Sino-Auricular Block, Interference Dissociation, and Different Recovery Rates of Excitation in the Bundle Branches

Burchell, Howard B.

doi:10.1136/hrt.11.3.230

Cited by 25 publications

(2 citation statements)

References 12 publications

(11 reference statements)

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“…Scherf and Scharf postulated a similar mechanism in a case described by von Hoesslin (1923). Burchell (1949) reported a case of interference-dissociation where the capture beats had either a right or left bundle-branch block pattern. This was dependent upon the R-P interval-the time relation between the R wave of the idionodal pacemaker and the P wave of the atrial pacemaker, and was explained on the basis of different recovery rates of the two bundle-branches.…”

Section: Discussionmentioning

confidence: 99%

The supernormal phase of intraventricular conduction.

Schamroth¹

1969

Heart

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The supernormal phase of conduction is a short period of paradoxically improved conduction which may occur during an early phase of the recovery cycle of cardiac conducting tissue. The situation is paradoxical, for the improved conduction occurs during a short critical early period, while later impulses are blocked or have greater conduction delays. The terminate long cycles-cycles with R-R intervals that range from 106 to 170-have a normal QRS pattern.The fluctuation between normal and abnormal intraventricular conduction indicates that the left bundlebranch block is a manifestation of phasic aberrant ventricular conduction (Schamroth and Chesler, 1963)-the transient, intermittent, or isolated intraventricular conduction of a supraventricular impulse. This phenomenon is basically due to unequal refractory periods of the bundle-branches. When this occurs, a relatively early impulse may encounter a responsive right bundlebranch and a refractory left bundle-branch, and will consequently be conducted with a left bundle-branch block pattern. Longer pauses permit full recovery of both bundle-branches, and late impulses are therefore conducted normally. Prematurity is thus a major factor in the genesis of aberrant ventricular conduction and prematurity must be considered pari passu with the duration of refractoriness. Refractoriness varies directly with the duration of the preceding cycle-the longer the preceding cycle (the preceding R-R interval), the longer the subsequent refractory period, and vice versa (Trendelenburg, 1903;Mines, 1913;Lewis, Drury, and Bulger, 1921). This principle also applies when the refractory periods of the bundle-branches are unequal, i.e. the refractory period of each bundle-branch will also be shortened or lengthened by preceding short or long intervals; and this may effect the conduction of a subsequent early impulse. For example, a premature impulse when preceded by a long cycle may encounter a refractory bundle-branch and be conducted with aberration, whereas an impulse of the same prematurity, when preceded by a short cycle, may find both bundlebranches responsive and will consequently be conducted normally. These principles are obviously of major importance in rhythms such as atrial fibrillation where cycle lengths vary considerably. Any comparison of the conduction sequences of different impulses under such circumstances must therefore take into account the effect of prematurity as well as the effect of the preceding cycle lengths. This comparison is facilitated by plotting each R-R interval against its preceding R-R interval (Fig. 2). The parameters of both prematurity and preceding cycle lengths of different impulses can now be compared. For example, consider a specific point on the graph, reflecting an impulse of certain prematurity that is preceded by a certain cycle length (illustrated as 337 on 27 April 2019 by guest. Protected by copyright.

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Section: Discussionmentioning

confidence: 99%

The supernormal phase of intraventricular conduction.

Schamroth¹

1969

Heart

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“…10 The present study is concerned with reciprocal rhythm in the other direction; an impulse that originates in the SA node or an atrium turns back somewhere in its course to or toward the ventricles to activate the atria again. The study is based on the electrocardiograms of five patients that seem consistent [12][13][14][15][16][17][18][19][20]21 fig. 364, [22][23][24][25][26][27][28][29][30][31][32][33]; in some cases this is not the authors' interpretation.…”

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confidence: 99%