To find a clue to the treatment, pathophysiology of myocardial infarction with pump failure was studied. Pump failure was divided into two subsets, pump failure immediately after the initial attack and pump failure over two weeks after the initial attack. In each subset, characteristics of pump failure in myocardial infarction were discussed.

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Dynamics of renin-angiotensin (RA) system under various conditions was studied in 8 hypertensive patients due to segmental renal ischemia. The ischemia in the kidney of these patients was localized lesion, involving only 10-30% of the affected kidney. Increased level of peripheral vein renin activity (PVRA) at basal condition was found in half of them. Irrespective of their resting PVRA, they responded to various renin secreting stimuli with more remarkable enhancement of PVRA than control group. Significantly higher renal vein renin activity was estimated on the affected side compared with that of the unaffected. Localized increase in renal renin content was proven in the ischemic area of the kidney. From these results, it may be concluded that RA system is etiologically related to the pathogenesis in this type of hypertension and that careful renin studies are practically useful to diagnose a small, but functionally significant, ischemic process in the kidney.

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Echocardiographic, hemodynamic and angiocardiographic studies in 11 patients with pure mitral insufficiency were carried out with special reference to the correlation of the amplitude of motion of the anterior mitral valve with total stroke volume, regurgitant volume, regurgitant percent and ejection fraction respectively, and of the descent rate of the anterior mitral valve with total stroke volume, mean mitral valvular flow during diastole and Ry/v respectively. The characteristic findings of mitral valve echogram in mitral insufficiency were the increase in amplitude father than the increase in the descent rate of the anterior mitral valve. On the basis of echocardiographic findings patients with mitral insufficiency were classified into three groups. The increase in amplitude may be assumed due to the increase in total stroke volume, but no correlation was found between total stroke volume and amplitude, while positive correlation between amplitude and ejection fraction was found. Positive correlation between the descent rate of the mitral valve echogram and Ry/v was found. From these results it is suggested that one of the factors affecting the descent rate is elasticity of left atrium and that one of the factors affecting amplitude is total stroke volume corrected for left ventricular end-diastolic volume (ejection fraction).

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In order to throw light upon the controversial mechanism of pulmonary hypertension associated with hypertensive shock due to acute pulmonary embolism, the following experiments were carried out. Strictly unilateral pulmonary embolization with Lycopodium spores was attempted in the dog, and the results were compared with those obtained by unilateral balloon occlusion of the ipsilateral pulmonary artery as the control. In addition, reccurrent embolizations with Lycopodium spores were also performed to observe a critical point at which lethal systemic hypotension would occur. Method s A suspension of Lycopodium spores in saline was prepared so as to be a mixture of 50 mg/ml. The adult mongrel dog was anesthetized with pentobarbital soda (an initial dose of 25 mg/kg) and heparinized. 1. A balloon tip catheter with an end hole was placed in the proximal left pulmonary artery. Effects of balloon occlusion of the left pulmonary artery on the pulmonary artery pressure was compared with that of strictly ipsilateral Lycopodium embolization, in the same animal. In order to evaluate the degree of obstruction of the blood flow, end-tidal CO₂ concentration from the left lung was continuously monitored employing a bronchospirometric tube. The systemic and pulmonary artery pressures were consistently recorded. To confirm that Lycopodium spores had not overflowed into the contralateral lung, a smear preparates obtained by means of incising of the right lung lobes were microscopically checked very carefully, in postmortem examination. 2. An initial dose of 100 to 200 mg of Lycopodium spores was injected into the right atrium, then a dose of 25 to 100 mg was added every 5 to 15 minutes in the same manner. In this series, the changes in the pulmonary and systemic artery pressures and the respiratory rate were observed. Results When strictly left pulmonary artery embolization was accomplished, the elevation in the pulmonary artery pressure never exceeded that observed in the control balloon occlusion of the ipsilateral pulmonary artery. In this group, the elevation in the pulmonary artery pressure by superimposed balloon occlusion after embolization was as same in the degree as by the control occlusion. No or negligible overflowing of Lycopodium spores into the right pulmonary artery was confirmed by the postmortem examination (10 experiments).

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