Radiofrequency catheter ablation for paroxysmal supraventricular tachycardia: a report of 135 procedures

BACKGROUND

Paroxysmal Supraventricular Tachycardia (PSVT) is a common condition which until recently has been treated with anti-arrhythmic drugs or surgery. Radiofrequency (RF) catheter ablation is a new mode of treatment which provides a cure of this condition.

AIMS

To present our early experience of RF catheter ablation for PSVT.

METHODS

One hundred and thirty-five procedures were performed in 117 patients. The diagnostic study and therapeutic catheter ablation were performed as a combined electrophysiological procedure in 74 patients (63%). In 58 patients (50%), PSVT was due to Atrio-ventricular junctional (nodal) re-entrant tachycardia (AVJRT). Twenty-five of the 58 patients underwent a fast pathway ablation while 33 had ablation of their slow pathway. The mean number of radiofrequency pulses delivered was ten for a mean duration of 25 seconds. Radiofrequency ablation of accessory pathways was attempted in 58 patients; pathways were left-sided in 29 patients, postero-septal in 21, midseptal in five, Mahaim connection in two, antero-septal in one and right free wall in one patient. One patient with incessant automatic atrial tachycardia also underwent a successful RF ablation.

RESULTS

Using RF ablation cure of PSVT was achieved in 90% of patients. Cure of AVJRT was achieved in 95% (55/58) of patients using either fast or slow pathway ablation. Only one patient required permanent pacemaker implantation for Mobitz type I AV block following fast pathway ablation. The overall success rate for ablation of accessory pathways was 85%. There is an operator learning curve for this procedure suggested by the fact that the success rate for accessory pathway ablation at first attempt was 63% in the first 29 patients and 93% in the remaining 29. There was no significant morbidity or mortality during or after the procedure. In a mean follow-up of nine months in the patients with successful ablation only two patients with AVJRT had a recurrence of documented PSVT. Both these patients had successful repeat RF ablation. Catheter ablation using radiofrequency energy is an effective and safe therapeutic option for patients with symptomatic PSVT.

Implantable cardioverter-defibrillator therapy in the absence of significant symptoms. Rhythm diagnosis and management aided by stored electrogram analysis

BACKGROUND

This report describes the value of stored ventricular electrogram analysis in the diagnosis and management of patients experiencing minimal or no symptoms before implantable cardioverter-defibrillator (ICD) therapy.

METHODS AND RESULTS

The study population included 48 patients who received the Cadence Tiered Therapy Defibrillator System, an investigational third-generation ICD with ventricular electrogram storage capabilities. Criteria for arrhythmia diagnosis were based on analysis of the electrogram rate, RR interval variability, and morphology. Twenty-nine of the 48 patients (60%) experienced at least one episode of antitachycardia pacing or shock (one shock or more in 25 of 29 patients) that was preceded by minimal or no symptoms during a mean follow-up of 15.1 +/- 7.8 months. There were 194 tachycardia episodes registered by the device, including 101 for which ventricular electrograms were stored and available for analysis. Of the 101 stored electrograms, 74 were classified as ventricular tachycardia (VT), 24 as non-VT rhythms (atrial fibrillation, 13; supraventricular tachycardia, six; rate-sensing lead disruption, four; T wave oversensing, one), and only three as indeterminate rhythms. Based on the electrogram analysis, changes in tachycardia detection criteria and/or antiarrhythmic drug regimens were implemented and were associated with a reduction in the number of device responses for non-VT rhythms from 24 during the initial study period to three during 11.0 +/- 7.2 months of additional follow-up.

CONCLUSIONS

ICD responses in the absence of symptoms are relatively common in third-generation devices with antitachycardia pacing capabilities. Despite potential limitations such as the effect of bundle branch block on the electrogram morphology during supraventricular tachycardia, the availability of electrogram storage capabilities allowed a presumptive diagnosis of the events precipitating asymptomatic device responses. Device reprogramming based on analysis of stored electrograms was associated with a dramatic reduction in the incidence of ICD responses for non-VT rhythms.

