Skip main navigation

How to Image the Adult Patient With Fontan Circulation

Originally publishedhttps://doi.org/10.1161/CIRCIMAGING.116.004273Circulation: Cardiovascular Imaging. 2017;10:e004273

    Clinical Vignette

    A 32-year-old woman was seen for acute chest pain radiating to the neck and arms. The paramedical team witnessed her cardiac arrest on arrival and successfully defibrillated ventricular fibrillation by a single shock. After a stable transfer to the local hospital, she had a second witnessed arrest necessitating further defibrillation. History revealed good functional capacity and no other cardiac symptoms. Examination showed clear lungs, normal heart sounds, a normal abdomen, a blood pressure of 110/79 mm Hg, and an oxygen saturation of 100% (Figure I in the Data Supplement). The ECG showed signs of inferolateral infarction. Cardiac troponin I was 1.06 ng/mL. Telemetry confirmed intermittent nonsustained ventricular tachycardia and sinus bradycardia. Her medical therapy included bisoprolol 2.5 mg and warfarin (International Standardized Ratio, 1.7). Because of tricuspid atresia, transposition of the great arteries, pulmonary stenosis, and ventricular septum defect, she had undergone superior cavo-pulmonary shunt (Glenn) aged 4 years and atrio-pulmonary (Fontan) connection aged 7 years. Three years before, recurrent supraventricular tachycardia necessitated multiple electrophysiological studies, with ablation of focal right atrial tachycardias and cavo-tricuspid isthmus-dependent flutter.

    Echocardiography showed preserved ventricular function, mild flow acceleration across the subaortic ventricular septum defect, mild mitral regurgitation, as well as dilated systemic and hepatic veins (Movies V and VI in the Data Supplement). Computed tomography (CT) of the pulmonary arteries (PA; computed tomography pulmonary angiogram) was subsequently performed, reporting a large opacification defect in the proximal left PA, suggestive of pulmonary embolism (Figure 1). Cardiac magnetic resonance imaging (CMR) thereafter showed a patent Fontan pathway, no thrombi, and normal pulmonary arborization. The coronary sinus, the right atrial, the cardiac, hepatic, and the systemic veins were severely distended (inferior vena cava; Figures 2 and 3; Movies I-III in the Data Supplement), with diastolic flow reversal in the inferior vena cava. No systemic-to-pulmonary collaterals (SPC) were identified. Pulmonary venous return was normal. Left ventricular ejection fraction was 50%. Focal hypokinesia of the lateral and inferolateral segments with late subendocardial gadolinium enhancement were present (Figures 4 and 5; Movie IV in the Data Supplement). A large circumflex artery was seen, arising from the noncoronary sinus, whereas the right coronary artery was reported as nondeveloped. A catheter study subsequently showed a pressure of 10 mm Hg in the Fontan circuit, confirmed this coronary anatomy, and ruled out any obstructions (Figures 6 and 7 Movie VII in the Data Supplement). Serial electrocardiograms showed the typical progression of acute myocardial infarction.

    Figure 1.

    Figure 1. Computer tomography pulmonary angiography showing an opacification defects in the left pulmonary artery (arrow).

    Figure 2.

    Figure 2. Three-dimensional reconstruction from magnetic resonance angiography showing severe dilatation of the cardiac veins and coronary sinus (asterisks).

    Figure 3.

    Figure 3. Sagittal image from b-SSFP cine (cardiac magnetic resonance imaging [CMR]) showing a grossly dilated right atrial (RA) and sluggish flow in the atrio-pulmonary segment (asterisks).

    Figure 4.

    Figure 4. Short-axis image (cardiac magnetic resonance imaging [CMR]) showing late gadolinium enhancement in the left ventricular (LV) inferolateral wall (arrow).

    Figure 5.

    Figure 5. Long-axis image (cardiac magnetic resonance imaging [CMR]) showing late gadolinium enhancement of the left ventricular (LV) inferolateral wall (arrows).

    Figure 6.

    Figure 6. Hemodynamic measures of the presented patient. IVC indicates inferior vena cava; LPA, left pulmonary artery; LPV, left pulmonary veins; LVEDP, left ventricular end-diastolic pressure; PA, pulmonary artery; RPA, right pulmonary artery; RPV, right pulmonary veins; and SVC, superior vena cava.

