LEA Waveforms

Stroke Volume

amount of blood ejected from the heart every beat; measured as liters/beat

Stroke Volume Equation

EDV-ESV

Cardiac Output

volume of blood ejected by the heart per minute

Cardiac Output Equation

SV x HR

Pre Load

amount of blood left in ventricle at the end of diastole

After Load

resistance against which the ventricle must pump

Cardiac Cycle

pressure wave created by each stroke volume of blood

Pulsatile Wave

variations in blood volume and energy occuring during each cardiac cycle

Cardiac and Venous Flow

-IVC to RA

-increase P RA, blood to RV

-increase P RV, blood to pul art

-blood to lungs

-oxygen into blood

-pul vns to LA

-increase P in LA

-blood to LV

-blood dispersed to arterial system

Cardiac and Arterial Flow

-LV pressure > aorta

-BP rises in aorta

-arterial walls expand

-arterial reservoir

-diastole: walls relax and blood propelled

Spectral Doppler

-analyzes how all the RBCs are moving at a particular point in time

-movement of RBC is evaluated and displayed on a graph

-doppler signal is in the audble range the spectral display adds a visual representation (20Hz- 20kHz)

Spectral Doppler

-presence of flow

-direction of flow

-flow characteristics

SD Direction of Flow

relative to the position of the trace on the baseline

SD Flow Characteristics

-peak velocity of flow and thickness of the trace indicate normal/abnormal hemodynamics

-vessel resistance (high or low)

-magnitude (mean)

SD Flow Direction

-doppler shift is the difference btwn transmitted and recieved frequency

-flow away from doppler beam is negative flow and is displayed below the baseline (unless inverted)

-flow towards doppler is positive flow and is above the baseline

Spectral Doppler

-flow direction is shown in relation to spectrum baseline and color bar

-velocity: PSV and EDV

-pulse repetition frequency

Y/Vertical Axis

velocity

X/Horizontal Axis

time

Z Axis

magnitude/characteristics, distribution of velocities

Z Axis

-each pixel corresponds to a specific moment in time or specific frequency shift or velocity

-brightness of a pixel is proportionate to the # of blood cells causing the frequency shift at that specific point in time

SD White

large number of blood cells have the corresponding velocity at that moment in time

SD Black

no or few blood cells have the corresponding velocity

SD Gray

moderate number have corresponding velocity

Fast Fourier Transformer

-mathematical formula designed to break down a complex waveform into various frequency components

-signal is digitized and mathematically analyzed to determine the individual frequency range

-displayed on a graph as a function of time showing the relative amplitude of the frequencies

FFT Advantages

-exceedingly accurate

-displays all individual velocity components that make up the complex reflected signal

-distinguishes between laminar and turbulent flow

Waveform

shape of the wave that is produced by the heart over the cardiac cycle

Systole

initial contraction phase, peak velocities

Diastole

relaxation phase, lowest velocities

Zero Baseline

signifies flow direction

End Systolic Notch

rapid deacceleration of systole and rapid acceleration of diastole

Flow Direction

movement of blood

Antegrade

forward flow, normal

Retrograde

reversed flow, abnormal

Bidirectional

both forward and reversed

Absent

flow not present

Antegrade

Retrograde

Bidirectional

Absent

Phasicity

changes in flow direction

Multiphasic

crosses the baseline and has forward and reversed flow components

Monophasic

does not cross baseline and has continuous forward flow

Zero Baseline

Multiphasic

Monophasic

Resistance

any type of impediment to flow

High Resistance

sharp upstroke/brisk downstroke

Intermediate Resistance

-sharp upstoke/brisk downstroke

-forward flow throughout

-end systolic notch

Low Resistance

broad downstroke and continual flow through out diastole

High Resistance

Intermediate Resistance

Low Resistance

Normal High Resistance

-infra renal aorta, CIA, EIA, IIA

-SMA/IMA Fasting

-CFA, DFA, SFA, Pop, ATA, PTA, Pero

-subclavian, axillary, brachial, radial, ulnar

-external carotid

Normal Intermediate Resistance

-supra renal aorta

-common carotid

Normal Low Resistance

-celiac, renal, SMA, IMA post prandial

-internal carotid, vertebral artery

-hepatic and splenic arteries

Laminar/Parabolic Flow

-faster in the middle/slower at the sides

-spectral trace is narrow during systole (blood cells accelerate together at similar velocites)

-spectral trace is thicker during diastole (blood cells are slowing down and do so at various velocites)

-anechoic spectral window

Laminar/Parabolic Flow

Spectral Broadening

-disruptive flow pattern

-indicative of disturbed or turbulent flow

-sample gate next to wall

-wide sample gate

-increased doppler gain

-filled in spectral window

Spectral Broadening

Dampening/Tardus Parvus

-upstroke/downstroke equal

-overall low velocities

-never normal (indicated stenosis proximal to insonation site)

Dampening/Tardus Parvus

Turbulence

-forward and reversed (bidirectional) flow

-marked spectral broadening

-variable velocities

-post stenosis

Turbulence

Disturbed/Flow Separation

-flow lines are slightly disrupted

-bulb, bifurcation, noncritcal stenosis

Disturbed/Flow Separation

Flow Jet

-maximum flow velocities across a narrowed segment

-velocity is correlated to the percentage of narrowing

-tightly narrowed segment = high velocities

Flow Jet

Occluded Flow

no flow present due to occlusion of artery

Occluded Flow