Pathophysiology of thrombosis and anticoagulation post Fontan surgery

Pregnancy in women with a Fontan circulation: Short and long-term outcomes

BACKGROUND

The Fontan circulation procedure is the palliative surgery of choice for patients with single ventricle physiology, many of whom are now reaching childbearing age due to advances in care. Our study examines the impact of pregnancy on women with Fontan circulation, assessing both short and long-term outcomes.

METHODS

We retrospectively analysed pregnancies in women with Fontan circulation at our centre from 2005 to 2023, including a matched non-pregnant, nulliparous cohort for comparison. Pregnancies lost before 18 weeks were analysed separately.

RESULTS

Among 26 pregnancies in 18 women, preterm births were common (73.1%), with 3 fetal losses and no maternal deaths. Neonatal complications included a 50% incidence of babies small for gestational age (SGA). Cardiac events occurred in 19.2% of pregnancies, primarily supraventricular arrhythmias, and 23% experienced postpartum haemorrhage. Over a median 6.1 [5.2-10.6]-year follow-up, no deaths, heart failure (HF), or Fontan-associated liver disease (FALD) developed, and functional status remained stable.

CONCLUSIONS

Women with a Fontan-type circulation undergoing pregnancy had a few serious maternal cardiac events, though there was a high rate of post-partum haemorrhage. The rates of neonatal complications, particularly related to restricted growth and pre-term birth, were also high. Our findings indicate a generally positive medium-term outlook for these patients, though the impact of pregnancy on long-term survival remains unclear. Careful selection of patients with Fontan circulation during pre-pregnancy counselling may help to reduce complications during and after pregnancy.

The Fontan Circulation in Pregnancy: Hemodynamic Challenges and Anesthetic Considerations

Pregnancy in patients with Fontan physiology presents unique challenges due to altered cardiovascular dynamics inherent to both conditions. The Fontan procedure reroutes venous blood directly to the pulmonary arteries, bypassing the heart, and necessitating precise regulation of pulmonary venous resistance and systemic venous pressure to maintain effective cardiac output. The significant cardiovascular adaptations required during pregnancy to meet the metabolic demands of the mother and fetus can overburden the limited preload capacity and venous compliance in Fontan patients, predisposing them to a spectrum of potential complications, including arrhythmias, heart failure, thromboembolism, and obstetric and fetal risks. This review delineates the essential physiological adaptations during pregnancy and the challenges faced by Fontan patients, advocating for a comprehensive care approach involving multidisciplinary collaboration, vigilant monitoring, tailored anesthetic management, and postpartum care. Understanding the complex dynamics between Fontan physiology and pregnancy is crucial for anesthesiologists to develop and execute individualized management strategies to minimize risks and optimize outcomes for this high-risk population.

Leadless Pacemaker Implantation in Fontan Patients with Multimodality Imaging: Tips and Tricks

Current leadless pacemaker (LP) systems, which have been developed and used in patients with normal cardiac anatomy, are rare and technically even more challenging to implant in patients with congenital heart diseases, especially with univentricular physiology and Fontan palliation. We report two cases of percutaneous LP implantation in an adult and a child, respectively, highlighting the unconventional approaches, different challenges, and use of multimodality imaging in patients who underwent a Fontan operation.

The Effects of Aspirin dose in Children with Congenital and Acquired Heart Disease. Results from the Paediatric Study of Aspirin Efficacy using Diagnostic and Monitoring Tools (PAED-M)

The optimal dose of aspirin required in children with congenital and acquired heart disease is not known. The primary aim of this prospective observational study was to evaluate the effects of aspirin dose on platelet inhibition. The secondary aim was to determine the prevalence and clinical predictors of aspirin non-responsiveness. Measurements were by Thromboelastography with Platelet Mapping (TEGPM) only in children less than 2 years (y) of age with particular emphasis on the parameter known as maximum amplitude with arachidonic acid (MAAA) and using both TEGPM, and light transmission aggregometry (LTA) in children greater than 2 y. We prospectively studied 101 patients with congenital and acquired cardiac disease who were receiving empirical doses of aspirin for a minimum of 4 weeks but no other antiplatelet agents. Patients were stratified according to dose concentration and age. There was a trend toward lower age in patients with no response or semi-response to aspirin. All patients were considered responsive to aspirin in the higher-dose quartile (Q4) with a median dose of 4.72 (4.18-6.05) mg/kg/day suggesting that patients in this age group may require 5 mg/kg/day as an empirical dose. In children > 2 y, there was no significant difference in inhibition found in patients dosed at higher doses in Q3 versus Q4 suggesting that patients in this cohort are responsive with 3 mg/kg/day dose. The current practices may lead to reduced platelet inhibition in some children due to under-dosing or overdosing in others. In conclusion, younger children require higher doses of aspirin. Laboratory assessment is warranted in this population to mitigate against under and overdosing.

