心房内刺戟伝導に関する実験的研究(第5報) : 洞結節・心房間の刺戟伝導に就て

Abstract

In experiments with seven dog's heart, the author took direct lead ECG simultaneously recorded over the surface of the right and left atrium after locally ligating a place around the sinus node, or the Bachmann's bundle, or the atrial wall etc., and compared one with another of the activation times for both atria before and after the ligation by means of the intrinsic deflection of the P wave, and studied the change in the times of stimulus arrival at both atria. Here a minute histological search on the aspects of the ligated portions was made by Osawa. Following are the results of all these experiments.1) In five cases the Bachmann's bundle was ligated, stimulus arrival at the left atrium immediately after ligation was later by 0.017-0.342 second or 0.092 second on the average than before the ligation took place. But in right atrium no change has occurred. Doubtlessly these facts show that the stimulus conduction from the sinus node to the left atrium was chiefly carried out through the Bachmann's bundle.2) In a case the tail of the sinus node was ligated activation arrival at the right atrium immediately after the ligation was not delayed. However, when the fact is considered that the lead point in a right atrium was the middle part of its anterior wall, we should, concerning the stimulus conduction between the sinus node and the right atrium. suppose the existence of the stimulus conduction pathway that proceed from the head or trunk of the sinus node, other than a pathway that proceeds from the tail of the sinus node.3) In case the Bachmann's bundle, the anterior wall of the right atrium, and the tail of the sinus node were ligated all at the same time P-Q interval in both atrial curve was shortend, that was immediately after the ligation, namely the activation arrival at both atria was delayed. No variation regarding conduction however, was detected in the Tawara's node.This is because, in this instance, the main conduction pathways that stimulus proceed from the simus node to the right atrium and from the sinus node to the left atrium were simultaneously all intercepted, while the pathway from the sinus node to the a-v node was maintained in a perfect condition.4) In an instance, when a greater part around the sinus node excluding the tail was ligated the activation arrival at both atria immediately after ligation was found considerably delayed, in this case supposedly due to the fact that either of the main pathways leading to points on both atria had been intercepted.5) In the experiments above there were three instances in which a complete disturbance of conduction between the left and right atria was unexpectedly observed, the occurrence of which could be easily explained by way of affirming the existence of the specific stimulus conduction pathway between the sinus node and the right atrium, and between the former and the left atrium.In short, stress has been placed on the assertion that there may exist specific conduction pathways rendering direct connection between the sinus node and both the atria through their respective pathways.