Central venous thrombosis after cardiac operations in children

Incidence and Timing of Thrombosis After the Norwood Procedure in the Single-Ventricle Reconstruction Trial

Background Thrombosis is common in infants undergoing staged surgeries for single-ventricle congenital heart disease. The reported incidence and timing of thrombosis varies widely, making it difficult to understand the burden of thrombosis and develop approaches for prevention. We aimed to determine the timing and cumulative incidence of thrombosis following the stage I Norwood procedure and identify clinical characteristics associated with thrombosis. Methods and Results We analyzed data from the Pediatric Heart Network Single Ventricle Reconstruction trial from 2005 to 2009 and identified infants with first-time thrombotic events. In 549 infants, the cumulative incidence of thrombosis was 21.2% (n=57) from stage I through stage II. Most events occurred during stage I (n=35/57, 65%), with a median time to thrombosis of 15 days. We used a Cox proportional hazards model to estimate the association of clinical variables with thrombosis. After adjusting for baseline variables, boys had a higher hazard of thrombosis (adjusted hazard ratio [HR], 2.69; 95% CI, 1.44-5.05; P=0.002), non-hypoplastic left heart syndrome cardiac anatomy was associated with a higher early hazard of thrombosis (adjusted HR, 3.93; 95% CI, 1.89-8.17; P<0.001), and longer cardiopulmonary bypass time was also associated with thrombosis (per 10-minute increase, adjusted HR, 1.07; 95% CI, 1.01-1.12; P=0.02). Lower oxygen saturation after the Norwood procedure increased the hazard for thrombosis in the unadjusted model (HR, 1.08; 95% CI, 1.02-1.14; P=0.011). Conclusions Thrombosis affects 1 in 5 infants through Stage II discharge, with most events occurring during stage I. Male sex, non-hypoplastic left heart syndrome anatomy, longer cardiopulmonary bypass time, and lower stage I oxygen saturation were associated with thrombosis.

Upper body peripherally inserted central catheter in pediatric single ventricle patients

BACKGROUND

There is risk of stenosis and thrombosis of the superior vena cava after upper extremity central catheter replacement. This complication is more serious among patients with single ventricle physiology, as it might preclude them from undergoing further life-sustaining palliative surgery.

AIM

To describe complications associated with the use of upper extremity percutaneous intravenous central catheters (PICCs) in children with single ventricle physiology.

METHODS

A single institution retrospective review of univentricular patients who underwent superior cavopulmonary anastomoses as their stage 2 palliation procedure from January 2014 until December 2018 and had upper body PICCs placed at any point prior to this procedure. Clinical data including ultrasonography, cardiac catheterization, echocardiogram reports and patient notes were used to determine the presence of thrombus or stenosis of the upper extremity and cervical vessels. Data regarding the presence and duration of upper extremity PICCs and upper extremity central venous catheter (CVC), and use of anticoagulation were recorded.

RESULTS

Seventy-six patients underwent superior cavopulmonary anastomoses, of which 56 (73%) had an upper extremity PICC at some point prior to this procedure. Median duration of PICC usage was 24 d (25%, 75%: 12, 39). Seventeen patients (30%) with PICCs also had internal jugular or subclavian central venous catheters (CVCs) in place at some point prior to their superior cavopulmonary anastomoses, median duration 10 d (25%, 75%: 8, 14). Thrombus was detected in association with 2 of the 56 PICCs (4%) and 3 of the 17 CVCs (18%). All five patients were placed on therapeutic dose of low molecular weight heparin at the time of thrombus detection and subsequent cardiac catheterization demonstrated resolution in three of the five patients. No patients developed clinically significant venous stenosis.

CONCLUSION

Use of upper extremity PICCs in patients with single ventricle physiology prior to super cavopulmonary anastomosis is associated with a low rate of catheter-associated thrombosis.

In silico features of ADAMTS13 contributing to plasmatic ADAMTS13 levels in neonates with congenital heart disease

INTRODUCTION

Risk factors contributing to heightened thrombosis in pediatric congenital heart disease (CHD) patients are not fully understood. Among the neonatal CHD population, those presenting with single ventricular physiology are at the highest risk for perioperative thrombosis. The von Willebrand factor and ADAMTS13 interactions have emerged as causative risk factors for pediatric stroke and could contribute to heightened thrombosis in CHD neonates.

METHODS

This study investigates a cohort of children with single ventricle physiology and undergoing cardiac surgery, during which some patients developed thrombosis. In this cohort, we analyzed the relationship of several molecular features of ADAMTS13 with the plasma and activity levels in patients at risk of thrombosis. Additionally, in light of the natural antithrombotic activity of ADAMTS13, we have sequenced the ADAMTS13 gene for each patient and evaluated the role of genetic variants in determining the plasma ADAMTS13 levels using a series of in silico tools including Hidden Markov Models, EVmutation, and Rosetta.

RESULTS

Lower ADAMTS13 levels were found in patients that developed thrombosis. A novel in silico analysis to assess haplotype effect of co-occurring variants identified alterations in relative surface area and solvation energy as important contributors. Our analysis suggested that beneficial or deleterious effect of a variant can be reasonably predicted by comprehensive analysis of in silico assessment and in vitro and/or in vivo data.

