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PubMed2003

Phased-array intracardiac echocardiography for defining cavotricuspid isthmus anatomy during radiofrequency ablation of typical atrial flutter.

INTRODUCTION: Cavotricuspid isthmus (CTI) topography includes ridges, pouches, recesses, and trabeculations. These features may limit the success of radiofrequency ablation (RFA) of typical atrial flutter (AFL). The aim of this study was to assess the utility of phased-array intracardiac echocardiography (ICE) for imaging the CTI and monitoring RFA of AFL. METHODS AND RESULTS: Fifteen patients (mean age 64 +/- 9 years) underwent ICE assessment (imaging frequency 7.5-10 MHz) before and after RFA of AFL. The ICE catheter was positioned at the inferior vena cava-right atrial junction and the following parameters were measured: (1) CTI length from the tricuspid valve to the eustachian ridge; (2) extent of CTI pouching; and (3) thickness pre/post RFA of the anterior, mid, and posterior CTI. CTI length was 35 +/- 6 mm at end-ventricular systole but shorter (30 +/- 6 mm) and more pouched at end-ventricular diastole (P = 0.02). A pouch or recess was seen in 11 of 15 patients (mean depth 6 +/- 2 mm). The septal CTI was more pouched than the lateral CTI, but the latter had more prominent trabeculations. Trabeculations were seen in 10 of 15 patients, and at these locations the CTI was 4.6 +/- 1 mm thick. Anterior, mid, and posterior CTI thickness pre-RFA was 4.1 +/- 0.8, 3.3 +/- 0.5, and 2.7 +/- 0.9 mm, respectively (P < 0.001 by analysis of variance). ICE guided RFA away from unfavorable CTI features (recesses/thick trabeculations). RFA applications created discrete CTI lesions that coalesced, forming diffuse CTI swelling. Post-RFA thickness was as follows: anterior 4.8 +/- 0.8 mm (P = NS vs pre); mid 3.8 +/- 0.8 mm (P = 0.05 vs pre); and posterior 3.8 +/- 0.8 mm (P = 0.02 vs pre). CONCLUSION: Phased-array ICE permits novel real-time CTI imaging with excellent endocardial resolution and may facilitate RFA of AFL.

Aged↗
PubMed1984

[1:1 atrial flutter in an elderly patient: one of the methods of discovering Wolff-Parkinson-White syndrome. Apropos of a case in an adult].

Atrial flutter with 1:1 atrioventricular conduction giving rise to a ventricular rhythm of 240/min in an 80 year old man was the first sign of the Wolff-Parkinson-White syndrome; all previous electrocardiogrammes had shown no evidence of pre-excitation. It was only on the fifth day of hospitalisation that the ECG showed a short PR interval with a delta wave. This case illustrates that: --all supraventricular arrhythmias with abnormally high ventricular rates (over 220/min in adults) should alert to the possibility of an accessory atrioventricular pathway; --rapid atrioventricular conduction may be the first sign of an accessory pathway; --the differential diagnosis lies between an accessory atrioventricular pathway and an atriohisian tract; --digitalis, which may shorten the refractory period of the accessory pathway, is contraindicated in patients with a Kent bundle.

Aged↗
PubMed2004

Atrial fibrillation after radiofrequency ablation of atrial flutter: preventive effect of angiotensin converting enzyme inhibitors, angiotensin II receptor blockers, and diuretics.

OBJECTIVES: To determine risk factors for the development of atrial fibrillation (AF) after atrial flutter (AFL) ablation; and to study the relation between AF development and periprocedural drug use. METHODS: AFL ablation was performed in 196 patients. The relation between AF occurrence and clinical, echocardiographic, and procedural factors and periprocedural drug use was analysed retrospectively by a Cox proportional hazard method. RESULTS: After a median follow up of 2.2 years, 114 patients (58%) developed at least one AF episode. Factors associated with AF development were the presence of preprocedural AF, a history of cardioversion, and the number of antiarrhythmic drugs used before the procedure. Use of angiotensin converting enzyme (ACE) inhibitors/angiotensin II receptor blockers and diuretics was significantly associated by univariate and multivariate analyses with less development of AF. CONCLUSIONS: A high proportion of patients develop AF after AFL ablation. The incidence of AF is related to pre-ablation AF and its persistence. ACE inhibitors/angiotensin II receptor blockers and diuretics seem to protect against AF.

