Thromboembolism and the role of anticoagulation in the Fontan patient

Biomechanical Analysis of Age-Dependent Changes in Fontan Power Loss

The hemodynamics in Fontan patients with single ventricles rely on favorable flow and energetics, especially in the absence of a subpulmonary ventricle. Age-related changes in energetics for extracardiac and lateral tunnel Fontan procedures are not well understood. Vorticity (VOR) and viscous dissipation rate (VDR) are two descriptors that can provide insights into flow dynamics and dissipative areas in Fontan pathways, potentially contributing to power loss. This study examined power loss and its correlation with spatio-temporal flow descriptors (vorticity and VDR). Data from 414 Fontan patients were used to establish a relationship between the superior vena cava (SVC) to inferior vena cava (IVC) flow ratio and age. Computational flow modeling was conducted for both extracardiac conduits (ECC, n = 16) and lateral tunnels (LT, n = 25) at different caval inflow ratios of 2, 1, and 0.5 that corresponded with ages 3, 8, and 15+. In both cohorts, vorticity and VDR correlated well with PL, but ECC cohort exhibited a slightly stronger correlation for PL-VOR (>0.83) and PL-VDR (>0.89) than that for LT cohort (>0.76 and > 0.77, respectively) at all ages. Our data also suggested that absolute and indexed PL increase (p < 0.02) non-linearly as caval inflow changes with age and are highly patient-specific. Comparison of indexed power loss between our ECC and LT cohort showed that while ECC had a slightly higher median PL for all 3 caval inflow ratio examined (3.3, 8.3, 15.3) as opposed to (2.7, 7.6, 14.8), these differences were statistically non-significant. Lastly, there was a consistent rise in pressure gradient across the TCPC with age-related increase in IVC flows for both ECC and LT Fontan patient cohort. Our study provided hemodynamic insights into Fontan energetics and how they are impacted by age-dependent change in caval inflow. This workflow may help assess the long-term sustainability of the Fontan circulation and inform the design of more efficient Fontan conduits.

Detection of occult thrombosis in individuals with Fontan circulation by cardiac MRI

OBJECTIVE

Identifying thrombus formation in Fontan circulation has been highly variable, with reports between 17 and 33%. Initially, thrombus detection was mainly done through echocardiograms. Delayed-enhancement cardiac MRI is emerging as a more effective imaging technique for thrombus identification. This study aims to determine the prevalence of occult cardiac thrombosis in patients undergoing clinically indicated cardiac MRI.

METHODS

A retrospective chart review of children and adults in the Duke University Hospital Fontan registry who underwent delayed-enhancement cardiac MRI. Individuals were excluded if they never received a delayed-enhancement cardiac MRI or had insufficient data. Demographic characteristics, native heart anatomy, cardiac MRI measurements, and thromboembolic events were collected for all patients.

RESULTS

In total, 119 unique individuals met inclusion criteria with a total of 171 scans. The median age at Fontan procedure was 3 (interquartile range 1, 4) years. The majority of patients had dominant systemic right ventricle. Cardiac function was relatively unchanged from the first cardiac MRI to the third cardiac MRI. While 36.4% had a thrombotic event by history, only 0.5% (1 patient) had an intracardiac thrombus detected by delayed-enhancement cardiac MRI.

CONCLUSIONS

Despite previous echocardiographic reports of high prevalence of occult thrombosis in patients with Fontan circulation, we found very low prevalence using delayed-enhancement cardiac MRI. As more individuals are reaching adulthood after requiring early Fontan procedures in childhood, further work is needed to develop thrombus-screening protocols as a part of anticoagulation management.

EASL-ERN position paper on liver involvement in patients with Fontan-type circulation

Fontan-type surgery is the final step in the sequential palliative surgical treatment of infants born with a univentricular heart. The resulting long-term haemodynamic changes promote liver damage, leading to Fontan-associated liver disease (FALD), in virtually all patients with Fontan circulation. Owing to the lack of a uniform definition of FALD and the competitive risk of other complications developed by Fontan patients, the impact of FALD on the prognosis of these patients is currently debatable. However, based on the increasing number of adult Fontan patients and recent research interest, the European Association for The Study of the Liver and the European Reference Network on Rare Liver Diseases thought a position paper timely. The aims of the current paper are: (1) to provide a clear definition and description of FALD, including clinical, analytical, radiological, haemodynamic, and histological features; (2) to facilitate guidance for staging the liver disease; and (3) to provide evidence- and experience-based recommendations for the management of different clinical scenarios.

A Multisite Retrospective Review of Direct Oral Anticoagulants Compared to Warfarin in Adult Fontan Patients

PURPOSE

Direct oral anticoagulants (DOACs) are not recommended in adult Fontan patients (Level of Evidence C). We hypothesized that DOACs are comparable to warfarin and do not increase thrombotic and embolic complications (TEs) or clinically significant bleeds.