CONCLUSION

Findings from this study add to our understanding the role of genetic features of ADAMTS13 in patients at high risk of thrombosis related to an imbalanced relation between VWF and ADAMTS13.

Epidemiology and outcomes of clinically unsuspected venous thromboembolism in children: A systematic review

BACKGROUND

Clinically unsuspected venous thromboembolic events (uVTE) detected during routine imaging pose a management challenge due to limited knowledge about their clinical significance. Unsuspected VTE are often referred as "asymptomatic," "incidental," or "clinically silent/occult" VTE.

OBJECTIVE

To understand the epidemiology, management, and outcomes of uVTE in children.

METHODS

A systematic review was performed according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. The search criteria included controlled vocabulary and keywords for VTE, incidental findings, and children (ages ≤ 21 years).

RESULTS

Among 10 875 articles, 51 studies (8354 children with 758 uVTE) were selected. The studies were heterogeneous, I2 96%; P < .0001. Unsuspected VTE were diagnosed in two settings: first, asymptomatic VTE (aVTE) diagnosed through surveillance imaging for VTE (46 studies; n = 5894; aVTE: 715, pooled frequency: 19%, 95% confidence interval [CI]: 13%-24%); second, incidental VTE (iVTE) diagnosed during imaging performed for indications without primary suspicion for VTE (6 studies; n = 2460; iVTE: 43). The majority (94%) of aVTE were associated with central venous lines (CVL). Non-CVL settings included post-spinal surgery, post-splenectomy, trauma, nephrotic syndrome, and newborns. In general, aVTE were reported to have a benign clinical course, were mostly transient, and resolved without intervention and with few immediate or long-term functional complications. Incidental VTE were primarily detected in children with cancer and ranged from tumor-associated thrombi to pulmonary embolism (PE) with insufficient evidence to draw meaningful conclusions about their management.

CONCLUSION

Clinically uVTE were predominantly diagnosed with CVL and their outcomes were generally favorable implying limited benefit of routine surveillance and thromboprophylaxis. Prospective research is needed to clarify the optimal management of iVTE.

Patient Blood Management in Pediatric Cardiac Surgery: A Review

Efforts to reduce blood product transfusions and adopt blood conservation strategies for infants and children undergoing cardiac surgical procedures are ongoing. Children typically receive red blood cell and coagulant blood products perioperatively for many reasons, including developmental alterations of their hemostatic system, and hemodilution and hypothermia with cardiopulmonary bypass that incites inflammation and coagulopathy and requires systemic anticoagulation. The complexity of their surgical procedures, complex cardiopulmonary interactions, and risk for inadequate oxygen delivery and postoperative bleeding further contribute to blood product utilization in this vulnerable population. Despite these challenges, safe conservative blood management practices spanning the pre-, intra-, and postoperative periods are being developed and are associated with reduced blood product transfusions. This review summarizes the available evidence regarding anemia management and blood transfusion practices in the perioperative care of these critically ill children. The evidence suggests that adoption of a comprehensive blood management approach decreases blood transfusions, but the impact on clinical outcomes is less well studied and represents an area that deserves further investigation.

Venous thromboembolism in chronic pediatric heart disease is associated with substantial health care burden and expenditures

ABSTRACT

Background: Venous thromboembolism (VTE) is a complication in children with chronic pediatric heart disease (CPHD). The influence of acute VTE risk factors and the health care burden associated with VTE in CPHD is unknown.Methods: Children <18 years of age with a CPHD diagnostic code were identified from the 2003-2013 MarketScan Commercial Databases. VTE diagnoses were identified either concomitantly with initial CPHD diagnoses or during a 6-month follow-up. The associations between demographic and clinical characteristics and VTE among children with CPHD, stratified by recent cardiac surgery, were assessed by multivariable logistic regression models. Estimates of health care utilization were compared using Wilcoxon rank-sum tests.Results: VTE events occurred in 957 of 120 884 children with CPHD (0.8%). In-hospital mortality was significantly higher in children with VTE. Single-ventricle physiology had the highest VTE rate (2.3%). All comorbid conditions were significantly associated with VTE, but the prevalence was highest in children with recent cardiac (11.1%) or noncardiac surgery (7.8%). The magnitude of association between noncardiac comorbidities and acquired acute cardiovascular conditions and VTE were larger for children without a recent cardiac surgery. Children with VTE had significantly higher health care utilization.Conclusions: VTE in CPHD is associated with significantly increased health care resource utilization and in-hospital mortality. All of the comorbid conditions examined were significantly associated with VTE, but a recent surgical procedure, especially cardiac surgery, conferred the highest VTE risk. Although confounding inherently limits observational studies, these findings provide practical information about the health care costs among patients with CPHD and VTE.

Analysis of Patient Characteristics and Risk Factors for Thrombosis After Surgery for Congenital Heart Disease

OBJECTIVES

Thrombosis is a cause of morbidity in 4-15% of children who undergo pediatric cardiac surgery. Data on how to prevent this complication are sorely needed. We aimed to identify risk factors for thrombosis following pediatric cardiac surgery and determine if use of low molecular weight heparin prophylaxis is associated with a reduction in thrombosis risk.

