Internal transvenous low energy cardioversion for the treatment of cardiac arrhythmias.

Low energy endocardial cardioversion was attempted in 23 patients with 30 arrhythmias, of whom only four were receiving additional drug treatment. Four had atrial flutter, five atrial fibrillation, three intra-atrioventricular nodal tachycardia, two atrioventricular re-entrant tachycardia, 13 ventricular tachycardia, and three ventricular fibrillation. A pacing lead with special large surface area electrodes--the active electrode positioned either in the right atrium or in the right ventricular apex and the indifferent electrode in the right atrium, superior vena cava, or inferior vena cava--was used together with a low energy defibrillator. A total of 114 shocks was delivered, 26 of which were atrial. One episode of atrial flutter was terminated, but atrial fibrillation and atrioventricular nodal tachycardia were not terminated in any of the patients. Both patients with atrioventricular tachycardia were successfully treated, as were eight of the patients with ventricular tachycardia. Atrial fibrillation was produced in three patients and non-sustained ventricular tachycardia in one, ventricular tachycardia was accelerated in two, and ventricular fibrillation induced in five. Fourteen patients experienced severe discomfort and seven mild or moderate discomfort, and only one found the procedure painless. One patient was anaesthetised throughout the procedure. Low energy endocardial cardioversion is not universally successful even at the highest energies tolerable, and with the present electrode and pulse waveforms some patients may suffer considerable discomfort.     

The contribution of artificial pacemaking to understanding the pathogenesis of arrhythmias

Right atrial or ventricular pacing was performed on 36 occasions in 26 patients in an attempt to terminate a variety of tachyarrhythmias. Of 16 episodes of atrial flutter, 13 were terminated successfully; in 9 of the 13, sinus rhythm or the patient's pre-flutter rhythm was restored immediately, whereas in 4 patients, intervening atrial fibrillation or unstable atrial flutter occurred. Pacing terminated paroxysmal atrioventricular junctional or paroxysmal atrial tachycardia on 3 occasions; in a fourth patient, this tachyarrhythmia terminated during catheter manipulation. Six episodes of pacemaker-induced ventricular tachycardia were abolished by ventricular pacing. In 2 patients, atrial tachycardia was only transiently suppressed, and in 1 of these patients, d-c cardioversion produced a similar effect. Atrial fibrillation, spontaneously converting to atrial flutter, resulted during pacing for atrial tachycardia with block; the latter arrhythmia returned when the atrial flutter was terminated. Atrial fibrillation in 7 patients remained unaffected by atrial pacing. Based on the different electrophysiologic mechanisms responsible for reentrant excitation and automatic pacemaker discharge, an attempt has been made to determine the pathogenesis of the tachyarrhythmia by its response to pacing.     

Invasive Elektrophysiologie: Komplikationen, Alpträume und deren Management

Most minor side effects of ablation in the right atrium and right ventricle relate to femoral venous catheterization but there is a small risk of severe complications including atrioventricular (AV) block, damage of surrounding structures and thromboembolic events. Impairment of AV conduction can occur during ablation of atrioventricular re-entrant tachycardia, ablation of anteroseptal, mid-septal and parahisian accessory pathways, ablation of ectopic atrial tachycardia originating from the vicinity of the atrioventricular node and when ablating the septal isthmus for typical atrial flutter. Damage of the right coronary artery is a very rare complication after inferior isthmus ablation with high energy. The thromboembolic risk during and after cardioversion and ablation of atrial flutter is higher than previously recognized and anticoagulation therapy decreases this risk. The risk of perforation and tamponade during ablation in the right atrium and right ventricle is very low but particular caution is necessary in thin-walled structures such as the coronary sinus and the upper right ventricular outflow tract. Phrenic nerve injury can be avoided by pacing from the mapping electrode before application of radiofrequency energy at the right atrial free wall. Limitation of power output depending on the site of ablation and titration of energy application with continuous control of temperature and impedance should be considered to minimize the risk of complications.     

