Paroxysmal Junctional Tachycardia Research Articles

PEDS11: Use of the CardioMEMSTM HF System in Pediatric Patients for Heart Failure Management

Background: The CardioMEMSTM HF system has been successfully used in adults for management of heart failure. Reports of use in pediatric patients are rare. In this case series, we aim to describe the novel use of this device in a large academic pediatric center. Methods: Retrospective, single center, descriptive case-series. Results: At time of abstract completion, our center has successfully implanted the CardioMEMSTM HF systems in four patients. The age at implantation ranged from 11 to 17 years, weight at implantation ranged from 27-73 kg. Vascular access for implantation was via a femoral vein in all patients. Three were implanted into the left lower pulmonary artery (PA) and one was implanted into the left pulmonary artery. The PA size ranged from 8.5-13.8 mm. There were no adverse events with implantation. The PA pressures reported by the device ranged from 14-20 mmHg and correlated with invasive monitoring. The pulmonary vascular resistance ranged from 2.3-8.7 iWu. Patient #1 had a diagnosis of Shone’s complex, and developed left ventricular diastolic dysfunction and resultant pulmonary artery hypertension (PAH). She was supported with a Berlin LVAD and subsequently underwent cardiac transplantation. Patient #2 had restrictive cardiomyopathy and paroxysmal junctional tachycardia with difficult to manage fluid status. This patient ultimately underwent cardiac transplant. Patient #3 had congenital aortic valve stenosis with concern of left atrial hypertension and ultimately underwent transplantation. Patient #4 had chemotherapy induced dilated cardiomyopathy and underwent Heartmate III LVAD implantation and is currently requiring milrinone for ongoing heart failure management. In all cases the CardioMEMSTM HF was successfully implanted and gave valuable diagnostic information in the management of PAH, fluid management and heart failure. Conclusions: This single center case series describes the early successful use of CardioMEMSTM HF system to aid management of PAH, fluid management and heart failure in a diverse pediatric population.

Lyme carditis presenting as paroxysmal junctional tachycardia and complete atrioventricular block in an adolescent

We describe a case of a previously healthy adolescent who presented with junctional tachycardia and complete atrioventricular (AV) block due to Lyme carditis. The simultaneous presence of these findings suggested significant inflammation of the AV junction. Junctional tachycardia, particularly if seen in a patient with conduction abnormalities and potential tick exposure, should increase suspicion for Lyme carditis.

Comparaison des sujets ayant des tachycardies jonctionnelles paroxystiques et des syncopes avec des sujets sans syncopes

Introduction The purpose of the study was to determine the possible mechanisms of presyncope in patients who have paroxysmal junctional tachycardias (PJT) and a normal surface ECG between tachycardias. Methods Among 419 patients consecutively recruited for PJT, aged from 10 to 88 years (47±19), 78 of them had presented at least one syncope; they had a normal ECG in sinus rhythm. Transesophageal programmed atrial stimulation was performed using one and two atrial extrastimuli delivered in control state and if necessary after infusion of 20–30 μg of isoproterenol; arterial blood pressure was monitored; vagal maneuvers and tilt test ( n = 25) were performed; echocardiogram was systematic. Results Age, sex, method of induction, tachycardia mechanism and the mean heart rate in tachycardia were similar in patients with and without syncope. Syncope was related to a vagal reaction induced by the PJT in 31 patients, to a fast rate during PJT in 15 patients, to a sinus node dysfunction in six patients, to a coronary ischemia in five patients, to a tetany induced by PJT in three patients, to an advanced age in three patients, to multiple causes in three patients and remained unexplained in eight patients. Radiofrequency ablation of reentrant circuit, performed in 28 patients, suppressed syncope in 26 of them. Conclusion Presyncope or syncope occurred in 18% of patients who had a history of paroxysmal junctional tachycardia. Several mechanisms were implicated; the most frequent causes were coronary ischemia or sick sinus syndrome in old patients, vasovagal reaction or fast rate in tachycardia or tetany in patients of all ages.