    Figure 7.

    Figure 7. Right anterior oblique projection from coronary angiography showing a large circumflex artery (arrow) with obtuse marginal branches, arising from the noncoronary sinus.

    The Fontan Circulation: Principle and Pitfalls

    The Fontan procedure is a well-established surgical approach to improve survival in univentricular heart disease, rerouting systemic venous blood flow directly to the lungs in a multistaged approach. Passive pulmonary blood flow is driven by a transpulmonary pressure gradient, thus, bypassing the heart to offload the ventricle. The original technique proposed anastomosing the right atrial appendage to the PA. Several modifications have led to the contemporary total cavo-pulmonary connection since.1 Long-term complications are frequent (Table 1). Although some represent potentially treatable complications, a significant proportion of patients undergo hemodynamic deterioration even in their absence. This may result in Fontan Failure, a state characterized by multiorgan dysfunction, peripheral edema, ascites, and abnormal protein turnover. Its pathogenesis is still incompletely understood. Once established, the outcome is poor and heart transplant is the only recognized cure. Early diagnosis and transplant listing are crucial to survival. Routine imaging is, therefore, paramount in the follow-up of Fontan patients.

    Table 1. Complications of the Fontan Circulation and Proposed Imaging Approach

    ComplicationPossible CausesPossible Imaging Modalities
    Obstruction of the venous-to-pulmonary pathwayThromboembolism, external compression (eg, dilated atria), traction/torsion (eg, after shunt)Echocardiography, CMR, CT, catheter study: direct visualization of obstruction or signs of upstream dilatation; pressure gradient (catheter)
    AV valve regurgitationVentricular dilatation, congenital dysplasiaEchocardiography, CMR, catheter, (CT): direct visualization of regurgitant jet; estimation of regurgitant fraction (CMR)
    Outlet obstruction(Sub-) valvar obstruction, VSD restriction, (neo) aortic obstructionEchocardiography, CMR, CT, catheter study: direct visualization; estimation of pressure gradient (catheter and echocardiography)
    Systolic dysfunctionSystemic RV, decreased preload, increased afterload, poor coronary perfusion pressureCMR, echocardiography (CT, catheter): volume measurement and calculation of ejection fraction
    Diastolic dysfunctionVolume overload (eg, shunt in early stages; high collateral flow), ventricular hypertrophyCatheter study: direct pressure measurement (consider fluid challenge)
    Echocardiography: tissue deformation indices (longitudinal follow-up)
    Hybrid CMR under dobutamine stress
    Increased pulmonary vascular resistanceChronic high QP in early stages; disproportionate growth of pulmonary vasculatureCatheter study and hybrid CMR: direct pressure measurement and calculation of pulmonary vascular resistance
    Collateral flowVenous decompression, lack of hepatic venous flow to lungs, chronic cyanosisCMR, catheter study, (CT): direct visualization of collateral vessels and collateral flow estimation
    Echocardiography: indirect visualization of veno-venous collaterals by contrast injection
    Liver disease (cirrhosis, neoplasia)Chronic hepatic venous congestionTransient/MR Elastography
    Liver ultrasound, CT, MR

    AV indicates atrioventricular; CMR, cardiac magnetic resonance imaging; CT, computed tomography; MR, magnetic resonance; RV, right ventricle; and VSD, ventricular septum defect.

    How to Use Imaging in the Pathological Fontan Circulation

    A full echocardiographic study should be part of every outpatient visit in intervals of no >12 months (Table 2). Functional assessment remains challenging, especially in the systemic RV, but serial imaging can reveal deterioration over time using M-mode, tissue Doppler, or fractional area change. Mitral inflow velocities can reveal abnormal diastolic function (Figure 8). Other techniques for functional assessment have been described.2,3

    Table 2. Echocardiography in Fontan Imaging

    Strengths
     Availability, low cost, relative ease of use, bedside compatibility
     Lack of invasiveness and ionizing radiation, no contraindications
     High temporal and spatial resolution
     Relatively robust to arrhythmia
     Good characterization of valve function
    Weaknesses
     Inter- and intraobserver variability
     Oftentimes poor acoustic window secondary to surgery
     No myocardial tissue characterization
     Limited use for assessment of ventricular volume and function, especially in the systemic RV
     Unsuitable for shunt estimation and visualization of collaterals
     Certain structures may be difficult to visualize (pulmonary veins, conduit)

    RV indicates right ventricle.

