Safety and utility of modified ultrafiltration in pediatric cardiac surgery.

INTRODUCTION: Modified ultrafiltration (MUF) is employed at the termination of cardiopulmonary bypass (CPB) in pediatric and neonatal patients undergoing congenital heart surgery to reduce the accumulation of total body water thus increasing the concentration of red blood cells and the other formed elements in the circulation. Modified ultrafiltration has been reported to remove circulating pro-inflammatory mediators that result in systemic inflammatory response syndrome (SIRS) postoperatively. METHODS: Four hundred patients undergoing cardiac surgery requiring cardiopulmonary bypass and weighing less than or equal to 12 kg were retrospectively evaluated for the effectiveness of MUF. After the termination of CPB, blood was withdrawn through the aortic cannula and passed through a hemoconcentrator attached to the blood cardioplegia set and returned to the patient through the venous cannula. The entire CPB circuit volume in addition to the patient's circulating blood volume were concentrated until the hematocrit value displayed on the CDI cuvette within the MUF circuit reached 45% or there was no more volume to safely remove. At the same time a full unit of FFP can be infused as water is being removed, thus maintaining euvolemia. RESULTS: MUF was performed in all 400 patients with no MUF-related complications. Following the conclusion of MUF, anecdotal observations included improved surgical hemostasis, improved hemodynamic parameters, decreased transfusion requirements, and decreased ventilator times. CONCLUSIONS: Complete MUF enables the clinician to safely raise the post-CPB hematocrit to at least 40% while potentially removing mediators that could result in SIRS. In addition a full unit of FFP can be administered while maintaining euvolemia.

Evaluation of centrifugal blood pumps in term of hemodynamic performance using simulated neonatal and pediatric ECMO circuits.

The objective of this translational study was to evaluate the FDA-approved PediMag, CentriMag, and RotaFlow centrifugal blood pumps in terms of hemodynamic performance using simulated neonatal and pediatric extracorporeal membrane oxygenation (ECMO) circuits with different sizes of arterial and venous cannulae. Cost of disposable pump heads was another important variable for this particular study. The experimental circuit was composed of one of the centrifugal pump heads, a polymethylpentene membrane oxygenator, neonatal and pediatric arterial/venous cannulae, and 1/4-inch ID tubing. Circuits were primed with lactated Ringer's solution and packed human red blood cells (hematocrit 35%). Trials were conducted at 36°C using the three pump heads and different cannulae (arterial/venous cannulae: 8 Fr/18 Fr, 10 Fr/20 Fr, and 12 Fr/22 Fr) at various flow rates (200-2400 mL/min, 200 mL/min increments) and rotational speeds. Pseudo patient pressure was 60 mm Hg. Real-time pressure and flow data were recorded for analysis. The RotaFlow pump had a higher pressure head and flow range compared with the PediMag and CentriMag pumps at the same rotational speed and identical experimental settings (P < 0.001). The PediMag pump had lower flow output than others (P < 0.001). Small-caliber arterial cannulae and higher flow rates predictably created higher circuit pressures and pressure drops. There was no significant difference in hemodynamic energy delivered to the pseudo patient with each of the three pumps. The arterial cannula had the highest pressure drop and hemodynamic energy loss in the circuit when compared to the oxygenator and arterial tubing. The RotaFlow centrifugal pump had a significantly better hemodynamic performance when compared to the PediMag and CentriMag blood pumps at identical experimental conditions in simulated neonatal and pediatric ECMO settings. In addition, the cost of the RotaFlow pump head ($400) is 20 to 30-fold less than the other centrifugal pumps [CentriMag ($12 000) or PediMag ($8000)] that were evaluated in this translational study.

Clinical outcomes of neonatal and pediatric extracorporeal life support: A seventeen-year, single institution experience.

