Br J: first published as 10.1136/hrt.43.4.481 on 1 April 1980. Downloaded from

Case reports

Br HeartJ 1980; 43: 481-6

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

IVAN J MENDOZA, AGUSTIN CASTELLANOS, RUEY J SUNG From the Division of , Department of Medicine, University of Miami School of Medicine, Miami, Florida, USA suMMARY A patient with Wolff-Parkinson-White syndrome type B developed 2:1 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 tachy- cardia-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 conduc- tion through the normal pathway without bundle-branch block; (2) predominant, or exclusive, atrio- ventricular conduction through a right-sided accessory pathway; (3) exclusive atrioventricular conduction http://heart.bmj.com/ 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 in- vestigations should re-evaluate the criteria used to differentiate between true and false patterns of

Wolff-Parkinson-White syndrome type B coexisting with left bundle-branch block. on September 26, 2021 by guest. Protected copyright.

The association of Wolff-Parkinson-White (WPW) bundle-branch block, but exclusively when the syndrome, either type A or type B, with right sinus cycle lengths were shorter than 620 ms, that bundle-branch block has been well recognised.'-7 is when the rates were over 96/min (Fig. IA). However, there are far fewer reports of the co- On the other hand, WPW type B was seen only existence of left bundle-branch block with pre- with longer sinus cycle lengths. For example, Fig. excitation.1 2 8-13 Even more rare is the occurrence 1B and C recorded while the rates ranged between of both right and left bundle-branch block in a 79 and 86/min show that the PR intervals were patient with WPW type B. short (120 ms), the QRS complexes wide and of varying duration (100 to 130 ms), and the electrical Case report axis deviated abnormally to the left (about -60°). Finally, Fig. 1D was obtained after pre-excitation A 62-year-old woman with WPW syndrome type B had been abolished by the intravenous administra- and recurrent supraventricular was tion of 600 mg procainamide (given at a rate of referred for electrophysiological evaluation after the 100 mg every five minutes). The sinus rates ranged appearance of right bundle-branch block and 2:1 between 79 and 83/min. The QRS complexes were atrioventricular block. Electrocardiograms during narrow, there being no evidence whatsoever of left previous admissions had also shown pure left bundle-branch block. 481 Br Heart J: first published as 10.1136/hrt.43.4.481 on 1 April 1980. Downloaded from

482 Mendoza, Castellanos, Sung

In Fig. 1, physiological (rate - related) and normal (AV node-His bundle-left bundle- pharmacological variations in the PR intervals branch) pathway. The duration of the corresponding prevented the comparison between the PJ (or PS) AH, HV, and H right ventricular apex (RVA) intervals occurring during left bundle-branch intervals was 110, 50 and 85 to 90 ms, respectively. block, WPW type B, and normal conduction with Since the pre-excitation had become concealed, narrow QRS complexes. Nevertheless, the effects attempts had to be made to expose, or unmask, of procainamide suggested that the pre-excitation atrioventricular conduction through the accessory complexes were fusion beats resulting from ven- pathway (Fig. 2 and 3). This was accomplished by tricular activation through both accessory and increasing the intervals between two consecutively normal pathways (without left bundle-branch block conducted atrial impulses by means of a single in the latter). This assumption implies that the premature atrial stimulus delivered after every patient had a tachycardia-dependent (phase 3) eighth blocked P wave. When these intervals were left bundle-branch block. prolonged beyond 1000 ms, they were terminated Further evidence supporting the existence of a by QRS complexes (last in Fig. 2 and in Fig. 3, rate-related conduction disturbance in the left left panel) which were different from those with a bundle-branch was obtained from intracardiac right bundle-branch block morphology in that: electrophysiological studies performed after de- (a) lead I changed to a predominantly positive velopment of right bundle-branch block. Thus, the deflection (not followed by a wide S wave) with a first half of Fig. 2, recorded while the high right slurring in its upstroke (delta wave); (b) the was paced, shows 2:1 atrioventricular electrical axis was deviated abnormally to the left; block. The first and third P waves, reaching the and (c) lead Vi changed to an Rsr' pattern (Fig. 2) ventricles exclusively through the left bundle- or to an Rs morphology (Fig. 3, left panel). In these branch, were followed 400ms later by P waves complexes AH remained at the control value blocked below the site from which the H deflection (110 ms) but the H deflection was inscribed as the was recorded (presumably at both bundle-branches ventricles started to be depolarised by the impulse simultaneously). emerging from the accessory pathway. In conse- In the beats conducted with a right bundle- quence, the AV interval of 110 ms was used as a

branch block morphology the interval between the rough estimate of conduction time through the http://heart.bmj.com/ atrial (A) deflection of the His bundle electrocardio- accessory pathway.14 15 graphic lead and the onset of ventricular (V) These findings suggested that the last QRS com- depolarisation (wherever it might have occurred) plexes in Fig. 2 and 3, left panel, reflect fusion gave a measure of conduction time through the resulting from ventricular activation through both