Coagulation Profile in Neonates with Congenital Heart Disease: A Pilot Study

Background and Objectives: congenital heart disease (CHD), cyanotic and, to a lesser degree, acyanotic, often are accompanied by coagulation abnormalities, impacting substantially morbidity and mortality. Until now, no consistent hemostatic patterns have been demonstrated in neonates and children with CHD because they represent a variable and heterogenous population. The aim of the present study is to investigate the hemostatic profile, as well as the role of ADAMTS-13 (a disintegrin and metalloprotease with thrombospondin type-1 motives), the cleaving protein of von Willebrand factor (VWF) in neonates with CHD and compare them to healthy age-matched controls. Materials and Methods: twenty neonates with a mean gestational age of 37.1 ± 2.5 weeks were included in the CHD group, and 18 healthy neonates with a mean gestational age of 38.2 ± 1.5 weeks were in the control group. Results: prothrombin time was significantly prolonged, and accordingly, factor VII (FVII) levels were significantly decreased in the CHD group in comparison to controls. Factor VIII (FVIII), VWF, and ristocetin cofactor activity (Rcof) levels were significantly higher in the study vs. control group. Concentrations of ADAMTS-13 were decreased in the CHD vs. control group, but the difference was not statistically significant. Our results, in combination, indicate a balanced hemostatic mechanism, although with greater variability in neonates with CHD, while developmental aspects of coagulation are evident in the specific patient population. Conclusions: the coagulation profile is moderately impaired early in the course of CHD, though increased thrombogenicity is already present and should not be ignored.

Long-Term Outcomes and Characteristics Associated With Mortality of Adult Patients Post Fontan Surgery: 27-Year Single-Center Experience

Data on the characteristics and long-term outcomes of patients who underwent Fontan surgery and surviving into adulthood are limited. We aimed to describe our center's long-term experience with this unique patient population. Included were adult patients who had undergone Fontan surgery and were followed up at our Adult Congenital Heart Disease clinic between the years 1994 and 2021. We describe cardiac and noncardiac morbidities, medical treatment, laboratory data, echocardiographic characteristics, and all-cause mortality. The primary outcome was a composite of heart failure hospitalizations or death. A total of 107 patients who underwent Fontan surgery were followed up during the study period; 46.7% were male. The mean age at time of Fontan was 7.4 ± 6.2 years and the mean age at the last follow-up or at the time of an outcome event was 35.0 ± 8.0 years (range 21.1 to 62.8). At the last documented follow-up, 74.7% of the cohort were in New York Heart Association functional class I/II. The common morbidities included atrial arrythmias (37%) and stroke (17%). The primary outcome occurred in 17.7%. By the end of the study period, 9.3% of the patients in the cohort died. In a multivariate logistic regression analysis, controlling for gender, age, and Fontan type, worse functional class at the last follow-up (New York Heart Association III/IV vs I/II) was significantly associated with the risk of the primary outcome (odds ratio 34.57, 95% confidence interval 6.728 to 177.623, p <0.001). In conclusion, long-term outcomes of patients surviving into adulthood with a Fontan circulation is encouraging. Most of these patients achieve good functional cardiovascular status, despite the complex anatomy and a substantial burden of co-morbid conditions, specifically, atrial arrythmias and thrombotic events. Functional class was independently associated with heart failure hospitalizations and mortality.

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.

Hemostasis assessment in Fontan patients using the new thrombodynamics test

BACKGROUND

Thromboembolic events are a well-known risk for Fontan patients and often lead to morbidity and mortality in cyanotic patients and patients with a single ventricle. Coagulopathy and thrombophilia, in addition to disturbed Fontan blood flow and endothelial injury, are major contributors to thromboembolic complications. However, there is currently no consensus regarding the optimal medication to prevent or treat these events. Identification of coagulation disorders is therefore crucial for selecting appropriate management strategies and evaluating long-term outcomes in these patients.

