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.

[Frequency of the onset of supraventricular tachyarrhythmias as a function of underlying heart disease]

The prevalence of inducible ventricular arrhythmias is related to the underlying pathology. This study was undertaken to determine the prevalence of supraventricular tachyarrhythmias (SVT), atrial tachycardia, flutter or fibrillation, sustained for over 30 seconds. Programmed atrial stimulation was used to deliver 1 or 2 extrastimuli during sinus and paced rhythm in 230 subjects without obvious cardiac disease (149 without and 81 with spontaneous SVT) and 432 patients with documented cardiac pathology (407 without and 25 with spontaneous SVT). The incidence of inducible SVT with respect to that of spontaneous SVT and in relation to cardiac pathology was as follows: (table; see text) The prevalence of inducible SVT in patients without spontaneous SVT was related to the type of pathology: (table; see text) These results show that in patients with spontaneous SVT the induction of the arrhythmia was facilitated by the presence of underlying cardiac pathology (sensitivity increasing from 67% to 88%). In patients without spontaneous SVT, the nature of the underlying disease was related to the prevalence of inducible SVT, the risk being major in SA block, right ventricular dysplasia and mitral valve prolapse (60-80%) and moderate in dilated CMP and myocardial infarction (35 to 40%).

The tall R wave in lead V1 in posterior myocardial infarction: a reciprocal sign or a His-Purkinje conduction disturbance?

The significance of the tall R wave in lead V1 with an R/S ratio greater than or equal to 1 in posterior myocardial infarction (PMI) was investigated in 28 patients during programmed electrical stimulation. The patients had been admitted with acute PMI documented by electrocardiogram and proven by enzymatic increase. Electrophysiological study was performed 3 weeks after acute PMI. In 17 of the 28 patients (group 1), the tall R wave in V1 disappeared during stimulation: In 13 of them a premature atrial extrastimulus was responsible for an abrupt normalization of QRS complex in V1 related to an increase in AH or HV interval. In the 4 remaining patients the disappearance of the tall R wave in V1 was related to a sinus pause. In 14 patients of group 1, a different prematurity in atrial stimulation induced a right or left bundle branch block (BBB). In 11 of the 28 patients (group 2) the tall R wave in V1 was unchanged but a premature atrial extrastimulus induced a right BBB in 5 patients and a left BBB in 6. In conclusion, the normalization of QRS complex in lead V1 during atrial stimulation or alterations in cycle length suggests that the tall R wave in V1 in PMI is not a simple reciprocal sign of leads V8 V9. Its association with different varieties of BBB and changes in AH or HV intervals could suggest a relationship with a His-Purkinje conduction disturbance in some patients.

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.

[Results of programmed ventricular stimulation in primary dilated cardiomyopathy]

Programmed ventricular stimulation (PVS) has been advocated as being capable of identifying patients with idiopathic non obstructive dilated cardiomyopathy (NOCM) and at high risk of sudden death. We have studied the results of that method in 56 patients aged from 29 to 69 years (mean 53 years) presenting with idiopathic NOCM. The patients were divided into two groups according to the presence or absence of ventricular tachycardia (VT). Group I (controls) comprised 23 patients without documented VT. Group II consisted of 33 patients with documented VT which was sustained in 5 cases. Finally, 7 patients from both groups experienced losses of consciousness. Ventricular stimulation was performed on 2 sites of the right ventricle, using 1 to 3 extrastimuli on 2 imposed cycles. It was repeated under isoprenaline on 25 occasions. PVS induced non sustained ventricular tachycardia (NSVT) in only 2 patients of group I; it reproduced the sustained ventricular tachycardia (SVT) observed in the 5 patients with spontaneous SVT. PVS was negative in 14 of the 28 patients with NSVT; it induced NSVT in 8/28 and SVT in 6/28 (including 4 with more than 280 beats/min). The isoprenaline test failed to induce SVT. 7 patients died suddenly: 3 presented with SVT and 4 had syncopes and NSVT; ventricular stimulation induced SVT in 3 of these 4 patients. It is concluded that induction of sustained VT is uncommon in NOCM, but a history of syncope should prompt a search for SVT. Patients with spontaneous symptomatic NSVT and inducible SVT must be considered at high risk of sudden death.