I B 111 VI V2 Vs on September 26, 2021 by guest. Protected copyright. A 4E.tU Fig. 1 Tachycardia-dependent block in the left bundle-branch and (possibly) in the accessory B [ U pathway (A); different degrees of pre-excitation with Wolff- Xl- Parkinson-White type B La..LL: morphologies (B, C) and narrow QRS complexes after C procainamide (D). , S4_

D- H:_-jX.--1J Br Heart J: first published as 10.1136/hrt.43.4.481 on 1 April 1980. Downloaded from

Phase 3 block in normal and accessory pathways 483 the accessory and normal pathways (with right the right panel of Fig. 3 (in turn resulting from bundle-branch block in the latter). On the other the concealed penetration, into the atrioven- hand, the last QRS complex in Fig. 3, right panel, tricular node, of the preceding, premature, atrial resulted from exclusive, or almost exclusive, con- beats) produced sufficient delay in the conduction duction through the accessory pathway. It thus of the impulse traversing the normal pathway so as had a morphology similar to that in Fig. 1B. to allow the impulse traversing the accessory path- Whenever pre-excitation occurred, the HV in- way to activate all or most of both ventricles." 15 tervals, as well as the His-right ventricular apex (H-RVA) intervals, were shorter than in control Discussion complexes, indicating that the apex of the right was not activated by the impulse traversing DIFFICULTIES IN DETERMINING LOCATION the normal pathway, but by that emerging from the OF ACCESSORY PATHWAY accessory pathway.'4 16 Therefore, the time elapsing The major problem in diagnosing the location of the between the onset of the delta wave and arrival of accessory pathway in this case was related to the excitation at the RVA (35 ms) was used to estimate occurrence of pre-excitation only at very long cycle conduction time from pre-excitated site to the lengths (Fig. 2 and 3). Nevertheless, analysis of the apex of the right ventricle.'4 15 Moreover, if the surface electrocardiographic and intracardiac elec- AV interval (of 105 ms) preceding the ventri- trophysiological events suggested that the accessory cular complexes with a delta wave indeed reflected pathway was right sided. Vectorial analysis of the conduction time through the accessory pathway, standard and chest leads showed that the abnormal then the fusion complexes in Fig. 2 and 3 can be ventricular depolarisation occurred in a superior, explained by assuming that the corresponding AH leftward, and posterior direction (Fig. 1 to 3). interval of 110 ms still allowed certain portions of Moreover, during maximal pre-excitation the initial the left ventricle to be activated by the impulse slurring was located partly in the left anterior descending through the left bundle-branch."4 1' quadrant and partly in the left posterior quadrant. However, the increase of the AH interval to Even in the absence of spatial vectorcardiograms 140 ms which occurred in the last complex of these findings can be construed to indicate that the

Fig. 2 Intracardiac recordings http://heart.bmj.com/ (obtained during atrial pacing) showing: (a) pure right bundle- 1000 ms branch block (RBBB) in conducted impulses (first two QRS PREMATURE FUSION complexes); (b) 2:1 (infra- RBBB STIMULUS A Hisian) A V block resulting from I the association ofpersistent RBBB -r r with tacycardia-dependent 11 _ (phase 3) left bundle-branch on September 26, 2021 by guest. Protected copyright. ID block (LBBB); (c) tachycardia- F -- dependent (phase 3) block in the accessory pathway; and (d) fusion resulting from the HRA -\: i- coexistence of right bundle-branch block with WPW type B (last MRA -| I A-I- AH QRS complex). Numbers I between arrows refer to the HBE - - , jpI-H',\ interval between two consecutively conducted atrial (A) impulses. A HX A H A H \; A H A A s A H All values are expressed in ms. RVA HRA: high right atrium; MRA: A - (780) - A 4- (1070) ) A mid-right atrium; RVA: right A - H:110 A - H:110 ventricular apex; A: atrial H- V: 50 H- V: 0 electrogram recorded in the His A - V:160 A - V:llO bundle electrogram (HBE) lead; H -RVA: 85-90 H -RVA: 55 V: onset of depolarisation, regardless of the pathway responsible for initial ventricular activation. Br Heart J: first published as 10.1136/hrt.43.4.481 on 1 April 1980. Downloaded from

