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... Show moreAim 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. Show less
Objective: The study objective was to analyze survival and incidence of Fontan completion of patients with single-ventricle and concomitant unbalanced atrioventricular septal defect. Methods: Data... Show moreObjective: The study objective was to analyze survival and incidence of Fontan completion of patients with single-ventricle and concomitant unbalanced atrioventricular septal defect. Methods: Data from 4 Dutch and 3 Belgian institutional databases were retrospectively collected. A total of 151 patients with single-ventricle atrioventricular septal defect were selected; 36 patients underwent an atrioventricular valve procedure (valve surgery group). End points were survival, incidence of Fontan completion, and freedom from atrioventricular valve reoperation. Results: Median follow-up was 13.4 years. Cumulative survival was 71.2%, 70%, and 68.5% at 10, 15, and 20 years, respectively. An atrioventricular valve procedure was not a risk factor for mortality. Patients with moderate-severe or severe atrioventricular valve regurgitation at echocardiographic follow-up had a significantly worse 15year survival (58.3%) compared with patients with no or mild regurgitation (89.2%) and patients with moderate regurgitation (88.6%) (P = .033). Cumulative incidence of Fontan completion was 56.5%, 71%, and 77.6% at 5, 10, and 15 years, respectively. An atrioventricular valve procedure was not associated with the incidence of Fontan completion. In the valve surgery group, freedom from atrioventricular valve reoperation was 85.7% at 1 year and 52.6% at 5 years. Conclusions: The long-term survival and incidence of Fontan completion in our study were better than previously described for patients with single-ventricle atrioventricular septal defect. A concomitant atrioventricular valve procedure did not increase the mortality rate or decrease the incidence of Fontan completion, whereas patients with moderate-severe or severe valve regurgitation at follow-up had a worse survival. Therefore, in patients with single-ventricle atrioventricular septal defect when atrioventricular valve regurgitation exceeds a moderate degree, the atrioventricular valve should be repaired. Show less
Background At the most severe end of the spectrum of congenital heart disease are patients with an univentricular physiology. They comprise a heterogeneous group of congenital heart malformations... Show moreBackground At the most severe end of the spectrum of congenital heart disease are patients with an univentricular physiology. They comprise a heterogeneous group of congenital heart malformations that have the common characteristic that the cardiac morphology is not equipped for sustaining a biventricular circulation. Case summary Here, we present a case of an adult patient after Fontan palliation, illustrative of the complex clinical course and the broad spectrum of complications that can be encountered during follow-up, highlighting the need for a multidisciplinary approach in the clinical care for these patients. Discussion During the surgical Fontan procedure, the inferior vena cava is connected to the pulmonary circulation, after prior connection of the superior vena cava to the pulmonary arterial circulation. The resulting cavopulmonary connection, thus lacking a subpulmonic ventricle, provides non-pulsatile passive flow of oxygen-poor blood from the systemic venous circulation into the lungs, and the functional monoventricle pumps the oxygen-rich pulmonary venous return blood into the aorta. With an operative mortality of <5% and current 30-year survival rates up to 85%, the adult population of patients with a Fontan circulation is growing. This increase in survival is, however, inevitably accompanied by long-term complications affecting multiple organ systems, resulting in decline in cardiovascular performance. Conclusion For optimal treatment, the evaluation in a multidisciplinary team is mandatory, using the specific expertise of the team members to timely detect and address late complications and to support quality of life. Show less
Harteveld, L.M.; Blom, N.A.; Monteros, C.T.E. de los; Kuipers, I.M.; Rammeloo, L.A.J.; Hazekamp, M.G.; ... ; Harkel, A.D.J. ten 2022