CASE PRESENTATION

We present the case of a 35-year-old male who underwent the Fontan procedure with a total cavopulmonary modification during childhood due to tricuspid atresia. He was admitted with complaints of headaches and visual disturbances, but no clear cardiovascular cause was identified. Standard coagulation test parameters were normal, but the thrombodynamics test indicated severe hypercoagulation and spontaneous clot formation. Anticoagulation therapy was initiated, and a subsequent thrombodynamics assay showed normalization of the coagulation parameters. The patient remained asymptomatic during the six-month follow-up period.

CONCLUSIONS

The thrombodynamics test is a valuable tool for the diagnosis of coagulation disorders, as it can assess coagulation parameters and clot growth in vitro. This method can also aid in the optimization of antithrombotic therapy. The presented clinical case highlights the potential use of the thrombodynamics test in Fontan patients to diagnose coagulation disorders and improve long-term outcomes.

Percutaneous rheolytic thrombectomy and cerebral embolic protection in a massive thrombosis of a fenestrated Fontan conduit: a case report

Background

Clinical thromboembolism in Fontan patients is often a catastrophic event resulting in death and adverse long-term outcomes. The treatment of acute thromboembolic complications in these patients is very controversial.

Case summary

We describe the use of rheolytic thrombectomy in a Fontan patient with life-threatening pulmonary embolism, employing a cerebral protection system to reduce the risk of stroke through the fenestration.

Discussion

Rheolytic thrombectomy may be a successful alternative to systemic thrombolytic therapy and open surgical resection for the treatment of acute high-risk pulmonary embolism in the Fontan population. Embolic protection device to capture and remove thrombus/debris may be an innovative tool to reduce the risk of stroke through the fenestration while performing a percutaneous procedure in fenestrated Fontan patient.

Fontan-associated liver disease: Diagnosis, surveillance, and management

The Fontan operation is a lifesaving procedure for patients with functional single-ventricle congenital heart disease, where hypoplastic left heart syndrome is the most frequent anomaly. Hemodynamic changes following Fontan circulation creation are now increasingly recognized to cause multiorgan affection, where the development of a chronic liver disease, Fontan-associated liver disease (FALD), is one of the most important morbidities. Virtually, all patients with a Fontan circulation develop liver congestion, resulting in fibrosis and cirrhosis, and most patients experience childhood onset. FALD is a distinctive type of congestive hepatopathy, and its pathogenesis is thought to be a multifactorial process driven by increased nonpulsatile central venous pressure and decreased cardiac output, both of which are inherent in the Fontan circulation. In the advanced stage of liver injury, complications of portal hypertension often occur, and there is a risk of developing secondary liver cancer, reported at young age. However, FALD develops with few clinical symptoms, a surprisingly variable degree of severity in liver disease, and with little relation to poor cardiac function. The disease mechanisms and modifying factors of its development are still not fully understood. As one of the more important noncardiac complications of the Fontan circulation, FALD needs to be diagnosed in a timely manner with a structured monitoring scheme of disease development, early detection of malignancy, and determination of the optimal time point for transplantation. There is also a clear need for consensus on the best surveillance strategy for FALD. In this regard, imaging plays an important role together with clinical scoring systems, biochemical workups, and histology. Patients operated on with a Fontan circulation are generally followed up in cardiology units. Ultimately, the resulting multiorgan affection requires a multidisciplinary team of healthcare personnel to address the different organ complications. This article discusses the current concepts, diagnosis, and management of FALD, with special emphasis on the role of different imaging techniques in the diagnosis and monitoring of disease progression, as well as current recommendations for liver disease surveillance.

Thromboprophylaxis in Patients With Fontan Circulation

BACKGROUND

The optimal strategy for thromboprophylaxis in patients with a Fontan circulation is unknown.

OBJECTIVES

The aim of this study was to compare the efficacy and safety of aspirin, warfarin, and nonvitamin K oral anticoagulants (NOACs) in a network meta-analysis.

