Haemodynamic performance of 16–20-mm extracardiac Goretex conduits in adolescent Fontan patients at rest and during simulated exercise

OBJECTIVES: To date, it is not known if 16–20-mm extracardiac conduits are outgrown during somatic growth from childhood to adolescence. This study aims to determine total cavopulmonary connection (TCPC) haemodynamics in adolescent Fontan patients at rest and during simulated exercise and to assess the relationship between conduit size and haemodynamics. METHODS: Patient-specific, magnetic resonance imaging-based computational fluid dynamic models of the TCPC were performed in 51 extracardiac Fontan patients with 16–20-mm conduits. Power loss, pressure gradient and normalized resistance were quantified in rest and during simulated exercise. The cross-sectional area (CSA) (mean and minimum) of the vessels of the TCPC was determined and normalized for flow rate (mm2/l/min). Peak (predicted) oxygen uptake was assessed. RESULTS: The median age was 16.2 years (Q1–Q3 14.0–18.2). The normalized mean conduit CSA was 35–73% smaller compared to the inferior and superior vena cava, hepatic veins and left/right pulmonary artery (all P &lt; 0.001). The median TCPC pressure gradient was 0.7 mmHg (Q1–Q3 0.5–0.8) and 2.0 (Q1–Q3 1.4–2.6) during rest and simulated exercise, respectively. A moderate–strong inverse nonlinear relationship was present between normalized mean conduit CSA and TCPC haemodynamics in rest and exercise. TCPC pressure gradients of &gt;_1.0 at rest and &gt;_3.0 mmHg during simulated exercise were observed in patients with a conduit CSA &lt;_ 45 mm2/l/min and favourable haemodynamics (&lt;1 mmHg during both rest and exercise) in conduits &gt;_125 mm2/l/min. Normalized TCPC resistance correlated with (predicted) peak oxygen uptake. CONCLUSIONS: Extracardiac conduits of 16–20 mm have become relatively undersized in most adolescent Fontan patients leading to suboptimal haemodynamics.</p

A 45-year experience with the Fontan procedure: tachyarrhythmia, an important sign for adverse outcome

OBJECTIVES: This study aims to evaluate our 45-year experience with the Fontan procedure and to identify risk factors for late mortality and morbidity. METHODS: Demographic, preoperative, perioperative and postoperative characteristics were retrospectively collected for all patients who underwent a Fontan procedure in a single centre between 1972 and 2016. RESULTS: The study included 277 Fontan procedures (44 atriopulmonary connections, 28 Fontan-Björk, 42 lateral tunnels and 163 extracardiac conduits). Early failure occurred in 17 patients (6.1%). Median follow-up of the study cohort was 11.9 years (Q1-Q3 7.6-17.5). Longest survival estimates were 31% [95% confidence intervals (CI) 18-44%] at 35 years for atriopulmonary connection/Björk, 87% (95% CI 63-96%) at 20 years for lateral tunnel and 99% (95% CI 96-100%) at 15 years for extracardiac conduit. Estimated freedom from Fontan failure (death, heart transplant, take-down, protein-losing enteropathy, New York Heart Association III-IV) at 15 years was 65% (95% CI 52-76%) for atriopulmonary connection/Björk, 90% (95% CI 73-97%) for lateral tunnel and 90% (95% CI 82-94%) for extracardiac conduit. The development of tachyarrhythmia was an important predictor of Fontan failure [hazard ratio (HR) 2.6, 95% CI 1.2-5.8; P = 0.017], thromboembolic/neurological events (HR 3.6, 95% CI 1.4-9.4; P = 0.008) and pacemaker for sinus node dysfunction (HR 3.7, 95% CI 1.4-9.6; P = 0.008). Prolonged pleural effusion (>21 days) increased the risk of experiencing protein-losing enteropathy (HR 4.7, 95% CI 2.0-11.1; P < 0.001). CONCLUSIONS: With modern techniques, survival and freedom from Fontan failure are good. However, Fontan patients remain subject to general attrition. Tachyarrhythmia is an important sign for an adverse outcome. Prevention and early treatment of tachyarrhythmia may, therefore, be paramount in improving the long-term outcome

A 45-year experience with the Fontan procedure: tachyarrhythmia, an important sign for adverse outcome

