Assessment of hemodynamic responses to exercise in aortic coarctation using MRI-ergometry in combination with computational fluid dynamics

Abstract

In patients with aortic coarctation it would be desirable to assess pressure gradients as well as information about blood flow profiles at rest and during exercise. We aimed to assess the hemodynamic responses to physical exercise by combining MRI-ergometry with computational fluid dynamics (CFD). MRI was performed on 20 patients with aortic coarctation (13 men, 7 women, mean age 21.5 ± 13.7 years) at rest and during ergometry. Peak systolic pressure gradients, wall shear stress (WSS), secondary flow degree (SFD) and normalized flow displacement (NFD) were calculated using CFD. Stroke volume was determined based on MRI. On average, the pressure gradient was 18.0 ± 16.6 mmHg at rest and increased to 28.5 ± 22.6 mmHg (p < 0.001) during exercise. A significant increase in cardiac index was observed (p < 0.001), which was mainly driven by an increase in heart rate (p < 0.001). WSS significantly increased during exercise (p = 0.006), whereas SFD and NFD remained unchanged. The combination of MRI-ergometry with CFD allows assessing pressure gradients as well as flow profiles during physical exercise. This concept has the potential to serve as an alternative to cardiac catheterization with pharmacological stress testing and provides hemodynamic information valuable for studying the pathophysiology of aortic coarctation.

Coarctation of Aorta Fluid Dynamics after Three-Dimensional Reconstruction: A Case Report and Literature Review

“…CFD can be used as an essential description to solve the current problem as it has largely replaced geometrical "algorithms" after the study of angles and proportions, which could not comprehensively re ect the whole picture of aortic dysplasia. Moreover, the current clinical database of the accuracy of CFD application is still scarce, and little is known about it nationally [21], and the calculation of the pressure gradient at the constriction by CFD using MRI images was performed in Germany in 2015 [18]. Let us consider the technology's far-reaching and detectable value, with CTA performed more often in domestic children due to MRI machines' selfcontained uid analysis software and younger infants and young children's MRI suffers from heart rate and examination time.…”

Exercise Cardiovascular Magnetic Resonance: A Review

“…69,70 New techniques using 4D flow during exercise has recently been shown to be feasible in a cohort of patients with aortic coarctation with or without prior stenting, suggesting a capacity to quantify pressure gradients across the stenotic portion during conditions of exertion. 94 Thus, exercise cardiovascular MRI shows promise in becoming a useful clinical tool in congenital heart disease, especially as survival continues to increase and the number of adults with these conditions and associated chronic morbidity requiring repeat interventions rises.…”

Hemodynamic Modeling of Biological Aortic Valve Replacement Using Preoperative Data Only

“…SFD quantifies the amount of secondary flow while incorporating vessel orientation, unlike helicity, for example. It has previously been used to characterize aortic flows in the presence of valve prostheses ( 4 ), to evaluate hemodynamic reactions to exercise ( 5 ), and is related to wall shear stress ( 6 ). Regarding NFD, several groups identified an association between increased NFD and aortic dilation ( 7 – 9 ), while others found it to be related to left ventricular remodeling ( 10 ).…”