Effect of Midazolam and Dexmedetomidine on Heart Function - A Randomized MRI-based Study.

The study will test the hypothesis that the use of dexmedetomidine leads to less negative impact on ventricular function compared to midazolam.

The study will include patients who will meet the inclusion criteria. A previous, yet unpublished, pilot study assured that a number of 15 participants in each arm is sufficient to detect statistical significant results with a statistical power of ≥ 80%. After signing the informed consent, a one-session cardiac MRI will be performed in each fasting participant before and after sedation administration (see arms and intervention). The following parameters will be recorded: end diastolic and end systolic volume, left and right ventricle stroke volume and flow velocity through the mitral valve during early and late diastole. A monitor will record values of mean blood pressure, pulse and blood oxygen saturation in 5-minute intervals.

The acquired data will be transferred to an offline workstation for postprocessing and quantification. In participants we will calculate left ventricular volumes using the well-known Simpson's formula by segmenting of endocardial borders on end-diastolic and end-systolic frames on every slice through the left ventricle.

The quantitative flow measurement will be performed using phase contrast quantification flow mapping.

Statistical analyses will be performed using STATISTICA software (data analysis software system, version 13 TIBCO Software Inc). All values will be presented as average ± standard deviation. Analysis of variance for repeated measures with post hoc Fisher's LSD test will be used for statistical testing of significant differences in each group and between the groups before and after sedation, respectively. Significance level will be accepted at α<0.05.