Out-of-hospital symptomatic supraventricular arrhythmias. Epidemiological aspects derived from 10 years experience of the Florence Mobile Coronary Care Unit

The epidemiologic features and the relative incidence of symptomatic supraventricular tachycardias in out-of-hospital settings are unknown. Rhythm disturbances account for 20% of the interventions performed by the Florence Mobile Coronary Care Unit (MCCU). Between November 1979 and December 1989, the MCCU rescued 1239 patients with recent onset (less than 24 hours) symptomatic supraventricular arrhythmias. 809 had atrial fibrillation, 376 paroxysmal supraventricular tachycardia (PSVT), 36 atrial flutter and 18 different atrial dysrhythmias. Women showed an overall predominance, more evident in patients with PSVT, and the incidence of the arrhythmias increased with age. Preexisting heart disease was more frequent in atrial fibrillation (41.1%) and atrial flutter (33.4%) in comparison to PSVT (27.6%). Similarly, a higher incidence of associated cardiovascular events (AMI, acute coronary insufficiency, pulmonary edema) was found in patients with atrial fibrillation and atrial flutter. Palpitations were the main complaint in each group, however, in atrial fibrillation and atrial flutter they were frequently associated with chest pain or dyspnea.

Spontaneous occurrence of symptomatic paroxysmal atrial fibrillation and paroxysmal supraventricular tachycardia in untreated patients

BACKGROUND

Ambulatory outpatients (n = 150) with a history of paroxysmal supraventricular arrhythmia were studied to establish the characteristics of the first recurrence of symptomatic tachycardia (time to first recurrence, heart rate during tachycardia, and observed rhythm that was regular versus irregular) when no antiarrhythmic drug was being taken. Baseline variables were examined to assess their impact on time to first recurrence: index arrhythmia (paroxysmal atrial fibrillation [n = 37] versus paroxysmal supraventricular tachycardia [n = 113]), age (mean +/- SD, 43.3 +/- 16.1 years), female sex (n = 71), or presence of other heart or lung disease (n = 53).

METHODS AND RESULTS

Transtelephonic monitoring of the ECG was used to document the rhythm during recurrences of symptomatic tachycardia. Time to first recurrence of symptomatic tachycardia and heart rate during tachycardia were measured, the observed rhythm was classified as irregular (consistent with paroxysmal atrial fibrillation) or regular (consistent with paroxysmal supraventricular tachycardia), and the hour of recurrence was recorded. Advancing age was significantly associated with a decreasing time to first recurrence (p < 0.001); the estimated increase in the hazard function was 25% with each 10 years of advancing age. After the effect of age was adjusted for, neither the classification of arrhythmia (p > 0.2), presence of other heart or lung disease (p > 0.8), nor sex (p > 0.9) was significantly associated with time to first recurrence. Among patients with paroxysmal supraventricular tachycardia, 6.5% had atrial fibrillation recorded at the next symptomatic arrhythmia; among patients with paroxysmal atrial fibrillation, 11.8% had a regular tachycardia recorded at the next symptomatic arrhythmia. There was a circadian pattern to the hour of occurrence of paroxysmal supraventricular tachycardia but not paroxysmal atrial fibrillation.

CONCLUSIONS

Age is more important than other clinical variables, including the ECG classification of a paroxysmal supraventricular arrhythmia in predicting the occurrence of symptomatic arrhythmias. Arrhythmias documented by ECG during symptoms are often different from the arrhythmia documented at the time of referral, which may confound interpretation of antiarrhythmic drug effects.

Risks of developing supraventricular and ventricular tachyarrhythmias after implantation of a cardioverter-defibrillator, and timing the activation of arrhythmia termination therapies

The clinical courses of 39 consecutive recipients (mean age 61 +/- 12 years, and mean left ventricular ejection fraction 0.32 +/- 0.15) of an automatic implantable cardioverter-defibrillator (ICD) were examined to determine the risks of developing ventricular tachycardia (VT) and supraventricular tachyarrhythmias (SVT) after surgery, with ventricular response rates fulfilling ICD detection criteria. ICD system leads were implanted by thoracotomy in 25 patients and by using nonthoracotomy lead systems in 14. Six patients (18%) developed SVT after surgery, whereas 14 (36%) developed sustained VT. The median times to the development of both SVT and VT were 2 days. By actuarial analysis, the probability of developing VT after surgery was significantly greater than that of SVT during hospitalization (p = 0.04). This significant excess of postoperative VT over SVT was most marked in patients aged < or = 61 years, those who received nonthoracotomy rather than epicardial lead systems, those who presented with VT rather than ventricular fibrillation, and those who received > 20 intraoperative defibrillation shocks. These observations recommend the activation of ICD therapies immediately after implantation.

Comparison of high energy direct current and radiofrequency catheter ablation of the atrioventricular junction

OBJECTIVES

The goal of the study was to determine short- and long-term success and complications of radiofrequency atrioventricular (AV) junction catheter ablation and to compare these with those of high energy direct current catheter ablation.

