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Figure 1 (A) Continuous-wave Doppler across aortic coarctation with prominent "diastolic tail," the peak systolic velocity (SV), diastolic velocity at the end of ‘T’ wave (DV), and end-diastolic tail velocity at beginning of ‘Q’ wave (EDTV). (B) Systolic velocity half-time (SVHT), systolic pressure half-time (SPHT), diastolic velocity half-time (DVHT), and diastolic pressure half-time (DPHT). SVHT (ms): time taken for the systolic velocity to fall to half of its peak value; DVHT (ms): time taken for the diastolic velocity to fall to half of its value at the end of T-wave; SPHT (ms): time taken for the peak systolic pressure gradient (4[SV]²) to fall to half of its value; DPHT (ms): time taken for the diastolic pressure gradient (4[DV]²) to fall to half of its value.