Clinical characteristics and management of paroxysmal junctional tachycardia in the elderly

The proportion of elderly subjects is in progress. While atrial fibrillation is the most frequent arrhythmia after the age of 70 years, other tachycardias also occur in the elderly. The aim of this study is to assess the clinical and electrophysiological characteristics of paroxysmal junctional tachycardia (PJT) in patients older than 70 years. Eight hundred sixteen patients aged from 8 to 93 years have been consecutively recruited for PJT. Among them, 141 (17%) were older than 70 years. The clinical, electro-physiology and therapeutic data were studied. Forty-eight men and 93 women with an age range from 70 to 93 years (mean 76+/-5) were admitted for recurrent PJT. They were associated to cardiac decompensation in 10 cases, syncope in 26 cases, acute coronary syndrome in 14 cases and unexplained acute vascular event in 5 cases. The electro-physiological mechanism of the PJT was similar to the younger patients with a majority of nodal reentrant tachycardia (73%). Atypical nodal tachycardias were more frequent than in the youth (15 versus 4%). PJT ablation was indicated more frequently in elderly patients than in younger patients (79 versus 57%), but complications (7% versus 2.5%) and failures, especially related to atrial fibrillation induction (19% versus 5%) were more frequent in elderly patients. Junctional tachycardias are not rare in the elderly and should not be missed. A cautious medical treatment can be impeded by the presence of conduction troubles or comorbidities. If this approach is not efficacious, these subjects might take benefit from curative ablation, with still a 10% failure rate.

Intérêt respectif de deux techniques d'étude électrophysiologique chez un sujet à cœur apparemment sain

Electrophysiologic study (EPS) frequently is required to assess the prognosis of asymptomatic Wolff-Parkinson-White syndrome (WPW) or to prove the nature of no documented tachycardia. EPS usually is performed by intracardiac route and hospitalization is required. Similar data are given by an EPS performed by oesophageal route during a consultation. The purpose of the study was to evaluate the cost of both techniques in France. Transesophageal EPS was performed during a consultation in 100 patients with asymptomatic WPW syndrome and 100 patients with no heart disease, complaining of no documented tachycardias with abrupt beginning and end, suggesting a paroxysmal junctional re-entrant tachycardia (PJRT). The cost of transesophageal study including isoproterenol infusion is 127.75 euros. The cost of intracardiac EPS is at least 1460 euros, cost of hospitalization during only one day. Results In patients with WPW syndrome, 15 had a potentially malignant form with the induction of a tachycardia conducted through the accessory pathway at a high rate (> 240/min in control state, > 300/min with isoproterenol); radiofrequency catheter ablation was indicated in a second time. In the group with no documented tachycardia, PJRT was induced in 30 patients and indication of ablation was discussed. In other 155 patients with either a benign form of WPW syndrome or with a tachycardia unrelated to a PJRT, hospitalization was not required; in these patients, intracardiac study performed during one day of hospitalization would have costed 226,300 Euros. The cost for the esophageal EPS and a similar diagnosis was 19,801 Euros, with a save money of 206,499 Euros. In 45 patients in whom hospitalization was indicated in a second time to perform catheter ablation of the arrhythmia, the cost related to esophageal EPS was 5749 Euros. In the total group, considering the final diagnosis and the need of hospitalization in 45 patients, the save money related to the use of esophageal EPS was 206,499 E–5749 E = 200,750 euros. Conclusions We should take into account the cost studies, when various techniques could be used for a similar diagnosis. There are important differences in the cost of diagnostic methods and it is easy to decrease this cost.

