Carotid artery dynamics during head movements: a reason for concern with regard to carotid stenting?
A W Floris Vos1, Matteus A M Linsen, J Tim Marcus
1Department of Surgery, Vrije Universiteit Medical Center, Amsterdam, The Netherlands.
Insights
Carotid stenting limits artery flexibility, causing sharp angulation, especially when bending the head forward. Current stent designs do not accommodate the significant torsion shear experienced by the common and internal carotid arteries during head turns.
Area of Science:
- Vascular Surgery
- Medical Imaging
- Biomechanics
Background:
- Carotid angioplasty/stenting (CAS) is a common procedure for treating carotid artery stenosis.
- Understanding the biomechanical effects of CAS on carotid artery mobility is crucial for patient outcomes.
Purpose of the Study:
- To evaluate carotid artery mobility patterns during various head movements after CAS.
- To assess the impact of head movements on angulation and torsion shear in stented and unstented carotid arteries.
Main Methods:
- 3D time-of-flight magnetic resonance angiography was used in 7 male patients post-CAS.
- Carotid artery mobility was assessed in 5 head positions (neutral, left/right turn, forward/backward bend).
- Angulation at stent junctions and torsion shear in the common carotid artery (CCA) and internal carotid artery (ICA) were measured.
Main Results:
- Significant angulation occurred at the distal stent junction, particularly with forward head bending (p=0.028).
- Stented carotid sections showed no flexibility, while unstented sections exhibited diffuse changes.
- Considerable torsion shear was observed in the CCA and ICA during lateral head movements.
Conclusions:
- CAS leads to sharp internal carotid artery angulation aggravated by forward head bending.
- Stented carotid segments lack flexibility, contrasting with the ex vivo flexibility of the stents themselves.
- Existing stent designs do not adequately accommodate the torsion shear experienced by the carotid arteries during head rotation.
Purpose:
To evaluate carotid artery mobility patterns during head movements following carotid angioplasty/stenting (CAS).
Methods:
In 7 patients (all men; mean age 69 years, range 65-76) who had undergone unilateral CAS, 3D time-of-flight magnetic resonance angiography was performed, visualizing both carotid arteries in 5 different head positions (neutral, turned left and right, and bent forward and backward). Maximum intensity projection reconstructions were obtained to measure angulation at the proximal and distal stent junction. Configuration changes of the stented section of the carotid artery and the unstented contralateral artery were judged. Secondly, transverse sections at the level of the carotid bifurcation and at the skull base were used to calculate torsion shear in the common and internal carotid arteries (CCA, ICA) during left and right head position. Results were expressed as median (range).
Results:
In neutral head position, maximal angulation at the distal stent junction was 34.3 degrees (32.3 degrees-55.6 degrees). With the head bent forward, this angulation changed to 47.6 degrees (42.6 degrees-85.2 degrees, p=0.028) and when bent backward to 26.5 degrees (25.0 degrees-48.7 degrees, p=0.027). In all patients, configuration changes of the stented sections were absent. The contralateral unstented side showed diffuse configuration changes without specific angulation at one location. With the head turned left and right, the CCA on the stented side was subjected to 28.6 degrees (13.6 degrees-53.7 degrees) and 24.9 degrees (2.0 degrees-50.6 degrees) of torsion shear, respectively. Torsion of the ICA was subsequently 18.1 degrees (12.7 degrees-40.5 degrees) and 15.2 degrees (2.9 degrees-69.4 degrees).
Conclusions:
Following carotid stenting, sharp ICA angulation that are aggravated by forward bending of the head occur at the distal stent junction. The stented section of the carotid artery shows complete lack of flexibility despite highly flexible features of hte stents ex vivo. Both the CCA and ICA are subjected to considerable torsion shear with the head turned left and right. This shear is not accommodated by the current stent designs.
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