Treatment of recurrent supraventricular tachyarrhythmias with flecainide or a flecainide and amiodarone combination

The acute electrophysiologic effects and therapeutic efficacy of intravenous and oral flecainide were assessed in 18 patients with recurrent supraventricular tachyarrhythmias, resistant to conventional antiarrhythmic agents. They were 22 to 76 years old (mean 50). Twelve patients underwent electrophysiologic study for the investigation of tachyarrhythmias. Of the whole four patients had functional longitudinal AH dissociation (dual AV pathways). These patients had provocable intra-AV nodal reentrant tachycardia (Group I). Six patients had a direct accessory AV pathway, that showed bidirectional conduction in 5 and retrograde conduction alone in 1 (Group II). These patients had provocable atrioventricular reentrant tachycardia using the accessory pathway as the retrograde limb of the tachycardia circuit. Two patients suffered from automatic supraventricular tachycardia (Group III). Group IV included patients with paroxysmal atrial flutter or fibrillation. The patients of this group did not discontinue chronic treatment with amiodarone. After baseline electrophysiologic evaluation, intravenous flecainide (2 mg/Kg body weight over 5 minutes) was given to patients of I and II group during induced reentrant tachycardia. Flecainide was administered to other patients during spontaneous episodes of tachyarrhythmias. Flecainide resulted in tachycardia termination in all patients of group I and in 4 patients of group II (66%). Tachycardia termination was due to block in the retrograde limb of the circuit. Before termination tachycardia cycle length increased significantly, mainly as the result of an increase in ventriculo-atrial conduction time. After intravenous flecainide therapy, reentrant SVT was non inducible in the patients of group I and in 4 patients of group II. Flecainide was successful in the acute termination of 100% of automatic supraventricular tachycardia and 75% of fibrillation. The patients with atrial flutter developed a faster ventricular rate.(ABSTRACT TRUNCATED AT 250 WORDS)     

Electrophysiologic effects and clinical efficacy of flecainide in children with recurrent paroxysmal supraventricular tachycardia

The electrophysiologic effects of intravenous flecainide were evaluated in 16 patients aged 9 +/- 4 years: 15 with recurrent paroxysmal supraventricular tachycardia (SVT) and 1 with overt accessory pathway and history of syncope. Eleven patients had an accessory pathway; it was concealed in 2, overt in 9 and in 10 of these patients an orthodromic atrioventricular reentrant tachycardia was induced. Five patients without accessory pathway had an atrioventricular nodal reentrant tachycardia. After intravenous flecainide (1.5 mg/kg) the effective refractory period of the atrium and ventricle increased significantly; the anterograde and retrograde effective refractory periods of the atrioventricular node did not. Flecainide blocked retrograde conduction in the accessory pathway in 4 patients (effective refractory period 245 +/- 41 ms) and anterograde conduction in 8 of 9 patients (effective refractory period 284 +/- 57 ms). The mean cycle length of orthodromic reciprocating tachycardia and atrioventricular nodal reentrant tachycardia increased significantly. After flecainide tachycardia was noninducible in 6 patients with orthodromic reciprocating tachycardia and in 1 with atrioventricular nodal reentrant tachycardia. It was inducible but nonsustained (less than or equal to 30 seconds) in 1 patient with orthodromic reciprocating tachycardia and in 3 with atrioventricular nodal reentrant tachycardia. Fifteen patients continued oral flecainide treatment for 19 +/- 11 months.(ABSTRACT TRUNCATED AT 250 WORDS)     

Flecainide acetate in the treatment of supraventricular tachycardias: value of programmed electrical stimulation for long-term prognosis