Atrial Stretch in Patients with Paroxysmal Junctional Tachycardias and Atrial Fibrillation but Structurally Normal Heart

to comparatively assess echographic indicators of atrial dilatation and decremental intra and interatrial and conduction in patients (pts) presenting junctional reentrant tachycardias (JT) with or without paroxysmal atrial fibrillation (pAF). 58 pts without structural heart disease, referred to electrophysiological study which underwent ablation for JT were studied; 26 pts aged 41±10 years with pAF episodes/ inducible AF, were compared to 32 control-matched JT pts aged 39±12 years. Parameters: left atrial dimensions (LAd = M-mode, parasternal, LAt and LAl are measurements of short and long-axis apical four chamber view), surface (LAs), volume (LAv using ellipse formula), right atrial surface (RAs), total atrial surface (TAs = LAs+RAs). Decremental index (DI) was calculated as maximum percent prolongation of interatrial conduction time (iaCT) during S2 and S3 delivery. there was no difference between the 2 groups concerning baseline iaCT (59±21 ms vs 53±18 ms p = 0.08), LAd (p = 0.08) and LAt (p = 0.09) while the following parameters were significantly higher in pAF pts: LAl: 5.0±0.5 vs 4.5±0.3cm, (p = 0.001); LAs: 19.6±5.7 vs 16.3±2.1cm2, (p = 0.001); TAs: 35.6±6.9 vs 27.6±5.1 cm2 (p = 0.0001); LAv: 46.6±10.4 vs 37.2±9.3 ml, (p = 0.0001); DI: 41±17% vs 24±14% (p = 0.001). In pAF group, atrial fragmentation and atrial double potentials were recorded in 23 pts. No control pts had this evidence. this study supports the role of atrial stretch in the genesis of AF in pts with junctional tachycardias. Further studies need to investigate the relation between burden of tachycardia and atrial stretch in a larger population.

Utility of transesophageal atrial pacing in the diagnostic evaluation of patients with unexplained syncope associated or not with palpitations

Background: Noninvasive studies are often negative in patients with syncope, normal surface ECG and without heart disease. The purpose of the study was to determine the diagnostic impact of an esophageal electrophysiological study performed during a consultation. Methods: A total of 154 patients aged from 16 to 87 years were consecutively recruited for unexplained syncope; they had a normal ECG in sinus rhythm, no documented arrhythmia and no patent heart disease. Half of them complained of palpitations. Electrophysiologic study was performed during a consultation by transesophageal route: rate of 2nd d AV block occurrence during atrial pacing and sinus node recovery time were determined; programmed atrial stimulation using one and two atrial extrastimuli were delivered in control state and then after infusion of 0.02–1 μg/min of isoproterenol; arterial blood pressure was monitored. Results: (1) Electrophysiologic study was positive in 107 patients (69%); (2) sinus node dysfunction was noted in 9 patients (6%); (3) atrioventricular conduction disturbances were noted in 2 patients (1%); (4) vasovagal reaction which associated a junctional bradycardia and a fall of arterial blood pressure and which reproduced spontaneous symptoms was provoked by isoproterenol infusion in 21 patients (14%); (5) sustained atrial fibrillation was induced in 23 patients (15%); and (6) paroxysmal junctional tachycardia was induced in 52 patients (34%). Patients with negative study were younger (44±21.5 years) than those with sinus node dysfunction or atrial fibrillation (71±9 and 63±14 years, respectively). The treatment was guided by these data: patients with inducible atrial fibrillation were treated by antiarrhythmic drugs and those with inducible paroxysmal junctional tachycardia by the radiofrequency ablation of reentrant circuit. Syncope disappeared in all patients but 2. Conclusion: Esophageal electrophysiologic study performed during a consultation was a safe, rapid and economic means to detect an arrhythmia (sinus node dysfunction or supraventricular tachycardia) in patients with dizziness/syncope and palpitations in half cases. Supraventricular tachycardia was clearly an underestimated cause of syncope in this population.

1072-211 Independent predictive accuracy of classical electrocardiographic criteria in the diagnosis of paroxysmal junctional tachycardias in patients without preexcitation

1072-211 Independent predictive accuracy of classical electrocardiographic criteria in the diagnosis of paroxysmal junctional tachycardias in patients without preexcitation

1857 Is anticoagulation required in patients with unexplained cerebrovascular accident and paroxysmal junctional tachycardia?

