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Thesis topic proposal
 
Péter Légrády
Investigation of subclinical target organ damages and cardiac autonomic function in hypertensive and normotensive individuals

THESIS TOPIC PROPOSAL

Institute: University of Szeged
theoretical medicine
Graduate School of Multidisciplinar Medical Scienses

Thesis supervisor: Péter Légrády
co-supervisor: György Ábrahám
Location of studies: 1st Depatment of Internal Medicine, Faculty of Medicine, University of Szeged, H-6720 Szeged, Korányi fasor 8-10.Hungary
Abbreviation of location of studies: ÁOK


Description of the research topic:

The sympathetic nerve system has an important role in the pathogenesis not only of
hypertension (HT) and diabetes mellitus, but also of the metabolic syndrome, congestive heart
failure, and renal insufficiency. The pathogenesis of HT is of highly sophisticated complexity,
but increased sympathetic nerve activity plays a major role. Stress also plays a role in the
activation of SNA. Sublcinical target organ damages of HT are such abnormal parameters that
are without any clinical symptoms, like increased pulse wave velocity (PWV >12 m/s),
decreased ankle-brachial index (ABI ≤0.9), mild elevation of serum kreatinin level (men 115-
133 μmol/l, women 107-124 μmol/l), decrease of estimated glomerular filtration rate (eGFR
<60 ml/min/1.73m2).
The CAN may cause symptoms ranging from resting tachycardia to sudden cardiac death. The
early parasympathetic damage may lead to a relative sympathetic overactivity with the
development of an increased heart rate (HR) before HT has appeared. The baroreflex is one of
the most important mechanisms for preventing excessive changes in BP. The baroreflex
sensitivity (BRS) is an index of the sensitivity of arterial baroreflex modulation of HR.
Decreased BRS indirectly is a maker of rised sympathetic nerve activity.
Aims: To investigate CAN in HT patients and normotensives. To look for any association
between the duration of HT, BP values and CAN; between subclinical target organ damages
of HT and CAN; antihypertensive therapeutic efforts and CAN and subclinical target organ
damages.
Methods: An oral glucose tolerance test will be performed in all non-diabetic individuals in
order to exclude diabetes mellitus and impaired glucose tolerance. The CAN will be assessed
by means of the five standard cardiovascular reflex tests proposed by Ewing. The
parasympathetic function was characterized via the changes in HR in response to deep
breathing, to the Valsalva manoeuvre, and to standing up (30/15 ratio). The sympathetic
function was characterized via the systolic BP changes in response to standing up and via the
diastolic BP changes in response to a sustained handgrip. In all tests, normal values will be
scored 0, borderline values 1, and abnormal values 2. The sum of the scores gives the total
CAN score. A patient will be considered as CAN-positive if the score is 2 or higher (at least 2
tests with borderline or 1 test with abnormal values). Spontaneous BRS will be calculated in
10 minutes lying and 10 minutes standing positions via a sequence (time-domain) method
using a software package for BRS analysis (Nevrokard BRS 5.1.3; Medistar). Data necessary
for calculation will generated via a beat-to-beat data acquisition system by finger
photoplethysmography (Finometer, TPD Biomedical Instruments) at 200 Hz combined with
an ECG. The carotid-femoral and carotid-radial PWV will be measured with PulsPen device
(DiaTecne s.r.l.). ABI will be estimated with Nicolet Vascular Elite 200 (Natus Medical Inc.)
device.

Required language skills: English
Recommended language skills: English
Further requirements: 
TDK munka

Number of students who can be accepted: 1

Deadline for application: 2017-03-15

 
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