Twenty patients with recurrent symptomatic supraventricular tachycardia were studied to estimate the efficacy of flecainide in the long-term treatment of these arrhythmias and to evaluate the prognostic value of programmed electrophysiologic stimulation. All patients had their arrhythmia inducible at baseline evaluation. Nine patients had a Wolff-Parkinson-White (WPW) syndrome, five had a concealed bypass tract, and two had dual atrioventricular (AV) nodal pathways. In the remaining patients there was an intraatrial reentry circuit. Previous medication was no to five antiarrhythmic drugs (mean 2.4 drugs). At baseline, a circus movement tachycardia was induced in 12, AV nodal tachycardia was induced in two, atrial tachycardia was induced in three, atrial fibrillation was induced in five, and a flutter was induced in two patients. After flecainide, 2 mg/kg intravenously in 10 minutes, six patients no longer had their arrhythmia inducible. In the WPW patients, atrial fibrillation was no more inducible. In 65% of the patients there was no recurrence during a follow-up period of 11 +/- 10 months. None of the six patients who no longer had their arrhythmia inducible had a recurrence of the tachycardia over a period of up to 3 years. Seven of the other 14 patients (who still had their arrhythmia inducible) had a recurrence of the tachycardia. Positive and negative predictive values are 50% and 100%, respectively. We conclude that flecainide prevents recurrences of supraventricular tachycardias in 65% of patients with inducible supraventricular tachycardias during a mean follow-up of 11 months. Programmed electrical stimulation has a high negative predictive value in this setting. Flecainide is especially effective in preventing atrial fibrillation in patients with WPW syndrome.     

The predictive value of electrophysiologic studies in untreated patients with Wolff-Parkinson-White syndrome

The ability of invasive electrophysiologic studies to predict future arrhythmic events in patients with minimally symptomatic Wolff-Parkinson-White syndrome is not known. To assess this ability, 42 patients with evidence of atrioventricular (AV) pre-excitation on the surface electrocardiogram underwent electrophysiologic studies and were then followed up as outpatients taking no medications. The patients were classified into three groups on the basis of prestudy symptoms: group I, 15 asymptomatic patients; group II, 10 patients with infrequent symptoms but no documented arrhythmias; and group III, 17 patients with one documented episode of supraventricular tachycardia or atrial fibrillation, or both. At electrophysiologic study, the number of patients with short anterograde accessory pathway effective refractory periods and rapid ventricular responses during induced atrial fibrillation did not differ statistically among the three groups. During a mean follow-up period of 7.5 +/- 4.9 years, 11 of the 42 patients had documented arrhythmias: 2 patients from group II and 2 patients from group III had supraventricular tachycardia and 7 patients from group III had atrial fibrillation. All nine patients from group III with subsequent arrhythmias had had clinical atrial fibrillation before study. No patient from group I had an arrhythmia during follow-up. There were no episodes of ventricular fibrillation or sudden cardiac death during follow-up in any of the patients. The only predischarge variables that correlated with the subsequent occurrence of arrhythmias were a history of documented arrhythmias before electrophysiologic study (p less than 0.01) and inducible supraventricular tachycardia at electrophysiologic study (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Prospective evaluation of the coronary sinus anatomy in patients undergoing electrophysiologic study.