Angiotensin Receptor Antagonists↗
PubMed2006

Conversion efficacy of intravenous ibutilide compared with intravenous amiodarone in patients with recent-onset atrial fibrillation and atrial flutter.

AIM: The aim of our study was to compare the efficacy and safety of ibutilide and amiodarone (intravenously) in converting recent-onset atrial fibrillation (AF) and atrial flutter (Af) to sinus rhythm (SR). METHODS: The study was prospective, randomized and included 152 (103 men and 49 women) consecutive patients with AF or Af of 3-48 h duration. Ibutilide is a selective class III antiarrhythmic agent which when administered intravenously can terminate AF and Af. Amiodarone is also a class III antiarrhythmic agent that when given intravenously or orally has proved to be more effective than other agents in terminating AF and Af [B.N. Singh, F.V. Mody, B. Lopez, J.S. Sarma. Antiarrhythmic agents for atrial fibrillation: focus on prolonging atrial repolarization. Am J Cardiol 1999 Nov 4; 84: 161R-173R.]. Seventy-nine patients (56 with AF and 23 with Af) that consisted group A were treated with ibutilide. Seventy-three (52 with AF and 21 with Af) consisted group B and were treated with intravenous infusion of amiodarone. RESULTS: The conversion rate of group A (ibutilide) was significantly higher than the conversion rate of group B (amiodarone) (80% vs. 57%, p=0.0054). As regards the kind of arrhythmia separately, for AF there wasn't significant difference (77% vs. 69%, p=ns) whereas for Af ibutilide was superior to amiodarone (87% vs. 29%, p=0.003). The conversion rates of ibutilide didn't differ for AF and Af (77% vs. 87%, p=ns). CONCLUSIONS: Ibutilide is more effective than amiodarone in converting recent-onset Af to SR whereas both drugs are equally effective in converting recent-onset AF to SR.

Acute Disease↗
PubMed1998

[The ablation of atrial flutter. The long-term results after 8 years of experience].

OBJECTIVE: Since the 1990's radiofrequency ablation radiofrequency ablation of atrial flutter has evolved in its methods and results. We have reviewed the long term outcome in 62 patients with typical (common) or reversed (clockwise) flutter undergoing radiofrequency ablation between 1990 and 1997. PATIENTS AND METHODS: Fifty men and 12 women, aged 22-78 years (57 +/- 12) with flutter recurring after cardioversion and antiarrhythmic drugs make this series. Flutter was typical in 59 cases and reversed in 3. There was no heart disease in 14, bronchopulmonary disease in 10, coronary disease in 9, cardiomyopathies in 6 and other processes in the remainder. In 5 cases with previous surgery for atrial or ventricular septal defect, Ebstein's anomaly or myxoma, we treated also a macro-reentry tachycardia around the atriotomy in the right atrium. Radiofrequency ablation was directed to the inferior vena cava-tricuspid isthmus in typical and reversed flutter, and to the isthmus between the inferior end of the atriotomy and the inferior vena cava, in the lateral right atrium, in the atriotomy tachycardias. We subdivided our patients in Group 1 (24 patients), treated until the end of 1994, and Group 2 (38 patients) treated since 1995 using specially designed catheters and trying to produce isthmus block as the endpoint of the procedure. RESULTS: Radiofrequency ablation interrupted flutter in 61 of 62 cases (98.4%), and the atriotomy tachycardia in all 5. The number of application in Group 1 was 18.6 +/- 10.1 vs 12 +/- 10 in Group 2 (p < 0.05). Follow-up was 40 +/- 24 months in Group 1 vs 16 +/- 9.5 in Group 2. Flutter recurred in 58% of Group 1 and 13% of Group 2 patients (p < 0.001), usually 1-3 months after radiofrequency ablation and they were successfully treated by new radiofrequency ablation with a small number of applications. There was no recurrence of atriotomy tachycardia. Atrial fibrillation occurred in 14 patients (23%) (11 paroxysmal, 3 persistent), with equal incidence in both groups. At the end of follow-up 85% of the patients were in sinus rhythm, although 6 needed pacemakers for sinus node dysfunction (3) or AV ablation (3). Antiarrhythmic drugs were used by 46% of patients in Group 1 and 26% in Group 2 (p = NS) for atrial arrhythmias or recurrent flutter. CONCLUSIONS: Radiofrequency ablation is an effective treatment for flutter and macro-reentry atriotomy tachycardia. Progress in methods have improved results significantly. Atrial fibrillation can still be a problem in 20-25% of the patients after flutter control.

