Continuous wave Doppler echocardiography and coarctation of the aorta: gradients and flow patterns in the assessment of severity.

Indices of the severity of coarctation derived from non-invasive Doppler echocardiography were compared with measurements derived from cardiac catheterisation and angiography. In 24 Doppler studies from 17 children instantaneous peak systolic and diastolic gradients and time to half peak systolic and diastolic velocities were compared with the ratio of the coarctation diameter to the diameter of descending aorta at the level of diaphragm obtained from angiographic systolic frames of the aorta. A high peak systolic gradient (greater than 40 mm Hg) or long time to half peak diastolic velocity (greater than 100 ms) (that is, maintenance of flow in diastole) were both highly specific (100%) in detecting coarctation of the aorta where the angiographic ratio was less than or equal to 0.5. Diastolic measurements, however, were more sensitive (79% both for peak diastolic gradient and for time to half peak diastolic velocity) than systolic (57% for peak systolic gradient and 64% for time to half peak systolic velocity). Even higher sensitivity (93%) was obtained when the peak systolic gradient was greater than 40 mm Hg or the time to half peak diastolic velocity was greater than 100 ms. Examination by continuous wave Doppler echocardiography is an effective non-invasive method of assessing the severity of coarctation of the aorta, particularly when systolic and diastolic events are considered together. This approach overcomes the relatively low sensitivity of peak systolic gradient alone.