BACKGROUND: Previous retrospective studies could find a predominant incidence of coronary sinus (CS) anomalies in patients with accessory pathways and a characteristic anatomy of the CS ostium in patients with atrioventricular nodal reentrant tachycardias (AVNRT). HYPOTHESIS: In the present prospective study, CS angiograms were prospectively performed to analyze the incidence of CS anomalies and to measure the diameters of the CS ostium. METHODS: The study included patients referred for electrophysiologic study and catheter ablation of various tachyarrhythmias. The anatomy of the CS and its side branches was visualized [left anterior oblique (LAO) 30 degrees, right anterior oblique (RAO) 30 degrees] by retrograde angiography in 204 consecutive patients (82 women, 122 men, age 45 +/- 15 years); of these, 120 presented with 123 accessory pathways (45 left-sided, 33 right-sided, 45 septal). The diagnosis in the remaining patients was atrioventricular nodal reentrant tachycardia in 43 cases, atrial tachycardia or atrial fibrillation in 12, and ventricular tachycardia in 15. In 14 patients, the indication for the electrophysiologic study was an unexplained syncope. The CS angiogram was evaluated for anomalies and the size of the CS ostium was manually measured in both projections. RESULTS: Anomalies of the CS defined as diverticula, persistent left superior vena cava, or enlarged CS ostia were found in 18 patients (9%). Of those, CS diverticula were found in nine patients, all with a posteroseptal or left posterior manifest accessory pathway, which was abolished within the neck of the diverticulum in seven patients and at the posteroseptal tricuspid annulus in two patients. Persistence of the left superior vena cava was found in five patients, four had atrioventricular reentrant tachycardia secondary to five accessory pathways (left free wall in four, right midseptal in one), and one patient had atrioventricular nodal reentrant tachycardia (AVNRT). Enlargement of the CS ostium of > 25 mm width was detected in nine patients (5%), of whom four had AVNRT. However, the width of the CS ostium generally did not differ significantly between patients with AVNRT (LAO: 14.4 +/- 5.6; RAO 9.3 +/- 2.4 mm) compared with the control group (LAO 13.4 +/- 4.1; 8.2 +/- 1.9 mm). CONCLUSIONS: Anomalies of the CS as diverticula, persistent superior vena cava, or enlargement of the CS ostium are predominantly found in patients with accessory pathway-related tachycardias. Diverticula of the proximal CS were found in 7% of patients with accessory pathways; in these cases, ablation succeeded mostly by radiofrequency (RF) current delivery in the neck of the diverticulum. Enlargement of the CS ostium was more often seen in patients with AVNRT than in all other patients. However, in general the measurements of the coronary sinus ostium did not significantly differ in patients with AVNRT compared with the control group.     

Electrophysiological effects and clinical efficacy of flecainide in childhood patients with supraventricular reciprocating paroxysmal tachycardia

The electrophysiologic effects of intravenous (i.v.) flecainide were evaluated in 13 patients (pts) with recurrent paroxysmal supraventricular tachycardia (PSVT): 6 pts had an overt accessory pathway, 2 a concealed anomalous pathway and 5 had an idionodal reentrant tachycardia (AVNRT). Another patients with overt preexcitation underwent electrophysiologic testing as part of a diagnostic investigation for syncope. After flecainide the effective refractory period of the right atrium and retrograde AV node, and anterograde and retrograde Wenckebach point significantly increased. The drug blocked retrograde conduction on the accessory pathway in 3 pts whereas anterograde conduction was blocked in all 7 pts with overt anomalous pathway. The mean cycle length of the atrioventricular reentrant tachycardia (AVRT) and of the AVNRT increased respectively from 269 +/- 34 msec to 332 +/- 25 msec (P less than .005) and from 286 +/- 9 msec to 380 +/- 64 msec (P less than .05). After i.v. flecainide, reentrant supraventricular tachycardia was no longer inducible in pts with AVRT and 1 with AVNRT, inducible but non sustained (less than or equal to 30 seconds in duration) in 1 pt with AVRT and in 3 with AVNRT. Thirteen pts continued oral flecainide treatment for a mean of 7.2 +/- 3.6 months (range 3 to 12 months). Tachycardia recurred in all 3 pts whose arrhythmia remained inducible and sustained after i.v. flecainide, and in 1 of 10 pts whose re-entrant supraventricular tachycardia was suppressed (6 pts) or inducible but non sustained (4 pts). Thus flecainide is an highly effective and well tolerated drug for the control of PSVT in infancy. The electrophysiologic drug testing with flecainide predicts its efficacy during chronic therapy in most patients.     