The objective of this study was to describe a single-center experience with neonatal and pediatric extracorporeal life support (ECLS) and compare patient-related outcomes with those of the Extracorporeal Life Support Organization (ELSO) Registry. A retrospective review of subject characteristics, outcomes, and complications of patients who received the ECLS at Penn State Health Children's Hospital (PSHCH) from 2000 to 2016 was performed. Fisher's exact test was used to compare the PSHCH outcomes and complications to the ELSO Registry report. Data from 118 patients were included. Survival to discontinuation of the ECLS was 70.3% and 65.2% to discharge/transfer. Following circuitry equipment changes, the survival to discharge/transfer improved for both neonatal (<29 days) and pediatric (29 days to <18 years) patients. The most common complications associated with ECLS were clinical seizures, intracranial hemorrhage, and culture-proven infection. ECLS for pulmonary support appeared to be associated with a higher risk of circuit thrombus and cannula problems. When compared to the ELSO Registry, low volume ECLS centers, like our institution, can have outcomes that are no different or statistically better as noted with neonatal and pediatric cardiac patients. Pediatric patients requiring pulmonary support appeared to experience more mechanical complications during ECLS suggesting the need for ongoing technological improvement.

Evaluation of Combined Extracorporeal Life Support and Continuous Renal Replacement Therapy on Hemodynamic Performance and Gaseous Microemboli Handling Ability in a Simulated Neonatal ECLS System.

The objective of this study was to evaluate the hemodynamic performance and gaseous microemboli (GME) handling ability of a simulated neonatal extracorporeal life support (ECLS) circuit with an in-line continuous renal replacement therapy (CRRT) device. The circuit consisted of a Maquet RotaFlow centrifugal pump or HL20 roller pump, Quadrox-iD Pediatric diffusion membrane oxygenator, 8-Fr arterial cannula, 10-Fr venous cannula, and Better-Bladder (BB) with "Y" connector. A second Quadrox-I Adult oxygenator was added postarterial cannula for GME experiments. The circuit and pseudo-patient were primed with lactated Ringer's solution and packed human red blood cells (hematocrit 40%). All hemodynamic trials were conducted at ECLS flow rates ranging from 200 to 600 mL/min and CRRT flow rate of 75 mL/min at 36°C. Real-time pressure and flow data were recorded with a data acquisition system and GME were detected and characterized using the Emboli Detection and Classification Quantifier System. CRRT was added at distinct locations such that blood entered CRRT between the pump and oxygenator (A), recirculated through the pump (B), or bypassed the pump (C). With the centrifugal pump, all CRRT positions had similar flow rates, mean arterial pressure (MAP), and total hemodynamic energy (THE) loss. With the roller pump, C demonstrated increased flow rates (293.2-686.4 mL/min) and increased MAP (59.4-75.5 mm Hg) (P < 0.01); B had decreased flow rates (129.7-529.7 mL/min), and MAP (34.2-45.0 mm Hg) (P < 0.01); A maintained the same when compared to without CRRT. At 600 mL/min C lost more THE (81.4%) (P < 0.01) with a larger pressure drop across the oxygenator (95.6 mm Hg) (P < 0.01) than without CRRT (78.3%; 49.1 mm Hg) (P < 0.01). C also demonstrated a poorer GME handling ability using the roller pump, with 87.1% volume and 17.8% count reduction across the circuit, compared to A and B with 99.9% volume and 65.8-72.3% count reduction. These findings suggest that, in contrast to A and B, adding CRRT at position C is unsafe and not advised for clinical use.

Evaluation of Hemodynamic Performance of a Combined ECLS and CRRT Circuit in Seven Positions With a Simulated Neonatal Patient.