Many Fontan patients with and without systolic ventricular dysfunction are being treated with angiotensin-converting enzyme (ACE) inhibitors, despite its effectiveness remaining unclear. In the... Show moreMany Fontan patients with and without systolic ventricular dysfunction are being treated with angiotensin-converting enzyme (ACE) inhibitors, despite its effectiveness remaining unclear. In the present study, we evaluated the short-term effect of enalapril on exercise capacity, vascular and ventricular function in pediatric Fontan patients with moderategood systolic ventricular function. Fontan patients between 8 and 18 years with moderategood systolic ventricular function and without previous ACE inhibitor treatment were included and were treated with enalapril for 3 months. During the first 2 weeks, the dosage was titrated according to systolic blood pressure (SBP). Exercise tests, ventricular function assessed by echocardiography, arterial stiffness measurements, and plasma levels of N-terminal pro-B-type natriuretic peptide assessed before and after a 3-month enalapril treatment period was compared. A total of 28 Fontan patients (median age 13.9 years, 6 to 15 years after Fontan operation) completed the study with a mean dosage of 0.3 +/- 0.1 mg/ kg/d. A total of 6 patients (21 %) experienced a significant drop in SBP and 6 others (21%) experienced other adverse events. Enalapril treatment lowered the SBP (from 110 to 104 mmHg, p = 0.003) and levels of N-terminal pro-B-type natriuretic peptide (from 80 to 72 ng/L, p = 0.036). However, enalapril treatment did not improve exercise capacity, ventricular function, or arterial stiffness. In conclusion, short-term ACE inhibition has no beneficial effect in Fontan patients with moderate-good systolic ventricular function. (C) 2021 The Authors. Published by Elsevier Inc. Show less
Rijnberg, F.M.; Woude, S.F.S. van der; Hazekamp, M.G.; Boogaard, P.J. van den; Lamb, H.J.; Monteros, C.T.E. de los; ... ; Roest, A.A.W. 2021
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... Show moreOBJECTIVES: 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: V-conduit/V-IVC where V is the mean velocity.RESULTS: Median conduit CSA and IVC CSA were 221 mm(2) (Q1-Q3 201-255) and 244 mm(2) (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 1/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. Show less
OBJECTIVES: This review aims at presenting and summarizing the current state of literature on the presentation and surgical management of a right-sided aortic arch with a left-sided ligamentum... Show moreOBJECTIVES: This review aims at presenting and summarizing the current state of literature on the presentation and surgical management of a right-sided aortic arch with a left-sided ligamentum forming a complete vascular ring around the oesophagus and trachea.METHODS: A systematic database search for appropriate literature was conducted on PubMed/MEDLINE. Articles were considered relevant when providing details on the presentation, diagnosis and surgical treatment of this specific congenital arch anomaly in human beings.RESULTS: Affected patients present with respiratory and/or oesophageal difficulties due to tracheoesophageal compression. Conservative treatment might be reasonable in asymptomatic or mildly symptomatic cases; however, once moderate-to-severe symptoms develop, surgical intervention is definitely indicated. Surgery is commonly performed through a left thoracotomy or median sternotomy and includes the division of the left ductal ligamentum; if a Kommerell's diverticulum is present that is >1.5 times the diameter of the subclavian artery, then concomitant resection of the large diverticulum and translocation of the aberrant left subclavian artery is also conducted. Postoperative morbidity and mortality are low and are rather related to concomitant intracardiac and extracardiac anomalies than to the procedure itself. In a majority of patients, full resolution of symptoms is seen within months to years from the surgery. Nevertheless, there is also a subset of patients who remain with some tracheobronchial narrowing, sometimes even requiring reintervention during follow-up due to persisting or recurring symptoms.CONCLUSIONS: Overall, the surgical management of a right aortic arch forming a true vascular ring in infancy, childhood and adulthood seems relatively safe and effective in providing symptomatic relief despite some persistent tracheobronchial and/or oesophageal narrowing in some cases. Show less
Background: Although various determinants of exercise limitation in Fontan patients have been studied, most research has been performed in patients who underwent different surgical procedures with... Show moreBackground: Although various determinants of exercise limitation in Fontan patients have been studied, most research has been performed in patients who underwent different surgical procedures with differing haemodynamic characteristics. The aim of the current study was to evaluate non-invasively measured cardiovascular parameters and their influence on exercise performance in paediatric Fontan patients with an extracardiac conduit and moderate-good systolic ventricular function. Methods: Fontan patients, between 8 and 18 years of age, with moderate to good systolic ventricular function and an extracardiac conduit were included. Exercise performance and cardiovascular assessment, comprising echocardiography, aortic stiffness measurement and ambulatory measurement of cardiac autonomous nervous activity were performed on the same day. Healthy subjects