Electrophysiological effects and clinical efficacy of propafenone in children with recurrent paroxysmal supraventricular tachycardia

Twenty-four patients aged 10.1 +/- 4.5 (mean +/- SD) years with recurrent paroxysmal supraventricular tachycardia underwent an electrophysiological study. Eleven patients had an overt and seven had a concealed accessory connection; six patients had no accessory connection. An orthodromic reciprocating tachycardia was inducible in 17 of 18 patients with an accessory connection, and an atrioventricular nodal reentrant tachycardia was inducible in four of six patients without accessory connection. After administration of propafenone, the sinus cycle length decreased. Intra-arterial, intranodal, and His-ventricle intervals and QRS duration increased. The atrial and ventricular effective refractory periods and anterograde and retrograde effective refractory periods of the atrioventricular node increased. The cycle length at which nodal second-degree block occurred increased. Of 18 patients with accessory connection, propafenone prolonged retrograde conduction in all, blocked anterograde conduction in five, and prolonged it in six. The drug terminated the orthodromic reciprocating tachycardia in all 17 patients and the atrioventricular nodal reentrant tachycardia in three of four patients. In three of four patients with atrioventricular nodal reentrant tachycardia and in 15 of 17 patients with orthodromic reciprocating tachycardia, the tachycardia was no longer inducible or nonsustained after propafenone. A follow-up of 26 +/- 10 months revealed that the drug when orally administered to all patients prevented recurrences of tachycardia in 15 of 18 patients with and in four of six patients without accessory connection. The results of short-term drug testing with propafenone predict the response to long-term oral therapy with this drug.     

Accessory pathway and atrioventricular node reentrant tachycardia in elderly patients: Clinical features,electrophysiologic characteristics and results of radiofrequency ablation

Objectives. This study was designed to evaluate the clinical features, electrophysiologic characteristics and results of radio-frequency ablation in elderly patients with accessory atrioventricular (AV) pathways or AV node reentrant tachycardia. Background. Radiofrequency ablation in elderly patients with paroxysmal supraventricular tachycardia has not been well described, and comparative study between elderly and younger patients is limited.Methods. Electrophysiologic studies and radiofrequency ablation were performed in 92 elderly patients (45 with an accessory pathway, 47 with AV node reentrant tachycardia).Results. The elderly patients had poorer electrophysiologic properties in accessory pathways and dual AV node pathways than those of younger patients. The success rate of radiofrequency ablation was similar in elderly and younger patients. However, elderly patients had more complications (14%) in left-sided accessory pathways.Conclusions. Radiofrequency ablation in elderly patients with supraventricular tachycardia was effective. However, it must be performed cautiously in those patients with left-sided accessory pathways.     

Role of intravenous isoproterenol in the electrophysiologic induction of atrioventricular node reentrant tachycardia in patients with dual atrioventricular node pathways

To assess the role of intravenous isoproterenol for the facilitation of electrophysiologic induction of atrioventricular (AV) node reentrant tachycardia, 20 patients with dual AV node pathways who lacked inducible AV node reentrant tachycardia at control study had a constant isoproterenol infusion administered and underwent repeat study. Six (30%) of 20 patients (group I) had inducible AV node reentrant tachycardia during isoproterenol infusion whereas the other 14 (70%) patients (group II) did not. Paroxysmal supraventricular tachycardia was clinically documented in all 6 group I patients compared to 3 (21%) of 14 group II patients (p = 0.002). The sensitivity and specificity of isoproterenol-facilitated induction of AV node reentrant tachycardia were 67 and 100%, respectively. The isoproterenol-facilitated induction of sustained AV node reentry was mediated by resolution of the weak link in anterograde slow pathway in 2 (33%) patients, in retrograde fast pathway in 3 (50%) and in both anterograde slow and retrograde fast pathways in 1 (17%) patient. Four group I patients were given intravenous propranolol, 0.2 mg/kg body weight, and had complete suppression of isoproterenol-facilitated induction of AV node reentry. Thus, intravenous isoproterenol is a rather sensitive and highly specific adjunct to electrophysiologic induction of AV node reentrant tachycardia in patients with dual AV node pathways but without inducible sustained AV node reentry.     