[Should the Isuprel test be performed systematically in Wolff-Parkinson-White syndrome?]

The isoprenaline (Is) test was designed by Wellens et al. in 1982 to evaluate the effect of catecholamines on the effective refractory period (ERP) of Kent's bundle (K). The purpose of our study was to assess the value of this test in the prognosis of Wolff-Parkinson-White syndrome (WPW), to define its criteria of severity and to determine the usefulness of the test. Out of 33 patients with WPW syndrome, 10 (group I) had a clinical history of severe arrhythmia and 23 (group II) were asymptomatic or had paroxysmal nodal tachycardia. The prognosis of WPW syndrome was evaluated by measuring Kent's bundle ERP under coupled atrial stimulation (S1 S2) and the shortest cycle conducted by K during induced atrial fibrillation (AF) and atrial pacing (AP) both in the basal state (B) and under a 20-30 micrograms Is infusion. (table; see text). Analysis of the results showed constant shortening of ERP in group I and reproduction of the clinical tachycardia in 6 cases. In group II patients isoprenaline unmasked the WPW syndrome in 3 cases and reproduced the clinical tachycardia in 5 cases. The ERP of Kent's bundle evaluated by S1 S2 became smaller or equal to 220 ms in 70 p. 100 of the cases, and this shortening was not specific. The shortest cycle in AF or AP became inferior of equal to 220 ms in only 6 cases, the history being concordant with clinical findings in 4 of them. Altogether, the most reliable and simplest way of evaluating the severity of WPW syndrome is the highest frequency conducted by Kent's bundle in atrial pacing during the Is test which should be performed in all patients in view of its specificity, simplicity and safety.

[Factors predicting the response to an antiarrhythmic during an electrophysiologic study for ventricular tachycardia]

The purpose of this study was to search for factors correlated with the absence of reinduction of a clinical ventricular tachycardia (VT) by stimulation in patients under anti-arrhythmic treatment. Repeated stimulations were performed in 41 patients with spontaneous VT and sustained, monomorphous ventricular arrhythmia induced by stimulation. The stimulation included 1 or 2 extrastimuli delivered into the right ventricle in sinus rhythm, then in imposed ventricular rhythm (600-400 ms). At least 4 anti-arrhythmic drugs were tested. In 16 patients (group I) of mean age 51 +/- 11 years VT was no longer reinducible under anti-arrhythmic treatment. In 25 patients (group II) of mean age 57 +/- 12 years no anti-arrhythmic drug was able to prevent VT induction. The characteristics of spontaneous and induced VT and of isotopic left ventricular ejection fraction (LVEF) were compared in both groups. The absence of reinduction of VT was obtained more easily in patients with: spontaneous, frequently unsustained VT; VT requiring 2 ventricular extrastimuli delivered in imposed rhythm to be induced; rapid initial induced VT (cycle 233 +/- ms vs 297 +/- 63 ms); less advanced underlying heart disease (LVEF 38 +/- 18 vs 27 +/- 13%). The subsequent history of the patients showed that the absence of reinduction of VT was correlated with a low risk of recurrence of VT (12.5 vs 48%) and with a lower risk of mortality (6% vs 32%) than in patients whose VT was always inducible under anti-arrhythmic treatment.

[Prognostic value of ventricular tachycardia induced by stimulation in patients without documented tachycardia]

In order to determine the cause of syncopes or disorders of conduction, 584 programmed stimulations using 2 ventricular extrastimuli delivered during an imposed rhythm were performed, between 1981 and 1985, in patients without ventricular tachycardia (VT) proven by Holter recordings. Eighty-seven non-sustained VT (NSVT) (15%), 8 ventricular fibrillations (VF) (1%), 16 ventricular flutters (VF1) (3%) and 23 sustained VT (SVT) (4%) were induced. To appraise the significance of these responses the patients were followed up for a mean period of 2 +/- 1 years. Among the NSVT patients the first 47 were followed up until 1984 and the others, less numerous, until 1985. Patients who responded to stimulation with NSVT had (4.4%) or did not have an underlying cardiopathy; their mean left ventricular ejection fraction (LVEF) was 53.5 +/- 17% (n = 10); 17% died of heart disease, but the disease was related to VT in only one case; 36% of these patients had cardiac symptoms, but only one presented with episodes of NSVT. Patients who responded with VF had a normal (50%) or abnormal heart; their mean LVEF was 52 +/- 19%; one died of heart failure, the others were asymptomatic. All but one of the patients who responded with VF1 had an underlying cardiopathy and a mean LVEF of 38 +/- 19%; 3 died, 2 of heart failure and 1 of sudden death; 13 were asymptomatic. All patients who responded with SVT had an underlying cardiopathy and a mean LVEF of 37 +/- 13%; 7 (30%) died, including 2 sudden deaths; 2 had episodes of VT and 12 were asymptomatic. In summary, an underlying cardiopathy was present in one-half of the patients who responded with NSVT or VF and in all patients who responded with VF1 or SVT. The risk of VT was low (5%) in patients who responded with NSVT, VF or VF1 and was higher (17%) in those who responded with SVT.

