First experience with real-time magnetic resonance imaging-based investigation of respiratory influence on cardiac function in pediatric congenital heart disease patients with chronic right ventricular volume overload

Figures

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  Fig. 1. Respiratory signal. Exemplary illustration (slices 10–12) demonstrating the processing of image-based respiratory signals. a Respiratory-related diaphragmatic movement was monitored by the median SI of manually selected ROI (white squares). b Rescaling, removal of outliers, and assessment of at least five consecutive respiratory cycles resulted in a good estimate of the tidal volume. c Real-time magnetic resonance images were binned based on SI values and ECG in rearranged heart cycles with 25 phases in eight respiratory classes (four different tidal volume classes both in inspiration and expiration). ECG electrocardiogram, MRI magnetic resonance imaging, ROI region(s) of interest, SI signal intensity

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  Fig. 2. Right ventricular volumes. Mean values (± SD) of right ventricular end-diastolic volume, end-systolic volume, stroke volume, and ejection fraction indexed to the body surface area as a function of the estimated tidal volume indexed to body height in inspiration (a–d) and expiration (e–h) for patients with right ventricular overload (blue) and controls (green). Results of the corresponding linear regression analyses are inserted in the graphs. Circles indicate mean value, whiskers, SD. *P<0.05 (linear regression). EDVi end-diastolic volume indexed to body surface area, ESVi end-systolic volume indexed to body surface area, SVi stroke volume indexed to body surface area, EF ejection fraction, SD standard deviation

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  Fig. 3. Left ventricular volumes. Mean values (± SD) of left ventricular end-diastolic volume, end-systolic volume, stroke volume, and ejection fraction indexed to the body surface area as a function of the estimated tidal volume indexed to body height in inspiration (a–d) and expiration (e–h) for right ventricular overload patients (blue) and controls (green). Results of the corresponding linear regression analyses are inserted in the graphs. Circles indicate mean value, whiskers, SD. *P<0.05 (linear regression). EDVi end-diastolic volume indexed to body surface area, ESVi end-systolic volume indexed to body surface area, SVi stroke volume indexed to body surface area, EF ejection fraction, SD standard deviation

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  Fig. 4. Frank-Starling relationship. Relationship between stroke volume and end-diastolic volume indexed to the body surface area for right patients with ventricle (a) and left ventricle (b) in inspiration and expiration for right ventricular overload (blue) and controls (green). Results of the corresponding linear regression analyses are inserted in the graphs. Note, while the right ventricular end-diastolic volume gets larger during inspiration, the left ventricular end-diastolic volume gets larger during expiration. Circles indicate mean value, whiskers standard deviation. *P<0.05 (linear regression). LV-EDVi left ventricular end-diastolic volume indexed to body surface area, LV-SVi left ventricular stroke volume indexed to body surface area, RV-EDVi right ventricular end-diastolic volume indexed to body surface area, RV-SVi right ventricular end-diastolic volume indexed to body surface area