As it is common for patients treated with extracorporeal life support (ECLS) to subsequently require continuous renal replacement therapy (CRRT), and neonatal patients encounter limitations due to lack of access points, inclusion of CRRT in the ECLS circuit could provide advanced treatment for this population. The objective of this study was to evaluate an alternative neonatal ECLS circuit containing either a Maquet RotaFlow centrifugal pump or Maquet HL20 roller pump with one of seven configurations of CRRT using the Prismaflex 2000 System. All ECLS circuit setups included a Quadrox-iD Pediatric diffusion membrane oxygenator, a Better Bladder, an 8-Fr arterial cannula, a 10-Fr venous cannula, and 6 feet of »-inch diameter arterial and venous tubing. The circuit was primed with lactated Ringer's solution and packed human red blood cells resulting in a total priming volume of 700 mL for both the circuit and the 3-kg pseudopatient. Hemodynamic data were recorded for ECLS flow rates of 200, 400, and 600 mL/min and a CRRT flow rate of 50 mL/min. When a centrifugal pump is used, the hemodynamic performance of any combined ECLS and CRRT circuit was not significantly different than that of the circuit without CRRT, thus any configuration could potentially be used. However, introduction of CRRT to a circuit containing a roller pump does affect performance properties for some CRRT positions. The circuits with CRRT positions B and G demonstrated decreased total hemodynamic energy (THE) levels at the post-arterial cannula site, while positions D and E demonstrated increased post-arterial cannula THE levels compared to the circuit without CRRT. CRRT positions A, C, and F did not have significant changes with respect to pre-arterial cannula flow and THE levels, compared to the circuit without CRRT. Considering hemodynamic performance, for neonatal combined extracorporeal membrane oxygenation (ECMO) and CRRT circuits with both blood pumps, we recommend the use of CRRT position A due to its hemodynamic similarities to the ECMO circuit without CRRT.

An adolescent with chest pain and cardiac hemangioma.

Less than 5% of chest pain in children is cardiac in origin, yet this complaint still represents one of the top reasons children are referred to pediatric cardiologists. This article describes a patient whose cardiac tumor illustrates the challenges of evaluating pediatric chest pain and the Standardized Clinical Assessment and Management Plan algorithm that can help.

Apolipoprotein E levels in pediatric patients undergoing cardiopulmonary bypass.

Apolipoprotein E (apoE) may play a critical role in modulating the response to neurological injury after cardiopulmonary bypass (CPB) in children. Plasma samples were collected from 38 pediatric patients. Half of the patients received nonpulsatile flow and the other half underwent pulsatile flow during CPB. Plasma samples were collected at three time points: at baseline prior to incision (T1), 1 h after CPB (T2), and 24 h after CPB (T3). The study included 38 pediatric patients undergoing heart surgery (mean age 2.5 ± 2.1 years). Baseline apoE levels were low (<30 µg/mL) in 21 patients (55%). ApoE levels were significantly decreased at 1 h after CPB compared with baseline (22 ± 14 vs. 34 ± 18 µg/mL, P = 0.001). At 24 h after CPB, apoE levels were significantly increased compared with baseline (47 ± 25 vs. 34 ± 18 µg/mL, P = 0.002). Pulsatile mode was associated with lower apoE levels at 24 h after CPB compared with nonpulsatile mode (38 ± 14 vs. 57 ± 29 µg/mL, P = 0.018). ApoE levels correlated negatively with pump time (r = -0.525, P = 0.021) and cross-clamp time (r = -0.464, P = 0.045) at 24 h following CPB for the nonpulsatile group but not for the pulsatile group. In this cohort of young children with congenital heart disease, baseline apoE levels were low in the majority of patients prior to surgery. ApoE levels decreased further at 1 h after CPB, and then significantly increased by 24 h. The mode of perfusion and the duration of pump time and clamp time influence the apoE levels after CPB. An improved understanding of these mechanisms may translate into the development of new techniques to improve the clinical outcomes after pediatric CPB.

Comparative effects of pulsatile and nonpulsatile flow on plasma fibrinolytic balance in pediatric patients undergoing cardiopulmonary bypass.