1857 Is anticoagulation required in patients with unexplained cerebrovascular accident and paroxysmal junctional tachycardia?

P1558 Independent predictive accuracy of classical electrocardiographic criteria in the diagnosis of paroxysmal junctional tachycardias in patients without preexcitation

P1558 Independent predictive accuracy of classical electrocardiographic criteria in the diagnosis of paroxysmal junctional tachycardias in patients without preexcitation

Influence of Age on the Potential Risk of Sudden Death in Asymptomatic Wolff‐Parkinson‐White Syndrome

Sudden death might be the first event in patients with asymptomatic WPW. The purpose of the study was to know if the age of the patient modifies the electrophysiological characteristics of asymptomatic WPW. Transesophageal stimulation was performed on 92 asymptomatic WPW patients from the following age groups: 10-69 years (n = 14), 20-29 years (n = 33), 30-39 years (n = 15), 40-49 years (n = 17), and 50-69 years (n = 13). The procedure consisted of atrial pacing up to the second AV block, programmed atrial stimulation using one and two extrastimuli delivered on two driven rhythms in the control state, and after infusion of isoproterenol. In thefive age groups, paroxysmal junctional tachycardia occurred, respectively, in 1 (7%), 1 (3%), 2 (13%), 2 (12%) patients, and not at all in the oldest group. AF > 1 minute occurred, respectively, in 3 (21%), 9 (27%), 5 (33%), 3 (18%), and 4 (31%) patients. The dangerous form of WPW (rapid conduction in the Kent bundle > 240/min in the control state or > 300/min after isoproterenol + AF induction) occurred, respectively, in 3 (21%), 9 (27%), 4 (27%), 1 (6%), and 3 (23%) patients. In conclusion, electrophysiological data of asymptomatic WPW are not modified by age of the patient. Elderly patients remain at risk of a dangerous form of WPW; systematic evaluation of WPWis recommended in patients with an active life independent of age.

Incidence and mechanism of presyncope and/or syncope associated with paroxysmal junctional tachycardia

The objectives of this study were to: (1) define the incidence of presyncope and/or syncope in patients with paroxysmal junctional tachycardias, (2) determine their causes, and (3) determine the outcome of symptoms. Syncope is a frequent problem and is often caused by paroxysmal tachycardia. The mechanism of hemodynamic instability is unknown. The population study consisted of 281 patients, consecutively recruited because they had paroxysmal tachycardia and a sinus rhythm on a normal electrocardiogram. Fifty-two patients (group I) had presyncope and/or syncope associated with tachycardia. The remaining patients (group II) had no loss of consciousness. Transesophageal programmed atrial stimulation used 1 and 2 atrial extrastimuli, delivered in a control state, and if necessary, after infusion of 20 to 30 μg of isoproterenol. Arterial blood pressure was monitored. Vagal maneuvers and echocardiogram were performed in all patients. Paroxysmal tachycardia was induced in 51 group I patients and 227 group II patients. Comparisons of groups I and II revealed that age (50 ± 21 vs 49 ± 17 years), presence of heart disease (10% vs 10%), mechanism of tachycardia with a predominance of atrioventricular nodal reentrant tachycardia (70.5% vs 76%), and rate of tachycardia (196 ± 42 vs 189 ± 37 beats/min) did not differ between the groups. However, there were differences in both groups with regard to significantly higher incidences of positive vasovagal maneuvers (35% vs 4%, p <0.01), isoproterenol infusion required to induce tachycardia (55% vs 17%, p <0.001), and vasovagal reaction at the end of tachycardia (41% vs 4%, p <0.05). Thirty-seven group I patients underwent radiofrequency ablation of the reentrant circuit, which suppressed presyncope and/or syncope in 36 of the 37 patients. Thus, presyncope and/or syncope frequently complicated the history of patients with paroxysmal junctional tachycardia (18.5%). Several mechanisms are implicated, but vasovagal reaction was the most frequent cause. Treatment of the tachycardia typically suppressed presyncope and/or syncope.