served as controls. Results: Thirty-six Fontan patients (age 14.0 years) and thirty-five healthy subjects (age 12.8 years) were included. Compared to controls, Fontan patients had reduced diastolic ventricular function and increased arterial stiffness. No differences were found in heart rate (HR) and cardiac parasympathetic nervous activity. In Fontan patients, maximal as well as submaximal exercise capacity was impaired, with the percentage of predicted capacity ranging between 54 and 72%. Chronotropic competence, however, was good with a peak HR of 174 (94% of predicted). Lower maximal and submaximal exercise capacity was correlated with a higher HR at rest, higher pulse wave velocity of the aorta and a lower ratio of early and late diastolic flow velocity. Conclusion: Contemporary paediatric Fontan patients have an impaired exercise capacity with preserved chronotropic competence. Exercise performance correlates with heart rate at rest, diastolic function and aortic stiffness. Show less
Vliet, R. van; Kroft, L.J.M.; Hazekamp, M.G.; Roest, A.A.W.; Palen, R.L.F. van der 2021
We present a case of a prematurely born 2-month-old girl with a double outlet right ventricle with pulmonary atresia and a left pulmonary artery coarctation arising after ductal closure. The case... Show moreWe present a case of a prematurely born 2-month-old girl with a double outlet right ventricle with pulmonary atresia and a left pulmonary artery coarctation arising after ductal closure. The case highlights the importance of knowledge and identification of such an anomaly in patients with congenital heart malformations with severe pulmonary stenosis to atresia. Show less
Coronary artery status in adults long after the arterial switch operation (ASO) is unclear. We conducted a systematic review to provide an overview of coronary complications during adulthood and to... Show moreCoronary artery status in adults long after the arterial switch operation (ASO) is unclear. We conducted a systematic review to provide an overview of coronary complications during adulthood and to evaluate the value of routine coronary imaging in adults after ASO, in light of current guidelines. Articles were screened for the inclusion of adult ASO patients and data on coronary complications and findings of coronary imaging were collected. A total of 993 adults were followed with a median available follow-up of only 2.0 years after reaching adulthood. Myocardial ischemia was suspected in 17/192 patients (8.9%). The number of coronary interventions was four (0.4%), and coronary death was reported in four (0.4%) patients. A lack of ischemia-related symptoms cannot be excluded because innervation studies indicated deficient cardiac innervation after ASO, although data is limited. Anatomical high-risk features found by routine coronary computed tomography (cCT) included stenosis (4%), acute angle (40%), kinking (24%) and inter-arterial course (11%). No coronary complications were reported during pregnancy (n = 45), although, remarkably, four (9%) patients developed heart failure. The 2020 European Society of Cardiology (ESC) guidelines state that routine screening for coronary pathologies is questionable. Based on current findings and in line with the 2018 American ACC/AHA guidelines a baseline assessment of the coronary arteries in all ASO adults seems justifiable. Thereafter, an individualized coronary follow-up strategy is advisable at least until significant duration of follow-up is available. Show less
Monteros, C.T.E. de los; Harteveld, L.M.; Kuipers, I.M.; Rammeloo, L.; Hazekamp, M.G.; Blom, N.A.; Harkel, A.D.J. ten 2021
Background: The aim of this retrospective cohort study was to determine the incidence, potential risk factors, characteristics, and outcomes of acute kidney injury in children following the... Show moreBackground: The aim of this retrospective cohort study was to determine the incidence, potential risk factors, characteristics, and outcomes of acute kidney injury in children following the arterial switch operation for transposition of the great arteries. Methods: Retrospective review of children who underwent ASO between 2000 and 2020 in our tertiary children's hospital in the Netherlands. Pre-and post-ASO serum creatinine levels were collected. Severe AKI was defined as 100% serum creatinine rise or estimated creatinine clearance Results: A total of 242 children were included. Fifty-seven (24%) children developed severe AKI after ASO. Four patients with severe AKI were treated with renal replacement therapy. Children with severe AKI had a longer duration of mechanical ventilation 4.5 (1.0-29) versus 3 (1.0-12) days (p = 0.001), longer PICU stay 7 (2-76) versus 5 (1-70) days, (p = 0.001), higher rate of myocardial infarction 5% versus 0.5% (p = 0.001), sepsis 24% versus 9% (p = 0.002), post-operative pulmonary hypertension 19% versus 6% (p = 0.002), post-operative bleeding 9% versus 3% (p = 0.044), longer time to sternal closure 3 (1-19) versus 2 (1-6) days, (p = 0.009), and a higher mortality rate 9.0% versus 0.5% (p = 0.001) compared to children without severe AKI. Sepsis was a risk factor for developing severe AKI. Conclusions: In this single-centre cohort, 24% of our patients developed severe AKI after ASO, which is associated with increased morbidity, longer PICU stay, and higher mortality. Show less
