Hemodynamic Changes with Umbilical Cord Milking in Nonvigorous Newborns: A Randomized Cluster Cross-over Trial.

OBJECTIVE: To assess the hemodynamic safety and efficacy of umbilical cord milking (UCM) compared with early cord clamping (ECC) in nonvigorous newborn infants enrolled in a large multicenter randomized cluster-crossover trial. STUDY DESIGN: Two hundred twenty-seven nonvigorous term or near-term infants who were enrolled in the parent UCM vs ECC trial consented for this substudy. An echocardiogram was performed at 12 ± 6 hours of age by ultrasound technicians blinded to randomization. The primary outcome was left ventricular output (LVO). Prespecified secondary outcomes included measured superior vena cava (SVC) flow, right ventricular output (RVO), peak systolic strain, and peak systolic velocity by tissue Doppler examination of the RV lateral wall and the interventricular septum. RESULTS: Nonvigorous infants receiving UCM had increased hemodynamic echocardiographic parameters as measured by higher LVO (225 ± 64 vs 187 ± 52 mL/kg/min; P < .001), RVO (284 ± 88 vs 222 ± 96 mL/kg/min; P < .001), and SVC flow (100 ± 36 vs 86 ± 40 mL/kg/min; P < .001) compared with the ECC group. Peak systolic strain was lower (-17 ± 3 vs -22 ± 3%; P < .001), but there was no difference in peak tissue Doppler flow (0.06 m/s [IQR, 0.05-0.07 m/s] vs 0.06 m/s [IQR, 0.05-0.08 m/s]). CONCLUSIONS: UCM increased cardiac output (as measured by LVO) compared with ECC in nonvigorous newborns. Overall increases in measures of cerebral and pulmonary blood flow (as measured by SVC and RVO flow, respectively) may explain improved outcomes associated with UCM (less cardiorespiratory support at birth and fewer cases of moderate-to-severe hypoxic ischemic encephalopathy) among nonvigorous newborn infants.

Ultrasound Imaging of the Superior Vena Cava: A State-of-the-Art Review.

Greater interest in imaging the superior vena cava (SVC) in recent years has arisen because of increased focus on disorders of the right heart; the growing use of transvenous access lines, dialysis catheters, and device leads; and the emergence of right ventricular mechanical circulatory support systems via the transcatheter approach. As a low-pressure venous conduit in the right upper mediastinum, the SVC is prone to compression by various pathologic processes, to invasion by malignancies originating in nearby structures, and to complications arising from intraluminal device leads and indwelling catheters. Computed tomography and magnetic resonance venography are the modalities of choice for structural imaging of the SVC. Ultrasound allows a reasonable, yet less detailed anatomic assessment of this venous conduit. Spectral and color Doppler imaging by ultrasound are the most valuable noninvasive tools for the interrogation of SVC blood flow, a marker of the filling pattern of the right heart. Analysis of the velocity, duration, and direction of the Doppler waveforms and their phasic response to respiration makes it possible to distinguish normal from abnormal flow patterns and offers diagnostic insights into disorders that affect right heart function. The aims of this review are to demonstrate the added value SVC imaging provides during transthoracic and transesophageal echocardiographic studies, to outline its usefulness for the detection and evaluation of structural abnormalities, and to detail the role of spectral Doppler imaging in aiding the diagnosis of various disorders that affect the right heart.

Intraventricular hemorrhage prediction in premature neonates in the era of hemodynamics monitoring: a prospective cohort study.

