STUDY OF THE EFFECT OF ATRIAL CONTRACTION ON MITRAL PROSTHETIC VALVE BY HIGH-SPEED VIDEO CAMERA

To clarify the effect of atrial contraction on the dynamic behavior of mitral prosthetic valves, a mechanical mock circulatory system has be en developed. It is able to simulate the inflow characteristics during diastole. The disc motions of Bjork-Shiley Monostrut (BSM29) and Carb oMedics (CM29) valves (both with an annulus diameter of 29 mm) were me asured and compared with a high speed video camera. After contraction of the artificial atrium (100 ms), there was a delay of 75 ms before t he onset of the ventricular contraction. Mitral flow similar to physio logical conditions could be achieved. The BSM29 was tested in the ante rior position (a) and the posterior position (p). Under the condition of active atrial contraction (AC), we confirmed that the closing motio n was initiated and the period during closing motion (PDCM) was prolon ged (BSM29[a]: 22.4 +/- 3.4 --> 63 +/- 3.2; BSM29[p]: 71.2 +/- 38 --> 94.2 +/- 11; and CM29: 14 +/- 0.0 --> 28.4 +/- 2.3 [unit: ms]), the pr olongation of the PDCM of the CM29 due to the AC being smaller than th at of the BSM29. We also confirmed that the closing volume (CV) increa sed slightly (BSM29 [a]: 7.8 +/- 0.4 --> 8.5 +/- 0.8; BSM29[p]: 6.9 +/ - 0.6 --> 7.0 +/- 0.5; and CM29: 3.6 +/- 0.6 --> 4.1 +/- 0.6 [unit: ml ]). The CM29 had a shorter PDCM, less prolongation of the PDCM due to the AC, and less CV than the BSM29. Thus, we confirmed that the CM29 p roduced better response at valve closure than the BSM29.