Influence of age on the electrophysiological mechanism of paroxysmal supraventricular tachycardias

The purpose of this study was to evaluate the influence of age on the mechanism of paroxysmal supraventricular tachycardia (PSVT). Previous studies have shown age and sex differences between certain arrhythmias and especially changes in electrophysiological characteristics of Wolff–Parkinson–White syndrome. Four hundred and eighty five patients aged 9–86 years, with PSVT and without Wolff–Parkinson–White syndrome in sinus rhythm, were studied. The esophageal or intracardiac electrophysiological study used a standardized atrial pacing protocol. Paroxysmal junctional tachycardia was induced in 475 patients. The mechanism of tachycardia was not influenced by age and atrioventricular nodal reentrant tachycardia (AVNRT) was found as the main cause of PSVT in all ranges of age. Atrioventricular reentrant tachycardia (AVRT) using a concealed accessory pathway (AP) had a similar incidence from youth to elderly. The ratio male/female (M/F) and the inducibility of other arrhythmias (atrial flutter/fibrillation) (AF/AFl) were also found to be similar in all ranges of age. The age of the patients did not influence the mechanism of the tachycardia. Most of PVST were related to a AV nodal reentrant tachycardia. Concealed accessory pathway was identified with a similar incidence in young and old patients.

Transformation d'un syndrome de Wolff–Parkinson–White asymptomatique en forme symptomatique par une ablation du faisceau de Kent

We report the case of an asymptomatic young man, 19 years old, who had a Wolff–Parkinson–White syndrome. A form at risk of potentially severe arrhythmias was detected by the electrophysiological study. The Kent bundle radiofrequency ablation was performed with success. However the patient developed few weeks after, spontaneous paroxysmal junctional tachycardias. Such report indicates that we should remain careful in asymptomatic patients.

Treatable cardiomyopathies.

Cardiomyopathy is defined as primary myocardial dysfunction which is not due to hypertensive, valvular, congenital, coronary or pulmonary vascular disease. This term usually denotes a dismal prognosis short of cardiac transplantation. However, several organic diseases of the heart can result in right or left ventricular dysfunction resulting in congestive heart failure and prompting the physician to label them as cardiomyopathy; the etiological factor is overlooked as it produces very subtle features. Therefore, before labelling any child as cardiomyopathic, all possible causes of ventricular dysfunction must be excluded by clinical and investigative means. The causes of "treatable cardiomyopathy" include mechanical factors as critical aortic stenosis and pulmonic stenosis, severe coarctation of aorta in an infant and aortaarteritis is an older child. Some of the persistent arrhythmias like atrial tachycardia, fibrillation, paroxysmal junctional re-entrant tachycardia are also known for causing ventricular dysfunction producing tachycardiomyopathy. Treatment of arrhythmia improves the ventricular function. Myocardial ischemia as a result of congenital coronary anomaly (commonest being anomalous origin of left coronary artery from pulmonary artery) can also present with a cardiomyopathy like picture. Early surgical correction is very rewarding. Finally, some of the metabolic conditions like creatinine and thiamine deficiency can also produce ventricular dilatation and dysfunction. In conclusion, the so called cardiomyopathy like picture can be produced because of several reasons and an attempt must be made to identify them.

Using the right drug: a treatment algorithm for regular supraventricular tachycardias.