484 Mendoza, Castellanos, Sung

accessory pathway ended in a right-inferior, not proved as electrophysiological studies were not probably mid-septal, site."6 performed. On the other hand, the intracardiac studies In our opinion the diagnosis of the conduction showed that the estimated conduction time between disturbance under consideration cannot always be the pre-excited site and the right ventricular apex made exclusively from the surface electrocardio- in beats with delta waves (35 ms) was similar to that gram since multiple factors can produce false previously reported in patients with WPW type B patterns of tachycardia-dependent (phase 3) block (40 to 50 ms).'6 These values were significantly in the accessory pathway.2' Foremost among these shorter than those reported in patients with WPW are the differences in conduction time through type A (120 to 160 ms).'4 normal pathway and anomalous pathway. Theoretically, the distance between the ven- Disappearance of pre-excitation at relatively high tricular end of the accessory pathway and the re- rates may simply be an expression of a sympathetic cording electrodes can be determined if the conduc- enhancement of AV nodal conduction without any tion time, conduction velocity, and location of change in the physiological properties of the conduction pathways are known. Unfortunately, accessory pathway. In addition, this phenomenon these indices have not been adequately defined for has also been ascribed to a shift in the site of im- the human ventricles: the reported conduction pulse initiation, to differential intra-atrial delays, times have ranged widely between 440 mm/s (in and to changes in the site and mode of entry into revived ) to 1200 mm/s (in patients with the AV node and accessory pathways.2' 22 Similarly, implanted left ventricular pacemakers).'7 18 In the exposure of pre-excitation during sinuatrial canine hearts Lewis found that the conduction slowing produced by carotid sinus massage20 may velocity through the ordinary muscle of the free be explained entirely by vagal-induced AV nodal right ventricular wall was approximately 400 block of high degree. mm/s.'9 The method used to unmask the pre-excitation Calculations based on these values suggest that in Fig. 2 and 3 was different from that used by the distance between the site of emergence from the Przybylski et al.20 Fig. 2 and 3 also show that the accessory pathway and the right ventricular apex occurrence of pre-excitation at long cycle lengths in our two cases could have ranged between was related to: (a) the duration of the phase 3 block 15 4 and 42 mm. in the accessory pathway; and (b) differences in http://heart.bmj.com/ conduction time through the latter and through TACHYCARDIA-DEPENDENT (PHASE 3) the normal pathway. BLOCK IN ACCESSORY PATHWAY The absence of pre-excitation (before the develop- RIGHT BUNDLE-BRANCH BLOCK IN PATIENTS ment of 2:1 AV block) in all tracings showing sinus WITH WOLFF-PARKINSON-WHITE SYNDROME tachycardia (Fig. 1A) could have been the result of The association of right bundle-branch block with block in the WPW type A, or type B, has been well recognised tachycardia-dependent (phase 3) on September 26, 2021 by guest. Protected copyright. accessory pathway.20 However, this assumption was and thoroughly discussed.'-7

wPW Fig. 3 Atrial pacing with: 1000 ms type RBBB FUSION - B (a) pure right bundle-branch RBBB block in conducted impulses (first QRS complex in the left, and in the right panel); (b) 2:1 I A V block resulting from the association ofpersistent right bundle-branch block and tachycardia-dependent (phase 3) HRA-> t,' aS H -!~~~v block in the accessory pathway; (d) fusion resulting from the MRA- -- ! coexistence of right bundle-branch block with WPW type B (second HBE-.1--\ QRS complex in the leJt panel); H H and (e) ventricular complex K' A -" (1070) 4.. A A +., (Q020) 4-A (last in the right panel) with a A - H:llO A - H:llO A - H:135 pure, or almost pure, WPW H- V: 50 H- V: 0 H after V A - V:160 A - V:llO A - V:llO type B morphology. H - RVA: 85-90 H -RVA: 40 V -RVA- 35 Br Heart J: first published as 10.1136/hrt.43.4.481 on 1 April 1980. Downloaded from