Transvenous cardioversion for the management of recurrent ventricular arrhythmias

The efficacy of transvenous cardioversion and defibrillation for treating life threatening spontaneous ventricular arrhythmias was assessed in a study of 17 patients in a cardiac care unit. Eleven had ventricular tachycardia, five had ventricular fibrillation, and one had both. Transvenous cardioversion successfully terminated tachyarrhythmias on 42 separate occasions in ten patients. Stable electrode positions could not be achieved in two patients, recurrent late displacement occurred in one, and four patients had no further arrhythmias requiring cardioversion once the lead was placed. The energy levels required for successful cardioversion ranged from 0.05 J to 25 J for ventricular tachycardia and from 1 J to 25 J for ventricular fibrillation. The nine successful shocks of 1 J or less did not require sedation or general anaesthesia. High energy (25 J) endocardial shocks were unsuccessful in terminating arrhythmias in two patients, one with ventricular tachycardia and the other with both ventricular tachycardia and fibrillation. Minor unwanted effects of endocardial shocks occurred in five patients. These were acceleration of ventricular tachycardia in two patients and complications of pacing via the special lead in three others: failure of sensing occurred in all three and one patient also had a transient rise in pacing threshold. A postmortem examination in one patient who had received three unsuccessful high energy shocks revealed localised endocardial necrosis at the site of the distal electrode. Transvenous cardioversion offers advantages over external cardioversion but at present practical difficulties limit its application to patients with recurrent ventricular arrhythmias that cannot readily be controlled by conventional methods.     

Transvenous cardioversion for the management of recurrent ventricular arrhythmias.

The efficacy of transvenous cardioversion and defibrillation for treating life threatening spontaneous ventricular arrhythmias was assessed in a study of 17 patients in a cardiac care unit. Eleven had ventricular tachycardia, five had ventricular fibrillation, and one had both. Transvenous cardioversion successfully terminated tachyarrhythmias on 42 separate occasions in ten patients. Stable electrode positions could not be achieved in two patients, recurrent late displacement occurred in one, and four patients had no further arrhythmias requiring cardioversion once the lead was placed. The energy levels required for successful cardioversion ranged from 0.05 J to 25 J for ventricular tachycardia and from 1 J to 25 J for ventricular fibrillation. The nine successful shocks of 1 J or less did not require sedation or general anaesthesia. High energy (25 J) endocardial shocks were unsuccessful in terminating arrhythmias in two patients, one with ventricular tachycardia and the other with both ventricular tachycardia and fibrillation. Minor unwanted effects of endocardial shocks occurred in five patients. These were acceleration of ventricular tachycardia in two patients and complications of pacing via the special lead in three others: failure of sensing occurred in all three and one patient also had a transient rise in pacing threshold. A postmortem examination in one patient who had received three unsuccessful high energy shocks revealed localised endocardial necrosis at the site of the distal electrode. Transvenous cardioversion offers advantages over external cardioversion but at present practical difficulties limit its application to patients with recurrent ventricular arrhythmias that cannot readily be controlled by conventional methods.     

Low energy conversion of atrial fibrillation in the sheep.

