Diagnostic value of ventricular stimulation in patients with idiopathic dilated cardiomyopathy

To assess the response to programmed ventricular stimulation and the clinical outcome, we performed a prospective study in 103 patients with idiopathic dilated cardiomyopathy. The protocol used up to three extrastimuli delivered at two right ventricular sites during sinus rhythm and ventricular pacing at 100 and 150 beats/min and was repeated during infusion of 1 to 4 micrograms/min of isoproterenol. Sustained monomorphic ventricular tachycardia (VT) was induced in 8 of 11 patients with spontaneous sustained VT, in none of 35 patients without significant ventricular arrhythmias during Holter monitoring, and in 9 of 56 patients with salvos of ventricular premature beats. Isoproterenol infusion facilitated the induction of two episodes of sustained VT in patients with spontaneous sustained VT; however, in all but one of the remaining patients, induction of ventricular tachyarrhythmias was not impaired. During the follow-up period there were eight sudden deaths among patients who initially had syncope, inducible sustained VT, or both and three episodes of sustained VT in patients who initially had nonsustained VT but inducible sustained VT. Isoproterenol infusion can be used to safely facilitate induction of ventricular tachyarrhythmias in patients with dilated cardiomyopathy. The induction of sustained VT was associated with a poor prognosis.

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.

Organ dysfunction and muscular disability in myotonic dystrophy type 1

Myotonic dystrophy type 1 (DM1) is a multisystemic disorder characterized by muscle weakness and multiple organ impairment, especially the eyes, lung, and heart. We conducted the current study to analyze the prevalence and intercorrelation among these disorders and their respective relationships with muscular disability. We assessed medical history, anthropometric data, lung volumes, arterial and venous blood samples, surface 12-lead electrocardiogram, echocardiography, ophthalmologic examination, and muscular impairment rating scale (MIRS) in 106 patients (48 male and 58 female) with DM1, aged 43.7 ± 12.8 years. Obesity, hypertriglyceridemia, and diabetes were found in respectively 25.6%, 47.6%, and 17.1% of patients. Disabling cataract was found in 43.4%, and was independently predicted by age and MIRS. Restrictive lung disease was noted in 34%, and was predicted by MIRS, CTG repeat expansion, and body mass index. Conduction disorders were found in 30.2% of patients and were predicted by left ventricular ejection fraction, MIRS, and CTG repeat expansion.We found significant relationships between cataract, restrictive lung disease, and conduction disorders: patients with cataract and those with conduction disorders exhibited more severe restrictive lung disease than the other patients. Conversely, the relative risk of restrictive lung disease was 2.42 (1% confidence interval [CI], 1.06-5.51) in patients with cataract and 2.54 (1% CI, 1.26-5.07) in patients with conduction disorders. Multivariate analysis revealed that MIRS was the only independent predictor for conduction disorders and restrictive lung disease. MIRS ≥3 and MIRS ≥4 were the best simple cutoff values to predict, respectively, lung and cardiac involvements.To conclude, muscular disability, ophthalmologic, and cardiac and pulmonary involvement are strongly correlated. Particular attention should be given to these entities in patients with distal or proximal muscular weakness.

Value of esophageal pacing in evaluation of supraventricular tachycardia

Esophageal stimulation was performed in 40 patients who had spontaneous paroxysmal supraventricular tachycardias (SVTs). The purpose of this study was to look for the most sensitive stimulation protocol and criteria that would help to define the mechanism of reentry. In 20 patients (group I) atrial pacing up to second-degree atrioventricular block was performed under control conditions and isoproterenol, and SVT was induced in 14 patients (70%), 11 in the control state and 3 while receiving isoproterenol. In 20 patients (group II) atrial pacing and programmed atrial stimulation using 1 and 2 extrastimuli delivered at 2 cycle lengths (600 and 500 ms) was performed in the control state and while receiving isoproterenol. SVT was induced in all patients, in 13 patients in the control state and in 7 while receiving isoproterenol. Programmed stimulation always induced SVT and was the only method capable of tachycardia induction in 14 patients. The mechanism of SVT could be established in 91%. The measurement of the ventriculoatrial interval was the most useful sign to define the site of reentry. Occurrence of a bundle branch block helped to delineate the mechanism in 4 patients. When a positive P wave in V1 preceded the esophageal atrial electrocardiogram, it suggested that there was reentry through a left-sided accessory atrioventricular connection in 6 patients. SVT could always be induced by programmed atrial stimulation in the control state and under isoproterenol. The location of the P wave in V1 compared to the ventriculogram and the esophageal electrocardiogram helped to define the mechanism of tachycardia.

