Nutritional markers accompanying acquired chylothorax in infants: a systematic review.

CONTEXT: Chylothorax is a well-established acquired complication of thoracic surgery in infants. Current data suggest acquired chylothorax may affect infant growth and nutrition because of a loss of essential nutrients via chylous effusion. OBJECTIVE: The 3 objectives for this study were: (1) identify nutritional markers affected by the development of acquired chylothorax in infants; (2) highlight the variability in methods used to assess nutritional status and growth in this patient population; and (3) highlight nutritional deficits that can serve as treatment targets during postoperative feeding protocols. DATA SOURCES: A systematic literature search was conducted between May 31, 2021, and June 21, 2022, using the PubMed, Embase, CINAHL, and Web of Science databases. Search terms included, but were not limited to, "chylothorax," "infants," and "nutrition." DATA EXTRACTION: Inclusion criteria required studies that measured quantitative markers of nutrition in ≥10 participants aged <1 year with acquired chylothorax. A total of 575 studies were screened and all but 4 were eliminated. Nutritional markers were categorized into 4 different groups: total serum protein level, triglyceride levels, growth velocity, and weight for length. DATA ANALYSIS: The variation in methods, time points, interventional groups, and nutritional markers did not facilitate a meta-analysis. Risk of bias was assessed using the Cochrane Risk of Bias in Nonrandomized Studies assessment tool. CONCLUSION: This review highlights the need for reliable quantitative markers of nutrition that will enable providers to assess the nutritional needs of infants with chylothorax. Future studies must focus on measuring markers of nutrition at regular intervals in larger study populations.

Successful Surgical Management of Aortic Arch Thrombosis in the Neonate.

Spontaneous thrombosis in the aortic arch is a rare finding in the neonate. Often the thrombosis is initially interpreted as arch obstruction secondary to coarctation or interrupted aortic arch. Thus the obstruction is mechanical with no structural abnormality. We describe 2 newborns with coarctation and extensive thrombosis within the aortic arch. We report their successful surgical management, with a brief review of the literature and pertinent management principles.

Changes in tissue oxygen tension, venous saturation, and Fick-based assessments of cardiac output during hyperoxia.

BACKGROUND: Hyperoxemia (arterial oxygen tension >100 mm Hg) may occur in critically ill patients and have effects on mixed venous saturation (SvO2 ) and on Fick-based estimates of cardiac output (CO). We investigated the effect of hyperoxemia on SvO2 and on assessments of CO using the Fick equation. METHODS: Yorkshire swine (n = 14) were anesthetized, intubated, and paralyzed for instrumentation. SvO2 (co-oximetry) and tissue oxygen tension (tPO2 , implantable electrodes) in brain and myocardium were measured during systematic manipulation of arterial oxygen tension (PaO2 ) using graded hyperoxia (fraction of inspired oxygen 0.21 → 0.8). Secondarily, oxygen- and carbon dioxide-based estimates of CO (FickO2 and FickCO2 , respectively) were compared with measurements from a flow probe placed on the aortic root. RESULTS: Independent of changes in measured oxygen delivery, cerebral and myocardial tPO2 increased in proportion to PaO2 , as did SvO2 (P < 0.001 for all). Based on mixed model analysis, each 100 mm Hg increase in PaO2 resulted in a 4.8 ± 0.9% increase in SvO2 under the conditions tested. Because neither measured oxygen consumption, arterial oxyhemoglobin saturation or cardiac output varied significantly during hyperoxia, changes in SvO2 resulted in successively increasing errors in FickO2 during hyperoxia (34% during normoxia, 72% during FiO2 0.8). FickCO2 lacked the progressively worsening errors present in FickO2 , but correlated poorly with CO. CONCLUSION: SvO2 acutely changes following changes in PaO2 even absent changes in measured DO2 . This may lead to errors in FickO2 estimates of CI. Further work is necessary to understand the impact of this phenomenon in disease states.

Towards Alternative Approaches for Coupling of a Soft Robotic Sleeve to the Heart.

