Key result
CarboMedics valve closes faster with less closing volume than Björk-Shiley Monostrut during simulated atrial contraction.
Why the study?
The effect of atrial contraction on the dynamic behavior of mitral prosthetic valves was unclear and required clarification.
In an in vitro mock circulatory system, the CarboMedics prosthetic mitral valve demonstrated a better closure response with shorter closing time and less closing volume compared to the Björk-Shiley Monostrut valve under active atrial contraction.
In vitro closing advantages do not inform valve selection; clinical outcomes under active atrial contraction remain untested.
To clarify the effect of atrial contraction on the dynamic behavior of mitral prosthetic valves, a mechanical mock circulatory system has been developed. It is able to simulate the inflow characteristics during diastole. The disc motions of Björk-Shiley Monostrut (BSM29) and CarboMedics (CM29) valves (both with an annulus diameter of 29 mm) were measured and compared with a high speed video camera. After contraction of the artificial atrium (100 ms), there was a delay of 75 ms before the onset of the ventricular contraction. Mitral flow similar to physiological conditions could be achieved. The BSM29 was tested in the anterior position (a) and the posterior position (p). Under the condition of active atrial contraction (AC), we confirmed that the closing motion was initiated and the period during closing motion (PDCM) was prolonged (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 prolongation of the PDCM of the CM29 due to the AC being smaller than that of the BSM29. We also confirmed that the closing volume (CV) increased 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 produced better response at valve closure than the BSM29.
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Naemura et al. (1997) studied this question. CarboMedics (CM29) valve vs. Björk-Shiley Monostrut (BSM29) valve was evaluated on Period during closing motion (PDCM) and closing volume (CV) under active atrial contraction. In a mock circulatory system, the CarboMedics valve demonstrated a shorter period during closing motion and less closing volume compared to the Björk-Shiley Monostrut valve under active atrial contraction.
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