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PubMed1999

Dofetilide: a review of its use in atrial fibrillation and atrial flutter.

UNLABELLED: Dofetilide is a 'pure' class III antiarrhythmic agent which has demonstrated efficacy in the conversion of atrial fibrillation or flutter to sinus rhythm and the maintenance of sinus rhythm. By blocking the rapid component of the cardiac delayed rectifier potassium current (I(Kr)), dofetilide prolongs the cardiac action potential duration and the effective refractory period. This is thought to increase the likelihood of a re-entrant wavefront encountering refractory tissue and terminating the arrhythmia. Preliminary findings from the EMERALD (European and Australian Multicenter Evaluative Research on Atrial Fibrillation Dofetilide) and SAFIRE-D (Symptomatic Atrial Fibrillation Investigation and Randomized Evaluation of Dofetilide) studies suggest that oral dofetilide is effective in the conversion of atrial fibrillation or flutter to sinus rhythm. Both studies have yet to be published in full. In SAFIRE-D, dofetilide 500microg twice daily for 3 days achieved a conversion rate of 32% compared with a 1% rate for placebo. A similar conversion rate was achieved after 3 days in EMERALD with dofetilide 500microg twice daily (29%) which was significantly greater than that achieved with sotalol 80mg twice daily (6%; p < 0.05). Oral dofetilide also appears to be effective in the maintenance of sinus rhythm. An abstract report of EMERALD participants who had been converted to sinus rhythm showed that 71% of patients who received oral dofetilide remained in sinus rhythm after 6 months (compared with 26% of placebo and 59% of sotalol recipients: both p < 0.05). Restoration of sinus rhythm using intravenous dofetilide is more likely in patients with recent-onset versus prolonged-duration arrhythmia, and in those with atrial flutter rather than atrial fibrillation. Limitations of comparative data for intravenous dofetilide are such that few conclusions can be drawn. Although generally well tolerated in clinical trials, dofetilide has proarrhythmic potential. Torsade de pointes ventricular tachycardia was reported in up to 3.3% of patients who received oral dofetilide in the DIAMOND (Diamond Investigations of Arrhythmia and Mortality on Dofetilide) studies, although only a small proportion of patients in these studies had atrial fibrillation; most episodes occurred within the first 3 days. Whether the propensity of dofetilide for this life-threatening arrhythmia is similar to that of other class III antiarrhythmic agents has yet to be determined. Importantly, the long term use of oral dofetilide in patients at high risk for sudden cardiac death is not associated with an increased risk of mortality, although these DIAMOND findings cannot necessarily be extrapolated to patients with atrial fibrillation. CONCLUSIONS: Dofetilide offers an alternative to currently available antiarrhythmic agents for the pharmacological conversion of atrial fibrillation or atrial flutter to sinus rhythm and for the maintenance of sinus rhythm after cardioversion. However, further comparative data are necessary before its definitive place can be determined.

Animals↗

PubMed2000

Typical atrial flutter ablation: conduction across the posterior region of the inferior vena cava orifice may mimic unidirectional isthmus block.

INTRODUCTION: The aim of this study was to map the low right atrium before and after radiofrequency ablation of the inferior vena cava-tricuspid annulus (IVC-TA) isthmus in patients with typical atrial flutter (AFI) to better understand the electrophysiologic meaning of incomplete or unidirectional block following the ablation procedure and its relationship with AFI recurrence. METHODS AND RESULTS: We performed atrial mapping in 12 patients using a "basket" catheter in the IVC orifice, Halo catheter in the right atrium, and multipolar catheters in the coronary sinus (CS) and His region. In patients in sinus rhythm, atrial activation was analyzed during pacing from the CS and low lateral right atrium (LLRA) before and after ablation. Atrial activation propagated across the isthmus and posterior region of the IVC orifice simultaneously before ablation. Mapping during AF1 in four patients showed that the crista terminalis was a site of functional block. After ablation, evaluation of Halo catheter recordings in three patients showed apparent unidirectional counterclockwise block, whereas analysis of basket catheter recordings demonstrated complete bidirectional block. The apparent conduction over the isthmus during pacing from proximal CS was due to conduction along the posterior part of the IVC orifice, which activated the LLRA despite complete isthmus block. CONCLUSION: Our results demonstrate that limited endocardial mapping may yield a pattern compatible with unidirectional block in the IVC-TA isthmus, although bidirectional block is present at this anatomic level.

