Reduced frequency of embolic signals in severe carotid stenosis with poststenotic flow velocity reduction
Michael Goertler1, Till Blaser, Susanne Guhr
1Department of Neurology, University of Magdeburg, Magdeburg, Germany. michael.goertler@medizin.uni-magdeburg.de
Insights
Low blood flow behind severe carotid stenosis reduces artery-to-artery embolism. This finding suggests reduced blood flow across carotid stenosis leads to fewer embolic signals in symptomatic patients.
Area of Science:
- Neurology
- Vascular Medicine
- Medical Imaging
Background:
- Investigating the impact of post-stenotic low blood flow in patients with recent symptomatic severe carotid stenosis.
- Examining the relationship between blood flow dynamics and arterio-arterial embolism.
Purpose of the Study:
- To determine if reduced post-stenotic blood flow affects the occurrence of embolic signals in patients with severe carotid stenosis.
- To analyze the association between post-stenotic flow velocity and embolic events.
Main Methods:
- Analysis of 206 patients with recent ischemic events and ipsilateral carotid artery stenosis (>30% diameter reduction).
- Utilized Doppler/duplex sonography to measure post-stenotic flow velocity.
- Conducted 1-hour transcranial Doppler monitoring to detect embolic signals.
Main Results:
- Reduced post-stenotic flow velocity (<20 cm/s systolic) was observed in 17 out of 37 patients with very severe stenosis.
- Embolic signal probability increased with stenosis severity, peaking at >90% diameter reduction without reduced flow.
- Low post-stenotic flow velocity significantly decreased embolic signal frequency (aOR 0.15; P=0.038) in very severe stenosis.
Conclusions:
- Low post-stenotic flow velocity in severe internal carotid stenosis reduces embolic signals in symptomatic patients.
- This supports the hypothesis that reduced blood flow across carotid stenosis mitigates embolism.
Background:
We aimed to investigate the effect of poststenotic low blood flow in patients with recently symptomatic severe carotid stenosis on arterio-arterial embolism.
Methods:
Analyses based on a series of 206 consecutive patients (155 men and 51 women, mean age 65.3 years) with a nondisabling ischemic event in the anterior circulation < or =30 days (median 4.5) before presentation and diagnosis of ipsilateral carotid artery stenosis/occlusion (> or =30% local diameter reduction). All patients underwent Doppler/duplex sonography, which included measurement of poststenotic flow velocity as an indicator for poststenotic blood flow as well as a 1-hour transcranial Doppler monitoring for the detection of embolic signals.
Results:
Thirty-seven of two hundred and six patients had very severe stenosis which was associated with reduced poststenotic flow velocity (<20 cm/s systolic) in 17 patients. Probability of embolic signals increased with increasing degree of stenosis and was maximal in patients with stenoses > or =90% local diameter reduction if poststenotic flow velocity was not reduced. Reduced poststenotic flow velocity in patients with very severe stenosis was associated with a significantly lower frequency of embolic signals compared to patients with the same degree of stenosis but no velocity reduction (adjusted odds ratio 0.15, 95% confidence interval 0.025-0.897, p = 0.038, adjustment for antiplatelet medication and time since ischemia).
Conclusions:
Low poststenotic flow velocity behind very severe internal carotid stenosis reduces the otherwise high frequency of embolic signals in recently symptomatic patients corroborating the hypothesis that reduced blood flow across carotid stenosis causes reduced embolism.