Existence of automaticity in anomalous bundle of Wolff-Parkinson-White syndrome.

Przybylski, J; Chiale, Pablo A.; Halpern, M. Susana; Lázzari, Julio O.; Elizari, Marcelo V.; Rosenbaum, Mauricio B.

doi:10.1136/hrt.40.6.672

Cited by 20 publications

(8 citation statements)

References 25 publications

(3 reference statements)

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“…16 To our knowledge our case 2 is the first patient reported where a bradycardia-related retrograde block was proved in a concealed atrioventricular bypass tract. If the range of bradycardia-dependent retrograde block is "far to the right", that is retrograde block in the bypass tract occurs only late in diastole, right ventricular stimulation studies may not be very helpful in disclosing this peculiar disturbance.…”

Section: Discussionmentioning

confidence: 74%

Limitation of tachycardia zone resulting from longitudinal dissociation of the atrioventricular node in concealed pre-excitation.

Littmann¹,

Svenson²

1981

Heart

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SUMMARY Two cases with a concealed left-sided accessory atrioventricular bypass tract are described. In both, functional longitudinal dissociation of the atrioventricular node narrowed the range of atrial premature beat coupling intervals which could initiate re-entry using the accessory pathway. In case 1 early premature atrial beats were followed by an atrioventricular nodal re-entrant echo. The atrial echo pre-empted retrograde conduction over the Kent bundle and thus limited the development of paroxysmal supraventricular tachycardia. In case 2 atrioventricular nodal conduction showed typical features ascribed to dual atrioventricular nodal pathways. In addition there was a bradycardia-related retrograde block in the concealed accessory pathway. Early premature atrial beats, because of exclusive "slow pathway" anterograde conduction, arrived at the ventricles during the period of bradycardia-dependent retrograde block and failed to initiate a macro re-entrant tachycardia. This study shows that (1) longitudinal dissociation within the atrioventricular node may limit the ability to initiate tachycardia in patients with concealed pre-excitation; and (2) discontinuous atrioventricular nodal conduction curves occasionally help to reveal bradycardia-related retrograde block in a concealed accessory pathway.Discontinuous atrioventricular nodal conduction curves and atrioventricular nodal re-entry are common electrophysiological responses to premature atrial stimulation in man.' The former are believed to reflect dual atrioventricular nodal pathways and the latter dual pathways, functional longitudinal dissociation, or reflection within the atrioventricular node.' 2 These phenomena have recently been described in a few patients who also had manifest35 or concealed pre-excitation.69 In most of these reported cases the atrioventricular nodal conduction characteristics were unrelated to the initiation or maintenance of the paroxysmal supraventricular tachycardia.68 In some, the critical atrioventricular conduction delay required for macro re-entry was achieved by block in the fast atrioventricular nodal pathway, and thus initiation of the tachycardia was enhanced by "duality" of atrioventricular conduction.5 9 In a few patients with an accessory pathway, atrioventricular nodal re-entry itself proved to be the mechanism of the tachycardia.4 8 10The purpose of the following report is (1) to present * Dr Littmann is a research fellow of the Heineman Medical Research Center. Parent Institution: Semmelweis University Medical School, Budapest, Hungary. Received for publication 10 December 1980 302 two unusual cases of concealed pre-excitation where atrioventricular nodal re-entry and dual atrioventricular nodal conduction limited rather than enhanced initiation of paroxysmal supraventricular tachycardia with early atrial extrasystoles, and (2) to show for the first time, a bradycardia-related retrograde block in a concealed accessory pathway. Case reportsCase 1, a 57-year-old man, and case 2, a 54-year-old woman, were stud...

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Section: Discussionmentioning

confidence: 74%

Limitation of tachycardia zone resulting from longitudinal dissociation of the atrioventricular node in concealed pre-excitation.

Littmann¹,

Svenson²

1981

Heart

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“…5). Ajmaline is a drug'8 that depresses conduction in the AP,3, 19 21 especially when conduction is naturally depressed.22 25 In one of the four cases (patient 21), retrograde conduction over the AP could not be documented. This was probably an example of naturally occurring total bidirectional block in the AP.…”

Section: Retrograde Conductionmentioning

confidence: 99%

Unmasking of ventricular preexcitation by vagal stimulation or isoproterenol administration.

