[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.

Failure of the exercise test to predict the anterograde refractory period of the accessory pathway in Wolff Parkinson White syndrome

Modifications of the delta wave on the surface ECG during an exercise stress test were compared to electrophysiological variations in accessory pathway (AP) refractoriness and in AV node conduction, during intravenous isoproterenol infusion in ten patients with WPW syndrome. In one patient, the delta wave persisted unchanged at the end of exercise and, with isoproterenol, there was a greater reduction in the AP anterograde effective refractory period (AERP) than in AV node conduction time. In three patients, the delta wave became less and less apparent but without completely disappearing; in these patients, the slight reduction of the AERP in the accessory pathway with isoproterenol was comparable to the reduction in AV node conduction time, explaining the progressive fusion between the two activation fronts. In the six other patients, the delta wave completely disappeared during exercise: in two cases, suddenly from one cycle to the next with strong concordance between the measured (isoproterenol) and the estimated (exercise test) AERP in the AP; in four cases, the disappearance was progressive with a significantly greater reduction in the AV node conduction time than in the measured AERP of AP which was nonetheless very short, 190 to 225 ms, during isoproterenol infusion. These findings confirm the limitations of the exercise test to predict the AERP of the AP. In addition, they demonstrate that modifications in the delta wave during exercise result from a balance between the relative effects of sympathetic stimulation on refractoriness of AP and normal AV conduction.

Procainamide infusion test: inability to identify patients with Wolff-Parkinson-White syndrome who are potentially at risk of sudden death

Persistence of preexcitation in sinus rhythm with procainamide infusion has been reported to occur in patients with a short anterograde accessory pathway effective refractory period (AERPAP) and this test has been proposed as a reliable noninvasive method to identify patients with the Wolff-Parkinson-White syndrome who are at risk of sudden death. However, sudden death correlates best with a shortest preexcited RR interval during atrial fibrillation (SRRPE) of 260 msec or less. We infused 10 to 12 mg/kg procainamide to 56 patients to determine whether persistence or loss of preexcitation in sinus rhythm identified patients with SRRPEs of 260 or less or greater than 260 msec, respectively. Atrial fibrillation was induced in 53 patients. Of these, 32 patients had persistence of preexcitation with procainamide infusion and SRRPE in this group of patients was shorter than that in patients in whom preexcitation was lost (194 +/- 44 vs 235 +/- 55 msec, p less than .05). However, preexcitation persisted after procainamide infusion in only 31 of 46 (67%) patients with SRRPEs of 260 msec or less. Furthermore, 15 of 21 patients who lost preexcitation had SRRPEs of 260 msec or less and two of these patients had a history of ventricular fibrillation. The correlation between AERPAP and SRRPE was studied in a separate group of 79 patients with single accessory pathways. There was a significant (p less than .001) but poor (r = .58) correlation between these two variables. Thus, the procainamide test regarding accessory pathway refractoriness often cannot be extrapolated to SRRPE.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparative effects of adenosine triphosphate on accessory pathway and atrioventricular nodal conduction

Adenosine triphosphate (ATP) has potent negative dromotropic effects on the atrioventricular (AV) node, but variable effects on accessory pathway conduction have been described. The effects of an intravenous bolus injection of 8 mg ATP on accessory pathway and AV nodal conduction were determined during electrophysiologic testing with controlled atrial and ventricular rates. AV conduction was monitored during atrial or ventricular pacing at a constant cycle length, 30 msec longer than the cycle length at which block occurred. During atrial pacing antegrade block after administration of ATP occurred in 1 of 30 (3.2%) patients with accessory pathway conduction and 12 of 13 (92%) patients with AV nodal conduction (p less than 0.001). During ventricular pacing only 5 of 26 (16%) patients had accessory pathways blocked, whereas 25 of 35 (71%) patients with AV nodal conduction had block (p less than 0.001). Thus, failure of ATP to produce ventriculoatrial block identified the presence of an accessory pathway with a sensitivity of 84%, specificity of 71%, and predictive value of 72%. There was no correlation between accessory pathway properties and the effects of ATP. The effects of ATP on the AV node were concordant with the effects of a combination of verapamil and propranolol in 21 of 23 patients, suggesting that this dose ATP is an equipotent AV nodal blocker with a short duration of action. Thus, although the effects of ATP on accessory pathways and the AV node differ, block in ventriculoatrial conduction after administration of ATP cannot be used as the sole criterion to distinguish the mechanism of conduction.

A simple bedside technique in the study of the WPW syndrome

A simple method for the study of the WPW syndrome, which can be performed at the patient's bedside, is presented. Using standard ECG, vagal maneouvers, ajmaline test, precordial mapping, vectorcardiography, electrode catheters positioned in the right atrium and esophageal catheters, the site of accessory pathways, and the complex arrhythmias occurring in these patients can be understood and medically treated.