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.

Effect of flecainide on left ventricular ejection fraction

Antiarrhythmic agents may depress cardiac contractility and worsen heart failure. Flecainide is an effective antiarrhythmic drug, but when administered orally in patients with left ventricular (LV) dysfunction, its effect on LV function is unknown. To assess the effects of flecainide on cardiac function, LV ejection fraction (LVEF) was measured by radionuclide ventriculography in 36 patients with LV dysfunction (LVEF less than or equal to 40%), prior to, and 7 days after, drug therapy was initiated. To analyse the possibility of a dose-dependent effect on LVEF, 18 patients received 200 mg day-1 of flecainide and 18 patients with an identical initial LVEF (27 +/- 8 vs 27 +/- 9) (NS) received 300 mg day-1. The study was stopped in 7 patients because of severe cardiac adverse effects; in these patients the LVEF was significantly lower (15 +/- 7) than that of the 29 patients who completed the protocol (27 +/- 8) (P less than 0.01). In patients who completed the protocol, there was no significant change in LVEF either with a daily dosage of flecainide of 200 mg day-1 (27 +/- 8 vs 27 +/- 8) or with 300 mg day-1 (27 +/- 9 vs 28 +/- 13). Thus, in the patients with LV dysfunction studied, oral flecainide did not significantly affect LV function either with a low or with the usual daily dosage. However, in patients with severe impairment of LV function (LVEF less than 30%) flecainide must be used carefully owing to a higher incidence of adverse effects on cardiac rhythm.

[Outcome of 195 patients with Wolff-Parkinson-White syndrome]

Between 1974 and 1984, 207 patients with Wolff-Parkinson-White syndrome (WPW) were admitted to our hospital department; 195 of them were followed up for periods ranging from 1 to 12 years (6 years in children, 3 years and 9 months in adults on average); 160 had undergone electrophysiological exploration. Fifty-seven patients were less than 16 years old: 7 died, including 6 with associated congenital heart disease; an asymptomatic 12-year old girl died suddenly while taking part in a sporting event. The signs of WPW disappeared in 5 out of 10 children under 1 year of age. One hundred and thirty-eight patients were older than 15: 15 of them died, but only 3 deaths were related to WPW: one was consecutive to surgery for WPW and one to fulguration; the third patient died of WPW tachyarrhythmia; the refractory period of his Kent's bundle was short, but his compliance with treatment was irregular. We found no correlation between changes in functional symptoms and Kent's bundle refractory period values; paradoxically, the frequency of attacks and resistance to treatment was higher in cases with long refractory period. On the whole, this series confirms that WPW usually is a benign disease. However, the risk of sudden death, of which it offers an example, indicates that all patients with WPW should be evaluated with at least an exercise test and, depending on its results or on the socio-professional context, an electrophysiological exploration.

[Correlation between late surface potentials and inducible ventricular arrhythmias. Apropos of 115 cases]

