Changes in middle cerebral artery pulsatility during the first days after carotid endarterectomy.

During carotid endarterectomy a significant stenosis is removed from the lumen
of the internal carotid artery. This will allow a better conduction of blood
volume and of the blood pressure wave over the carotid arteries. Most patients
have little problem with this increase in perfusion pressure. In some, however,
the perfusion pressure cannot sufficiently be overcome by vascular resistance
and the blood pressure wave may travel into the cerebral capillaries at risk of
causing cerebral oedema, haemorrhage, swelling and, ultimately, death. This is
called a hyperperfusion syndrome.
Customary, all patients who receive carotid endarterectomy at the Martini
Ziekenhuis Groningen are monitored by dailyTCD examination for the early
detection of an imminent hyperperfusion syndrome. The present investigation
wishes to expand this protocol by a simultaneous recording of the
electrocardiogram, of the carbon dioxide content of exhalation gas and of the
blood pressure. These extra signals allow the calculation of a so-called
PaR-value, which gives better information on intracranial hemodynamics than TCD
alone.

To gain understanding about the changes in intracranial hemodynamics after
carotid endarterectomy. To improve the early detection of an imminent
hyperperfusion syndrome.

Instead of the usual follow up with a TCD examination on day 0 preoperatively
and on day 0-3 postoperatively, the study is designed to record simultaneously
with the TCD signal the electrocardiogram, the end-tidal carbond dioxide and
the arterial blood pressure. All signals are recorded non-invasively.
Combining the TCD signal with the ABP signal will allow the calculation of the
so-called pulsatile apparent resistance or PaR, a parameter that has been shown
to give better information on intracranial hemodynamics than TCD alone.

Instead of 5 times a TCD examination during the first 3 postoperative days
after carotid endarterectomy the subjects will undergo 5 times a PaR
measurement during the first 3 postoperative days. The usual TCD examination
takes about 30 minutes, whereas the PaR measurement takes roughly 60 minutes
(30 min. preparation; 30 min. actual measurement).