Experiences with 200 transseptal catheterizations of the left heart are reported. The percutaneous insertion of the catheter into the femoral vein offers essential advantages. Investigations of all cavities of the heart may be performed through a single venous intubation. The examination have been carried out in patients with left-sided heart valve disease, especially aortic valve lesions, in complex congenital malformations and endocardial fibroelastosis. Own complications and incidents, as reported by different authors, are discussed. Severe complications can be avoided by use of the modified technic. The percutaneous transseptal catheterization is superior to other methods of left heart catheterization. The advantages and possibilities of the method are demonstrated.

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(1) In order to find an adequate lead for recording the electrocardiogram during exercise, 6 modifications of Frank's Y-lead were studied.
(2) For this purpose, factors examined were the phase difference, the voltage, the wave form as cardiac factors and the interference by electrical activity of the muscle and the influence of respiration as non cardiac factors.
(3) The study in 34 cases without the marked intraventricular conduction disturbance indicated that the lead, in which a positive electrode at the height of the umbilicus and a negative one is placed in the subclavicular region along the right mid-clavicular line, is recommended.
(4) In practice, electrodes by Frank's lead system and other 2 extraelectrodes by the modified lead are placed. The amplification of the modified lead is adjusted to the amplitude of the original one. With this method, records which is electrically equivalent to those by Frank's lead system can be taken with little interference.

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(1) In open-chest, anesthetized dogs with the coronary perfusion pressure kept constant, the brain stem was electrically stimulated and the changes in coronary flow were observed in the course of pressor responses elicited.
(2) On stimulation of vasopressor areas, coronary flow showed a biphasic change characterized by an initial slight decrease followed by a subsequent marked increase of longer duration.
(3) Changes in heart rate, systole to cycle ratio, and Tension-Time Index were also investigated, and no apparent relationship was shown to exist to coronary flow.
(4) The initial transient decrease is partly due to sympathetic coronary vasoconstriction and partly due to increased extravascular compression upon coronary vessels induced by sudden hemodynamic change. The subsequent increase is secondary effect to nervous stimulation.

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(1) The ventricular gradient (G) vector was determined with Frank's lead system in 60 normal subjects. In some cases, the effect of eyeball or carotid sinus pressure, atropine sulfate, upright position and amyl nitrite was examined.
(2) The average magnitude of the G vector was 80.3μv•sec. and its average direction was 44° and 27° in the frontal and horizontal plane, respectively.
(3) In acute experiments with various agents, the magnitude of the G vector increased or decreased along with the RR interval. The directional change of the G vector relative to the QRS vector was small. The importance of the G vector in analysing the acute electrocardiographic changes, especially in the horizontal plane, was discussed.
(4) The change in the G magnitude relative to the RR or QT change was larger in the experiments with standing position and amyl nitrite than in the other 2 experiments, which might be related to the difference between the heart rate changes of sympathetic and parasympathetic origin.

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(1) U-loop vectorcardiograms were obtained from 53 patients by the method of differential vectorcardiography. The subjects were composed of 11 cases of right ventricular hypertrophy, 21 cases of right bundle branch block and 21 cases of myocardial infarction.
(2) The U loop of right ventricular hypertrophy and of complete or incomplete right bundle branch block resembled that of normal subjects. Namely, it had a shape like a small, slightly curved club and was inscribed in the direction of continuance of the terminal limb of the T loop. A few cases of right bundle branch block showed a definite exception to this statement.
(3) The U loop of myocardial infarction began with a marked bend at the T-U junction and extended in various directions. It resembled also a small curved club, but was sometimes much larger than normal U loops. Namely, it resembled that of left ventricular hypertrophy. But the U loop abnormality in myocardial infarction was usually more marked than in left ventricular hypertrophy.
(4) In reviewing the U loop abnormality in ventricular hypertrophy, bundle branch block and myocardial infarction at least 2 factors could be thought of to cause the U loop abnormality: hypertension and organic changes in the myocardium.

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The electrocardiographic and vectorcardiographic changes produced by electrical stimulation of the cardiac nerves were investigated.
(1) Stimulation of the right stellate ganglion produced superior displacement of the spatial T loop with change in its direction of inscription from clockwise to counterclockwise in the right sagittal plane.
(2) With stimulation of the left stellate ganglion, the T loop increased its magnitude inferiorly with or without preceding transient superior displacement. The superiorly displaced T loop was inscribed clockwise in the right sagittal plane, which was different from the counterclockwise inscription of the T loop observed with stimulation of the right stellate ganglion.
(3) From these results, there appears to exist some difference in the innervation of the myocardium by right and left cardiac sympathetic nerves.
(4) Stimulation of the cervical vagus nerves produced minimal changes in the electrocardiogram and vectorcardiogram, and no definite results were obtained from the examination of the vector loop.

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A case of severe hypertension caused by the left renal vascular stenosis with aplasia of the right kidney was presented. The causative lesion of this renovascular stenosis is considered to be fibrous or fibromuscular hyperplasia of the renal artery.

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A case of ventricular paroxysmal tachycardia with abnormal P waves is presented. As regard to the identification of P waves during paroxysm, the high gain electrocardiogram is more useful than the conventional electrocardiogram. The P wave abnormalities are considered to show left atrial overloading. The conduction disturbance in the atria may be the precipitating factor for the ventricular tachycardia.

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