Hemodynamic Consequences of an Undersized Extracardiac Conduit in an Adult Fontan Patient Revealed by 4-Dimensional Flow Magnetic Resonance Imaging

Rijnberg, Friso M; Assen, Hans C van; Hazekamp, Mark G.; Roest, Arno A.W.; Westenberg, Jos J.M.

doi:10.1161/circimaging.121.012612

Cited by 7 publications

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References 4 publications

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“…In a large study of CFD simulations during resting conditions, patients with small Fontan conduits showed a three-fold higher TCPC resistance compared to the mean resistance of the entire study cohort, potentially reaching values up to 35–50% of normal pulmonary vascular resistance [ 5 ]. TCPC resistance further increases exponentially during exercise [ 22 ] while pulmonary vascular resistance decreases during exercise [ 23 ], making TCPCs with a relatively undersized conduit a potential bottleneck in the Fontan circulation [ 4 , 24 ].…”

Section: Discussionmentioning

confidence: 99%

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Extracardiac conduit adequacy along the respiratory cycle in adolescent Fontan patients

Rijnberg

Woude

Hazekamp

et al. 2021

European Journal of Cardio-Thoracic Surgery

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OBJECTIVES Adequacy of 16–20mm extracardiac conduits for adolescent Fontan patients remains unknown. This study aims to evaluate conduit adequacy using the inferior vena cava (IVC)–conduit velocity mismatch factor along the respiratory cycle. METHODS Real-time 2D flow MRI was prospectively acquired in 50 extracardiac (16–20mm conduits) Fontan patients (mean age 16.9 ± 4.5 years) at the subhepatic IVC, conduit and superior vena cava. Hepatic venous flow was determined by subtracting IVC flow from conduit flow. The cross-sectional area (CSA) was reported for each vessel. Mean flow and velocity was calculated during the average respiratory cycle, inspiration and expiration. The IVC–conduit velocity mismatch factor was determined as follows: Vconduit/VIVC, where V is the mean velocity. RESULTS Median conduit CSA and IVC CSA were 221 mm2 (Q1–Q3 201–255) and 244 mm2 (Q1–Q3 203–265), respectively. From the IVC towards the conduit, flow rates increased significantly due to the entry of hepatic venous flow (IVC 1.9, Q1–Q3 1.5–2.2) versus conduit (3.3, Q1–Q3 2.5–4.0 l/min, P < 0.001). Consequently, mean velocity significantly increased (IVC 12 (Q1–Q3 11–14 cm/s) versus conduit 25 (Q1–Q3 17–31 cm/s), P < 0.001), resulting in a median IVC–conduit velocity mismatch of 1.8 (Q1–Q3 1.5–2.4), further augmenting during inspiration (median 2.3, Q1–Q3 1.8–3.0). IVC–conduit mismatch was inversely related to measured conduit size and positively correlated with conduit flow. The normalized IVC–conduit velocity mismatch factor during expiration and the entire respiratory cycle correlated with peak VO2 (r = –0.37, P = 0.014 and r = –0.31, P = 0.04, respectively). CONCLUSIONS Important blood flow accelerations are observed from the IVC towards the conduit in adolescent Fontan patients, which is related to peak VO2. This study, therefore, raises concerns that implanted 16–20mm conduits have become undersized for older Fontan patients and future studies should clarify its effect on long-term outcome.

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Section: Discussionmentioning

confidence: 99%

“…The acceleration of blood flow in the conduit may also have adverse effects on downstream energy-consuming flow patterns (e.g. vortices, helices) or caval flow collision within the Fontan confluence, further decreasing TCPC flow efficiency [ 24 ].…”

Section: Discussionmentioning

confidence: 99%

Extracardiac conduit adequacy along the respiratory cycle in adolescent Fontan patients

Rijnberg

Woude

Hazekamp

et al. 2021

European Journal of Cardio-Thoracic Surgery

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“…Drawbacks of CFD modelling are that it is time-consuming and requires expert knowledge and infrastructure, limiting widespread use in clinical care. 4D flow cardiovascular magnetic resonance imaging (CMR) is emerging as a non-invasive screening tool for visualization of energy-consuming flow patterns in the TCPC and quantification of flow-related hemodynamic parameters including kinetic energy (KE) and viscous energy loss rate (EL) [ 8 – 10 ].The hypothesis in this study is that these in vivo 4D flow CMR-derived energetics in the TCPC are associated with exercise capacity and liver fibrosis/congestion. Subsequently, the aim of this study is to determine KE and EL in the TCPC using 4D flow CMR and to assess the relationship with exercise capacity and CMR-based assessment of liver fibrosis/congestion.…”

Section: Introductionmentioning

confidence: 99%

4D flow cardiovascular magnetic resonance derived energetics in the Fontan circulation correlate with exercise capacity and CMR-derived liver fibrosis/congestion