OBJECTIVES. In this study, the feasibility, efficacy and safety of low energy internal atrial cardioversion were investigated in a sheep model. The relation between the level of energy used for atrial defibrillation and the probability of successful cardioversion was examined. BACKGROUND. Atrial fibrillation is a common clinical arrhythmia that frequently recurs after termination with high energy external cardioversion. In some patients with drug-refractory and poorly tolerated atrial fibrillation, an automatic implantable cardioverter may prove useful by providing rapid restoration of sinus rhythm. METHODS. In 16 pentobarbital-anesthetized sheep, a right atrial spring electrode was implanted percutaneously and a left thoracic cutaneous patch electrode was placed on the thorax. Sustained atrial fibrillation was induced by rapid atrial pacing and terminated by biphasic cathodal shocks synchronized to the R wave of the surface electrocardiogram (ECG). RESULTS. During 768 defibrillation attempts in 16 sheep, the percent of successful cardioversion attempts increased in a dose-response manner, reaching a plateau at the average energy level of 5 J. With greater than or equal to 1.5 and greater than or equal to 2.5 J energy levels, cardioversion was achieved, respectively, in greater than 50% and greater than 80% of attempts. Ventricular fibrillation occurred in 18 (2.4%) of 768 cardioversion attempts; in all 18 cases, the shock was poorly synchronized with the ECG R wave. CONCLUSIONS. Low energy cardioversion of atrial fibrillation to sinus rhythm is feasible with use of a right atrial spring/cutaneous patch electrode configuration. The percent of successful cardioversion attempts depends on the level of energy output, and there is a risk of ventricular fibrillation if cardioversion is poorly synchronized with ventricular depolarization.     

Catheter ablation for cardiac arrhythmias

With the introduction of radiofrequency energy, catheter ablation has become an established technique for managing many cardiac rhythm disturbances. High efficacy and safety have been reported for accessory pathway ablation, selective fast and slow atrioventricular nodal pathway ablation to eliminate atrioventricular nodal reentrant tachycardia (while preserving atrioventricular conduction), atrioventricular junctional ablation to control the ventricular response to atrial tachyarrhythmias, ablation of the right bundle branch to eliminate bundle branch reentrant ventricular tachycardia, and ablation of the site of tachycardia origin in patients with ventricular tachycardia unassociated with structural heart disease. In addition, there has been active investigation into ablation techniques for more complex arrhythmias such as atrial tachycardia, atrial flutter, and ventricular tachycardia associated with structural heart disease.     

Demonstration of macroreentry and feasibility of operative therapy in the common type of atrial flutter

Two patients are described who had recurrent and long-standing atrial flutter of the common type and were referred for electrophysiologic testing and surgical management. In both patients, atrial flutter could be initiated and terminated by programmed stimulation. Atrial endocardial mapping showed earliest activation during flutter at the orifice of the coronary sinus, with activity proceeding to the low atrial septum, high lateral right atrium and low right atrium, respectively. Programmed atrial extrasystoles from the high right atrium at a time when the atrial septal region was refractory advanced atrial flutter in proportion to prematurity of the extrastimulus, while maintaining the low to high activation sequence. Intraoperatively, epicardial atrial mapping revealed a large right atrial reentrant circuit beginning in the posteroseptal region and proceeding superiorly and laterally through the right atrial free wall before returning to its starting point. The narrowest part of the circuit and that showing relatively slow conduction during atrial flutter was observed in the low right atrial tissue between the tricuspid valve ring and the orifices of the inferior vena cava and proximal coronary sinus, respectively. Cryosurgical ablation around the orifice of the coronary sinus and surrounding atrial wall has prevented recurrent atrial flutter over short term follow-up in both patients, although 1 of the patients has required antiarrhythmic therapy for postoperative atrial fibrillation.     

射频消融治疗快速性心律失常的体会

临床安全应用射频导管消融（ＲＦＣＡ）治疗各类快速性心律失常７８０例，总成功率９７．８％。其中房室折返性心动过速（ＡＶＲＴ）５５４例；房室结折返性心动过速（ＡＶＮＲＴ）１８２例；房扑１５例；房颤５例；特发性室速８例；右室流出道室速、室早１４例；致心律失常性右室心肌病（ＡＲＶＣ）２例。本组患者无一例发生血胸、气胸、心包填塞、动脉拴塞、３°房室传导阻滞、室颤等严重并发症。本文特别强调了术前充分准备、术中精确标测定位、细心轻巧操作、严谨控制消融能量和时间，术中与术后严密监护，可以最大程度地降低并发症的发生率。     