Unstable hemodynamics and prematurity are the main players in intraventricular hemorrhage (IVH) development. Our objective was to study 8 the use of superior vena cava flow (SVCF), left ventricular output (LVO), and right ventricular output (RVO), and anterior cerebral artery (ACA) Doppler measures in prediction of IVH in the first week of life in preterm infant ≤ 32 weeks and birth weight ≤ 1500 g. This prospective cohort study was conducted in 55NICU of Alexandria University maternity hospital. Of 147 enrolled patients, 132 infants born ≤ 32 weeks GA and birth weight ≤ 1500 g were eligible for- the study. One hundred twenty-seven infants completed the study. Infants were scanned for ACA-RI using transfontanellar ultrasound, and SVCF, LVO, and RVO using functional echocardiography in the first 24 h after birth. Patients had another two scans on DOL3 and 7 to detect IVH development. Low SVCF and high ACA-RI significantly increased the risk of IVH using logistic regression models with OR, 3.16; 95%CI, 1.19-8.39; P = 0.02 and OR, 1.64; 95%Cl, 1.10-2.44; P = 0.02, respectively. Low SVCF and high ACA-RI significantly increased risk of catastrophic IVH P = 0.025 and 0.023, respectively. Combined use of low SVCF < 55 ml/kg/min and ACA-RI > 0.75 is predictor of IVH with sensitivity 40.8% and 82.1% specificity. CONCLUSIONS: There are strong relations between both low SVCF and high ACA-RI, and IVH development in premature neonates ≤ 32 weeks and birth weight ≤ 1500 g, with more significance towards catastrophic IVH. Admission RSS and LVO are the strongest factors affecting SVCF. Maternal anemia, patent ductus arteriosus size (mm/kg), and capillary refill time were significantly associated with high ACA-RI. These findings help in more understanding of pathophysiological factors affecting central perfusion that might affect the longer term neurodeveopmental outcome. TRIAL REGISTRATION: This work was registered in clinical trial.gv no NCT05050032. WHAT IS KNOWN: •Whether SVCF and RI-ACA can predict IVH in preterm neonates is still debatable. WHAT IS NEW: •Low SVC flow and high ACA-RI significantly increased risk of IVH, confirming the role of hypoperfusion-reperfusion cycle in IVH development. The most striking result that combined metrics using the cut-off value of < 41 ml/kg/min for SVCF and > 0.85 for ACA-RI "in the first day of life" can correctly reject the presence of IVH in 98% of patients "during the first week of life."

An alternative explanation for the phasic variations in venous flow.

BACKGROUND: Phasic venous flow variation with respiration is surrounded by controversy and not well understood. The current concept assigns a major role to the "abdominal pump." According to this model, inspiratory increases in abdominal pressure compress the vena cava, increasing its internal venous pressure and propelling blood upstream. Some have assigned a secondary role to the "thoracic pump," with the negative intrapleural pressure aiding blood flow toward the heart. The aim of the present study was to examine the phasic changes in flow, pressure, and volume in the central veins and named tributaries. METHODS: Caliber area changes were measured using intravascular ultrasonography in 37 patients undergoing iliac vein stenting. The pressure was measured in 48 patients using transducer tip catheters with electronic zero calibration. Duplex ultrasound flow in the head and neck and truncal and limb veins during inspiration and expiration was measured in 15 normal volunteers. RESULTS: The caliber of the abdominal inferior vena cava had increased by 32% and its lateral pressure had decreased significantly during inspiration. Intravenous pressure in the central veins of the chest and right atrium was positive at 6 to 14 mm Hg. Negative pressures were rarely seen and then only transiently. The internal jugular vein displayed little phasic variation. The upper limb veins displayed weak inspiratory phasicity. Phase polarity was reversed in the lower limbs, with near flow stoppage during inspiration. CONCLUSIONS: These observations conflict with the current notions of venous flow phasicity, which are based on push-pull pressure changes in the abdominal and thoracic veins. The paradoxical inspiratory inferior vena cava caliber increase probably explains the concurrent pressure decrease. Sustained negative pressures in the thoracic central veins and right atrium did not occur. We have proposed an alternate hypothesis for venous flow phasicity based on alternate stretching and relaxation of the mobile section of the great veins with respiratory movement.

Cytokeratin-positive interstitial reticulum cell (CIRC) tumor in the lymph node: a case report of the transformation from the epithelioid cell type to the spindle cell type.

