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Case reportsBritish Heart Journal, 1975, 37, 767-770.
Intra-A-type variation ofWPW syndrome
Juhani Heikkila and Antti JounelaFrom the Cardiovascular Laboratory, First Department of Medicine, University Central Hospital, and MariaHospital, Helsinki, Finland
A patient with type A WPW syndrome and variation in the QRS morphology is described.
The WPW syndrome has been traditionally dividedinto two major types, though on the basis of themodem electrophysiological research this classi-fication is becoming of less value. These types havebeen designated as type A and type B, dependingon the orientation of the vector of the initial delta-wave in lead Vi (Rosenbaum et al., I945). Variationbetween the A and B type conductions has beendescribed in the same individuals (Matter andHayes, I964; Ramachandran, I972; Lunel, I972).However, remarkable variation of conduction seemsalso to be possible within a single major WPW typeand during unchanged sinus rhythm, in addition tothe well-known 'concertina effect' seen in tachy-arrhythmias.An intra-A-type variation of WPW syndrome
occurred in an otherwise healthy man described inthis report. The variant type was transiently presentonly after treatment of a paroxysm of fast atrialfibrillation with electrical cardioversion. This kindof striking variation of the QRS morphology in thestandard leads, which initially focused our interest,does not appear to have been reported earlier.
Case reportClinical courseThe patient was a 22-year-old man who had sufferedfrom occasional short attacks of rapid pulse in his child-hood, but was otherwise healthy. He was admitted toanother hospital because of chest pain which followed asudden onset of rapid irregular heart beat. Thesesymptoms had appeared when climbing upstairs. Onadmission his general condition was good. No signs ofcardiac failure were present, the arterial blood pressuremeasured I40/80 mmHg (i8.6/io.6 kPa), and the pulserate was irregular, 140 tO ISo beats/min, but showed aconspicuous pulse deficit. A presumptive diagnosis ofventricular tachycardia was made, however, and ligno-
caine was administered as a loading dose of ioo mg i.v.,followed by a continuous i.v. drip (2 mg/min). Since noeffect was observed during several hours, successfulelectrical conversion was made with ioo J synchronizeddirect current. Propranolol 20 mg four times daily waslater given as a prophylactic antiarrhythmic treatment,when the WPW syndrome was established as a cause ofthe tachyarrhythmias. With this treatment the patienthas been completely free of bouts of tachycardia.
ElectrocardiogramsA) Admission The i2-lead electrocardiogram re-corded on admission displays an irregular tachycardiawith the ventricular rate varying between 200 and 250beats per minute (Fig. i). The QRS complexes arepredominantly widened to O.I2 s and mostly of the sameconfiguration. The activation front is directed to theright (AQRSf + 2000) in both the frontal and horizontalplanes. The major forces are thus directed anteriorly,superiorly, and rightward. The electrocardiogram maythus be explained as a fast atrial fibrillation and ab-normal ventricular conduction with its starting point inthe posterolateral region of the ventricles. However, inleads III, V2, and V5 there are a few QRS complexesin a series of 2 tO 5 which have quite narrow deflectionsof o.o8 s, appearing at a rate of I85 a minute. In fact,such QRS complexes of normal width never occurredlater during sinus rhythm. While of normal width andof normal general shape, these transient beats showedminor terminal delays of activation.
B) After electrical cardioversion (Fig. 2, p. 768)The rhythm restored with a single I00 J shock showssinus tachycardia. The PQ interval is 0.13 s and QRSduration 0.12-0.13 s. The P wave does not show anyvariation in its shape. The major ventricular activationforces are directed in the frontal plane upwards (-80o)turning then to the left, and in the horizontal planeanteriorly (+ I00°). The delta wave of the WPWpattern is clearly visible in both planes, being positive
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768 Heikkila and Jounela
ECG ON ADMISSION. FAST ATRIAL FIBRILLATION AND W-P-WCONDUCTION ALTERNATING WITH NORMAL QRS COMPLEXES
3_tn >9 \-a e 1~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
K* \ ..i .~V2
]j~~~~~~JU
VsFOUR HOURS LATER.THE THREE COMPLEXES AT SLOWER RATEARE OF SIMILAR W-P-W PATTERN AS AFTER REVERSAL
aVR i E ra
FIG. I Electrocardiogram recorded on admission.
from Vi to V5 but inconspicuous in V6. In the frontalplane the delta wave orientates upwards and slightlyleftwards. Thus the initial activation focus would besituated in the posterior regions of the heart.