In the brain, the components of the fibrinolytic system, tissue plasminogen activator (tPA) and its endogenous inhibitor plasminogen activator inhibitor-1 (PAI-1), regulate various neurophysiological and pathological responses. Fibrinolytic balance depends on PAI-1 and tPA concentrations. The objective of this study is to compare the effects of pulsatile and nonpulsatile perfusion on fibrinolytic balance in children undergoing pediatric cardiopulmonary bypass (CPB). Plasma PAI-1 antigen and tPA antigen were measured in 40 children (n = 20 pulsatile and n = 20 nonpulsatile group). Plasma samples (1.5 mL) were collected (i) prior to incision, (ii) 1 h after CPB, and (iii) 24 h after CPB. PAI-1 and tPA levels were measured at each time point. PAI-1 and tPA levels were significantly increased at 1 h after CPB, followed by a decrease at 24 h. Nonpulsatile but not pulsatile CPB lowered PAI-1 : tPA ratio significantly at 24 h (median PAI-1 : tPA ratio 4.63 ± 0.83:1.98 ± 0.48, P = 0.03, for the nonpulsatile group and 4.50 ± 0.92:3.56 ± 1.28, P = 0.2, for the pulsatile group). These results suggest that pulsatile flow maintains endogenous fibrinolytic balance after pediatric cardiopulmonary bypass. Further studies are needed to define the clinical significance of these differences.

Occult coronary ostial obstruction late after arterial switch operation.

Occult coronary artery obstruction can be a late source of morbidity and mortality following the arterial switch operation for transposition of the great arteries. We describe a case of undiagnosed left coronary ostial obstruction in a teenager which may have contributed to perioperative ventricular dysfunction and subsequent mortality following a reoperation many years after arterial switch.

The effects of pulsatile versus nonpulsatile flow on cerebral pulsatility index, mean flow velocity at the middle cerebral artery, regional cerebral oxygen saturation, cerebral gaseous microemboli counts, and short-term clinical outcomes in patients undergoing congenital heart surgery.

Objective: The objective of this retrospective review was to evaluate whether or not pulsatile flow improves cerebral hemodynamics and clinical outcomes in pediatric congenital cardiac surgery patients. Methods: This retrospective study included 284 pediatric patients undergoing congenital cardiac surgery with cardiopulmonary bypass support utilizing nonpulsatile (n = 152) or pulsatile (n = 132) flow. Intraoperative cerebral gaseous microemboli counts, pulsatility index, and mean blood flow velocity at the right middle cerebral artery were assessed using transcranial Doppler ultrasound. Clinical outcomes were compared between groups. Results: Patient demographics and cardiopulmonary bypass characteristics between groups were similar. Although the pulsatility index during aortic crossclamping was consistently higher in the pulsatile group (P < .05), a significant degree of pulsatility was also observed in the nonpulsatile group. No significant differences in mean cerebral blood flow velocity, regional cerebral oxygen saturation, or gaseous microemboli counts were observed between the perfusion modality groups. Clinical outcomes, including intubation duration, intensive care unit and hospital length of stay, and mortality within 180 days were similar between groups. Conclusions: Although the pulsatility index was greater in the pulsatile group, other measures of intraoperative cerebral perfusion and short-term outcomes were similar to the nonpulsatile group. These findings suggest that while pulsatile perfusion represents a safe modality for cardiopulmonary bypass support, its use may not translate into detectably superior clinical outcomes.

Use of aortic wall patches as leaflet replacement material during aortic valve repair.

Objectives: Aortic valve repair can be limited by inadequate leaflet tissue for proper coaptation. Various kinds of pericardium have been used for cusp augmentation, but most have failed because of tissue degeneration. A more durable leaflet substitute is needed. Methods: In this report, 8 consecutive cases are presented in which autologous ascending aortic tissue was used to augment inadequate native cusps during aortic valve repair. Biologically, aortic wall is a living autologous tissue that could have exceptional durability as a leaflet substitute. Techniques for insertion are described in detail, along with procedural videos. Results: Early surgical outcomes were excellent, with no operative mortalities or complications, and all valves were competent with low valve gradients. Patient follow-up and echocardiograms to a maximum of 8 months' postrepair remain excellent. Conclusions: Because of superior biologic characteristics, aortic wall has the potential to provide a better leaflet substitute during aortic valve repair and to expand patient categories amenable to autologous reconstruction. More experience and follow-up should be generated.

The kinetics of cardiopulmonary bypass: a dual-platform proteomics study of plasma biomarkers in pediatric patients undergoing cardiopulmonary bypass.

