血圧降下時の直接誘導心電図の実験的研究

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It is a well known fact that the ST-depression in electrocardiogram occurs in coronary insufficiency and other heart diseases. Many authorities have regarded the ST depression as a reciprocal effect of the ST elevation which must be occuring in damaged endocardium.Using direct lead from the surface of the epicardium and reducing the blood pressure artificially by controlled bleeding, Prinzmetal and Toyoshima et al produced a primary S-T depression which was not due to any other myocardial lesion. Furthermore, they reported that this S-T depression occured sporadically in the heart muscles and projected to the chest leads as an S-T depression.To ascertain whether the S-T depression in the chest leads after the blood pressure has been reduced is due to the effects of the S-T depression area that is found sporadically in subepicardium, or due to the S-T elevated-area found in the subendocardium (which has hitherto been said), the author attempted to reduced the blood pressure and, after the blood pressure had been reduced, investigate the electrocardiogram through the use of the combination of a direct unipolar lead, a chest lead and an intramural lead.Method : The author employed dogs which were anesthetized with "Oltopan Sodium", the dogs then were given artificial respiration and their chest was opened to explose the heart. The blood pressure was taken before and after the controled bleeding and the electrocardiograms were recorded by the use of special direct electrodes.Result : A series of the experiments were performed for the following three purpose; namely, A) the comparison of electrocardiographic changes between the precordial and the direct leads on an epicardial or endocardial surface, B) the comparison between the epicardial and the endocardial eads, C) the observation of electrocardiographic changes in the intramural leads.A) Comparison between the precordial lead and the direct lead : It was observed that the R-ST deviation caused by a fall in the blood pressure scarcely occured uniformly, but in most cases insularly. A similar R-ST deviation was found in the chest lead where the potential changes in the epicardial area would be reflected most noticeably. The ST deviation in the epicardial lead, however, was not always accompanied by an ST deviation in any standard chest lead. That is, there was a dead zone in the six standard chest leads.B) Comparison between the epi- and endocardial leads.The ST deviation was observed more frequently in the epicardial lead than in the endocardial lead. It was shown that the ST depression became more noticeable at a certain level of the blood pressure. There is no rule for the successive changes of the T waves and there is no time relationship between an ST deviation and changes of the T waves in any of the direct leads. A transient ST elevation was observed in the majority of cases prior to the depression. An ST deviation was influenced from time to time by the amount or the speed of bleeding.C) Comparison among the intramural leads.With a gradual decrease in the blood pressure the ST deviation could be increasingly seen in the intramural lead. This effect also could be seen more noticeably in the outer layer of the muscle.The author performed another series of experiments in order to ascertain whether or not these ST deviations were caused by a fall in the blood pressure. It was shown that these deviations could be restored either by the administration of pressor drugs or by blood transfusion. After the blood pressure was drastically decreased to 20 mmHg or less, the ST deviation could not be restored by an increase of the pressure, and the dogs died. An amplitude and/or a pattern of the QRS complex was influenced by a fall in the blood pressure. As a rule, the amplitude increases at first and then decreases after a further fall in the blood pressure. Successive changes of amplitude in the chest lead did not always keep pace with those of the epicardial lead.There is no rule for
社団法人日本循環器学会の論文
1960-02-20

血圧降下時の直接誘導心電図の実験的研究

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