Doppler probe placed over artery with use of gel – character of sound is considered
Normally – sharp and high pitched hissing sound during systole – should be triphasic or biphasic; second sound(s) is backward flow during diastole; small vessels may only be monophasic as too small for backward flow
Sounds become higher pitched when blood flow is greater eg narrowed vessel.
Steeper the waveform, the faster the blood flow.
Normal pattern is triphasic.
Limitation – Doppler signal cannot reliably penetrate atherosclerotic plaques