    Figure 8.

    Figure 8. Pulsed wave Doppler signal across the mitral valve, indicating abnormal diastolic function.

    The advantages of CMR are widely recognized (Table 3).4 Vascular anatomy can be imaged with high spatial detail, even in the presence of metal, poor breath holding, or slow blood flow.47 Gadolinium-contrast application is recommended for increased tissue contrast, better delineation of vascular anatomy and shunts, as well as tissue viability assessment. We have recently demonstrated the usefulness of time-resolved contrast-enhanced imaging in children and adults with congenital heart disease, where contrast passage can be visualized throughout the entire cardiac cycle, even in free breathing.8 This offers additional diagnostic information that could point toward collateral flow or flow obstacles and obviates the need for timing in the acquisition of data. Volumetric and functional analysis of the ventricle is typically achieved by stacked cine imaging in the short axis (eg, 2 dimensional balanced steady state free precession).5,9 Different techniques of image planning and postprocessing have been described and should be consistent within an institution to keep interobserver variability low and, thus, accurately detect changes in volumes and function over time.5 This is crucial because end-diastolic volume is a strong predictor of death and transplant-free survival.10 For flow measurement, real-time phase-encoding velocity mapping sequences are more accurate than breath-held phase-contrast imaging techniques because of the effects of breath holding on passive pulmonary filling.11 However, because of the limited availability of these sequences, retrospectively gated phase-contrast CMR in free breathing is commonly regarded standard by most centers. Calculating the difference between pulmonary venous return and PA flow is the most accurate way to determine systemic-to-pulmonary collateral flow.12 Phase-contrast imaging of the systemic outlet also allows for quantification of semilunar valve regurgitation and can be useful for the quality control of ventricular measurements by comparing stroke volumes from both methods. Total venous flow return is a known CMR biomarker of Fontan decompensation. However, its role in the early diagnosis of hemodynamic failure has yet to be evaluated.13

    Table 3. Magnetic Resonance in Fontan Imaging

    Strengths
     Comprehensive imaging of virtually any structure, independently of user and anatomic problems
     3D imaging
     Lack of invasiveness and ionizing radiation
     High spatial resolution
     Tissue characterization
     Gold standard for volumetry and functional assessment
     Shunt estimation
    Weaknesses
     Expensive, lengthy examination technique, requires patient cooperation; unsuitable for acute setting
     Limited availability, reserved to expert centers
     Postprocessing
     Limited temporal resolution
     Some sequences vulnerable to arrhythmia
     No pressure measurement
     Contraindications apply (metal, pregnancy, claustrophobia)
    Pitfalls
     Upper limb contrast injection can mimic pulmonary embolus
     Sluggish, swirling blood flow may cause image artifacts mimicking thrombus (Figure II in the Data Supplement)

    3D indicates 3 dimensional.

    CT is an excellent alternative to CMR as it allows for a comprehensive assessment of anatomy at submillimeter isotropic resolution, cardiac and valvar function, as well as of stent patency (Table 4).14 Short scanning times make this imaging modality ideal for acute situations where information needs to be acquired quickly with minimal preparatory effort and little patient cooperativeness. Cardiac CT is also the best available technique for imaging metallic intravascular stents and devices within the Fontan circulation. However, temporal resolution is poor compared with that of CMR and echocardiography, and its association with ionizing radiation, albeit low on modern systems, limit its routine use. Therefore, CT should be restricted to cases where CMR is either unavailable or unsafe to perform and where additional information, such as stent or shunt patency, must be obtained.

    Table 4. Computed Tomography in Fontan Imaging

    Strengths
     Good availability, short scan duration, suitable for acute work-up
     Comprehensive, user-independent imaging of virtually any structure
     3D imaging
     Noninvasive
     Gold-standard for stent assessment
     Very high spatial resolution
     Good coronary imaging
     Suitable for volumetry and functional assessment
    Weaknesses
     Exposition to ionizing radiation (albeit low on modern systems)
     Poor tissue contrast
     Low temporal resolution
     Limited hemodynamic data
     Limited use in valve assessment
    Pitfalls
     Upper limb contrast injection can mimic pulmonary embolus

    3D indicates 3 dimensional.

