Ventricular fibrillation in a patient with three accessory pathways, Ebstein anomaly and intermittent long QT interval. RF ablation and electrophysiologic considerations

We present a case of a 19-year old man with minor Ebstein's anomaly, intermittent long QT interval and WPW syndrome in whom atrial fibrillation, degenerating into ventricular fibrillation was the first symptom. QRS complex morphologies during atrial fibrillation revealed the presence of three accessory pathways (septal, right inferior paraseptal and antero-inferior). Immediately after resuscitation the patient was treated with amiodarone, which resulted in a significant prolongation of QT interval to 700 ms. After RF ablation of accessory pathways patient remains asymptomatic during 6-month follow up, however QTc interval is about 500 ms.     

Effects of verapamil on the electrophysiologic properties of the accessory pathway in patients with the Wolff-Parkinson-White syndrome

The effects of intravenous verapamil on the electrophysiologic properties of the accessory pathway in 12 patients with symptomatic Wolff-Parkinson-White syndrome were studied using intracardiac electrical recordings. In 11 of the 12 patients it was possible to induce a reentrant supraventricular tachycardia with programmed atrial or ventricular pacing. After verapamil it was still possible to induce supraventricular tachycardia in 6 of the 11 patients; however, the mean cycle of length of the tachycardia increased from a control value of 330 ± 20 ms (mean ± standard error of mean) to 369 ± 21 ms (p < 0.05). Although verapamil had no significant effect on the anterograde refractory period of the accessory pathway as measured by the extrastimulus technique, it significantly increased maximal 1:1 atrioventricular (AV) conduction through the accessory pathway to incremental high rate atrial pacing in 10 of the 12 patients (control value 227 ± 10 beats/min, value after verapamil 258 ± 14 beats/min, p < 0.001). In 4 patients in whom episodes of atrial fibrillation could be compared before and after verapamil, the drug decreased the average R-R interval from a control value of 327 ± 27 ms to 282 ± 28 ms (p < 0.05) and decreased the shortest R-R interval between preexcited beats from a control value of 237 ± 21 ms to 209 ± 18 ms (p < 0.05).

It is concluded that in patients with symptomatic Wolff-Parkinson-White syndrome, verapamil may increase the ventricular response through the accessory pathway if atrial fibrillation occurs. This finding, which is of potential clinical significance, could not have been predicted from conventional anterograde refractory period estimations.     

Wolff-Parkinson-White syndrome and atrial fibrillation: Relation between refractory period of accessory pathway and ventricular rate during atrial fibrillation

To assess the relation between the length of the effective refractory period of the accessory pathway and the ventricular rate during atrial fibrillation, we studied two groups of patients with the Wolff-Parkinson-White syndrome: Group I, 17 patients with electrocardiographlcally documented episodes of atrial fibrillation, and Group II, 9 patients without this arrhythmia. In 17 of these 26 patients the effective refractory period of the accessory pathway could be determined by the single test stimulus method during atrial pacing.

After measurement of the refractory period, atrial fibrillation was induced by rapid atrial pacing (400 to 500/min). The duration of the effective refractory period of the accessory pathway was found to correlate with the shortest R-R interval and the mean ventricular rate during documented or induced atrial fibrillation. In nine patients the effective refractory period of the accessory pathway could not be determined because the atrium became refractory while atrioventricular (A-V) conduction was still occurring over this pathway. In these patients the right atrium was regularly paced at rates of up to 280/min. All nine patients had 1:1 A-V conduction over the accessory pathway up to driving rates of 240/min. In five patients conduction still manifested a 1:1 ratio at pacing rates of 280/min. During atrial fibrillation all nine patients had a mean ventricular rate greater than 200/min.

Although factors other than the effective refractory period of the accessory pathway affect ventricular rate during atrial fibrillation in patients with the Wolff-Parkinson-White syndrome, the duration of this period is of value in identifying patients at risk of having life-threatening high ventricular rates when atrial fibrillation occurs.     

