Stress increases intracardiac 4D flow cardiovascular magnetic resonance -derived energetics and vorticity and relates to VO2max in Fontan patients

Abstract

Background We hypothesize that dobutamine-induced stress impacts intracardiac hemodynamic parameters and that this may be linked to decreased exercise capacity in Fontan patients . Therefore, the purpose of this study was to assess the effect of pharmacologic stress on intraventricular kinetic energy (KE), viscous energy loss (EL) and vorticity from four-dimensional (4D) Flow cardiovascular magnetic resonance (CMR) imaging in Fontan patients and to study the association between stress response and exercise capacity. Methods Ten Fontan patients underwent whole-heart 4D flow CMR before and during 7.5 μg/kg/min dobutamine infusion and cardiopulmonary exercise testing (CPET) on the same day. Average ventricular KE, EL and vorticity were computed over systole, diastole and the total cardiac cycle (vorticity_vol avg cycle , KE avg cycle, EL avg cycle ). The relation to maximum oxygen uptake (VO 2 max) from CPET was tested by Pearson’s correlation or Spearman’s rank correlation in case of non-normality of the data. Results Dobutamine stress caused a significant 88 ± 52% increase in KE (KE avg cycle : 1.8 ± 0.5 vs 3.3 ± 0.9 mJ, P < 0.001), a significant 108 ± 49% increase in EL (EL avg cycle : 0.9 ± 0.4 vs 1.9 ± 0.9 mW, P < 0.001) and a significant 27 ± 19% increase in vorticity (vorticity_vol avg cycle : 3441 ± 899 vs 4394 ± 1322 mL/s, P = 0.002). All rest-stress differences (%) were negatively correlated to VO 2 max (KE avg cycle : r = − 0.83, P = 0.003; EL avg cycle : r = − 0.80, P = 0.006; vorticity_vol avg cycle : r = − 0.64, P = 0.047). Conclusions 4D flow CMR-derived intraventricular kinetic energy, viscous energy loss and vorticity in Fontan patients increase during pharmacologic stress and show a negative correlation with exercise capacity measured by VO 2 max.

Imaging of complications following Fontan circulation in children — diagnosis and surveillance

“…Axial contrast-enhanced T1-W gradient echo sequence (n) and T2-weighted sequence (o) reveal a slightly enlarged liver with peripheral enhancement pattern and perisinusoidal sparing, consistent with liver congestion in clinical use in a few institutions and require specific software analysis tools (Fig. 8) [37][38][39]. MR strain analysis and feature tracking are, like echocardiography, newer techniques that are garnering more attention to how diastolic and systolic function perform in the single-ventricle circulation and also in pediatric patients [28,34].…”

Left ventricular four-dimensional blood flow distribution, energetics, and vorticity in chronic myocardial infarction patients with/without left ventricular thrombus

“…Vorticity refers to the local spinning of blood particles and numerous factors may affect the generation of vorticity including flow velocity gradients and flow directionality. The increase in vorticity can lead to favorable effects such as conservation of momentum by KE storage but also some adverse effects when the optimal flow direction is disturbed due to abnormal intra-cardiac structures [26]. Previously, this hemodynamic parameter was found to be associated with ventricular diastolic dysfunction in different clinical settings and reduced LV vorticity values were observed in patients with chronic obstructive pulmonary disease [19,20].…”

Acute vasodilator response testing in the adult Fontan circulation using non-invasive 4D Flow MRI: a proof-of-principle study

“…[23][24][25] Furthermore, dobutamine stress MRI has shown to increase systolic kinetic energy in the Fontan circulation, and a larger kinetic energy increase was associated with markers of reduced exercise tolerance. 21 It has been suggested that increased systolic peak kinetic energy indicates a lower efficiency in the cardiac circulation, as there is a higher workload required to pump a lower volume of blood. 20 This higher systolic kinetic energy in the ventricle may also be a marker for ventricular dysfunction.…”