    The importance of invasive imaging by cardiac catheterization has declined substantially with the increased availability of CMR and CT. Because of its association with ionizing radiation and procedural risk, the indication for invasive, catheter-based imaging is of limited use for routine imaging (Table 5). Moreover, in patients with previous cardiac surgery, vascular access can be difficult to obtain. Therefore, invasive catheter studies should be reserved to cases where noninvasive options have been exhausted. Hybrid CMR-augmented cardiac catheterization can assess pulmonary vascular resistance prior to cardiac transplantation.15

    Table 5. Cardiac Catheter Studies in Fontan Imaging

    Strengths
     Possibility to intervene
     Very high spatial and temporal resolution
     Suitable for stent imaging
     Pressure and flow measurement
     3D reconstruction on modern systems (albeit limited)
     Good coronary imaging
    Weaknesses
     Exposition to ionizing radiation
     Invasive
     May require anesthesia or sedation
     Contrast-associated nephrotoxicity
     Vascular access may be difficult after repeat cardiac surgery

    3D indicates 3 dimensional.

    Challenges and Advances in Fontan Imaging

    Diastolic dysfunction is a key issue in univentricular congenital heart disease, and noninvasive diagnosis remains a challenge (Table 1). Echocardiographic tissue deformation indices do not typically comply with normal values from biventricular hearts but may reveal progressive dysfunction over time. Recently, hemodynamic stress protocols using dobutamine or fluid boluses have been demonstrated to detect latent diastolic dysfunction by CMR or cardiac catheter.16,17

    The dual cavo-pulmonary blood supply often results in preferential streaming from the superior vena cava to the right PA and from the inferior vena cava to the left PA. This may lead to several problems. Incomplete opacification of 1 branch PA after contrast application can mimic pulmonary embolism—as was the case in this patient (Figure 2). This can be overcome by injecting contrast into the right arm, the lower extremity, or both, depending on the clinical question. Moreover, preferential blood supply from the lower body to 1 lung is known to promote arteriovenous malformations in the contralateral lung because of the lack of hepatic venous return. Phase-velocity CMR in a perpendicular plane relative to the branch PAs has been shown to be more accurate than perfusion scintigraphy for the measurement of differential lung perfusion.18 More recently, time-resolved 4-dimensional-flow CMR sequences have emerged as a novel approach for surgical planning and risk stratification.19 Although typically longer to acquire than conventional 2-dimensional flow-mapping sequences, their advantage lies in the possibility to obtain all flow-encoded information within a defined volume along all spatial directions as a single data set and to arbitrarily define the plane of flow measurement in retrospect. Flow patterns can, thus, be visualized multidimensionally and interpreted in conjunction with anatomy.20 Similarly, though technically different, computational fluid dynamics are increasingly used to assess the interactions between blood flow and anatomic structures.21

    Finally, liver cirrhosis and hepatic neoplasia are increasingly recognized sequelae of the Fontan circulation and can worsen prognosis.22 Screening for cirrhosis by magnetic resonance elastography offers several advantages over conventional, ultrasound-based techniques.23 Regular screening for structural abnormalities of the liver using ultrasound, magnetic resonance, or CT is considered standard.22

    Approach to the Presented Patient

    Our patient presented with life-threatening arrhythmia, and therefore, several potentially deleterious and reversible differential diagnoses had to be rapidly eliminated. Pulmonary thromboembolism was initially suspected because of subtherapeutic anticoagulation and poor blood flow in the Fontan pathway, supported by an opacification defect in the left PA. However, this was subsequently demonstrated to be caused by preferential pulmonary blood streaming, and CMR revealed evidence of poor function of the Fontan circuit and myocardial infarction. No coronary artery anomalies were detected, which raises the possibility of spasm or thromboembolism. Abnormal hemodynamics, including chronically reduced coronary perfusion pressures with possible atrial arrhythmia, may have contributed to the infarction. Moreover, it is conceivable that sluggish drainage from the cardiac veins may have precipitated thrombus formation and caused venous myocardial infarction. Such a thrombus may have spontaneously migrated into the pulmonary vascular bed and dissolved under anticoagulation therapy. An implantable cardioverter-defibrillator was implanted to prevent sudden death as per current guidelines.24 Transvenous leads are difficult to position in the Fontan circuit, and therefore, a subcutaneous system was used.

