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Vascular sonography
Carotid Part 3- Indication, Pathology, and Interpretation
| Question | Answer |
|---|---|
| Indications for Extracranial Duplex exam? | Asymptomatic neck bruit, HX (DM, HTN, smoking & hyperlipidemia), Hx stroke, TIA, Screening prior ro syrgery, & Follow up after carotid endarterectomy or stenting |
| What are some Cerebrovascular Symptoms? | Reduction of flow due to high-grade stenosis (Arteries can become thick, not elastic), Emboli from atherosclerotic plaques (Ulcerated plaque increases risk, Can cause thromboembolic event), Arterial thrombosis (blood clot adhering to plaque) |
| What is a TIA? | Transcient ischemic attack- Neurologic deficits which occur intermittently, lasting from several minutes to a few hours, Symptoms resolve within 24 hours |
| What is RIND? | Reversible ischemic neurologic deficit- Neurologic deficits that last between 24 & 72 hours |
| What is CVA or completed stroke? | Cerebrovascular accident- Fixed or permanent neurologic deficits |
| What is paresthesia? | Focal weakness (paralysis) or numbness/tinging- Involving combination of face, arm, and leg on one side, Opposite to the affected cerebral hemisphere |
| What is dysphasia, or aphasia? | Difficulty speaking, Dysphasia(impaired), Aphasis (absent) |
| What is Amaurosis Fugax? | Shade drawn over eye- Partial blindness, Same side as responsible carotid lesion (ipsilateral) |
| What are the symptoms of Vertebrovacular insufficiency? | Less specific than carotid circulation symptoms, Dizziness/Vertigo (difficulty maintaining equilibrium), Diplopia (double vision), Ataxia (Muscular incoordination) |
| Where does plaque most commonly occur? | At the CCA bifurcation |
| What are the early stages of Plaque? | Plaque appears as thickened area of the intimal-medial layers, "Fatty Streak"-thin layer of lipid material, Fibrous cap may form between plaque and lumen |
| How can plaque be classified? | Smooth or irregular, and Homogenous or heterogenous |
| What will the waveform distal to stenosis look like? | Dampened, decreased flow velocity, and Delayed acceleration, rounded peak, "Tardus Parvus" |
| Waveform Proximal to Stenosis? | With V significant stenosis, proximal waveform will display a more high resistance pattern, Deccreased or absent diastolic flow, "Resistive Spectra" |
| What is the string sign? | Blunted, somewhat resistive waveforms that precede complete occlusion, Most commonly found in ICA |
| Distal ICA stenosis or occlusion Associated with the following findings in ICA? | Decreased diastolic flow or resistive component, Overall "blunted" appearing waveform -Important to compare bilaterally ICA end diastolic velocities |
| ECA stenosis? | Lesions tend to involve origin and proximal segments, Associated with: Focal veocity increase, Post-stenotic turbulence, and Dampened distal waveform |
| CCA Stenosis? | Can occur Prox, Mid, or Distal, Significant stenosis associated with: Focal Vel increases, Poststenotic turbulence, Dampened distal waveforms in both ICA and ECA, "Choke lesion" may result in retrograde ECA to supply ICA |
| Resistive or blunted waveforms indicate what? | Distal stenosis or occlusion |
| What is a Steal? | Steal is a situation where one vascular bed draws blood away or steals from another |
| What does the degree of steal depend on? | Severity of stenosis, Resistance offered by the various downstream vascular beds |
| What is a subclavian steal? | Hemodynamically significant sten in proxs ubclavian art causing changes to vertebral art flow- results in brachial blood pressure ↓ on affected side(more than 15 to 20 mmHg lower than contralateral arm) |
| What does a subclavian steal cause? | Causes ↓ pressure at the origin of ipsilateral vertebral artery that can lead to reversed flow |
| How does Vertebral artery flow change as obstruction progresses? | Normal Antegrade flow, Antegrade flow with deep notch mid-cardiac cycle, Alternating or bidirectinal (to-and-fro) flow, Complete reversal (fully retrograde) flow |
| What is a Latent Steal? | Flow that is beginning to show signs of reversal but not completely retrograde, WF characteristics can be: hesitant(deep flow reversal notch), Alternating or bidirectional |
| What is a Complete Steal? | Complete retrograde flow of vessel involved, W/ Severe subclavian art stenosis, the vertebral artery will reverse in order to provide blood flow to the arm |
| Is surgical intervention typically done with a complete occlusion of one side in the carotid system? | No because not an embolic risk anymore is complete occlusion |
| What does NASCET stand for? | North American Symptomatic Carotid Endarterectomy Trial |
| What is the criteria for NASCET? | >70% stenosis defined as (ultrasound), PSV >230 cm/s, ICA/CCA ratio >4.0, Highest PSV from stenotic ICA, CCA PSV from normal mid-to-distal segment |
Created by:
EmilyGriffin
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