Aortic valve stenosis is the
most frequent heart valve defect of older people in Europe – the cause is
usually increasing calcification of this important valve. In patients at high
and excessive risk, conventional cardiac surgery is often no therapeutic
option. For these patients, transcatheter aortic valve implantation (TAVI)
remains the only opportunity. However, this procedure often leads to a
crumbling and spreading of valvular calcium deposits and consecutive occlusion
of smallest blood vessels of the brain. Conceivably, this so called
“microembolisation”, could thus lead to impairment of mental performance. In a
long-term study, cardiologists at the Heart Center of the Bonn University
Medical Center, under the leadership of Prof. Georg Nickenig were able to
exclude significant cognitive impairment for the majority of patients
undergoing TAVI.
“Even the technologically
mature intervention of TAVI is associated with some risks” Prof. Nickenig
knows. Small particles of valvular calcium deposits can be mobilized during the
procedure and spread to the brain in the bloodstream. Hence, interventional and
surgical replacement of severely calcified heart valves are associated with a
stroke risk of approximately 2-5%. In contrast, the cognitive performance
level, such as intellectual function, memory, orientation, and concentration of
the patients, had not yet been studied over the long term following
implantation of an aortic valve. “However, this is of great importance in the
ability of elderly patients to cope with everyday life and to retain their
independence, in particular considering the rising life expectancy”; said Dr
Alexander Ghanem, Senior Physician at the Department of Medicine of the Bonn
University Medical Center.
With this in mind, Dr
Ghanem, in cooperation with the Department of Radiology of the Bonn University
Medical Center, prospectively investigated 125 high-risk patients using MRI
exams of the brain following aortic valve implantation. The results have recently
been published (Ghanem A et al. Cognitive trajectory after transcatheter aortic valve
implantation. Circ Cardiovasc Interv. 2013; 6: 615). Microembolisms were frequently observed in the
patients’ brains – as a result of calcium deposits from the heart valve that
spread into the brain. The question arises whether such clinically silent
“microembolism” could be associated with the later occurrence of dementia
spectrum disorders. Thus, Ghanem tested and compared the cognitive capacity and
memory capacity of patients before and after the intervention: “ More than 90
percent remained consistently unharmed over two years after valve
implantation”. However elderly patients with aortic valve stenosis often have
restricted cognitive capacity prior to TAVI – possibly due to a narrowed aortic
valve, leading, among other things, to inadequate blood supply in the brain.
“Happily, even patients with markedly below average cognitive performance prior
to the intervention had no significant decay of cognitive and mental
performance levels for up to two years after the intervention.