C) Basic electrocardiogram (Fig. 2, bottom). Theelectrocardiogram recorded next day is similar to alllater control records during the next 6 months. The P
ECG FOLLOWING CARDOVERSION SHOWS TYPE A W-PW
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2
OPPOSITE DIRECTION IN THE FRONTAL PLANE4 r ?
WSF --
Vs_rY8 1,
FIG. 2 The serial electrocardiograms reveal anintra-A-type variation of Wolff-Parkinson-White syndrome.
wave is again similar to that in the immediate post-conversion rhythm. The PQ interval is now slightlyshorter and QRS broader, i.e. O.II and 0.I3-0.14 s. Themain QRS vector is directed in the frontal plane roughlyopposite to that of the postconversion time. The AQRSfis between + 600 and + 700 both for the delta wave andalso for the main forces. In the horizontal plane, themain forces are similar to those seen before in the prae-cordial leads, showing minor variations only. Thoughthe delta wave is positive again from Vi to V5 as before,there are two differences. Now the delta wave in V6 isalso positive and also the delta waves are clearly broader.Thus, the initial activation focus would be located againin posterior basal regions, though with a slightly dif-ferent insertion of the accessory pathway.
DiscussionIn spite of the striking differences of the QRS com-plexes noted in the limb leads, both the electro-cardiogram recorded after cardioversion (B) andthat representing the basic rhythm (C) complywith the criteria of the major type A WPW syn-drome. Changes in the main QRS vector in WPWsyndrome (in the present patient in opposite direc-tions in the frontal plane) are known to occur duringthe transition from sinus rhythm to atrioventricularrhythm. Moreover, it has been stressed that there isa high frequency of supraventricular ectopic fociin patients with pre-excitation syndrome (Sherf andJames, I969; Hindman, Last, and Rosen, I973).This seems, however, not to be a likely explanationof the present case since the shape and size of the Pwaves are exactly the same in both electrocardio-grams.The most probable explanation of the electro-
cardiographic findings described above would be
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Intra-A-type variation of WPW syndrome 769
the presence of two bypassing Kent type bundlesnear each other in posterolateral regions of the leftventricle. This conclusion is supported by both thevector analysis of the initial force as well as by theactivation patterns documented by Boineau et al.(I973) in their thorough analysis of WPW conduc-tion. It is also possible that one Kent bundle isaccompanied by one septal Mahaim bundle (B),besides the normal atrioventricular node. Recenthistological examinations of the heart in the WPWsyndrome have revealed a sound anatomical basisfor the occurrence of several accessory atrioven-tricular myocardial fibres, transversing gaps in adiscontinuous annulus fibrosus (Lunel, I972). Thisfinding is nicely supported by direct mapping of theactivation wave fronts on the epicardium (Boineauet al., I973). It is suggested that these Kent typefibres transmit impulses varyingly and thus are acause of the A and B type variation in ventricularactivation. The James-Mahaim hypothesis has sofar remained less firmly documented (Moore, Spear,and Boineau, I973).