This study was designed to investigate the expression kinetics and patterns of plasma biomarkers throughout the pediatric cardiopulmonary bypass (CPB) procedure to help predict those patients most at risk for complications. This study sampled plasma from pediatric CPB patients at five time points before, during, and after CPB. A dual-platform proteomics approach was then utilized which incorporated two-dimensional difference gel electrophoresis (2D-DIGE) coupled with matrix-assisted laser desorption ionization-time-of-flight/time-of-flight tandem mass spectrometry, and multi-analyte profile (MAP) assays to identify changes in expression of plasma protein biomarkers and characterize the patterns of these changes. A combined total of 134 proteins were identified with significant changes between the two platforms, with 53 coming from 2D-DIGE, 90 from MAP, and nine proteins that were identified using both methods. The proteins were then divided into 12 major groups based on the expression patterns, and two of the most clinically relevant proteins having the greatest changes in expression were selected from each group to use as "predictor biomarkers." A potential model for prediction of patient outcome was then generated using these 24 proteins. The patterns of biomarker expression during pediatric CPB may provide insight into the prediction, prevention, or treatment of complications resulting from CPB, thereby helping to improve the outcomes of pediatric CPB patients and reduce the incidence of complications.

Exercise stress echocardiography after childhood Ross surgery: functional outcome in 26 patients from a single institution.

Adult studies suggest a better functional outcome after aortic valve replacement with a pulmonary autograft compared with mechanical or homograft valves. Little is known about functional results after Ross surgery in growing children. This study reports formal exercise stress echocardiographic data from 26 pediatric Ross patients. A retrospective cohort study analyzed stress echocardiographic data of patients who underwent Ross surgery as a child (<17 years old). All patients were operated by a single surgeon and underwent a Bruce protocol stress echocardiogram on the treadmill. Twenty-six patients (4 girls) were 9.3 ± 5.0 years at surgery and 14.9 ± 3.5 years (range 6.6-19.7 years) at follow-up. Mean follow-up was 5.4 ± 3.7 years (median 4.2). All were asymptomatic. The exercise time was normal in 87% of cases at 12.8 ± 2.5 min. On stress echocardiography, the mean right-ventricular outflow tract (RVOT) gradient increased from 38 ± 22 mmHg at rest to 82 ± 33 mmHg after exercise, but this did not correlate with exercise times. Stress echocardiography is useful in evaluating patients after childhood Ross surgery for aortic valve disease. In this pediatric cohort, most patients achieved normal exercise capacity. The presence of mild or moderate RVOT obstruction had no significant impact on exercise capacity.

Pacemaker Lead Placement via Transmural Approach in an Adult With Palliated Single Ventricle Heart Disease.

Given the lack of systemic venous return to the heart, palliated single ventricle patients frequently require epicardial pacemaker implantation for management of dysrhythmias including sinus node dysfunction, atrial arrhythmias, and heart block. Repeated device hardware replacement, frequently required due to high lead thresholds or other device failure, is a challenging and significant problem for this population. 3-dimensional imaging can assist in delineating the cardiac anatomy allowing for novel approaches to intervention. We review a patient with extracardiac Fontan circulation who underwent placement of an endocardial atrial pacemaker lead via a transmural approach with a 3D-printed model used for procedural guidance.

A Randomized Clinical Trial of Perfusion Modalities in Pediatric Congenital Heart Surgery Patients.