DESIGN

Retrospective cohort study.

SETTING

Tertiary pediatric cardiovascular ICU.

PATIENTS

Patients who underwent cardiac surgery between June 2014 and December 2015.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Data from patients with venous or arterial thrombosis confirmed by radiologic studies were matched two-to-one to controls based on age, Society of Thoracic Surgeons-European Association for Cardio-Thoracic Surgery mortality category, and gender. Thrombosis was detected in 33 patients (6.2%): 25 patients (76%) had venous thromboses, five patients (15%) had arterial thromboses, and three patients (9%) had both. Median time to thrombosis detection was 13 days (25-75%; 7-31 d). On multivariate analysis, which included adjustment for postoperative disease severity, fresh frozen plasma exposure was independently associated with thrombosis (odds ratio, 3.7; 95% CI, 1.4-9.4). Twenty-eight patients (85%) had central venous catheter-related thromboses. Low molecular weight heparin prophylaxis use in this subset of patients was not statistically different from controls (50% vs 45%, respectively; p = 0.47). On multivariable analysis, fresh frozen plasma exposure was also independently associated with central venous catheter-related thrombosis (odds ratio, 3.6; 95% CI, 1.2-10.6).

CONCLUSIONS

The occurrence of thrombosis after pediatric cardiac surgery at our institution was 6.2%, similar to what has been reported in other studies, despite frequent use of low molecular weight heparin. Further study is needed to determine the role of low molecular weight heparin for thromboprophylaxis and the relationship between fresh frozen plasma and thrombosis risk in children who undergo cardiac surgery.

The natural history of asymptomatic central venous catheter-related thrombosis in critically ill children

Asymptomatic central venous catheter (CVC)-related thrombosis in children varies in incidence from 5% to 69%. The rate of acute and long-term complications, such as postthrombotic syndrome (PTS), from asymptomatic CVC-related thrombosis is unknown. This article reports the outcomes of a prospective study of 189 children in pediatric intensive care that aimed to determine the frequency of asymptomatic CVC-related thrombosis during hospital admission, and the incidence of residual CVC-related thrombosis and clinically significant PTS 2 years later. Risk factors associated with CVC-related thrombosis were also identified. This study is distinct from previous work as children identified to have asymptomatic CVC-related thrombosis were not treated (clinical team kept blinded) and the entire cohort was followed for 2 years to determine the natural history of asymptomatic thrombosis. Ultrasounds of 146 children determined a 21.9% incidence of acute CVC-related thrombosis. Two children were symptomatic. No radiological thrombosis extension or clinical embolization occurred in the 126 children assessed at follow-up. Using 2 recognized PTS scales, clinically significant PTS was reported in 2 children (1 symptomatic, 1 asymptomatic CVC-related thrombosis), however, neither had functional impairment. Cardiac arrest was a risk factor for CVC-related thrombosis during admission and femoral CVC placement was predictive of residual thrombosis 2 years later. This study challenges the notion that critically ill children with asymptomatic CVC-related thrombosis require anticoagulant treatment, as the results demonstrate that the incidence of acute or long-term complications is low. A larger confirmatory study of nontreatment of CVC-related thrombosis in critically ill children is justified.

Double-Blind, Randomized, Placebo-Controlled Trial Comparing the Effects of Antithrombin Versus Placebo on the Coagulation System in Infants with Low Antithrombin Undergoing Congenital Cardiac Surgery

OBJECTIVES

To determine whether precardiopulmonary bypass (CPB) normalization of antithrombin levels in infants to 100% improves heparin sensitivity and anticoagulation during CPB and has beneficial effects into the postoperative period.

DESIGN

Randomized, double-blinded, placebo-controlled prospective study.

SETTING

Multicenter study performed in 2 academic hospitals.

PARTICIPANTS

The study comprised 40 infants younger than 7 months with preoperative antithrombin levels <70% undergoing CPB surgery.

INTERVENTIONS

Antithrombin levels were increased with exogenous antithrombin to 100% functional level intraoperatively before surgical incision.

MEASUREMENTS AND MAIN RESULTS

Demographics, clinical variables, and blood samples were collected up to postoperative day 4. Higher first post-heparin activated clotting times (sec) were observed in the antithrombin group despite similar initial heparin dosing. There was an increase in heparin sensitivity in the antithrombin group. There was significantly lower 24-hour chest tube output (mL/kg) in the antithrombin group and lower overall blood product unit exposures in the antithrombin group as a whole. Functional antithrombin levels (%) were significantly higher in the treatment group versus placebo group until postoperative day 2. D-dimer was significantly lower in the antithrombin group than in the placebo group on postoperative day 4.

CONCLUSION

Supplementation of antithrombin in infants with low antithrombin levels improves heparin sensitivity and anticoagulation during CPB without increased rates of bleeding or adverse events. Beneficial effects may be seen into the postoperative period, reflected by significantly less postoperative bleeding and exposure to blood products and reduced generation of D-dimers.

Increasing rates of thrombosis in children with congenital heart disease undergoing cardiac surgery

OBJECTIVE

To determine thrombosis incidence, morbidities, and mortality of children with congenital heart disease who develop thrombosis after cardiac surgery.