OBJECTIVES: This study aims to evaluate our 45-year experience with the Fontan procedure and to identify risk factors for late mortality and morbidity. METHODS: Demographic, preoperative, perioperative and postoperative characteristics were retrospectively collected for all patients who underwent a Fontan procedure in a single centre between 1972 and 2016. RESULTS: The study included 277 Fontan procedures (44 atriopulmonary connections, 28 Fontan-Björk, 42 lateral tunnels and 163 extracardiac conduits). Early failure occurred in 17 patients (6.1%). Median follow-up of the study cohort was 11.9 years (Q1-Q3 7.6-17.5). Longest survival estimates were 31% [95% confidence intervals (CI) 18-44%] at 35 years for atriopulmonary connection/Björk, 87% (95% CI 63-96%) at 20 years for lateral tunnel and 99% (95% CI 96-100%) at 15 years for extracardiac conduit. Estimated freedom from Fontan failure (death, heart transplant, take-down, protein-losing enteropathy, New York Heart Association III-IV) at 15 years was 65% (95% CI 52-76%) for atriopulmonary connection/Björk, 90% (95% CI 73-97%) for lateral tunnel and 90% (95% CI 82-94%) for extracardiac conduit. The development of tachyarrhythmia was an important predictor of Fontan failure [hazard ratio (HR) 2.6, 95% CI 1.2-5.8; P = 0.017], thromboembolic/neurological events (HR 3.6, 95% CI 1.4-9.4; P = 0.008) and pacemaker for sinus node dysfunction (HR 3.7, 95% CI 1.4-9.6; P = 0.008). Prolonged pleural effusion (>21 days) increased the risk of experiencing protein-losing enteropathy (HR 4.7, 95% CI 2.0-11.1; P < 0.001). CONCLUSIONS: With modern techniques, survival and freedom from Fontan failure are good. However, Fontan patients remain subject to general attrition. Tachyarrhythmia is an important sign for an adverse outcome. Prevention and early treatment of tachyarrhythmia may, therefore, be paramount in improving the long-term outcome

Four-dimensional flow magnetic resonance imaging-derived blood flow energetics of the inferior vena cava-to-extracardiac conduit junction in Fontan patients

OBJECTIVES: In patients with the Fontan circulation, systemic venous return flows passively towards the lungs. Because of the absence of the subpulmonary ventricle, favourable blood flow patterns with minimal energy loss are clinically relevant. The region where the inferior vena cava, the hepatic veins and the extracardiac conduit join (IVC-conduit junction) is a potential source of increased energy loss. The aim of this study was to evaluate the relationship between geometry and blood flow patterns in the IVC-conduit junction with associated kinetic energy and energy loss using 4-dimensional flow magnetic resonance imaging (MRI). METHODS: Fourteen extracardiac conduit-Fontan patients underwent 4-dimensional flow MRI. The IVC-conduit junctions were ranked into 3 groups for 3 categories: the geometry, the flow complexity and the conduit mean velocity. The relative increase in the mean velocity from the IVC to the conduit (representing IVC-conduit mismatch) was determined. The peak kinetic energy and mean kinetic energy and energy loss were determined and normalized for volume. RESULTS: In 4 of 14 patients, adverse geometries led to helical flow patterns and/or acute changes in flow direction. For each category, the most adverse IVC-conduit junctions were associated with an approximate 2.3-3.2-fold and 2.0-2.9-fold increase in kinetic energy and energy loss, respectively. The IVC-conduit mismatch is strongly correlated with the mean kinetic energy and energy loss (r  = 0.80, P  =  0.001 and ρ = 0.83, P <  0.001, respectively) and with body surface area in patients with 16- mm conduits (r  =  0.88, P  =  0.010). CONCLUSIONS: The IVC-conduit junction is a potential source of increased energy loss. Junctions with increased energy loss showed: (i) a distorted geometry leading to adverse blood flow patterns and/or (ii) the IVC-conduit mismatch. Sixteen-millimetre conduits appear to be inadequate for older patients

Four-dimensional flow magnetic resonance imaging-derived blood flow energetics of the inferior vena cava-to-extracardiac conduit junction in Fontan patients