BACKGROUND: Cytokeratin-positive interstitial reticulum cells (CIRCs), which are a subgroup of fibroblastic reticular cells (FRCs), are known to be present in the lymph nodes. There have been only a few cases of tumors derived from CIRCs. CASE PRESENTATION: We have reported a new case involving a CIRC tumor in a 75-year-old man and reviewed the literature. The resected mediastinal lymph nodes showed epithelial-like proliferation of large atypical round and polygonal epithelioid cells. The tumor cells expressed CK8, CK18, CAM5.2, AE1/AE3, epithelial membrane antigen, vimentin, fascin, and some FRC markers, which is consistent with the diagnosis of a CIRC tumor. Following chemotherapy, the CIRC tumor was observed to have responded very well and became difficult to confirm on imaging, but a small cell lung carcinoma developed 12 months later. Chemoradiotherapy was performed, but the patient passed away 29 months after the initial diagnosis. The autopsy revealed the recurrence of the CIRC tumor, residual small cell lung carcinoma, and a very small latent carcinoma of the prostate. The relapsed CIRC tumor cells had a spindle shape; they were highly pleomorphic and had invaded the superior vena cava. CONCLUSION: We first reported autopsy findings of CIRC tumors and demonstrated the transformation of the tumor from the epithelioid cell type to the spindle cell type.

Relation of Right Atrial Volume, Systemic Venous Dimensions, and Flow Patterns to Right Atrial Pressure in Infants and Children.

Echocardiographic assessment of right atrial (RA) volume, inferior vena cava (IVC) diameter, and hepatic vein flow velocity independently correlate with the RA pressure by direct catheter measurement in adults. We prospectively collected invasive RA pressure measurements and echocardiographic data in infants and young children with the goal of developing a predictive model to noninvasively determine normal RA pressure. All subjects had a central venous catheter through which RA pressure could be transduced. Specific inclusion criteria consisted of (1) biventricular heart, (2) absence of inotropes, (3) sinus rhythm, and (4) at least 24 hours from surgery. Two-dimensional echocardiography (2DE)-Doppler and 3DE-Doppler were used to measure RA volume, systemic venous diameters, and flow velocity. Regression equations of RA pressure with RA volume, systemic venous size, and flow velocity were explored. Of 46 studies, 43 (93%) had echocardiograms adequate for analysis. RA pressure did not correlate with body surface area or age (p = 0.69, p = 0.87). The mean indexed RA volume by 3DE-Doppler was significantly higher than by 2DE (p <0.005). On multivariable analysis, only IVC systolic flow velocity and systolic 2D Simpson's derived indexed RA volume demonstrated significant independent correlation with RA pressure, resulting in the equation: RA pressure (mm Hg) = 7.35 - 0.0025 × IVC systolic flow velocity (cm/s) + 0.119 × indexed RA volume by systolic 2D Simpson's (ml/m2). RA pressure did not show correlation with systemic venous diameters or systolic and diastolic flow velocities in the SVC and hepatic veins. In conclusion, regression incorporating 2DE-derived RA volume and IVC systolic flow velocity provided the best noninvasive estimate of normal RA pressure in infants and children. The model derived requires validation in an independent sample.

A pulsatile hemodynamic evaluation of the commercially available bifurcated Y-graft Fontan modification and comparison with the lateral tunnel and extracardiac conduits.