Electrophysiological characteristics of asymptomatic Wolff-Parkinson-White syndrome

Although most asymptomatic patients with the Wolff-Parkinson-White syndrome have a good prognosis, some die suddenly. Electrophysiological testing may identify patients at possible risk of sudden death. The mechanism of sudden death in these patients is believed to result from ventricular fibrillation due to atrial fibrillation with rapid anterograde conduction over the accessory pathway. Consequently, we performed electrophysiological studies in 40 asymptomatic patients with the Wolff-Parkinson-White syndrome. Certain electrophysiological properties clearly identified these patients: (1) in most patients sustained reciprocating tachycardia could not be induced and this explains the absence of symptoms of regular fast palpitations; (2) the incidence of inducible sustained atrial tachyarrhythmias (30%), of short RR intervals between pre-excited beats (20%) and of risk of sudden death (12.5%) was similar to the incidence in symptomatic patients with the Wolff-Parkinson-White syndrome and reciprocating tachycardia. Because of the ease with which transoesophageal study can be performed we think that the asymptomatic Wolff-Parkinson-White syndrome should be systematically evaluated so as to reassure patients with the benign form that they can lead a normal life and take part in sport and secondly to define the real prognosis of the patients whose characteristics suggests a risk of sudden death.

Differences in mechanisms and outcomes of syncope in patients with coronary disease or idiopathic left ventricular dysfunction as assessed by electrophysiologic testing

OBJECTIVES

This study evaluated the causes of syncope and the significance and differences in left ventricular (LV) dysfunction, coronary disease, and idiopathic dilated cardiomyopathy (DCM).

BACKGROUND

Risk stratification of and indications for an automated defibrillator could differ according to the cause of LV dysfunction.

METHODS

Electrophysiologic study, including atrial and ventricular programmed stimulation, was performed in 119 patients with coronary disease (group I) and 61 patients with DCM (group II) with an left ventricular ejection fraction (LVEF) <40% and syncope. Patients were followed from one to six years (mean 4 +/- 2 years).

RESULTS

Sustained monomorphic ventricular tachycardia (VT) was induced in 44 group I patients (37%) and 13 group II patients (21%); ventricular flutter (>270 beats/min) or ventricular fibrillation (VF) was induced in 24 group I patients (19%) and 9 group II patients (15%); and various other arrhythmias were identified. Syncope remained unexplained in 34 group I patients (30%) and 16 group II patients (27%). Prognosis depended on the heart disease: VT or VF induction was a predictive factor of mortality in coronary disease and identified a group with high cardiac mortality (46%), compared with patients with a negative study, who had a lower mortality (6%; p < 0.001) than in other studies. Cardiac mortality was only correlated with LVEF in DCM.

CONCLUSIONS

Various causes could explain syncope in 70% of patients with coronary disease and DCM, but differences were noted: VT was frequent in coronary disease with a bad prognosis, and ischemia could explain syncope; in DCM, different causes such as atrial tachycardia could be responsible for syncope, but the prognosis only depended on LVEF.

Induction of sustained ventricular tachycardia after surgical repair of tetralogy of Fallot

Between 1980 and 1996, 89 unselected consecutive patients with repaired tetralogy of Fallot (TOF) underwent examination, including a prospective right ventricular programmed stimulation with the same protocol (S1 S2, S3, S4). Age at surgery was 4.2 +/- 3.5 years and age at electrophysiologic study was 10.9 +/- 6.5 years. Follow-up since surgery was 14.4 +/- 4.8 years and patient follow-up after programmed stimulation was 7.8 +/- 4.2 years. The aim of this study was to evaluate the main predictors of the inducibility of a sustained monomorphic ventricular tachycardia (VT) and its significance to identify a group of patients at risk of sudden death: 21 (group A) had and 68 (group B) had no induced sustained VT. The induction of VT was related to older age at programmed stimulation, prolonged QRS duration, presence of complex ventricular arrhythmia, symptoms, right ventricular overload, and increased right ventricular systolic pressure. Predictors of induced VT selected by multivariate analysis were age at electrophysiologic study (p <0.0001), previous palliative shunts (p <0.001), right ventricular systolic pressure (p <0.007), and symptoms (p <0.005). Among group A patients, 4 had previous sustained VT before stimulation, and 1 had sustained VT only during follow-up after stimulation. No patients of group B had clinical sustained VT. Late mortality was low but similar between both groups. A negative electrophysiologic study may be helpful for the management of patients after surgical repair of TOF, but because the arrhythmic event rate is low, the findings of even a positive electrophysiologic study should be interpreted with caution.