In patients with the Fontan circulation, systemic venous return flows passively towards the lungs. Because of the absence of the subpulmonary ventricle, favourable blood flow patterns with minimal energy loss are clinically relevant. The region where the inferior vena cava, the hepatic veins and the extracardiac conduit join (IVC conduit junction) is a potential source of increased energy loss. The aim of this study was to evaluate the relationship between geometry and blood flow patterns in the IVC conduit junction with associated kinetic energy and energy loss using 4-dimensional flow magnetic resonance imaging (MRI). METHODS: Fourteen extracardiac conduit-Fontan patients underwent 4-dimensional flow MRI. The IVC conduit junctions were ranked into 3 groups for 3 categories: the geometry, the flow complexity and the conduit mean velocity. The relative increase in the mean velocity from the IVC to the conduit (representing IVC conduit mismatch) was determined. The peak kinetic energy and mean kinetic energy and energy loss were determined and normalized for volume. In 4 of 14 patients, adverse geometries led to helical flow patterns and/or acute changes in flow direction. For each category, the most adverse IVC conduit junctions were associated with an approximate 2.3 3.2-fold and 2.0 2.9-fold increase in kinetic energy and energy loss, respectively. The IVC conduit mismatch is strongly correlated with the mean kinetic energy and energy loss (r = 0.80, P = 0.001 and q = 0.83, P 0.001, respectively) and with body surface area in patients with 16-mm conduits (r = 0.88, P = 0.010). The IVC conduit junction is a potential source of increased energy loss. Junctions with increased energy loss showed: (i) a distorted geometry leading to adverse blood flow patterns and/or (ii) the IVC conduit mismatch. Sixteen-millimetre conduits appear to be inadequate for older patients

Aortopexy for the treatment of tracheobronchomalacia in 100 children: a 10-year single-centre experience

OBJECTIVES Our study describes and analyses the results from aortopexy for the treatment of airway malacia in children. METHODS Demographic data, characteristics and preoperative, operative and outcome details, including the need for reintervention, were collected for children undergoing aortopexy between 2006 and 2016. RESULTS One hundred patients [median age 8.2 months, interquartile range (IQR) 3.3-26.0 months] underwent aortopexy. Sixty-four (64%) patients had tracheomalacia (TM) only, 24 (24%) patients had TM extending into their bronchus (tracheobronchomalacia) and 11 (11%) patients had bronchomalacia. Forty-one (41%) children had gastro-oesophageal reflux disease, of which 17 (41%) children underwent a Nissen fundoplication. Twenty-eight (28%) children underwent a tracheo-oesophageal fistula repair prior to aortopexy (median 5.7 months, IQR 2.9-17.6 months). The median duration of follow-up was 5.3 years (IQR 2.9-7.5 years). Thirty-five (35%) patients were on mechanical ventilatory support before aortopexy. Twenty-seven (77%) patients could be safely weaned from ventilator support during the same admission after aortopexy (median 2 days, IQR 0-3 days). Fourteen patients required reintervention. Overall mortality was 16%. Multivariable analysis revealed preoperative ventilation (P = 0.004) and bronchial involvement (P = 0.004) to be adverse predictors of survival. Only bronchial involvement was a predictor for reintervention (P = 0.012). CONCLUSIONS Aortopexy appears to be an effective procedure in the treatment of children with severe airway malacia. Bronchial involvement is associated with adverse outcome, and other procedures could be more suitable. For the treatment of severe airway malacia with isolated airway compression, we currently recommend aortopexy to be considered

Haemodynamic performance of 16–20-mm extracardiac Goretex conduits in adolescent Fontan patients at rest and during simulated exercise

OBJECTIVES: To date, it is not known if 16–20-mm extracardiac conduits are outgrown during somatic growth from childhood to adolescence. This study aims to determine total cavopulmonary connection (TCPC) haemodynamics in adolescent Fontan patients at rest and during simulated exercise and to assess the relationship between conduit size and haemodynamics. METHODS: Patient-specific, magnetic resonance imaging-based computational fluid dynamic models of the TCPC were performed in 51 extracardiac Fontan patients with 16–20-mm conduits. Power loss, pressure gradient and normalized resistance were quantified in rest and during simulated exercise. The cross-sectional area (CSA) (mean and minimum) of the vessels of the TCPC was determined and normalized for flow rate (mm2/l/min). Peak (predicted) oxygen uptake was assessed. RESULTS: The median age was 16.2 years (Q1–Q3 14.0–18.2). The normalized mean conduit CSA was 35–73% smaller compared to the inferior and superior vena cava, hepatic veins and left/right pulmonary artery (all P &lt; 0.001). The median TCPC pressure gradient was 0.7 mmHg (Q1–Q3 0.5–0.8) and 2.0 (Q1–Q3 1.4–2.6) during rest and simulated exercise, respectively. A moderate–strong inverse nonlinear relationship was present between normalized mean conduit CSA and TCPC haemodynamics in rest and exercise. TCPC pressure gradients of &gt;_1.0 at rest and &gt;_3.0 mmHg during simulated exercise were observed in patients with a conduit CSA &lt;_ 45 mm2/l/min and favourable haemodynamics (&lt;1 mmHg during both rest and exercise) in conduits &gt;_125 mm2/l/min. Normalized TCPC resistance correlated with (predicted) peak oxygen uptake. CONCLUSIONS: Extracardiac conduits of 16–20 mm have become relatively undersized in most adolescent Fontan patients leading to suboptimal haemodynamics.</p

