Reconstruction of the right common carotid artery has been shown to be feasible in neonates after extracorporeal membrane oxygenation (ECMO). However, the long-term outcome after carotid artery reconstruction (CAR) remains unknown. The purpose of this study was to evaluate the natural progression of the anastomotic site after CAR. Between February 1990 and June 1993, 201 patients received ECMO. All veno-arterial (VA) ECMO patients (n = 172) were considered candidates for reconstruction unless a significant neurological event tie, intracranial hemorrhage, stroke) had occurred; the duration of ECMO exceeded 10 days, making carotid mobilization difficult; or the patient's prognosis was deemed poor. Reconstruction was performed by excising the arteriotomy site, followed by primary end-to end anastomosis. Reconstruction was abandoned and the artery ligated if an intimal flap, arterial thrombosis, or excessive tension was encountered. After reconstruction all patients had early carotid ultrasonography and either head computed tomography (CT) or magnetic resonance imaging (MRI). Subsequent ultrasound examinations were Performed at approximately 6 month intervals. Diameter index (DI) (a measure of anastomotic narrowing) was calculated using ultrasound by dividing the anastomotic diameter by the diameter of the carotid artery 5 mm proximal to the anastomosis. Forty-three of 172 VA ECMO patients (25%) had successful reconstruction. Long term follow-up data were available on 27 patients. These 27 patients had 39 ultrasound examinations, with an average fellow-up time of 7.3 months (range, 4 days to 29 months). All carotid arteries were patent. Linear regression analysis showed significant improvement in the Di with time (P = .0001, r(2) = .382). Patients were grouped according to follow-up interval: group I (0 to 6 months), 21 ultrasounds; group II (>6 months), 18 ultrasounds. A statistically significant increase in DI was found between groups I and II (P = .0001). Eight patients who had follow-up ultrasound examinations performed during both intervals described by groups I and II also showed significant increase in DI (P = .0001). The final head ultrasound findings before decannulation were normal in all but one case. Five of 43 patients (12%) subsequently had an abnormal head CT or MRI result after CAR, none of which lateralized to the side of reconstruction. From these preliminary data the authors conclude that (1) CAR is feasible; (2) A high patency rate exists after reconstruction; (3) Early anastomotic narrowing is common, but improves with time; (4) CAR does not appear to induce ipsilateral brain injury. However, neurodevelopmental studies will be necessary to determine whether there is any long-term benefit from CAR. Copyright (C) 1995 by W.B. Saunders Company