Classification of ventricular pre-excitation. Vectorcardiographic study

Value of the resting 12 lead electrocardiogram and vectorcardiogram for locating the accessory pathway in patients with the Wolff-Parkinson-White syndrome

The resting 12 lead electrocardiogram and vectocardiogram were reviewed in 47 patients with the Wolff-Parkinson-White syndrome (a) who had pre-excitation on the resting 12 lead electrocardiogram, (b) who had a single anterograde conducting accessory pathway assessed and located during preoperative electrophysiological study and during epicardial mapping at operation, and (c) in whom surgical division of the accessory pathway resulted in loss of pre-excitation. The site of the accessory pathway established during operation was compared with that established by evaluating the polarity of the delta wave and QRS complex on the resting 12 lead electrocardiogram. The electrocardiogram was assessed by the Rosenbaum criteria (Wolff-Parkinson-White type A, left-sided pathway; or type B, right-sided pathway), the Gallagher criteria (atrial pacing resulting in maximal pre-excitation), and the World Health Organisation criteria (a composite of previous studies). The Gallagher and World Health Organisation criteria were derived from patients demonstrating maximal pre-excitation that often required atrial pacing. The present study was designed to determine whether these criteria could be accurately applied to the resting 12 lead electrocardiogram on which the degree of pre-excitation was variable. The Rosenbaum criteria correctly identified a left sided accessory pathway in 26 of 34 patients and a right-sided accessory pathway in nine of 13 patients. The Gallagher and World Health Organisation criteria correctly identified the location in only 15 (32%) of the 47 patients. The resting vectorcardiogram was inaccurate for locating the accessory pathway. Although published criteria are useful for identifying the site of the accessory pathway from an electrocardiogram obtained when rapid atrial pacing is being used to achieve maximal pre-excitation, they are not suitable for identifying the exact site of an accessory pathway from the resting 12 lead electrocardiogram.

Wolff-Parkinson-White VCG patterns that mimic other cardiac pathologies: a correlative study with the preexcitation pathway localization

Vectorcardiograms (VCGs) of 44 patients with a Wolff-Parkinson-White (WPW) syndrome have been analyzed with the aim to correlate the QRS loop patterns with specific preexcitation sites. The VCG QRS loops were analyzed to determine whether conduction abnormalities and myocardial infarction (MI)-like patterns observed in the WPW syndrome could be related to specific preexcitation sites identified by surgery as well as by body surface potential mapping (BSPM). Left bundle branch block pattern was observed with anteroseptal (AS) preexcitation, anterior MI pattern was seen with lateral right ventricle (LRV) preexcitation, left anterior fascicular block was observed with posterior right ventricle (PRV) preexcitation, inferoposterior and strictly posterior MI pattern was found with posteroseptal (PS) and posterior left ventricle (PLV) preexcitation, right bundle branch block was seen in lateral left ventricle (LLV) preexcitation, and right bundle branch block was observed with left posterior fascicular block in anterior left ventricle (ALV) preexcitation. These VCG criteria seem to identify accurately the preexcitation sites as observed by delta wave BSPM and at surgery investigations. Consequently, they could be useful in localizing the preexcitation site in cases of ambiguous delta vector orientation.

A quantitative method for the localization of the ventricular pre-excitation area in the Wolff-Parkinson-White syndrome using singular value decomposition of body surface potentials

In order to localize quantitatively the site of ventricular pre-excitation, singular value decomposition (SVD) was applied to the body surface potential distributions of patients with the Wolff-Parkinson-White syndrome. The body surface potentials of sixty-two patients were recorded during sinus rhythm and pre-excitation by means of thirty electrodes placed on the anterior thoracic wall. The sites of the anomalous bundles had been determined beforehand by multicatheter electrophysiologic study. Considerable data reduction was obtained by using the SVD technique and displaying the potential distribution during the delta wave on two isofunction maps of the first two positional vectors and their corresponding two singular values (SV). A distinction was made between two types of isofunction maps. A type-S (single extreme) and a type-D (double extremes). A quantitative analysis was performed with the orientation of the zero line on the isofunction map being represented by the angle alpha or beta, and the singular values quotient (SVQ) of the two first singular values. The angle beta belonging to type D was used to subdivide this group of pre-excitation areas. The parameters SVQ and alpha belonging to type-S were illustrated in a graph on which a distinction between the various locations of the pre-excitation areas can be seen.

Body surface potential distributions in posterior ventricular pre-excitation

Waveform of the QRS complex during ventricular pre-excitation is subject to the influence of both the site of pre-excitation and the time of pre-excitation relative to that of excitation via the normal AV path. This paper reports a case in which lead V1 of the electrocardiogram (ECG) could be altered from an R to an rS pattern by the administration of atropine sulfate. The provable mechanism was that of reduced conduction time in the normal AV path with altered time phase of normal excitation and pre-excitation. This mechanism was simulated in experiments on dogs and yielded similar findings. Body surface mapping in both the patient and the dogs provided evidence that pre-excitation could be recognized by that means with varied time phase of normal excitation and pre-excitation. It was demonstrated that the QRS complex of right sided precordial leads could be altered from an R to an rS pattern by altering the time phase of normal excitation and pre-excitation of the posterior ventricular wall. This alteration was related to the degree to which negative potentials on the anterior chest wall due to right ventricular breakthrough of normal activation developed in relation to the time of pre-excitation.

Body-surface maps of heart potentials: tentative localization of pre-excited areas in forty-two Wolff-Parkinson-White patients

Heart potentials were recorded from the entire chest surface in 42 patients suffering from Wolff-Parkinson-White syndrome. We were able to identify six types of surface maps, according to the location of the potential maximum and minimum during the delta wave. For each of these types we suggested the most likely location of the pre-excited region around the A-V rings (types 1 to 5) or in the interventricular septum (type 6). In 13 patients belonging to Types 1, 2, 3, 5 and 6 our hypotheses were in agreement with intracardiac recordings, epicardial maps or surgical results obtained by others. Isopotential surface maps provide more information on the location of the pre-excited area than conventional ECGs, particularly when these exhibit intermediate features between Types A and B.

Initial forces of ventricular depolarization in the Wolff-Parkinson-White Syndrome. Analysis based upon localization of the accessory pathway by epicardial mapping

The epicardial activation sequence of 34 patients with the Wolff-Parkinson-White syndrome was determined. Epicardial pre-excitation occurred at a spectrum of sites over either the free wall of the left or right ventricle or in a paraseptal region, always adjacent to the atrioventricular rings. The site of pre-excitation was related to the spatial position of the 10 msec vector of the vectorcardiogram (VCG) in 15 patients and the 20 msec vector of the electrocardiogram (ECG) in 29 patients with a single accessory pathway. All patients whose 20 msec vector (ECG) was directed to the right had accessory pathways which caused epicardial breakthrough over the free wall of the left ventricle. When the 20 msec vector (ECG) was to the left and inferior, epicardial pre-excitation was over either the right ventricular free wall or in the region of the pulmonary outflow tract. Superior location of the initial forces, especially the 10 msec vector (VCG), strongly suggested the presence of a septal bypass tract. The polarity of the delta wave and maximum QRS forces in precordial lead V1 were discordant in a significant number of patients, pointing to probable shortcomings of a classification based upon the latter.