External cardiac programmed stimulation for noninvasive termination of sustained supraventricular and ventricular tachycardia

To examine the feasibility of using a noninvasive temporary pacemaker for termination of well-tolerated supraventricular (SVT) and ventricular tachycardia (VT), a standard external demand pacemaker was modified to allow stimulation with single or multiple extrastimuli and overdrive pacing. To evaluate the efficacy, safety and tolerance of external cardiac programmed stimulation, a standard arrhythmia termination protocol was used in 223 tachycardias in 22 patients. The technique of external cardiac programmed stimulation was used in 209 episodes of SVT in 13 patients. It terminated 95% of the episodes with success in 19 of 20 episodes of atrioventricular nodal reentrant tachycardia and 179 of 189 episodes of atrioventricular reciprocating tachycardia. Of 198 episodes of SVT terminated by the technique 168 (85%) were terminated by a single extrastimulus and 28 (14%) by double extrastimuli. Only 2 episodes of SVT required overdrive pacing for termination. External cardiac programmed stimulation did not result in atrial fibrillation or arrhythmia acceleration. Of 14 episodes of sustained monomorphic VT 5 were terminated by external cardiac programmed stimulation. One tachycardia was terminated by a single extrastimulus, 1 by double extrastimuli and 3 by overdrive pacing. Arrhythmia acceleration occurred once and was terminated by endocardial pacing. On 27 separate occasions patient evaluation of maximal discomfort included 4 ratings of mild, 10 of moderate, 11 of severe and 2 of intolerable discomfort. External cardiac programmed stimulation is effective and safe in patients with well-tolerated sustained supraventricular or ventricular arrhythmias.     

Response of atrial flutter to overdrive atrial pacing and intravenous disopyramide phosphate, singly and in combination.

Ten patients who suffered spontaneous paroxysms of atrial flutter were investigated by electrophysiological techniques. Two had overt Wolff-Parkinson-White syndrome; three Lown-Ganong-Levine syndrome; and one a concealed accessory atrioventricular connection. Atrial flutter was initiated, at study, by right atrial pacing and electrograms from the right atrium and coronary sinus were observed for at least five minutes to ensure stable flutter in both atria. Atrial flutter was terminated by 2.5 s or 5 s bursts of atrial pacing at rates 10, 50, or 100 beats/min faster than the intrinsic flutter rate in only two patients. Atrial flutter, which was reinitiated in two patients, was then treated with intravenous disopyramide phosphate, 2 mg/kg body weight, infused over five minutes. In all 10 patients the atrial rate slowed from a mean of 310 +/- 39 beats/min to 217 +/- 27 beats/min and atrial flutter terminated in one case. Though the mean ventricular rate fell from 161 +/- 52 beats/min to 156 +/- 45 beats/min the atrioventricular conduction ratio fell from 2.17 +/- 0.86 to 1.55 +/- 0.59 and four patients were left with symptomatically significant increases of ventricular rate. In seven of nine patients overdrive atrial pacing, repeated after disopryamide, resulted in the conversion of atrial flutter to sinus rhythm. In this study, overdrive atrial pacing and intravenous disopyramide, singly and in combination, terminated atrial flutter in nine of the 10 patients and it is suggested that this method may provide an effective alternative to direct current cardioversion.     

Surgical management of tachyarrhythmias

In this study of surgical procedures for various tachyarrfiythmias, Wolff-Parkinson-White syndrome comprised most of the cases. An endocardial approach was used to ablate accessory pathways. Additional use of cryocoagulation after surgical incision of the atrium, previously routinely performed, is at present only done occasionally for septal accessory pathways.

