Transcranial Doppler-detected cerebral embolic load during transcatheter aortic valve implantation

Transcatheter aortic valve implantation (TAVI) is an alternative to surgery for high-risk patients with severe aortic valve stenosis. Periprocedural stroke is reported at an incidence up to 10%. Magnetic resonance imaging studies have identified new onset of clinically silent ischaemic cerebral lesions more frequently (68-84%). So far, few data are available about cerebral embolism during TAVI. The aim of this study was to determine the frequency of high-intensity transient signals (HITS) and to explore differences in the HITS pattern between transfemoral and transapical access and between self-expanding (SE) and balloon-expandable (BE) deployment technique.

Transcranial Doppler (TCD) ultrasound recordings of 44 patients undergoing TAVI (age 78 ± 6 years; logistic EuroSCORE 28 ± 15%; transfemoral access, n = 32; transapical access, n = 12; SE, n = 27; BE, n = 17) were analysed for HITS during the following intervals: (i) instrumentation prior to valvuloplasty, (ii) balloon valvuloplasty, (iii) prosthesis deployment (DP) and (iv) post-implantation (PI) including any re-dilatation episodes. The total procedural load of HITS and HITS frequency in procedural intervals were compared between different access routes and DP techniques. Periprocedural neurocognitive impairment was assessed clinically and by the confusion assessment method (CAM) prior to TAVI and on post-procedural days 1 and 4-6.

TCD recordings demonstrated the occurrence of HITS in all patients. DP was associated with the highest load of HITS. Access route did not significantly influence the total burden of periprocedural HITS. During procedures using the SE type, a slightly larger total load of HITS was observed than with the BE type (P = 0.024). This was mainly due to more HITS during the DP (P = 0.027) and the PI interval (P = 0.002). No incidence of delirium was detected by CAM ratings. Two patients suffered a new onset of stroke within the 2 weeks following the procedure. In-hospital death and 30-day mortality were 0/44.

HITS are observed during all procedural intervals in TAVI. The embolic events appear to peak during DP. In our series, the overall cerebral embolic load did not differ between the transfemoral and the transapical access route. TCD monitoring in TAVI is useful to identify periods and manipulations associated with an increased cerebral embolic load and may help to further enhance the safety of this procedure.