PHILADELPHIA — Strokes and technical failures following carotid artery stenting are often caused by preventable errors, according to an analysis of 207 procedures in high-risk patients at one center.
Based on an analysis of six strokes and four technical failures that occurred in these 207 patients, vascular surgeons at Washington University, St. Louis, have changed their carotid artery stenting protocols to avoid these errors in the future, Dr. Ravi K. Veeraswamy said at a session of the Peripheral Vascular Surgery Society during the Vascular Annual Meeting.
To eliminate the errors, Washington University surgeons now use early anticoagulation before any catheter manipulation; they also limit catheter manipulation within the aortic arch, obtain a right anterior oblique view of the carotid artery and associated vessels, and match the embolic protection device and stent that they use to the patient's vascular anatomy and lesion, said Dr. Veeraswamy, a vascular surgeon at the university.
One stroke in the series was associated with inadequate anticoagulation. Systemic heparin treatment had not been started before the femoral sheath was displaced, which led to embolization within the catheter.
Two other strokes appeared to be caused by excessive manipulation of catheters within aortic arches that had severe atherosclerotic disease. As a result of these errors, the group began to apply the “3-30” rule: They now do not use more than three catheters or try for more than 30 minutes to cannulate the carotid artery.
A fourth stroke was attributed to inadequate imaging of the carotid artery and associated vessels. In this case, the surgeons relied entirely on a left anterior oblique view, but this did not provide enough anatomic information. The surgeons now routinely get a right anterior oblique image, which gives them important, additional information.
The fifth stroke was linked to stent selection. There is increasing awareness that open-cell stents can allow soft plaque to extrude through the stent struts and potentially cause embolization. Although open-cell stents have better mobility and are easier to use in vessels with difficult anatomy, the threat of embolization is a major drawback. In the case evaluated, the patient received an open-cell stent and within 2 hours began to show neurologic complications. Imaging showed that small particles were pushed through the stent cells. The surgeons placed a second, closed-cell stent inside of the open-cell stent, and the neurologic symptoms resolved.
The sixth stroke case involved an embolic protection device that was not suited to work in a long and irregular lesion that had a difficult anatomy. A better approach in such patients is flow reversal to remove emboli. In the current series of 207 patients, flow reversal was used in 27% of patients, a higher rate than in other reported series, Dr. Veeraswamy said.
The four technical failures included a conversion to carotid endarterectomy after the carotid artery was dissected by an advancing sheath. A second conversion to open surgery was done because circumferential arterial calcification caused persistent, severe stenosis. Two other patients had their stenting aborted when it became apparent that their lesions could not be safely crossed with a stent.