METHODS

Relevant studies published by February 2022 were included. The primary efficacy outcome was thromboembolic events; major bleeding was a secondary safety outcome. Frequentist network meta-analyses were conducted to estimate the incidence rate ratios (IRRs) of both outcomes. Ranking of treatments was performed based on probability (P) score.

RESULTS

A total of 21 studies were included (26,546 patient-years). When compared with no thromboprophylaxis, NOAC (IRR: 0.11; 95% CI: 0.03-0.40), warfarin (IRR: 0.23; 95% CI: 0.14-0.37), and aspirin (IRR: 0.24; 95% CI: 0.15-0.39) were all associated with significantly lower rates of thromboembolic events. However, the network meta-analysis revealed no significant differences in the rates of major bleeding (NOAC: IRR: 1.45 [95% CI: 0.28-7.43]; warfarin: IRR: 1.38 [95% CI: 0.41-4.69]; and aspirin: IRR: 0.72 [95% CI: 0.20-2.58]). Rankings, which simultaneously analyze competing interventions, suggested that NOACs have the highest P score to prevent thromboembolic events (P score 0.921), followed by warfarin (P score 0.582), aspirin (P score 0.498), and no thromboprophylaxis (P score 0.001). Aspirin tended to have the most favorable overall profile.

CONCLUSIONS

Aspirin, warfarin, and NOAC are associated with lower risk of thromboembolic events. Recognizing the limited number of patients and heterogeneity of studies using NOACs, the results support the safety and efficacy of NOACs in patients with a Fontan circulation.

Dissimilarity in coagulation system in adults after Fontan surgery based on thrombin generations

OBJECTIVES

The Fontan procedure is the treatment of choice in congenital cardiac malformations defined as the single ventricle. Fontan patients are at high risk of thromboembolism, but the exact mechanism of this is poorly understood. The aim of this study was to evaluate an involvement of thrombin generations and microparticles (MPs) in prothrombotic state in adults with Fontan circulation.

METHODS

This study included hospitalized patients after Fontan procedure and healthy volunteers. We assessed laboratory tests including thrombin generation by calibrated automated thrombography in three variants [platelet-poor plasma (impact of coagulation factors), platelet-rich plasma (PRP) (influence of platelets) and related with MPs]. The technique allows for a comprehensive evaluation of the coagulation system.

RESULTS

The study groups consisted of 81 adult Fontan patients [41 females (50.6%); median age 22 interquartile range [20-27] years] and 54 control subjects. In patients with Fontan circulation, higher values of endogenous thrombin potential and peak values were observed for both platelet-poor plasma (+17% and +33%) and MPs (+29% and 41%) compared to controls (all P < 0.05). Moreover, in the Fontan group, we found a 64.9% shorter lag time and a 70.4% time to peak for MP variant (both P < 0.001). Contrarily, analysis in the PRP showed 17.1% of reduced endogenous thrombin potential in Fontan. Furthermore, there were no differences in thrombin synthesis in PRP in Fontan patients receiving aspirin or those with thrombocytopaenia (all P > 0.05).

CONCLUSIONS

This study for the first time showed that thrombin generation associated with MPs may be an important contributor to the prothrombotic state in the Fontan population.

Potential of the EVAHEART 2 Double-Cuff Tipless Inflow Cannula for Prevention of Thromboembolic Events

A 32-year-old man, who had developed fulminant myocarditis leading to asystole, underwent implantation of an EVAHEART 2 left ventricular assist system with a double-cuff tipless inflow cannula and a concurrent Fontan operation. Approximately 2 years after the simultaneous EVAHEART 2 implantation and the Fontan operation, the patient underwent heart transplantation. There was no device-related thromboembolism or pump malfunction under adequate antithrombotic management during the postoperative support period. Computed tomography showed no malposition of the inflow cannula irrespective of the left ventricular chamber size. Macroscopically, the left ventricular cavity of the excised heart revealed a smooth inflow ostium with appropriate intimal proliferation and without pannus or wedge thrombus formation. These findings suggest the utility of the double-cuff tipless inflow cannula for long-term clinical applications, which may lead to favorable outcomes during long-term patient management. The double-cuff tipless inflow cannula, which does not protrude into the left ventricular cavity, potentially contributes to the prevention of suction events and the collision of the inflow cannula with the interventricular septum and left ventricular free wall. Further investigation is required to confirm the role of the unique EVAHEART 2 inflow cannula in reducing thromboembolic events.