Despite the recent advent of and the successful results from catheter ablation, pharmacological therapy is still used by most clinicians as the first line therapy in patients with regular supraventricular tachycardias. Before prescribing an antiarrhythmic agent, documentation of the arrhythmia using a 12-lead electrocardiogram (ECG) is necessary to identify the type of tachycardia. The ECG diagnosis is based on the presence and polarity of the P wave, the P to QRS relationship, the presence of QRS alternation and the effect of bundle branch block on tachycardia rate. Most regular supraventricular tachycardias use the atrioventricular node either passively, as in atrial tachycardias or flutter, or actively, as paroxysmal junctional tachycardias. The Sicilian Gambit approach attempted to introduce some rationale in the choice of an antiarrhythmic agent, taking into account tachycardia mechanism, by defining the critical components of the tachycardia and the vulnerable parameter, i.e. the component that may readily be affected by an appropriate antiarrhythmic agent. For this approach, an electrophysiological study is particularly useful. The most common regular paroxysmal supraventricular tachycardias include atrioventricular nodal re-entrant tachycardias and atrioventricular re-entrant tachycardias which use an overt or concealed accessory atrioventricular connection (Kent bundle) or atriofascicular connection (Mahaim). For acute termination of paroxysmal junctional tachycardia, intravenous adenosine is the drug of choice. For the prevention of the tachycardia attacks in atrioventricular nodal re-entrant tachycardia, the agents with a depressive effect on the antegrade slow pathway, such as calcium channel blockers or beta-blockers, are likely to be effective. If they fail, sodium channel blockers (propafenone or flecainide) may be indicated. In tachycardias involving accessory connections, agents that affect fast channel dependent tissue (propafenone, flecainide, cibenzoline, disopyramide or hydroquinidine) are effective. Potassium current blockers, such as sotalol or amiodarone, represent an alternative therapy. In atrial tachycardias, the use of propafenone, flecainide or sotalol constitute a logical choice. In drug-resistant cases, amiodarone is the most potent agent. Radiofrequency ablation of the slow atrioventricular nodal pathway, of an accessory connection or of an atrial focus, is indicated in drug-resistant or drug-intolerant patients and is increasingly offered as an alternative therapy.

Catheter ablation in competitive athletes: indication.

Some supraventricular tachyarrhythmias (SVT), particularly if paroxysmal and/or related to Wolff-Parkinson-White syndrome (WPW), may in some cases endanger an athlete's professional career due to hemodynamic consequences during athletic activity, which in some instances may be life-threatening. One must also take into account that in Italy the law makes antiarrhythmic drug treatment (AAD) incompatible with sport eligibility. For these reasons, the utilization of radiofrequency ablation (RFA) in athletes has different indications as opposed to the normal population, since the primary goal is "the eligibility of the athlete." In our study, we discuss the criteria for indication of RFA in athletes with SVT on the basis of the data obtained from our population of athletes, studied over a 20-year period, from 1974 to the 31st of December 1993. These athletes were evaluated for arrhythmic events, utilizing a standardized cardioarrhythmological protocol: 1,325 athletes (1,125 men, 200 women, mean age 20.7 years). One subgroup included 380 athletes with WPW (28.7%), 22 athletes with aborted sudden death (1.6%), 6 of whom had WPW, 13 athletes with sudden death (0.98%), and 2 of whom had WPW. Another subgroup was formed by 116 top level elite professional athletes (TLA) (mean age 22.9 years), of which 10 of 116 (8.6%) had WPW and 12 of 116 (10.3%) had paroxysmal SVT. The most important indications for RFA in athletes are represented by: WPW asymptomatic at risk, symptomatic during athletic activity, and/or requiring AAD treatment: paroxysmal junctional reentrant tachycardia: when this condition is disabling and related to exercise and therefore compromising an athlete's performance and sports career. Paroxysmal junctional reentrant tachycardia is easily reproduced via transesophageal atrial pacing (TAP) during exercise (bicycle ergometer), common in athletes but normally the recurrences are concentrated only during the period in which the athlete is engaged in sport. Rare indications for RFA are focal or reentry, permanent SVT, and particularly junctional reentrant tachycardia. For each individual athlete, we have to consider the possible side-effects of RFA, the possible recurrences with psychobiological traumatic consequences, the effective recovery period, and the natural history of the tachyarrhythmias, which frequently disappear after interruption of the sports career.