Interest of non-invasive and semi-invasive testings in asymptomatic children with pre-excitation syndrome

AIMS

To determine the feasibility and the results of exercise testing (ET) and electrophysiological study (EPS) in outpatient asymptomatic children with a Wolff-Parkinson-White (WPW) syndrome.

METHODS AND RESULTS

Exercise testing and transesophageal EPS were performed in 55 outpatient asymptomatic children aged 6 to 19 years old (14 +/- 3) with WPW. Wolff-Parkinson-White persisted during maximal exercise. Isoproterenol was not required in five children younger than 10 years old, because they developed a catecholaminergic sinus tachycardia. Maximal rate conducted through accessory pathway (AP) was higher in children younger than 16 years old than in teenagers (P < 0.05). Atrioventricular re-entrant tachycardia (AVRT) was induced in six children; atrial fibrillation (AF) in 12 children. The induction of tachycardias and the dangerous forms (18%) were not influenced by age. After 5 +/- 1 years, one child, 12 year old with inducible rapid AF, had a sudden cardiac arrest; two children became symptomatic after ablation.

CONCLUSIONS

Transesophageal EPS was required to determine the prognosis of asymptomatic WPW in children. The maximal rate conducted in AP was higher in children younger than 16 years old than in teenagers; other data did not differ. AVRT was rare; 71% of children had no inducible arrhythmia and were authorized to resume physical activities.

Atrial flutter or fibrillation is the most frequent and life-threatening arrhythmia in myotonic dystrophy

BACKGROUND

Several arrhythmias were reported in myotonic dystrophy (MD).

OBJECTIVES

To evaluate the prevalence of atrial fibrillation (AF) and atrial flutter (AFL) in MD and the clinical consequences.

METHODS

One hundred sixty-one patients, mean age 41 ± 14 years, were referred for a type 1 MD. All patients were asymptomatic except four patients and followed during 5 ± 4 years. Electrocardiogram (ECG), echocardiography assessing left ventricular ejection fraction, and Holter monitoring were obtained and repeated.

RESULTS

Twenty-seven patients (17%) presented sustained (>1 hour) AF (n = 15) or AFL (n = 12); two of them presented syncope-related 1/1 AFL. In one of them, 16 years of age, cardiac defibrillator was implanted for a diagnosis of ventricular tachycardia, but the true diagnosis was established after inappropriate shocks. AFL ablation was performed in five patients, but four developed AF. The other seven patients with AFL developed AF. During the follow-up, 22 patients died (14%) from cardiac and respiratory failure; eight patients with AF/AFL died (30%) while only 14 without AF/AFL died (10%; P < 0.01). Univariate analysis indicated that age >40 years (death: 48 ± 14 vs 40 ± 8 in alive patients), abnormal ECG, and occurrence of AF/AFL were significant factors of death. At multivariate analysis, AF at ECG (odds ratio: 3.12) and age >40 (odds ratio: 3.14) were the sole independent variables predicting death.

CONCLUSIONS

AF and AFL were frequent in MD and increased mortality. AFL could present as 1/1 AFL with a poor tolerance and a risk of misdiagnosis despite frequent conduction disturbances. This arrhythmia could explain wide QRS tachycardia occurring in MD and interpreted as VT.

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 microg 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.

Predictors of atrial flutter with 1:1 conduction in patients treated with class I antiarrhythmic drugs for atrial tachyarrhythmias

OBJECTIVES

The purpose of the study was to look for the predictor factors of atrial proarrhythmic effects of class I antiarrhythmic drugs.

BACKGROUND

Class I antiarrhythmic drugs may induce or exacerbate cardiac arrhythmias. The predictors of ventricular proarrhythmia are known. The predictors of atrial flutter with 1:1 conduction are unknown.