Atrial Flutter↗

PubMed2004

Non-contact mapping to guide radiofrequency ablation of atypical right atrial flutter.

OBJECTIVES: This study was aimed at evaluating the efficacy of non-contact mapping and ablation of non-incisional atypical right atrial (RA) flutters. BACKGROUND: The majority of atypical RA flutters were reported in patients after surgical incision of the RA. METHODS: The study group consisted of 15 patients (61 +/- 13 years, 8 males) with atypical atrial flutter (AFL). The RA activation during AFL was delineated using a non-contact mapping system (EnSite 3000 with Precision Software, Endocardial Solutions, St. Paul, Minnesota). The narrowest part of each reentrant circuit was targeted using radiofrequency energy. RESULTS: In all 15 patients, non-contact mapping showed AFLs confined to the RA with RA activation time accounting for 100% of the cycle length (210 +/- 19 ms). During single-loop re-entry in seven patients, the activation wave front circulated around the central obstacle (CO) in the anterolateral wall with conduction through the channel between the CO and the crista terminalis (CT). During figure-of-eight re-entry in eight patients, simultaneous upper and lower loop re-entry through the conduction gap in the CT was found in four patients, and simultaneous upper loop and free-wall single-loop re-entry was observed in four patients. Radiofrequency ablation of the free-wall channel and/or CT gap was effective in eliminating these AFLs in 13 patients. During a follow-up of 16.8 +/- 3.8 months, two patients had recurrence of left AFL, and one had recurrence of atrial fibrillation. CONCLUSIONS: Atypical RA flutters could arise from single-loop or double-loop figure-of-eight re-entry. Radiofrequency ablation of the free-wall channel and/or the CT gap was effective in eliminating these arrhythmias.

Adult↗

PubMed2006

The electroanatomic characteristics of the cavotricuspid isthmus: implications for the catheter ablation of atrial flutter.

INTRODUCTION: Radiofrequency ablation (RFA) of typical AFL is sometimes difficult because of the poor electroanatomic approach to the cavotricuspid isthmus (CTI). The aim of this study was to correlate the anatomy of the CTI between contact mapping (NavX) and right atrial angiography (RAG), and to investigate the impact of the electroanatomic characteristics of the CTI on the RFA of typical atrial flutter (AFL). METHODS: One hundred patients with typical AFL undergoing RFA were studied. The image-guided group consisted of 50 consecutive patients with the guidance of NavX. NavX geometry and RAG were performed to investigate the morphology of the CTI. The bipolar voltages of the CTI were collected during sinus rhythm by a NavX. The control group consisted of 50 consecutive patients with the guidance of conventional fluoroscopy. RESULTS: There was a good correlation between the angiography and NavX for the anatomy of the CTI. The pouch type had a longer length of CTI than the flat type (33.4 +/- 5.0 vs 22.6 +/- 8.4 mm, P < 0.0001) and deeper depth than the concave type (6.5 +/- 2.2 vs 3.7 +/- 0.8 mm, P < 0.0001) on the angiography. The pouch-type CTI had a longer ablation time and larger pulses of RFA than the other two types. The control group had a longer ablation time, fluoroscopy time, and larger pulses of RFA than image-guided group. CONCLUSIONS: The 3-D mapping system provided a good reconstruction of CTI, which may help in the RFA in patients with a complex anatomy of the CTI.

Adult↗

PubMed2004

Characteristics of virtual unipolar electrograms for detecting isthmus block during radiofrequency ablation of typical atrial flutter.

