THE SYNDROME OF SHORT P-R INTERVAL, APPARENT BUNDLE BRANCH BLOCK, AND ASSOCIATED PAROXYSMAL TACHYCARDIA

History of Wolff-Parkinson-White syndrome

While Drs. Wolff, Parkinson, and White fully described the syndrome that bears their names in 1930, prior case reports had already described the essentials. Over the ensuing century this syndrome has captivated the interest of anatomists, clinical cardiologists, and cardiac surgeons. Stanley Kent described lateral muscular connections over the atrioventricular (AV) groove, which he felt were the normal AV connections. The normal AV connections were, however, clearly described by His and Tawara. True right-sided AV connections were initially described by Wood et al., while Ohnell first described left free wall pathways. David Scherf is thought to be the first to describe our current understanding of the pathogenesis of the Wolff-Parkinson-White (WPW) syndrome in terms of a reentrant circuit involving both the AV node--His axis as well as the accessory pathway. This hypothesis was not universally accepted and many theories were applied to explain the clinical findings. The basics of our understandings were established by the brilliant work of Pick, Langendorf, and Katz who by using careful deductive analysis of ECGs were able to define the basic pathophysiological processes. Subsequently, Wellens and Durrer applied invasive electrical stimulation to the heart in order to confirm the pathophysiological processes. Sealy and his colleagues at Duke University Medical Center were the first to successfully surgically divide an accessory pathway and ushered in the modern area for curative therapy for these patients. Morady and Scheinman were the first to successfully ablate an accessory pathway (posteroseptal) using high-energy direct-current shocks. Subsequently, Jackman, Kuck, Morady, and a number of groups proved the remarkable safety and efficiency of catheter ablation for pathways in all locations using radiofrequency energy. More recently, Gallob et al. first described the gene responsible for a familial form of WPW. The current ability to cure patients with WPW is due to the splendid contributions of individuals from diverse disciplines from throughout the world.

Familial occurrence of accessory atrioventricular pathways (preexcitation syndrome)

Accessory atrioventricular pathways, the anatomical structures responsible for the preexcitation syndromes, may result from a developmental failure to eradicate the remnants of the atrioventricular connections present during cardiogenesis. To study whether preexcitation syndromes could also be transmitted genetically, we determined the prevalence of preexcitation in the first-degree relatives of 383 of 456 consecutive patients (84 percent) with electrophysiologically proved accessory pathways. We compared the observed prevalence of preexcitation among the 2343 first-degree relatives with the frequency reported in the general population (0.15 percent). For 13 of the 383 index patients (3.4 percent), accessory pathways were documented in one or more first-degree relatives. At least 13 of the 2343 relatives identified (0.55 percent) had preexcitation; this prevalence was significantly higher than that in the general population (P less than 0.0001). Identification of affected relatives may have been incomplete because clinical information was obtained only about symptomatic relatives. Patients with familial preexcitation have a higher incidence of multiple accessory pathways and possibly an increased risk of sudden cardiac death. Our data suggest a hereditary contribution to the development of accessory pathways in humans. The pattern of inheritance appears to be autosomal dominant.

The electrophysiologic effects of intravenous lidocaine in the Wolff-Parkinson-White syndrome

Twelve patients with the Wolff-Parkinson-White syndrome underwent electrophysiologic study, before and after the bolus intravenous administration of lidocaine, 1 mg./kg. There was no significant increase in the effective refractory period of the anterograde AV node pathway, the anterograde or retrograde accessory pathway, or the atrial or ventricular muscle; intravenous bolus administration of lidocaine is unlikely to terminate the re-entry tachycardias, or decrease the rate of the ventricular response in atrial fibrillation, in the WPW syndrome. There was no significant increase in the anterograde or retrograde AV conduction times; bolus administration of lidocaine is unlikely to decrease the rates of the re-entry tachycardias. In addition, lidocaine failed to alter significantly features related to tachycardia initiation. Except in isolated, unpredictable cases, intravenous bolus administration of lidocaine is not likely to be of benefit in the supraventricular tachyarrhythmias of the WPW syndrome.

Atrial fibrillation in the preexcitation syndrome

One hundred patients with proved accessory pathways of the Kent bundle type were studied with multiple intracardiac catheters. During the procedure 16 had atrial fibrillation. Two patterns of induction of atrial fibrillation were noted. In most patients an earlier than expected atrial deflection appeared in one of the atrial recordings and was followed by atrial flutter (cycle length less than 220 msec) or atrial fibrillation either immediately or after a brief period of acceleration of atrial rate. In a few patients, intraatrial conduction delay, manifested as 2:1 block or Wenckebach block from the right to the left atrium or vice versa, occurred before the onset of atrial fibrillation. The incidence of atrial fibrillation was not statistically related to any associated cardiac abnormalities. A significantly large incidence of ventricular fibrillation was recorded in patients who had documented atrial fibrillation either before admission or during the catheter study.