OBJECTIVE: Fontan completion, resulting in a total cavopulmonary connection, is accomplished using a lateral tunnel, extracardiac conduit, or bifurcated Y-graft. The use of Y-grafts is hypothesized to provide symmetric hepatic blood flow distribution to the lungs, a factor related to pulmonary arteriovenous malformations. The present study evaluates the hemodynamic performance of the largest commercially available Y-graft cohort to date, highlights 6 representative cases, and compares commercially available Y-graft performance with lateral tunnel/extracardiac conduit connections. METHODS: A total of 30 patients with commercially available Y-grafts and 30 patients with lateral tunnel/extracardiac conduits were analyzed. Total cavopulmonary connection anatomies and flow waveforms were reconstructed using cardiac magnetic resonance images and phase-contrast cardiac magnetic resonance. Computational fluid dynamic simulations were performed to quantify total cavopulmonary connection power loss, resistance, and hepatic flow distribution. Comparisons between graft types were investigated. RESULTS: Total cavopulmonary connection resistance was significantly higher for Y-grafts. Hepatic flow distribution was similar overall but showed discrepancies at extreme values with more unbalanced flow in the Y-graft cohort. Power loss was more sensitive to left pulmonary artery stenosis in the Y-graft cohort. Prediction of Y-graft hepatic flow distribution is multifactorial. CONCLUSIONS: Commercially available Y-grafts do not inherently provide more balanced hepatic flow distribution than lateral tunnel/extracardiac conduit connections, which are more energetically favorable and less sensitive to pulmonary artery stenosis. Graft type should be considered on an individual basis because hemodynamic performance is based on a combination of factors, including pulmonary flow distribution, pulmonary artery stenosis, and superior vena cava positioning.

Effect of External Positive and Negative Pressure on Venous Flow in an Experimental Model.

OBJECTIVE: Positive external pressure is said to decrease transmural pressure; negative pressure in the pleural cavity is widely believed to result in negative pressure in systemic chest veins. The discrepancy between erect column height and foot venous pressure has been explained on this basis. METHODS: These core concepts rest on static closed models that may not be appropriate. This study examined the effects of external pressures in a dynamic open model that may better reflect in vivo conditions. Flow in a Penrose drain enclosed in a chamber that could be positively or negatively pressurized was used. Input and output reservoirs with pressures in the physiological range provided flow. Flow and pressure were monitored in horizontal and erect models with modifications to suit particular experiments. RESULTS: The discrepancy between foot venous pressure and erect venous column height was shown in this experimental model to be a result of two flows in opposite directions (superior and inferior vena cavae) meeting at the zero reference level at the heart; the upper column pressure therefore does not register at the foot. Positive external pressure results in slowing of velocity with conversion to pressure. Internal and transmural pressures therefore do not decrease. Negative external pressure has only a marginal effect on flow; importantly, internal pressure does not become negative. In an experimental set-up it was shown that negative pressure in chest veins was not necessary for air embolism to occur. CONCLUSION: Persistent negative pressure in systemic chest veins probably does not occur. The reason for the discrepant foot venous pressure is likely to be a result of dynamic flow and not negative pressure in chest veins. External positive pressure results in slowing of velocity but the transmural pressure remains largely unchanged.

Energetic implications of vessel growth and flow changes over time in Fontan patients.

BACKGROUND: As patients with a single-ventricle physiology age, long-term complications inherent to this population become more evident. Previous studies have focused on correlating anatomic and hemodynamic performance, but there is little information of how these variables change with time. Vessel growth and flow rate changes were quantified using cardiac magnetic resonance and their effects on hemodynamics were assessed, which could affect the long-term outcome. METHODS: Forty-eight patients with a lateral tunnel or extracardiac conduit Fontan who underwent two cardiac magnetic resonance scans (average interval, 5.1 ± 2.3 years) were studied. Total cavopulmonary connection anatomic and flow variables were reconstructed and normalized to body surface area(1/2). Total cavopulmonary connection hemodynamic efficiency (indexed power loss) was obtained through computational fluid dynamic modeling. RESULTS: Absolute vessel diameters increased with time, normalized diameters decreased, and vessel mean flow rates remained unchanged. Indexed power loss changed significantly in the cohort, as well as in patients in whom the minimum normalized left pulmonary artery decreased. Age at first scan and connection type (lateral tunnel or extracardiac conduit) were not associated with changes in indexed power loss. CONCLUSIONS: We present the largest serial cardiac magnetic resonance Fontan cohort to date. Although flow rates increased proportionally to body surface area, vessel diameters did not match somatic growth. As a result, energy losses increased significantly with time in the cohort analyzed.

Evolution of bubbles from gas micronuclei formed on the luminal aspect of ovine large blood vessels.