Przybylski¹,

Chiale²,

Halpern³

et al. 1980

Circulation

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Twenty-one patients were studied in whom ventricular preexcitation (VP) had been recorded in the past and had later disappeared, indicating antegrade block in the accessory pathway (AP), either spontaneously (10 patients) or under the effect of chronic treatment with amiodarone (11 patients). VP reappeared in nine cases during vagal stimulation, and in five cases during an i.v. isoproterenol infusion. Retrograde conduction over the AP was studied in four of the remaining seven patients and was found to be present in three and absent in one. Although these patients differ from the ordinary patient with concealed AP in that antegrade preexcitation had been demonstrated in the past, this study suggests that concealed VP may result from the following mechanisms: 1) an extremely prolonged refractory period in the AP, causing a rate-dependent VP that can be identified during vagal stimulation; 2) a rate-independent depression of antegrade conduction that can be reversed by isoproterenol; 3) a depression of conduction that is apparently no longer reversible. Only in the latter case is a study of retrograde conduction needed to identify the concealed VP. These three mechanisms are likely to be a natural sequence of events leading to complete antegrade block in the AP.

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“…However, it could not be determined whether this tract was an 'abnormal' atrio-His connection or a 'normal' transitional (atrio-atrioventricular nodal) tract. Though intracardiac studies complement body surface recordings, they should be interpreted with knowledge of their inherent limitations.Most studies dealing with automaticity of accessory pathways have referred to ectopic beats arising in Kent tracts as reported in recent reviews on this subject (Przybylski et al, 1975;Castellanos et al, 1976). It seems appropriate, therefore, to discuss two possible examples of impulse formation in atrioventricular nodal bypass tracts.…”

mentioning

confidence: 99%

“…Most studies dealing with automaticity of accessory pathways have referred to ectopic beats arising in Kent tracts as reported in recent reviews on this subject (Przybylski et al, 1975;Castellanos et al, 1976). It seems appropriate, therefore, to discuss two possible examples of impulse formation in atrioventricular nodal bypass tracts.…”

mentioning

confidence: 99%

Evaluation of intracardiac recordings in diagnosis of impulse formation and concealed conduction in atrioventricular nodal bypass tracts.

Castellanos¹,

Agha²,

Mendoza³

et al. 1977

Heart

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Invasive electrophysiological studies were performed in 2 symptomatic patients with recurrent arrhythmias in which impulse formation presumably occured within atrioventricular nodal bypass tracts. Case 1 had ectopic beats arising within, or close to, the upper end of a left-sided atrioventricular nodal bypass tract of the type described by Brechenmacher. In addition, this conduction was 'concealed' during sinus rhythm and right atrial pacing because the relatively prolonged right-to-left atrial conduction time allowed right atrial impulses to reach the His bundle via the atrioventricular node before they could do so through the atrioventricular nodal bypass tract. Case 2 had ectopic beats arising in a right-sided atrioventricular nodal bypass tract which did not conduct in either forward or retrograde directions, its presence being detected only when initiating impulses. However, it could not be determined whether this tract was an 'abnormal' atrio-His connection or a 'normal' transitional (atrio-atrioventricular nodal) tract. Though intracardiac studies complement body surface recordings, they should be interpreted with knowledge of their inherent limitations.

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Existence of automaticity in anomalous bundle of Wolff-Parkinson-White syndrome.

Cited by 20 publications

References 25 publications

Limitation of tachycardia zone resulting from longitudinal dissociation of the atrioventricular node in concealed pre-excitation.

Limitation of tachycardia zone resulting from longitudinal dissociation of the atrioventricular node in concealed pre-excitation.

Unmasking of ventricular preexcitation by vagal stimulation or isoproterenol administration.

Evaluation of intracardiac recordings in diagnosis of impulse formation and concealed conduction in atrioventricular nodal bypass tracts.

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