METHODS

We reviewed the medical records of adult Fontan patients on DOACs or warfarin at three major medical centers. We identified 130 patients: 48 on DOACs and 107 on warfarin. In total, they were treated for 810 months on DOACs and 5637 months on warfarin.

RESULTS

The incidence of TEs in patients on DOACs compared to those on warfarin was not increased in a statistically significant way (hazard ratio [HR] 1.7 and p value 0.431). Similarly, the incidence of nonmajor and major bleeds in patients on DOACs compared to those on warfarin was also not increased in a statistically significant way (HR for nonmajor bleeds in DOAC patients was 2.8 with a p value of 0.167 and the HR for major bleeds was 2.0 with a p value 0.267). In multivariate analysis, congestive heart failure (CHF) was a risk factor for TEs across both groups (odds ratio [OR] = 4.8, 95% confidence interval [CI] = 1.3-17.6) and bleed history was a risk factor for clinically significant bleeds (OR = 6.8, 95% CI = 2.7-17.2).

CONCLUSION

In this small, retrospective multicenter study, the use of DOACs did not increase the risk of TEs or clinically significant bleeds compared to warfarin in a statistically significant way.

Thromboembolic Complications in Adult Patients Following Fontan Procedure-A Multicenter Study

BACKGROUND

Morbidity and mortality following Fontan (FO) surgery are primarily thromboembolic in nature. However, follow-up data regarding thromboembolic complications (TECs) in adult patients after FO procedure are inconsistent. In this multicenter study, we investigated the incidence of TECs in FO patients.

METHODS

We studied 91 patients who underwent FO procedure. Clinical data, laboratory, and imaging investigations were collected prospectively during the scheduled medical appointments in 3 Adult Congenital Heart Disease Departments in Poland. TECs were recorded during a median follow-up of 31 months.

RESULTS

Four patients (4.4%) were lost to follow-up. The mean age of patients was 25.3 (±6.0) years at enrollment, and the mean time between FO operation and investigation was 22.1 (±5.1) years. A total of 21 out of 91 patients (23.1%) had a history of 24 TECs since an FO procedure, mainly pulmonary embolism (PE; n = 12, 13.2%), including 4 (33.3%) silent PE. The mean time since FO operation to the first TEC was 17.8 (±5.1) years. During follow-up, we documented 9 TECs in 7 (8.0%) patients, mainly PE (n = 5, 5.5%). Most patients with TEC had a left type of systemic ventricle (57.1%). Three patients (42.9%) were treated with aspirin, 3 (3.4%) with Vitamin K antagonists or novel oral anticoagulants, and 1 patient had no antithrombotic treatment at the time of TEC occurrence. Supraventricular tachyarrhythmias were present in 3 patients (42.9%).

CONCLUSIONS

This prospective study shows that TECs are common in FO patients, and a significant number of these events occur during adolescence and young adulthood. We also indicated how much TECs are underestimated in the growing adult FO population. The complexity of the problem requires more studies, especially to standardize the prevention of TECs in the whole FO population.

Cardiac Imaging in Patients After Fontan Palliation: Which Test and When?

The Fontan operation represents the final stage of a series of palliative surgical procedures for children born with complex congenital heart disease, where a "usual" biventricular physiology cannot be restored. The palliation results in the direct connection of the systemic venous returns to the pulmonary arterial circulation without an interposed ventricle. In this unique physiology, systemic venous hypertension and intrathoracic pressures changes due to respiratory mechanics play the main role for propelling blood through the pulmonary vasculature. Although the Fontan operation has dramatically improved survival in patients with a single ventricle congenital heart disease, significant morbidity is still a concern. Patients with Fontan physiology are in fact suffering from a multitude of complications mainly due to the increased systemic venous pressure. Consequently, these patients need close clinical and imaging monitoring, where cardiac exams play a key role. In this article, we review the main cardiac imaging modalities available, summarizing their main strengths and limitations in this peculiar setting. The main purpose is to provide a practical approach for all clinicians involved in the care of these patients, even for those less experienced in cardiac imaging.

Current Treatment Options for the Failing Fontan Circulation

The Fontan operation was introduced in 1968. For congenital malformations, where biventricular repair is unsuitable, the Fontan procedure has provided a long-term palliation strategy with improved outcomes compared to the initially developed procedures. Despite these improvements, several complications merely due to a failing Fontan circulation, including myocardial dysfunction, arrhythmias, increased pulmonary vascular resistance, protein-losing enteropathy, hepatic dysfunction, plastic bronchitis, and thrombo-embolism, may occur, thereby limiting the life-expectancy in this patient cohort. This review provides an overview of the most common complications of Fontan circulation and the currently available treatment options.

