THE CHANGE IN THE LEFT VENTRICOLAR STIFFNESS AND VISCOSITY AFTER ISCHAEMIA

Research Project

Project/Area Number	06671355
Research Category	Grant-in-Aid for General Scientific Research (C)
Allocation Type	Single-year Grants
Research Field	Thoracic surgery
Research Institution	KYOTO PREFECTURAL UNIVERSITY OF MEDICINE
Principal Investigator	TODA Shogo K. P. U. M., Dept. of Med., 医学部, 助手 (80201656)
Co-Investigator(Kenkyū-buntansha)	SOHMA Akira K. P. U. M., Dept. of Med., 医学部, 助手 (20254352)
Project Period (FY)	1994 – 1995
Project Status	Completed (Fiscal Year 1995)
Budget Amount *help	¥2,100,000 (Direct Cost: ¥2,100,000) Fiscal Year 1995: ¥600,000 (Direct Cost: ¥600,000) Fiscal Year 1994: ¥1,500,000 (Direct Cost: ¥1,500,000)
Keywords	Diastole / Cardiac Function / Stittness / Viscosity / Ischaemia
Research Abstract	Myocardial stunning is a state of deteriorated cardiac function following an ischaemic insult despite the reestablishment of coronary flow. It is associated with very limited evidence of morphological and biochemical abnormalities. Therefore it is difficult to determine immediately after the reestablishment of coronary perfusion as a result of the treatment for ischaemia whether the heart is in a 'recuperative' stunning state or irremediable course to infarction. One proposed mechanism concerns defects of the collagen matrix. If so, it might be possible to observe the accompanying changes in physical properties of the heart while the cell structure is damaged. In this study we investigated the diastolic regional stiffness and viscosity. Six canines were subjected to regional ischaemic insult resulting in cardiac stunning. Measurement was performed one and two hours after coronary flow was reestablished at both ischaemic and non-ischaemic region. Stiffness and viscosity were calculated from the data at the end-diastolic period of each cardiac cycle using the equation described below ; F= c・exp (Kp・L)+ η・ (dL/dt), where, F ; regional force, L ; regional circumferential length, Kp ; stiffness, η ; viscosity, c ; constant, respectively. Fractional shortening was reduced significantly after the coronary occlusion despite the reestablishment of coronary flow. Regional viscosity was increased significantly at the ischaemic region as early as one hour after the start of reperfusion, whilst the stiffness remained unchanged.