Surgical treatment of accessory atrioventricular pathways and symptomatic tachycardia in children and young adults

Twenty-seven patients aged 21 years or younger (mean 15) with symptomatic tachycardia underwent operation for ablation of an accessory atrioventricular pathway. Six patients had associated Ebstein's malformation of the tricuspid valve. Supraventricular tachycardia had been present for a mean of 5 years. At electrophysiologic study, 4 patients were found to have 2 accessory pathways. Left ventricular free wall pathways were found In 14 patients, right ventricular free wall pathways in 10 and septal pathways in 6. Successful initial ablation of all the pathways was achieved in 26 of the 27 patients. No patient died perioperatively and none had persistent complete heart block. During a mean follow-up of 11 months, no patient had recurrence of an arrhythmia related to the accessory pathway. Thus, the surgical treatment of children and young adults with accessory atrioventricular pathways and symptomatic supraventricular tachycardia is safe and effective. For these patients, unless the tachycardia can be easily controlled with a minimal number of drugs and adverse effects, surgical ablation should be considered early in the clinical course.     

AV reentrant and idiopathic ventricular double tachycardias: complicated interactions between two tachycardias

An electrophysiological study was performed in a 61 year old man with Wolff- Parkinson-White (WPW) syndrome. At baseline, neither ventricular nor supraventricular tachycardias could be induced. During isoprenaline infusion, ventricular tachycardia originating from the right ventricular outflow tract (RVOT) with a cycle length of 280 ms was induced and subsequently atrioventricular reentrant tachycardia (AVRT) with a cycle length of 300 ms using an accessory pathway in the left free wall appeared. During these tachycardias, AVRT was entrained by ventricular tachycardia. The earliest ventricular activation site during the ventricular tachycardia was determined to be the RVOT site and a radiofrequency current at 30 W successfully ablated the ventricular tachycardia at this site. The left free wall accessory pathway was also successfully ablated during right ventricular pacing. The coexistence of WPW syndrome and cathecolamine sensitive ventricular tachycardia originating from the RVOT has rarely been reported. Furthermore, the tachycardias were triggered by previous tachycardias.     

Electrophysiological study of young patients with exercise related paroxysms of palpitation: role of atropine and isoprenaline for initiation of supraventricular tachycardia

Electrophysiological studies were performed in eight patients (four men and four women, mean (SD) age 24 (5) years with paroxysmal attacks of palpitation during or immediately after exercise. Five patients were competitive athletes at college. In two patients spontaneous supraventricular tachycardia during exercise was recorded by ambulatory electrocardiographic monitoring and in another it was induced by treadmill exercise testing. Two had dual atrioventricular nodal pathways, three had manifest atrioventricular accessory pathways, and three had concealed atrioventricular pathways. Programmed stimulation induced sustained supraventricular tachycardia in six patients--in two after intravenous injection of atropine sulphate (1 mg) and in four during infusion of isoprenaline (0.01 microgram/kg/min). In one patient, non-sustained atrioventricular nodal reentrant tachycardia was induced during isoprenaline infusion. In the remaining patient, who had dual atrioventricular nodal pathways, tachycardia was not inducible. AH block prevented maintenance of reentry in five patients. In five patients shortening of the effective refractory period of the atrioventricular node with atropine (one patient) and isoprenaline (four patients) caused sustained supraventricular tachycardia. The present study indicates that treatment with atropine and isoprenaline may be an important factor in the initiation of supraventricular tachycardia in patients with exercise related paroxysms of palpitation.     

Electrophysiological study of young patients with exercise related paroxysms of palpitation: role of atropine and isoprenaline for initiation of supraventricular tachycardia.