Properties of Plasma Clots in Adult Patients Following Fontan Procedure: Relation to Clot Permeability and Lysis Time-Multicenter Study

Objectives: thromboembolic complications are a major cause of morbidity and mortality following Fontan (FO) surgery. It is also well established that altered FO circulation results in systemic complications, including liver and endothelium damage. We sought to evaluate whether dysfunctions of these sources of hemostatic factors may result in changes of fibrin clot properties. Methods: a permeation coefficient (K_s) and clot lysis time (CLT) were assessed in 66 FO patients, aged 23.0 years [IQR 19.3–27.0], and 59 controls, aged 24.0 years [IQR 19.0–29.0]. K_s was determined using a pressure-driven system. CLT value was measured according to assay described by Pieters et al. Endothelium and liver-derived hemostatic factors along with liver function parameters were evaluated. The median time between FO operation and investigation was 20.5 years [IQR 16.3–22.0]. Results: FO patients had lower K_s (p = 0.005) and prolonged CLT (p < 0.001) compared to that of controls. K_s correlated with CLT (r = −0.28), FVIII (r = −0.30), FIX (r = −0.38), fibrinogen (r = −0.41), ALT (r = −0.25), AST (r = −0.26), GGTP (r = −0.27) and vWF antigen (r = −0.30), (all p < 0.05). CLT correlated with the time between FO operation and investigation (r = 0.29) and FIX (r = 0.25), (all p < 0.05). After adjustment for potential cofounders, TAFI antigen and GGTP were independent predictors of reduced K_s (OR 1.041 per 1% increase, 95% CI 1.009–1.081, p = 0.011 and OR 1.025 per 1 U/L increase, 95% CI 1.005–1.053, p = 0.033, respectively). Protein C and LDL cholesterol predicted prolonged CLT (OR 1.078 per 1% increase, 95% CI 1.027–1.153, p = 0.001 and OR 6.360 per 1 μmol/L increase, 95% CI 1.492–39.894, p = 0.011, respectively). Whereas elevated tPA was associated with lower risk of prolonged CLT (OR 0.550 per 1 ng/mL, 95% CI 0.314–0.854, p = 0.004). GGTP correlated positively with time between FO surgery and investigation (r = 0.25, p = 0.045) and patients with abnormal elevated GGTP activity (n = 28, 42.4%) had decreased K_s, compared to that of the others (5.9 × 10⁻⁹ cm² vs. 6.8 × 10⁻⁹ cm², p = 0.042). Conclusion: our study shows that cellular liver damage and endothelial injury were associated with prothrombotic clot phenotype reflected by K_s and CLT.

Bleeding and thrombotic risk in pregnant women with Fontan physiology

BACKGROUND/OBJECTIVES

Pregnancy may potentiate the inherent hypercoagulability of the Fontan circulation, thereby amplifying adverse events. This study sought to evaluate thrombosis and bleeding risk in pregnant women with a Fontan.

METHODS

We performed a retrospective observational cohort study across 13 international centres and recorded data on thrombotic and bleeding events, antithrombotic therapies and pre-pregnancy thrombotic risk factors.

RESULTS

We analysed 84 women with Fontan physiology undergoing 108 pregnancies, average gestation 33±5 weeks. The most common antithrombotic therapy in pregnancy was aspirin (ASA, 47 pregnancies (43.5%)). Heparin (unfractionated (UFH) or low molecular weight (LMWH)) was prescribed in 32 pregnancies (30%) and vitamin K antagonist (VKA) in 10 pregnancies (9%). Three pregnancies were complicated by thrombotic events (2.8%). Thirty-eight pregnancies (35%) were complicated by bleeding, of which 5 (13%) were severe. Most bleeds were obstetric, occurring antepartum (45%) and postpartum (42%). The use of therapeutic heparin (OR 15.6, 95% CI 1.88 to 129, p=0.006), VKA (OR 11.7, 95% CI 1.06 to 130, p=0.032) or any combination of anticoagulation medication (OR 13.0, 95% CI 1.13 to 150, p=0.032) were significantly associated with bleeding events, while ASA (OR 5.41, 95% CI 0.73 to 40.4, p=0.067) and prophylactic heparin were not (OR 4.68, 95% CI 0.488 to 44.9, p=0.096).

CONCLUSIONS

Current antithrombotic strategies appear effective at attenuating thrombotic risk in pregnant women with a Fontan. However, this comes with high (>30%) bleeding risk, of which 13% are life threatening. Achieving haemostatic balance is challenging in pregnant women with a Fontan, necessitating individualised risk-adjusted counselling and therapeutic approaches that are monitored during the course of pregnancy.