Does COVID-19 pose a threat for patients after univentricular palliation? Thrombosis of the Fontan tunnel

A 6-year-old boy, born with hypoplastic left heart syndrome, underwent total cavopulmonary connection and later presented in a significantly deteriorated condition. A CT scan revealed multiple thrombi in the extracardiac conduit, although the patient was maintained on an effective anticoagulant therapy. Further examination revealed anamnestic antibodies suggesting that the patient had gone through a clinically inapparent COVID-19 infection, which we conclude most likely contributed to his hypercoagulable state and led to the formation of significant thrombi impairing the patient's haemodynamics. The patient underwent a surgical thrombectomy; there were no post-operative thrombotic complications.

Reproductive Issues in Patients With the Fontan Operation

Patients with the Fontan operation have a unique circulation, with a limited ability to increase cardiac output, and high central venous pressure. They may have diastolic and/or systolic ventricular dysfunction, arrhythmias, thromboembolic complications, or multiorgan dysfunction. All of these factors contribute to reproductive issues, including menstrual irregularities, infertility, recurrent miscarriage, and complications during pregnancy. Although atrial arrhythmias are the most common cardiac complications during pregnancy, patients can develop heart failure and thromboembolic events. Obstetric bleeding, including postpartum hemorrhage, is common. In addition to maternal complications, adverse fetal and neonatal events, such as prematurity and low birthweight, are very common. Counselling about these reproductive issues should begin early. For those who become pregnant, care should be provided by a multidisciplinary cardio-obstetric team familiar with the specific issues and needs of the Fontan population. In this review, we discuss infertility, contraception, and pregnancy in patients with the Fontan operation.

Modified AngioVac System use With Extracorporeal Membrane Oxygenation in a Child With Fontan Thrombosis

The AngioVac System (AVS) extracts venous and pulmonary artery (PA) thrombi. We report modified use of the second-generation AVS with concurrent venoarterial extracorporeal membrane oxygenation (VA-ECMO) in a 10-year-old, 23 kg patient with failing Fontan circulation due to acute-on-chronic Fontan and PA thrombosis. Emergent femoral VA-ECMO was initiated for profound hypoxemia during cardiac catheterization. Fluoroscopy-guided thrombo-embolectomy was performed with AVS components. A two-venous limb inflow cannulation strategy was used; the AngioVac cannula (AVC) was positioned in the central PA and joined to the existing ECMO venous-limb. Thrombus extraction proceeded by clamping the ECMO venous-limb with the existing VA-ECMO centrifugal pump generating negative pressure to the AVC. Extracorporeal membrane oxygenation arterial-limb access was used for blood return. Settings to avoid cavitation were a maximal negative pressure of 100 mmHg using <3500 RPMs. To access the branch PAs, the AVC was replaced by a custom-modified 17 Fr arterial ECMO cannula. Clot retrieval was sufficient for improved clinical status enabling ECMO discontinuation within 24-hours, and discharge home 26-days later. This is the first description of successful subtotal thrombo-embolectomy with AVS components in a child with Fontan physiology concurrently supported on VA-ECMO, using one centrifugal pump. Although feasible, circuit modifications and close monitoring are required to avoid complications.

The absence of warfarin treatment and situs inversus are associated with the occurrence of hepatocellular carcinoma after Fontan surgery

BACKGROUND

Hepatocellular carcinoma (HCC) is a long-term complication of Fontan-associated liver disease (FALD). However, risk factors for HCC in patients with FALD remain unclear. This study aimed to identify factors associated with HCC development post-Fontan procedure.

METHODS

We retrospectively examined 103 post-Fontan patients who underwent hepatic imaging at our institution. HCC incidence and patient characteristics were analyzed. A Cox proportional hazards model was used to identify risk factors for HCC.