Phase 3 block in normal and accessory pathways 485

LEFT BUNDLE-BRANCH BLOCK IN PATIENTS where the authors postulated that this conduction WITH WOLFF-PARKINSON-WHITE disturbance might have been present in a patient SYNDROME TYPE A with WPW syndrome. According to Krikler et al.13 In contrast, as recently emphasised by Krikler the left bundle-branch block occurring in one of the et al."3 fewer reports have dealt with left bundle- cases (with WPW type A) reported by Pick and branch block coexisting with WPW type A.10"2 Fisch" was probably tachycardia-dependent. In Moreover, Krikler et al.13 also reviewed the pub- our patient this diagnosis was possible because, lished reports and presented information from two regardless of the underlying electrophysiological personal cases in which electrophysiological studies mechanism, pre-excitation did not occur during were performed. (Fig. 1A). Furthermore, left bundle-branch block was not seen when pre- RATE-UNRELATED LEFT BUNDLE-BRANCH excitation was abolished with intravenous pro- BLOCK IN PATIENTS WITH cainamide while the rate was slower (Fig. 1D). WOLFF-PARKINSON-WHITE SYNDROME After development of persistent right bundle- TYPE B branch block, the tachycardia-dependent (phase 3) In the very few reports dealing with this combina- left bundle-branch block naturally coexisted with tion, the diagnosis was made by electrocardio- the former, thus being manifested as infra-Hisian graphic and (or) vectorcardiographic analysis. (bilateral bundle-branch) block in alternate beats However, as stated by Krikler et al.13 'final proof (Fig. 2 and 3). requires electrophysiological techniques'. There- fore, it is possible to question some tracings (show- VARYING QRS MORPHOLOGIES ing short PR intervals and very wide QRS com- The patient discussed in this communication is plexes) which were attributed to WPW type B unique, in that she had, at one time or another, coexisting with left bundle-branch block either ventricular complexes representing: (a) exclusive because 'after the endpoint of pre-excitation there normal (AV node-His Purkinje) pathway conduc- was further prolongation of the QRS'," or because tion without bundle-branch block (Fig. 1D); (b) 'horizontal QRS loops with leftward and posteriorly predomonant or exclusive AV conduction through oriented delta and maximal vectors were followed a right-sided accessory pathway (Fig. 3, right by additional mid-delays and slurrings'.2 panel); (c) pure right bundle-branch block (Fig. 2 In the light of recently acquired information they and 3); (d) pure left bundle-branch block (Fig. 1A); http://heart.bmj.com/ can be explained by assuming exclusive AV conduc- (e) fusion complexes resulting from the coexistence tion through a right-sided accessory pathway, of (a) and (b) (Fig. 1B and C); and (f) fusion without necessarily postulating the concomitant complexes resulting from the coexistence of (b) existence of left bundle-branch block.'6 This access- and (c) (Fig. 2 and 3). However, fusion caused by ory pathway could be atrioventricular ('Kent') as well simultaneously occurring WPW type B and left as fasciculoventricular ('Mahaim'). Electrophysio- bundle-branch block could not be identified, and logical verification is essential, because similar this association still requires further electro- patterns can occur when the ventricles are activated physiological evaluation. on September 26, 2021 by guest. Protected copyright. almost simultaneously by impulses emerging from a right anterior (parietal or septal) accessory pathway and from the right bundle-branch (in cases where References This the left bundle-branch is completely blocked). 'Pick A, Fisch C. Ventricular pre-excitation (WPW) was shown in the studies of Latour and Puech24 and in the presence of . Am Heart J Mendoza et al.2" where simulated (catheter- 1958; 55: 504-12. induced) right septal pre-excitation was produced 2Castellanos A Jr, Mayer JW, Lemberg L. The in patients with left bundle-branch block. The electrocardiogram and vectorcardiogrrm in Wolff- ventricular complexes resulting from iatrogenic Parkinson-White syndrome associated with bundle right ventricular pre-excitation were as wide as branch block. Am J Cardiol 1962; 10: 657-66. (but of different morphology from) those occurring 3Robertson PGC, Emslie-Smith D, Lowe KG, Watson when sinus rhythm (with left-bundle-branch block) H. The association to type B ventricular pre- excitation and right bundle branch block. Br Heart J was present. 1963; 25: 755-62. 4Schamroth L, Krikler DM. Location of the pre- TACHYCARDIA-DEPENDENT (PHASE 3) excitation areas in the Wolff-Parkinson-White syn- LEFT BUNDLE-BRANCH BLOCK IN PATIENTS drome. Am J Cardiol 1967; 19: 889-91. WITH WOLFF-PARKINSON-WHITE SYNDROME 'Durrer D, Schuilenburg RM, Wellens HJJ. Pre- As far as we know there is only one reported case excitation revisited. Am J Cardiol 1970; 25: 690-7. Br Heart J: first published as 10.1136/hrt.43.4.481 on 1 April 1980. Downloaded from

