deceleration time to pressure half time
Pressure half time is the time required for the peak pressure gradient to reduce by half (1/2) which will correspond to a decrease in peak velocity by a factor of square root of two (21/2). Pressure half time of a regurgitant jet depends on the severity of the regurgitation and the compliance of the receiving chamber.
The deceleration time is another simple means of evaluating the MV area, in which decay of the mitral inflow profile through a stenotic MV is examined. The following formula describes the relationship of the deceleration time to the MV area (19):