Clues to the electrocardiographic diagnosis of subtle Wolff-Parkinson-White syndrome in children

The electrocardiographic diagnosis of Wolff-Parkinson-White syndrome (WPW) may be missed because delta waves can be subtle in children, so we examined 66 electrocardiograms from patients with proven WPW, 24 from those with questionable WPW ("subtle WPW"), and 369 consecutive electrocardiograms from control patients to identify additional clues that WPW might be present. Three features were notable in WPW: no Q wave in left chest leads (88%), PR interval less than 100 milliseconds (80%), and left axis deviation (33%). In subtle WPW these findings were similar: 79%, 67%, and 46%, respectively. By comparison, 5% of control subjects had no Q wave, 16% had a PR interval of less than 100 milliseconds, and 4% had left axis deviation (all p less than 0.001). The coexistence of two of these features was common (74%) in WPW and subtle WPW (63%) but rare (2%) in control subjects (p less than 0.001). A PR interval of less than 100 milliseconds was less specific before 1 year of age, but 89% of patients with WPW had a QRS duration of greater than 80 milliseconds versus 2% of control subjects (p less than 0.001). Obvious WPW disappeared later in 11 patients; however, left axis deviation or lack of a Q wave persisted in eight (p less than 0.01). We conclude that the diagnosis of WPW in children, even when subtle, is suggested by the presence of these four changes. Preexcitation may persist in some patients in whom overt delta waves are no longer present.

[Arrhythmia in patients with mitral valve prolapse]

An incidence of cardiac arrhythmias was evaluated in 119 patients with mitral valve prolapse. The disease was made basing on the results of clinical symptoms, echo-, angio- and phonocardiography. Electrocardiograms were recorded from the standard 12 lead and Holter technique for 24 hours in each patient to assess present arrhythmias. It was found that the most frequent cardiac arrhythmias accompanying mitral valve prolapse are ventricular extrasystolic contractions of Lown's class 1a and 1b. Only examination of strictly selected groups of patients (age groups with or without co-existing mitral valve insufficiency for adequate period of time) will facilitate precise evaluation of an incidence of different cardiac arrhythmias accompanying the underlying disease.

Supraventricular tachycardia due to Wolff-Parkinson-White syndrome in children: early disappearance and late recurrence

The clinical course of 140 patients with Wolff-Parkinson-White syndrome who had their initial episode of supraventricular tachycardia before 18 years of age was reviewed. Among those whose tachycardia began at age 0 to 2 months, it disappeared in 93% and persisted in 7%. In 31%, it disappeared and reappeared at an average age of 8 years. Among patients whose tachycardia was present after age 5 years, it was persistent in 78% at a mean follow-up period of 7 years. Accessory connection location was mapped by electrophysiologic study in 87 patients and estimated by electrocardiography in 53 patients. There were no differences in tachycardia onset or recurrence based on accessory connection location. Congenital heart defects were present in 37% of all patients, 23% of whom had Ebstein's anomaly. Among all patients who underwent cardiac catheterization, 63% of those with a congenital heart defect had a rightsided accessory connection, whereas 61% of patients with a normal heart had a left-sided connection (p less than 0.01). Multiple accessory connections were found in 12% of patients with a congenital heart defect compared with 6% of those without such a defect.

IN CONCLUSION

1) supraventricular tachycardia due to Wolff-Parkinson-White syndrome that begins in infancy may disappear, but it frequently recurs in later childhood; 2) if tachycardia is present after age 5 years, it persists in greater than 75% of patients; and 3) the location of the accessory connection does not affect the clinical course of tachycardia in children with Wolff-Parkinson-White syndrome.

