Year: 2019
Type: dissertation
Abstract: Transcatheter aortic valve implantation (TAVI) is a recent development in the treatment of severe aortic stenosis, whereby a new valve is inserted without the need for open heart surgery. It has been associated with a high stroke risk in early studies and the risk is thought to be primarily embolic. I used Transcranial Doppler (TCD) to assess the effects of embolization on the brain. Initially a pilot study was performed with TCD to establish a suitable protocol, prior to moving to a full study of TCD. This showed embolization was present in all TAVI procedures at each stage, but most frequent during valve deployment. The same TCD protocol along with MRI scans was used in a multi-centre study called DEFLECT-1, looking at a novel embolic deflection device named the TriGuard device. This showed cerebral infarct volume, but not embolic number, was reduced using the device compared with historical controls. I also used the data collected from TCD in a study showing that balloon aortic valvuloplasty (BAV) was an unnecessary part of the TAVI procedure when using balloon-expandable valves. Highly calcified valve tissue is displaced during the TAVI procedure, a likely embolic source. I assessed aortic valve calcification from CT scans and showed that the degree of calcification correlated with the number of emboli released during valve deployment. Finally I looked at the effects of TAVI on cognitive function. The rationale for a new battery of cognitive tests using a fully computerised system of cognitive testing (CANTAB Eclipse) is given. This battery of tests was then used to assess cognitive function pre-TAVI and post-TAVI at various time intervals. I showed that there was improvement in certain domains and overall there was no evidence of declining cognition in any domain.
Author: Suneil Aggarwal
Language: English
Subfield: Cardiology and Cardiovascular Medicine
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W2996291949