胺碘酮对预激综合征合并心房颤动患者射频消融时心房颤动发作的预防作用

探讨胺碘酮对预激综合征合并阵发性心房颤动 (简称房颤 )患者房室旁道电生理特性的影响及其在射频消融术中对房颤发作的预防价值。选择有阵发性房颤史的预激综合征患者 4 7例 ,在行射频消融术前 2周口服胺碘酮0 .2g,每日 2次 ;4 5例未服胺碘酮和其他抗心律失常药者作对照组。心电生理检查测定旁道前传、逆传不应期(ERP) ,记录房室折返性心动过速 (AVRT)的诱发率和房颤的发生次数、发作时间及发作时的心室率 ,所有患者均同时行射频消融治疗。结果 :胺碘酮组旁道前传、逆传ERP均较对照组显著延长 ( 3 19± 4 8vs 2 3 5± 2 6ms ;3 0 5± 5 6vs2 4 0± 2 3ms,P均 <0 .0 1)。射频消融术中旁道存在逆传者在两组间无显著差别 ( 85 .1%vs 87.2 %) ,而胺碘酮组房颤的发作次数显著降低 ( 19.1%vs 60 .0 %,P <0 .0 1) ,发作时间显著缩短 ( 8.2± 4 .3vs2 3 .6± 11.7min ,P <0 .0 1) ,房颤发作时的心室率显著减慢 ( 12 7± 2 8vs 165± 3 4次 /分 ,P <0 .0 1) ,胺碘酮组消融治疗成功率与对照组无显著性差异 ( 10 0 %vs 95 .6%,P >0 .0 5 ) ,但手术操作与X线透视时间均显著低于对照组 ( 115 .6± 4 1.2vs 15 3 .1± 5 0 .6min ;3 5 .8± 16.4vs 4 9.3± 2 0 .2min ,P均 <0 .0 1)。结论 :胺碘酮可以有效预防射频消融     

Electrophysiologic testing in the management of patients with the Wolff-Parkinson-White syndrome and atrial fibrillation

Twenty patients with the Wolff-Parkinson-White (WPW) syndrome and 1 or more episodes of symptomatic atrial fibrillation (AF) due to rapid anterograde bypass tract conduction underwent electrophysiologic testing. The mean ventricular rate during spontaneous AF was 242 ± 56 beats/min (± standard deviation) and the shortest preexcited R-R interval was 194 ± 40 ms. Six patients underwent surgical bypass tract ablation and 14 were treated medically, based on the results of electropharmacologic testing. Over a mean follow-up period of 35 ± 19 months (± standard deviation), only 1 patient treated medically had a recurrence of minimally symptomatic AF. The successful chemoprophylaxis of symptomatic AF was associated with the inability to induce AF and atrioventricular reciprocating tachycardia during drug testing (7 patients) or with the induction of AF with a ventricular rate < 200 beats/min and a shortest preexcited R-R interval of > 250 ms (7 patients). Electrophysiologic testing can identify a subgroup of patients with WPW and AF in whom medical therapy is a suitable alternative to bypass tract ablation.     

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.     

Enhanced A-V nodal conduction (Lown-Ganong-Levine syndrome) by congenitally hypoplastic A-V node.

The basic anatomical substrate of enhanced A-V nodal conduction, manifesting or not as Lown-Ganong-Levine syndrome, is still a controversial issue. We describe the case of a 34-year-old man who presented episodes of ventricular fibrillation. Electrophysiological studies showed that the AH interval was 55 ms, and increased by only 20 ms at paced cycle lengths of 300 ms; atrial pacing induced atrial fibrillation, with a shortest RR interval of 240 ms. Despite verapamil therapy, this patient died suddenly at home. Histological study disclosed a severe A-V node hypoplasia that was evidently congenital in nature; the rest of the conduction system was normal, and no accessory A-V pathways were present. We suggest that enhanced A-V nodal conduction in this patient was due to the developmental defect in the A-V node; this abnormality caused a loss of specific impulse-delaying function, and thus allowed rapid, unfiltered atrial impulses to reach the lower A-V junction and ventricles.     

Evaluation of flecainide acetate in rapid atrial fibrillation complicating Wolff-Parkinson-White syndrome

Flecainide is reported to be effective in patients with paroxysmal tachycardias, but its effect on rapid ventricular response over accessory atrioventricular pathway during atrial fibrillation is not known. The influence of flecainide on various electrophysiological properties of the accessory pathway with special emphasis on ventricular rate during atrial fibrillation was investigated in 9 patients with severe symptomatic Wolff-Parkinson-White syndrome. The shortest ventricular response during atrial fibrillation increased from 218 (190-270) to 320 (240-block) ms. In 4 patients sustained rapid atrial fibrillation converted to sinus rhythm. The rate of circus movement tachycardia decreased from 166/min to 130/min after flecainide, due to a lengthening of retrograde ventriculoatrial conduction time over the accessory pathway. Flecainide caused a significant prolongation of the effective refractory period of the accessory pathway in our subgroup with extremely fast AV conduction during atrial fibrillation and induced a depressant effect on retrograde accessory pathway conduction. This makes the drug very promising for the emergency treatment of dangerous rapid tachyarrhythias complicating this syndrome.     