RESULTS

The median interval between Fontan surgery and final hepatic imaging was 19.6 (1.0-37.7) years. Among 103 patients, nine developed HCC. The cumulative incidence rates of HCC at 10, 20, and 30 years postoperatively were 0%, 7%, and 13%, respectively. In the univariate analysis, age at Fontan surgery, situs inversus, and warfarin absence were associated with HCC occurrence. The multivariate analysis identified the warfarin absence (adjusted hazard ratio [aHR], 22.71; 95% confidence interval: 3.29-507.1; p = 0.0005) and situs inversus (aHR, 14.36; 95% confidence interval: 2.75-105.5; p = 0.002) as risk factors. The prevalence of situs inversus and the warfarin absence was 12% and 50%, respectively. The 20- and 30-year incidence rates of HCC among patients who received warfarin were 0% and 7%, respectively, while those among patients who did not receive warfarin were 14% and 21%, respectively. HCC incidence was significantly higher in the non-warfarin group than in the warfarin group (p = 0.006) and among patients with situs inversus than among those with situs solitus (p = 0.004).

CONCLUSIONS

Warfarin absence and situs inversus were associated with HCC development post-Fontan procedure.

Adverse Events of DOACs in Children

Venous thromboembolism (VTE) has an increasing rate of significance in pediatric patients. The currently standardized anticoagulants (unfractionated heparin, low molecular weight heparin and vitamin K antagonists) and their dose regimens were not comprehensively trialed in pediatric patients. Recently, several direct oral anticoagulants (DOACs) have been studied in clinical trials in the pediatric population and further trials are ongoing. Dabigatran etexilate and rivaroxaban results show that these DOACs are safe and efficient in the treatment and secondary prevention of pediatric VTE. This review will focus on adverse events (AEs) between specific DOACs reported in the clinical trials in children and compare them to standard of care. This will assist clinicians in decision making of selecting the right anticoagulation for their pediatric patients.

Fontan circulation has improved life expectancy for infants born with complex heart disease over the last 50 years but has also resulted in significant morbidity

The prognosis for infants born with complex heart disease improved dramatically with the introduction of the Fontan circulation 50 years ago. With today's carefully designed and staged operations to a Fontan circulation, life expectancy has increased and most children will survive into adult life. The Fontan circulation entails an unphysiological circulation with high risk for multiple organ system dysfunction. Neurodevelopmental disabilities with adverse psychosocial effects are prevalent. The Fontan circulation may eventually fail and necessitate heart transplantation. CONCLUSION: Fifty years development of the Fontan circulation to today's staged surgical procedures has improved survival but also revealed the burden of a high morbidity for a growing number of patients.

Increased Risk for Thromboembolism After Fontan Surgery: Considerations for Thromboprophylaxis

The Fontan circulation introduces an increased risk of thromboembolism which is associated with substantial mortality and morbidity. Adverse outcomes of thromboembolic complications post-Fontan surgery vary in both nature and severity, ranging from local tissue infarction and pulmonary embolism to Fontan failure and ischemic stroke. Furthermore, recent studies have identified that subclinical stroke is common yet underdiagnosed in Fontan patients. Fontan patients are commonly treated with antiplatelet agents and/or anticoagulants as primary thromboprophylaxis. Optimal thromboprophylaxis management in the Fontan population is still unclear, and clinical consensus remains elusive despite the growing literature on the subject. This perspective will describe the nature of thromboembolism post-Fontan surgery and provide evidence for the use of both current and emerging thromboprophylaxis options for children and adults living with Fontan circulation.

Thromboprophylaxis for Children Post-Fontan Procedure: Insights From the UNIVERSE Study

Background Patients with single-ventricle physiology who undergo the Fontan procedure are at risk for thrombotic events associated with significant morbidity and mortality. The UNIVERSE Study evaluated the efficacy and safety of a novel liquid rivaroxaban formulation, using a body weight-adjusted dosing regimen, versus acetylsalicylic acid (ASA) in children post-Fontan. Methods and Results The UNIVERSE Study was a randomized, multicenter, 2-part, open-label study of rivaroxaban, in children who had undergone a Fontan procedure, to evaluate its dosing regimen, safety, and efficacy. Part A was the single-arm part of the study that determined the pharmacokinetics/pharmacodynamics and safety of rivaroxaban in 12 participants before proceeding to part B, whereby 100 participants were randomized 2:1 to open-label rivaroxaban versus ASA. The study period was 12 months. A total of 112 participants were enrolled across 35 sites in 10 countries. In part B, for safety outcomes, major bleeding occurred in one participant on rivaroxaban (epistaxis that required transfusion). Clinically relevant nonmajor bleeding occurred in 6% of participants on rivaroxaban versus 9% on ASA. Trivial bleeding occurred in 33% of participants on rivaroxaban versus 35% on ASA. For efficacy outcomes, 1 participant on rivaroxaban in part B had a pulmonary embolism (2% overall event rate); and for ASA, 1 participant had ischemic stroke and 2 had venous thrombosis (9% overall event rate). Conclusions In this study, participants who received rivaroxaban for thromboprophylaxis had a similar safety profile and fewer thrombotic events, albeit not statistically significant, compared with those in the ASA group. Registration URL: https://www.clinicaltrials.gov. Identifier: NCT02846532.

