S. Tromp 1, M. Braat 2, J. Van Der Heijden 3, M. Van Egdom 1, P. Dekker 1, M. Haringsma 1, J. Vos 2
1 St Antonius Hospital, Department of Clinical Neurophysiology,
2 St Antonius Hospital, Department of Radiology,
3 St Antonius Hospital, Department of Cardiology – Nieuwegein, Netherlands
Objective: This study was conducted to determine if the use of an emboli protection device prevented distal embolisation in carotid stenting procedures.
Material and Methods: We retrospectively analyzed data of 837 carotid stent procedures between December 1997 and January 2012. Cerebral embolisation was monitored using transcranial Doppler of the ipsilateral middle cerebral artery. Isolated microembolic signals and microembolic showers (cardiac cycles with too many embolisms to count separately) were counted.
Results: 76% of the patients were male. 493 patients were asymptomatic. In >90% of the patients the carotid stenosis was >70%.
A protection device was used in 426 procedures (51%). In the unprotected group a median of 106 isolated embolisms (interquartile range: 69-143) and 16 microembolic showers (4-28) were determined and in the protected group 188 (110-266) and 58 (10-106), respectively (p<0.001).
Separate analysis of the stent deployment and post-dilation phases also showed more embolisation when a filter was used (p<0.001).
To correct for the stent-design, the number of isolated embolisms and showers was compared for each stent-type separately. Four different designs were used: Easy Wall (n=126), Carotid Wall (n=296), Acculink (n=271), and Precise (n=144). For all stent-types a significantly higher number of embolisms and showers were found in the group with the use of a filter, for the total procedure as well as for the phases in which filter placement or removal was not involved.
Discussion: In carotid stent procedures a higher number of microembolic signals were detected with transcranial Doppler of the middle cerebral artery when emboli protection devices were used. This was independent of the stent-type used. Placement and removal of the filters induces embolisms and showers, which might explain our findings. However, even when the embolisms and showers during filter placement and removal were not included, the difference in embolisation remained significant (p<0.001) for the entire population and for the different stent-designs separately.
Key words: carotid artery stenosis, microembolisms, stent, transcranial Doppler.