It has been shown that tiny gas nanobubbles form spontaneously on a smooth hydrophobic surface submerged in water. These nanobubbles were shown to be the source of gas micronuclei from which bubbles evolved during decompression of silicon wafers. We suggest that the hydrophobic inner surface of blood vessels may be a site of nanobubble production. Sections from the right and left atria, pulmonary artery and vein, aorta, and superior vena cava of sheep (n=6) were gently stretched on microscope slides and exposed to 1013 kPa for 18 h. Hydrophobicity was checked in the six blood vessels by advancing contact angle with a drop of saline of 71±19°, with a maximum of about 110±7° (mean±SD). Tiny bubbles ~30 µm in diameter rose vertically from the blood vessels and grew on the surface of the saline, where they were photographed. All of the blood vessels produced bubbles over a period of 80 min. The number of bubbles produced from a square cm was: in the aorta, 20.5; left atrium, 27.3; pulmonary artery, 17.9; pulmonary vein, 24.3; right atrium, 29.5; superior vena cava, 36.4. More than half of the bubbles were present for less than 2 min, but some remained on the saline-air interface for as long as 18 min. Nucleation was evident in both the venous (superior vena cava, pulmonary artery, right atrium) and arterial (aorta, pulmonary vein, left atrium) blood vessels. This newly suggested mechanism of nucleation may be the main mechanism underlying bubble formation on decompression.

Anatomical and functional assessment of the intra-atrial lateral tunnel in the Fontan circulation.

OBJECTIVES: In patients after completion of the total cavopulmonary connection (TCPC) with an intra-atrial lateral tunnel, deviations of the tunnel from an ideal straight tubular shape were observed. However, little is known about frequency and adverse effects of such shape deviations. We sought to analyse tunnel anatomy, dimensions and blood flow using cardiac magnetic resonance imaging (CMR). METHODS: Fifty-four patients with hypoplastic left heart syndrome (HLHS; mean age 6.0 ± 2.4 years) underwent CMR with gradient-echo cine sequences, 2D- and 3D-phase-contrast imaging. We analysed anatomy, diameters, cross-sectional areas, volumes and blood flow of the tunnel. RESULTS: Twenty-five patients had a tubular tunnel. In 29 patients, bulging and/or narrowing of the tunnel were present. Cross-sectional areas and volumes of the tunnel were not significantly different between the two groups. There were also no differences for the mean blood flow and the mean and maximal flow velocity (P = 0.05-0.6). In all the patients, the normalized tunnel volume was related to age (r = 0.44; P = 0.002) and body surface area (BSA; r = 0.42; P = 0.005). The mean tunnel blood flow correlated with age (r = 0.73; P = 0.001) and BSA (r = 0.83; P < 0.0001). CONCLUSIONS: A considerable percentage of patients with an intra-atrial lateral tunnel develop mild deviations of the tunnel from ideal tubular shape. The correlation between tunnel volume and mean blood flow with age and BSA suggests that the capacity of the tunnel adjusts to body growth, independent of tunnel shapes that deviate from a fluid-dynamically favourable shape. Follow-up CMRs are needed to detect long-term effects of irregular tunnel shapes on flow dynamics.

A modified Glenn shunt improves haemodynamics in acute right ventricular failure in an experimental model.

OBJECTIVES: Right heart failure is a major cause of morbidity and mortality after left ventricular assist device implantation and is still hard to predict. This study investigated the haemodynamic effect of a modified Glenn shunt on induced right ventricular (RV) failure. METHODS: Isolated RV failure was induced by coronary ligation in 11 pigs. A modified Glenn shunt was established by a superior vena cava to pulmonary artery connection. Haemodynamic data were obtained at baseline, RV failure, and RV failure and open shunt. Myocardial biopsies were taken to ascertain established heart failure. RESULTS: RV failure defined as right atrial pressure ≥20 mmHg was achieved in all 11 animals. A reduction in cardiac output (CO) from 3.7 (3.5-4.2) to 2.3 l/min (2.0-2.6) and mean arterial pressure (MAP) from median 72.7 (70.1-82.2) to 55.9 mmHg (52.6-59.8) was seen during heart failure. The median flow in the shunt was 681 ml. Right atrial pressures decreased from 20.3 (19.6-21.1) to 13.4 mmHg (12.7-14.0), and RV pressures decreased from 18.1 (16.4-20.1) to 13.6 mmHg (13.5-14.2) with open shunt (P = 0.001 for both). CO increased to 2.9 l/min (2.4-3.3) when the shunt was in use. Mixed venous oxygen saturation increased with the shunt from 32 (27-38) to 49% (45-56), P = 0.001. Genes associated with heart failure were upregulated during heart failure. CONCLUSIONS: A modified Glenn shunt improved haemodynamics by reduced right atrial pressure, increased CO, MAP and mixed venous oxygen saturation in an experimental model of induced RV failure.