BACKGROUND

Catheter ablation of the AV junction with radiofrequency or direct current energy is an accepted treatment for drug-refractory supraventricular tachycardias. Few data are available on the long-term success and effects of radiofrequency ablation or its comparison with direct current ablation.

METHODS

Fifty-four patients who underwent attempted AV junction ablation with radiofrequency energy were followed up for a mean of 24 +/- 8.4 months. These patients were retrospectively compared with 49 patients who underwent attempted AV junction ablation with direct current energy and were followed up for a mean of 41 +/- 23 months.

RESULTS

The early success rate at the time of discharge for radiofrequency ablation was 81.5%, which was not statistically different from that for direct current ablation (85.7%). Fewer sessions were required to achieve complete AV block in the radiofrequency group (1.05 +/- 0.23) (mean +/- SD) compared with the direct current group (1.21 +/- 0.41) (p = 0.02). Although overall complication rates were similar for both groups (9.3% in the radiofrequency group and 8.2% in the direct current group), there was a trend toward more life-threatening early complications in those patients who received direct-current shocks (6.8%) than in those who underwent radiofrequency ablation alone (2.3%) (p = 0.1). Early sudden death (one patient), early ventricular tachycardia (two patients) and cardiac tamponade (one patient) were seen only in those patients who underwent ablation with direct current energy, whereas pulmonary embolism (one patient) was the only early life-threatening complication in the radiofrequency group. During follow-up, the rate of recurrence of AV conduction was the same (5%) for both the direct current and radiofrequency groups. In the direct current group, one patient died suddenly 2 weeks after the procedure and another had a cardiac arrest due to ventricular tachycardia 6 h after the procedure. In the radiofrequency group, two patients died suddenly at 11 and 7 months, respectively. Two patients, one who had unsuccessful radiofrequency ablation and required direct current ablation, were resuscitated from ventricular tachycardia.

CONCLUSIONS

Radiofrequency energy appears to be as efficacious as and perhaps safer than direct current energy for AV junction ablation.

Comparison of the electrophysiologic effects of oral sustained-release and intravenous verapamil in patients with paroxysmal supraventricular tachycardia

The electrophysiologic effects of intravenous verapamil (0.15 mg/kg) and oral sustained-release verapamil (verapamil-SR) (240 mg once daily for 7 days) were studied in 17 patients with paroxysmal supraventricular tachycardia (SVT). Ten patients had atrioventricular (AV) nodal reentrant tachycardia and 7 had AV reciprocating tachycardia involving an accessory AV pathway. Both preparations significantly prolonged anterograde effective refractory period of the AV node and depressed the retrograde AV nodal conduction system. The sinus cycle length, and atrial and ventricular effective refractory periods were prolonged after oral verapamil-SR. Furthermore, oral verapamil-SR depressed retrograde accessory pathway conduction which was not interfered with by intravenous verapamil. Intravenous verapamil and oral verapamil-SR prevented induction of sustained SVT in 12 of 17 (71%) and 10 of 17 (59%) patients, respectively. Follow-up study with oral verapamil-SR 240 mg once daily in 15 patients for 19 +/- 6 months revealed that among the 8 patients without induction of sustained SVT, 7 have been free of symptomatic arrhythmia; only 1 patient had occasional SVT attacks. For the 7 patients with induction of sustained SVT, 3 patients failed to respond to oral verapamil-SR, 1 patient became symptom free, and the remaining 3 patients had less frequent SVT attacks. Thus, immediate intravenous verapamil testing predicts the electrophysiologic results of oral verapamil-SR therapy, and oral verapamil-SR once daily may be used for long-term prophylaxis of SVT with better patient compliance.

Differentiation of paroxysmal narrow QRS complex tachycardias using the 12-lead electrocardiogram

OBJECTIVES

The purpose of this study was to evaluate the utility of the 12-lead electrocardiogram (ECG) for differentiating paroxysmal narrow QRS complex tachycardias.

BACKGROUND

Previous studies evaluating the utility of the 12-lead ECG for differentiating paroxysmal supraventricular tachycardia types have shown conflicting results on the usefulness of some ECG criteria, and some criteria that are considered to be useful have never been formally evaluated.

METHODS

Two hundred forty-two ECGs demonstrating paroxysmal narrow QRS complex (< 0.11 ms) tachycardia (rate > or = 120 beats/min) were analyzed. All ECGs were analyzed by an observer who had no knowledge of the mechanism of the tachycardia.

