NEW YORK — A critical look at the procedure of carotid angioplasty and stenting indicates that there are still unavoidable complications associated with it. Both embolization and hypotension during the procedure have been linked to neurologic injury.
Although carotid angioplasty and stenting (CAS) has emerged as a treatment alternative for carotid artery stenosis, the current standard is still the surgical removal of plaque with carotid endarterectomy (CEA). Stroke after CAS is assumed to be embolic. “Neurologic deficit remains the most feared of all procedure-related complications,” said Dr. Peter H. Lin at the Veith symposium on vascular medicine sponsored by Montefiore Medical Center.
“Disruption of atherosclerotic plaque is a disadvantage with carotid stenting. There are eight times more embolizations seen with CAS than with CEA,” said Dr. Lin of Baylor College of Medicine, Houston.
Dr. Lin and colleagues conducted a study demonstrating the significance of carotid plaque echomorphology in assessing the embolization risk during CAS. Results from a total of 234 CAS procedures performed in 213 patients with a mean stenosis of 85% showed that the incidence of embolization was increased with hypoechoic plaque and that neuroprotective devices should be used.
At the session, Dr. Klaus D. Mathias, of the department of radiology at Klinikum Dortmund (Germany), agreed that embolic injury to the brain is the main problem associated with carotid stenting procedures. “Any phase of stenting can produce emboli. There is 3–5 times more embolic material released to the brain with unprotected carotid stenting than with surgery,” he said.
According to Dr. Mathias, filter protection is the preferred embolic protective device. A 60% reduction in complications from 3.5% to 1.5% has been reported in previous studies, looking at the outcome of procedure-related complications using neuroprotective filters. “The German PROCAS registry showed a 30%–60% reduction in neurologic events with protective filters, but we are still missing prospective trials,” said Dr. Mathias.
Another feared periprocedural complication leading to neurologic injury that has not received enough attention by clinicians and industry, according to some physicians, is hypotension. “Hemodynamic changes are common events during CAS and CEA, occurring in up to 30% of patients,” said Marc van Sambeek, Ph.D., head of the section of vascular surgery at University Hospital, Rotterdam (the Netherlands).
Hypotension, if sufficiently severe, may cause watershed infarction. Lesser degrees of hypotension may render an otherwise inconsequential microembolic shower very relevant owing to impaired washout, and also lead to a reduction in adequate collateral blood flow to an ischemic territory in the brain.
Although hemodynamic instability is well recognized in patients after CEA, where postoperative hypertension has been known to be associated with stroke or death, studies suggest that CEA has been associated with hypotension.
CAS is currently being investigated as a promising alternative, but despite favorable results from initial series, hemodynamic instability may complicate this procedure, said Dr. Sambeek.
“Cerebral autoregulation normally protects the brain from changes in perfusion pressure. In some patients this autoregulation is exhausted by ischemia,” Dr. Sambeek explained. Hemodynamic changes during CAS can be caused by two mechanisms. Hemodynamic instability can be caused due to the triggering of baroreceptors of the carotid sinus, as well as the release of catecholamines. “Hemodynamic instability is greater during CAS than in CEA,” said Dr. Sambeek.
In a study presented at the meeting, Dr. Sambeek and colleagues evaluated the patterns of adrenaline and noradrenaline release in CAS and CEA. They found that patterns of catecholamine release were significantly different in patients undergoing CAS and CEA with much higher, more variable surges occurring in CEA patients.
Assessment of clinical results of a series of 121 patients by Dr. Sambeek and colleagues, showed the occurrence of two major strokes and five minor strokes. The majority of complications were related to hemodynamic instability.
“At the current time, CAS should be performed with cerebral protection using filter devices. In addition to embolic risks associated with the procedure, these authors have alluded to the significance of periprocedural hemodynamic instability,” said Dr. Ron Fairman, chief of the division of vascular surgery at the Hospital of the University of Pennsylvania, Philadelphia.
“In our own series, we have experienced occasional hypotension requiring continuous pharmacologic support for 24–36 hours following CAS. Other troubling phenomenon include troponin ‘leaks’ in association with hypotension, as well as symptoms of cerebral reperfusion which seem to occur with greater frequency than following CEA. Physicians should anticipate these events and be prepared to intervene in order to prevent cardiac and cerebral compromise” he concluded.
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