Atypical Wenckebach periodicity simulating Mobitz II AV block.

El‐Sherif, Nabil; Aranda, Juan M.; Befeler, Benjamin; Lazzara, Ralph

doi:10.1136/hrt.40.12.1376

Cited by 41 publications

(19 citation statements)

References 21 publications

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“…By comparing the PR interval of the first beat in the long Wenckebach cycle with that of those beats immediately preceding the blocked P wave, the increment in AV conduction becomes readily apparent. 62 8) Finally, the classic AV Wenckebach structure depends on a stable atrial rate and a maximum increment in AV conduction time for the second PR interval of the Wenckebach cycle, with progressive decrease in subsequent beats. Unstable or unusual alterations in the increment or atrial rate, often seen with long Wenckebach cycles, result in atypical forms of type I AV block and are quite common.32 63 PR Shortening after the Blocked P Wave…”

Section: Electrophysiological Characteristics Of the Av Nodementioning

confidence: 99%

Second-degree atrioventricular block.

Zipes¹

1979

Circulation

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by analyzing the A, C and V waves in the jugular venous pulse, described two types of second-degree atrioventricular (AV) block. After the introduction of the electrocardiograph, Mobitz4 classified the two types of block as type I and type II. Electrocardiographically, typical type I second-degree AV block is characterized by progressive PR prolongation culminating in a nonconducted P wave, while in type II second-degree AV block, the PR interval remains constant before the blocked P wave. In both instances, the AV block is intermittent, generally repetitive and may involve several P waves in a row. Usually, the eponym Mobitz type I and Mobitz type II AV block is applied to the two types of block, while the term "Wenckebach block" refers to type I AV block only.The purpose of this paper is to provide both a brief review of clinically relevant electrophysiologic and electrocardiographic concepts of AV conduction and block, and a critical evaluation of the present classification of second-degree AV block.Electrophysiological Characteristics of the AV Node and His-Purkinje System Since the difference between type I and type II AV block, in most instances, probably relates to the site at which the block occurs, it is important to review the electrophysiological properties of the tissues involved.Transmembrane action potentials recorded from cells within the AV node differ markedly from those recorded in the His-Purkinje system. AV nodal cells display reduced action potential amplitude, duration, resting potential, conduction velocity, maximum rate

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Section: Electrophysiological Characteristics Of the Av Nodementioning

confidence: 99%

Second-degree atrioventricular block.

Zipes¹

1979

Circulation

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“…It was not necessarily the longest PR interval that was followed by the blocked impulse. Denes 1 2 called such episodes "atypical Wenckebach periods", although some authors refer to them as Mobitz type II, 1 3 "Mobitz type IIlike", 14,15 "pseudo mobitz type II" 16,17 or "apparent Mobitz type II". 1 4 However, the site of block is probably a more important determinant of prognosis and the need for pacemaker therapy than the type of block.…”

Section: Discussionmentioning

confidence: 99%

Arrhythmias during spinal anesthesia for Cesarean section

Shen¹,

Ho²,

Hung³

et al. 2000

Can J Anesth/J Can Anesth

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Purpose: Spinal block has long been considered a safe anesthesia technique for surgery. However, severe bradycardia, cardiac arrest, and other arrhythmias during spinal anesthesia have been reported and the incidence of intraoperative arrhythmias is not well established. In this study the incidence of arrhythmias during spinal anesthesia was determined. Methods:We studied 254 healthy women undergoing Cesarean section under spinal anesthesia prospectively. Spinal anesthesia with 10 mg bupivacaine mixed with 0.2 mg morphine was performed at the L 3-4 interspace. Intraoperative arrhythmias were recorded and verified later by a cardiologist.Results: First degree atrioventricular block developed in nine patients (3.5%), second degree atrioventricular block in nine (3.5%), severe bradycardia (heart rate < 50 beats·min -1 ) in seventeen (6.7%), multiple VPC in three (1.2%). The height and weight of patients with severe bradycardia, multiple VPCs, or atrioventricular block were not different from those of the other patients. However, the age of patients in the potentially dangerous arrhythmias group was greater than that in the other group (P = 0.006). Conclusion:The incidence of arrhythmias as well as hypotension during spinal anesthesia for Cesarean section was higher than expected. Although most of these arrhythmias were transient and recovered spontaneously, they might unexpectedly occur and sometimes need immediate and prompt treatment. It is necessary to remain vigilant during spinal anesthesia for Cesarean section and careful monitoring of these patients is warranted, especially in older parturients.Objectif : On a longtemps considéré la rachianesthésie comme une technique sécuritaire pour la chirurgie. Cependant, des cas de bradycardie sévère, d'arrêt cardiaque et d'autres arythmies ont été signalés pendant la rachianesthésie et l'incidence d'arythmie peropératoire n'est pas bien définie. Dans la présente étude, on a déter-miné l'incidence d'arythmie pendant la rachianesthésie.Méthode : Nous avons fait l'étude prospective de 254 femmes en santé qui ont subi une césarienne sous rachianesthésie. L'injection de 10 mg de bupivacaïne avec 0,2 mg de morphine a été réalisée dans l'espace L 3-4 . L'arythmie peropératoire a été notée et vérifiée ensuite par un cardiologue.Résultats : Un bloc auriculoventriculaire de premier degré s'est développé chez neuf patientes (3,5 %), un bloc de second degré chez neuf patientes également (3,5 %), une bradycardie sévère (fréquence cardiaque < 50 battements·min -1 ) chez dix-sept (6,7 %), de multiples ESV chez trois (1,2 %). La grandeur et le poids des patientes qui ont présenté une bradycardie sévère, de multiples ESV ou un bloc auriculoventriculaire ne différaient pas de ceux des autres patientes. Toutefois, les patientes du groupe présentant des arythmies potentiellement dangereuses étaient plus âgées que les autres (P = 0,006).Conclusion : L'incidence d'arythmie autant que d'hypotension pendant la rachianesthésie pour une césarienne a été plus élevée que prévu. Même si la plupart...

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“…Another important limitation is that in some of our cases the sudden lengthening of the P wave-QRS interval during premature atrial stimulation might have been due to a first-degree intra-Hisian or infra-Hisian block rather than to a jump in AV nodal conduction. However, the occurrence of a first-degree intra-Hisian or infra-Hisian block during premature atrial stimulation is uncommon [22][23][24] , since the refractory period of the AV node is usually longer than that of the His-Purkinije system. Furthermore, in our study, all subjects with a jump in AV nodal conduction also had a discontinuous AV node function curve, supporting the diagnosis of dual AV nodal pathways.…”

Section: Study Limitationsmentioning

confidence: 99%