Chapter 7: The Extracranial Duplex Ultrasound Examination Flashcards
(169 cards)
an abnormal “blowing” or “swishing” sound heard with a stethoscope while auscultating over an artery, such as the carotid. The sound results from vibrations that are transmitted through the tissues when blood flows through a stenotic artery.
bruit
A slight dilation involving variable portions of the distal common and proximal internal carotid arteries, often including the origin of the external carotid artery. This is where the baroreceptors assisting in reflex blood pressure control are located.
carotid bulb
Most commonly defined as the angle between the line of the Doppler ultrasound beam emitted by the transducer and the arterial wall (also called the “angle of insonation”). This is a key variable in the Doppler equation used to calculate flow velocity.
Doppler angle
The location along the ultrasound beam where a pulsed Doppler detects flow. The size and the depth of the sample volume can be adjusted by the examiner to allow evaluation of flow at any site in the B-mode image.
sample volume
A signal processing technique that displays the complete frequency and amplitude content of the Doppler flow signal. The spectral information is usually presented as waveforms with frequency (converted to a velocity scale) on the vertical axis, time on the horizontal axis, and amplitude indicated by a grayscale.
spectral analysis
An increase in the “width” of the spectral waveform (frequency band) or “filling in” of the normally clear area under the systolic peak. This represents turbulent blood flow associated with arterial lesions.
spectral broadening
An episode of stroke-like neurologic symptoms that typically lasts for a few minutes to several hours and then resolves completely. This is caused by a temporary interruption of the blood supply to the brain in the distribution of a cerbral artery.
transient ischemic attack (TIA)
Normal ICA PSV
<125 cm/s
Extensive plaque, often with acoustic shadowing due to calcification
PSV >125 cm/s and EDV > 140 cm/s
Severe (80-99%) ICA stenosis
Retrograde of “hesitant” flow in the ipsilateral vertebral artery
subclavian steal
brachial systolic pressure gradient >15 mmHg
Subclavian steal
minimal or no spectral broadening; flow separation present in the carotid bulb
Normal ICA
spectral broadening during deceleration phase of systole only
1% - 15% occlusion
spectral broading throughout systole; plaque
16-40% occlusion
mark spectral broadening; plaque
80-90% occlusion
No flow signal in the ICA; decreased or absent diastolic flow in the ipsilateral CCA; plaque or thrombosis in the ICA lumen; diffusely increased PSV in contralateral carotid system
100% occlusion
Primary goal of noninvasive testing for extracranial cerebrovascular disease
identify patients who are risk for stroke due to athersclerotic plaque
Secondary goal on nonvasive testing for extracranial cerebrovascular disease
document progressive disease in patients already known to be at risk or recurrent stenosis after intervention
Major indications Carotid exam
asymptomatic neck bruit
hemispheric cerebral or occular transient ischemic attacks
history of stroke
screening before major peripheral vascular
Only about ___ of bruits are related to high-grade internal carotid stenoses
1/3
sometimes referred to as a “mini stroke?
TIA
characterized by
focal weakness
numbness
aphasia
TIA
also known as cerebrovascular accident
stroke
provide best image resolution; most options for Doppler angle correction
linear array transducer 12-3MHz