RESULTS

There were 137 atrioventricular (AV) reciprocating tachycardias, 93 AV node reentrant tachycardias and 12 atrial tachycardias. Six criteria were found to be significantly different between tachycardia types by univariate analysis. A P wave separate from the QRS complex was observed more frequently in AV reciprocating tachycardia (68%) and atrial tachycardias (75%). A pseudo r' deflection in lead V1 and a pseudo S wave in the inferior leads were more common in AV node reentrant tachycardia (58% and 14%, respectively); QRS alternans was present more often during AV reciprocating tachycardia (27%). When a P wave was present, an RP/PR interval ratio > or = 1 was more common in atrial tachycardias (89%). During sinus rhythm, manifest pre-excitation was observed more often in patients with AV reciprocating tachycardia (45%). By multivariate analysis, the presence of a P wave separate from the QRS complex, pseudo r' deflection in lead V1, QRS alternans during tachycardia and the presence of pre-excitation during sinus rhythm were independent predictors of tachycardia type. These criteria correctly identified 86% of AV node reentrant tachycardias, 81% of AV reciprocating tachycardias and incorrectly assigned the tachycardia type in 19% of cases.

CONCLUSIONS

Several features on the ECG are useful for differentiating supraventricular tachycardia type. However, approximately 20% of tachycardias may be incorrectly classified on the basis of analysis of the ECG; therefore, the ECG should not serve as the sole means for determining tachycardia mechanism.

[The late results of fulguration of the atrioventricular node using high-energy shocks in patients with supraventricular tachycardias]

PURPOSE

To evaluate the long-term efficacy and safety at long term after atrioventricular junction fulguration (complete AV block induction, using high energy shocks, to control drug-resistant supraventricular tachyarrhythmias.

METHODS

Twenty-eight patients, 17 (60.7%) men, with mean age 48.1 years, were submitted to one up to six ablation sessions with high energy shocks. The total delivered energy per patient was 1304 +/- 868 J. Each shock ranged from 100 to 400 J.

RESULTS

After 12 months, at least, 60.6% of patients were in complete atrioventricular block; three (10.8%) were asymptomatic without complete AV block, and in five (17.8%) the ablation was unsuccessful.

CONCLUSION

AV junction ablation with high energy shocks is safe and efficient in long-term follow-up.

Radiofrequency catheter ablation of incessant, medically resistant supraventricular tachycardia in infants and small children

OBJECTIVES

This study retrospectively evaluates initial experience with radiofrequency catheter ablation in a group of seven infants and small children with a history of incessant, medically resistant supraventricular tachycardia.

METHODS

Before attempted catheter ablation, all patients had had unsuccessful conventional medical therapy (with digoxin or propranolol, or both) and, in addition, each continued to have daily episodes of supraventricular tachycardia while taking amiodarone or a class IC antiarrhythmic agent alone or in combination. The average patient age was 10 months (range 1 to 27) and the average patient weight was 6 kg (range 3 to 13). Electrophysiologic diagnosis included reentrant supraventricular tachycardia in six patients and atrial ectopic tachycardia in one patient.

RESULTS

These seven patients underwent a total of nine catheter ablation procedures. The atrial approach to ablation was employed in eight of the nine procedures. Overall, radiofrequency catheter ablation was totally successful in five of the seven patients, partially successful in one patient and unsuccessful in the remaining patient. The combination of radiofrequency catheter ablation and surgical ablation was successful in controlling tachycardia in all patients; with at least 5 months of follow-up study, no patient has had a recurrence of supraventricular tachycardia or reappearance of a delta wave.

CONCLUSIONS

Surgical ablation of arrhythmogenic substrates in the pediatric age group, although rarely indicated, has been found in the past to be safe and effective. Our initial experience with radiofrequency catheter ablation in infants and small children demonstrates that this procedure is a promising nonpharmacologic therapeutic alternative to surgical ablation.

Effect of normothermic blood cardioplegia on postoperative conduction abnormalities and supraventricular arrhythmias

BACKGROUND

Conduction defects and supraventricular tachycardia (SVT) are common after myocardial revascularization using current methods of cold hyperkalemic blood or crystalloid cardioplegia. The current retrospective study was undertaken to assess the influence of normothermic blood cardioplegia on conduction defects and SVT.