Femoral venous oxygen saturation is no surrogate for central venous oxygen saturation.

OBJECTIVE: The purpose of our study was to determine if central venous oxygen saturation and femoral venous oxygen saturation can be used interchangeably during surgery and in critically ill patients. DESIGN: Prospective observational controlled study. SETTING: Nonacademic university-affiliated teaching hospital in The Netherlands. PATIENTS: One hundred cardiac outpatients, 30 high-risk surgical patients, and 30 critically ill patients. INTERVENTIONS: None. METHODS AND MAIN RESULTS: We concurrently determined femoral venous oxygen saturation and central venous oxygen saturation in a group of 100 stable cardiac patients, which served as control group. Furthermore, we determined simultaneously femoral venous oxygen saturation and central venous oxygen saturation in 30 surgical patients and in 30 critically ill patients and evaluated changes over time. Correlation and agreement of femoral venous oxygen saturation and central venous oxygen saturation were assessed, including the difference between femoral venous oxygen saturation and central venous oxygen saturation.Despite significant correlation between obtained values of femoral venous oxygen saturation and central venous oxygen saturation (rs = 0.55; p < .001), the limits of agreement were wide in the control group (mean bias 2.7% ± 7.9%; 95% limits of agreement -12.9% to 18.2%). In both the surgical and critically ill patients, limits of agreement (mean bias of -1.9% ± 9.3%; 95% limits of agreement -20.0% to 16.3%, and mean bias of 4.6% ± 14.3%; 95% limits of agreement -23.5% to 32.6%, respectively) were wide. Results for changes of femoral venous oxygen saturation and central venous oxygen saturation were similar. During initial treatment of critically ill patients, the difference between femoral venous oxygen saturation and central venous oxygen saturation including its range of variation diminished. CONCLUSION: There is lack of agreement between femoral venous oxygen saturation and central venous oxygen saturation in both stable and unstable medical conditions. Thus, femoral venous oxygen saturation should not be used as surrogate for central venous oxygen saturation.

[Evaluation of cerebral oxygenation changes with clamping of the left superior vena cava by near-infrared spectroscopy].

OBJECTIVE: The left superior vena cava (LSVC) is often complicated with congenital heart defect. Although we simply clamp LSVC during cardio-pulmonary bypass (CPB), appropriateness of this technique has not been clarified. We noninvasively evaluate cerebral tissue oxygenation while the clamping of LSVC under CPB by near-infrared spectroscopy (NIRS). METHODS: Six children (3 male and 3 female; aged 1.0 +/- 0.6 year) undergoing open heart surgery were studied. The NIRO 300 was incorporated into an established multimodal monitoring system. Tissue oxygenation index (TOI), oxyhemoglobin (O2Hb), and deoxyhemoglobin (HHb) changes were assessed and compared with LSVC pressure. RESULTS: There were no significant changes in cerebral oxygen delivery after LSVC clamp. LSVC pressure increased from 7.3 +/- 1.8 mmHg to 20.1 +/- 2.6 just after LSVC clamp, but gradually decreased without any maneuver. CONCLUSION: These data demonstrated that LSVC could be safely clamped when LSVC pressure was under 30 mmHg.

Long-term patency of the stapled bovine pericardial conduit for replacement of the superior vena cava.