Congenital heart disease is the most common birth defect and functionally univentricular heart defects represent the most severe end of this spectrum. The Fontan circulation provides an unique... Show moreCongenital heart disease is the most common birth defect and functionally univentricular heart defects represent the most severe end of this spectrum. The Fontan circulation provides an unique solution for single ventricle patients, by connecting both caval veins directly to the pulmonary arteries. As a result, the pulmonary circulation in Fontan palliated patients is characterized by a passive, low-energy circulation that depends on increased systemic venous pressure to drive blood toward the lungs. The absence of a subpulmonary ventricle led to the widely believed concept that respiration, by sucking blood to the pulmonary circulation during inspiration, is of great importance as a driving force for antegrade blood flow in Fontan patients. However, recent studies show that respiration influences pulsatility, but has a limited effect on net forward flow in the Fontan circulation. Importantly, since MRI examination is recommended every 2 years in Fontan patients, clinicians should be aware that most conventional MRI flow sequences do not capture the pulsatility of the blood flow as a result of the respiration. In this review, the unique flow dynamics influenced by the cardiac and respiratory cycle at multiple locations within the Fontan circulation is discussed. The impact of (not) incorporating respiration in different MRI flow sequences on the interpretation of clinical flow parameters will be covered. Finally, the influence of incorporating respiration in advanced computational fluid dynamic modeling will be outlined. Show less
Introduction: Anomalous aortic origin of a coronary artery (AAOCA) from the opposite sinus of Valsalva is a rare congenital abnormality. Computed tomography angiography (CTA) is primarily used as a... Show moreIntroduction: Anomalous aortic origin of a coronary artery (AAOCA) from the opposite sinus of Valsalva is a rare congenital abnormality. Computed tomography angiography (CTA) is primarily used as a diagnostic tool to evaluate the anatomy and identify potentially malignant AAOCA variants. Limited data is available on the role of CTA during postoperative follow-up. We aimed to develop an objective CTA derived parameter for diagnostic evaluation and follow-up after surgical correction of AAOCA and correlate the anatomical features to the postoperative outcome.Methods: All consecutive patients who underwent surgical repair of AAOCA from 2001 to 2018 and had pre and postoperative CTA imaging available were included. A retrospective analysis of the pre- and postoperative CTA and the outcomes was performed. The origin and course of the anomalous coronary artery and the ostial dimensions were evaluated and correlated with restenosis of operated coronary artery. To allow an accurate evaluation of the effective orifice area at diagnosis and after surgical repair we deduce and propose a new parameter-the coronary triangulated orifice area (CTOA).Results: Out of the 54 patients who underwent surgical treatment for AAOCA, 11 fulfilled the inclusion criteria. The median follow-up was 19 months [IQR 3;42]. The mean age at surgery was 41 +/- 16 years, with six patients (55%) being male. Postoperatively, the angle between the proximal coronary artery and the aortic wall increased from 20 +/- 5 degrees to 28 +/- 9 degrees (p < 0.01) and ostial diameter in the transversal plane increased from 4.1 +/- 2.5 mm to 6.2 +/- 2.7 mm (p < 0.01). The median CTOA increased significantly from 1.6 mm(2) [IQR 0.9;4.9] to 5.5 mm(2) [IQR 3;11.8] (p < 0.005). During follow-up, in three patients a restenosis of the operated coronary artery was suspected. In these patients, the CTOA only showed a limited postoperative increase of <= 1.4 mm(2).Conclusions: CTA can play an important role in the evaluation of the pre- and postoperative anatomy in AAOCA patients. CTOA may be of use in conjunction with the acute angle take-off and ostial diameter order to comprehensively evaluate the operated ostium after unroofing or patch angioplasty. Show less
Traumatic avulsion of the right main bronchus in children is usually caused by blunt trauma or traffic accidents. Primary repair by suturing is the preferred treatment. Lesions are life threatening... Show moreTraumatic avulsion of the right main bronchus in children is usually caused by blunt trauma or traffic accidents. Primary repair by suturing is the preferred treatment. Lesions are life threatening and urgent or emergency surgical repair is indicated. We report our experience with 2 cases of traumatic avulsion of right bronchus in children successfully suture repaired with the use of extracorporeal membrane oxygenation. Show less