Supraventricular tachyarrhythmias. Mechanisms, types, and management

Advances in the area of clinical electrophysiology have allowed definition of the mechanisms of most forms of supraventricular tachyarrhythmias. Reentry, automaticity, and triggered activity are the three basic mechanisms. Treatment of the arrhythmias is based on frequency and hemodynamic severity. After accurate diagnosis, empirical therapy with currently available medications usually controls symptomatic supraventricular tachyarrhythmias. Nonpharmacologic therapy with permanent antitachycardia pacemakers, percutaneous catheter ablation, or surgery is indicated for selected patients with medically recalcitrant supraventricular tachyarrhythmia.

Electrophysiologic studies in cardiac arrhythmia. When and why they are useful

Electrophysiologic studies have contributed significantly to the improved understanding of cardiac arrhythmias. Whereas previously treatment of these arrhythmias was largely empirical, electrophysiologic studies have paved the way for a scientific approach to evaluation and management of the patient with a potentially life-threatening problem.

The supraventricular tachycardias

Most supraventricular tachycardias can be diagnosed confidently using the standard 12-lead electrocardiogram, the more so if such a tracing in sinus rhythm is also available. The underlying mechanisms may often be determined and these may have important therapeutic consequences. This chapter reviews the electrocardiographic appearances of the supraventricular arrhythmias. Extrasystoles are common but rarely require specific treatment. Automatic atrial tachycardias are common and usually amenable to simple management. Reentrant circuits related to atrial and atrioventricular tachycardias are also described, and where possible, treatment is related to underlying mechanisms.

Latent pre-excitation: exposure of anterograde accessory pathway conduction during atrial fibrillation

In three patients anterograde conduction across a previously undocumented accessory pathway was exposed by the development of atrial fibrillation. This unusual presentation illustrates the possible unmasking of the Wolff-Parkinson-White syndrome by other factors in patients who have not previously demonstrated the potential for anterograde accessory pathway conduction.

Intermittent Wolff-Parkinson-White syndrome due to phase 3 and phase 4 block: disappearance of rapid ventricular response during atrial fibrillation

A 65-year-old man with Wolff-Parkinson-White syndrome type A had a rapid ventricular response over an accessory pathway during atrial fibrillation. Four months later, electrophysiological study revealed the following properties: 1) The antegrade accessory pathway conduction showed phase 3 and phase 4 block. 2) The retrograde concealed accessory pathway conduction eliminated phase 4 block in the antegrade accessory pathway conduction. 3) Premature ventricular excitation arose from the accessory pathway or from the ventricular muscle close to its distal end. 4) Atrial fibrillation during isoproterenol infusion did not show rapid ventricular response. Spontaneous impairment of accessory pathway conduction due to phase 3 and phase 4 block was suspected.

Oncocytic cardiomyopathy of infancy with Wolff-Parkinson-White syndrome and ectopic foci causing tachydysrhythmias in children

Two female infants, ages 6 months and 13 months, were first seen in the newborn period with supraventricular tachycardia associated with Wolff-Parkinson-White syndrome. One infant had echocardiographic and angiographic evidence of diffuse cardiomyopathy and died suddenly at home. The other infant was seen initially at 13 months of age with refractory ventricular tachycardia and died following surgical resection of arrhythmogenic foci on the left and right ventricles. Autopsy showed diffuse patchy oncocytic cardiomyopathy in both instances. Serial histologic sections of the cardiac conduction system showed oncocytic involvement of the atrioventricular (AV) node, His bundle, and bundle branches. Both infants had interruption of the anulus fibrosus by oncocytic cells at several sites, resulting in multiple accessory AV and nodoventricular connections. Additionally, patient No. 1 had an accessory AV connection by oncocytic cells in the fatty fibrous tissue of the left AV sulcus. To our knowledge, this is the first report of multiple accessory AV connections of oncocytic cells seen during histologic study. In addition, both infants had oncocytic involvement of the exocrine and endocrine glands. This report discusses the clinicopathologic correlations in these two patients, the literature on oncocytic cardiomyopathy, and the types of dysrhythmias found in these patients and their management.

[Supraventricular tachycardia of the fetus in the 3d trimester of pregnancy following persistent supraventricular extrasystole]

Persistent supraventricular extrasystoles are antepartally, intrapartally and postpartally the most frequent form of arrhythmias, and do not cause fetal congestive heart failure (hydrops fetalis). The premature beats often disappear spontaneously prenatally, but in most cases within the first two weeks of life. The extremely rare observation of the occurrence of a supraventricular tachycardia in the 37th week of gestation in a fetus with persistent supraventricular extrasystoles from the 20th week of gestation onward and with a postnatally diagnosed Wolff-Parkinson-White syndrome is described. Because of the importance of this complication of supraventricular extrasystoles (a supraventricular tachycardia of the fetus can cause a cardiac failure with hydrops fetalis and eventually intrauterine death), it is important that all fetuses with supraventricular extrasystoles be closely monitored by frequent observation of the fetal heart rate using ultrasound (M-mode-echocardiography), cardiotocography and auscultation. Postpartally a cardiologic examination of these newborn infants is necessary, particularly in order to exclude the presence of a preexcitation.