The Experimental Studies on the Stimulus Conduction of the Interatrial Septum and it's Circumferences, Particulary the Sino-Tawara System (II) : CUTTING EXAMINATION AT THE INTERATRIAL SEPTUM AND IT'S CIRCUMFERENCE

As reported in part I, it could not be determined that the excitation was spread by which of the proper muscle or the specific muscle at the interatrial septum. Then, in this report, the specific conduction muscles which were related by Osawa as the systema sino-Tawara were cut by a small messer and the PQ intervals were mesured before and after cut.The summary and conclusion of this study are as follows : 1) The cut of the area of the systema septoangularis posterior were performed in 15 cases. In 13 cases, the PQ interval was prolonged or shortend less than 0.010 of a second after cut, that is, the change of the PQ interval was only a little.2) The cut of the area of the systema septoangularis anterior was performed in 23 cases. Then in 17 cases, which cut this system, the PQ interval was prolonged 0.011 to 0.042 of a second (histological examination in 9 cases) and in the cases which it could not be cut, the PQ interval practically did not change.3) In 17 cases, the cut was performed under the sinus coronarius which included the right auricular bundle and the left auricular bundle and the atrio-ventricular node. Then, in 8 cases which the right auricular bundle was cut (histological examination in 5 cases), the PQ interval was prolonged 0.020 to 0.157 of a second. In one case which the both auricular bundle were cut, the PQ interval was prolonged 0.033 of a second. In 4 cases which the atrio-ventricular node was injured, 2 cases A-V block, other 2 cases prolongation of the PQ interval 0.136 to 0.198 of a second (histological examination). In one case which the right and left auricular bundle and atrio-ventricular node were not injured by histological examination, it was recognized the prolongation of the PQ interval was slightly 0.007 to 0.016 of a second.4) In 2 cases in which the cut of the Torus Loweri was performed, the prolongation or shortening of the PQ interval was only 0.002 of a second.5) By contrast, when the right atrial free wall was cut, the PQ interval was prolonged or shortend only 0.008 of a second.6) In 7 cases, the PQ interval was prolonged 0.080 to 0.058 of a second by Bachmann's bundle (histological examination in 4 cases), and in cases which the prolongation of PQ interval was evident, the systema septo-angularis anterior was ligated with it or previously other systems had been ligated.From the above data, it was thought that the 4 specific atrial muscles which were noticed by Osawa, plaied an important role as the stimulus conduct