METHODS AND RESULTS

The initial 92 patients underwent cardiopulmonary bypass (CPB) at 28 degrees C and blood cardioplegia at 6-8 degrees C. The subsequent 120 patients underwent CPB and blood cardioplegia at 37 degrees C. In all patients, cardioplegia was initially given by a combined antegrade/retrograde technique. The incidence of new postoperative conduction disturbances was significantly less in the normothermic group (p < 0.001): 27.5% versus 57.6% immediately after surgery; 9.2% versus 41.3% 1 day after surgery; 4.2% versus 32.6% 2 days after surgery; 1.7% versus 19.6% on hospital discharge; and 1.7% versus 17.4% on late follow-up. The incidence of supraventricular arrhythmias was not statistically different: 40.0% warm versus 42.4% cold. The groups were identical except that mean cross-clamp times were significantly longer (73.8 versus 60.1 minutes), mean number of grafts were significantly higher (3.7 versus 3.4), and mean cardioplegia volume was significantly greater (5,627 versus 3,710 ml) in the warm group (p < 0.05). In addition, the warm group had a higher incidence of prior transmural anterior myocardial infarctions (35% versus 9.8%, p < 0.001) and emergency operation (16.7% versus 6.5%, p < 0.05). Creatine kinase (CK) MB release was significantly less in the warm group immediately after operation (24.9 versus 60.9 units/l) and on POD1 (19.2 versus 46.5 units/l) (p < 0.001).

CONCLUSIONS

Normothermic cardioplegia is associated with a marked decrease in new and permanent conduction disturbances and postoperative CK-MB release. This suggests that a significant factor in the pathogenesis of conduction blocks is cold-related injury. Supraventricular arrhythmias were not affected by the type of cardioplegia given.

Electrocardiographically documented unnecessary, spontaneous shocks in 241 patients with implantable cardioverter defibrillators

The incidence and cause of electrocardiographically documented spontaneous implantable cardioverter defibrillator (ICD) discharges for a rhythm other than ventricular tachycardia (VT) or fibrillation (VF) (unnecessary shocks) were determined in 241 patients who underwent ICD implantation between March 1983 and November 1991. During follow-up of 24 +/- 20 months, 54 of 241 patients (22%) received a total of 132 unnecessary ICD shocks confirmed by Holter or telemetry monitoring or stored electrograms (Egs) from the ICD. The rhythm preceding these unnecessary ICD shocks was atrial fibrillation in 30 patients, sinus or supraventricular tachycardia (SVT) in 11 patients, antitachycardia pacing triggered by atrial fibrillation or SVT resulting in VT in 5 patients, nonsustained VT in 3 patients, and normal sinus or pacemaker rhythm in 10 patients. Unnecessary ICD discharges occurred most frequently during the first week after implantation or generator replacement (18 of 54 patients [33%]). Unnecessary ICD discharges could be documented more often by stored Egs in patients with devices with Eg storage capability (Ventritex Cadence, 19 of 54 patients [35%]) than by Holter or telemetry monitoring in patients with devices without Egs storage capabilities (34 of 193 patients [18%], P < 0.01), despite a shorter mean follow-up duration of 14 +/- 9 months versus 26 +/- 21 months, respectively. Only six of 54 patients (11%) in whom unnecessary ICD discharges occurred had recurrent unnecessary shocks during 22 +/- 20 months of follow-up after treatment directed at the cause of the first episode or device reprogramming to preclude non-VT rhythm detection.(ABSTRACT TRUNCATED AT 250 WORDS)

The significance of myocardial ischaemia and verapamil treatment on the prevalence of supraventricular tachyarrhythmias in patients recovering from acute myocardial infarction. Danish Study Group on Verapamil in Myocardial Infarction

Twenty-four hour Holter monitoring and symptom-limited exercise testing were carried out prior to discharge in 157 patients recovering from acute myocardial infarction. Supraventricular arrhythmias (SVT) during Holter monitoring were recorded in 15%, and ST segment depression during exercise in 27%. No association between exercise-provoked ischaemia and SVT was found in the late hospital phase of myocardial infarction. After the tests, patients were double-blindly randomized to treatment with verapamil 120 mg t.i.d. or placebo. One month after randomization 24 h Holter monitoring was repeated in 125 patients (verapamil = 63, placebo = 62). At one month a significantly increased incidence of SVT was found in the placebo group (25%) compared to the verapamil-treated patients (9%) (P = 0.04). The increased prevalence in the placebo group was mainly due to an increased incidence of SVT in patients with exercise-induced ischaemia (P = 0.03). This increment was blurred in the verapamil group. In conclusion, the prevalence of SVT increases during the first month after myocardial infarction. The increase is most pronounced in patients with residual myocardial ischaemia and seemed to be prevented by treatment with verapamil.