Boineau and his co-workers (I973) have recentlyre-examined the electrocardiographic typing indif-ferent insertions of the anomalous connexion. Theyrelated the standard I2-lead electrocardiograms tothe recorded mapping of activation sequences on thesurface of the heart. According to their data electro-cardiogram C ofour patient would best resemble thetype 4 in their model, i.e. lateral left ventricular pre-excitation, and electrocardiogram B again faithfullyresembles type 3, a more posterior insertion. Not-ably, both these two possible Kent bundle locations3 and 4 are in the posterolateral region, as deducedtoo by means of the vector analysis in our patient.They too show similar V-lead type A complexes buthave opposite directions of activation in the frontalplane.That the cause of the varying frontal plane QRS
axis is related to different posterolateral accessorypathways close to each other has not been estab-lished. The posterior insertion of the bypass tract(electrocardiogram B, type 3), results in epicardialbreakthrough at the posterior atrioventricular marginon the left side of the septum. The activation ofthese inferior areas is also first to be completed,before that of the anterior and superior regions. Thepre-excitation impulse may be thought also to invadethe posterior fascicle of the left bundle-branch,resulting in its early retrograde activation. In anycase large posteroinferior muscle masses are theearliest areas activated, with a consequent left axisdeviation caused by large superiorly oriented forces.In a more lateral insertion (electrocardiogram C,type 4) the frontal plane axis remains normal; furtherthe anomalously activated muscle areas tend to
remain smaller, perhaps without retrograde bundle-branch activation. The slight differences in the PQand QRS durations in our patient are in fact oppositefrom those that might be expected, because lateralactivation is usually more delayed and produces lesspre-excitation than the medial sites (Boineau et al.,I973). These assumptions based on the time inter-vals alone, however, may be misleading if conduc-tion velocities of different tracts have been alteredfor instance by the drug treatment.The few normal-shaped QRS complexes ob-
served during the tachyarrhythmia may represent atemporary complete failure of both accessory tractscaused by excessive firing because of atrial fibrilla-tion. In fact, sudden Mobitz 2 type block best char-acterizes the electrophysiological properties of theanomalous connexion (Roelandt et al., 1973). Thisallows normal conduction through the atrioven-tricular node. Similarly, the QRS morphology dom-inating during the tachyarrhythmia may result fromvarying ventricular conduction.
Cardioversion and/or antiarrhythmic drugs mayhave blocked one of the accessory tracts, i.e. thatwhich dominates in mediating the basic rhythm.Different refractory times of the tracts may havecaused the temporary finding seen in electrocardio-gram B. For instance, lignocaine depresses bothmuscle conduction and atrioventricular node in vary-ing degrees. The above possibilities in generatingvariable conduction are further supported by findingthat the different Kent bundles differ remarkably intheir conductivity in the atrial pacing tests (Mooreet al., 1973).To our knowledge, this kind of variation of ven-
tricular activation within one major type of WPWsyndrome has not been reported earlier. It need notbe rare, however, as suggested by the recent histo-logical evidence of adjacent Kent type fibres locatedin gaps in the annulus fibrosus. Continuous moni-toring of patients during tachyarrhythmias andimmediately thereafter may show that shifts fromone 'subtype' to another are more common than isbelieved.
ReferencesBoineau, J. P., Moore, E. N., Spear, J. F., and Sealy, W. C.
(1973). Basis of clinical-ECG variations in right and leftventricular pre-excitation: a unitary concept of WPW. InCardiac Arrhythmias, p. 42I. Ed. by L. S. Dreifus andW. Likoff. Grune and Stratton, Philadelphia.
Hindman, M. C., Last, J. H., and Rosen, K. M. (I973).Wolff-Parkinson-White syndrome observed by portablemonitoring. Annals of Internal Medicine, 79, 654.
Lunel, A. A. V. (I972). Significance of annulus fibrosus ofheart in relation to AV conduction and ventricular activa-tion in cases of Wolff-Parkinson-White syndrome. BritishHeart Journal, 34, 1263.
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Matter, B. J., and Hayes, W. L. (1964). Wolff-Parkinson-White syndrome. Report of a case with both type A andtype B pre-excitation. American Journal of Cardiology, 13,284.
Moore, E. N., Spear, J. F., and Boineau, J. P. (I973). Recentelectrophysiologic studies on the Wolff-Parkinson-Whitesyndrome. New England Journal of Medicine, 289, 956.
Ramachandran, S. (1972). Wolff-Parkinson-White syndrome.Conversion of type A to type B electrocardiographicchanges. Circulation, 45, 529.
Roelandt, J., Schamroth, L., Draulans, J., and Hugenholtz,P. G. (I973). Functional characteristics of the Wolff-Parkinson-White bypass. A study of six patients with Hisbundle electrograms. American Heart Journal, 85, 260.
Rosenbaum, F. F., Hecht, H. H., Wilson, F. N., and Johnston,F. D. (1945). The potential variations of the thorax andthe esophagus in anomalous atrioventricular excitation(Wolff-Parkinson-White syndrome). American HeartJ'ournal, 29, 28I.
Sherf, L., and James, T. N. (i969). A new electrocardio-graphic concept: synchronized sinoventricular conduction.Diseases of the Chest, 55, I27.
Requests for reprints to Dr. Juhani Heikkila, Cardio-vascular Laboratory, University Central Hospital, 00290Helsinki 29, Finland.
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