Paroxysmal atrial flutter and fibrillation associated with preexcitation syndrome: treatment with ajmaline

Ajmaline was administered intravenously to six patients with the Wolff-Parkinson-White syndrome for the acute management of paroxysmal atrial flutter (three patients) or fibrillation (three patients) with a fast ventricular response (over the accessory pathway). Ajmaline increased refractoriness in the accessory pathway in all three patients with atrial flutter and stopped the flutter in one. The drug completely abolished preexcitation in two of the three patients with atrial fibrillation, decreasing the mean ventricular rate of 240 and 300 beats/min to 110 and 180 beats/min, respectively. In the third patient with atrial fibrillation, ajmaline increased refractoriness over the accessory pathway, decreasing the mean ventricular rate of 300 beats/min to 160 beats/min. In two patients ajmaline was continued as an intravenous maintenance infusion until sinus rhythm was restored. It is concluded that ajmaline is an effective drug for the acute management of atrial flutter or fibrillation with a fast ventricular response in patients with the Wolff-Parkinson-White syndrome.     

Atrial fibrillation triggered by postinfarction ventricular premature beats in a patient with Wolff-Parkinson-White syndrome.

The mechanism by which atrial fibrillation is initiated in patients with accessory pathways is not fully understood. Retrograde conduction of ventricular premature beats to the atrium, causing the arrhythmia, is a very rare cause. We report a patient with Wolff-Parkinson-White syndrome (WPW), without previous tachycardias, who presented multiple episodes of paroxysmal atrial fibrillation after having a myocardial infarction. During the electrophysiological (EP) study the patient presented two spontaneous episodes of atrial fibrillation initiated by ventricular premature beats conducted to the atria through the accessory pathway. After successful catheter ablation of the accessory pathway the patient did not present arrhythmia recurrences.     

Enhanced accessory pathway conduction following intravenous amiodarone in atrial fibrillation. A case report

We observed a dangerous increase of ventricular rate following the intravenous administration of amiodarone in a patient with atrial fibrillation and rapid ventricular response associated with the Wolff-Parkinson-White syndrome. The mechanism of enhanced accessory pathway conduction remains speculative. A possible explanation for the shortened antegrade effective refractory period of the accessory pathway is afforded by the hypotensive action of amiodarone or its dissolvent which might trigger beta-adrenergic reflexes. Intravenous amiodarone should be used with caution in patients with atrial fibrillation and rapid ventricular response via an accessory pathway.     

Effect of flestolol on ventricular rate during atrial fibrillation in Wolff-Parkinson-White syndrome

The ultrashort-acting beta blocker flestolol was studied during atrial pacing and atrial fibrillation (AF) in 10 patients with Wolff-Parkinson-White syndrome. Flestolol was given as a 100-micrograms/kg bolus followed by a 10-micrograms/kg/min infusion for 15 minutes. The drug did not alter the antegrade effective refractory period of the accessory pathway or the atrial paced cycle length at which block occurred in the accessory pathway. After flestolol, the percent of preexcited QRS complexes during AF increased (60 +/- 10 vs 87 +/- 5%, p = 0.01). Despite this, the ventricular rate slowed, with increases in mean RR interval (382 +/- 20 vs 416 +/- 22 ms, p = 0.02) and in the shortest interval between preexcited QRS complexes (251 +/- 18 vs 270 +/- 17 ms, p less than 0.01). The effect of isoproterenol 3 to 5 micrograms/min was studied in 5 patients. During atrial pacing, isoproterenol decreased the antegrade refractory period and the atrial paced cycle length of block in the accessory pathway (p less than or equal to 0.05). During AF, it decreased the percent of preexcited QRS complexes, mean RR interval and shortest interval between preexcited QRS complexes (p less than 0.05). Flestolol reversed the effects of isoproterenol both during atrial pacing and AF. Thus, flestolol does not alter conduction over the accessory pathway during atrial pacing, but during AF it slows conduction over the accessory pathway and prevents isoproterenol-mediated increases in ventricular rate. This suggests that in patients with Wolff-Parkinson-White syndrome sympathetic stimulation after the onset of AF enhances conduction over the accessory pathway and is an important determinant of ventricular rate.     