Risk Factors of Thrombotic Complications and Antithrombotic Therapy in Paediatric Cardiosurgical Patients

The development of cardiosurgical care for paediatric and neonatal patients is undergoing the rapid growth. Complex, multi-stage reconstructive operations and the use of invasive monitoring are associated with high risk of venous and arterial thrombosis.

The cardiac surgery patient is inherently unique, since it requires controlled anticoagulation during cardiopulmonary bypass. Moreover, the most cardiovascular pediatric patients require antithrombotic measures over the perioperative period. In addition to medication support with the use of various groups of antithrombotic agents, vascular access management is justified in order to minimize the risk of thromboembolic complications, which can affect both the functional status, and common and inter-stage mortality.

The purpose of this review was to systematize the available data on risk factors contributing to the development of thrombotic complications in patients with congenital heart disease.

An information search was carried out using Internet resources (PubMed, Web of Science, eLibrary.ru); literature sources for period 2015–2020 were analysed. As a result of the analysis of the literature data age-dependent features of the haemostatic system, and associated with the defect pathophysiology, and undergone reconstructive interventions were described. The issues of pathophysiology of univentricular heart defects and risk factors associated with thrombosis were also covered.

Moreover, aspects of intraoperative anti-thrombotic support are discussed, as well as measures to prevent thromboembolic complications in this population.

Coordinated actions of haematologists, cardiologists, anaesthesiologists, intensivists, and cardiac surgeons will allow achieving a fine balance between risks of bleeding and thrombosis in the population of paediatric patients undergoing cardiovascular surgery. 

Carotid approach to anterior circulation thromboembolectomy in an adult with failing fontan physiology: a case report

Background

Anesthetic management of an adult with failing Fontan physiology is complicated given inherent anatomical and physiological alterations. Neurosurgical interventions including thromboembolectomy may be particularly challenging given importance of blood pressure control and cerebral perfusion.

Case Presentation

We describe a 29 year old patient born with double outlet right ventricle (DORV) with mitral valve atresia who after multi-staged surgeries earlier in life, presented with failing Fontan physiology. She was admitted to the hospital almost 29 years after her initial surgeries to undergo workup for a dual heart and liver transplant in the context of a failing Fontan with elevated end diastolic pressures, NYHA III heart failure symptoms, and liver cirrhosis from congestive hepatopathy. During the workup in the context of holding anticoagulation for invasive procedures, she developed a middle cerebral artery (MCA) stroke requiring a thromboembolectomy via left carotid artery approach.

Discussion and Conclusions

This case posed many challenges to the anesthesiologist including airway control, hemodynamic and cardiopulmonary monitoring, evaluation of perfusion, vascular access, and management of anticoagulation in an adult patient in heart and liver failure with Fontan physiology undergoing thromboembolectomy for MCA embolic stroke.

Could DOAC Be a Better Choice Than Warfarin in Low Compliance Patients with Fontan Procedure?

Background and Objectives: After the Fontan procedure, thromboembolic events need to be prevented. We present a young patient with a history of Fontan procedure and poor adherence to warfarin who developed systemic thromboembolism. He was changed to maintenance dabigatran, which is one of the available direct oral anticoagulants (DOACs). Case presentation: A 20-year-old man was diagnosed with cerebral infarct, pulmonary thromboembolism (PTE), and renal infarcts. He was prescribed warfarin to prevent thromboembolic events after the Fontan procedure. Based on his poor adherence to warfarin, we decided to change the anticoagulant therapy from warfarin to dabigatran 150 mg bid. One month later, his pulmonary thromboembolism regressed. Conclusion: Our case report showed a young adult with low compliance to warfarin who developed cerebral, pulmonary, and renal thromboembolic events. Thus, in our opinion, the change from warfarin to a DOAC was necessary for further prevention and treatment of PTE. A change from warfarin to a DOAC should be considered in patients with poor compliance who are at high risk of thromboembolic events, for example, after the Fontan procedure.