Adult↗
PubMedDate not supplied

Successful conversion of fetal atrial flutter with digoxin: report of one case.

A fetus suffering from tachycardia of more than 200 beats per minute was found to have an atrial flutter with two-to-one atrioventricular conductional block by the fetal ultrasonogram at 33 weeks of gestation. The tachycardia was successfully converted to sinus rhythm with maternal digitalization. The heart rate stayed in a normal sinus rhythm after the baby was born, however, an incomplete form of cor triatriatum was noted on the echocardiogram examination.

Adult↗
PubMed1987

Circus movement in the canine atrium around the tricuspid ring during experimental atrial flutter and during reentry in vitro.

A Y-shaped lesion in the right atrium allows induction of atrial flutter in dogs. We recorded the activation sequence during this tachycardia from 96 endocardial bipolar electrodes using intracavitary electrode arrays during 12 separate episodes in three isolated perfused hearts. In each case a reentrant impulse circulated around the tricuspid valve orifice in either a clockwise or counter-clockwise direction. Cutting the pathway terminated the rhythm and prevented its reinduction. There was no discrete segment of markedly slow conduction in the reentrant circuit. The tachycardia cycle length was decreased by methacholine and increased by lidocaine. Reentry was also induced in atrial tissue around the tricuspid orifice when this structure was isolated and superfused in vitro. Tachycardia cycle lengths varied from 205 to 399 msec, depending on the circumference of the ring and temperature. Induction of tachycardia by premature stimulation depended on differences in the duration of the effective refractory period among parts of the ring. Conduction velocity was relatively uniform and was slower during tachycardias than during pacing at long cycle lengths. Analysis of the response to premature stimuli that reset the tachycardia provided evidence for incomplete recovery of excitability between depolarizations during the tachycardia. Fast-response action potentials were recorded throughout the pathway and up to six to eight cell layers deep. Histologic studies showed the supravalvular lamina, a circumferential band of fibers several cell layers below the endocardial surface, to be continuous around the tricuspid orifice. Propagation through this layer best explains the conduction velocities observed in the intact heart during flutter in this preparation.

Action Potentials↗
PubMed1987

Effect of procainamide and N-acetylprocainamide on atrial flutter: studies in vivo and in vitro.