Efficient coupling of soft robotic cardiac assist devices to the external surface of the heart is crucial to augment cardiac function and represents a hurdle to translation of this technology. In this work, we compare various fixation strategies for local and global coupling of a direct cardiac compression sleeve to the heart. For basal fixation, we find that a sutured Velcro band adheres the strongest to the epicardium. Next, we demonstrate that a mesh-based sleeve coupled to the myocardium improves function in an acute porcine heart failure model. Then, we analyze the biological integration of global interface material candidates (medical mesh and silicone) in a healthy and infarcted murine model and show that a mesh interface yields superior mechanical coupling via pull-off force, histology, and microcomputed tomography. These results can inform the design of a therapeutic approach where a mesh-based soft robotic DCC is implanted, allowed to biologically integrate with the epicardium, and actuated for active assistance at a later timepoint. This strategy may result in more efficient coupling of extracardiac sleeves to heart tissue, and lead to increased augmentation of heart function in end-stage heart failure patients.

An Implantable Extracardiac Soft Robotic Device for the Failing Heart: Mechanical Coupling and Synchronization.

Soft robotic devices have significant potential for medical device applications that warrant safe synergistic interaction with humans. This article describes the optimization of an implantable soft robotic system for heart failure whereby soft actuators wrapped around the ventricles are programmed to contract and relax in synchrony with the beating heart. Elastic elements integrated into the soft actuators provide recoiling function so as to aid refilling during the diastolic phase of the cardiac cycle. Improved synchronization with the biological system is achieved by incorporating the native ventricular pressure into the control system to trigger assistance and synchronize the device with the heart. A three-state electro-pneumatic valve configuration allows the actuators to contract at different rates to vary contraction patterns. An in vivo study was performed to test three hypotheses relating to mechanical coupling and temporal synchronization of the actuators and heart. First, that adhesion of the actuators to the ventricles improves cardiac output. Second, that there is a contraction-relaxation ratio of the actuators which generates optimal cardiac output. Third, that the rate of actuator contraction is a factor in cardiac output.

Pseudoaneurysm complicating right ventricle-to-pulmonary artery conduit surgery: Incidence and risk factors.

OBJECTIVES: Although pseudoaneurysm is an uncommon complication after right ventricle-to-pulmonary artery conduit placement, it has the potential to cause significant morbidity and mortality. METHODS: We performed a review of patients with pseudoaneurysms diagnosed at our institution in a 20-year period (from 1995 through 2015) and compared their clinical characteristics with a group of age- and sex-matched control patients. RESULTS: We found that younger age, smaller size, the diagnosis of tetralogy of Fallot, the use of a pulmonary homograft conduit, the presence of an unrestrictive ventricular septal defect after conduit placement, and having at least systemic right ventricular pressure were all more common in patients who had pseudoaneurysms develop. CONCLUSIONS: This study is unique in identifying both patient and surgical factors that may predispose to pseudoaneurysm development and can help inform optimal strategies to monitor and evaluate this patient population.

The use of soft robotics in cardiovascular therapy.

INTRODUCTION: Robots have been employed in cardiovascular therapy as surgical tools and for automation of hospital systems. Soft robots are a new kind of robot made of soft deformable materials, that are uniquely suited for biomedical applications because they are inherently less likely to injure body tissues and more likely to adapt to biological environments. Awareness of the soft robotic systems under development will help promote clinician involvement in their successful clinical translation. Areas covered: The most advanced soft robotic systems, across the size scale from nano to macro, that have shown the most promise for clinical application in cardiovascular therapy because they offer solutions where a clear therapeutic need still exists. We discuss nano and micro scale technology that could help improve targeted therapy for cardiac regeneration in ischemic heart disease, and soft robots for mechanical circulatory support. Additionally, we suggest where the gaps in the technology currently lie. Expert commentary: Soft robotic technology has now matured from the proof-of-concept phase to successful animal testing. With further refinement in materials and clinician guided application, they will be a useful complement for cardiovascular therapy.