Electrophysiologic effects of lorcainide on the accessory pathway in the Wolff-Parkinson-White syndrome

The electrophysiologic effects of lorcainide, a class I antiarrhythmic agent with local anesthetic properties, were studied in 20 patients with the Wolff-Parkinson-White syndrome. After intravenous administration of lorcainide (2 mg/kg), the sinus cycle length decreased in all patients from 705 ± 117 to 636 ± 94 ms (p < 0.001). The atrioventricular conduction time lengthened from 84 ± 22 to 94 ± 22 ms (p < 3.01) and the QRS duration increased from 92 ± 19 to 120 ± 29 ms (p < 0.001). The effective refractory period of the atrium increased from 230 ± 27 to 243 ± 35 ms (p < 0.05), whereas the ventricular refractoriness was unaffected. Retrograde conduction over the accessory pathway was blocked in 5 of 18 patients after lorcainide; in the remaining 13 patients a prolongation from 107 ± 32 to 162 ± 57 ms (p < 0.001) was found. Anterograde conduction over the accessory pathway was blocked in 6 patients, and in all other patients it increased considerably. Circus movement tachycardia could be induced in 14 patients before and in 10 patients after the drug. The shortest R-R interval during tachycardia lengthened from 326 ± 40 to 364 ± 67 ms (p < 0.05). The tachycardia zone was unaffected by lorcainide. In 15 patients atrial fibrillation was induced. After lorcainide anterograde conduction during atrial fibrillation was blocked (n = 5). The shortest R-R interval over the accessory pathway during induced atrial fibrillation increased from 228 ± 35 to 304 ± 103 ms (p < 0.05). Intravenous administration of lorcainide produced a pronounced negative dromotropic effect on the conduction properties of the accessory pathway. Lorcainide appears to be a promising new antiarrhythmic agent in patients with the Wolff-Parkinson-White syndrome.     

Effect of exercise on ventricular response to atrial fibrillation in Wolff-Parkinson-White syndrome

Ten patients with Wolff-Parkinson-White syndrome underwent cardiac electrophysiological study extended to include the induction of atrial fibrillation at maximum exercise in the upright position. This was performed using a new temporary bipolar lead with a helical active fixation tip for atrial pacing. The highest rate of atrioventricular conduction via the accessory pathway was greater during exercise than at rest in all 10 patients (mean increase 28%). In three cases the resulting ventricular rate exceeded 300 beats/min, but no patient had severe symptoms or ventricular arrhythmias. The exercise induced enhancement of accessory pathway conduction may significantly but unpredictably affect the risk from spontaneous atrial fibrillation especially in patients with coronary artery disease or in those taking antiarrhythmic drugs. The test procedure was sufficiently simple and well tolerated to be included in our routine electrophysiological investigation.     

Effect of exercise on ventricular response to atrial fibrillation in Wolff-Parkinson-White syndrome.

Ten patients with Wolff-Parkinson-White syndrome underwent cardiac electrophysiological study extended to include the induction of atrial fibrillation at maximum exercise in the upright position. This was performed using a new temporary bipolar lead with a helical active fixation tip for atrial pacing. The highest rate of atrioventricular conduction via the accessory pathway was greater during exercise than at rest in all 10 patients (mean increase 28%). In three cases the resulting ventricular rate exceeded 300 beats/min, but no patient had severe symptoms or ventricular arrhythmias. The exercise induced enhancement of accessory pathway conduction may significantly but unpredictably affect the risk from spontaneous atrial fibrillation especially in patients with coronary artery disease or in those taking antiarrhythmic drugs. The test procedure was sufficiently simple and well tolerated to be included in our routine electrophysiological investigation.     

Onset of atrial fibrillation during antidromic tachycardia: Association with sudden cardiac arrest and ventricular fibrillation in a patient with Wolff-Parkinson-White syndrome

Electrophysiologic evaluation in an 18 year old youth with the Wolff-Parkinson-White syndrome who had a sudden cardiac arrest while playing racquetball revealed two types of paroxysmal reciprocating tachycardia: (1) A normal QRS tachycardia with a short ventriculoatrial (V-A) interval fulfilled the criteria for reentry within the atrioventricular (A-V) node; and (2) a wide QRS tachycardia with a QRS configuration of maximal preexcitation was demonstrated to be the result of an antidromic mechanism.During laboratory study, the wide QRS tachycardia spontaneously degenerated into atrial fibrillation. In the basal state, the shortest R-R interval between preexcited QRS complexes was 270 ms, but after infusion of isoproterenol (1.6 μg/min intravenously), the shortest R-R interval became 180 ms. Consequently, this electrophysiologic study suggested that evolution of antidromic reciprocating tachycardia into atrial fibrillation with a rapid ventricular response during exercise-induced catecholamine release may have been the mechanism for ventricular fibrillation in this patient.     

