|Budget Amount *help
¥2,200,000 (Direct Cost : ¥2,200,000)
Fiscal Year 1996 : ¥300,000 (Direct Cost : ¥300,000)
Fiscal Year 1995 : ¥1,900,000 (Direct Cost : ¥1,900,000)
Study Objective : We pulse-wave velocity along the aorta before and after the vessel being replaced with artificial graft, in order to obtain information of the vessel-wall characteristics.
Subjects : Five patients who underwent replacement of diseased aorta by artificial graft as elective procedure.
Methods : Cardiosonogram at the aortic valve (the second intercostal space at left sternal edge), pulse-wave sensors at carotid artery and left femoral artery were monitored. From these informations, the time for the pulse to travel from the aortic valve to the femoral artery was determined. Actual lengths of the grafts were estimated from the operating records. From these variables, the original pulse wave velocity of the patients own vessels and the velocity along the graft were estimated.
Results : The velocity increased markedly after the replacement, together with the velocity along the graft were estimated.
Other parameters, including the hemodynamic parameters, hematocrit and blood gase
s, show no marked difference between the two measurements.
Discussions : Pulse wave velocity was found to be much faster along artificial graft than petients' own vessels. Generally speaking pulse wave velocity is pararell to the stiffness or elastance of the vessel wall ; the stiffer the wall, the faster the velocity. While stiffness is partly dependent upon the tension exerted from the pressure inside the tube, or blood pressure, it is determined mainly by the physical property of the material of the vessel wall. Our analysis indicates that the graft is many times stiffer than human vessels. We do not know why this is so, whether this should be so, or what the consequences would be. As the velocity data before grafting indicate, the patients own vessel wall was stiffer than normal subjects, yet the graft was even stiffer.
Conclusion : Pulse wave velocity along the aortic graft by artificial material is many times faster than that along the ordinary vessel. It indicates that the material used is much stiffer than the ordinary vessel. Less