequency. Amiodarone decreased mean frequencies (P < 0.05) as expected; however, amiodarone also decreased the variation in frequencies (P < 0.05). 2) During 30 s of VF, the dominant frequencies increased continuously from 7.3 to 8.1 Hz (P < 0.05). The increase in frequency was almost linear with a rate of 0.022 Hz/s (r(2) = 0.93, P < 0.0005). 3) Modulation of frequencies during the first and the last one-half of 30 s of VF was not different. Average (in time) mean frequencies and modulation of frequencies were similar in all three ECGs. 4) Although the averages were similar, during any VF episode, dominant frequencies in ECGs recorded from different locations on the body surface were similar to each other at some times and markedly different from each other at other times. We conclude that during VF, 1) frequencies in ECGs vary considerably and continuously, and amiodarone decreases this variation; 2) mean frequencies increase linearly during first 30 s; 3) the variability in frequency does not change during 30 s; and 4) at any given time, the frequencies within spatially different body surface ECGs can be either similar or markedly different.
Amiodarone↗
Usefulness of ibutilide in facilitating successful external cardioversion of refractory atrial fibrillation.
We repeated direct-current cardioversion of atrial fibrillation after ibutilide injection in patients who failed conventional cardioversion. Eleven of 12 patients (92%) had successful cardioversion and avoided the need for internal cardioversion.
Aged↗
AV node ablation and pacemaker implantation after withdrawal of effective rate-control medications for chronic atrial fibrillation: effect on quality of life and exercise performance.
We assess whether AV node ablation and pacemaker implantation after discontinuation of effective rate-control medical therapy for chronic atrial fibrillation had a positive impact on quality of life and exercise performance. To assess the possibility of a placebo effect following pacemaker implantation, the study included three groups of patients. Group 1 underwent an echocardiogram, treadmill exercise, and quality of life measurement 1 month prior to and 6 months following AV node ablation and pacemaker implantation associated with discontinuation of rate-control medications. Group 2 underwent AV node ablation and pacemaker implantation without discontinuation of antiarrhythmic rate-control drugs. Group 3 underwent pacemaker implantation without performing AV node ablation and continuing rate-control medical therapy. At the 1- and 6-month evaluation, the patients in group 1 showed a significant improvement of left ventricular ejection fraction, quality of life, and activity scores. The exercise duration and the maximal VO2 consumption, however, did not change significantly. A slight improvement of the quality of life and physical activity scores was observed in the group undergoing AV node ablation without withdrawal of medications. However, no significant changes were observed in the group receiving only the pacemaker without modification of medical therapy and with intact AV node conduction. In conclusion, in patients with chronic atrial fibrillation, discontinuation of effective rate-control medical therapy followed by AV node ablation and permanent pacing appeared to improve quality of life and activity scores despite no change in exercise duration. The improvement observed does not seem to reflect a placebo effect.
Aged↗
Use of sublingual nitroglycerin during head-up tilt-table testing in patients >60 years of age.
Previous work had demonstrated a reduced specificity associated with head-up tilt protocols using high-dose isoproterenol in patients between 20 and 50 years of age. We evaluated the specificity of head-up tilt testing using different isoproterenol infusion doses and administration of nitroglycerin in patients aged >60 years. In addition, whether the same protocols have impact on the sensitivity of the test was also assessed. One hundred sixty subjects were included in this study. Seventy-six were volunteers randomized to either head-up tilt test with low-dose, 3- and 5-microg/min of isoproterenol (group I) or to a protocol including 0.4 mg of sublingual nitroglycerin (group II). In addition, after an upright tilt drug-free state, 58 patients with a history of syncope underwent repeat head-up tilt with increasing doses of isoproterenol infusion, followed by sublingual nitroglycerin if the test result remained negative. The remaining 33 patients were subjected to the nitroglycerin protocol after the drug-free state phase. In the control groups, the incidence of false-positive responses was 88% and 95%, respectively. In patients with syncope after a negative test result during 5 microg of isoproterenol infusion, nitroglycerin administration increased the number of positive responses from 45% to 79%. The percentage of positive tilt in patients undergoing nitroglycerin administration after the drug-free state part of the protocol was 78%. Administration of nitroglycerin was the most significant predictor of a positive upright tilt in patients with syncope. In subjects aged >60 years, head-up tilt protocols with high-dose isoproterenol infusion and nitroglycerin maintained an adequate specificity. In this subset of patients, nitroglycerin seemed to provide a better sensitivity than isoproterenol.