486 Mendoza, Castellanos, Sung

6Castellanos A Jr, Castillo CA. His bundle recordings bundle recordings and cardiac pacing in evaluation of in right bundle branch block coexisting with iatrogenic the pre-excitation (Wolff-Parkinson-White) syndrome. right ventricular pre-excitation. Br Heart J7 1972; 34: Am J Cardiol 1972; 30: 623-8. 153-9. "Durrer D, van Dam RTh, Freud GE, Janse MJ, 7Coumel Ph, Attuel P. Reciprocating tachycardia in Meijler FL, Arzbaecher RC. Total excitation of the overt and latent pre-excitation. Influence of functional isolated human heart. Circulation 1970; 41: 899-912. bundle branch block on the rate of the tachycardia. 18Linenthal AJ, Zoll PM. Ventricular fusion beats EurJ_ Cardiol 1974; 1: 423-36. during electric stimulation in man. Application to 8Lombardi M, Masini G. Lapre-eccitazione ventricolare: conduction velocity and anomalous A-V excitation. contributo clinico-sperimentale. Milan: Ricordati, 1966: Circulation 1965; 31: 651-60. 83. '9Lewis T. The mechanisms and graphic registration of 9Scherf D, Bornemann C. Two cases of pre-excitation the heart beats. London: Shaw & Sons, 1925: 93, 94. syndrome. J Electrocardiol 1969; 2: 177-84. 20Przybylski J, Chiale PA, Quinteiro RA, Elizari MV, °0Denes P, Goldfinger P, Rosen KM. Left bundle branch Rosenbaum MB. The occurrence of phase-4 block in block and intermittent type A pre-excitation. Chest the anomalous bundle of patients with Wolff- 1975; 68: 356-8. Parkinson-White syndrome. Eur Jf Cardiol 1975; 3: 1Touboul P, Huerta F, Arnaud P, Porte J, Delahaye JP. 267-80. etude electrophysiologique de deux cas de pre- 2ICastellanos A, Aranda JM, Gutierrez R, Befeler B. excitation ventriculaire compatibles avec la presence Effects of pacing site on QRS morphology in Wolff- de fibres de Mahaim. Arch Mal Coeur 1975; 68: 841- Parkinson-White syndrome. With special reference to 51. 'pseudo-tachycardia-dependent block in accessory "Baudouy M, Molina B, Varenne A, Guiran JB. pathway' and 'atrial gap'. Br Heart J 1976; 38: 363-8. Syndrome de Wolff-Parkinson-White du type 'A' 22Garcia OL, Castellanos A, Sung RJ, Gelband H. associe a un bloc de la branche gauche. ttude electro- Exposure of concealed right bundle branch block in cardiographique, vectorcardiographique et electro- Wolff-Parkinson-White syndrome type B by pacing physiologique endocavitaire. Arch Mal Coeur 1976; from the vicinity of the A-V node. Am Heart J 1978; 69: 523-32. 96: 662-8. 1Krikler D, Coumel Ph, Curry P, Oakley C. Wolff- 23Follath F, Hallidie-Smith KA. Unusual electrocardio- Parkinson-White syndrome type A obscured by left graphic changes in Ebstein's anomaly. Br Heart Jf bundle branch block. Eur J Cardiol 1977; 5: 49-62. 1972; 34: 513-9. "Castillo CA, Castellanos A Jr, Befeler B, Myerburg RJ, 24Latour H, Puech P. Electrocardiographic endocavitaire. et Cie, 282. Agha AS, Vagueiro MC. Arrival of excitation at right Paris: Masson 1957; 123, http://heart.bmj.com/ ventricular apical in Wolff-Parkinson- 25Mendoza IJ, Sung RJ, Mallon SM, Castellanos A, White syndrome type A, with and without right bundle- Myerburg RJ. Multiple intracardiac recordings in branch block. Br Heart J 1973; 35: 594-600. evaluation of patterns occurring during attempted His 15Befeler B, Castellanos A Jr, Castillo CA, Agha AS, bundle pacing in man. AmJ Cardiol 1978; 41: 1068-74. Vagueiro MC, Myerburg RJ. Arrival of excitation at the right ventricular apical endocardium in Wolff- Parkinson-White syndrome type B. Circulation 1973; Requests for reprints to Dr Agustin Castellanos, 48: 655-60. Division of Cardiology (D-39), University of Miami School of Medicine, PO Box 016960, Miami, GCastellanos A Jr, Agha AS, Portillo B, Myerburg RJ. on September 26, 2021 by guest. Protected copyright. Usefulness of vectorcardiography combined with His Florida 33101, USA.