Long-term prognostic significance of ambulatory electrocardiographic findings in apparently healthy subjects greater than or equal to 60 years of age

To determine the long-term prognostic significance of frequent or complex ectopic beats and ST-segment changes on 24-hour ambulatory electrocardiogram (ECG) in apparently healthy older subjects, 98 volunteers were followed up from the Baltimore Longitudinal Study of Aging who were 60 to 85 years old and free of cardiac disease by history, physical examination and maximal treadmill testing at the time of ambulatory ECG between 1978 and 1980. Over a mean follow-up period of 10 years, coronary events developed in 14 subjects: angina pectoris in 7, nonfatal myocardial infarction in 3 and sudden cardiac death in 4. The incidence of coronary events did not differ significantly between subjects who developed the following arrhythmias and those who did not, respectively: greater than or equal to 30 supraventricular ectopic beats in any hour, 18 vs 13%; greater than or equal to 100 supraventricular ectopic beats in 24 hours, 20 vs 12%; paroxysmal atrial tachycardia, 15 vs 14%; greater than or equal to 30 ventricular ectopic complexes (VECs) in any hour, 17 vs 14%; greater than or equal to 100 VECs in 24 hours, 18 vs 14%; or repetitive VECs, 20 vs 13%. The mean 24-hour heart rate (75 +/- 8 vs 72 +/- 9 beats/min) as well as the maximal (116 +/- 20 vs 111 +/- 18 beats/min) and minimal (51 +/- 6 vs 53 +/- 7 beats/min) heart rate also did not differ between the coronary event and non-event groups.(ABSTRACT TRUNCATED AT 250 WORDS)

[The emergency treatment of supraventricular tachyarrhythmias: the efficacy and safety of intravenous propafenone]

One hundred patients, admitted to the Emergency Unit for paroxysmal supraventricular tachycardia (SVT) with 1:1 AV conduction, atrial fibrillation (af) and flutter (AF) of recent onset (less than 72 hours) were treated with intravenous propafenone (P). The drug was administered at the dose of 70 mg over 5 min, repeated after 10 min if sinus rhythm (SR) was not restored and eventually followed by continuous infusion (0.35-0.50 mg/min) until conversion to SR or during the next 48 hours. Exclusion criteria were ventricular rate < 100/min, R-R intervals > 1 s, clinical signs of heart failure or asthma. Termination of SVT within 30 min was obtained in 94% of the patients, while reversion to SR occurred in 79% with af and in 55% with AF. For af and AF conversion was achieved within 30 min in 49% of overall responders (R), between 30 min and 6 hours in 27% and between 6 hours and 48 hours in 24%. The efficacy of P was significantly influenced by the duration of arrhythmia and left atrial size, measured by 2D-echocardiography. On the contrary, no difference was observed between R and non-R in mean age and in the percentage of primary or relapsing arrhythmias. Adverse effects were encountered in 7 patients: in 1 case worsened arrhythmia and in 6 patients, with long-lasting arrhythmias, congestive heart failure. Neither conduction disturbance nor extra-cardiac complications occurred. In conclusion, P provides effective and safe treatment for paroxysmal atrial tachyarrhythmias, so that it can be considered among the drugs of first choice even in non-intensive care units.

Pharmacologic treatment of supraventricular tachycardia: the German experience

Tachyarrhythmias that originate above the bifurcation of the bundle of His or in tissue proximal to it are classified as supraventricular tachyarrhythmias (SVTs). Primary treatment of SVT tries to influence the underlying disease. Symptomatic therapy is subdivided into drug therapy, electrotherapeutic tools (e.g., antitachycardia pacemakers, catheter ablation), and antiarrhythmic surgery. Antiarrhythmic agents that slow conduction and suppress premature beats are efficient for emergency and long-term treatment of SVTs. We evaluated some of the most relevant antiarrhythmic drugs in SVT, including propafenone, diprafenone, cibenzoline, sotalol, and diltiazem; in addition, usage and efficacy of quinidine/verapamil, disopyramide, amiodarone, ajmaline, adenosine, and flecainide are summarized. In 1990, the case load of supraventricular arrhythmias per physician in Germany was more than 30 patients seen per month. About 50% of them were treated with drug therapy; i.e., approximately 17 patients were treated with antiarrhythmic drugs per month per physician for supraventricular arrhythmias. The most important antiarrhythmic agents used in Germany are propafenone (40%), combination of quinidine and verapamil (23%), sotalol (12%), disopyramide (6%), flecainide (6%), and other (13%).