Programmed ventricular stimulation and a search for late surface potentials (LP) by means of signal-averaging and quantification by Simson's method were performed in 115 patients divided into five groups: group I (n = 50) with no myocardial infarction (MI) and no clinical or induced ventricular tachycardia (VT); group II (n = 28) with MI and no clinical or induced VT; group III (n = 8) with MI, no clinical VT but induced non sustained VT (NSVT); group IV (n = 19) with MI, no clinical VT but induced sustained VT (SVT); group V (n = 15) with clinical and induced VT. The terminal portion of the averaged signal (AS) was analyzed by three parameters: duration of AS terminal portion less than 40 microvolts (Dur TP), AS amplitude 50 and 40 ms before its end (Amp 50, Amp 40). The presence of TP was defined in two ways: criterion A = Amp 40 less than 25 mcv, criterion B = at least two sub-criteria: Dur TP greater than 40 ms, Amp 50 less than 25 mcv, Amp 40 less than 15 mcv. Compared to groups I and II, the AS of group V was characterized by a prolonged and low amplitude terminal portion (p less than 0.001). Groups III and IV were intermediate. The incidence of TP in groups I to V was 20, 28, 37, 56 and 80% respectively with criterion A, and 4, 4, 0, 28 and 66% respectively with criterion B. The lower incidence of TP in group IV as compared to group V was probably due to the induction of purely artefactual SVT's, notably those with rapid cycle (greater than 270 cps/min) which are remarkable on several accounts.(ABSTRACT TRUNCATED AT 250 WORDS)

[Sudden death during Holter recording. Possible iatrogenic role of cardiovascular drugs. 10 cases]

Ten patients who presented with advanced heart disease and severe ventricular arrhythmia could be considered "at high risk of sudden death" caused by ventricular fibrillation. Yet they died suddenly while under Holter monitoring, and the recordings demonstrated that 4 of these deaths were due to a major disorder of conduction and 6 to ventricular fibrillation. Further analysis of these cases showed that the lethal disturbance of heart rhythm was ascribable to an anti-arrhythmic drug in 5 cases (2 with conduction disorder, 3 with ventricular fibrillation). It would appear that although patients of this kind need anti-arrhythmic drugs, these should be given with caution and in lower doses than in patients with normal left ventricular function.

[Short PR-normal QRS syndrome, pre-excitation syndrome or a variant of normal conduction?]

An electrophysiological exploration was carried out in 48 patients presenting a syndrome short PR-small QRS (group I), compared to a reference group of 537 patients who did not present this abnormality and had no previous history of Bouveret's tachycardia (group II). The most remarkable abnormality in group I is an acceleration of the anterograde nodal conduction with a Wenckebach point beyond 200/min, significantly more frequent than in group II. The retrograde conduction is also excellent in group I, but without significant difference in comparison to patients from group II who have an accelerated anterograde conduction. The risk of triggering a supraventricular tachycardia is not statistically more important in group I than in group II. However, an accelerated nodal conduction presents an increased risk of triggering a supraventricular tachycardia, in group I as well as in group II. It is therefore concluded that the syndrome short PR-small QRS is, in the large majority of cases, only an aspect of the syndrome of accelerated nodal conduction, a variant of normal conduction. It is only in a few rare observations that it can be ascribed to the probable presence of pre-excitation fibers: 2 cases out of 48 in this series.

[Diagnostic value of the isoproterenol test in effort tachycardia]

An isoproterenol test was performed in 69 patients during electrophysiological investigation to assess its diagnostic value in adrenergic supraventricular or ventricular tachycardia. Sixteen control subjects had no symptoms on exercise and routine exercise stress testing did not trigger any hyperexcitability. Sixteen patients had reproducible documented supraventricular tachycardia induced by exercise (13 paroxysmal junctional tachycardias, 3 focal atrial tachycardias). Eight patients had ventricular hyperexcitability related to effort. Twenty-nine patients had supraventricular and/or ventricular hyperexcitability only at rest. Electrophysiological investigations included paired atrial stimulation during sinus rhythm and paced rhythm followed by programmed ventricular stimulation using one and then two extrastimuli delivered during sinus rhythm and paced ventricular rhythm. These stimulation studies were carried out under basal conditions and then during low dose isoproterenol infusion (10 to 40 micrograms) which accelerated the heart rate to 130/mn. Electrophysiological and conduction parameters and the mode of induction of the tachycardia (defined as at least 5 successive echos with a configuration similar to the clinical tachycardia) were studied. We observed an acceleration of anterograde and retrograde conduction and a shortening of the effective atrial and ventricular refractory periods but these changes were found equally in the different groups of patients and were not related to the induction of tachycardias. The induction of paroxysmal junctional tachycardia by isoproterenol was a very sensitive (92%) and specific (100%) diagnostic method. Its diagnostic value was much greater than Holter monitoring (25%) and exercise stress testing (12.5%). Induction of ventricular tachycardia by isoproterenol was also very sensitive (75%) and specific (95%). The diagnostic value was higher than exercise stress testing (71%) and Holter monitoring (62%). Isoproterenol did not affect the induction of spontaneous tachyarrythmias unrelated to effort and even suppressed the triggering of some episodes. In conclusion, the induction by atrial or ventricular pacing or spontaneous supraventricular or ventricular tachycardia during isoproterenol infusion was very specific and correlated with the concept of tachycardia induced by exercise and therefore of adrenergic nature. The sensitivity of this test was excellent in patients with supraventricular tachycardia (95%) and very good in ventricular tachycardia (75%). On the other hand, the changes in the electrophysiological parameters were not specific for a group of patients.