Automatic junctional tachycardia in an adult

We report an adult patient with junctional ectopic tachycardia, a condition which was initially described in infants, frequently in association with congenital defects. The patient had a rapid, irregular paroxysmal junctional tachycardia with a rate ranging from 160 to 220 beats/min, distinguishing it from the more common nonparoxysmal junctional tachycardia in which a slower heart rate is seen. The electrophysiological study performed during an episode of tachycardia demonstrated periods of atrioventricular dissociation and narrow QRS complexes as well as a junctional ectopic rhythm, which was suggested by a His deflection preceding each ventricular depolarization with a normal HV interval. Both the response to exercise and the results of atrial and ventricular stimulation suggested enhanced automaticity of a high junctional focus. Therapy combining procainamide, verapamil, and digitalis proved to be effective. Thus, junctional ectopic tachycardia can also occur in adults, probably due to enhancement of automaticity.

Comparison of adenosine and verapamil for termination of paroxysmal junctional tachycardia

The effects of intravenous adenosine and intravenous verapamil on paroxysmal functional tachycardia were compared in 20 patients undergoing invasive cardiac electrophysiologic study. In 13 patients the diagnosis was of a reentrant tachycardia using an extranodal accessory connection (atrioventricular [AV] reentrant tachycardia); 5 of these patients had overt preexcitation in sinus rhythm, 4 had concealed accessory connections and 4 had latent or intermittent preexcitation. In 7 patients the diagnosis was of an AV nodal reentrant tachycardia. Administration of adenosine resulted in termination of tachycardia in all 20 patients at a mean dose of 0.125 mg/kg (range 0.05 to 0.20). Although termination of tachycardia was frequently accompanied by atrial and ventricular premature complexes, no significant arrhythmias were observed after conversion. Administration of verapamil (0.145 mg/kg) resulted in termination of tachycardia in 19 of 20 patients but was followed by symptomatic arrhythmias in 2: preexcited atrial flutter in 1 patient and preexcited atrial tachycardia in another. Latent or intermittent preexcitation was unmasked in 4 of 4 patients immediately after termination of tachycardia by adenosine. Termination of tachycardia by verapamil revealed preexcitation in only 1 of these 4 patients. Analysis of results in terms of successful termination of tachycardia, absence of significant arrhythmias after conversion and unmasking of latent or intermittent preexcitation reveals that adenosine therapy was satisfactory in all 20 patients, whereas verapamil was satisfactory in only 14 of the 20 patients (p < 0.05). All 6 of the patients with unsatisfactory responses to verapamil had AV reentrant tachycardia. These results suggest that adenosine has particular advantages over verapamil as acute treatment for patients presenting with an AV reentrant tachycardia.

Isoprenaline as an aid to the induction of catecholamine dependent supraventricular tachycardias during programmed stimulation.

The effects of isoprenaline on the induction of supraventricular tachycardia by programmed stimulation were studied in 67 patients to see whether they correlated with spontaneous catecholamine mediated symptoms during exercise testing and Holter monitoring. Thirty seven control patients (group 1) did not have spontaneous arrhythmias either during exercise testing or Holter monitoring. Thirty patients (group 2) had documented exercise or stress related supraventricular tachycardias--that is paroxysmal junctional tachycardia (24) or atrial arrhythmia (6). Programmed electrical stimulation was performed before and during the infusion of isoprenaline. No group 1 patient developed sustained supraventricular tachycardia during isoprenaline infusion. In 21 patients with paroxysmal junctional tachycardia and all the patients with atrial arrhythmias electrical stimulation during isoprenaline infusion produced the same tachycardia that had been seen during exercise testing and Holter monitoring. Changes in electrophysiological variables and the concentrations of serum potassium were not associated with the induction of supraventricular tachycardia by isoprenaline. Infusion of isoprenaline safely facilitated the induction of supraventricular tachycardia by programmed stimulation in patients who had spontaneously occurring catecholamine mediated symptoms.