Prognostic value of electrophysiology testing in asymptomatic patients with Wolff-Parkinson-White pattern

The prognostic value of electrophysiology testing was studied in 75 asymptomatic patients with the Wolff-Parkinson-White electrocardiographic pattern. All patients underwent electrophysiology testing at entry to the study and were followed up annually for a total of 348 patient-years (median, 4.3 years). There were 44 male and 31 female patients, and age at enrollment ranged from 7 to 77 years (mean, 34 +/- 14 years). The median effective refractory period of the accessory pathway was 293 msec (interquartile range, 280-310 msec), and the median shortest RR interval between preexcited beats during atrial fibrillation (SRR) [corrected] was 274 msec (240-320 msec). Twenty-three patients had an SRR of 250 msec or less and eight patients had a median shortest SRR interval of 200 msec or less. Twelve patients had inducible sustained reciprocating tachycardia, 10 patients had inducible nonsustained reciprocating tachycardia, and 23 patients had inducible sustained atrial fibrillation. Twenty patients (27%) lacked retrograde conduction over the accessory pathway. No patient died suddenly during a median follow-up of 4.3 years. Six patients (8%) became symptomatic with documented supraventricular tachycardia, of whom two underwent operative ablation of their accessory pathways. No patient with absent retrograde accessory pathway conduction during the electrophysiology study became symptomatic. Inducible sustained or nonsustained reciprocating tachycardia at electrophysiology study did not predict the development of subsequent symptomatic supraventricular tachycardia. Nine patients lost preexcitation during follow-up. Age at enrollment (relative risk/decade, 1.4; 95% confidence interval, 1.0-1.8) and anterograde accessory pathway refractory period (relative risk, 1.06/10 msec; 95% confidence interval, 1.0-1.12) were independent predictors of loss of preexcitation.(ABSTRACT TRUNCATED AT 250 WORDS)

Mechanism of intermittent preexcitation in the Wolff-Parkinson-White syndrome. The concept of electronically mediated conduction across an inexcitable gap

A man with intermittent preexcitation in the Wolff-Parkinson-White syndrome is reported. Once a sinus impulse was blocked in the accessory pathway, the block (ie, loss of preexcitation) was continued for a while until a PP interval reached or exceeded a critical period inducing sudden reappearance of preexcitation. This critical period was considerably longer than the effective refractory period of the accessory pathway. These findings are explained by the use of the concept of electronically mediated conduction across an inexcitable gap in the accessory pathway. It seems that when loss of protection was maintained, the sinus impulse was blocked at the site proximal to the gap, but the impulse passing through the atrioventricular node always reached retrogradely the site distal to the gap, and therefore, the next sinus impulse was blocked again.

Transesophageal electropharmacologic test in a newborn with familial Wolff-Parkinson-White syndrome

A newborn infant with familial Wolff-Parkinson-White (WPW) syndrome presented with a supraventricular tachycardia of 300 beats/min, refractory to digoxin and flecainide administration. Serial electropharmacologic tests were performed via the esophagus before and during oral therapy with verapamil at 40, 80, and 60 mg daily. Before treatment, tachycardia could be induced with programmed stimulation. A regimen of verapamil at 60 mg daily, which resulted in the initiation of nonsustained (less than 10 s) reciprocating tachycardia only, without clinical recurrences, was identified as suitable long-term oral therapy. The efficacy of this drug regimen in preventing episodes of tachycardia was confirmed during a 1-month follow-up period. It is concluded that transesophageal atrial pacing is a useful, noninvasive means of selecting treatment in neonates with supraventricular tachycardia, when nonconventional drugs are considered for prophylaxis.

Multichannel biomagnetic system for study of electrical activity in the brain and heart

The authors designed a multichannel system for noninvasive measurement of the extremely weak magnetic fields generated by the brain and the heart. It uses a flat array of 37 superconducting magnetic field-sensing coils connected to sophisticated superconducting quantum interference devices. To prevent interference from external electromagnetic fields, the system is operated inside a shielded room. Complete sets of coherent data, even from spontaneous events, can be recorded. System performance was evaluated with phantom measurements and evoked-response studies. A spatial resolution of a few millimeters and a temporal resolution of a millisecond were obtained. First results in patients with partial epilepsy and investigations of the cardiac conductive pathway indicate that biomagnetism is now ready for a systematic clinical evaluation. Interpretation of measurements was facilitated by highlighting biomagnetically localized electrical activity in three-dimensional digital magnetic resonance images.