Electrophysiological studies were performed in eight patients (four men and four women, mean (SD) age 24 (5) years with paroxysmal attacks of palpitation during or immediately after exercise. Five patients were competitive athletes at college. In two patients spontaneous supraventricular tachycardia during exercise was recorded by ambulatory electrocardiographic monitoring and in another it was induced by treadmill exercise testing. Two had dual atrioventricular nodal pathways, three had manifest atrioventricular accessory pathways, and three had concealed atrioventricular pathways. Programmed stimulation induced sustained supraventricular tachycardia in six patients--in two after intravenous injection of atropine sulphate (1 mg) and in four during infusion of isoprenaline (0.01 microgram/kg/min). In one patient, non-sustained atrioventricular nodal reentrant tachycardia was induced during isoprenaline infusion. In the remaining patient, who had dual atrioventricular nodal pathways, tachycardia was not inducible. AH block prevented maintenance of reentry in five patients. In five patients shortening of the effective refractory period of the atrioventricular node with atropine (one patient) and isoprenaline (four patients) caused sustained supraventricular tachycardia. The present study indicates that treatment with atropine and isoprenaline may be an important factor in the initiation of supraventricular tachycardia in patients with exercise related paroxysms of palpitation.     

Antidromic atrioventricular reentrant tachycardia mimicking ventricular tachycardia in the setting of previous myocardial infarction

The differentiation between ventricular tachycardia and broad-complex supraventricular tachycardia can be extremely difficult, particularly in emergency situations. We report a case of hemodynamically compromising broad-complex tachycardia in a 63-year-old man. The patient had previously sustained an anteroseptal myocardial infarction and had subsequently undergone coronary artery bypass surgery because of triple-vessel coronary artery disease. Intravenous treatment with ajmalin terminated the tachycardia and revealed preexcited QRS complexes compatible with the presence of a left-sided atrioventricular accessory pathway. An antidromic atrioventricular reentrant tachycardia (identical to the clinical tachycardia) was induced during an electrophysiologic study. In conclusion, there are several causes of broad-complex tachycardia, even in patients with previous myocardial infarction, and, where doubt exists, electrophysiologic studies should be performed.     

Indications for modification of coexisting dual atrioventricular node pathways in patients undergoing surgical ablation of accessory atrioventricular connections

Concomitant susceptibility to atrioventricular (AV) node reentrant tachycardia has been demonstrated in certain patients having reentrant tachycardia utilizing accessory AV connections. For those patients undergoing accessory connection ablation, AV node surgical modification may be warranted during the same operative procedure. To assess indications for a combined operative procedure, this study evaluated potential predictors of subsequent spontaneous AV node reentrant tachycardia in patients undergoing ablation of accessory AV connections. Among 62 consecutive patients undergoing surgical ablation of an accessory AV connection, 13 (21%) manifested dual AV node pathways. The latter were identified preoperatively in five patients (four with concealed and one with bidirectional accessory connections) and postoperatively in seven (all seven with bidirectional accessory connections). In one patient with a bidirectional accessory connection, dual AV node pathways could not be demonstrated preoperatively, but AV node reentrant tachycardia was induced. Operative ablation of an accessory connection was successful in all patients. However, postoperatively, 2 of the 13 patients had inducible AV node reentrant tachycardia, 5 had AV node "echo" beats and 6 had no inducible arrhythmia. During 26 +/- 7 months of follow-up study, the two patients with inducible AV node reentrant tachycardia postoperatively had symptomatic AV node reentrant tachycardia. In addition, the one patient with inducible AV node reentrant tachycardia preoperatively had recurrence of this tachycardia 4 months after attempted surgical modification of the AV node. Consequently, although dual AV node pathways appear to be common in patients undergoing surgical ablation of an accessory AV connection (21%), only a small group (3 of 13) of these patients are at risk for subsequent clinical AV node reentrant tachycardia.(ABSTRACT TRUNCATED AT 250 WORDS)     

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.     