Abdominal Imaging of Children and Young Adults With Fontan Circulation: Pathophysiology and Surveillance

OBJECTIVE. The Fontan procedure has significantly improved the survival in children with a functional single ventricle, but it is associated with chronically elevated systemic venous pressure that leads to multisystemic complications. Imaging plays an important role in assessing these complications and guiding management. The pathophysiology, imaging modalities, and current surveillance recommendations are discussed and illustrated. CONCLUSION. Significant improvement in survival of patients with Fontan circulation is associated with ongoing cardiac and extracardiac comorbidities and multisystemic complications. The liver and intestines are particularly vulnerable to damage. In addition, this patient population has been shown to be at increased risk of certain malignancies such as hepatocellular carcinoma and neuroendocrine tumors. Familiarity with imaging findings of Fontan-associated liver disease and other abdominal complications of the Fontan circulation is essential for radiologists because we are likely to encounter these patients in our general practice.

Direct oral anticoagulant use and outcomes in adult patients with Fontan circulation: A multicenter retrospective cohort study

BACKGROUND

Many adult patients with Fontan circulation are treated with antithrombotic agents, including direct oral anticoagulants (DOACs). However, few studies have investigated the efficacy, feasibility, and safety of DOACs in adult patients with Fontan circulation.

METHODS AND RESULTS

In this retrospective cohort study, clinical records of 139 adult patients with Fontan circulation (70 females, 50.4%) from April 2015 to March 2018 were reviewed and classified into five groups according to the therapeutic agents used: DOAC (n = 36), vitamin K antagonist (VKA; n = 41), antiplatelet drug (n = 43), combination of an antiplatelet and anticoagulant (n = 14), and no-antithrombotic prophylaxis (n = 5). In a 1114-patient-year follow-up, 28 major events occurred, including 10 thrombotic and 18 bleeding events; 11 of 18 (61%) female patients had severe menorrhagia. The incidence (% patient-years) of major events was 0.6, 1.42, 3.74, and 5.13 in the DOAC, antiplatelet, VKA, combination, and no-antithrombotic groups, respectively. The Cox proportional hazards analysis revealed that the DOAC group had a lower rate of primary endpoints than the VKA group in males.

CONCLUSIONS

DOAC may be a safe antithrombotic agent for use in adult patients with Fontan circulation, particularly in males. However, these findings should be confirmed in multi-institutional prospective studies.

Assessment of Late Thromboembolic Complications Post-Fontan Procedure in Relation to Different Antithrombotic Regimens: 30-Years' Follow-up Experience

Background: The current CHEST guidelines recommend the use of antithrombotic therapy, either aspirin or warfarin, as a primary thromboembolic complications (TECs) prophylaxis in patients who undergo Fontan procedure, without specification on drug selection or duration of therapy. Objective: To investigate the incidence rate of late TECs, occurring after 1-year post-Fontan procedure and to assess the difference in rate of late TECs between warfarin and aspirin. Methods: A retrospective cohort study included patients who had Fontan procedures between 1985-2010 at our institution. Patients were stratified according to the antithrombotic regimen-warfarin, aspirin, or no therapy-at the time of TECs. Results: We screened 499 patients who underwent Fontan procedures; 431 procedures met the inclusion criteria. Over a median follow-up of 13.6 years (IQR= 8.7), freedom from late TECs at 5, 10, 15, and 20 years was 97.54%, 96.90%, 90.78%, and 88.07%, respectively. There was no difference in late TEC incidence rates per 1000 patient-years between warfarin and aspirin: 7.82 and 5.83 events, respectively; rate ratio= 1.34 (95% CI= 0.68-2.60). Warfarin was associated with a higher major bleeding incidence rate per 1000 patient-years: 3.70 versus 2.91 events with aspirin; rate ratio= 1.27 (95% CI= 0.49 to 3.29). Conclusion and Relevance: The incidence rate of late clinical TECs post-Fontan procedure in our population is low. Warfarin was not superior to aspirin for prevention of late TECs. Yet warfarin was associated with a higher rate of bleeding. This finding suggests a simpler antithrombotic regimen for prevention of TEC after 1-year post-Fontan procedure.

Establishment of prophylactic enoxaparin dosing recommendations to achieve targeted anti-factor Xa concentrations in children with CHD

BACKGROUND

Enoxaparin may be used to prevent central venous catheter-related thrombosis in patients with CHD. We aimed to determine whether current enoxaparin dosing regimens effectively achieve anti-factor Xa concentrations within prophylactic goal ranges in this patient population.

METHODS

We implemented a formal protocol aimed at reducing central venous catheter-related thrombosis in children with CHD in January, 2016. Standard empiric prophylactic enoxaparin dosing regimens were used - for example, 0.75 mg/kg/dose every 12 hours for patients <2 months of age and 0.5 mg/kg/dose every 12 hours for patients ⩾2 months of age - with anti-factor Xa goal range of 0.25-0.49 IU/ml. Patients <2 years of age who received enoxaparin and had at least one valid steady-state anti-factor Xa measurement between 25 January, 2016 and 31 August, 2016 were retrospectively reviewed.