Loss of efficacy of flecainide in the Wolff-Parkinson-White syndrome after isoproterenol administration

Although anterograde conduction through a Kent bundle with a short refractory period was suppressed by 300 mg of flecainide acetate, the infusion of small amounts of isoproterenol caused the reappearance of WPW and permitted the induction of an atrial tachycardia with 1/1 conduction through the accessory pathway at a rate of 260 beats min-1. This case shows that the effect of isoproterenol may be maintained after apparently successful flecainide therapy.

[Cardiac electrophysiologic effects of prostacyclin in man]

The electrophysiological effects of prostacyclin (PGI2) at increasing doses (2.5, 5 and 10 ng/kg/min) were assessed in 16 patients during classical investigations of sinus node function and atrioventricular conduction and during programmed atrial and right ventricular under basal conditions and during prostacyclin perfusion. Ten patients had normal sinus node function and atrioventricular conduction under basal conditions. Stastistically significant changes were observed during PGI2 perfusion: shortening of the sinus cycle length (p 0.01), decreased intraatrial conduction time (p less than 0.05), reduced atrial functional refractory period (p less than 0.01) and reduced effective and functional refractory periods of the AV node (p less than 0.05), increased anterograde (p less than 0.01) and retrograde (p less than 0.05) Wenckebach point. The changes were dose dependent. No significant changes were observed in sinus node recovery periods of the His Purkinje system. Similar changes were recorded on 4 other patients with various conduction defects. Paired atrial stimulation induced manifestations of hyperexcitability in 5 patients. In 2 patients with normal responses under basal conditions it was possible to induce non-sustained atrial tachycardia during PGI2 administration. In 3 patients with inducible atrial tachycardia under basal conditions, it was still possible to induce the tachycardia after PGI2 but this disappeared in all but one patient with the sick sinus syndrome after the addition of propranolol. The changes in ventricular excitability were studied by a specific protocol in 16 patients. Of the 13 patients without inducible ventricular tachycardia under basal conditions, 4 developed inducible non-sustained ventricular tachycardia after PGI2. Three patients had inducible VT under basal conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

Proarrhythmic and antiarrhythmic effects of intravenous prostacyclin in man

Prostacyclin (PGI2) has been shown to reduce the occurrence of experimental ventricular arrhythmias. To assess potential beneficial effects in man, the electrophysiological action of PGI2 was studied in 16 non medicated patients. The protocol used in incremental pacing and programmed stimulation in the right atrium and ventricle. This protocol and measurement of effective refractory periods (ERP) were performed before and during the injection of 2.5, 5 and 10 ng kg-1 min-1 of PGI2. The atrial functional refractory period decreased significantly (P less than 0.05); PGI2 had no influence on the occurrence of inducible non-sustained (NS) atrial tachycardias and was responsible for the occurrence of 2 non-sustained atrial tachycardias in 8 patients with inducible atrial echo beats under basal conditions. Thirteen patients did not have inducible ventricular tachycardia (VT) under basal conditions. Non-sustained VT was induced after PGI2 in 4 of them but in only 1 of them after the administration of propranolol. Three patients had inducible VT under basal conditions (1 non-sustained, 2 sustained VT). PGI2 did not prevent the occurrence of VT (1 non-sustained, 1 sustained VT), except in 1 patient with ischaemic-related VT, who had non-sustained VT after PGI2. In conclusion, PGI2 does not seem to have a cardiac antiarrhythmic effect and may increase the atrial and ventricular repetitive response. This effect could be related to an increase of adrenergic tone.