MATERIALS AND METHODS

This retrospective study reviewed patients <18 years old within the Pediatric Health Information System (PHIS) database who underwent cardiac surgery from 2004-2012. Thrombosis rates were compared for each procedure. Mortality was modeled using proportional hazards, adjusting for important clinical and demographic factors.

RESULTS

Of 91909 CHD patients who underwent surgery, 2655 (2.9%) developed thrombosis within the ensuing 12 months. The rate of thrombosis increased 253% (p<0.001), from 1.7% in 2004 to 4.4% in 2012. Systemic to pulmonary shunt placement (34.3%) and septostomy (26.1%) had the highest thrombosis percentages. Children <28 days had the highest prevalence (61%). Those with thrombosis had longer lengths of stay than those without [median 27 hospital days and 10 ICU days vs. 6 and 2 (p<0.001)]. Mean risk-adjusted cost was higher with thrombosis; $126,257 vs. $40,773 (p<0.001). Thrombosis was also associated with higher rates of bacteremia [8.3% vs. 3.4%, p<0.001], endocarditis [0.7% vs. 0.2%, p<0.001], and mortality [12.3% vs. 0.8%, p<0.001]. The adjusted hazard ratio for mortality in patients with thrombosis was 5.5 (95% CI: 4.6-6.5).

CONCLUSIONS

Thrombosis rates in CHD patients after cardiac surgery is increasing. Thrombosis is associated with longer hospital stay, increased ICU days, and cost. CHD patients with thrombosis also have increased bacteremia and mortality rates. More research is needed to understand contributors to thrombosis which may help develop strategies to mitigate morbidity and mortality.

Risk Factors, Prophylaxis, and Treatment of Venous Thromboembolism in Congenital Heart Disease Patients

Congenital heart disease (CHD) is a common condition in the pediatric population, affecting up to 1% of all live births (i.e., around 40,000 newborns/year in the United States). Although CHD does have a wide range of severity, by the age of 5 years approximately 80% of patients will require at least one surgical intervention to achieve a complete/palliative cardiac repair. Today, in light of their much-improved surgical survival, the care of these patients focuses on morbidity prevention and/or treatment. One such morbidity has been the increased frequency of thrombotic occlusions [e.g., cardioembolic arterial ischemic strokes; arterial, cardiac, and/or newly created shunt thrombosis; venous thromboembolism (VTE)]. Patients with CHD are at high risk of developing thrombosis due to the disruption of blood flow, CHD-related coagulopathy, inflammation, and/or platelet activation secondary to extracorporeal circulation support required during open-heart surgery or as a bridge to recovery, which can increase thrombus formation. In this article, we will discuss how the coagulation system is altered in patients with CHD in regard to the patient's anatomy, procedures they undergo to correct their congenital heart defect, and other risk factors that may increase their thrombotic risk, focusing on VTE. We will also discuss the most recently published reports pertaining to guidelines on prophylaxis and treatment of VTE in this population. Finally, we will briefly address the long-term VTE outcomes for patients with CHD.

AngioJet™ thrombolysis of SVC thrombosis after orthotopic heart transplantation: A case report

SVC obstruction is a rare acute complication after bicaval cardiac transplantation and can be catastrophic for the patient. Herein, we report the case of a child who developed SVC thrombosis causing acute SVC syndrome nine days after heart transplantation. Thrombolysis was successfully performed using the AngioJet^™ system and subsequent balloon angioplasty with re-establishment of flow. This procedure allowed for revascularization without repeat sternotomy or stent implantation. The patient is well without recurrence at last follow-up.

AngioJet rheolytic thrombectomy in a neonate with pulmonary artery thrombus

A newborn infant with obstructed supracardiac total anomalous pulmonary venous return underwent emergent surgical correction on day of life 0. A surgically placed transthoracic pulmonary artery catheter was used to monitor pulmonary artery pressure and removed on postoperative day 3. Following acute deterioration in respiratory status requiring reintubation, echocardiographic assessment demonstrated findings consistent with pulmonary hypertension and diminished flow to the left lung. Cardiac catheterization confirmed elevated pulmonary artery pressure and near complete occlusion of his left pulmonary artery due to a thrombus. He underwent successful percutaneous catheter-based thrombectomy using the AngioJet rheolytic catheter, recovered fully, and was discharged home on postoperative day 30. Although thrombotic events resulting in respiratory and hemodynamic compromise are rare in infants, recognition is important and treatment using mechanical thrombectomy can be life saving.

Prospective study of the incidence and predictors of thrombus in children undergoing palliative surgery for single ventricle physiology

PURPOSE

To determine the incidence and clinical and biomarker predictors of perioperative thrombosis in children with single ventricle physiology undergoing staged palliation.

METHODS

Nineteen patients were enrolled and 16 completed the study. Serial ultrasounds of the central venous system were performed to evaluate for thrombus. Plasma antithrombin III, thrombin-antithrombin complex, protein C, protein S, tissue factor pathway inhibitor, plasminogen activator inhibitor-1, tissue plasminogen activator antigen, D-dimer, soluble CD40 ligand, and urinary thromboxane were measured serially before and after surgery. Cardiopulmonary bypass time, aortic cross clamp time, blood product administration, inotrope score, chest tube output, cardiac function by echocardiography, intensive care unit and hospital lengths of stay, and central venous catheter days were recorded.