    Early recognition of the Failing Fontan physiology remains challenging. In the presented case, no lesion amenable to treatment was found to potentially improve hemodynamics. Though Fontan pressure was acceptable, this finding must be interpreted in the context of procedural anesthesia. The presence of atrio-pulmonary-type Fontan is a known risk factor for deteriorating hemodynamics because it causes energy loss, dilatation and, thus, poor flow in the circuit.25 This, in combination with her history of intractable arrhythmia and myocardial infarction, puts the patient at high risk of death, irrespective of her preserved ejection fraction and good functional status.2527 Because timely listing is crucial, our patient was, therefore, subsequently referred for heart transplant evaluation.

    In summary, complex and univentricular congenital heart disease is a growing disease entity in the adult population and necessitates rigorous longitudinal monitoring to identify patients at risk. Appropriate imaging protocols for the chronic and acute management of this patient group are essential, and different modalities should be used in a complementary fashion to assess hemodynamics, anatomy, and prognosis. Early recognition of failing hemodynamics in Fontan patients is essential to secure long-term survival.

    Footnotes

    The Data Supplement is available at http://circimaging.ahajournals.org/lookup/suppl/doi:10.1161/CIRCIMAGING.116.004273/-/DC1.

    Correspondence to Jakob Hauser, UCL Centre for Cardiovascular Imaging, 30 Guilford St, WC1N 1EH London, UK. E-mail