Electrophysiologic and antiarrhythmic actions of bepridil : Comparison with verapamil and ajmaline for atrioventricular reentrant tachycardia

Bepridil (2 mg/kg intravenously) was given to 20 patients with atrioventricular (AV) reentrant tachycardia and its effects were compared with those of verapamil (0.15 mg/kg intravenously) in 8 patients and ajmaline (0.75 mg/kg intravenously) in 12. After baseline electrophysiologic measurements, the drugs were given during sustained AV reentrant tachycardia (8 patients had dual AV nodal pathways and 12 had an accessory AV pathway). Verapamil terminated AV reentrant tachycardia in 7 patients and bepridil terminated it in 6. In 8 of the patients who received ajmaline, AV reentrant tachycardia was terminated and in 6 of this group bepridil did so. Bepridil was more successful in terminating AV reentrant tachycardia in those with dual AV nodal pathways than in those with an accessory AV pathway. Bepridil slowed sinus rate by 10% (p <0.0001), whereas verapamil did not change it significantly. Both verapamil and bepridil administration prolonged AV nodal conduction (39% and 44%, respectively), lengthened AV nodal effective refractory period (18% and 17% respectively) and increased the Wenckebach cycle length of the AV node (24% and 25%, respectively) to a significant degree (p <0.05). Bepridil also lengthened atrial and ventricular effective refractory periods (p <0.01) and QT interval (p <0.0001) in the group as a whole; in those receiving ajmaline and bepridil only atrial refractoriness was significantly altered (p <0.05). After treatment for 3 to 5 days with oral bepridil, 19 patients underwent repeat study. There was further slowing in sinus rate and prolongation in both atrial effective refractory period and QT interval; the AV Wenckebach cycle length had returned toward the control level, but was still significantly increased (p <0.01). In the 17 cases in whom reinducibility of AV reentry tachycardla was tested, 7 had no inducible arrhythmia, 6 had non-sustained AV reentrant tachycardia and 4 had sustained but slower tachycardia. Thus, bepridil has both AV nodal and myocardial electrophysiologic actions which suggest a useful role in the treatment and prophylaxis of supraventricular arrhythmias.     

Clinical application of radiofrequency ablation]

I. Radiofrequency ablation of atrioventricular accessory pathway in patients with WPW syndrome: Seventeen accessory pathways in 15 patients with Wolff-Parkinson-White syndrome (WPW) were ablated with radiofrequency current. There were 15 accessory pathways located on the left side of the heart (12 left free wall, 1 posterioseptal, 1 posteriolateral and 1 midseptal) and 2 pathways on the right side (1 right free wall, 1 anterioseptal). 16 accessory pathways (94.1%) in 14 patients were permanently abolished. Plasma CK-Mb, SGOT and LDH increased moderately in 7 cases (46.7%) and decreased to normal level in 3-4 days. Conclusion: catheter ablation of accessory pathways with radiofrequency current is a safe and effective therapeutic method for patients with refractory tachycardias mediated by these pathways. II. Radiofrequency ablation of slow pathways to cure AV nodal reentrant tachycardia: Radiofrequency energy was used to selectively ablate the slow pathways in 8 patients with atrioventricular nodal reentrant tachycardia. The slow pathways in all 8 cases were ablated successfully and no episodes of tachycardia could be induced. The A-H, H-V interval and P-R interval of ECG did not change significantly. The Wenckebach points of atrioventricular node remained unchanged. The effective refractory periods of the fast pathways were shortened in 3 and prolonged in 5 cases after the procedure. There were no severe complications. No tachycardia recurred during the follow-up period between 2 weeks and 7 months.     

Efficacy of propafenone in Wolff-Parkinson-White syndrome: electrophysiologic findings and long-term follow-up