RESULTS

During the study period, 47 patients had 186 anti-factor Xa concentrations measured, of which 20 (11%) were above and 112 (60%) were below the prophylactic goal range. Anti-factor Xa concentrations within the goal range were ultimately achieved in 31 patients. Median dose required to achieve anti-factor Xa concentrations within the prophylactic range was 0.89 mg/kg/dose (25, 75%: 0.75, 1.11) for patients <2 months (n=23 patients) and 0.79 mg/kg/dose (25, 75%: 0.62, 1.11) for patients ⩾2 months (n=8 patients).

CONCLUSIONS

Enoxaparin doses required to achieve prophylactic anti-factor Xa concentrations in young children with CHD were consistently higher than the currently recommended prophylactic dosing regimens. Further study is needed to determine whether dose titration to achieve prophylactic anti-factor Xa concentrations is effective in preventing central venous catheter-related thrombosis.

Total Cavopulmonary Connection is Superior to Atriopulmonary Connection Fontan in Preventing Thrombus Formation: Computer Simulation of Flow-Related Blood Coagulation

The classical Fontan route, namely the atriopulmonary connection (APC), continues to be associated with a risk of thrombus formation in the atrium. A conversion to a total cavopulmonary connection (TCPC) from the APC can ameliorate hemodynamics for the failed Fontan; however, the impact of these surgical operations on thrombus formation remains elusive. This study elucidates the underlying mechanism of thrombus formation in the Fontan route by using a two-dimensional computer hemodynamic simulation based on a simple blood coagulation rule. Hemodynamics in the Fontan route was simulated with Navier-Stokes equations. The blood coagulation and the hemodynamics were combined using a particle method. Three models were created: APC with a square atrium, APC with a round atrium, and TCPC. To examine the effects of the venous blood flow velocity, the velocity at rest and during exercise (0.5 and 1.0 W/kg) was measured. The total area of the thrombi increased over time. The APC square model showed the highest incidence for thrombus formation, followed by the APC round, whereas no thrombus was formed in the TCPC model. Slower blood flow at rest was associated with a higher incidence of thrombus formation. The TCPC was superior to the classical APC in terms of preventing thrombus formation, due to significant blood flow stagnation in the atrium of the APC. Thus, local hemodynamic behavior associated with the complex channel geometry plays a major role in thrombus formation in the Fontan route.

Transcatheter pulmonary embolectomy after fontan

Pulmonary embolism (PE) is a significant cause of morbidity and mortality among hospitalized patients, and thrombolytics are the mainstay of treatment. However, for patients who fail or have contraindications to thrombolytic therapy, catheter-based therapies, such as the AngioVac aspiration system, have emerged as an alternative to surgical embolectomy. Here, we present the novel case of a 22 year-old woman with Fontan circulation who developed severe postpartum cardiomyopathy and a saddle PE. She failed thrombolytic therapy but underwent successful pulmonary embolectomy by AngioVac aspiration. Patients with Fontan circulation have an increased incidence of thromboembolic events, and AngioVac thrombectomy is a valuable treatment option in these complex patients.

Bone density in children with single ventricle physiology

Children with chronic diseases are at risk for low bone mineral density (BMD). There are no studies of BMD in children with congenital heart disease and particularly single ventricle (SV). Children with this defect are often treated with warfarin, suspected to negatively impact BMD in adults. We assessed BMD in patients with SV physiology and compared the BMD of subjects taking warfarin to those who were not. Subjects 5-12 years with SV were included. BMD z scores by dual-energy X-ray absorptiometry of the spine and total body less head (TBLH) were obtained. Calcium intake, activity level, height, and Tanner stage were assessed. Linear regression models and t tests were used to investigate differences between participants and normative data as well as between subjects' subgroups. Twenty-six subjects were included and 16 took warfarin. Mean BMD z score at the spine was significantly lower than expected at -1.0 ± 0.2 (p < 0.0001), as was the BMD z score for TBLH at -0.8 ± 0.2 (p < 0.0001). Those results remained significant after adjusting for height. Subjects who were on warfarin tended to have lower BMD at both the spine and TBLH than those who were not, with a z score difference of 0.6 ± 0.46 at the spine (p = 0.106) and a difference of 0.4 ± 0.34 at TBLH (p = 0.132). BMD is significantly reduced in children with SV. Warfarin appears to lower BMD but the effect is less conclusive. Continued evaluation is recommended for these patients at risk for reduced bone density. Evaluation of other cardiac patients on warfarin therapy should also be considered.

Results of extracardiac conduit total cavopulmonary connection in 500 patients

OBJECTIVES

This single-institution study aimed to evaluate the early to mid-term outcomes of extracardiac conduit total cavopulmonary connection (EC-TCPC).