We studied the effects of procainamide and N-acetylprocainamide (NAPA) in a conscious dog preparation of atrial flutter resulting from circus movement around the tricuspid orifice. We also recorded transmembrane potentials of atrial tissues from the circus path in vitro. In 12 instrumented dogs, average flutter cycle length was 157 msec, the duration of the excitable gap was 73 msec, and conduction velocity was 0.75 m/sec. At 4 and 8 mg/kg, procainamide moderately prolonged cycle length, but did not terminate the flutter. At a cycle length of 300 msec procainamide increased effective refractory period (ERP) by 12% and 20% and conduction time by 8% and 19%. At 16 and 32 mg/kg procainamide prolonged cycle length, ERP, and conduction time by 60% to 80% and stopped the flutter in all trials. NAPA, at 16, 32, and 64 mg/kg, increased flutter cycle length by 16%, 16%, and 31%, ERP by 14%, 28%, and 41%, and conduction time by less than 15%. NAPA terminated the flutter in two of six dogs given 32 mg/kg, and three of five dogs given 64 mg/kg. The excitable gap was lengthened by both procainamide and NAPA. Transmembrane potentials showed that at a cycle length from 1000 to 300 msec procainamide (10 mg/liter) increased action potential duration and decreased the first time derivative of phase O of the action potential (Vmax), whereas NAPA (20 mg/liter) increased action potential duration without changing Vmax. These findings show the difficulty of relating drug effects on transmembrane potentials to efficacy in vivo since the former do not necessarily indicate which changes in cellular electrical activity are responsible for efficacy against a particular arrhythmogenic mechanism.

Acecainide↗
PubMed2005

The need for atrial flutter ablation following pulmonary vein antrum isolation in patients with and without previous cardiac surgery.

OBJECTIVES: The aim of this study was to assess the incidence of atrial flutter (AFL) after pulmonary vein antrum isolation (PVAI) in patients with previous cardiac surgery (PCS) in comparison to patients without PCS and to assess the need for AFL ablation in both groups. BACKGROUND: Atrial fibrillation (AF) and AFL often co-exist. Pulmonary vein antrum isolation may be sufficient to control both arrhythmias. However, in patients with PCS, atrial incisions, cannulations, and scar areas may cause AFL recurrence despite elimination of pulmonary vein triggers. METHODS: Data from 1,345 patients who had PVAI were analyzed. Patients with a history of AFL ablation and patients who had concomitant AFL ablation during PVAI were excluded from analysis. Sixty-three patients constituted the PCS group (Group 1, age 57 +/- 13 years, 12 female) and 1,062 patients constituted the non-PCS group (Group 2, age 55 +/- 12 years, 212 female). Patients in Group 1 had larger left atria, higher incidence of AFL pre-PVAI, and lower ejection fraction. RESULTS: There was no significant difference in post-PVAI AF recurrence between Groups 1 and 2, but AFL incidence after PVAI was higher in Group 1 (33% vs. 4%, p < 0.0001). Ablation of AFL in Group 1 patients resulted in an 86% acute success rate and 11% recurrence over a mean follow-up of 357 +/- 201 days. CONCLUSIONS: In patients with PCS, post-PVAI AF recurrence is similar to patients without PCS. However, history of PCS is associated with a higher recurrence of AFL after PVAI. In a significant number of patients with PCS, AFL ablation is required to achieve a cure.

Adult↗
PubMed2005

Long-term efficacy of hybrid pharmacologic and ablation therapy in patients with pilsicainide-induced atrial flutter.

BACKGROUND: Combination therapy with catheter ablation of the cavo-tricuspid isthmus and continued drug therapy, that is, "hybrid therapy," in patients with atrial fibrillation (AF) and drug-induced atrial flutter (AFL) is reported to be an alternative means of achieving and maintaining sinus rhythm. With respect to choosing this method among the rhythm control therapies, its long-term efficacy and the prevalence of AFL in patients with AF are very important and have not been fully elucidated. HYPOTHESIS: The purpose of this study was to investigate the long-term effectiveness of this hybrid therapy and the dose prevalence in Ic drug-induced AFL. METHODS: The subjects were 89 patients (aged 62.4 years, 72 men) with episodes of AF (paroxysmal type: 65, persistent type: 11, permanent type: 13). After 4 weeks of oral pilsicainide administration, the dose was increased in those with no documented AFL. The patients who experienced AFL with pilsicainide (Ic-AFL) underwent ablation. RESULTS: Pilsicainide administration resulted in the common type AFL in 17 patients (19.1%). The pilsicainide plasma concentration in the patients with Ic-AFL was significantly higher than in those without AFL (0.79 +/- 0.41 vs. 0.51 +/- 0.24 microg/ml, respectively, p < 0.01). During a 10-54 (mean 37 +/- 14) month follow-up period, sinus rhythm was maintained in 10 of 12 patients after successful ablation followed by continued antiarrhythmic drug administration. CONCLUSIONS: Hybrid therapy with ablation and high doses of pilsicainide was useful in maintaining sinus rhythm in some selected patients with AF and drug-induced AFL.