Rijnberg

Westenberg

Assen

et al. 2022

Journal of Cardiovascular Magnetic Resonance

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Aim This study explores the relationship between in vivo 4D flow cardiovascular magnetic resonance (CMR) derived blood flow energetics in the total cavopulmonary connection (TCPC), exercise capacity and CMR-derived liver fibrosis/congestion. Background The Fontan circulation, in which both caval veins are directly connected with the pulmonary arteries (i.e. the TCPC) is the palliative approach for single ventricle patients. Blood flow efficiency in the TCPC has been associated with exercise capacity and liver fibrosis using computational fluid dynamic modelling. 4D flow CMR allows for assessment of in vivo blood flow energetics, including kinetic energy (KE) and viscous energy loss rate (EL). Methods Fontan patients were prospectively evaluated between 2018 and 2021 using a comprehensive cardiovascular and liver CMR protocol, including 4D flow imaging of the TCPC. Peak oxygen consumption (VO2) was determined using cardiopulmonary exercise testing (CPET). Iron-corrected whole liver T1 (cT1) mapping was performed as a marker of liver fibrosis/congestion. KE and EL in the TCPC were computed from 4D flow CMR and normalized for inflow. Furthermore, blood flow energetics were compared between standardized segments of the TCPC. Results Sixty-two Fontan patients were included (53% male, 17.3 ± 5.1 years). Maximal effort CPET was obtained in 50 patients (peak VO2 27.1 ± 6.2 ml/kg/min, 56 ± 12% of predicted). Both KE and EL in the entire TCPC (n = 28) were significantly correlated with cT1 (r = 0.50, p = 0.006 and r = 0.39, p = 0.04, respectively), peak VO2 (r = − 0.61, p = 0.003 and r = − 0.54, p = 0.009, respectively) and % predicted peak VO2 (r = − 0.44, p = 0.04 and r = − 0.46, p = 0.03, respectively). Segmental analysis indicated that the most adverse flow energetics were found in the Fontan tunnel and left pulmonary artery. Conclusions Adverse 4D flow CMR derived KE and EL in the TCPC correlate with decreased exercise capacity and increased levels of liver fibrosis/congestion. 4D flow CMR is promising as a non-invasive screening tool for identification of patients with adverse TCPC flow efficiency.

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“…Offsetting of the caval anastomoses was recognized early on, and adaptations for the Fontan connection reducing power loss have been suggested. Oftentimes, the size of the Fontan conduit (either small from the beginning, or reduced in size whilst aging) may result in suboptimal hemodynamics which will be exacerbated during exercise as assessed by 4D MRI flow (31)(32)(33). Likely optimizing the Fontan conduit early in life (allowing sufficient pulmonary artery growth and additional shunt if needed) and later in life (stenting of the conduit to adult size or stenting of a hypoplastic left pulmonary artery if present) are required to maintain optimal Fontan hemodynamics as long as possible (5).…”

Section: Fontan During Exercisementioning

confidence: 99%

Late Fontan Circulatory Failure. What Drives Systemic Venous Congestion and Low Cardiac Output in Adult Fontan Patients?

Bruaene

Claessen

Salaets

et al. 2022

Front. Cardiovasc. Med.

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The Fontan circulation provides definite palliation for children born with a single anatomical or functional ventricle by diverting systemic venous blood directly to the pulmonary arteries, effectively rendering systemic venous return into portal vessels to the lung. Although this restores pulmonary blood flow and avoids the mixture of oxygenated and deoxygenated blood, it also results in elevated systemic venous pressures and low cardiac output. These are the two hallmarks of any Fontan circulation and the cause of Fontan circulatory failure later in life. We highlight the determinants of systemic venous return, its changed relationship with the pulmonary circulation, how it affects preload, and the changed role of the heart (myocardium, valves, and heart rate). By critically evaluating the components of the Fontan circulation, we hope to give some clues in how to optimize the Fontan circulation and avenues for future research.

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Hemodynamic Consequences of an Undersized Extracardiac Conduit in an Adult Fontan Patient Revealed by 4-Dimensional Flow Magnetic Resonance Imaging

Abstract: Supplemental Digital Content is available in the text.

Cited by 7 publications

References 4 publications

Extracardiac conduit adequacy along the respiratory cycle in adolescent Fontan patients

Extracardiac conduit adequacy along the respiratory cycle in adolescent Fontan patients

4D flow cardiovascular magnetic resonance derived energetics in the Fontan circulation correlate with exercise capacity and CMR-derived liver fibrosis/congestion

Late Fontan Circulatory Failure. What Drives Systemic Venous Congestion and Low Cardiac Output in Adult Fontan Patients?

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