Aconitine was administered to the isolated right atrium of the rabbit, and atrial flutter and fibrillation were induced. The action potentials of unipolar lead electrogram regularly appeared in atrial flutter, and their configuration was different from that in sinus rhythm. In the initial stage of atrial fibrillation, both appearances of the action potentials of unipolar lead and intracellular lead electro-grams were regular and synchronous in some degree. In atrial flutter and fibrillation, the membrane resting and action potentials decreased to various degree. The rising velocity of upstroke of action potential decreased, and the duration of action potential shortened. The steepness of diastolic slow depolarization increased. It may be concluded that atrial flutter results from rapid impulse formation in a single focus. Atrial fibrillation would be caused by rapid impulse formation in multiple ectopic foci.

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Ninety six hospital cases with acute myocardial infarction were analyzed for factors which seemed important to prognosis. Linear discriminant analysis utilizing computer was used for evaluating the severity of illness in acute myocardial infarction. The predictive accuracy of 26 patients received a dead score was 53.8 per cent and that of 70 patients received a living score was 95.7 per cent. Of 12 patients who received a dead score and were treated with anticoagulants, 3 died and of 14 untreated patients, 11 died. Of 66 control patients predicted to live, 64 lived. Among 101 outpatients who were followed up for 5 years, the cardiac death of patients treated with anticoagulants was 3.1 per cent and that of untreated group was 28.0 per cent.

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1) Phonocardiographic studies with other simultaneous hemodynamic observations were done in 222 cases with various kinds of heart diseases, especially with special references to the feature and mechanism of the splitting of second heart sound and comared to the normal subjects. 2) Incidence of the splitting of the second heart sound was highest in PS, ASD with PS, ASD and RBBB (100 per cent in each group) and followed by VSD (97 per cent). Time interval of the split two component was ranged 0.08 2 sec. in PS, 0.081 sec. in ASD with PS, 0.053 sec. in ASD, 0.04lsec. in VSD, 0.019sec. in MS, 0.0 14 sec. in MI and 0.032 sec. in normal group. 3) In ASD group, neither of cardiac output or stroke output correlated well to the degree of the splitting, although, stroke index (stroke output/BSA) has shown significant correlation to the splitting time. 4) The ASD cases were classifired into three groups ; group A had stroke index of less than 130cc/min/M² and the diameter of right descending pulmonary arterial branch in A-P skiagram, and the splitting time was correlated well to the stroke index, group B had stroke index of less than 130cc/min/M² with diameter of pulmonary arterial branch of more than 1.5 cm and with considerable pulmonary hypertension, group C had stroke index of more than 1 30 cc/M2 with diameter of pulmonary arterial branch of more than 1.5cm and with rather normal pulmonary arterial pressure. Its split-ting time was less than 0.075sec. which showed no correlation to stroke index. 5) After successful surgical repair, the interval of the splitting showed the tendency to return to normal in all cases, yet, all surgical repaired ASD cases have still shown the split-ting more than 0.04sec. 6) Mechanism of the split second sound in ASD has been concluded to be due to the in-crease in stroke index or right ventricular ejection time in group A.

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Characteristics of the spatial vectorcardiogram were examined for the purpose of being applied to automatic diagnosis of the ECG. Analysis was made of intraventricular conduction time, maximum spatial magnitude, polar vector, planarity of the spatial loop, coordinate transformation of reference frame, and orientation of initial vector. A computer analysis was contrived so that parameter value might be automatically obtained. The spatial VCG'S with various findings were successfully characterized by parameter values obtained in the present study. These parameters may be recommended in automatic differential diagnosis of the ECG by the computer.

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Although there are numerous publications now in the literature on the pathogenesis of experimental hypertension, the mode of the development of cerebral hemorrhage has attracted little attention. In our laboratory a vascular permeability factor was demonstrated in the kidney cortex and we have reached to the working hypothesis that this factor might play an important role in the development of cerebral hemorrhages. It is the purpose of this report to clarify the property of the vascular permeability factor and its role in the development of vascular lesions in experimental animals. Materials and Methods 1. Production of experimental hypertension. Male rabbits weighing from 2.0 to 3.4 Kg were used in all experiments. A silver clip of 0.65 mm in diameter was applied to the right renal artery and after one week a 1.1 mm silver clip was applied to the left renal artery. They were divided into two groups. One group was given 10 per cent dehydrated lanolin (GB+L group), and the other was the control group (GB group). Blood pressures were measured in the central artery of the ear. 2. Preparation of vascular permeability factor from kidney cortex. After rabbit kidneys were perfused with physiological saline and heparin solution mixture, the cortex was precisely separated from the medulla and cut into small pieces about 2 to 3 mm in thickness. Hemoglobin was completely washed out with ice-cold physiological saline and the extract was made up by homogenization with twice the volume of distilled water. The homogenate was left overnight at 4'C for extraction, centrifuged at 40, 000 G for 30 minutes and then the supernatant was re-centrifuged at 100, 000 G for 60 minutes. The vascular permeability factor was further purified by chromatography on Sephadex G-100 column.

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