Evaluation of cerebral circulation in patients with significant carotid artery stenosis
Anna Kabłak-Ziembicka1, Tadeusz Przewłocki, Piotr Pieniazek
1Institute of Cardiology, Collegium Medicum, Jagiellonian University, Kraków, Poland. kablakziembicka@op.pl
Insights
Patients with internal carotid artery (ICA) stenosis have similar collateral flow rates, but asymptomatic individuals exhibit more efficient collateral circulation. The severity of ICA stenosis influences the development of collateral pathways.
Area of Science:
- Cerebrovascular disease research
- Medical imaging and diagnostics
- Hemodynamics and blood flow analysis
Background:
- Ischaemic stroke is frequently linked to atherosclerotic lesions in extracranial arteries.
- Assessing the haemodynamic profile of cerebral arteries is crucial for both symptomatic and asymptomatic patients with carotid artery stenosis.
Purpose of the Study:
- To evaluate haemodynamic changes in cerebral arteries among patients diagnosed with significant internal carotid artery (ICA) stenosis.
Main Methods:
- 109 patients were categorized into two groups: asymptomatic ICA stenosis (n=42) and post-stroke (n=67). A control group (n=30) had no significant extracranial artery stenoses.
- Ultrasonographic assessment of flow velocities and directions in cerebral arteries within the circle of Willis and collateral flow was conducted for all participants.
Main Results:
- Asymptomatic patients showed increased flow velocity in the contralateral middle cerebral artery (MCA) and anterior cerebral artery (ACA).
- Patients with ICA stenosis had reduced ipsilateral MCA flow velocity, more pronounced in the post-stroke group.
- Collateral circulation through anterior and posterior communicating arteries (ACoA and PCoA) was equally frequent in both groups, but more efficient in asymptomatic patients.
Conclusions:
- Collateral flow in the circle of Willis is equally prevalent in symptomatic and asymptomatic ICA stenosis patients but functions more effectively in those without symptoms.
- The development rate of collateral circulation is directly dependent on the severity of ICA stenosis.
- The anterior communicating artery (ACoA) plays a key role in maintaining collateral circulation, with the posterior communicating artery (PCoA) also contributing to MCA supply in some cases.
Background:
A significant proportion of ischaemic stroke episodes are caused by atherosclerotic lesions in extracranial arteries. Assessment of haemodynamical profile of cerebral arteries in both symptomatic and asymptomatic patients with carotid artery stenosis is of clinical importance.
Aim:
To assess haemodynamic changes in cerebral arteries in patients with significant internal carotid artery (ICA) stenosis.
Method:
Patients (n=109) were divided into the following groups: group I (GI) - 42 subjects (64.6+/-9.0 years) with asymptomatic ICA stenosis > or =70%; and group II (GII) - 67 subjects (63.4+/-7.1 years) after stroke. The control group consisted of 30 patients (60.3+/-8.9 years) without significant stenoses of extracranial arteries on USG and angiography. In all cases ultrasonographic evaluation of flow velocities and directions in cerebral arteries within the circle of Willis and collateral flow was performed.
Results:
The severity of ICA stenosis did not differ significantly between GI and GII. Patients in GI had flow velocity in the middle cerebral artery (MCA) increased by 15.7% and by 40.8% in the anterior cerebral artery (ACA) contralateral to the ICA stenosis (p<0.001 and p<0.001), whereas in GII no significant changes in flow velocity in these arteries were observed in comparison with the control group. Patients in the groups I and II had lower flow velocities in MCA ipsilateral to the ICA stenosis, however values for GII patients were significantly lower than in GI patients (p<0.001). The presence of collateral circulation through the anterior and posterior communicating arteries (ACoA and PCoA) was similar in GI and GII; however, the flow velocities in the ipsilateral MCA and ACA were significantly higher in asymptomatic patients (GI). The frequency of active collateral circulation through both ACoA and PCoA increased along with the increase of ICA stenosis severity (p=0.003; p<0.001).
Conclusions:
Collateral flow in the circle of Willis in subjects with ICA stenosis occurs equally often in symptomatic and asymptomatic patients; however, it is more efficient in patients without symptoms. The rate of development of collateral circulation depends on ICA stenosis severity. The important role in maintaining collaterals within the circle of Willis is played by ACoA, although in some patients MCA may also be supplied by PCoA.
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