Aged↗
PubMed2004

Use of double-potential barrier to identify functional isthmus at the cavotricuspid isthmus for facilitating catheter ablation of isthmus-dependent atrial flutter.

INTRODUCTION: The aim of the study was to identify an alternative target for more effective radiofrequency catheter ablation (RFCA) of isthmus-dependent atrial flutter (AFL). METHODS AND RESULTS: We hypothesized that a functional isthmus formed by preexisting double potential barrier at the cavotricuspid isthmus (CTI) could serve as a new target site for facilitating RFCA of AFL. Forty-three consecutive patients with recurrent isthmus-dependent AFL were studied using three-dimensional navigated magnetic mapping and ablation technique. Twenty patients (47%, group A) were shown to have a narrower functional channel at the CTI (functional isthmus). The remaining 23 patients did not have this feature (53%, group B). In group A, double potentials were clustered near the border of the inferior vena cava (IVC) of the CTI and served as a functional channel along the tricuspid annulus (TA). The interspike interval of double potentials was 87 +/- 26 ms near the IVC border and 45 +/- 17 ms (P < 0.0001) near the TA border of CTI. RFCA targeting at the functional isthmus in group A resulted in interruption of bidirectional transisthmus conduction with fewer radiofrequency pulses (6.7 +/- 4.7 in group A vs 21.1 +/- 17.1 pulses in group B, P < 0.001), shorter ablation line (11.6 +/- 4.0 mm vs 37.8 +/- 7.2 mm, P < 0.0001) with no arrhythmia recurrence. These functional isthmuses were found to be located at the lateral third of CTI in 12 patients, middle third in 7, and medial third in 1. This finding is different from that obtained by the conventional method in group B (lateral in 5, middle in 16, medial in 2, P < 0.038). CONCLUSION: In our study, a functional, rather than anatomic, isthmus formed by preexisting double-potential barrier at the CTI was identified in 47% of patients with isthmus-dependent AFL. It is a useful guide to facilitate RFCA of isthmus-dependent AFL.

Atrial Flutter↗
PubMed2000

Body surface mapping of counterclockwise and clockwise typical atrial flutter: a comparative analysis with endocardial activation sequence mapping.

OBJECTIVES: This study was directed at developing spatial 62-lead electrocardiogram (ECG) criteria for classification of counterclockwise (CCW) and clockwise (CW) typical atrial flutter (Fl) in patients with and without structural heart disease. BACKGROUND: Electrocardiographic classification of CCW and CW typical atrial Fl is frequently hampered by inaccurate and inconclusive scalar waveform analysis of the 12-lead ECG. METHODS: Electrocardiogram signals from 62 torso sites and multisite endocardial recordings were obtained during CCW typical atrial Fl (12 patients), CW typical Fl (3 patients), both forms of typical Fl (4 patients) and CCW typical and atypical atrial Fl (1 patient). All the Fl wave episodes were divided into two or three successive time periods showing stable potential distributions from which integral maps were computed. RESULTS: The initial, intermediate and terminal CCW Fl wave map patterns coincided with: 1) caudocranial activation of the right atrial septum and proximal-to-distal coronary sinus activation, 2) craniocaudal activation of the right atrial free wall, and 3) activation of the lateral part of the subeustachian isthmus, respectively. The initial, intermediate and terminal CW Fl wave map patterns corresponded with : 1) craniocaudal right atrial septal activation, 2) activation of the subeustachian isthmus and proximal-to-distal coronary sinus activation, and 3) caudocranial right atrial free wall activation, respectively. A reference set of typical CCW and CW mean integral maps of the three successive Fl wave periods was computed after establishing a high degree of quantitative interpatient integral map pattern correspondence irrespective of the presence or absence of organic heart disease. CONCLUSIONS: The 62-lead ECG of CCW and CW typical atrial Fl in man is characterized by a stereotypical spatial voltage distribution that can be directly related to the underlying activation sequence and is highly specific to the direction of Fl wave rotation. The mean CCW and CW Fl wave integral maps present a unique reference set for improved clinical detection and classification of typical atrial Fl.