Management of Tricuspid Regurgitation in Patients With Hypoplastic Left Heart Syndrome.

Tricuspid valve (TV) performance is critical for palliation of hypoplastic left heart syndrome. We will review current TV repair techniques, outcomes, and novel approaches.

Soft robotic sleeve supports heart function.

There is much interest in form-fitting, low-modulus, implantable devices or soft robots that can mimic or assist in complex biological functions such as the contraction of heart muscle. We present a soft robotic sleeve that is implanted around the heart and actively compresses and twists to act as a cardiac ventricular assist device. The sleeve does not contact blood, obviating the need for anticoagulation therapy or blood thinners, and reduces complications with current ventricular assist devices, such as clotting and infection. Our approach used a biologically inspired design to orient individual contracting elements or actuators in a layered helical and circumferential fashion, mimicking the orientation of the outer two muscle layers of the mammalian heart. The resulting implantable soft robot mimicked the form and function of the native heart, with a stiffness value of the same order of magnitude as that of the heart tissue. We demonstrated feasibility of this soft sleeve device for supporting heart function in a porcine model of acute heart failure. The soft robotic sleeve can be customized to patient-specific needs and may have the potential to act as a bridge to transplant for patients with heart failure.

Phosphodiesterase Inhibitor-Based Vasodilation Improves Oxygen Delivery and Clinical Outcomes Following Stage 1 Palliation.

BACKGROUND: Systemic vasodilation using α-receptor blockade has been shown to decrease the incidence of postoperative cardiac arrest following stage 1 palliation (S1P), primarily when utilizing the modified Blalock-Taussig shunt. We studied the effects of a protocol in which milrinone was primarily used to lower systemic vascular resistance (SVR) following S1P using the right ventricular to pulmonary artery shunt, measuring its effects on oxygen delivery (DO2) profiles and clinical outcomes. We also correlated Fick-based assessments of DO2 with commonly used surrogate measures. METHODS AND RESULTS: Neonates undergoing S1P were treated according to best clinical judgment prior to (n=32) and following (n=24) implementation of a protocol that guided operative, anesthetic, and postoperative management, particularly as it related to SVR. A majority of the subjects (n=51) received a modified right ventricular to pulmonary artery shunt. In a subset of these patients (n=21), oxygen consumption (VO2) was measured and used to calculate SVR, DO2, and oxygen debt. Neonates treated with the protocol had significantly lower SVR (P=0.02), serum lactate (P<0.001), and Sa-vO2 difference (P<0.001) and a lower incidence of CPR requiring extracorporeal membrane oxygenation (E-CPR, P=0.02) within the first 72 postoperative hours. DO2 was closely associated with SVR (r2=0.78) but correlated poorly with arterial (SaO2) and venous (SvO2) oxyhemoglobin concentrations, the Sa-vO2 difference, and blood pressure. CONCLUSIONS: A vasodilator protocol utilizing milrinone following S1P effectively decreased SVR, improved serum lactate, and decreased postoperative cardiac arrest. DO2 correlated more closely with SVR than with Sa-vO2 difference, highlighting the importance of measuring VO2 in this population. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT02184169.

Outcome and performance of bioprosthetic pulmonary valve replacement in patients with congenital heart disease.