Long-term follow-up of patients with inducible supraventricular tachycardia treated with flecainide or propafenone: therapy guided by transesophageal electropharmacologic testing

We report our experience with flecainide and propafenone therapy for inducible supraventricular tachycardias and paroxysmal supraventricular tachycardias due to atrioventricular (AV) nodal reentry or the Wolff-Parkinson-White syndrome. We performed an electropharmacologic test (ET) that consisted of first inducing a clinical arrhythmia by transesophageal atrial pacing (TAP) protocol. This was followed by intravenous drug administration and TAP reevaluation, either after acute intravenous administration or in oral steady-state. We used ET with flecainide and/or propafenone to study 2 groups of patients at least 3 years before the long-term clinical observation period. The first group was comprised of 58 patients with reciprocating tachycardias--due to AV node reentry in 17 (29.3%) and anomalous pathway in 41 (70.7%). Twelve (29.3%) of the latter had reciprocating tachycardias, 15 (36.6%) had atrial fibrillation, and 14 (34.2%) had both arrhythmias. During ET, flecainide was administered to 42 patients, and the ET was considered positive in 28 (66.7%). Propafenone was administered to 32 patients, with positive results in 15 (46.9%). In 15 patients, both flecainide and propafenone were tested, 8 receiving flecainide after a negative ET with propafenone, and 7 receiving propafenone after a negative ET with flecainide. In the first group, the ET was positive in 7 (87.5%), and in the second group, it was positive in 3 (42.9%). In a follow-up of 40.1 +/- 11 months, 38 (65.5%) patients had positive outcomes, 5 (8.6%) had to stop receiving the drugs because of side effects, 3 (5.2%) stopped because of inefficacy, and 12 (20.7%) dropped out.(ABSTRACT TRUNCATED AT 250 WORDS)

Correlation of symptoms with occurrence of paroxysmal supraventricular tachycardia or atrial fibrillation: a transtelephonic monitoring study. The Flecainide Supraventricular Tachycardia Study Group

The purpose of this study was to determine whether symptoms recorded at the time of transtelephonic ECG monitoring (TTEM) correlate with attacks of paroxysmal supraventricular tachycardia (PSVT) or paroxysmal atrial fibrillation (PAF). We studied 113 patients with these arrhythmias who made a total of 3319 TTEM calls during their participation in double-blind, placebo-controlled, crossover, multicenter trials of flecainide therapy. Among 49 patients with PSVT, 62.7% of symptomatic calls were associated with ECG-documented PSVT as compared with 6.8% of asymptomatic calls (p less than 0.001). Similarly, among 69 patients with PAF, 69% of symptomatic calls were associated with ECG-documented PAF compared with 10.6% of asymptomatic calls (p less than 0.001). Both in patients with PSVT and PAF, an attack of PSVT or PAF could be documented by ECG in more than 70% of the calls when patients complained of tachycardia, increased sweating, or dyspnea. The sensitivity of a symptomatic call was 91% for PSVT and 89% for PAF, and it was not influenced by flecainide therapy. However, flecainide therapy was associated with a decrease in the positive predictive value of symptomatic TTEM calls and an increase in false positive TTEM transmissions. We conclude that in patients with symptomatic PSVT or PAF, there is a temporal relationship between symptoms and the occurrence of ECG-documented attacks of PSVT or PAF. However, sole reliance should not be placed on the presence or absence of symptoms as a measure of drug failure or efficacy, and it is important to document the cardiac rhythm by TTEM at the time symptoms are recorded.

The incidence of atrial arrhythmias during inferior wall myocardial infarction with and without right ventricular involvement