OBJECTIVES: The purpose of this study was to investigate the characteristics of the second component of local virtual unipolar electrograms recorded at the ablation line during coronary sinus (CS) pacing after radiofrequency ablation (RFA) of the cavotricuspid isthmus (CTI) for typical atrial flutter (AFL). BACKGROUND: Radiofrequency ablation of the CTI can produce local double potentials at the ablation line. The second component of unipolar electrograms represents the approaching wavefront in the right atrium opposite the pacing site. We hypothesized that the morphologic characteristics of the second component of double potentials would be useful in detecting complete CTI block. METHODS: Radiofrequency ablation of the CTI was performed in 52 patients (males = 37, females = 15, 62 +/- 12 years) with typical AFL. The noncontact mapping system (Ensite 3000, Endocardial Solutions, St. Paul, Minnesota) was used to guide RFA. Virtual unipolar electrograms along the ablation line during CS pacing after RFA were analyzed. Complete or incomplete CTI block was confirmed by the activation sequence on the halo catheter and noncontact mapping. RESULTS: Three groups were classified after ablation. Group I (n = 37) had complete bidirectional CTI block. During CS pacing, the second component of unipolar electrograms showed an R or Rs pattern. Group II (n = 12) had incomplete CTI block. The second component of unipolar electrograms showed an rS pattern. Group III (n = 3) had complete CTI block with transcristal conduction. The second component of unipolar electrograms showed an rSR pattern. CONCLUSIONS: A predominant R-wave pattern in the second component of unipolar double potentials at the ablation line indicates complete CTI block, even in the presence of transcristal conduction.

Action Potentials↗

PubMed1999

Radiofrequency catheter ablation of common atrial flutter: significance of palpitations and quality-of-life evaluation in patients with proven isthmus block.

BACKGROUND: Creation of a complete bidirectional inferior vena cava-tricuspid annulus isthmus block (CBIB) by radiofrequency catheter ablation is now a well-accepted criterion for prevention of common atrial flutter (AFl) recurrences. However, some patients still complain of palpitations after ablation, and it is not known whether these are related to AFl recurrences or to other arrhythmias. METHODS AND RESULTS: Among 100 consecutive patients referred to our institution for AFl ablation, CBIB was created in 83. There were 54 patients (group A) in whom AFl was the only documented arrhythmia before ablation and 29 patients (group B) in whom atrial fibrillation (AFib) had been documented in addition to AFl. An electrophysiological control study was performed in 40 patients 1 to 3 months after ablation. Arrhythmic events, medications, and functional status were evaluated at midterm follow-up (n=77; 14. 7+/-8.4 months; range, 4 to 34 months). The SF-36 questionnaire and the Symptom Checklist--Frequency and Severity Scale specific for cardiac arrhythmia were used to assess quality of life in 63 patients at long-term follow-up (27.1+/-8.5 months). Recurrence of AFl was documented in only 1 patient 6 months after ablation. AFib was recorded in 28 patients (36.4%), and atypical AFl was found in 3 patients. Thirty-two group A patients (66.7%) and 17 group B patients (58.6%) were still arrhythmia free at midterm follow-up. Even at long-term follow-up and in group B patients, AFl ablation was followed by a clear improvement in quality of life. CONCLUSIONS: Palpitations after creation of CBIB are due mostly to AFib but not to AFl recurrence. This technique provides a significant and persistent clinical benefit and may suppress all atrial arrhythmia in a subset of patients suffering from both AFl and AFib.

Aged↗

PubMed2000

Usefulness of unipolar electrograms to detect isthmus block after radiofrequency ablation of typical atrial flutter.

BACKGROUND: RS morphology of the unipolar electrogram is associated with propagation of the wave front through the exploring electrode, whereas positive uniphasic (R) unipolar electrograms are characteristic of the end of activation. METHODS AND RESULTS: Unipolar electrograms were recorded in 45 consecutive patients with atrial flutter who were undergoing radiofrequency ablation (RFA). Bidirectional cavotricuspid isthmus (CTI) block was achieved in 44 patients. The unipolar electrogram obtained before RFA at the low anterolateral right atrium during coronary sinus pacing changed from RS, rS, or QS to R or Rs in all patients after clockwise CTI block was obtained. The morphology of unipolar electrograms recorded close to the coronary sinus during pacing from the low anterolateral right atrium changed from RS or rS to R or Rs in all but 4 patients after counterclockwise CTI block. In the patient in whom CTI block was not achieved, the RS morphology of the unipolar electrogram remained unchanged. In 18 patients, the results of the RFA were assessed with only the unipolar electrogram. The unipolar electrogram correctly predicted 100% and 89% of the cases of clockwise and counterclockwise CTI block, respectively. CONCLUSIONS: The creation of CTI block is associated with an easily detectable loss of negative components and development of an R or Rs pattern of the unipolar electrogram recorded close to the ablation line while pacing at the opposite side of the CTI.

