Measurement of pressure half time in aortic regurgitation
Continuous wave tracing taken from the apical five chamber view illustrating the measurement of pressure half time (P1/2t) in aortic regurgitation. Here the Vmax (maximum velocity) is 479 cm/s and the slope of the Doppler tracing is 310 cm/s. Pressure half time is calculated from the slope using an algorithm by the computer of the echocardiograph. Here the pressure half time 453 msec. Pressure half time below 250 msec would suggest severe aortic regurgitation. Systemic vascular resistance, and aortic and left ventricular compliance can also influence the pressure half time, other than the severity of aortic regurgitation.