The efficacy and safety of intravenous propafenone was studied in 10 patients with Wolff-Parkinson-White syndrome and in 2 patients with a concealed accessory pathway. During electrophysiologic study, the effect of propafenone on the effective refractory period of the accessory pathway was determined, as well as its effect during orthodromic atrioventricular (AV) reentrant tachycardia and atrial fibrillation. Propafenone caused significant increases in the accessory pathway refractory period, both in the anterograde direction (290 +/- 19 versus 474 +/- 50 ms, p less than 0.05) and in the retrograde direction (238 +/- 15 versus 408 +/- 44 ms, p less than 0.05). Complete anterograde accessory pathway conduction block occurred in four patients. Sustained AV reentrant tachycardia was inducible in 11 patients before administration of propafenone. Drug infusion during AV reentrant tachycardia promptly terminated arrhythmia in 10 of these 11 patients and caused slowing of AV reentrant tachycardia in the remaining patient. Before propafenone, sustained atrial fibrillation was inducible in six patients and nonsustained atrial fibrillation in four patients. After propafenone, no patient had inducible sustained atrial fibrillation. Furthermore, propafenone caused a marked decrease in peak ventricular rate during atrial fibrillation. Eight patients have been treated with oral propafenone and followed up for 12 +/- 2 months. All have remained virtually free of recurrent arrhythmia and none has developed significant side effects. Propafenone is a very promising agent for emergency intravenous therapy as well as long-term oral therapy in patients with Wolff-Parkinson-White syndrome.     

Usefulness of transesophageal electrophysiological study during the ergometric test in the evaluation of supraventricular paroxysmal tachycardia occurring during exertion

Transesophageal electrophysiologic study has recently been proposed for the evaluation of supraventricular arrhythmias. In this report we present 13 cases, with palpitations occurring only during effort, due to a suspected supraventricular tachycardia, in which the usefulness of the transesophageal electrophysiologic study performed during stress test was evaluated. Of these 13 patients, nine were male and four were female, mean age was 29 yrs. Twelve cases had no heart disease, one had a moderate mitral valve insufficiency. Nine cases had a normal ECG, four had a WPW pattern. In 9/13 cases no significant arrhythmia was ever documented, in 1/13 ventricular premature beats were present in the basal ECG, in 1/13 a atrial fibrillation and in 2/13 a supraventricular reciprocating tachycardia was recorded. In all cases a maximal exercise test and a 24-hour Holter monitoring were performed. In all pts a transesophageal electrophysiologic study was performed both at rest and during extra-stimuli and incremental atrial pacing. The end point of transesophageal study was the induction of a sustained (greater than 30") supraventricular tachycardia. RESULTS. Maximal exercise test was negative in 11/13 cases; it showed ventricular premature beats in one case and initiated a supraventricular tachycardia in one. The 24 hour Holter monitoring was negative in 12/13 cases while it showed frequent ventricular premature beats in one. Resting transesophageal electrophysiologic study revealed dual A-V nodal pathways in six pts: in one of them a junctional re-entry was induced; in two a single echo beat was observed, while in three no reentry was observed. In three cases a supraventricular tachycardia was induced which was sustained in one and unsustained (7" and 24") in two cases. In 4 cases transesophageal electrophysiologic study gave no information. Transesophageal stimulation during exercise induced a greater than 30" reciprocating tachycardia in all patients, at work loads of 30-180 watts. Six pts had an intranodal tachycardia (V-A less than 70 msec) a further six pts had a atrioventricular tachycardia involving a Kent bundle (V-A greater than or equal to 70 msec), which was concealed in two, and one had a atrial tachycardia. In four cases (3 with intranodal and 1 with atrioventricular tachycardia), exercise transesophageal study was repeated after chronic therapy with betablockers (sotalol 240 mg/die or metoprolol 200 mg/die). In all cases, after therapy, the induced tachycardia had a longer cycle and in two cases it was induced at a higher work load. In a further two cases flecainide (200 mg/die) was tested. In one case (with atrial tachycardia), the arrhythmia was no longer inducible after therapy, in another case (with intranodal tachycardia) the drug had no effect. CONCLUSIONS. In patients with paroxysmal supraventricular tachyarrhythmias occurring during effort the basal ECG is normal or shows a WPW pattern. The maximal exercise test and 24 hour Holter monitoring give no information in over 90% of cases.(ABSTRACT TRUNCATED AT 400 WORDS)