RESULTS

The incidence of perioperative thrombus was 31%. Patients who developed a thrombus had poorer preoperative ventricular function (p = 0.03) and longer cardiopulmonary bypass times (p = 0.03) than those who did not develop a thrombus. Preoperative plasma antithrombin III was lower (p = 0.01) and tissue plasminogen activator antigen concentrations were higher (p = 0.02) in patients with a thrombus compared with patients without a thrombus. When measured over time, antithrombin III remained lower (p = 0.002) and tissue plasminogen activator antigen higher (p = 0.005) in those who developed a thrombus compared with those who did not. There were no other statistically significant differences in biomarkers of coagulation between patients with and without thrombosis.

CONCLUSION

One-third of patients undergoing palliative surgery for single ventricle physiology develop thrombosis. Decreased ventricular function, low antithrombin III, and increased tissue plasminogen activator may predict those most suitable for randomized clinical trials of anticoagulation.

Risk, clinical features, and outcomes of thrombosis associated with pediatric cardiac surgery

BACKGROUND

Thrombosis, usually considered a serious but rare complication of pediatric cardiac surgery, has not been a major clinical and/or research focus in the past.

METHODS AND RESULTS

We noted 444 thrombi (66% occlusive, 60% symptomatic) in 171 of 1542 surgeries (11%). Factors associated with increased odds of thrombosis were age <31 days (odds ratio [OR], 2.0; P=0.002), baseline oxygen saturation <85% (OR, 2.0; P=0.001), previous thrombosis (OR, 2.6; P=0.001), heart transplantation (OR, 4.1; P<0.001), use of deep hypothermic circulatory arrest (OR, 1.9 P=0.01), longer cumulative time with central lines (OR, 1.2 per 5-day equivalent; P<0.001), and postoperative use of extracorporeal support (OR, 5.2; P<0.001). Serious complications of thrombosis occurred with 64 of 444 thrombi (14%) in 47 of 171 patients (28%), and were associated with thrombus location (intrathoracic, 45%; extrathoracic arterial, 19%; extrathoracic venous, 8%; P<0.001), symptomatic thrombi (OR, 8.0; P=0.02), and partially/fully occluding thrombi (OR, 14.3; P=0.001); indwelling access line in vessel (versus no access line) was associated with lower risk of serious complications (OR, 0.4; P=0.05). Thrombosis was associated with longer intensive care unit (+10.0 days; P<0.001) and hospital stay (+15.2 days; P<0.001); higher odds of cardiac arrest (OR, 4.9; P<0.001), catheter reintervention (OR, 3.3; P=0.002), and reoperation (OR, 2.5; P=0.003); and increased mortality (OR, 5.1; P<0.001). Long-term outcome assessment was possible for 316 thrombi in 129 patients. Of those, 197 (62%) had resolved at the last follow-up. Factors associated with increased odds of thrombus resolution were location (intrathoracic, 75%; extrathoracic arterial, 89%; extrathoracic venous, 60%; P<0.001), nonocclusive thrombi (OR, 2.2; P=0.01), older age at surgery (OR, 1.2 per year; P=0.04), higher white blood cell count (OR, 1.1/10(9) cells per 1 mL; P=0.002), and lower fibrinogen (OR, 1.4/g/L; P=0.02) after surgery.

CONCLUSIONS

Thrombosis affects a high proportion of children undergoing cardiac surgery and is associated with suboptimal outcomes. Increased awareness and effective prevention and detection strategies are needed.

Thrombotic events after pediatric liver transplantation

TE may contribute to morbidity and mortality after LT. The objectives were to determine the incidence of early TE post-pediatric LT and compare differences between children with and without TE. A retrospective review of 88 transplanted children (January 2002-October 2007) was performed to determine the incidence of Doppler-confirmed DVT and ATE in the first month post-LT. Fourteen (16%) patients developed TE: DVT in seven (8%) and ATE in seven (8%) patients. Six of 88 (6.8%) developed symptomatic CVL-related DVT. Median (range) time post-LT to DVT and ATE were 7 (4-18) and 8 (1-31) days, respectively. There was no significant difference in age/body weight at LT between patients with or without DVT and ATE. There was no significant difference between patients with or without HAT in age and weight at LT, cold ischemic time, duration of surgery, hematocrit levels, whole-organ graft type, intraoperative FFP, high-risk CMV status, or early acute cellular rejection. In conclusion, the incidence of early TE post-pediatric LT was 16%, including DVT in 8%. Prospective studies are necessary to evaluate the role of prophylactic anticoagulation and potential modifiable risk factors post-pediatric LT.

Frequency, predictors, and neurologic outcomes of vaso-occlusive strokes associated with cardiac surgery in children

OBJECTIVE

Our aim was to define the frequency, predictors, and outcomes of stroke associated with cardiac surgery in children with congenital heart disease.

