Intraoperative duplex scanning after carotid artery reconstruction: a valuable tool

The operative management of extracranial cerebrovascular occlusive disease requires meticulous surgical technique. Intraoperative duplex imaging (10 MHz B-mode ultrasound combined with 7.5 MHz Doppler spectrum analysis) was used in an attempt to recognize technical problems that might result in serious neurologic injury. Eighty-four carotid arteries were studied in 76 consecutive patients undergoing carotid endarterectomy or reconstruction. Indications for operation included carotid territory transient ischemic attack (n = 36 [43%]), amaurosis fugax (n = 16 [19%]), stroke (n = 11 [13%]), asymptomatic stenosis (n = 11 [13%]), vertebrobasilar transient ischemic attack (n = 7 [8%]), recurrent stenosis (n = 2 [2%]), and trauma (n = 1 [1%]). Arterial anatomy was assessed ultrasonographically and duplex-derived velocity measurements were obtained to assess hemodynamics. Increased velocity measurement was noted to correlate with ultrasound image of stenosis. Technical errors were identified in 17 patients (22%), including six persons with residual internal carotid artery stenoses, three persons with hemodynamically significant stenoses caused by "kinked" internal carotid arteries, eight persons with debris or intimal flaps in their external carotid arteries, and one person with an occluded external carotid artery. The intraoperative duplex scan led to corrective measures during the surgical procedure in eight patients (11%). No new ipsilateral brain injury was noted in the 76 patients postoperatively. Intraoperative duplex scanning accurately identified residual stenosis, intraluminal thrombus, and loose debris. Duplex scanning altered intraoperative decision making in a significant proportion of patients studied.