Transcranial Doppler sound detection of cerebral microembolism during transapical aortic valve implantation

Transapical aortic valve implantation (TAVI) is a new method that might reduce the surgical risk of conventional surgical aortic valve replacement in very high-risk patients. Increased downstream microembolization is expected in transapical aortic valve implantation. However, whether it usually occurs, how often, and its clinical relevance are not known. We report the results of ultrasound microembolic signal detection in the middle cerebral artery during the procedure.

Fifty patients (mean age: 80 ± 5 years; mean EuroSCORE: 36 ± 13 %) underwent transapical aortic valve implantation. Intraoperative transcranial Doppler (TCD) sound examination of both middle cerebral arteries (MCA) was used to identify high-intensity transient signals (HITS) and microembolic signals (MES) during seven phases of the procedure. Pre- and postoperative computed tomography of the brain and clinical neurological examinations were performed preoperatively and daily during the first postoperative week.

During the procedure, HITS [right MCA: 435 ± 922 (range 9-5765); left MCA: 471 ± 996 (range 24-6432)] and MES [right MCA: 78 ± 172 (range 1-955); left MCA: 62 ± 190 (range 2-1553)] were detected in all patients. Most of the MES were recorded during valvuloplasty [right MCA: 3 ± 5.6 (range 0-31); left MCA: 2 ± 4.9 (range 0-30)] and positioning of the prosthetic valve in the aortic position [right MCA: 6 ± 5 (range 0-22); left MCA: 2 ± 6.9 (range 0-38)]. Postoperatively, there were no clinical signs of new cerebral embolism.

Cerebral microemboli were detected by intraoperative transcranial Doppler sound examinations in all patients during transapical aortic valve implantation. Most of the signals were detected during balloon valvuloplasty and delivery of the prosthetic valve.