Administration, Sublingual↗
Ablation of right and left ectopic atrial tachycardias using a three-dimensional nonfluoroscopic mapping system.
We report our experience with mapping and ablation of right and left atrial tachycardia using a 3-dimensional nonfluoroscopic mapping system. Twenty-nine ectopic atrial tachycardias were successfully ablated. This novel mapping system has the potential to increase a successful cure of this arrhythmia by catheter ablation.
Adolescent↗
Relation between ventricular fibrillation voltage and probability of defibrillation shocks. Analysis using Hilbert transforms.
We used Hilbert transforms to re-evaluate the previously reported correlation between defibrillation shock outcome and absolute ventricular fibrillation voltage (AVFV). Previously in the literature, single values of AVFV acquired just prior to shock delivery were used to show a correlation between AVFV and shock outcome. In subsequent studies, a modified analysis procedure was used to show a correlation between shock outcome and moving average of AVFV. The use of single values of AVFV makes the AVFV sensitive to the local phase of the electrocardiographic (ECG) waveform, whereas moving averages are weighted by previous values of the ECG. The envelope is independent of the phase of the ECG and is not weighted by previous values of ECG as is the moving average. We explored, therefore, whether the AVFV computed from the envelopes of the ECG showed a stronger correlation with shock outcome than single values and moving averages of the AVFV. We estimated envelopes using the Hilbert transform. Orthogonal ECGs (sagittal, X; transverse, Y; and longitudinal, Z) were recorded from 11 dogs during 10 seconds of electrically induced ventricular fibrillation followed by a defibrillation shock with 50% probability of success. We used transvenous (right ventricular apex to subcutaneous patch) leads to deliver defibrillation shocks. Results from 236 successful and 249 unsuccessful trials showed, in contrast with the previously reported correlation, that moving average of AVFV was not higher for successful trials. In the Z direction, unsuccessful trials had higher voltage than successful trials (P < .05). Comparison of envelope voltages between successful and unsuccessful trials did not show any consistent and statistically significant differences. Although there were some methodological differences between ours and the previously reported studies, they are unlikely to have caused the discrepant observations. Our results suggest, therefore, that the absolute voltage of ECG during ventricular fibrillation is not robustly correlated with shock outcome.
Animals↗
Tridimensional mapping: guided modification of the sinus node.
Radiofrequency (RF) catheter modification of the sinus node appears to be a promising therapeutic modality for the treatment of inappropriate sinus tachycardia. Modification, as opposed to total obliteration, of the atrial pacemaker requires precise localization of the sinus node. This has been successfully achieved with a multicatheter approach guided by intracardiac echocardiography. This article describes the first clinical use of a tridimensional nonfluoroscopic mapping system to guide successful RF modification of the sinus node in two cases of inappropriate sinus tachycardia. This system simplifies the current approach and greatly reduces the fluoroscopy time.
Adult↗
Bispectral energies within electrocardiograms during ventricular fibrillation are correlated with defibrillation shock outcome.
We investigated whether the degree of phase coupling among orthogonal electrocardiograms during ventricular fibrillation (VF) was correlated with defibrillation shock outcome. We used cross bispectrum to estimate the degree of phase coupling. In dogs, VF was electrically induced and terminated with a defibrillation shock with a 50% probability of success. The defibrillation shock was delivered between the right ventricular apex and a subcutaneous patch electrode. Bispectra were integrated within 8.7-11.7, 8.7-11.7 Hz bandwidths and compared between those trials for which the defibrillation shocks were successful (206 trials, 49%) and unsuccessful (221 trials, 51%) in terminating VF. Results showed that between 200 and 1000 ms before defibrillation shock, unsuccessful trials had greater bispectral energy than successful trials (p<0.05). Although correlations between degree of phase coupling and shock outcome do not indicate causal relationship or predictability, they provide further evidence of the organization during fibrillation. We discuss the nonstationary wavelet hypothesis, previously proposed in the literature by other investigators, as one of the possible mechanisms to explain the correlation between bispectral energy and shock outcome.
Animals↗