| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2002: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 2001: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2000: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Research Abstract |
Recently, arterial conduits, such as internal thoracic arteries and the right gastroepiploic artery are being used extensively for coronary artery revascularization to obtain better long-term patency. To use these grafts, end-to-side anastomosis (ESA) is generally utilized to attach the bypass graft to the native coronary artery. Due to the small caliber of these conduits, a slit must be made at the end of the graft to obtain a sufficiently large anastomotic area. However, with side-to-side anastomosis (SSA) a larger anastomotic area can be obtained for arterial conduits, and therefore we have been performing SSA clinically for coronary artery bypass grafting (CABG) with arterial grafts for several years. In this study, we conducted experiments on ESA and SSA to determine the performance and characteristics of these anastomotic methods, to provide practical information for surgeons and to facilitate the selection of anastomosis for individual patients.
Hemodynamic tests of the two diffe
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rent types of anastomoses (ESA and SSA) were carried out in both in vitro and in vivo settings. In the in vitro study, two different anastomotic models were constructed from transparent siliastic tubes, and hemodynamic parameters were measured using a mock circulation device. Moreover, we conducted a comparative study to support the in vitro data using numerical flow simulations. These simulations were validated against experimental data using the flow visualization technique. In the in vivo study, CABG was performed in five adult pigs under cardiopulmonary bypass. Bilateral internal thoracic arteries were inserted into the right coronary artery using ESA or SSA for each graft. After weaning from cardiopulmonary bypass, hemodynamic measurements were obtained, as in the in vitro study.
Energy loss was calculated from the graft flow rate and the pressure loss between the native coronary artery and bypass graft. In the in vitro study, the energy loss for SSA was 23.8% lower than that of ESA. This was reproduced in the in vivo study in which reduction of 44.8% was observed. The result of numerical analysis and flow visualization indicated the existence of a stronger vortex in ESA compared with SSA.
Less disturbance and lower flow resistance were observed in SSA than in ESA based on the level of energy loss and observation of flow fields, which suggests that SSA has a smoother anastomotic geometry for flow than ESA. This might affect the inhibition of intimal hyperplasia, which could lead to a better long-term patency rate of the coronary bypass conduit using SSA compared with ESA when arterial conduits are used. Less
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