Wolff-Parkinson-White Syndrome. A review

Recent developments in the field of electrophysiology and surgical therapy in selected cases of Wolff-Parkinson-White syndrome (W-P-W) support the concept of anomalous A-V pathways. Impulse transmission usually occurs simultaneously through both the normal and anomalous pathways resulting in a fusion QRS complex. Atrial tachycardia is usually due to reentry through the normal and anomalous A-V pathways. However, reentry may occur independently in the A-V node alone exclusive of the anomalous pathway. Anomalous connections, despite varying anatomic locations, may result in similar electrocardiographic manifestations characteristic of W-P-W. His bundle recordings together with electrophysiologic studies may be clinically useful (1) to differentiate various types of anomalous connections, (2) for possible determination of the reentry circuit, (3) to predict the maximum ventricular rate possible during supraventricular tachycardia by evaluating the refractory period of the A-V pathways, or (4) to compare the efficacy of different drugs in a given patient. Surgical interruption of the anomalous pathway in selected cases with W-P-W (type B) is feasible but is most commonly not necessary. The indications for medical and surgical management of symptomatic cases with W-P-W are reviewed.

Successful surgical interruption of the bundle of Kent in a patient with Wolff-Parkinson-White syndrome

Recurrent supraventricular tachycardia is a frequent complication in patients with the Wolff-Parkinson-White (WPW) syndrome. Our patient was unusual in that the arrhythmia was the predominant rhythm, and it was felt that the sustained tachycardia was responsible for signs and symptoms of congestive heart failure. The arrhythmia could not be controlled adequately with digitalis, quinidine, diphenylhydantoin, or propranolol. Atrial or ventricular pacing also failed to prevent recurrent episodes of tachycardia.

Physiological and pharmacological studies suggested that an anomalous pathway was responsible for the WPW abnormality and participated in a re-entrant circuit which sustained the episodes of tachycardia. Isopotential body surface mapping suggested anomalous ventricular excitation at the lateral aspect of the right atrioventricular groove. Epicardial mapping at the time of surgery was used to localize the earliest area of anomalous ventricular activation, and surgical transection of the atrioventricular junction at that point abolished the electrocardiographic features of WPW and the recurrent tachycardia. Five months after surgery neither the ECG features of WPW nor the tachycardia has recurred. The signs and symptoms of congestive heart failure have subsided, and the patient has returned to work.

The Syndrome of Short P-R Interval Normal QRS Complex and Paroxysmal Rapid Heart Action

A short A-V conduction time, whether present with normal or with abnormal QRS complex, is associated with an increased incidence of paroxysmal rapid heart action. There are a considerable number of patients who have a short P-R interval, normal QRS complex and bouts of tachycardia. They are usually females, in middle life, devoid of organic heart disease and exhibit a snapping apical first heart sound. They do not demonstrate any of the features of anomalous A-V conduction. Evidence is presented suggesting the operation of endocrine and autonomic nervous system factors in the genesis both of the short P-R interval and the tachycardia.

Ventricular Tachycardia during Cardiac Catheterization of Patient with Wolff-Parkinson-White Syndrome

Cardiac catheterization of a patient with probable Wolff-Parkinson-White syndrome was attempted to clarify the possibility of coexistent congenital heart disease. Introduction of the catheter into the heart induced a multifocal ventricular tachycardia which endangered the life of the patient. After quinidine and other drugs had failed to control the arrhythmia that persisted for nine hours, a prompt and gratifying conversion to supraventricular tachycardia, and subsequently to sinus rhythm, followed the intravenous administration of atropine sulfate.

Intracardiac and Intravascular Potentials Resulting from Electrical Activity of the Normal Human Heart

Electrical records were made from the interior of the right heart and attached vessels in 14 normal subjects. Technics differed somewhat from those previously reported in that simultaneously recording string galvanometers were used exclusively, and tracings were made whenever the catheter-electrode was moved within the heart. Previously unreported large positive QRS deflections were found in records from the lower part of the right atrium, from the pulmonary artery, and in two instances from within the right ventricle itself close to the base. The possible anatomical origin of these is discussed.

Occurrence of the Wolff-Parkinson-White syndrome concomitant with acute rheumatic fever

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Wolff-Parkinson-White Syndrome (Short P-R Intervals Associated With Disturbances of Intraventricular Conduction) With Attacks of Paroxysmal Tachycardia in an Infant Aged 8 Months Suffering From Probable Congenital Heart Disease

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THE GENESIS OF THE NORMAL ELECTROCARDIOGRAM

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