METHODS

Between March 1994 and March 2014, 500 patients (median age, 3.4 years) underwent EC-TCPC at our hospital. One hundred and twenty-three patients (24.6%) showed heterotaxy, and fenestration was created in 6 patients (1.2%). The standard institutional treatment policy included postoperative anticoagulation and individualized cardiovascular medication. The mortality and morbidity rates, haemodynamic status, cardiopulmonary exercise capacity and liver examination results during the follow-up period (median, 6.7 years) were retrospectively reviewed.

RESULTS

There were 2 early and 17 late deaths. The Kaplan-Meier estimated survival rate was 96.2% at 10 years and 92.8% at 15 years. Bradyarrhythmia and tachyarrhythmia occurred in 19 and 13 patients, respectively. Other late-occurring morbidities included protein-losing enteropathy in 8, thromboembolism in 5, bleeding complications in 6 and liver cirrhosis in 1 patient. The rate of freedom from late-occurring morbidities was 82.1% at 15 years. In the multivariate analysis, heterotaxy was found to be a predictor for mortality (P = 0.02), whereas age at operation was a predictor for new-onset arrhythmias (P = 0.048). In the cardiopulmonary exercise test (n = 312), the peak VO2 was 84.9 ± 17.3% of the predicted value, which tended to decrease with age (R(2) = 0.32) and elapsed time since operation (R(2) = 0.21). Postoperative cardiac catheterization (n = 468; time from surgery, 3.6 ± 4.3 years) showed central venous pressure of 9.9 ± 2.4 mmHg, ventricular end-diastolic pressure of 5.2 ± 3.3 mmHg, cardiac index of 3.4 ± 0.8 l/min/m(2) and arterial oxygen saturation of 94.2 ± 4.8%. In 101 patients who were followed up for ≥10 years, amino-terminal type III procollagen peptide and collagen type IV levels exceeded the normal ranges in 52.9 and 75.2% of patients, respectively, and liver ultrasonography revealed hyper-echoic spots in 43.3% of patients.

CONCLUSIONS

The early to mid-term outcomes of post-EC-TCPC patients managed with individualized pharmacotherapy were excellent, with low mortality and morbidity rates; however, development of late-occurring morbidities specific to Fontan physiology, including exercise intolerance and liver disease, must be carefully monitored during the long-term follow-up.

Thrombosis and Thromboembolic Complications in Fontan Patients

Hemodynamic fluctuations and thromboembolic complications are significant areas of concern during the postoperative management of patients with univentricular hearts. The objective of this study is to review the incidence and risk factors associated with thrombosis and thromboembolic complications following total cavopulmonary anastomosis, the third stage of the palliative surgical procedure. A literature search of published evidence was conducted on OvidSP MEDLINE(R) and Embase followed by paired title, abstract, and full-text screening based on specific inclusion criteria. High risks of thromboembolic outcomes were identified across studies, with variable incidences between 3% and 20%, high mortality rates up to 38%, and an inverse relationship with prophylaxis treatment administration. Several risk factors for thrombotic complications, including chronic systemic venous hypertension, protein-losing enteropathy, passive blood flow, atrial arrhythmias, conduit stenosis, prosthetic material use, coagulation factor abnormalities, and several patient characteristics were identified. Based on these findings, a prophylactic anticoagulation algorithm has been proposed.

The adult with a fontan: a panacea without a cure? Review of long-term complications

The univentricular heart includes a spectrum of complex cardiac defects that are managed by staged palliative surgical procedures, ultimately resulting in a Fontan procedure. Since 1971, when it was first developed, the procedure has undergone several variations. These patients require lifelong management, including a thorough knowledge of their anatomic substrate, hemodynamic status, management of rhythm and ventricular function, together with multi-organ evaluation. As these patients enter middle age, there is increasing awareness of long-term complications and mortality. This review highlights the concept behind the staged surgical palliations, the unique single ventricle physiology and the long-term complications in this complex cohort of patients.

Thromboembolic complications in Fontan patients: population-based prevalence and exploration of the etiology

After the Fontan procedure, patients face an increased risk for thromboembolic events (TE). The etiology for this increased thrombogenecity is incompletely understood. This study aimed to determine the prevalence of TE in Danish Fontan patients and to bring new insights into the etiology of TE. Using a population-based design, we retrospectively identified all TEs in 210 Fontan patients. Whole blood assays (thromboelastography, thromboelastography functional fibrinogen and Multiplate) reflecting global hemostasis, clot strength and platelet aggregation were analyzed prospectively in 112 patients and plasma was analyzed in 76 patients for biomarkers reflecting endothelial-, glycocalyx-, platelet-, and fibrinolysis function (histone-complexed DNA fragments, Protein C, soluble CD40 ligand, soluble thrombomodulin, syndecan-1, tissue-type plasminogen activator). The results were compared in groups stratified according to age, antithrombotic therapy, TE, and glycocalyx degradation (syndecan-1 < or ≥ median). Correlation between biomarkers and demographic-, anatomical-, clinical- and biochemical parameters was investigated. The prevalence of TE was 8.1 % after a mean follow-up of 8.4 years. None of the stratified groups demonstrated evidence of hypercoagulability in the whole blood assays and no unexpected significant differences were found between the groups. All biomarkers, except protein C, correlated with one another and after stratification of glycocalyx degradation only syndecan-1 levels ≥ median correlated with other biomarkers. The prevalence of TEs was 8.1 % after mean follow-up of 8.4 years. Overall, the hemostatic profile appeared normal, however, in a subset of patients, evidence of some endothelial activation/damage including glycocalyx degradation and fibrinolysis was found, identifying a potentially more thrombogenic group.

