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Figure 3 (A) Free body diagram of the mitral valve complex. In an equilibrium condition of the closed mitral valve complex in systole, mitral leaflet force balance (below the dashed line) requires that the transmitral pressure forces (F_p,i) are counteracted by the chordal tethering force, F_T (equal to –F_C) and the annular tethering force, F_A. Chordal force balance (above the dashed line) requires that the coapting force component F_C is counteracted by an equal and oppositely directed tethering force from the papillary muscle attachment, F_T. Transmitral pressure forces and F_A are only presented for schematic and conceptual purposes and were not assessed in the study. (B) The chordal force measure of each chorda tendinea consisted of the chordal tethering force component (F_T) and the chordal coapting force component (F_C). The difference of the force components, (F_C – F_T), defined the resulting (valvular directed) force of the chorda tendinea acting on the leaflets at the point of insertion.