Usefulness of vectorcardiography combined with His bundle recordings and cardiac pacing in evaluation of the preexcitation (Wolff-Parkinson-White) syndrome

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.

Arrival of excitation at the left ventricular apical endocardium in Wolff-Parkinson-White syndrome type B

Electrograms were recorded from the His bundle area, right ventricular apex, right ventricular inflow tract, and left ventricular apical endocardium in four patients (aged, 1, 1, 1.5, and 16 years) with Wolff-Parkinson-White syndrome type B. In beats without preexcitation: (a) delayed activation of the right ventricular inflow tract reflected the occurrence of a conduction disturbance through the "distal" or "peripheral" ramifications of the right bundle branch; and (b) the slightly earlier activation of the left ventricular apical endocardium (in reference to the right ventricular apex) may have been due to an earlier emergence from the divisions of the left bundle branch, presumably due to the greater length of the right bundle branch. In beats with preexcitation: (a) the "incomplete" right bundle branch block pattern was concealed because the right ventricular inflow tract was activated before the right ventricular apex; (b) the delta-right ventricular apical intervals were shorter than those of adults with Wolff-Parkinson-White type B; and (c) arrival of excitation at the left ventricular endocardium was a function, either of the impulse emerging from the left bundle branch, or of that propagating from the preexcited site. Therefore, the delta-left ventricular apical endocardial intervals were considered to have represented conduction time from preexcited region to endocardium of left ventricle only when it could be proven that the conduction time (from atrial site of origin to left ventricular apical endocardium) was shorter through the right sided accessory pathway than through the normal pathway. This study suggests that some beats, which may be interpreted as representing "pure" Wolff-Parkinson-White type B complexes from epicardial maps, may in reality be "fusion" complexes.

Wolff-Parkinson-White syndrome type B with tachycardia-dependent (phase 3) block in the accessory pathway and in left bundle-branch coexisting with rate-unrelated right bundle-branch block

A patient with Wolff-Parkinson-White syndrome type B developed 2:1 atrioventricular block resulting from the association of persistent right bundle-branch block with tachycardia-dependent (phase 3) left bundle-branch block. Electrophysiological studies disclosed the coexistence of a tachycardia-dependent (phase 3) block in the accessory pathway. This conduction disturbance was exposed, not by carotid sinus massage as in previous studies, but by pacing-induced prolongation of the interval between two consecutively conducted atrial impulses. Furthermore, the surface electrocardiogram showed, at different times, ventricular complexes resulting from: (1) exclusive atrioventricular conduction through the normal pathway without bundle-branch block; (2) predominant, or exclusive, atrioventricular conduction through a right-sided accessory pathway; (3) exclusive atrioventricular conduction through the normal pathway with right bundle-branch block; (4) exclusive conduction through the normal pathway, with left bundle-branch block; (5) fusion between (1) and (2); and finally, (6) fusion between (2) and (3) However, QRS complexes resulting from simultaneously occurring Wolff-Parkinson-White syndrome type B and left bundle-branch block could not be identified. Future electrophysiological investigations should re-evaluate the criteria used to diffrentiate between true and false patterns of Wolff-Parkinson-White syndrome type B coexisting with left bundle-branch block.

Body surface and intracardiac recordings in a patient with Wolff-Parkinson-White syndrome (type A) with complete infra-His bundle block

Electrocardiograms, vectorcardiograms and His bundle electrograms were recorded in a patient with Wolff-Parkinson-White syndrome (type A) who developed complete infra-Hisian block and advanced A-V block in the Kent bundle. The atrial impulses reaching the ventricles exclusively through the Kent bundle produced QRS complexes and vector loops showing diffuse (leftward initial and rightward pre-terminal) delays and slurrings. These abnormalities were not due to Wolff-Parkinson-White type A coexisting with right bundle branch block, but reflected the activation sequence characteristic of arrival of excitation; spontaneous impulse formation; or electrical stimulation, at the postero-superior wall of the left ventricle. Intracardiac recordings were a complement to body surface recordings in the study of Wolff-Parkinson-White syndrome complicated by A-V conduction disturbances.

Advances in clinical vectorcardiography

With use of the Frank lead system, still loop and timed vectorcardiograms were recorded in more than 5,000 patients sujected to complete right and left hear catheterization and selective coronary cine angiography. Data so obtianed demonstrated clincila superiority of the vectorcardiogram over the standard 12 lead scalar electrocardiogram. Specific advantages of the vectorcardiogram include (1) recognititin of undetected atrial and ventrcular hypertropy, (2) greater sensitivity in identification of myocardial infaraction, and (3) superior capability for diagnosis of multiple infaractions in the presnece of fascicular and burnany number of simultaneously recoreded electrocardiographic leadsfor the analysis of complex arrhythmias and beat to beat changes in intraventricula conduction. SINCE THE VALIDITY AND USEFULNESS OF THIS TECHNIQUE HAVE BEEN ESTABLISHED, IT SHOULD BECOME PART OF THE ROUTINE NONINVASIVE EVALUATION OF PATIENTS WITH CARDIOVASCULAR DISORDERS.