    References

    • 1. AboulHosn JA, Shavelle DM, Castellon Y, Criley JM, Plunkett M, Pelikan P, Dinh H, Child JS. Fontan operation and the single ventricle.Congenit Heart Dis. 2007; 2:2–11. doi: 10.1111/j.1747-0803.2007.00065.x.CrossrefMedlineGoogle Scholar
    • 2. Tei C, Ling LH, Hodge DO, Bailey KR, Oh JK, Rodeheffer RJ, Tajik AJ, Seward JB. New index of combined systolic and diastolic myocardial performance: a simple and reproducible measure of cardiac function–a study in normals and dilated cardiomyopathy.J Cardiol. 1995; 26:357–366.MedlineGoogle Scholar
    • 3. Friedberg MK, Silverman NH. The systolic to diastolic duration ratio in children with hypoplastic left heart syndrome: a novel Doppler index of right ventricular function.J Am Soc Echocardiogr. 2007; 20:749–755. doi: 10.1016/j.echo.2006.11.014.CrossrefMedlineGoogle Scholar
    • 4. Lewis G, Thorne S, Clift P, Holloway B. Cross-sectional imaging of the Fontan circuit in adult congenital heart disease.Clin Radiol. 2015; 70:667–675. doi: 10.1016/j.crad.2015.02.011.CrossrefMedlineGoogle Scholar
    • 5. Fratz S, Chung T, Greil GF, Samyn MM, Taylor AM, Valsangiacomo Buechel ER, Yoo SJ, Powell AJ. Guidelines and protocols for cardiovascular magnetic resonance in children and adults with congenital heart disease: SCMR expert consensus group on congenital heart disease.J Cardiovasc Magn Reson. 2013; 15:51. doi: 10.1186/1532-429X-15-51.CrossrefMedlineGoogle Scholar
    • 6. Grewal J, Al Hussein M, Feldstein J, Kiess M, Ellis J, Human D, Leipsic J. Evaluation of silent thrombus after the Fontan operation.Congenit Heart Dis. 2013; 8:40–47. doi: 10.1111/j.1747-0803.2012.00699.x.CrossrefMedlineGoogle Scholar
    • 7. Nordmeyer J, Gaudin R, Tann OR, Lurz PC, Bonhoeffer P, Taylor AM, Muthurangu V. MRI may be sufficient for noninvasive assessment of great vessel stents: an in vitro comparison of MRI, CT, and conventional angiography.AJR Am J Roentgenol. 2010; 195:865–871. doi: 10.2214/AJR.09.4166.CrossrefMedlineGoogle Scholar
    • 8. Steeden JA, Pandya B, Tann O, Muthurangu V. Free breathing contrast-enhanced time-resolved magnetic resonance angiography in pediatric and adult congenital heart disease.J Cardiovasc Magn Reson. 2015; 17:38. doi: 10.1186/s12968-015-0138-9.CrossrefMedlineGoogle Scholar
    • 9. Plein S, Bloomer TN, Ridgway JP, Jones TR, Bainbridge GJ, Sivananthan MU. Steady-state free precession magnetic resonance imaging of the heart: comparison with segmented k-space gradient-echo imaging.J Magn Reson Imaging. 2001; 14:230–236.CrossrefMedlineGoogle Scholar
    • 10. Rathod RH, Prakash A, Kim YY, Germanakis IE, Powell AJ, Gauvreau K, Geva T. Cardiac magnetic resonance parameters predict transplantation-free survival in patients with fontan circulation.Circ Cardiovasc Imaging. 2014; 7:502–509. doi: 10.1161/CIRCIMAGING.113.001473.LinkGoogle Scholar
    • 11. Körperich H, Barth P, Gieseke J, Müller K, Burchert W, Esdorn H, Kececioglu D, Beerbaum P, Laser KT. Impact of respiration on stroke volumes in paediatric controls and in patients after Fontan procedure assessed by MR real-time phase-velocity mapping.Eur Heart J Cardiovasc Imaging. 2015; 16:198–209. doi: 10.1093/ehjci/jeu179.CrossrefMedlineGoogle Scholar
    • 12. Odenwald T, Quail MA, Giardini A, Khambadkone S, Hughes M, Tann O, Hsia TY, Muthurangu V, Taylor AM. Systemic to pulmonary collateral blood flow influences early outcomes following the total cavopulmonary connection.Heart. 2012; 98:934–940. doi: 10.1136/heartjnl-2011-301599.CrossrefMedlineGoogle Scholar
    • 13. Ovroutski S, Nordmeyer S, Miera O, Ewert P, Klimes K, Kühne T, Berger F. Caval flow reflects Fontan hemodynamics: quantification by magnetic resonance imaging.Clin Res Cardiol. 2012; 101:133–138. doi: 10.1007/s00392-011-0374-4.CrossrefMedlineGoogle Scholar
    • 14. Han BK, Rigsby CK, Hlavacek A, Leipsic J, Nicol ED, Siegel MJ, Bardo D, Abbara S, Ghoshhajra B, Lesser JR, Raman S, Crean AM; Society of Cardivascular Computed Tomography; Society of Pediatric Radiology; North American Society of Cardiac Imaging. Computed Tomography Imaging in Patients with Congenital Heart Disease Part I: Rationale and Utility. An Expert Consensus Document of the Society of Cardiovascular Computed Tomography (SCCT): Endorsed by the Society of Pediatric Radiology (SPR) and the North American Society of Cardiac Imaging (NASCI).J Cardiovasc Comput Tomogr. 2015; 9:475–92. doi: 10.1016/j.jcct.2015.07.004.CrossrefMedlineGoogle Scholar