Aged↗
PubMed2006

Substrate mapping to detect abnormal atrial endocardium with slow conduction in patients with atypical right atrial flutter.

OBJECTIVES: The purpose of this study was to investigate the relationship between the abnormal substrate and peak negative voltage (PNV) in the right atrium (RA) with atypical flutter. BACKGROUND: The impact of a local abnormally low voltage electrogram on the local activation pattern and velocity of atrial flutter (AFL) remains unclear. METHODS: Twelve patients with clinically documented AFL were included to undergo noncontact mapping of the RA. The atrial substrate was characterized by the: 1) activation mapping; 2) high-density voltage mapping; and 3) conduction velocity along the flutter re-entrant circuit. The normalized PNV (i.e., the relative ratio to the maximal PNV) in each virtual electrode recording was used to produce the voltage maps of the entire chamber. The protected isthmus was bordered by low voltage zones. RESULTS: Atypical AFL of the RA was induced by atrial pacing in 12 patients, including 10 upper loop re-entry and 2 RA free wall re-entry flutter. These protected isthmuses were located near the crista terminalis. The mean width of the protected isthmus was 1.7 +/- 0.3 cm and mean voltage at the isthmus was -0.91 +/- 0.39 mV. The conduction velocities within these paths were significantly slower than outside the path (0.30 +/- 0.18 m/s vs. 1.14 +/- 0.41 m/s, respectively; p = 0.004). The ratiometric PNV of 37.6% of the maximal PNV had the best cut-off value to predict slow conduction, with a high sensitivity (92.3%) and specificity (85.7%). CONCLUSIONS: Characterization of the RA substrate in terms of the unipolar PNV is an effective predictor of the slow conduction path within the critical isthmus of the re-entrant circuit.

Adult↗
PubMed2002

[Determination of the end-point of the radiofrequency linear lesion in the subeustachian isthmus and its relation to treatment of atrial flutter and fibrillation. Acute and long-term results in 90 patients].

UNLABELLED: Complete subeustachian isthmus (isthmus) block created with radiofrequency (RF) linear lesion eliminates type I. atrial flutter (AFL). The end-point of the procedure is measurable. PATIENTS AND METHOD: Ninety patients (21 F) aged 57.6 +/- 12.5 years underwent RF catheter ablation for AFL. Twenty patients had significant structural heart disease (SHD). Atrial fibrillation (AF) was previously documented in 34 (37.8%) patients. Complete isthmus block served as the end-point of the procedure. RESULTS: Following the first ablation procedure complete isthmus block was achieved in 81 (90%) patients and incomplete isthmus block in 7 (7.8%) patients. First procedure failed in 2 (2.2%) patients. AFL recurred in 6 (6.8%) patients, in 4 (4.9%) out of 81 patients with complete isthmus block and in 2 (28.5%) out of 7 patients with incomplete isthmus block. After repeated successful ablation and creation of complete isthmus block in these 6 patients and in 1 patient with previous ablation failure, complete isthmus block was achieved in 84 (93.3%) patients, incomplete isthmus block in 5 (5.6%) patients and ablation was unsuccessful in 1 patient. During 21 +/- 10.6 (6-45) month follow-up since the last ablation AFL did not recur in any of 89 (98.9%) patients with complete or advanced incomplete isthmus block. AF occurred in 39 (43.3%) patients. Incidence of AF was significantly higher in patients without SHD and with AF previously documented or induced (group 2) (25/43; 58.1%) compared to patients without SHD and no AF documented or induced (group 1) (6/27; 22.2%) (p < 0.01). AF occurred in 40% patients with SHD (group 3), which did not significantly differ from any of the former two groups of patients. In this group AF occurred in 10 out of 12 (83.3%) patients with AF documented prior to ablation, which was significantly more compared to 1 (12.5%) patient out of 8 without documented AF (p < 0.01). CONCLUSION: Complete conduction block over the subeustachian isthmus during catheter ablation has a clearly measurable end-point and represents effective method in permanent cure of AFL. Clinical benefit is reduced by AF, particularly in patients, in whom the arrhythmia was documented prior to ablation. In these patients catheter ablation of AFL can be considered a first step to combined treatment with previously ineffective antiarrhythmic drugs and with other ablation strategies.