Extracardiac complications of the Fontan circuit

The Fontan operation is the primary surgical procedure used in the palliation of patients with univentricular cardiac physiology. With improved survival of children with congenital heart disease, long-term complications of the Fontan circuit are being encountered more frequently. Radiologists are more likely to see both the cardiac and extracardiac complications of the Fontan circuit. Awareness of the common extracardiac complications in children with failing Fontan circuits will aid the radiologist in making the appropriate diagnosis and guide the cardiologist caring for these patients.

Hypoplastic left heart syndrome: current considerations and expectations

In the recent era, no congenital heart defect has undergone a more dramatic change in diagnostic approach, management, and outcomes than hypoplastic left heart syndrome (HLHS). During this time, survival to the age of 5 years (including Fontan) has ranged from 50% to 69%, but current expectations are that 70% of newborns born today with HLHS may reach adulthood. Although the 3-stage treatment approach to HLHS is now well founded, there is significant variation among centers. In this white paper, we present the current state of the art in our understanding and treatment of HLHS during the stages of care: 1) pre-Stage I: fetal and neonatal assessment and management; 2) Stage I: perioperative care, interstage monitoring, and management strategies; 3) Stage II: surgeries; 4) Stage III: Fontan surgery; and 5) long-term follow-up. Issues surrounding the genetics of HLHS, developmental outcomes, and quality of life are addressed in addition to the many other considerations for caring for this group of complex patients.

Supravalvular thrombus after pulmonary artery banding and fontan procedure evaluated by multidetector-row computed tomography

The mechanisms responsible for thromboembolic events in children with congenital heart disease have not yet been fully elucidated. Furthermore, establishment of long-term anticoagulation therapy in Fontan patients remains controversial. Here, we report the case of a 9-year-old boy who presented with hemiparesis due to a thromboembolic stroke; the boy had previously undergone staged pulmonary artery banding and Fontan procedure. Cardiac multidetector-row computed tomography (MDCT) clearly showed the supravalvular thrombus at the roofed (blind) pulmonary valve and circulatory stasis, which could be considered a possible source of the thrombus. Follow-up CT examination showed that the thrombus disappeared, but the circulatory stasis remained. Therefore, because the risk of thrombus formation was not eliminated, anticoagulation therapy was continued for the patient. Our case indicates the possible application of cardiac MDCT for providing insight into the hemodynamic mechanisms responsible for the thromboembolic events in children with congenital heart disease.

Fontan "Ten Commandments" revisited and revised

Choussat's "Ten Commandments," which describes the components of an ideal Fontan candidate, was first published in 1977. Despite the wisdom in these commandments, it is clear from a historic perspective that total compliance with all criteria does not necessarily portend excellent long-term survival. I believe the end point of the original commandments should be modified to include improvement in long-term survival. I suggest the following single commandment: "Thou Shalt Be Perfect."

The Fontan patient: inconsistencies in medication therapy across seven pediatric heart network centers

Patients who have undergone the Fontan procedure are at risk for thrombosis, ventricular dysfunction, and valve regurgitation, but data to guide the medical treatment and prevention of these adverse outcomes in this population are lacking. This analysis examined medication usage among Fontan patients by putative indication and by study center. The medical history and current medications of 546 Fontan subjects, ages 6-18 years, were assessed in a Pediatric Heart Network multicenter cross-sectional study. Cardiac imaging was performed within 3 months of enrollment. The majority of the subjects (64%) were taking two or more medications. Antithrombotics were taken by 86% of those with a history of stroke, thrombosis, or both and 67% of those without such a history (P = 0.01). Conversely, 14% of those with a history of stroke, thrombosis, or both were taking no antithrombotic. Angiotensin-converting enzyme inhibitor (ACEi) therapy was independently associated with moderate or severe atrioventricular valve regurgitation (P = 0.004), right ventricular morphology (P < 0.001), and shorter time since Fontan (P = 0.004) but not with ventricular systolic dysfunction. Glycoside therapy and diuretic therapy each was associated with older age at Fontan (P = 0.001 and P = 0.023, respectively) and a history of post-Fontan arrhythmia (P < 0.001 and P = 0.003, respectively) but not with ventricular systolic dysfunction. Medication use rates varied widely among the centers, even with controls for center differences in patient characteristics. Prospective therapeutic trials are needed to guide the medical treatment of Fontan patients.