METHODS

Clinical history, EGG, signal-averaged EGG (SAECG) and electrophysiologic study were analysed in 24 cases of 1:1 atrial flutter with class I AA drugs and in 100 control patients without history of 1:1 atrial flutter with class I AA drugs.

RESULTS

The ages of patients varied from 46 to 78 years. Underlying heart disease was present in nine patients. The surface EGG revealed the presence of a short PR interval (PR<0.13 ms), visible in leads V5, V6 in eight (35%) patients with normal P wave duration; in other patients with prolonged P wave duration, PR seemed normaL On SAECG recording, there was a pseudofusion between P wave and QRS complex. The electrophysiologic study revealed some signs indicating a rapid AV nodal conduction (short AH interval or rate of 2nd degree AV block at atrial pacing >200 beats/mm) in 19 of the 23 studied patients. All patients, except one, had at least one sign indicating a rapid AV nodal conduction (short PR and/or P wave-QRS complex continuity on SAECG). In the control group, seven patients (7%) had a short PR interval (P<0.01) and 11 (11%) had a pseudofusion between P wave and QRS complex on SAECG (P<0.001). The P wave-QRS complex pseudofusion on SAECG had a sensitivity of 100% and a specificity of 89% for the prediction of an atrial proarrhythmic effect with class I antiarrhythmic drug.

CONCLUSION

We recommend avoiding class I AA drugs in patients with a short PR interval on surface EGG and to record SAECG in those with apparently normal PR interval to detect a continuity between P wave and QRS complex, which could indicate a rapid AV nodal conduction, predisposing to 1:1 atrial flutter with the drug.

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.

The signal-averaged electrocardiogram is of limited value in patients with bundle branch block and dilated cardiomyopathy in predicting inducible ventricular tachycardia or death

An abnormal signal-averaged electrocardiogram (SAECG) has predictive value for arrhythmic events in patients with idiopathic dilated cardiomyopathy and a normal conduction. The purpose of this study was to investigate whether the presence of a complete bundle branch block (BBB) affects prognostic information of the SAECG. We prospectively obtained SAECGs in 128 patients with idiopathic dilated cardiomyopathy. Forty-three of them had BBB and 85 had a normal QRS duration. According to their clinical history and results of ventricular programmed stimulation, patients were divided into 4 groups: (1) group IA with BBB and ventricular tachycardia (VT) (n = 18); (2) group IB with BBB but without VT (n = 25); (3) group IIA without BBB but with VT (n = 40); (4) group IIB without BBB and without VT (n = 45). Patients were compared with 129 patients without heart disease and without VT. Fifty-seven of them had BBB (group III) and 72 had normal conduction (group IV). The filtered QRS duration was longer in group IB than in group III (175 +/- 21 vs 149 +/- 16 ms, p <0.001), and in group IIB than in group IV (111 +/- 19 vs 96 +/- 12 ms, p <0.05). QRS duration was similar in groups IA and IB (176 +/- 24 vs 175 +/- 21 ms) but longer in group IIA than in group IIB (131 +/- 24 vs 111 +/- 19 ms, p <0.001). The low-amplitude signal duration (LAS) and the root-mean-square voltage (RMS) of the last 40 ms of the filtered QRS did not differ between groups IB and III and IA and IB. LAS and RMS were, respectively, longer (44 +/- 20 vs 31 +/- 13 ms, p <0.01) and lower (21 +/- 20 vs 43 +/- 33 microV, p <0.001) in groups IIA and IIB. In groups IA and IB the combination of 2 of the 3 available criteria: QRS duration >170 ms, RMS <20 microV, LAS >45 ms lead up to the best overall statistical result, with a sensitivity and specificity of 78% and 56%, respectively. In groups IIA and IIB, using conventional late potential criteria, the sensitivity and specificity of the SAECG for VT detection were 65% and 73%, respectively. The risk of sudden death was not predicted by the SAECG, and total cardiac mortality was only dependent on left ventricular ejection fraction. In conclusion, QRS duration was prolonged in all of the patients with a dilated cardiomyopathy compared with those without heart disease. BBB did not change the sensitivity but decreased the specificity of the SAECG to predict any VT risk in dilated cardiomyopathy. The risk of sudden death and total cardiac mortality could not be predicted by the SAECG.