OBJECTIVES: The goal of this single-center series was to assess differences in reintervention by the type of valve used for surgical bioprosthetic pulmonary valve replacement and to identify independent predictors of reintervention. METHODS: Data were retrospectively collected for 611 patients undergoing pulmonary valve replacement from 1996 to 2014. Kaplan-Meier estimation and Cox proportional hazards regression methodologies were used. RESULTS: The median age of patients was 17.8 years (interquartile range, 11.9-27.3). The diagnosis was tetralogy of Fallot in 69% of patients. The median follow-up was 3.0 years (interquartile range, 1.1-5.3). Valve types included Sorin Mitroflow (Milan, Italy), 316 (50%; median age 16.5 years); Carpentier-Edwards (Irvine, Calif) Magna/MagnaEase, 223 (35%; median age, 19.3 years); and Carpentier-Edwards Perimount, 72 (11%; median age, 21.9 years). Reintervention occurred in 6.7% of patients (41/633) and was higher in children than adults (hazard ratio, 4.8). Age-adjusted 5-year reintervention rates were Sorin Mitroflow, 13.4%; Carpentier-Edwards Magna/MagnaEase, 2.1%; and Carpentier-Edwards Perimount, 0%. Reintervention was not associated with gender, valve insertion method, or concurrent procedures. The only independent risk factor for reintervention after controlling for age was valve type (P < .001). The Sorin Mitroflow valve had a shorter time to reintervention than the other 2 valve types (hazard ratios both >7, each P < .001). Differences by valve type did not depend on age (interaction P = .61). CONCLUSIONS: Bioprosthetic pulmonary valve replacement in patients with congenital heart disease has excellent short-term outcomes, but children have an approximately 5-fold greater risk of reintervention than adults. Independently of age, reintervention rates vary by valve type. These differences may be important in valve selection and follow-up.

Are Bioprosthetic Valves Appropriate for Aortic Valve Replacement in Young Patients?

Selection of a prosthetic aortic valve for use in the young patient is complicated by a variety of important considerations. Age, growth potential, activity and life style expectations, child bearing, and social factors, in addition to anatomic considerations, are all important to the recommendation of a prosthetic valve choice. We review the clinical experience and expectations of currently available prosthetic aortic valves available for the young patient, and describe the advantages and disadvantages for each.

Fractures Related to Metabolic Bone Disease in Children with Congenital Heart Disease.

OBJECTIVE: Critically ill children with congenital heart disease (CHD) are at risk for metabolic bone disease (MBD) and bone fractures. Our objective was to characterize a cohort of CHD patients with fractures and describe a Fragile Bone Protocol (FBP) developed to reduce fractures. DESIGN/SETTING: Patients who developed fractures in the Cardiac Intensive Care Unit (CICU) of Boston Children's Hospital from 3/2008 to 6/2014 were identified via quality improvement and radiology databases. The FBP (initiated July 2011) systematically identifies patients at risk for MBD and prescribes special handling precautions. RESULTS: Twenty-three fractures were identified in 15 children. Median age at fracture identification was 6.2 months, with a median duration of hospitalization before fracture diagnosis of 2.7 months. Six patients (40%) had single ventricle CHD. Hyperparathyroidism and low 25-OH vitamin D levels were present in 77% and 40% of those tested, respectively. Compared with patients not diagnosed with fractures, fracture patients had increased exposure to possible risk factors for MBD and had elevated parathyroid and decreased calcitriol levels.Six patients (40%) did not survive to hospital discharge, compared with an overall CICU mortality rate of 2.6% (P < .01). The fracture case rate before implementation of the FBP was 2.6 cases/1000 admissions and was 0.7/1000 after implementation of the FBP (P = .04). CONCLUSIONS: Critically ill CHD patients are at risk for fractures. They represent a complex group who frequently has hyperparathyroidism and decreased calcitriol levels, and each may predispose to fractures. FBPs consisting of identification and careful patient handling should be considered in at-risk patients.

Biventricular repair for common atrioventricular canal defect with parachute left atrioventricular valve.

