A newly developed "Single-Valved Assist Device"-A combined pump for bypass and counterpulsation.

Research Project

Project/Area Number	60570649
Research Category	Grant-in-Aid for General Scientific Research (C)
Allocation Type	Single-year Grants
Research Field	Thoracic surgery
Research Institution	Jichi Medical School
Principal Investigator	KIMURA Sosuke Associate, Dept. of Thorac. & Cardiovasc. Surg., JMS., 医学部, 講師 (30118450)
Co-Investigator(Kenkyū-buntansha)	FUKUSHIMA Kanae Associate, Dept. of Thorac. & Cardiovasc. Surg., JMS, 医学部, 講師 (90049023) HARADA Mikio Assistant, Dept. of Thorac. & Cardiovasc. Surg., JMS, 医学部, 助手 (30156517)
Project Period (FY)	1985 – 1986
Project Status	Completed (Fiscal Year 1986)
Budget Amount *help	¥1,800,000 (Direct Cost: ¥1,800,000) Fiscal Year 1986: ¥500,000 (Direct Cost: ¥500,000) Fiscal Year 1985: ¥1,300,000 (Direct Cost: ¥1,300,000)
Keywords	Left Heart Bypass / Counterpulsation / Systolic Unloading / Tension Time Index / Man-machine interaction
Research Abstract	Lacking in the sufficient reduction of the pressure work of left ventricle, the partial LA-Ao bypass (LHB) should have some limits in assisting the failing heart. The addition of counterpulsation (Cp) could reduce the tension time index (TTI), but yielded a complicated interaction between the bypass and Cp. From this viewpoint, we developed a single unit device possessing both functions. The device (SVAD) is composed of a pulsatile chamber and a single valve at the inflow portion. It functions as a bypass pump with a massive regurgitation in the outflow. Under the synchronized use, this regurgitation, though lowering the efficiency of the bypass, makes a strong systolic unloading. Using 8 dogs, the effects of SVAD on the left heart failure (AoP<100mmHg, LAP>12mmHg, CVP=4.5-10cm <H_2> 0, HR=80/min) were examined, comparing with the conventional LHB under the same flow assist. Total of 56 experiments were performed and analyzed. In TTI, SVAD showed a distinct reduction of -20%, while -4% by LHB. In accordance with the increase of the bypassflow, SVAD showed a gradual and sufficient decrease in TTI, while LHB showed almost no change until the bypass rate reached to the total. Diastolic pressre time index / TTI was 2.1 and 1.6, respectively, under the assist. SVAD is a simple and doubly functioning assist device, having a favorable effect for the restoration of the natural heart by the TTI reduction.