Tadashi Koide

Reappraisal of the coupling interval of ventricular extrasystoles as an index of ectopic mechanisms

Objective—A mathematical model of modulated ventricular parasystole based on the relation between the coupling interval and the preceding RR interval was developed in an attempt to distinguish between parasystolic automaticity and other mechanisms. Mathematical model—The relation between the coupling interval and the preceding RR interval was examined by plotting the coupling interval of each extrasystole against the preceding RR interval (coupling interval/RR diagram). The coupling interval/RR diagrams obtained from simulations with various modulation modes suggested that the parasystolic mechanism was likely when the dots representing extrasystoles appeared as discrete clusters. In contrast, a linear horizontal accumulation of dots indicated a non-parasystolic mechanism. Clinical observation—To verify the validity of the simulations, 24 hour electrocardiographic recordings from 60 patients with frequent ventricular extrasystoles (>1000/day) were analysed to determine whether the extrasystoles showed intrinsic periodicity. Intrinsic periodicity indicative of a parasystolic mechanism was seen in 14 (93%) of 15 patients in whom the coupling interval/RR diagram was characteristic of a parasystolic mechanism. When the coupling interval did not change (variability <200 ms) over a wide range of RR intervals (>700 ms) intrinsic periodicity was never identified (0/17). Parasystolic automaticity was the likely mechanism in 11 of the remaining 28 patients (39·3%) in whom coupling interval/RR diagrams were not definitive. Conclusion—These data indicate that definite patterns of coupling interval/RR diagrams can be used to distinguish between parasystolic and non-parasystolic mechanisms.

Decrease of Atrial Natriuretic Peptide Content in Rat Superior Cervical Sympathetic Ganglion After Denervation and Axotomy

Abstract: We found atrial natriuretic peptide (ANP), known as a humoral factor in regulating body fluid volume and blood pressure, in considerable quantities in rat superior cervical sympathetic ganglion (SCG) by radioimmunoassay after separation with reverse‐phase HPLC. Although the ANP content of the immature rat 1 week after birth was low, it doubled at 2 weeks and then increased gradually, until it reached the adult level. Denervation caused a rapid decrease in the ANP content to half of the intact SCG level after 3 h, which then fell to 10% of the control value on day 2 after operation. The time course of ANP content reduction after denervation was similar but rather faster than that of activity of the acetyl‐choline‐synthesizing enzyme, choline acetyltransferase, an observation suggesting that ANP may partly contribute to cholinergic synaptic transmission. On the other hand, axotomy produced a rather slower decrease in the ANP content than did denervation. Enucleation and sialoadenectomy also caused a considerable reduction of the ANP content. Thus, part of the ANP found in the ganglion is apparently transported from sympathetically innervated extraganglionic organs via retrograde axoplasmic flow.