| Project/Area Number |
61570428
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Circulatory organs internal medicine
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| Research Institution | Tokai University |
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Principal Investigator |
TOSHIO NAKAMURA Tokai University School of Medicine, 医学部, 助教授 (00004739)
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| Project Period (FY) |
1986 – 1987
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| Project Status |
Completed (Fiscal Year 1987)
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| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1987: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1986: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Keywords | Cardiac hypertrphy / Ledt ventricular function / Myocardial oxygen consumption / Left ventricular mechanical eddiciency / Concentric hypertrophy / 左室肥大 / 心機熊 / 大変形理論 / 外的仕事効率 |
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| Research Abstract |
The effect of the concentric hypertrophy on left ventricular function was studied in five pressure-overloaded canine heart. The study was done using the excised left ventricle which was supported metabolically by a donor dog. The end-diastolic pressure of the preparation was set at 20 mmHg. In the pressure-overloaded ventricle, the end-diastolic volume was smaller by 47 % (p < 0.01) and the peak systolic pressure was higher by 24 % (p < 0.01) than the control at isovolumic beats. Ejection pressure was controlled by newly developed afterload controlling system at various levels and kept constant during the ejection phase. In the pressure-overload ventricle, the slope (the reciprocal is Emax) of the regression Line of the end-systolic volume on ejection pressure decreased (p < 0.01) to 0.095 ml/mmHg by 47 % from 0.186 ml/mmHg in the control. The volume-axis intercept (Vd) of the line was reduced to 55% of the control. A decrease in the regression line slope was in linear proportion to th
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e degree of concentric hypertrophy, namely, to the change in chamber geometry. These results indicated that: (1) Despite reduction of the end-diadtolic volunme, the concentric hypertrophied ventricle showed no reduction in stroke volume at the same level of ejection pressure, because of its improved capability to generate pressure. (2) Emax was dependent on ventricular geometry.
The effect of the occurrence of concentric hypertrophy on left ventricular mechanical efficiency (EME) and that of the myocardial hypertrophy on myocardial oxygen consumption (MVO2) was studied. There was a relation of parabolic function between the external mechanical work-and-efficiency and LV ejection pressure. The maximal value of LVW and EME in hypertrophied hear did not change significantly as compared with that in the controls. However, the maximal value of LVW and EME were obtained at a higher ejection pressure in hypertrophied heart. The following result was also obtained that the converting efficiency from that the converting efficiency from chemical energy in hypertrophied myocardium remains unchanged after the occurrence of hypertrophy. Less
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