Laboratory and clinical predictors of thrombosis and hemorrhage in 29 pediatric extracorporeal membrane oxygenation nonsurvivors

Extracorporeal membrane oxygenation (ECMO) is a life-saving therapy for infants and children with cardiac and respiratory failure. However, thrombosis and hemorrhage are common complications. To determine clinical and laboratory predictors of thrombosis and hemorrhage resulting from ECMO, records and slides were reviewed from 29 consecutive autopsies from 2004 through 2008 of pediatric patients who received ECMO at our institution. Laboratory results, including prothrombin time, activated partial thromboplastin time, platelet count, fibrinogen level, and activated clotting time, were analyzed, as was heparin dosing. Thrombosis and hemorrhage were very common, with 1 or both seen in 86% of patients. Sixty-nine percent had thrombosis, and 52% had hemorrhage after ECMO initiation, including intracranial hemorrhage in 33% of the patients in whom brain examination was permitted. Hemorrhage and thrombosis coexisted in 31% of patients. Thrombosis was significantly more common in patients with congenital cardiac disease. Duration of ECMO therapy, being on ECMO at death, sepsis, and patient age and sex did not predict hemorrhage or thrombosis at autopsy. Laboratory tests were poor predictors of thrombosis and hemorrhage, with no correlation between these complications and prothrombin time, partial thromboplastin time, platelet count, fibrinogen level, activated clotting time, or heparin dose. In conclusion, thrombosis and hemorrhage continue to be frequent complications among patients who die during or after ECMO therapy. Patients with congenital cardiac disease appear especially susceptible to thrombosis on ECMO. Prothrombin time, partial thromboplastin time, platelet count, fibrinogen level, activated clotting time, and heparin dose are poor predictors of thrombosis or hemorrhage for pediatric patients who die after ECMO.

Liver disease after the Fontan procedure: what the hepatologist needs to know

Fifty years ago, only a quarter of infants born with congenital heart disease (CHD) survived beyond the first year of life. It has been estimated that 80% to 85% of patients can expect to reach adulthood. Today, there are close to 1 million adults living with CHD in the United States alone. Since its introduction, the Fontan operation has become established as the dominant surgical repair in patients with univentricular heart physiology. Long-term morbidity associated with this procedure is being more commonly appreciated and liver complications have become more frequently apparent. Hepatologist awareness and familiarity in managing this population alongside the CHD specialist is important for the care of these patients. This dual perspective can provide comprehensive integrated care.

Extracardiac Fontan Operation after Late Bidirectional Glenn Shunt

The outcomes of 33 consecutive extracardiac Fontan operations performed between 1999 and 2008 in patients who mostly had initial Glenn shunts beyond infancy were reviewed. Preoperatively, the median oxygen saturation was 76.2% and mean pulmonary artery pressure was 10.5 mm Hg. The median age was 4.1 years at Glenn shunt procedure and 10 years at Fontan operation. The duration of chest tube drainage was longer in these patients than in series where Glenn shunts were created at a younger age. All patients received warfarin for 1 year, then warfarin and/or aspirin. At follow-up (median, 14 months), there was no significant ventricular dysfunction. Median oxygen saturation at the last follow-up was 92%. All patients in sinus rhythm preoperatively continued in this status. There was no Fontan failure or mortality. All patients were in New York Heart Association class I or II, although objective cardiopulmonary exercise evaluation in 8 patients showed impaired exercise tolerance. Despite a trend towards prolonged pleural effusion, there was no adverse outcome in the short or intermediate term. Long-term follow-up is required to see whether delayed creation of a Glenn shunt is associated with late disadvantages.

Single ventricle physiology: surgical options, indications and outcomes

PURPOSE OF REVIEW

Among the most frequently encountered congenital heart malformations are those with so-called single ventricle physiology, in which there is only one ventricle to pump blood to the pulmonary and systemic vascular beds, respectively. Long-term survival is possible, based on the principle of right heart bypass, whereby the ventricle pumps blood only to the systemic circuit, whereas pulmonary blood flow occurs passively. Such a circulatory system is achieved in a series of staged reconstructive operations, each of which was formerly accompanied by very high rates of major morbidity and mortality. Current approaches to single ventricle physiology as well as areas of controversy will be reviewed.

RECENT FINDINGS

The development of a number of inventive operations, combined with a greater understanding of the physiologic requirements for success after single ventricle reconstruction has resulted in dramatic improvements in outcomes. The identification and modification of risk factors as well as the recent development of catheter-based intervention offer the real prospect of significant continued improvement.

SUMMARY

Advances in the care of children with single ventricle hearts have resulted in remarkably improved prognosis, with the expectation of continued improvement in not only survival but also quality of life.