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

Background: Congenital heart disease (CHD) is often associated with chronic right ventricular (RV) volume overload. Real-time magnetic resonance imaging (MRI) allows the analysis of cardiac function under physiological conditions during free-breathing, providing the opportunity to evaluate the influence of breathing on cardiac function as a dynamic parameter of RV function.

Methods: Six pediatric CHD patients with chronic RV volume overload and six healthy pediatric controls were recruited for cardiac real-time MR volumetry imaging at 1.5 T during free-breathing. Breathing curves obtained from regions of interest reflecting the position of the diaphragm served for respiratory binning of MR-images. Tidal volumes were estimated by calibration using data previously obtained by MR-compatible spirometry. Ventricular volumes indexed to body surface area (BSA) and Frank-Starling relationships were calculated and referenced to the typical tidal volume indexed to body height (TTVi) for comparison.

Results: Indexed RV end-diastolic volume (RV-EDVi) and indexed RV stroke volume (RV-SVi) increased during inspiration (RV-EDVi/TTVi: RV load: +16 ± 4%; controls: +22 ± 13%; RV-SVi/TTVi: RV load: +21 ± 6%; controls: +35 ± 17%; non-significant for comparison). The increase in RV ejection fraction during inspiration was significantly lower in RV load patients (RV load: +1.1 ± 2.2%; controls: +6.1 ± 1.5%; p = 0.01). The Frank-Starling relationship of the RV provided a significantly reduced slope estimate in RV load patients (inspiration: RV load: 0.75 ± 0.11; controls: 0.92 ± 0.02; p = 0.02).

Conclusion: In pediatric CHD patients with chronic RV volume overload, cardiac real-time MRI under physiological conditions during free breathing in combination with respiratory-based binning indicates an impaired Frank–Starling relationship of the RV, thereby providing a noninvasive, dynamic parameter of right ventricular function.

Publication History

Article published online:
13 February 2024