Ventricular tachycardia (VT) was the next most frequent condition. The surgical procedures for ischemic and nonischemic VTs are completely different, although both are based on the principle of complete electrophysiologic mapping. For ischemic VT, surgery consists of resection of the left ventricular aneurysm and excision or cryocoagulation of the endocardium, or both. For nonischemic VT, either excision of the entire thickness of the myocardium (2.0 × 2.5 cm on average) at the earliest excitation site of the right ventricle and cryocoagulation of the area of delayed potential or only incision and cyrocoagulation of the left ventricle were performed to avoid reduction of the left ventricular cavity.

Ectopic atrial tachycardia was cured by excision of the earliest excitation site without use of a heart-lung machine, when the focus was located in the atrial free wall. Other successful treatments were of reentrant atrial tachycaroia by cryocoagulation, atrial flutter by cryocoagulation of impulse pathways at the coronary sinus and around the atrioventricular node, and a new surgery for atrial fibrillation and flutter, which retained sinus rhythm. Johnson's procedure was used for surgical ablation of atrioventricular nodal reentrant tachycardia.     

Clinical efficacy of dual electrode systems for endocardial cardioversion of ventricular tachycardia: a prospective randomized crossover trial

In order to eliminate the need for epicardial electrodes, two large transvenous catheter electrodes or one catheter and one extrathoracic patch electrode have been proposed as alternative electrode configurations for defibrillation and ventricular tachycardia cardioversion by implantable cardioverter/defibrillators. We compared the efficacy and safety of endocardial shocks delivered through these two electrode systems in man in a prospective randomized crossover study. Twelve patients with sustained ventricular tachycardia and heart disease undergoing electrophysiologic study were evaluated. A transvenous tripolar cardioversion electrode catheter with a large distal defibrillation electrode (surface area, 400 mm2) and proximal defibrillation electrode (surface area, 800 mm2) was positioned in the right ventricular apex with a cutaneous patch electrode placed on the cardiac apex. Sustained ventricular tachycardia was induced at electrophysiologic study. Shocks were delivered using two catheter electrodes only (right ventricular cathode and right atrial anode = method I), and one catheter electrode and cutaneous patch (right ventricular cathode and cutaneous apical patch anode = method II). Synchronized monophasic shocks were delivered using three preselected protocols based on ventricular tachycardia cycle length and morphology. Initial shock energies were 25 joules for polymorphic ventricular tachycardia and ventricular fibrillation, 15 joules for monomorphic rapid ventricular tachycardia (cycle length less than or equal to 300 msec), and 5 joules for monomorphic slow ventricular tachycardia (cycle length greater than 300 msec). Ventricular tachycardia was reinduced and shock energies titrated until cardioversion threshold was obtained. Identical ventricular tachycardia episodes were treated with both methods at each energy level.(ABSTRACT TRUNCATED AT 250 WORDS)     

Intravenous flecainide acetate for the clinical management of paroxysmal tachycardias

Intravenous flecainide acetate (2 mg/kg) was administered to 40 patients undergoing routine electrophysiological evaluation for the investigation of recurrent paroxysmal tachycardias. Ten patients had recurrent atrial flutter, 11 patients had recurrent atrial fibrillation, one of whom also had paroxysmal left atrial tachycardia, and 19 patients had recurrent ventricular tachyarrhythmias (17 with recurrent ventricular tachycardia and 2 with recurrent fascicular tachycardia). Flecainide was administered during tachycardia (over 5 to 10 minutes) to all patients with atrial flutter, to 10 patients with atrial fibrillation, and to 17 patients with ventricular tachyarrhythmias. In the remaining 3 patients with ill-sustained arrhythmias flecainide was administered during sinus rhythm and reinitiation of tachycardia was then attempted. Flecainide restored sinus rhythm in only 2 patients with atrial flutter (20%), in 9 patients with atrial fibrillation (90%), in 12 patients with ventricular tachycardia (80%), and in one of the 2 patients with fasicular tachycardia. Flecainide also successfully terminated the left atrial tachycardia. Two patients experienced proarrhythmic side effects during flecainide administration, one of whom required intervention by cardioversion. Minor dose effects included oral paresthesia, transient drowsiness or dizziness, and occasional visual blurring. Flecainide acetate is an effective antiarrhythmic agent for the acute termination of recent onset paroxysmal atrial and ventricular tachyarrhythmias.     