OBJECTIVES: Parachute left atrioventricular (AV) valve can complicate repair of common atrioventricular canal (CAVC), and single-ventricle palliation is sometimes preferred. The goal of this study is to review our single institutional experience in biventricular repair in this patient group. METHODS: The demographic, procedural and outcome data were obtained for all children who underwent biventricular repair for complete CAVC with parachute [single left ventricular (LV) papillary muscle] or forme fruste parachute left AV valve (closely spaced LV papillary muscles) from 2001 to 2012. Primary outcomes were survival, freedom from left AV valve stenosis (defined as an inflow gradient ≥7 mmHg and post-capillary pulmonary hypertension) and freedom from left AV valve replacement. RESULTS: A total of 24 patients were included (21 parachutes, 3 forme frustes). There was 1 early death (4.2%). At discharge, no patient had more-than-mild regurgitation and 1 had stenosis. During a median follow-up of 3.7 years (IQR 4 months to 5 years), there were 2 late deaths (8.3%), 6 patients (25%) presented significant left AV valve stenosis and 2 patients (8.3%) required valve replacement. Freedom from stenosis was 95 ± 4.9% at 1 year, 83.1 ± 8.9% at 3 years, 64.7 ± 13.5% at 5 years and 51.7 ± 15.8% at 10 years. Complete cleft closure was not associated with a significantly different freedom from left AV valve reoperation (log-rank test, P = 0.89) or significant stenosis (P = 0.47). CONCLUSION: Biventricular repair in parachute left AV valve and CAVC is feasible with acceptable mortality and freedom from stenosis. The burden of reoperation remains significant in this patient group.

Anomalous Aortic Origin of Coronary Arteries: A Single-Center Experience.

The aim of this article is to determine the clinical course and outcomes in subjects with anomalous aortic origin of coronary arteries (AAOCA), particularly after surgical repair. A single-center, retrospective review of patients with AAOCA with right or left interarterial or IM (IA or IM) or intraconal course from 1996-2014. Among 155 patients, median age at diagnosis was 8.5 (range: 0.1-50) years, and 65% were male. The AAOCA course was IA or IM in 151 (97%) and intraconal in 4 (3%). Anomalous right coronary artery (CA) was present in 127 (82%), of whom 52 (42%) had repair. Anomalous left CA (ALCA) was present in 28 (18%), of whom 20 (71%) had repair. In the surgical group, 70 (97%) had IA or IM CAs; CA unroofing was performed in 62 (86%). In univariable analysis, surgical management was associated with ALCA (28% vs 10%, P = 0.003), age > 10 years (median 11 vs 6 years, P < 0.001), symptoms (63% vs 13%, P < 0.001), and exercise restriction at the time of diagnosis (47% vs 13%, P < 0.001). In multivariable modeling, surgery was associated with chest pain or syncope (P < 0.001) and older age (P = 0.03). Major perioperative complications occurred in 4 cases (6%) and 1 patient had late aortic valve repair. In the surgical group, no patients died; in the observed group, 2 patients with anomalous right CA (2.3%) died of severe noncardiac comorbidities. In our center, surgery for AAOCA was not associated with mortality, and surgery was recommended in patients with ALCA with IA or IM course. Rare but serious surgical complications highlight the importance of long-term follow up of patients with AAOCA to develop evidence-based management guidelines.

Neonatal Mitral Valve Repair in Biventricular Repair, Single Ventricle Palliation, and Secondary Left Ventricular Recruitment: Indications, Techniques, and Mid-Term Outcomes.

OBJECTIVES: Although mitral valve repair is rarely required in neonates, this population is considered to be at high risk for adverse outcomes. The aim of this study was to review the indications for surgery, mechanisms, repair techniques, and mid-term outcomes of neonatal mitral valve repair. METHODS: The demographic, procedural, and outcome data were obtained for all neonates who underwent mitral valve repair from 2005 to 2012. The primary endpoints included mortality, transplantation, and mitral valve reoperation. RESULTS: Twenty patients were included during the study period. Median age at operation was 11 days (range: 3-25). Eleven patients (55%) presented with mitral stenosis, three had regurgitation (15%), and six had mixed mitral disease (30%). Nineteen of 20 patients had mild or less regurgitation on immediate postoperative imaging. During a median follow-up of 5 months (1 month-4.8 years), six patients died at a median of 33 months (7-41 months) from repair and one patient required orthotopic heart transplantation. Six patients required mitral valve reoperation, five for mitral valve re-repair, and one for mitral valve replacement. Freedom from death, transplantation, or mitral valve replacement was 84.2 ± 8.4% at 1 month, 71.3 ± 11% at 6 months, 64.1 ± 12% at 1 year, and 51.3 ± 15% at 2 years and was worse for patients presenting with mitral regurgitation compared to stenosis or mixed mitral valve disease. CONCLUSION: Although mitral valve repair can be performed with acceptable immediate postoperative result, this procedure carries a high burden of late death and mitral valve reoperations.