Aged↗

PubMed2005

Vector mapping in localizing the transverse conduction site of the crista terminalis in patients with typical atrial flutter.

BACKGROUND: The difference in the conduction properties of the crista terminalis (CT) along its course, has not been fully clarified. Using the vector mapping method, we localized the transverse conduction (TC) site of the CT and elucidated its conduction capabilities in patients with typical atrial flutter (AF). METHODS: The TC site of the CT was localized by the analysis of the polarity reversal of the double potentials recorded at 10 sites along the CT using a 20-pole deflectable catheter in 17 patients. The conduction capabilities of the TC site were analyzed during incremental pacing delivered from 100 beats/min to 2-to-1 local capture at the low anterior (LARA) and posterior (LPRA) right atrium. RESULTS: At a pacing rate of 100 beats/min, TC at a single site was observed in 15 patients during LARA pacing and 7 patients during LPRA pacing, respectively. TC sites were distributed from superior to middle third of the CT in all patients. TC was bidirectional in 4 sites, but was unidirectional in the remaining 14 sites. Following an increase in the pacing rate, TC was blocked in all 7 sites during LPRA pacing and 11 of 15 sites during LARA pacing. Shift in the location of the TC site was not observed in any of the patients before TC block. The conduction block rate during pacing from LARA was significantly higher than that from LPRA (211 +/- 59 beats/min vs 145 +/- 66 beats/min, P < 0.01). CONCLUSIONS: The superior to middle third of the CT provides TC capabilities. The TC across the CT was caused by a preferential conduction site and most of these TC were unidirectional, and stable in location irrespective of the change in the conduction rate.

Aged↗

PubMed2001

Atrial flutter ablation: efficacy and cost-effectiveness of a single decapolar electrode to demonstrate bidirectional isthmus block.

AIMS: To evaluate whether a single decapolar electrode is a reliable and cost-effective substitute for the 'Halo' catheter to map the circuit and detect bidirectional isthmus block during atrial flutter (AFL) ablation. METHODS AND RESULTS: Twenty-four patients underwent AFL ablation by using the decapolar electrode in the infero-lateral wall of right atrium (group A) while a 'Halo' catheter was used in 11 patients (group B). Both groups had similar clinical characteristics. Anti-clockwise rotation (20 patients), clockwise (3 patients) or both forms of AFL (1 patient) were detected in group A. All patients in group B had anti-clockwise AFL. Bidirectional isthmus block was completed in 22 patients of group A and in 9 of group B (P=NS) while incomplete isthmus block was detected in 2 patients in each group (P=NS). Mean fluoroscopy and procedure time was 27 +/- 47 min, 107 +/- 36 min in group A and 14 +/- 19 min, 114 +/- 65 min in group B (P=NS). AFL relapsed in 3 patients of group A (follow-up 7 +/- 4 months) and in 2 of group B (4 +/- 2 months). CONCLUSION: A single decapolar electrode is a reliable method to map the circuit and demonstrate bidirectional isthmus block during AFL ablation. The cost of the decapolar electrode is a quarter of that of the 'Halo' catheter. This represents a significant saving particularly for centres with a substantial number of AFL ablations.

Adult↗

PubMed1993

Amiodarone given by three routes to terminate fetal atrial flutter associated with severe hydrops.

BACKGROUND: We describe the concurrent administration of amiodarone using three different routes in order to provide: 1) rapid and adequate fetal loading without giving unduly high doses to the mother, and 2) a maintenance dose to the fetus without risking repeated invasive procedures. CASE: Rapid atrial flutter was seen on ultrasound in a fetus with severe hydrops at 27 weeks' gestation. Following failed transplacental therapy with sotalol and flecainide, amiodarone was administered to the fetus via the intravenous, intraperitoneal, and transplacental routes. Conversion to sinus rhythm and resolution of hydrops followed this treatment. CONCLUSION: Combined triple-route administration of amiodarone to the fetus can be effective in treating supraventricular tachycardia and may have a role in the management of life-threatening fetal arrhythmias refractory to transplacental therapy.

Adult↗

PubMed1972

Effect of -adrenoceptor blocking agents on poststimulatory atrial flutter in the dog, with observations on the participation of adrenergic mechanisms in this experimental arrhythmia.

