Isorhythmic dissociation - A "physiological" arrhythmia

Elieser Kaplinsky, Raymond Aronson, Henry N. Neufeld

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The behavior of the sino-atrial mechanismin isorhythmic dissociation (IRD) was studied in 21 patients, nine with spontaneous IRD and 12 with artificially pacemaker-induced IRD following electrode placement for heart block. Successive P-P, R-R and P-R intervals and blood pressure (BP) fluctuations were determined and graphically interrelated at control and during IRD. Several features were observed: a. IRD was present only when the independent ventricular rate was close to the atrial; b. P rate oscillations closely followed the P-R interval-dependent BP fluctuations (mean difference 30 mmHg) during IRD. In cardiogenic shock and in severe hypertension IRD could not be achieved easily; c. While during complete dissociation or during 1:1 A-V conduction the sinus rate was remarkably constant (2-4 beats/min variations), it showed marked oscillations (differences of 6-19, mean 13, beats/min) during IRD. All the data and calculations support the theory that in most instances of IRD, the arrhythmia is sustained by the normal physiologically active baroreceptor reflex arc.

Original languageEnglish
Pages (from-to)179-188
Number of pages10
JournalJournal of Electrocardiology
Issue number2
StatePublished - 1977


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