Body surface mapping and nontraditional ECG leads in patients with Wolff-Parkinson-White syndrome

A method of ECG mapping from 90 points on the chest surface is described in 41 male and 17 female patients, aged 6 to 59 years. All also underwent invasive electrophysiological investigation and intraoperative epicardial mapping. Fifty-two patients had one, three patients two, and one patient had three anomalous accessory pathways. Two patients had nodoventricular tracts (Mahaim fibers). We distinguished seven zones along the atrioventricular groove (AVG) to compare the data derived from epicardial, endocardial, and body surface mapping. A microcomputer was used for the analysis of all ECGs to construct and analyze the isopotential maps. The criterion for localization of the anomalous accessory pathways was determined after analysis of the data from all 58 patients. The localization criterion was the appearance of a minimal deflection (-0.09 +/- 0.03 mV) on the surface isopotential maps within the first 0.28 msec of the QRS complex. This criterion for localization of anomalous accessory pathways from the chest surface was proposed on the basis of comparison of data from selective coronary angiography, the ventriculogram, and the chest X ray i.e., radiographic-topographic-anatomical data. In 20 patients, 10-20 nontraditional ECG leads were recorded from the chest to reflect the atrioventricular groove. The number of nontraditional ECG leads depended on patient age, weight, and height. Localization of the accessory pathway in one of the seven zones was established by the earliest delta wave and its maximum deviation. It was possible to localize the anomalous accessory pathway and to suspect multiple pathways in 95% of cases using nontraditional ECG leads and the listed criteria.(ABSTRACT TRUNCATED AT 250 WORDS)

Noninvasive evaluation of supraventricular tachycardias

In this article we discuss the role of noninvasive methods in evaluation of supraventricular tachycardias. The limitation of Holter monitoring and exercise testing is discussed. A significant portion of the article is devoted to the role of esophageal recording, body surface potential mapping, and phase image analysis, areas that are often underutilized but that have potential in the diagnosis of supraventricular tachycardias.

Alternating Wolff-Parkinson-White syndrome associated with attack of angina

In a patient with Wolff-Parkinson-White syndrome and an inferior-posterior bypass tract, transient restoration of normal conduction occurred during an attack of angina. The ECG pattern of inferior posterior ischemia was present when the conduction was normal. Thallium scintigraphy showed a reversible posterolateral perfusion defect. The possible mechanisms for production of intermittent preexcitation are discussed.

Acceleration of conduction within an accessory pathway with propafenone

We describe a case of dangerous acceleration of conduction through an accessory pathway produced by the Class IC agent propafenone during routine electrophysiological study of a patient with Wolff-Parkinson-White syndrome. This pro-arrhythmic effect has not previously been described with this drug. Propafenone is now being more widely used since the publication of the preliminary results of the CAST Study in the U.S.A.

[Wolff-Parkinson-White syndrome: long-term follow up study in a pediatric population (86 cases)]

Eighty six patients (48 males and 38 females) with W-P-W diagnosed before the age of 15 years had a maximum follow-up of 20 years. The mean age at diagnosis was 3 y and 5 m., most cases being concentrated in the first 6 months of life (37%). Twenty seven (31.4%) had associated heart disease, the more common being: ventricular septal defect (6 cases), Ebstein malformation (5 cases) and transposition of the great arteries (4 cases). Supraventricular tachycardia (SVT) was the commonest form of clinical presentation, followed by examination because heart murmur or heart disease. Fifty patients (58%) had SVT along the follow-up. SVT was more frequent in W-P-W type A than in type B (p less than 0.05). There was a statistically significant correlation (p less than 0.001) between the association of SVT and the absence of heart disease, but the finding must be questioned because the true incidence of W-P-W in normal population is unknown. There also were a significant correlation (p less than 0.05) between the association of W-P-W type B and the presence of heart disease. An electrophysiologic study was performed in 11 patients, 6 of them being concealed W-P-W. Four patients were operated upon because of SVT. We have studied a total of 154 SVT episodes in the 50 patients with SVT. The treatment more frequently used to finish the SVT included: verapamil, DC-Countershock and Digoxin.(ABSTRACT TRUNCATED AT 250 WORDS)