1. Four beta-adrenoceptor antagonists, viz. (+/-) propranolol (0.5 mg/kg), (-) alprenolol (0.25 mg/kg), practolol (5 mg/kg) and USVC 6524 (20 mug/kg), were tested for their effects on atrial flutter produced by electrical stimulation of the right atrium around the crushed inter-venae-caval bridge in anaesthetized dogs.2. All the drugs reduced atrial and ventricular rates; this was followed by the abrupt termination of flutter and restoration to normal sinus rhythm.3. Since all the drugs (including practolol, which is devoid of local anaesthetic activity) were given in doses just sufficient to block beta-adrenoceptors, it indicated that beta-adrenoceptor blockade was responsible for their antiarrhythmic property in this test procedure.4. Further evidences in support of participation of the sympathetic nervous system in poststimulatory flutter were: (i) flutter could not be produced in nine out of ten dogs whose catecholamine stores were depleted by pretreatment with reserpine; (ii) infusion of adrenaline in these animals resulted in the production of flutter; (iii) duration of flutter after termination of exposure to adrenaline was a few minutes, which is similar to the brief time previously reported to be taken for the disappearance of catecholamines from the hearts of reserpinized animals.5. The clinical significance of the above findings is discussed.

Acetanilides↗

PubMed1998

[Type I atrial flutter radiofrequency ablation. Importance of bidirectional block of isthmus between the inferior vena cava and of tricuspid valve ring].

PURPOSE: To determine the clinical importance of a bi-directional line of block demonstration in the inferior vena cava-tricuspid annulus isthmus as an end-point for radiofrequency (RF) atrial flutter (FL) ablation. METHODS: Forty consecutive patients (51 +/- 11 years) with type I FL were divided in 2 groups: GI (30 patients) anatomic, non-electrophysiologic isthmus ablation technique (interruption and non-induction FL criteria); and GII (10 patients) anatomic with electrophysiologic evaluation of bi-directional isthmus conduction. The isthmus activation was analyzed before and after anatomic RF ablation with a cateter exploring each side of the line of block, depending on the conduction evaluation (anterograde or retrograde). RESULTS: FL was interrupted and not reinduced in 26/ 30 (86.6%) GI patients and in 10 (100%) GII patients (p = 0.5558). During follow-up FL recurred in 30% of the patients in both groups. In GII, 6 patients with bi-directional block remained assymptomatic, whereas 3 patients with unidirectional block presented recurrence (p = 0.012). CONCLUSION: Electrophysiologic demonstration of bidirectional line of block in the isthmus is related to long-term success and should be the criterion for interruption of type I atrial FL RF ablation.

Atrial Flutter↗

PubMed1997

Inappropriate discharge of an implantable cardioverter defibrillator during atrial flutter and intermittent ventricular antibradycardia pacing.

INTRODUCTION: Inappropriate discharges of an implantable cardioverter defibrillator (ICD) are troublesome to the patient and sometimes a difficult task for the physician trying to identify and treat the cause. METHODS AND RESULTS: For the first time, we report a mechanism of inappropriate ICD discharges during episodes of atrial flutter with a slow ventricular response and intermittent antibradycardia pacing. The episodes occurred in two patients and were triggered by the unique sensing algorithm of the Ventritex Cadence V-100 in combination with the tripolar CPI Endotak 072 transvenous defibrillation lead, which provides integrated bipolar sensing. CONCLUSION: Besides treatment of the underlying arrhythmia, reprogramming of the device, an electrode position far away from the atria, and true bipolar sensing will enhance the performance of ICD systems with respect to the episodes described here. In addition, more flexible sensing algorithms may, in the future, prevent this overall rare complication.

Aged↗

PubMed1994

Cardiac lymphoma presenting as atrial flutter in an AIDS patient.

An increasing number of patients with the acquired immunodeficiency syndrome (AIDS) and cardiac lymphoma have been documented. Antemortem diagnosis of cardiac non-Hodgkin lymphoma in AIDS is difficult because of the non-specificity of the clinical findings. Rapid progression of cardiac dysfunction is common after symptoms appear. We report the case of a patient with AIDS and cardiac lymphoma revealed by an atrial flutter.

Atrial Flutter↗

PubMed1973