Adolescent↗
PubMed1999

Tedisamil in a chronic canine model of atrial flutter.

Tedisamil inhibits several cardiac potassium channels including Ito, Ikr, and the adenosine triphosphate (ATP)-sensitive potassium channel (I(KATP)), which may be important in the initiation and maintenance of atrial arrhythmias. We herein report the efficacy of tedisamil in terminating and protecting against the reinduction of atrial flutter (AFL) in a conscious canine model. Sustained AFL (> 15 min) was induced in eight of 10 mongrel dogs by programmed atrial stimulation (PAS) 2-41 days after producing a surgical barrier to conduction in the right atrium. At the time of surgery, an epicardial electrode was attached to the right atrial appendage for pacing and recording. Normal saline, 1 ml/kg, was infused after 15 min of AFL as placebo. Tedisamil (1.0 mg/kg) was given intravenously after 30 min of sustained AFL while recording surface ECGs and atrial electrograms. Conversion to sinus rhythm was achieved in 10 of 10 trials (eight dogs) in a mean time of 20.5 s (SD, +/- 11.8 s). Tedisamil had a negative chronotropic effect lasting > or =2 h and was protective against the reinduction of AFL. In five dogs, PAS was able to induce AFL in only two of seven trials 2 h after drug infusion. The corrected QT interval (QTc) was lengthened for the first 15 min after tedisamil administration (mean, +/- 39.3 ms; p < 0.05), but thereafter returned to baseline. The QRS interval was not altered by tedisamil. Saline alone, given after 15 min of sustained AFL, converted AFL in one of 11 trials (eight dogs) but did not alter the RR interval, QTc, or QRS interval compared with values measured during AFL. No significant adverse effects of tedisamil were observed. The results indicate that tedisamil is effective in interrupting and/or preventing reinduction of canine AFL, possibly by prolonging atrial refractoriness through inhibition of one or more potassium ion repolarizing currents in atrial muscle. Further studies are required to address the exact mechanism by which tedisamil exerts its antiarrhythmic effect.

Adenosine Triphosphate↗
PubMed1998

Intrauterine therapy of fetal atrial flutter.

An increased awareness of fetal arrhythmias by obstetricians has resulted in a growing number of diagnosed cases of fetal cardiac problems. A fetus with atrial flutter diagnosed at 31 weeks of gestation was successfully converted to normal sinus rhythm in utero by maternal administration with digitalis. The fetal heart rate stayed in a normal rhythm with a maintenance dose of 0.5 mg/day. The fetus was delivered spontaneously at term and the neonatal heart rate has been in normal rhythm without any medical treatment.

Adult↗
PubMed1984

[Successful transvenous electric ablation of the AV conduction system in therapy-refractory atrial flutter].

The technique of closed-chest ablation of the atrioventricular (AV) conduction system was used in 3 patients (53-62 years of age) with atrial flutter not responding to medical management. A persistent third-degree AV block was induced in all patients. Moderate increases in CK and CKMB enzymes but not in Tc-pyrophosphate uptake were observed in these patients. 5 days after the procedure a permanent pacemaker was implanted in each case. We conclude that closed-chest ablation of the AV conduction system is a safe and efficient procedure in selected patients with drug-resistant supraventricular arrhythmias.

Adult↗