Analysis of waveforms has, historically, served as the basis for noninvasive
diagnosis of vascular disease. In attempting to understand the blood flow
patterns associated with vascular disorders, investigators have assessed the
morphology of waveforms recorded directly or indirectly from tissues and blood
vessels by a variety of instruments. Phonoangiography, plethysmography, analogue
recordings of continuous wave Doppler signals, and analysis of spectral
waveforms recorded with pulsed Doppler have all been used for diagnosis of
vascular disease. Decades of research with these instruments have revealed much
about the nature of normal and abnormal blood flow patterns. Even so, clinicians
in modern vascular laboratories are often confounded by alterations in waveform
morphology and the characterization of waveforms remains controversial. In this
and following articles, Dr. Beach and other experts in the field of noninvasive
vascular diagnosis take us on a journey from where it all began to the present
day, allowing us to take a look at what we now know and, most importantly, the
questions that still remain.