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Nachrichten, Termine, Experten
Nachrichten, Termine, Experten
MHH neurologist investigates how lipid measurements in the blood can be used to more accurately predict the risk of an impending stroke
In a stroke, the brain is no longer supplied with sufficient blood and oxygen. Around 15 per cent of these ischaemic strokes are caused by narrowing of the carotid arteries. The most common cause of such a narrowing (stenosis) is arteriosclerosis, also known colloquially as hardening of the arteries. Cholesterol, fatty acids and other components from the blood are deposited in the vessel wall and form so-called plaques. This causes the arteries to lose elasticity, narrow and reduce blood flow. There is also the possibility that the plaques are unstable, meaning that individual components become detached and lead to blockages of smaller blood vessels in the brain. There are also people with asymptomatic stenoses who have plaques in their carotid artery but remain clinically inconspicuous. The plaques can be surgically removed with a so-called thrombendarterectomy. Stents - vascular supports made of metal or synthetic fibres - can also be placed over the plaques from the inside and keep the carotid arteries open. Until now, the decision as to whether or not to operate on an asymptomatic stenosis has largely been based on the degree of narrowing.
Particularly in the case of plaques that do not significantly reduce the diameter of the vessel, it is not possible to clearly predict whether they are unstable, i.e. whether plaque components are likely to detach. Dr Ramona Schuppner, a specialist at the Department of Neurology with Clinical Neurophysiology at Hannover Medical School (MHH) and Medical Director of the Stroke Unit and the Neurovascular Ultrasound Laboratory, now wants to find out which stenoses remain inconspicuous and which have an increased risk of a subsequent stroke. With this knowledge, it would be possible to initiate appropriate therapies at an early stage. To this end, the neurologist is focussing on fat metabolism. This is because fats, also known as lipids, play a decisive role in the development of arteriosclerosis. In her latest research project, she is investigating how the blood lipids lipoprotein (a) - Lp(a) for short - and oxidised phospholipids contribute to plaque formation in the carotid arteries and how they influence whether those affected will actually suffer a stroke.
High Lp(a) levels significantly increase the risk
Lp(a) is similar to low density lipoprotein (LDL), also known colloquially as ‘bad’ cholesterol. The level of Lp(a) in the blood is genetically determined. In contrast to high LDL levels, there is currently no authorised medication to treat high Lp(a) levels. Scientific studies have shown that an increased Lp(a) concentration in the blood serum significantly increases the risk of cardiovascular diseases and ischaemic strokes, even when LDL cholesterol levels are very low. A link between Lp(a) and plaques in the aorta has already been found in the past. In addition, Lp(a) is the lipoprotein with the highest proportion of oxidised phospholipids, which is why researchers suspect that these are responsible for a high proportion of the risk. ‘In patients with elevated Lp(a) levels, imaging has already shown evidence of instability with a thin and brittle surface,’ says Dr Schuppner. ‘These plaques rupture more quickly and thus increase the risk of a stroke.’
Composition of plaques significant for stroke risk
In the project, Dr Schuppner, in cooperation with Dr Gerrit Große, a neurologist at the University Hospital Basel (Switzerland), is therefore investigating the extent to which Lp(a) and phospholipids influence the occurrence of stenosis-related stroke. In addition, the neurologists wants to analyse interactions with components of the immune system. ‘If there is a difference between symptomatic and asymptomatic plaques, this could be of significant importance for future treatment decisions,’ Dr Schuppner surmises. If conclusions could be drawn from blood values about the composition of the plaques, it might be possible to make individualised therapy recommendations that take into account both the degree of narrowing and the composition of the plaques.
The project is a collaboration with the MHH Institutes of Pathology, Transplantation Immunology and Clinical Chemistry, the MHH Clinic for Cardiac, Thoracic, Transplantation and Vascular Surgery and the Biochemistry and Infectious Diseases research group at the University of Veterinary Medicine Hannover.The Willi Zimmermann Foundation is supporting the project with 10,000 euros as part of the D-A-CH Lipidology Award.
SERVICE:
For further information, please contact Dr Ramona Schuppner, schuppner.ramona@mh-hannover.de.
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