Step
1: Obtain a PWD the VTI of the LVOT. The
dp/dt is the rate of pressure change using the 4V2
formula over time during isovolumic contraction.
During isovoumic contraction the pressure dramatically
increases. To measure the RATE of the pressure
increase, a mitral regurgitant jet is required.
The time for the pressure to increase where the
velocity of the mitral regurgitant jet changes from
1 m/sec (4 mmHg) to 3 m/sec (36 mmHg) is the dp/dt.
This 32 mmHg pressure change occurs before the aortic
valve opens and before significant left ventricular
volume has been ejection. The pressure difference
divided by the time difference will yield the dp/dt.
The rate of the dp/dt is an indication of the contractility
of the left ventricle as a whole.