Increased atrial vulnerability in arrhythmogenic right ventricular disease

Supraventricular tachyarrhythmias (SVTA) may occur in patients with the arrhythmogenic right ventricular dysplasia (ARVD). The purpose of the study was to evaluate the incidence of SVTA in 47 patients with ARVD proved by right ventricular angiography. Thirty-three men and 14 women, aged 21 to 72 years (mean 44 +/- 18) were admitted for nonsustained or sustained ventricular tachycardia. Eight patients had a history of spontaneous SVTA several years before ventricular tachycardia occurrence. Protocol of the study consisted of programmed atrial stimulation with one and two extrastimuli delivered during sinus rhythm and two driven rhythms (600 and 400 msec), programmed ventricular stimulation with up to three extrastimuli and was performed in the control state and after infusion of isoproterenol. The results of programmed atrial stimulation were compared with those obtained in 36 asymptomatic subjects without heart disease and with a mean age of 50 +/- 18 years (control group). Sustained SVTA (> 1 minute) was induced in seven of eight patients with spontaneous SVTA, in 27 (69%) of those with ARVD, who did not have spontaneous SVTA, and in two control subjects (5.5%) (p < 0.001). SVTA was inducible in the control state, but ventricular tachycardia induction required isoproterenol in 11 of 27 patients. Two patients without SVTA history but with inducible SVTA developed later spontaneous SVTA. ARVD was associated with a significantly higher incidence of inducible SVTA than in a control population. Supraventricular tachycardias may precede ventricular tachycardias. This association argues for a diffuse myocardial disorder in ARVD.

Paradoxical effect of isoprenaline infusion

BACKGROUND

Isoprenaline (isoproterenol) is a beta-adrenergic drug, used to increase the heart rate and, during electrophysiological study, to facilitate the induction of supraventricular (SVT) and ventricular tachycardias (VT). Decrease in heart rate during isoprenaline infusion is a rare phenomenon. The purpose of the study was to evaluate the incidence, the possible mechanisms, and the significance of a paradoxical bradycardia induced by isoprenaline infusion.

METHODS

Electrophysiological study was performed for the evaluation of tachycardias (n = 551) or dizziness/syncope (n = 214) in 765 patients aged from 15 to 85 years. The study was negative in the basal state, and was repeated after isoprenaline infusion (2-4 microg/min).

RESULTS

In 714 patients, this perfusion increased the heart rate to 100-140 bpm. A bradycardia was noted in 51 patients (7%). Two bradyarrhythmias were noted: (1) sinus or junctional bradycardia (cycle length - 10%) occurred in 43 patients, aged 15-70 years, generally studied for unexplained syncope (n = 37); a young age (40+/-16 years), syncope (n = 37) and absence of heart disease (n = 27) were more frequent than that in patients without isoprenaline-induced sinus or junctional bradycardia; another arrhythmia (SVT or VT) was induced in seven patients with syncope, five with heart disease and two without; six young patients (<50 years) had no syncope and were studied for SVT or VT; (2) eight patients, aged 65+/-11 years, developed second-degree atrioventricular (AV) block which was supraHisian (n = 4) or infraHisian (n = 4); they were studied for exercise-related syncope; they had no signs of myocardial ischaemia and AV block was reproduced by ajmaline testing: isoprenaline revealed organic conduction disturbance.

CONCLUSION

The occurrence of paradoxical bradycardia was a rare finding during isoprenaline infusion (7%); sinus or junctional bradycardia was a sign of hypervagotonia, but was without clinical significance in 35% of these patients. The development of second-degree AV block was always pathological and associated with AV conduction disturbances, which occurred spontaneously during exercise. Isoprenaline infusion appeared to be a simple means to detect organic AV conduction disturbance in patients complaining of exercise or stress-related dizziness/syncope and unable to perform exercise test.

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.