Administration of adenosine for termination of atrioventricular nodal reentry tachycardia: induction of atrial fibrillation with rapid conduction over an accessory pathway and unmasking of concomitant Wolff-Parkinson-White syndrome

The antiarrhythmic properties of adenosine, its ultra-short half-life and the absence of frequent serious side effects make it a front-line agent in arrhythmia management, especially in the treatment of atrioventricular nodal reentrant tachycardia. Due to a shortening of atrial refractoriness, adenosine can facilitate the induction of atrial fibrillation. Life threatening tachycardias may result from a potential rapid conduction of atrial fibrillation over an accessory pathway especially if the latter one has a short antegrade refractory period. We report a case of a 59 year old female patient in which intravenous administration of adenosine during typical atrioventricular nodal reentrant tachycardia was followed by atrial fibrillation with rapid conduction over a hitherto unknown accessory pathway. After intravenous administration of adenosine the tachycardia was terminated successfully within 38 s. After a short period of asystole, spontaneous atrial fibrillation developed unmasking an antegrade preexcitation with subsequent rapid ventricular response (210 b/min). The three-lead ECG showed a narrow QRS complex tachycardia. Because of spontaneous conversion to sinus rhythm and the absence of hemodynamic compromise there was no need for external cardioversion. During electrophysiological study an antidromic atrioventricular reentrant tachycardia was recorded over a left posteroseptal accessory pathway including antegrade conduction properties only. Because of its ultrashort half-life, serious side effects after adenosine administration are rare. The possibility of life threatening proarrhythmias after intravenous adenosine administration should be taken into consideration if the etiology of a paroxysmal supraventricular tachycardia is not clear and a concomitant Wolff-Parkinson-White syndrome cannot be excluded. As with application of all intravenous antiarrhythmic agents, the administration of adenosine should only be performed if continuous ECG monitoring and cardioversion facilities are available and possible.     

Electrophysiologic effects of penticainide in patients with supraventricular tachycardia

The electrophysiologic effects of the new class-I antiarrhythmic drug pentisomide were investigated after intravenous (5 mg/kg) application in nine patients with atrioventricular nodal reentrant tachycardia and six patients with atrioventricular tachycardia. Pentisomide did not change sinus cycle length, effective refractory period of the right ventricle (ERP-RV), the AV-node (ERP-AVN) and QT interval. Intranodal (AH-interval) and infranodal conduction time (HV-interval), effective refractory period of the right atrium (ERP-A), QRS duration, antegrade effective refractory period of the accessory pathway (ERP-Kent), ventricular cycle length during atrial fibrillation and tachycardia cycle length were significantly (P less than 0.05) increased. Intravenous pentisomide prevented induction of the tachycardia in 5/9 patients with atrioventricular nodal tachycardia and in 2/6 patients with atrioventricular tachycardia. The electrophysiologic properties of pentisomide indicate that it might be a useful drug in the treatment of supraventricular tachycardia.     