The safety and efficacy of antifibrinolytic therapy in neonatal cardiac surgery.

BACKGROUND: Neonates undergoing open-heart surgery are particularly at risk of postoperative bleeding requiring blood transfusion. Aprotinin has attained high efficacy in reducing the requirement for a blood transfusion following a cardiopulmonary bypass, but is seldom studied in the neonatal age group. The aim of this study was to compare the efficacy and adverse effects of aprotinin and tranexamic acid in neonates undergoing open-heart surgery at a single centre. METHODS: Between October 2003 and March 2008, perioperative data of 552 consecutive neonatal patients undergoing open-heart surgery in Children's Hospital Boston were reviewed. Among them, 177 did not receive antifibrinolytic therapy (Group A); 100 were treated with tranexamic acid only (Group B); and 275 patients received aprotinin with or without tranexamic acid (Group C). Except for antifibrinolytic therapy, the anaesthesiological and surgical protocols remained identical. Postoperative complications and in-hospital mortality were the primary study endpoints. RESULTS: Body weight and Risk Adjustment for Congenital Heart Surgery (RACHS-1) scores were statistically comparable among the three groups. No statistically significant differences were observed between the duration of hospitalization, chest tube drainage, reexploration for bleeding, and kidney function impairment. In Group C, less blood was transfused within 24 hours than in GroupB. Operative mortality was similar among the three groups. CONCLUSION: No further risk and kidney injury were observed in the use of aprotinin in neonatal cardiac surgery, aprotinin demonstrated a reduced requirement for blood transfusion compared with tranexamic acid. Our data provide reasonable evidence that aprotinin and tranexamic acid are safe and efficacious as antifibrinolytic modalities in neonatal patients undergoing cardiac surgery.

Evaluation of cerebral oxygenation and perfusion with conversion from an arterial-to-systemic shunt circulation to the bidirectional Glenn circulation in patients with univentricular cardiac abnormalities.

OBJECTIVE: Superior vena cava pressure after the bidirectional Glenn operation usually is higher than that associated with the preceding shunt-dependent circulation. The aim of the present study was to determine whether the acute elevation in central venous pressure was associated with changes in cerebral oxygenation and perfusion. DESIGN: Single-center prospective, observational cohort study. SETTING: Academic children's hospital. PARTICIPANTS: Infants with single-ventricle lesions and surgically placed systemic-to-pulmonary artery shunts undergoing the bidirectional Glenn operation. INTERVENTIONS: Near-infrared spectroscopy and transcranial Doppler sonography were used to measure regional cerebral oxygen saturation and cerebral blood flow velocity. MEASUREMENTS AND MAIN RESULTS: Mean differences in regional cerebral oxygen saturation and cerebral blood flow velocity before anesthetic induction and shortly before hospital discharge were compared using the F-test in repeated measures analysis of variance. In the 24 infants studied, mean cerebral oxygen saturation increased from 49%±2% to 57%±2% (p = 0.007), mean cerebral blood flow velocity decreased from 57±4 cm/s to 47±4 cm/s (p = 0.026), and peak systolic cerebral blood flow velocity decreased from 111±6 cm/s to 99±6 cm/s (p = 0.046) after the bidirectional Glenn operation. Mean central venous pressure was 8±2 mmHg postinduction of anesthesia and 14±4 mmHg on the first postoperative day and was not associated with a change in cerebral perfusion pressure (p = 0.35). CONCLUSIONS: The bidirectional Glenn operation in infants with a shunt-dependent circulation is associated with an improvement in cerebral oxygenation, and the lower cerebral blood flow velocity is likely a response of intact cerebral autoregulation.