What is Carotid Endarterectomy?
Carotid Endarterectomy (CEA) is a surgical procedure designed to remove plaque in the Carotid artery by separating it from the carotid arterial wall. Thus, carotid arterial constriction, which may cause a decrease in cerebral perfusion as well as a potential source for cerebral emboli, is removed.
How to use TCD for Endarterectomy
Cerebral blood flow monitoring during Carotid Endarterectomy is one of the most frequently used applications of TCD monitoring. The primary goal of TCD monitoring is to ensure that cerebral perfusion is not severely or irreversibly impaired during the CEA procedure and particularly during the intraoperative clamping of the carotid artery.
The second goal of utmost importance is to monitor the release of emboli into the cerebral circulation during the CEA operation, and particularly during dissection and during clamp release.
The primary purpose of TCD monitoring during CEA is to minimize the risks to the brain and modify the clinical intervention in real-time during CEA. For example, detection of cerebral ischemia during cross-clamping suggests the need to insert a shunt in order to protect the brain. TCD also presents critical information if the collateral circulation provides protection to the brain during the operation and also the important assessment of the autoregulatory capacity of the circulation during the different stages of the intervention.
Using Dolphin for Endarterectomy
The Dolphin provides a range of intraoperative monitoring means that allow cerebral monitoring during CEA. In addition to the standard bilateral monitoring headset, the Dolphin systems support the bilateral Dolphin/XF TCD Robot, which automatically identifies intracranial blood flow and assists the physicians in the monitoring process.
The Monitoring options of the Dolphin TCD device include a clear bilateral trend display of the critical parameters of interest, which may include the peak and mean blood flow velocities and the pulsatility index (PI) or the resistance index (RI). Thus, determination of cerebral perfusion during critical stages of the surgery are immediately presented and allow timely intervention.
In addition, all suspected embolic events during the operation are automatically counted and displayed on the screen with the Dolphin’s unique high resolution HITS detection capabilities.
These capabilities allow viewing embolic showers with great resolution, which may occur when the clamp is removed. A Power M Mode display further supports the identification of embolic events.
Expected Results
The primary goal of TCD monitoring is to ensure that cerebral ischemia and associated strokes are prevented.
There are various different criteria in the literature to ensure that MCA velocity maintains enough flow during all stages. In some cases, it has been shown that an MCA velocity higher than 10 cm/sec during the critical carotid clamping suggests adequate collateral circulation. On the other hand, intra- and post-operative strokes are associated with a severe (>90%) reduction in velocity with clamping or doubling of the PI (>100%) during the release of clamping.
In addition, post-operative stroke is highly correlated with the amount of TCD detected emboli during CEA.
Selected Literature
Role of transcranial Doppler ultrasonography in stroke, Sanjukta Sarkar et al., Postgrad Med J 2007;83:683–689
Cerebral monitoring during carotid endarterectomy by transcranial Doppler ultrasonography, Woo-Sung Yun, Ann Surg Treat Res 2017;92(2):105-109
Transcranial Doppler ultrasonography in anaesthesia and intensive care, I. K. Moppett and R. P. Mahajan, British Journal of Anaesthesia 93 (5): 710–24 (2004)
Assessment: transcranial Doppler ultrasonography: Report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology. Sloan MA et al., Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology. Neurology. 2004 May 11;62(9):1468-81
Transcranial Doppler Monitoring and Causes of Stroke From Carotid Endarterectomy, Merrill P. Spencer, Stroke, Volume 28, Issue 4, April 1997, Pages 685-691
Ultrasound Assessment of the Intracranial Arteries, Nabavi, Ritter, Otis, and Ringelstein, Introduction to Vascular Ultrasonography, By John Pellerito, MD and Joseph F Polak, 2012
Neuro-ultrasonography, Ryan Hakimi, Andrei V. Alexandrov, and Zsolt Garami, Neurol Clin 38 (2020) 215–229
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