METHODS

We performed a case-control study of children (term birth to 18 years) with congenital heart disease who underwent cardiac surgery at the Hospital for Sick Children between January 1, 1992, and March 1, 2001. Case subjects experienced stroke within 72 hours after cardiac surgery, and control subjects (2 for each case subjects) had cardiac surgery and no stroke. The frequency of arterial ischemic stroke/cerebral sinovenous thrombosis was calculated among children who underwent cardiac surgery during the study period. Predictors for stroke, including age, gender, simple versus complex procedure, reoperation, bypass duration, circulatory arrest, postoperative hematocrit level, and intraoperative activated clotting time, were tested. The presence of clinical and radiologically defined stroke was the main outcome. Neurologic outcomes were assessed in case subjects with the Pediatric Stroke Outcome Measure.

RESULTS

During the study period, 30 children with stroke (28 with arterial ischemic stroke and 2 with cerebral sinovenous thrombosis) were identified among 5526 children undergoing cardiac surgery. This yielded a risk for arterial ischemic stroke/cerebral sinovenous thrombosis of 5.4 strokes per 1000 children undergoing a cardiac operation. Univariate analysis revealed that older age at the time of the procedure, longer duration of cardiopulmonary bypass, number of days in the hospital postoperatively, and reoperation were associated with stroke. In multivariate analyses, only reoperation was associated with stroke.

CONCLUSIONS

The frequency of vaso-occlusive stroke in children with congenital heart disease undergoing cardiac surgery was 5.4 cases per 1000 children. Age, duration of bypass, and reoperation may be associated with stroke risk.

Postoperative chylothorax development is associated with increased incidence and risk profile for central venous thromboses

This study tested the hypothesis that pediatric patients who develop chylothorax (CTX) after surgery for congenital heart disease (CHD) have an elevated incidence and risk profile for central venous thrombosis (CVT). We evaluated 30 patients who developed CTX after surgery for CHD. All but one CTX patient were surgery-, anatomy-, and age-matched with two controls (NON-CTX) to compare their relative risk and incidence of CVT. Using conditional logistic regression analyses, CTX development was associated with significantly longer ventilator dependence (14.8 +/- 10.9 vs. 6.1 +/- 5.9 days, p = 0.003) and a non-significant trend towards more days of central venous catheters (CVC) (19.1 +/- 16.6 vs. 12.2 +/- 10.0 days; p = 0.16) when comparing the period prior to CTX development with the entire hospitalization in NON-CTX patients. CTX development was associated with a significantly elevated mortality risk (Odds Ratio 6.2, 95% CI 1.3-30.9). Minimum and mean daily central venous pressures were significantly higher in the CTX group. Post operative need for extracorporeal membrane oxygenation conferred an increased risk of CTX development in this sample of patients (Odds Ratio 9.9, 95% CI 2.2-44.8). Incidence of documented CVT was 26.7% in the CTX group versus 5.1% in the NON-CTX group. Prospective screening for CVT risk and formation, combined with early removal of CVC may help reduce the incidence of CTX.

Low Arterial Saturation Is Associated With Increased Sensitivity to Activated Protein C in Children With Congenital Heart Disease

OBJECTIVES

Children with congenital heart disease experience both hemorrhagic and thrombotic complications. In this report the authors test the hypothesis that hypoxemia is associated with altered sensitivity to activated protein C (aPC) in pediatric patients with congenital heart lesions.

DESIGN

A retrospective genetic registry review, with statistical evaluation of factors contributing to the aPC ratio.

SETTING

Large university hospital.

PARTICIPANTS

Cohort of 92 children with congenital heart disease undergoing cardiac catheterization procedures.

INTERVENTIONS

The authors measured the aPC ratio at cardiac catheterization and evaluated the contribution of independent variables using linear regression and classification tree approaches. Independent variables included age, gender, use of aspirin, history of thrombosis, room air arterial saturation, factor VIII:C levels, presence of congestive heart failure, and heterozygosity for factor V Leiden.

MEASUREMENTS AND MAIN RESULTS

At univariate analysis, factor V Leiden, female gender, room air arterial saturation, age greater than 6 months, and plasma factor VIII:C levels were associated with a lower aPC ratio (resistance to aPC). At stepwise linear regression, arterial saturation, factor VIII:C level, female gender, and factor V Leiden were independently associated with a lower aPC ratio, and these variables explained about 49% of the variability in aPC ratio. The classification tree approach confirmed the dependence of aPC ratio on factor V genotype and arterial saturation.

CONCLUSIONS

The aPC ratio in this population is associated with hypoxemia, independent of factors previously observed in adults. Further studies are under way to determine how aPC resistance or sensitivity may independently affect perioperative hemostasis in this population.

A noninvasive estimation of mixed venous oxygen saturation using near-infrared spectroscopy by cerebral oximetry in pediatric cardiac surgery patients

BACKGROUND

Near-infrared spectroscopy (NIRS) is a noninvasive optical monitor of regional cerebral oxygen saturation (rSO2). The aim of this study was to validate the use of NIRS by cerebral oximetry in estimating invasively measured mixed venous oxygen saturation (SvO2) in pediatric postoperative cardiac surgery patients.