Programmed ventricular stimulation in survivors of acute myocardial infarction: long-term follow-up

The prognostic significance of ventricular tachyarrhythmias induced by programmed ventricular stimulation was evaluated in 492 consecutive survivors of acute myocardial infarction (AMI). Holter monitoring, signal-averaged electrocardiogram (ECG) and measurement of left ventricular ejection fraction (EF) were also performed. The protocol used up to 3 extrastimuli. Sustained monomorphic ventricular tachycardia (VT) < 270 beats/min, > 270 beats/min (ventricular flutter) (VFI), and ventricular fibrillation (VF) were induced in 99, 66 and 52 patients, respectively. Long term follow-up (mean 3.7 +/- 2.2 years) showed that most episodes of VT occurred during the first months following AMI (n = 14), but some patients (n = 6) could develop VT as late as 4 years after AMI. Sudden death (SD) (n = 22) always occurred during the first year following AMI. Multivariate analysis demonstrated that EF < 30% and induction of a VT < 270 beats/min were the only predictors for total cardiac death (P < 0.001). EF < 30%, induction of a VT < 270 beats/min and also of VFI (P < 0.05) were predictors for VT and SD: the risk was 4% in patients without inducible VT, 12% in those with inducible VF1, and 21% in those with inducible VT < 270 beats/min. In conclusion, induction of a sustained monomorphic VT < 270 beats/min or > 270 beats/min is a predictor of arrhythmic events during the first year as well as 4 years after myocardial infarction. However the risk of arrhythmic sudden death decreases after the first year, while the risk of VT persists. Because of the low positive predictive value of programmed stimulation (respectively 21% and 12% for the induction of a sustained VT and VFI), we recommended the indication of programmed stimulation in only the patients with one abnormal non-invasive investigation.

Paroxysmal tachycardia in children and teenagers with normal sinus rhythm and without heart disease

The purpose of this study was to evaluate the value of esophageal programmed stimulation in children and teenagers with normal sinus rhythm ECG and normal noninvasive studies, having palpitations and syncope, and no documented tachycardias. Paroxysmal tachycardias are frequent in children and are often related to accessory connection. These tachycardias are sometimes difficult to prove. Transesophageal atrial pacing was performed at rest and during infusion of isoproterenol in 31 children or adolescents aged 9-19 years (16 +/- 3 years) with normal sinus rhythm ECG and suspected or documented episodes of paroxysmal tachycardia. Sustained tachycardia was induced in 27 patients, at rest in 13 patients, and after isoproterenol in 14 remaining patients. Atrioventricular nodal reentrant tachycardia was found as the main cause of paroxysmal tachycardia (22 cases). Six patients were followed by a vagal reaction and dizziness. These patients had spontaneous tachycardia with syncope. In three other patients, atrial fibrillation was also induced. Concealed accessory pathway reentrant tachycardia was identified in three patients. In two patients, a regular wide tachycardia with right bundle branch block morphology was induced; the diagnosis of verapamil-sensitive ventricular tachycardia was made in a second study by intracardiac study. In conclusion, atrioventricular nodal reentrant tachycardia was found as the main cause of symptoms in children with normal sinus rhythm ECG. Syncope is frequently associated and provoked by a vagal reaction. This diagnosis could be underestimated in adolescents frequently considered as hysterical because noninvasive studies are negative.

Inducible multiform ventricular tachycardia in Wolff-Parkinson-White syndrome

The induction of ventricular tachycardia by ventricular stimulation was investigated in 46 patients with isolated Wolff-Parkinson-White syndrome (10 concealed) and 36 control patients with normal electrocardiograms and conduction systems. None of those studied had spontaneous ventricular arrhythmias or myocardial or valve disease. Single and double ventricular extrastimuli were delivered at 3 cycle lengths (sinus, 600 ms, 400 ms). In the controls ventricular simulation induced one episode (3%) of non-sustained ventricular tachycardia. Ventricular stimulation in patients with Wolff-Parkinson-White syndrome induced two episodes of ventricular fibrillation and 15 episodes of non-sustained multiform ventricular tachycardia (37%). Ventricular arrhythmias were induced only in patients with overt Wolff-Parkinson-White syndrome. In 14 patients the conformation of the electrocardiogram at the start of ventricular tachycardia resembled that of major pre-excitation. The absence of inducible ventricular tachycardia in patients with concealed Wolff-Parkinson-White syndrome suggests that anterograde conduction via an atrioventricular accessory pathway is required to initiate the ventricular arrhythmias: the ventricular tachycardia may be associated with reentry of impulses via atrioventricular connection during the phase of ventricular vulnerability. The similarity between the start of ventricular tachycardia and pre-excitatory complexes may also indicate local reentry into the ventricular area occupied by the bypass tracts. Patients with Wolff-Parkinson-White syndrome and anterograde pre-excitation are more likely to have inducible multiform ventricular tachycardia than individuals without Wolff-Parkinson-White syndrome.