OBJECTIVES: The objective of this study was to assess our 43-year experience with arterial switch operation (ASO) for transposition of the great arteries (TGA) by analysing cardiac outcome measures... Show moreOBJECTIVES: The objective of this study was to assess our 43-year experience with arterial switch operation (ASO) for transposition of the great arteries (TGA) by analysing cardiac outcome measures (hospital and late mortality, reoperations and catheter interventions, significant coronary artery obstruction) and to identify risk factors for reoperation and catheter interventions.METHODS: A total of 490 patients who underwent ASO for TGA from 1977 to 2020 were included in this retrospective, single-centre study. Data on reoperation and catheter intervention of hospital survivors were estimated by the Kaplan-Meier method and compared using a long-rank test. Risk factors for reoperation and/or catheter intervention were assessed by multivariate Cox regression analysis.RESULTS: Hospital mortality occurred in 43 patients (8.8%), late death in 12 patients (2.9%) and 43 patients were lost to follow-up. Median follow-up time of 413 hospital survivors was 15.6 (interquartile range 7.0-22.4) years. Reoperations were performed in 83 patients (117 reoperations). Neoaortic valve regurgitation with root dilatation was the second most common indication for reoperation (15/83 patients, 18.1%) after right ventricular outflow tract obstruction (50/83 patients, 60.2%). Risk factors for any reoperation on multivariable analysis were: TGA morphological subtype [TGA with ventricular septal defect: hazard ratio (HR)=1.99, 95% confidence interval (CI) 1.18-3.36; P=0.010 and Taussig-Bing: HR=2.17, 95% CI 1.02-4.64; P=0.045], aortic arch repair associated with ASO (HR=3.03, 95% CI 1.62-5.69; P=0.001) and a non-usual coronary artery anatomy (HR=2.41, 95% CI 1.45-4.00; P=0.001). One hundred and one catheter interventions were performed in 54 patients, usually for relief of supravalvular pulmonary stenosis (44/54 patients, 81.5%) or arch obstruction (10/54 patients, 18.5%). Main risk factor for catheter intervention on multivariable analysis was aortic arch repair associated with ASO (HR=2.95, 95% CI 1.37-6.36; P=0.006). Significant coronary artery stenosis was relatively uncommon (9/413 patients, 2.2%) but may be underrepresented.CONCLUSIONS: Patients after ASO typically have good long-term clinical outcomes but reoperations and interventions remain necessary in some patients. Neoaortic valve regurgitation with root dilatation is the second most common indication for reoperation after right ventricular outflow tract obstruction and an increasing need for neoaortic valve and root redo surgery in future is to be expected. Show less
Fontan patients require a balanced hepatic blood flow distribution (HFD) to prevent pulmonary arteriovenous malformations. Currently, HFD is quantified by tracking Fontan conduit flow, assuming... Show moreFontan patients require a balanced hepatic blood flow distribution (HFD) to prevent pulmonary arteriovenous malformations. Currently, HFD is quantified by tracking Fontan conduit flow, assuming hepatic venous (HV) flow to be uniformly distributed within the Fontan conduit. However, this assumption may be unvalid leading to inaccuracies in HFD quantification with potential clinical impact. The aim of this study was to (i) assess the mixing of HV flow and inferior vena caval (IVC) flow within the Fontan conduit and (ii) quantify HFD by directly tracking HV flow and quantitatively comparing results with the conventional approach. Patient-specific, time-resolved computational fluid dynamic models of 15 total cavopulmonary connections were generated, including the HV and subhepatic IVC. Mixing of HV and IVC flow, on a scale between 0 (no mixing) and 1 (perfect mixing), was assessed at the caudal and cranial Fontan conduit. HFD was quantified by tracking particles from the caudal (HFDcaudal conduit) and cranial (HFDcranial conduit) conduit and from the hepatic veins (HFDHV). HV flow was non-uniformly distributed at both the caudal (mean mixing 0.66 +/- 0.13) and cranial (mean 0.79 +/- 0.11) level within the Fontan conduit. On a cohort level, differences in HFD between methods were significant but small; HFDHV (51.0 +/- 20.6%) versus HFDcaudal conduit (48.2 +/- 21.9%, p = 0.033) or HFDcranial conduit (48.0 +/- 21.9%, p = 0.044). However, individual absolute differences of 8.2-14.9% in HFD were observed in 4/15 patients. HV flow is non-uniformly distributed within the Fontan conduit. Substantial individual inaccuracies in HFD quantification were observed in a subset of patients with potential clinical impact. Show less