BACKGROUND: The objective of this randomized clinical trial was to investigate the effects of perfusion modalities on cerebral hemodynamics, vital organ injury, quantified by the Pediatric Logistic Organ Dysfunction-2 (PELOD-2) Score, and clinical outcomes in risk-stratified congenital cardiac surgery patients. METHODS: This randomized clinical trial included 159 consecutive congenital cardiac surgery patients in whom pulsatile (n = 83) or nonpulsatile (n = 76) perfusion was used. Cerebral hemodynamics were assessed using transcranial Doppler ultrasound. Multiple organ injury was quantified using the PELOD-2 score at 24, 48, and 72 hours. Clinical outcomes, including intubation time, intensive care unit length of stay (LOS), hospital LOS, and mortality, were also evaluated. RESULTS: The Pulsatility Index at the middle cerebral artery and in the arterial line during aortic cross-clamping was consistently better maintained in the pulsatile group. Demographics and cardiopulmonary bypass characteristics were similar between the 2 groups. While risk stratification with The Society of Thoracic Surgeons-European Association for Cardio-Thoracic Surgery (STAT) Mortality Categories was similar between the groups, Mortality Categories 1 to 3 demonstrated more patients than Mortality Categories 4 and 5. There were no differences in clinical outcomes between the groups. The PELOD-2 scores showed a progressive improvement from 24 hours to 72 hours, but the results were not statistically different between the groups. CONCLUSIONS: The Pulsatillity Index for the pulsatile group demonstrated a more physiologic pattern compared with the nonpulsatile group. While pulsatile perfusion did not increase plasma-free hemoglobin levels or microemboli delivery, it also did not demonstrate any improvements in clinical outcomes or PELOD-2 scores, suggesting that while pulsatile perfusion is a safe method, it not a "magic bullet" for congenital cardiac operations.

Improved cerebral oxygen saturation and blood flow pulsatility with pulsatile perfusion during pediatric cardiopulmonary bypass.

Brain monitoring techniques near-infrared spectroscopy (NIRS) and transcranial Doppler (TCD) ultrasound were used in pediatric patients undergoing cardiopulmonary bypass for congenital heart defect (CHD) repair to analyze the effect of pulsatile or nonpulsatile flow on brain protection. Regional cerebral oxygen saturation (rSO2) and cerebrovascular pulsatility index (PI) were measured by NIRS and TCD, respectively, in 111 pediatric patients undergoing bypass for CHD repair randomized to pulsatile (n = 77) or nonpulsatile (n = 34) perfusion. No significant differences in demographic and intraoperative data, including surgical risk stratification, existed between groups. Patients undergoing pulsatile perfusion had numerically lower decreases in rSO2 from baseline for all time points analyzed compared with the nonpulsatile group, with significant ∼12% lower decreases at 40 and 60 min after crossclamp. Patients undergoing pulsatile perfusion had numerically lower decreases in PI from baseline for the majority of time points compared with the nonpulsatile group, with significant ∼30% lower decreases between 5 and 40 min after crossclamp. Pulsatile flow has advantages over nonpulsatile flow as measured by NIRS and TCD, especially at advanced time points, which may improve postoperative neurodevelopmental outcomes.

Hemodynamic evaluation of the Avalon Elite bi-caval dual lumen cannulae.

In previous studies, we have evaluated the hemodynamic properties of selected oxygenators, pumps (centrifugal and roller), and single lumen cannulae. Because the dual lumen cannulae are widely used in veno-venous extracorporeal life support (ECLS) and are receiving popularity due to their advantages over the single lumen cannulae, we evaluated the flow ranges and pressure drops of three different sizes of Avalon Elite dual lumen cannulae (13Fr, 16Fr, and 19Fr) in a simulated neonatal ECLS circuit primed with human blood. The experimental ECLS circuit was composed of a RotaFlow centrifugal pump, a Capiox BabyRX05 oxygenator, 3 ft of 1/4-in venous and arterial line tubing, an Avalon Elite dual lumen cannula, and a soft reservoir as a pseudo-right atrium. All experiments were conducted at 37°C using an HCU 30 heater-cooling unit and with human blood at a hematocrit of 36%. The blood pressure in the pseudo-right atrium was continuously monitored and maintained at 4-5 mm Hg. For each cannula, pump flow rates and pressures at both the arterial and venous sides were recorded at revolutions per minute (RPMs) from 1750 to 3750 in 250 intervals. For each RPM, six data sets were recorded for a total of 162 data sets. The total volume of the system was 300 mL. The flow range for the 13Fr, 16Fr, and 19Fr cannulae were from 228 to 762 mL/min, 478 to 1254 mL/min, and 635 to 1754 mL/min, respectively. The pressure drops at the arterial side were higher than the venous side at all tested conditions except at 1750 rpm for the 19Fr cannula. The results of this study showed the flow ranges and the pressure drops of three different sized dual lumen cannulae using human blood, which is more applicable in clinical settings compared with evaluations using water.