The goal of this clinical trial is to define and compare pre-load dependance of thecardiac function according to the intracardiac hydrostatic gradient of pressure inhealthy and diabetic populations.Participants will undergo 4 tilt angle and 4 lower body negative pressure intensitiesduring which cardiovascular data will be assessed and a transthoracic echography will beperformed.
Gravitational force affects both the cardiac mass and the thoracic compartment. However,
few studies in humans have explored whether the relationship between cardiac function and
load-dependence varies according to the orientation of the heart in space (e.g. between
the upright and supine positions) and therefore according to gravitational stress.
Thirty-two volunteers (16 healthy subjects and 16 subjects with type I diabetes) will be
included in the study. Each subject will be analysed over half a day in the Inserm COMETE
laboratory. Measurements of the intra-cardiac hydrostatic pressure gradient (reflecting
gravitational force) and indicators of cardiac function will be analysed by transthoracic
echocardiography using dedicated post-processing software. These measurements will be
compared at identical pre-load on the basis of the relationship between thoracic
impedance and angle of vertical inclination using a Tilt Test on the one hand and between
thoracic impedance and Lower Body Negative Pressure (LBNP) depression in the supine
position on the other. In the supine position, the echocardiogram will be repeated for
each subject with different levels of intensity of preload decrease by LBNP up to a
maximum of -50 torr, and compared with different angles of vertical inclination head up
up to +80° on the Tilt Test.
The study aims to compare the contribution of intra-cardiac hydrostatic force to cardiac
filling and ejection mechanics in a population of healthy volunteers and subjects with
diabetes.
The goal is to define and compare the pre-load dependence of the cardiac function indices
studied according to the anatomical supine posture with zero intra-cardiac hydrostatic
gradient with the standing posture during which the hydrostatic force is expressed
between the cardiac base and apex. The hypothesis is that cardiac filling and ejection
are improved when the longitudinal axis of the heart is anatomically oriented in the
standing position compared with the supine position, by restoring the intraventricular
hydrostatic pressure gradient. Comparing a group of healthy subjects with a group of
subjects with diabetes will enable to assess whether the dependence of cardiac function
on the orientation of the heart in space is more marked in the presence of subclinical
impairment of myocardial function.
Other: Cardiovascular and Baroreflex stimulation by Tilting
Tilt of the patient at 4 angles (22°, 42°, 58° and 80°), the order is randomized for 3
angles (22°, 42°, 58°) while 80° will always be last.
Other Name: Tilt
Other: Cardiovascular and Baroreflex stimulation by Lower Body Negative Pressure
The patient will undergo 4 level of LBNP (10Torr, 20Torr, 35Torr, 50Torr), the order is
randomized for 3 intensities (10Torr, 20Torr, 35Torr) while 50Torr will always be last.
Other Name: LBNP
Inclusion Criteria:
- Affiliated to the social security system
- Patient informed of the study and having signed an informed consent form
- Type 1 diabetes for at least 10 years followed at Caen University Hospital, equipped
with a continous glucose monitoring system
Exclusion Criteria:
- Trained athletes (≥ 6 hours of sustained physical exercise >70% VO2max per week for
> 6 months)
- Chronic cardiovascular disease or cardiovascular treatment
- Personal history of chemotherapy and/or thoracic radiotherapy
- Cerebral and/or spinal disease
- Inclusion of the subject in another biomedical research protocol of interventional
type (during the study or in the 3 months prior to inclusion)
- Pregnant, breast-feeding or parturient women
- Adults under legal protection (guardianship, curators) or unable to express their
consent or deprived of their freedom
Inserm 1075 Comete, Unicaen
Caen, France
Investigator: Amir HODZIC, MD PhD
Contact: 0231065503
hodzic-a@chu-caen.fr
Amir HODZIC, MD PhD
0231065503
hodzic-a@chu-caen.fr
Hervé NORMAND, MD PhD
herve.normand@unicaen.fr
Not Provided