The atrial arrhythmia profile during inferior wall acute myocardial infarction (AMI) has not been systematically examined with respect to right ventricular (RV) involvement. To this end, 62 consecutive patients with first inferior wall AMI and no other conditions known to increase susceptibility for rhythm disturbances were studied by 24-hour Holter monitoring during the first and tenth day of infarction. Based on radionuclear ventriculography performed on day 2 of infarction, patients were allocated to two groups: group A--36 patients (58%) with right ventricular ejection fraction (RVEF) less than 40% (mean +/- SD, 31 +/- 6%) and group B--26 patients (42%) with normal (greater than 40%) RVEF (mean +/- SD, 47 +/- 5%). There were no significant differences between the two groups with respect to age, sex, or left ventricular (LV) function. In the group as a whole, ectopic activity in the different categories of atrial arrhythmias was significantly higher during the first day than on the tenth day of infarction. Comparing the two groups, 33 patients (92%) in group A had a mean hourly frequency of one or more atrial premature contractions (APCs) during the first day of infarction compared with 18 patients (69%) in group B (p less than 0.001). Atrial and supraventricular tachycardia were recorded more frequently in group A patients (16 of 36 [44%] versus 8 of 26 [31%]) as well as atrial fibrillation (AF) (7 of 36 [19%] versus 1 of 26 [4%]). Quantitative analysis showed a similar trend for a higher rate of ectopic events in group A patients. Ectopic activity was neither influenced by LVEF nor by age or sex.(ABSTRACT TRUNCATED AT 250 WORDS)

Perinatal supraventricular tachycardia

OBJECTIVE

To determine the incidence, therapy required and prognosis of perinatal supraventricular tachycardia (SVT).

DESIGN

Retrospective chart review of eight years.

SETTING

Tertiary level perinatal and pediatric centres in Halifax, Nova Scotia.

PATIENTS

All newborn infants who developed SVT either in utero or in the first 30 days of life.

RESULTS

SVT was present in 33 neonates, with a male:female ratio of 2.7:1 and an incidence of 1:4347. Fetal SVT was recorded in nine (group I) but these patients did not differ from those with postnatal SVT (group II) in birthweight, noncardiac illnesses and associated heart disease. Thirty-one of the babies (94%) received digoxin and eight (24%) also required propranolol. All were asymptomatic after 48 h. One late death occurred due to renal failure unrelated to the dysrhythmia. No major congenital heart disease was found in either group. Follow-up over 44 months revealed four late relapses requiring prolonged therapy.

CONCLUSIONS

Perinatal SVT is a common disorder in a tertiary centre and may represent a transient adaptation phenomenon. It is usually benign, easily treated and rarely associated with major congenital heart disease.

Analysis of local electrogram characteristics correlated with successful radiofrequency catheter ablation of accessory atrioventricular pathways

Due to the limited myocardial lesions produced by radiofrequency current, the ablation of accessory pathways (AP) requires precise localization of such connections. The purpose of this study was to ascertain which characteristic(s) of the local bipolar electrogram, recorded from the ablation and adjacent electrode immediately prior to the application of radiofrequency current, correlated with precision in localization adequate to permit AP ablation. Signal analysis was performed for 326 sets of electrograms preceding the attempted ablation of 107 APs in 100 consecutive patients. For 80 antegrade APs, the following variables were evaluated: (1) the presence or absence of an AP potential; (2) the local atrial-AP interval; (3) the local atrioventricular (AV) interval; and (4) the relationship between the onset of local ventricular depolarization and onset of delta wave of the surface electrocardiogram. For the 27 concealed APs, the following characteristics were evaluated: (1) the presence or absence of an AP potential; and (2) the local VA interval during reciprocating tachycardia or ventricular pacing.

RESULTS

Antegrade APs: By statistical analysis, the best correlate of successful ablation of an antegrade AP was a local AV interval less than or equal to 40 msec (positive predictive value = 94%; 95% confidence intervals [CI] = 81%-100%). Local AV intervals less than or equal to 50 msec preceded 88% of successful AP ablations, compared to only 8% of failed radiofrequency current applications. The positive predictive value of the other variables were: presence of an AP potential: 35% (95% CI = 27%-40%); local atrial-AP intervals less than or equal to 40 msec: 54% (95% CI = 43%-66%); and local ventricular depolarization preceding onset of the delta wave 43% (95% CI = 34%-52%). For concealed APs, the positive predictive value of a VA interval less than 60 msec was 71% (95% CI = 48%-88%); the positive predictive value for the presence of an AP potential was 58% (95% CI = 32%-81%).

CONCLUSIONS

No single electrogram characteristic had a positive predictive value and a sensitivity greater than 90% for AP localization adequate for radiofrequency current ablation. For antegrade APs, the best correlate of adequate localization was a local AV interval less than or equal to 40 msec; as a corollary, radiofrequency current applications at sites where the local AV was greater than 60 msec, were unlikely to be effective. Objective criteria for the localization of concealed APs were less certain. Electrogram analysis, as a guide to AP localization and ablation, requires careful analysis of multiple variables, with analysis of the local AV interval a salient objective factor.