Influence of Cycle Length Upon Refractory Period of Auricles, Ventricles, and A-V Node in the Dog

Méndez, Carlos; Gruhzit, Carl C.; Moe, Gordon K.

doi:10.1152/ajplegacy.1956.184.2.287

Cited by 147 publications

(46 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…As heart rate is inversely related to age (16,21), and as refractory periods are related to heart rate (5,20), faster heart rates in children could account for the shorter refractory periods. Friedman et al (10) demonstrated shorter refractory periods in isolated lamb ventricular myocardium compared with adult sheep, suggesting that age may be an additional factor.…”

Section: Discussionmentioning

confidence: 99%

The Influence of Age on Cardiac Refractory Periods in Man

DuBrow¹,

Fisher²,

Denes³

et al. 1976

Pediatr Res

View full text Add to dashboard Cite

Section: Discussionmentioning

confidence: 99%

The Influence of Age on Cardiac Refractory Periods in Man

DuBrow¹,

Fisher²,

Denes³

et al. 1976

Pediatr Res

View full text Add to dashboard Cite

“…Rosenblueth, Mendez, and their respective collaborators indicate that the functional refractory period of excitable tissue is the shortest attainable interval between two induced responses when the second stimulus is delivered at 2 or more times the threshold intensity (1,3,9). They emphasized, however, that this value is attended by an error equal to any difference that might occur in the propagation time from the point of stimulation to the point of recording between the first and second responses.…”

Section: Discussionmentioning

confidence: 99%

“…This period, during which a propagated action potential cannot be evoked by a stimulus, has been designated the "effective refractory period" (2), and the effective refractory period thus limits the maximal rate at which depolarizations can occur. When normal atrioventricular (AV) conduction takes place, the ventricular contraction rate is limited by the AV nodal system, which has been shown in experimental animals to have a longer effective refractory period than atrial or ventricular tissue (3). In spite of the fundamental importance of the refractory period of the AV nodal conduction system, this interval has heretofore been estimated only from electrocardiograms obtained from patients with spontaneous cardiac arrhythmias (4).…”

mentioning

confidence: 99%

Determinants of the Duration of the Refractory Period of the Atrioventricular Nodal System in Man*

Linhart¹,

Braunwald²,

Ross³

1965

J. Clin. Invest.

View full text Add to dashboard Cite

“…The functional refractory period of the AV node is the minimum response interval between conducted basic, H,, and conducted premature, H 2 , bundle of His responses propagated from the atrium (13). The functional refractory period of the AV conduction system is the minimum response interval between conducted basic, V,, and conducted premature, V 2 , ventricular responses propagated from the atrium (14 …”

Section: Definitionsmentioning

confidence: 99%

The differences in atrioventricular conduction of premature beats in young and adult goats.

Gough¹,

Moore²

1975

Circulation Research

View full text Add to dashboard Cite

Atrioventricular (AV) conduction was studied in anesthetized, open-chest, 1-35-day-old goats. Atrial, bundle of His, and ventricular bipolar electrograms were recorded, and the functional refractory periods of the AV conduction system and the ventricles were determined. Supraventricular premature excitation invaded the ventricles during their vulnerable period. This AV conduction property is different from that of the adult goat heart; thus, the existence of a lateral accessory bypass tract was investigated. Electrocardiographic leads I, aVF, and V, o revealed no delta waves indicative of ventricular preexcitation. Bundle of His electrograms showed that: (1) bundle of His excitation always preceded the onset of ventricular depolarization, (2) no shortening occurred in the bundle of His to ventricular activation time following early atrial premature beats, and (3) the functional refractory period of the AV node was less than that of the ventricle. The ventricular epicardial excitation sequence indicated no involvement of a lateral bypass tract in the AV conduction of basic or premature beats. Interruption of the bundle of His caused complete AV block. Therefore, no functional lateral accessory bypass tracts are present in the young goat heart, and the AV node and the ventricular specialized conduction system of the young goat are capable of conducting premature atrial excitation to the ventricles within ±10 msec of the expiration of the ventricular functional refractory period.• Atrioventricular (AV) conduction of premature beats has been studied in several different mammalian species (1-6); however, only two reports deal with AV conduction of premature beats in young mammalian hearts (5, 6). Preston et al. (6) have reported that young ventricles are prematurely excited at an interval equal to their functional refractory period by premature atrial beats. This capacity of the AV transmission system for such rapid conduction of premature atrial beats permits premature atrial excitation to evoke ventricular fibrillation. In normal adult dog or human hearts, the AV node serves as a filter to protect the ventricles from early premature atrial beats (4, 6).Two basic mechanisms could explain this AV conduction property of young mammalian hearts: 48(1) the presence of an accessory conducting pathway which bypasses the normal AV node (7, 8) or (2) an AV node which does not have the long refractory, slow conducting characteristics found in most adult mammalian AV nodes. The present study was undertaken to distinguish which mechanism operates in the young goat heart. Four techniques were utilized: (1) electrocardiography, (2) intracardiac recordings from the bundle of His, (3) mapping of the sequence of ventricular epicardial excitation, and (4) surgical interruption of the bundle of His. The results showed that the AV node of the young goat has a shorter functional refractory period than does the adult AV node; we found no electrophysiological evidence to suggest the existence of bypass tracts. MethodsThirty-sev...

show abstract

Influence of Cycle Length Upon Refractory Period of Auricles, Ventricles, and A-V Node in the Dog

Cited by 147 publications

References 0 publications

The Influence of Age on Cardiac Refractory Periods in Man

The Influence of Age on Cardiac Refractory Periods in Man

Determinants of the Duration of the Refractory Period of the Atrioventricular Nodal System in Man*

The differences in atrioventricular conduction of premature beats in young and adult goats.

Contact Info

Product

Resources

About