"In a non-obstructed mitral valve flow velocities are low. Significant energy is expended in accelerating the flow (flow acceleration). As the flow velocity is low, energy associated with convective acceleration is low. As viscous losses in this situation are minimal, the other two components (flow acceleration and convective acceleration) of the Bernoulli equation have to be taken into account. In the simplified Bernoulli equation, the flow acceleration component is ignored. Put simply, when you deal with low-velocity signals in pulsatile system, the simplified Bernoulli equation does not describe the pressure flow relationship accurately"-- Provided by publisher.