Intravenous amiodarone in the acute termination of supraventricular arrhythmias

This study was performed to ascertain whether intravenous amiodarone would revert supraventricular tachycardias to sinus rhythm, and if so, whether this effect depended upon the underlying mechanism of the arrhythmia. Fourteen patients were studied. Seven had Wolff-Parkinson-White (WPW) syndrome, 1 had dual atrioventricular nodal pathways and 1 an ectopic atrial tachycardia. Five patients had atrial fibrillation without accessory pathways. An atrial electrode was inserted to initiate tachycardias and record the electrogram. If tachycardias were stable for more than 5 min, amiodarone (5 mg/kg) diluted with dextrose saline was infused intravenously over 5 min. Two electrocardiographic leads and the right atrial electrogram were monitored. In 7 patients with atrial fibrillation (2 with accessory pathways), 6 did not revert to sinus rhythm, 1 reverted only after 1 hr. In 5 cases without accessory pathways the ventricular rate fell 5-10 min after commencing amiodarone. Four of the 5 patients with WPW syndrome and re-entrant tachycardias returned to sinus rhythm within 6 min of commencing the infusion (atrioventricular and ventriculoatrial times increased by 0-38% and 0-14% respectively). (Tachycardias terminated in the anterograde limb.) Three patients underwent intermittent right atrial stimulation for 1 hr. No tachycardias could be initiated for 30 min post amiodarone. The ectopic atrial tachycardia and that due to dual atrioventricular nodal pathways terminated within 7 and 2 min, respectively, of commencing intravenous amiodarone. Thus the use of intravenous amiodarone would be appropriate in the acute management of sustained supraventricular tachycardias.     

Low energy synchronous transcatheter cardioversion of atrial flutter/fibrillation in the dog

The feasibility and effectiveness of low energy synchronous transcatheter cardioversion of atrial flutter and fibrillation were examined in dogs with talc-induced pericarditis. A conventional electrode catheter was positioned transvenously in the right atrial appendage. Atrial flutter/fibrillation was induced by using the train pulse method, and the tachyarrhythmia-inducing threshold was determined. The minimal effective cardioversion energy levels were compared in three different cardioversion methods: method A = delivery of shock between the proximal electrode (cathode) and the backplate (anode), method B = delivery between the proximal electrode (cathode) and the distal electrode (anode) and method C = conventional external cardioversion. In both methods A and B, all 149 cardioversion attempts were successful with shocks of less than or equal to 5 J. Shocks of less than or equal to 1 J resulted in successful cardioversion in 57 (70%) of 81 attempts, 50 (74%) of 68 attempts and 5 (12%) of 41 attempts with methods A, B and C, respectively. The mean minimal effective cardioversion energy levels were not significantly different between methods A and B (0.62 +/- 0.67 versus 0.58 +/- 0.71 J). Transcatheter cardioversion decreased the defibrillation threshold 3- to 75-fold (mean 6- to 7-fold) from that of transthoracic cardioversion. The defibrillation threshold was not influenced by the inducibility of atrial flutter/fibrillation. There were no complications of heart block, ventricular fibrillation or pathologic evidence of severe shock-induced atrial injury. Thus, low energy synchronous transcatheter cardioversion of atrial flutter/fibrillation is considered feasible and effective. This technique may also be useful in managing the atrial flutter/fibrillation that can occur during electrophysiologic studies.     

Flecainide acetate for conversion of acute supraventricular tachycardia to sinus rhythm

The efficacy of intravenous flecainide acetate (maximum 2 mg/kg or 150 mg given at a rate of 15 mg/min) was assessed in patients with acute supraventricular tachycardia (SVT) (within 24 hours). Fifty patients were studied, 46 with spontaneous SVT and 4 with induced SVT at electrophysiologic assessment. Conversion to sinus rhythm was achieved within 45 minutes in 76%: in 25 patients with atrial fibrillation (76% conversion), 15 with atrioventricular (AV) nodal or AV reentrant tachycardia (100% conversion) and 10 with atrial flutter or atrial reentrant tachycardia (40% conversion). Adverse effects were noted in 21 patients (42%): paresthesia in 9, drowsiness in 8, nausea in 2, accelerated ventricular rate in 5, ventricular tachycardia in 1, sinus bradycardia in 1 and hypotension in 5. Adverse effects were associated with larger dosage and atrial flutter or atrial reentrant tachycardia. Thus, flecainide acetate is effective in converting to sinus rhythm acute atrial fibrillation and AV nodal and AV reentrant tachycardias, but not atrial flutter or atrial reentrant tachycardia.