    • 15. Pushparajah K, Tzifa A, Bell A, Wong JK, Hussain T, Valverde I, Bellsham-Revell HR, Greil G, Simpson JM, Schaeffter T, Razavi R. Cardiovascular magnetic resonance catheterization derived pulmonary vascular resistance and medium-term outcomes in congenital heart disease.J Cardiovasc Magn Reson. 2015; 17:28. doi: 10.1186/s12968-015-0130-4.CrossrefMedlineGoogle Scholar
    • 16. Averin K, Hirsch R, Seckeler MD, Whiteside W, Beekman RH, Goldstein BH. Diagnosis of occult diastolic dysfunction late after the Fontan procedure using a rapid volume expansion technique.Heart. 2016; 102:1109–1114. doi: 10.1136/heartjnl-2015-309042.CrossrefMedlineGoogle Scholar
    • 17. Schmitt B, Steendijk P, Ovroutski S, Lunze K, Rahmanzadeh P, Maarouf N, Ewert P, Berger F, Kuehne T. Pulmonary vascular resistance, collateral flow, and ventricular function in patients with a Fontan circulation at rest and during dobutamine stress.Circ Cardiovasc Imaging. 2010; 3:623–631. doi: 10.1161/CIRCIMAGING.109.931592.LinkGoogle Scholar
    • 18. Fratz S, Hess J, Schwaiger M, Martinoff S, Stern HC. More accurate quantification of pulmonary blood flow by magnetic resonance imaging than by lung perfusion scintigraphy in patients with fontan circulation.Circulation. 2002; 106:1510–1513.LinkGoogle Scholar
    • 19. Bächler P, Valverde I, Pinochet N, Nordmeyer S, Kuehne T, Crelier G, Tejos C, Irarrazaval P, Beerbaum P, Uribe S. Caval blood flow distribution in patients with Fontan circulation: quantification by using particle traces from 4D flow MR imaging.Radiology. 2013; 267:67–75. doi: 10.1148/radiol.12120778.CrossrefMedlineGoogle Scholar
    • 20. Markl M, Kilner PJ, Ebbers T. Comprehensive 4D velocity mapping of the heart and great vessels by cardiovascular magnetic resonance.J Cardiovasc Magn Reson. 2011; 13:7. doi: 10.1186/1532-429X-13-7.CrossrefMedlineGoogle Scholar
    • 21. Pennati G, Corsini C, Hsia TY, Migliavacca F; Modeling of Congenital Hearts Alliance (MOCHA) Investigators. Computational fluid dynamics models and congenital heart diseases.Front Pediatr. 2013; 1:4. doi: 10.3389/fped.2013.00004.CrossrefMedlineGoogle Scholar
    • 22. Greenway SC, Crossland DS, Hudson M, Martin SR, Myers RP, Prieur T, Hasan A, Kirk R. Fontan-associated liver disease: Implications for heart transplantation.J Heart Lung Transplant. 2016; 35:26–33. doi: 10.1016/j.healun.2015.10.015.CrossrefMedlineGoogle Scholar
    • 23. Venkatesh SK, Ehman RL. Magnetic resonance elastography of liver.Magn Reson Imaging Clin N Am. 2014; 22:433–446. doi: 10.1016/j.mric.2014.05.001.CrossrefMedlineGoogle Scholar
    • 24. Priori SG, Blomström-Lundqvist C, Mazzanti A, Blom N, Borggrefe M, Camm J, Elliott PM, Fitzsimons D, Hatala R, Hindricks G, Kirchhof P, Kjeldsen K, Kuck KH, Hernandez-Madrid A, Nikolaou N, Norekvål TM, Spaulding C, Van Veldhuisen DJ. 2015 ESC Guidelines for the management of patients with ventricular arrhythmias and the prevention of sudden cardiac death: The Task Force for the Management of Patients with Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death of the European Society of Cardiology (ESC). Endorsed by: Association for European Paediatric and Congenital Cardiology (AEPC).Eur Heart J. 2015; 36:2793–2867. doi: 10.1093/eurheartj/ehv316.CrossrefMedlineGoogle Scholar
    • 25. Diller GP, Giardini A, Dimopoulos K, Gargiulo G, Müller J, Derrick G, Giannakoulas G, Khambadkone S, Lammers AE, Picchio FM, Gatzoulis MA, Hager A. Predictors of morbidity and mortality in contemporary Fontan patients: results from a multicenter study including cardiopulmonary exercise testing in 321 patients.Eur Heart J. 2010; 31:3073–3083. doi: 10.1093/eurheartj/ehq356.CrossrefMedlineGoogle Scholar
    • 26. Griffiths ER, Kaza AK, Wyler von Ballmoos MC, Loyola H, Valente AM, Blume ED, del Nido P. Evaluating failing Fontans for heart transplantation: predictors of death.Ann Thorac Surg. 2009; 88:558–563; discussion 563–4. doi: 10.1016/j.athoracsur.2009.03.085.CrossrefMedlineGoogle Scholar
    • 27. Khairy P, Fernandes SM, Mayer JE, Triedman JK, Walsh EP, Lock JE, Landzberg MJ. Long-term survival, modes of death, and predictors of mortality in patients with Fontan surgery.Circulation. 2008; 117:85–92. doi: 10.1161/CIRCULATIONAHA.107.738559.LinkGoogle Scholar