METHODS

Twenty patients were enrolled following cardiac surgery with intraoperative placement of a pulmonary artery (PA) or superior vena cava (SVC) catheter. Five patients underwent complete biventricular repair--complete atrioventricular canal (n=3) and other (n=2). Fifteen patients with functional single ventricle underwent palliative procedures--bidirectional Glenn (n=11) and Fontan (n=4). Cerebral rSO2 was monitored via NIRS (INVOS 5100) during cardiac surgery and 6 h postoperatively. SvO2 was measured from blood samples obtained via an indwelling PA or SVC catheter and simultaneously correlated with rSO2 by NIRS at five time periods: in the operating room after weaning from cardiopulmonary bypass, after sternal closure, and in the CICU at 2, 4, and 6 h after admission.

RESULTS

Each patient had five measurements (total=100 comparisons). SvO2 obtained via an indwelling PA or SVC catheter for all patients correlated with rSO2 obtained via NIRS: Pearson's correlation coefficient of 0.67 (P<0.0001) and linear regression of r2=0.45 (P<0.0001). Separate linear regression of the complete biventricular repairs demonstrated an r=0.71, r2=0.50 (P<0.0001). Bland-Altman analysis showed a bias of +3.3% with a precision of 16.6% for rSO2 as a predictor of SvO2 for all patients. Cerebral rSO2 was a more accurate predictor of SvO2 in the biventricular repair patients (bias -0.3, precision 11.8%), compared with the bidirectional Glenn and Fontan patients.

CONCLUSIONS

Regional cerebral oximetry via NIRS correlates with SvO2 obtained via invasive monitoring. However, the wide limits of agreement suggest that it may not be possible to predict absolute values of SvO2 for any given patient based solely on the noninvasive measurement of rSO2. Near-infrared spectroscopy, using the INVOS 5100 cerebral oximeter, could potentially be used to indicate trends in SVO2, but more studies needs to be performed under varying clinical conditions.

The response to activated protein C after cardiopulmonary bypass: impact of factor V leiden

Activated protein C (aPC) resistance is a recognized hypercoagulable phenotype that is associated with increased risk for thrombosis in multiple clinical settings. Factor V Leiden (FVL) represents a specific inherited cause of aPC resistance, but the perioperative thrombotic risk of FVL is unclear. In this investigation, we sought to quantify whether cardiopulmonary bypass produces alterations in aPC resistance in FVL carriers and noncarrier controls, testing the hypothesis that FVL is associated with a relatively hypercoagulable postoperative state. Two-hundred-five adult cardiac surgery patients were prospectively enrolled into a genetic registry whose purpose was to study the impact of genetic variables on clinical outcomes. For this study, 8 subjects heterozygous for FVL were identified (group L), as well as 2 control groups: group MC, matched controls, 18 matched subjects without FVL; and group UC, unmatched controls, 11 consecutive subjects without FVL. Plasma was sampled at the beginning of surgery, 10 min after protamine administration, and on postoperative day 1, and assayed for resistance to aPC (normal aPC ratio is >2.0). Both MC and UC groups exhibited normal aPC ratio at baseline (2.40 and 2.36, respectively), which increased significantly (to 2.76 and 2.75, P = 0.007 and 0.021, respectively) on postoperative day 1, indicating increased postoperative sensitivity to aPC. Conversely, group L subjects exhibited aPC resistance at baseline (aPC ratio 1.80), and did not change significantly postoperatively (P = 0.867). Patients without FVL therefore show laboratory evidence consistent with relative protection from postoperative thrombosis, whereas FVL carriers do not. These findings provide mechanistic support for previous speculations of increased postoperative thrombotic risk associated with FVL.

Factor V Leiden and perioperative risk

Factor V Leiden (FVL) is the most common known inherited cause of thrombophilia; it is present in approximately 5% of the Caucasian population. Although the risk of venous thrombosis associated with this polymorphism in various medical settings is well described, its effect on perioperative risk is only beginning to be explored. Specifically, there are few studies addressing the potential risks of FVL in the surgical population, in which both hemorrhagic and thrombotic complications convey substantial clinical and economic significance. There are speculations and unproven hypotheses regarding FVL in this population, and these therefore highlight the need to comprehensively address this issue. This review will describe the physiology of the FVL mutation, briefly clarify its risk in the nonsurgical setting, and assess current data regarding FVL in noncardiac and cardiac surgery. Finally, a summary of current clinical evidence and a plan for more detailed investigation of this potentially significant risk factor will be proposed.

The risk of postthrombotic syndrome in children with congenital heart disease

The lower extremities of 28 unselected children with congenital heart disease were investigated and classified according to the criteria for postthrombotic syndrome five to ten years after their first cardiac catheterization. For the clinical criteria, all patients completed a questionnaire and underwent a standardized physical examination of both legs. For the pathophysiologic criteria, the presence of venous outflow obstruction and reflux was evaluated by color duplex sonography in 24 of the 28 patients. Mild postthrombotic syndrome was present in half the patients. Partial or complete occlusion of the investigated vein was found in four patients (17%). In all patients studied, the venous valves of the deep system were competent. Postthrombotic syndrome frequently occurs in children with congenital heart disease. Prospective studies seem to be justified to investigate the precise incidence and potential risk factors.

