Hemodynamics - Part 1: Arterial

Arterial major descriptors

• flow direction

• phasicity

• resistance

Antegrade (floward flow)

blood flows in normal direction

Retrograde (reverse)

Blood flows opposite to normal direction

Bidirectional (to-fro)

blood flow enters and leaves a contained space via same orifice

Absent

No blood flow is detected with absent spectral doppler signal

Run off arteries

Lower leg or forearm artery

Multiphasic (biphasic, triphasic)

waveform crosses baseline and contains forward and reverse velocity components

Monophasic

waveform doesn’t cross baseline throughout any part of cardiac cycle/single direction

High resistive

sharp upstorke, bisk downstroke, with or without diastolic flow

Intermediate resistive

visible presence of dicrotic notch and continuous forward flow in diastole and contains rapid deceleration at end systole suggesting vasodilation

Low resistive

prolonged downstroke in late systole and diastole and continuous forward flow through diastole with presence of pandiastolic flow without presence of dicrotic notch

Rapid upstroke

nearly vertical slope or steep rise to peak systole. AT < 140 ms

Prolonged upstroke (tardus, delayed)

Abnormally gradual to peak systole. AT > 140 ms

Sharp peak

sharp, single, well-defined peak, often with maximum velocity within range of artery

Spectral broadening

Widening of velocity band in the spectral waveform; a ‘filling in’ of clear ‘window’ under systolic peak

absence of turbulence

Spectral broadening is commonly seen in turbulent flow but can also be seen in

Staccato

a very high-resistance pattern with a short ‘spike’ of velocity acceleration and deceleration followed by short and low-amplitude diastolic signal reflecting low antegrade flow

Dampened (attenuated, blunted)

combined finding of an abnormal upstroke (delayed) and peak (broad), often with decreased velocity

Flow reversal (pre-steal, competitive, oscillating)

flow that changes direction, not part of normal diastolic flow reversal, which may be transient or consistent with each cardiac cycle

High resistant triphasic waveform

• rapid antegrade flow during peak systole

• transient reversal of flow in early diastole

• slow antegrade flow in late diastole

Low resistance waveform

antegrade flow throughout systole and diastole

Normal resting inflow arteries

Supplying blood to vascular bed (common, external, IIA, innominate, and subclavian)

spectral bandwidth

is narrow in inflow arteries consistent with laminar flow

internal iliac artery

minimally increased spectral broadening and smaller vessel diameter may be noted in

analog CW waveforms

spectral bandwidth and broadening are not applicable to

normal resting outflow arteries

Carries blood away from region (CFA, prof a, superior fem a, pop a, axillary, and brachial)

PSV

in outflow arteries there may be a slight decrease in

normal resting run-off arteries

ant tibial, post tibial, peroneal, radial, and ulnar

normal resting plantar, palmar, and digital arteries

flow remains laminar with slight PW spectral bandwidth

exercise and increased temp

increase flow and PSV and decrease resistance are associated with

normal cca

minimal or no reverse flow and high diastolic flow from effect of low resistive ICA

Normal ECA

reverse flow phase in late systole and early diastole and mulitphasic flow showing high resistance

carotid bulb

flow separation along outer wall separating rapid forward flow along inner wall (boundary layer separation)

Normal proximal ICA

forward flow throughout cardiac cycle

normal mid ica

forward flow throughout cardiac cycle and relatively high diastolic flow showing low resistance

normal distal ica

forward flow throughout cardiac cycle and relatively high diastolic flow with increase PSV and vessel tapering

normal vertebral artery

forward flow throughout cardiac cycle and relatively high diastolic flow similar to ICA

Normal celiac (fasting or postprandial)

constant forward flow throughout systole and diastole with antegrade, resistive, and monophasic waveform

Normal sma fasting

waveform is antegrade, high resistive, and multiphasic with early diastolic flow reversal

normal sma postprandial

velocity increases in bosh systole and diastole while flow direction remains antegrade but waveform becomes low resistive and monophasic

normal renal artery

flow in normal main and accessory artery is antegrade, low resistive, and monophasic

PRF or scale

waveform should span to half to ¾ in height

wall filter

filter our low frequency shifts produced from vessel wall motion and tissues

high gain

can produce artifactual spectral broadening and lead to overestimation of PSV and EDV

high wall filter

can exclude vital information (low shifts, flow reversal, appear as floating waveform)

proper gain

enhances spectral doppler envelope and window

>0.7

Normal high resistive artery index (eca, extremity arteries, mesenteric arteries)

0.55-0.7

low resistive arteries index (ICA, hepatic, renal, testicular)

resistive index

peak systole - lowest diastole/peak systole