Current management of the Wolff-Parkinson-White syndrome

The Wolff-Parkinson-White syndrome is a multifaceted disorder that ranges from asymptomatic to life threatening. Accounting for approximately 20% of cases of paroxysmal supraventricular tachycardia and with a prevalence perhaps as high as 1 per 500, it is far from a rare disorder. Considering the potentially lethal complications following the administration of digoxin or verapamil, all physicians treating arrhythmias should know when to suspect the Wolff-Parkinson-White syndrome. A careful review of electrocardiograms helps identify cases of the disorder despite a wide range of findings that may mimic other conditions. Major advances in the efficacy of surgical procedures to cure this syndrome make this a reasonable alternative to life-long medical therapy for many patients. Unfortunately, available diagnostic tests lack the positive predictive value to reliably distinguish patients at risk of sudden death. This review is an update for general internists of the major developments in the evaluation and treatment of the disorder and provides specific examples helpful in differentiating these patients.

[Wolff-Parkinson-White syndrome. Value of intravenous flecainide for detecting Kent's pathways with short refractory period]

The aim of this study was to assess the value of a non-invasive test in detecting accessory pathways with short anterograde effective refractory periods (AERP) (less than or equal to 270 ms) in patients with the Wolff-Parkinson-White syndrome. An intravenous injection of Flecainide acetate was administered to 19 consecutive patients referred for electrophysiological investigation of a WPW syndrome with permanent pre-excitation of the surface electrocardiogram. The first 8 patients (Group I) received a dose of 1.5 mg/kg over 5 minutes and the following 11 patients (Group II) were given 2 mg/kg in 5 minutes. In Group I, preexcitation disappeared in 3 patients (37.5%) who all had accessory pathways with AERP greater than 270 ms. It persisted in the other 5 patients (62.5%) of whom 4 had AERP less than or equal to 270 ms and 1 an AERP greater than 270 ms (false negative). In Group II, preexcitation disappeared in 8 patients (72.2%) of whom 4 had AERP greater than 270 ms and 4 had AERP less than 270 ms (false positives). Preexcitation persisted in the 3 other patients (27.3%); the AERP was less than or equal to 270 ms in 2 patients and greater than 270 ms in the other patients. These results suggest that intravenous Flecainide acetate at the dose of 1.5 mg/kg could be useful in differentiating WPW syndromes with long refractory periods (greater than 270 ms) from those with short refractory periods (less than or equal to 270 ms) with a satisfactory sensitivity and specificity, and that further studies on larger numbers of patients are required to confirm this hypothesis.

[The association of ventricular pre-excitation--acute myocardial infarct. The dysrhythmic outcomes]

The clinical manifestations of ventricular preexcitation, generally considered benign, may sometimes show the most unpredictable and severe evolution. Although ventricular tachyarrhythmias (those of ventricular aspect excepted) are extremely uncommon in ventricular preexcitation, cases of sudden death were nevertheless reported, their mechanism being the ventricular fibrillation. The authors have followed up the evolution of 12 patients (11 males, age between 38 and 72 years with a mean of 56 years) with acute myocardial infarction and coexistent ventricular preexcitation, previously depressed or newly detected, admitted during the last 10 years at the Coronary Unit of Iaşi. It is concluded that the association ventricular preexcitation--acute myocardial infarction represents a severe risk factor by sensibly increasing the arrhythmogenic potential.