Transcatheter management of innominate vein thrombosis prior to bidirectional cavopulmonary anastomosis

Innominate vein thrombosis was diagnosed in an 8-months-old infant after stage I surgery for hypoplastic left heart syndrome. Cardiac catheterization identified venous collaterals bypassing the innominate vein via the azygous vein. Coil occlusion of the distal azygous vein allowed a subsequent cavopulmonary anastomosis directing collateral flow into the pulmonary bed. Cathet. Cardiovasc. Intervent. 49:61-63, 2000.

Prothrombotic abnormalities in children with venous thromboembolism

PURPOSE

The aim of this study was to determine the frequency of acquired or inherited prothrombotic disorders in a pediatric population with venous thromboembolism (VTE).

PATIENTS AND METHODS

From May 1992 to April 1998, 56 consecutive children with VTE were prospectively studied at a single center.

RESULTS

The median age was 8.4 years (range, 0.1-18 years). There was a male predominance. Fifty (89%) children had thrombosis in the lower venous system. Risk factors were detected in 54 (96%) children. Twenty-one (38%) thrombotic episodes were related to central venous lines. Family history of thrombosis was positive in 13 (23%) patients. In 26 (46%) patients, a prothrombotic disorder was detected. Nine of them had inherited disorders (protein C deficiency, 5 patients; protein S deficiency, 3 patients; Factor V Leiden mutation, 1 patient), and 13 children had acquired disorders (antiphospholipid antibodies, 5 patients; antithrombin deficiency, 8 patients). The remaining four showed combined abnormalities (Factor V Leiden mutation associated with inherited protein S deficiency, 1 patient; acquired antithrombin deficiency, 2 patients and inherited antithrombin deficiency, 1 patient).

CONCLUSIONS

In the series, a high percentage of prothrombotic disorders was detected; thus, a complete hemostatic evaluation should be performed in all of the children with VTE whether the patients have one or more risk factors.

Upregulation of the antithrombotic protein C pathway at birth

Serious thrombotic complications occur in sick neonates, while healthy infants have a very low risk of thrombosis. To better understand the regulation of physiological anticoagulation at birth, components of the protein C pathway were measured in cord plasma samples from 14 full-term healthy newborns and in samples from 10 adult controls. Although zymogen protein C was significantly reduced in cord plasma (mean +/- SEM in cord vs. adult sample 37 +/- 1.4% vs. 90 +/- 5.5%, p < 0.0001), levels of the active enzyme, activated protein C (APC), were not (119 +/- 20% vs. 75 +/- 12%, p = 0.0762). Relative to the protein C level, cord plasmas had a 5.2-fold higher APC level (p < 0.01). The APC increase was partially due to slower inactivation of APC in cord plasma (half-life for APC 50 min in cord plasma vs. 27 minutes in adult plasma). Increased sensitivity of factor V to inactivation by APC in cord plasma was observed since the activated partial thromboplastin time-based APC sensitivity ratio was significantly increased for cord vs. adult plasma samples (2.28 +/- 0.09 versus 1.97 +/- 0.03, p < 0.01). Thus, despite low zymogen protein C, the protein C pathway in newborns seems to be functionally well developed and at an activated stage at birth.

Late vascular occlusion of central lines in pediatric malignancies

OBJECTIVE

To determine whether thrombi or vascular occlusion represent a late complication persisting several years after removal of central venous lines (CVLs) in children and adolescents treated for childhood cancer.

METHODS

Children whose treatment for malignancy included placement of a CVL that had been removed at least 2 months previously were studied during scheduled follow-up that included contrast-enhanced computed tomography. Spiral volume acquisition was used to obtain 3-mm images from the chest apices through the right hilum, and three-dimensional reconstruction of angiograms was performed. Thrombosis/occlusion was defined as narrowing, obstruction, or filling defect of the deep venous system, with or without the formation of collateral veins. Charts were reviewed to document patient characteristics, previous CVL complications, administration of hyperalimentation, use of urokinase, and family history of venous thrombosis.

RESULTS

Twenty-three patients treated for solid tumors and 2 treated for B-cell acute lymphocytic leukemia or lymphoma were studied. Lines had been in place from 0.2 to 36 months (median, 7.4) and were removed at 2.3 to 121.8 months (median, 32.5) before study. Nine patients received hyperalimentation for periods ranging from 2 to 38 weeks (median, 12). Four patients had required urokinase instillations, and one developed superior vena cava syndrome; 4 had a CVL-related infection (two superficial and two Candida line infections). Occlusion was seen on computed tomography angiograms in 3 of the 25 patients (12%; 95% confidence interval: 4.5-31%). One of the patients with occlusion had superior vena cava syndrome; none had a family history of thrombosis, use of a double lumen CVL, or multiple instillations of urokinase.

CONCLUSIONS

Persistent asymptomatic vascular occlusion does occur as a late complication of CVL placement for treatment of childhood malignancies, although the frequency appears low among patients treated primarily for solid tumors. Prospective studies of large numbers of patients with a broader spectrum of diagnoses are necessary to define the incidence of and risk factors for this complication and to assess the need for prevention with anticoagulation or other therapy. Pediatricians caring for patients with a history of cancer and CVLs should be aware that these patients may have persistent vascular occlusion that could predispose them to recurrent thrombosis or postphlebitic syndrome.