Plethysmography is a volumetry method for the study of the peripheral blood circulation, which can be used to measure the blood flow by combination of the venous occlusion method. For this purpose the classic mechanical plethysmography and recently advanced mercury-in-gauge plethysmograph are the most available, but the former is not conveniently to be handled and both can only be used on finger or hand.
The photoelectric or impedance plethysmograph is easy to handle and can be used on any portion of the skin, but has a deficit of being incapable of recording the absolute volume changes. They are adapted, however, to observe the comparative vascular responses characteristic to various physiological and pathological conditions.

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In contrast to the scalar electrocardiogram, which merely shows changes of the potential difference of the lead, the aim of the spatial vectorcardiogram is to show the cardiac electromotive force directly. Whether this can be recorded faithfully or not, overcoming difficult problems between the cardiac electric generator and the human body conductor, depends on the development of the basic theories of the electrocardiogram, on the basis of which the lead systems of the vectorcardiogram have been devised. A discussion is described on the discrepancies resulting from the old simple theories and on the extent to which they are resolved by recent theories originated by Burger and Van Milaan and developed by, Frank, Schmitt, McFee and Johnston, and others.
Whether we should choose the old simple but practical theory or the new complicated theory of the electrocardiogram depends upon the degree of accuracy required for each purpose. It is not that the old concept was wrong and the new one is correct. In every-day reading of electrocardiograms the first approximation, such as Einthoven's model, and the old concept, is probably still more-or-less sufficient. But it has been shown that the old concept is probably not sufficient as the basic theory of vectorcardiography. One of the reasons is that vectorcardiograms from the same person obtained by different old systems often differ remarkably from each other, whereas those obtained by new systems resemble each other much more. This does not mean that the latter are perfect, because with closer comparison, we can find many minute points of difference even among them. It is hoped to devise a more accurate and practical lead system, if possible. To discover new practical values of the vectorcardiogram proper it is suggested that more attention be paid to the shape of the vector loop, (circular, ellipsoild, linear etc), which is caused by the minute phase difference of the two perpendicular leads introduced into the cathode-ray-oscilloscope.
The vectorcardiogram has, for a long time struggled to establish its own raison d'être in rivalry with the electrocardiogram, but now the fight seems about to end, since both will be united in a form for automatic diagnosis of electrical phenomena of the heart. The only choice is which is better to introduce into the computer. Or a quite new form may have to be devised for this purpose.

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For the purpose of automatic measurement of eletrocardiogram by an electronic computer of medium sized capacity, the following device has been made. The electrocadiogram recorded on magnetic tape is digitalized by an A-D converter at a sampling rate of 400/sec Smoothing is performed by use of moving average of successive 8 points or multiples of 8 points, because AC is 50 cps in the Tokyo area. Because moving variance is definitively larger at QRS deflection than at other periods in any case, the point showing maximum variance is found at the first step and is used as the key point for wave recognition. Separating points of waves (beginnings and ends of P, QRS and TU) are determined by diminution of gradient below the given critical value or augumentation of difference in gradients (in other words, the second derivative) above the given critical value, tracing the curve in antegrade or retrograde direction from the key point. Not only the tops and bottoms of waves but also all the points where the curve changes markedly in its direction are found by similar methods. The line connecting the beginning of Q wave with that of the following cylcle is regarded as zero level. Smoothing is performed simultaneously, not in advance, with these procedures. Because various processes to check mistakes in determination are added, the program seems slightly complicated, but the amount of computation is rather smoll, resulting in a shortening of the computation time.

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As a first step in research project for the development of a labor monitoring system, we have constructed a digital fetal heart monitor, which is able to demonstrate the instantaneous fetal heart rate per minute as a digital number at every fetal QRS pulse on the three nixie tubes and to take the analog record on an ink-writing oscillograph. The system we have developed can also analyse the fetal ECG wave forms on a storage oscilloscope and can monitor the heart rate by light and sound signals.
As for the clinical applications of this monitor, characteristic patterns of the IHR variations of the fetuses who were complicated with circulation disturbance of the cord, fetal distress syndrome and marked tachycardia up-to 200 beats per minute are presented.
Grounded upon the latest finding of the possibility of maternal ECG elimination in FECG by a unipolar leed system on the abdomen, and upon the identification of probable signs of oneset of crying of an asphixiated fetus in utero by the analysis of FECG informations further development of research and its clinical applications are anticipated.

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An induction type cardiac pacemaker which does not use high frequency carrier waves has been developed. In this pacemaker, transmitting and receiving coils with cores of strips of iron are used, so that it gives high power transmission efficiency with simple circuits. Design principles, electric characteristics and clinical results of the pacemaker are presented in this paper.

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The study of slow potential changes and steady potentials of the brain is lagging behind the great development of the study of fast electrical potential changes (EEG, action potential etc.) in the study of the electrical activity of the human brain. But from the clinical viewpoint it is important to know the meaning not only of electroencephalogram but also of these electrical potential changes. Investigators have reached different conclusions about slow potential changes and steady potentials because of noise and other difficulties at measuring. ²⁾ The authors, therefore, defined the electrical phenomena. They are as follows : (1) Steady potential (SP) changes with organic factor of the brain. (2) Slow potential changes (sp) change with functional factor of it. (3) Fluctuating potentional (EEG).
In this paper, in reference to SP, the authors' apparatus and method of measuring, and some unstable results brought on by noise, are discussed and explained.
The authors' conclusion is as follows : since definite changes are recorded in clinical cases of organic cerebral lesions by using this method of measuring SP, its clinical application is useful to diagnostic investigation. ^{3) -6)} the authors hope the study of SP and sp is of use to the progress of electro-physiological investigation of the brain.

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An examination of the relations between the Doppler signals obtained by the Doppler method and the echo curve obtained by pulse method must be made regarding the same object at the same cardiac cycle. For this reason an apparatus with which the both methods can be applied simultaneously for the same object was produced.
The probe consists of an inner disc-like transducer and an outer surrounding one arranged concentrically. The inner one is for the Doppler method (3Mc), and the outer one for the pulse method (2Mc). The sizes of both transducers are determined to have nearly equal directivity. Since the pulse noise comes into the Doppler set through mechanical and electrical coupling between both transducers, the probe must be so constructed as to be free from couplings between them. The Q's of the Doppler amplifier must be high, in order to reject the pulse noise. The Q's value of this set is more than 100.
The pulse set is the same as an ordinary ultrasonic flaw detector, but echo pulses are displayed on CRT as brightness variation instead of amplitude variation. The peak power and pulse width of ultrasonic pulse were about 0.1 Watt/cm2 and 5 its respectively and the gain of the pulse set was about 90 db.
The Doppler signals and echo curves are recorded, simultaneously but separately on a magnetic tape and on oscillopaper respectively, on both of which tonal burst of 4000 c/s triggered by QRS are superimposed for some time while recording. This enables one to compare and examine both records for the same cardiac cycle.
As a result a good correspondence was found between the Doppler signal and the echo curve of the mitral valve obtained simultaneously ; and so with the tricuspid valve.
When both methods are applied simultaneously, they help one another and the reliability of observation results can be increased.

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Many observers have noticed that when blood flows in a blood vessel of a living animal or in a narrow rigid tube, the red cells appear to drift to the axis, and it has been suggested that this phenomenon is important in accounting f or the anomalous flow properties of blood.
It is shown in this paper, through an analysis, based on fluid mechanics, about a simplified mathematical model of blood flow, that the axial movement of a blood cell, which is independent of the initial velocity of the cell, results from the effect of the inertia of the homogeneous liquid surrounding the cell.

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[in Japanese]

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