Cross-sectional assessment of haemostatic profile and hepatic dysfunction in Fontan patients

Background

Fontan-associated liver disease is accompanied by a hypercoagulable state. While hepatic dysfunction in Fontan patients is common, its relationship with haemostatic changes and clinical outcomes in this patient population remains unclear.

Objective

To correlate liver dysfunction and haemostatic profiles with clinical outcomes in the Fontan population.

Patients/methods

Patients were enrolled in a multicentre, cross-sectional study in Australia and New Zealand. Hepatic structure and function were assessed using serum-based calculations (Fibrotest and model for end-stage liver disease excluding international normalised ratio scores). Haemostatic profiles were assessed by Thrombin Generation. Platelet function was assessed via Platelet Factor 4 (PF4) and P-selectin (P-SEL). Clinical outcomes were obtained from the Australian and New Zealand Fontan Registry.

Results

Seventy-three patients participated in the study (mean age 18.9±8.5 years with a mean of 13.5±6.9 years post-Fontan). The Endogenous Thrombin Potential (ETP) for patients who suffered thrombotic events (TE) (1366.4±66.2 nM/min) was higher compared with patients with major bleeding events (1011.1±138.4 nM/min) (p=0.03). Except for a negative correlation between Fibrotest-score and PF4 (p=0.045), PF4 and P-SEL concentrations did not correlate with markers of hepatic dysfunction or structural abnormality.

Conclusions

Increased ETP is associated with TE during clinical follow-up after Fontan. This study reinforces that hepatic dysfunction may contribute to the derangement of coagulation factors, impacting the individual risk of haemostatic complications for the Fontan population.

Early Thromboprophylaxis Initiation is Associated With Reduced Fontan Thromboses in the Early Postoperative Period

Fontan circuit thrombosis is a significant cause of early postoperative morbidity and mortality. Thrombosis incidence and relationship to thromboprophylaxis choice and timing of initiation are not well established. We sought to evaluate the incidence of Fontan circuit thrombosis in the first 30 postoperative days and its relationship to thromboprophylaxis choice and timing. Patients undergoing Fontan surgery, 2006-2016, were reviewed. Fontan circuit thrombosis was defined by sonographic detection of intracardiac or deep venous thrombi. Logistic regression was used to assess relationships between thromboprophylaxis characteristics and thrombosis. One hundred ninety-two patients underwent Fontan. Fontan thrombosis occurred in 19 (10%) patients. 54% were started on aspirin, 27% coumadin, 4% heparin, and 7% none. There was no relationship between thrombosis and baseline anatomy, Fontan type or fenestration. Median time to thromboprophylaxis initiation was 4 days (interquartile range 2-6). Patients not started on thromboprophylaxis had 44.8 times the odds of thrombosis as those on thromboprophylaxis (confidence interval 6.4-311.7, P < 0.01); no children starting thromboprophylaxis before postoperative day 2 developed thromboses. For every day that thromboprophylaxis was delayed, odds of thrombosis increased by 30% (odds ratio 1.3; CI 1.1-1.6, P < 0.01). There was no difference in the odds of thrombosis between children taking aspirin vs other thromboprophylaxis types. Odds of early postoperative Fontan circuit thrombosis are increased in patients in whom thromboprophylaxis is delayed beyond the second postoperative day, with no difference in the odds of thrombosis between patients initiated on aspirin vs other thromboprophylaxis. Early aspirin institution post Fontan is recommended to reduce morbidity. Ultra-mini-Abstract: Odds of early postoperative Fontan circuit thrombosis are increased in patients in whom thromboprophylaxis is delayed beyond the second postoperative day, with no difference in the odds of thrombosis between patients initiated on aspirin vs other thromboprophylaxis. Early aspirin institution post Fontan is recommended to reduce morbidity and resource utilization.

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.