Recurrent episodes of Morgagni-Adams-Stokes syndrome due to degeneration of atrio-ventricular tachycardias into atrial fibrillation in a patient with Wolf-Parkinson-White syndrome

We present clinical problems and the therapy of a 52 year old patient with Wolf-Parkinson-White syndrome and numerous episodes of Morgagni-Adams-Stokes syndrome. In that patient atrio-ventricular tachycardia caused atrial fibrillation. Short refractory period of the accessory pathway and the ventricular muscle allowed for extremely fast ventricular rate with haemodynamic collapse and syncope. Long-term treatment with propafenone or amiodarone did not prevent the arrhythmias. Electrophysiological study pre- and intraoperation including the epicardial mapping were performed several weeks after discontinuation of therapy with amiodarone. The studies revealed left free wall accessory pathway. Dr. A. Biederman and al. performed dissection of the accessory pathway. There were no evidence of conduction through the accessory pathway during the post operation electrophysiologic study. The patient has neither reentrant tachycardias nor atrial fibrillation episodes.     

Clinical and electrophysiological indications for surgical treatment in patients with Wolff-Parkinson-White syndrome]

20 patients with WPW syndrome and recurrent tachyarrhythmias were studied clinically and electrophysiologically. The localization and electrophysiological properties of accessory pathways and other heart structures were estimated before the surgical treatment. 13 patients (pts) suffered syncope in the course of atrial flutter or atrial fibrillation with heart rate greater than 300/min, often proceeding into ventricular fibrillation or atrioventricular tachycardia greater than 260/min, which sometimes proceeds into atrial/ventricular fibrillation. 6 pts experienced dizziness or fainted during tachyarrhythmias or rhythm changes. In 15 pts antiarrhythmic drugs in monotherapy or various combinations did not prevent recurrence of tachyarrhythmias. In 4 of 5 other pts only amiodarone was effective but the drug was discontinued due to serious adverse effects. The lack of good effect of antiarrhythmic drug therapy can be based on mutually unfavorable electrophysiologic properties of the accessory pathways and other heart structures. Pts who experienced syncope had a particularly short effective refractory period (ERP) of the accessory pathways in ante- and retro-grade direction and short ERP of the ventricle muscle. Additionally, there were multiple accessory pathways, heart muscle impairement and frequent ventricular premature beats--factors triggering the tachyarrhythmias.     

Electrophysiological properties of atrial fibrillation with WPW syndrome and the role of procainamide in conversion

Fifty one patients with recurrent episodes of atrial fibrillation associated with WPW syndrome were studied by pre-operative clinical electrophysiogical testing. The results showed that: these patients had an markedly prolonged intra-atrial conduction time (PA intervals: 42.22 +/- 10.93 ms) than the patients only with attack of atrioventricular reentry tachycardia (AVRT) (PA intervals: 17.21 +/- 9.68ms, P less than 0.001). The attack of atrial fibrillation related to an markedly prolonged atrial vulnerable phase and the retrograde conduction of accessory pathway (AP). The clinical results of atrial fibrillation were decided by the antegrade effective refractory period (AERP) of AP. When the shortest R-R (V-V) intervals during attack of atrial fibrillation was shorter than 180ms, the atrial fibrillation spontaneously turned to the ventricular fibrillation. The conversion of atrial fibrillation to sinus rhythm showed that procainamide not only prolonged AERP of AP, which were 248.57 +/- 15.74ms and 388.57 +/- 63.9 ms (P less than 0.001) respectively before and after intravenous procainamide infusion, but also prolonged intra-atrial conduction time significantly, the PA interval before and after intravenous procainamide infusion were 42.22 +/- 10.93 ms and 57.14 +/- 11.12 ms (P less than 0.025) respectively.     

利用单极标测在心房颤动时消融显性房室旁道

对12例预激综合征患者在心房颤动时以单极标测指导消融房室旁道，其中左侧显性旁道9例、右侧显性旁道3例。在消融成功的靶点图上，单极标测的心室激动较体表心电图QRS波群显示预激成分最明显的Delta波平均提前46±7ms。全部病例消融成功。平均随访7．9±5．1个月，除1例右侧旁道4个月后恢复旁道前向传导需再次消融外，其余11例常规和动态心电图既未见Delta波，也无房室折返性心动过速和心房颤动发生。结果提示对于心房颤动合并显性房室旁道的患者，采用单极标测，其图形易于迅速辨认、测量方法亦简单，用以指导消融成功率高。