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Haemodynamic evaluation of carotid artery disease
1Department of Vascular Surgery, Rigshospitalet, University of Copenhagen, Denmark.
Insights
Assessing cerebral hemodynamics is crucial for internal carotid artery (ICA) stenosis. Non-invasive Doppler methods can accurately evaluate hemodynamic changes, identifying patients with reduced blood flow pressure.
Area of Science:
- Neurology
- Vascular Surgery
- Medical Imaging
Background:
- Cerebral ischemia from internal carotid artery (ICA) stenosis can result from embolism or hypoperfusion.
- Severe ICA stenosis may be compensated by collateral circulation, but this capacity is often insufficient.
- Current studies often focus on diagnosing ICA lesions rather than their hemodynamic impact.
Purpose of the Study:
- To review non-invasive methods for hemodynamic evaluation of carotid artery disease.
- To identify techniques capable of assessing cerebral hemodynamic changes induced by ICA stenosis.
Main Methods:
- Review of non-invasive techniques including Doppler waveform analysis, cerebral blood flow (CBF) reactivity tests, periorbital Doppler, and transcranial Doppler.
- Evaluation of methods for their accuracy in assessing hemodynamic changes and pressure gradients.
Main Results:
- Doppler waveform analysis and CBF reactivity tests can identify patients with significantly reduced ICA perfusion pressure.
- Periorbital Doppler and Ocular Plethysmography (OPG) detect ICA lesions but cannot differentiate pressure reduction severity.
- Combined periorbital Doppler and distal ICA waveform analysis effectively rule out severe pressure reduction in cases of orthograde flow.
Conclusions:
- Non-invasive methods, particularly Doppler-based techniques, can accurately assess the hemodynamic significance of ICA stenosis.
- Analysis of distal ICA waveforms is crucial for identifying severe pressure reduction, especially in cases of inverted flow.
Abstract:
Cerebral ischaemia in the region of an internal carotid artery (ICA) stenosis may be caused by embolism or cerebral hypoperfusion. A severe ICA stenosis may be well compensated by collateral blood supply, however, in some patients the capacity of the collateral blood supply is insufficient. Studies evaluating therapeutic modalities or natural history of carotid artery disease should therefore include a test capable of assessing cerebral haemodynamics. However, most studies, invasive as well as non-invasive, have focused on the ability of the test to diagnose the ICA lesions itself, rather than the haemodynamic changes induced by the stenosis. This paper reviews non-invasive methods for haemodynamic evaluation of carotid artery disease. Haemodynamic evaluation of ICA stenoses may be performed accurately by different techniques. Analysis of Doppler waveforms obtained distal to the ICA lesion and CBF reactivity tests may identify patients with severe reduction in ICA perfusion pressure. Periorbital Doppler examination and OPG identifies ICA lesions causing minor pressure gradients, however, they are unable to discriminate between minor and moderate to severe pressure reduction. Transcranial Doppler examination may prove to be useful in haemodynamic assessment of ICA stenoses, but, this remains to be evaluated. Presently, in addition to direct evaluation of the carotid arteries, we use a combination of periorbital Doppler examination and analysis of distal ICA waveforms. In cases of an ICA stenosis and orthograde flow any severe pressure reduction may be ruled out. In cases of inverted flow, analysis of distal ICA waveforms may identify patients with severe reduction in ICA perfusion pressure.