Noninvasive Advanced Cardiovascular Magnetic Resonance–Derived Fontan Hemodynamics Are Associated With Reduced Kidney Function But Not Albuminuria

Background Kidney disease is the most important predictor of death in patients with a Fontan circulation, yet its clinical and hemodynamic correlates have not been well established. Methods and Results A total of 53 ambulatory patients with a Fontan circulation (median age, 16.2 years, 52.8% male patients) underwent advanced cardiovascular magnetic resonance assessment, including 4‐dimensional flow imaging and computational fluid dynamics. Estimated glomerular filtration rate (eGFR) 3 mg/mmol in 39.6%. The average eGFR decline rate was −1.83 mL/min per 1.73 m2 per year (95% CI, −2.67 to −0.99; P<0.001). Lower eGFR was associated with older age, larger body surface area at examination, longer time since Fontan procedure, and lower systemic ventricular ejection fraction. Higher albumin‐to‐creatinine ratio was associated with absence of fenestration at the Fontan operation, and older age and lower systemic ventricular ejection fraction at the assessment. Lower cross‐sectional area of the Fontan conduit indexed to flow (r=0.32, P=0.038), higher inferior vena cava–conduit velocity mismatch factor (r=−0.35, P=0.022), higher kinetic energy indexed to flow in the total cavopulmonary connection (r=−0.59, P=0.005), and higher total cavopulmonary connection resistance (r=−0.42, P=0.005 at rest; r=−0.43, P=0.004 during exercise) were all associated with lower eGFR but not with albuminuria. Conclusions Kidney dysfunction and albuminuria are common among clinically well adolescents and young adults with a Fontan circulation. Advanced cardiovascular magnetic resonance–derived metrics indicative of declining Fontan hemodynamics are associated with eGFR and might serve as targets to improve kidney health. Albuminuria might be driven by other factors that need further investigation

Aortopexy for the treatment of tracheobronchomalacia in 100 children: a 10-year single-centre experience

OBJECTIVES Our study describes and analyses the results from aortopexy for the treatment of airway malacia in children. METHODS Demographic data, characteristics and preoperative, operative and outcome details, including the need for reintervention, were collected for children undergoing aortopexy between 2006 and 2016. RESULTS One hundred patients [median age 8.2 months, interquartile range (IQR) 3.3-26.0 months] underwent aortopexy. Sixty-four (64%) patients had tracheomalacia (TM) only, 24 (24%) patients had TM extending into their bronchus (tracheobronchomalacia) and 11 (11%) patients had bronchomalacia. Forty-one (41%) children had gastro-oesophageal reflux disease, of which 17 (41%) children underwent a Nissen fundoplication. Twenty-eight (28%) children underwent a tracheo-oesophageal fistula repair prior to aortopexy (median 5.7 months, IQR 2.9-17.6 months). The median duration of follow-up was 5.3 years (IQR 2.9-7.5 years). Thirty-five (35%) patients were on mechanical ventilatory support before aortopexy. Twenty-seven (77%) patients could be safely weaned from ventilator support during the same admission after aortopexy (median 2 days, IQR 0-3 days). Fourteen patients required reintervention. Overall mortality was 16%. Multivariable analysis revealed preoperative ventilation (P = 0.004) and bronchial involvement (P = 0.004) to be adverse predictors of survival. Only bronchial involvement was a predictor for reintervention (P = 0.012). CONCLUSIONS Aortopexy appears to be an effective procedure in the treatment of children with severe airway malacia. Bronchial involvement is associated with adverse outcome, and other procedures could be more suitable. For the treatment of severe airway malacia with isolated airway compression, we currently recommend aortopexy to be considered

Extracardiac conduit adequacy along the respiratory cycle in adolescent Fontan patients

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 &lt; 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 &lt; 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. ChemE/Transport Phenomen