OBJECTIVE: Artificial prosthesis of the superior vena cava (SVC) may occlude with time. For this reason, we proposed in 2003 the use of a biological material (bovine pericardium) and devised an original technique to construct the prosthetic conduit. We hereby report the long-term results in 15 patients. METHODS: The SVC prosthetic conduit is realized by wrapping a bovine pericardial leaflet around a 5 or 10 cm(3) syringe and stapling it on the side by a 60-80 linear stapler. This procedure is carried out intra-operatively after the size of the patient's SVC has been ascertained; the conduit is then cut to the appropriate length. We have employed this technique in 15 patients with lung (eight) or mediastinal (seven) tumors; after a minimum follow-up of 1 year, all patients underwent computed tomographic-volume rendering (CT-VR) studies of the SVC. RESULTS: Technically, the stapled pericardial conduit has several advantages: (1) it is simple and expeditious; (2) it allows an even and regular suture line, which cannot be achieved by hand suturing; (3)'one size fits all': with one single pericardial leaflet, conduits of all sizes can be realized; this is important for an operation which is performed only few times per year; (4) patency is granted by the intrinsic rigidity of the pericardium and staple line, without the need for any reinforcement; (5) different calibers at the two extremities can be obtained by simply placing the stapler obliquely; and (6) the staple line is excellent for the orientation of the conduit while suturing. In our patients, SVC clamping time ranged between 18 and 50 min (mean 29 min); one patient needed cardiopulmonary bypass. Intra-operative anticoagulation (1.500-2.500 units of heparin) was continued postoperatively subcutaneously for 7 days and then shifted to oral anticoagulation for 6 months. One patient died postoperatively of heart failure (mortality 6%). One to 5 years after surgery, CT-VR showed full patency of the pericardial conduit, no clots or thrombus formation, and absence of collateral venous circulation in all 14 patients. One- and 5-year survival was 93% and 73%, respectively (Kaplan-Meier). CONCLUSIONS: The stapled bovine pericardial conduit is a simple, expeditious, and economic solution to SVC replacement, and offers reliable long-term patency without permanent anticoagulation.

Cavopulmonary assist: (em)powering the univentricular fontan circulation.

Since the Fontan/Kreutzer procedure was introduced, evolutionary clinical advances via a staged surgical reconstructive approach have markedly improved outcomes for patients with functional single ventricle. However, significant challenges remain. Early stage mortality risk seems impenetrable. Serious morbidities - construed as immutable consequences of palliation - have hardly been addressed. Late functional status is increasingly linked to pathophysiologic consequences of prior staged procedures. As more single-ventricle patients survive into adulthood, Fontan failure is emerging as an intractable problem for which there is no targeted therapy. Incremental solutions to address these ongoing problems have not had a measurable impact. Therefore, a fundamental reconsideration of the overall approach is reasonable and warranted. The ability to provide a modest pressure boost (2 to 6 mmHg) to existing blood flow at the total cavopulmonary connection can effectively restore more stable biventricular status. This would impact not only treatment of late Fontan failure, but also facilitate early surgical repair. A realistic means to provide such a pressure boost has never been apparent. Recent advances are beginning to unravel the unique challenges that must be addressed to realize this goal, with promise to open single-ventricle palliation to new therapeutic vistas.

Accidental cross-clamping of the superior vena cava: management and BIS evolution.

The case of a 38-year old man with recurrent adenocarcinoma of the right lung and infiltration of the thoracic wall, who underwent a right pneumonectomy with thoracic wall resection, is described. Dissection of the right pulmonary hilous was extremely difficult due to the previous operations. The superior vena cava (SVC) was accidentally ligated, resulting in profound hypotension and increased venous pressure in the internal jugular vein. Immediate blood aspiration through a 8.5-French introducer sheath lowered the venous congestion. After the SVC was cross-clamped, the Bispectral Index (BIS) acutely decreased to 0 and remained low during the resuscitation. Over the next 5 hours, BIS was directly affected by mean arterial pressure. Four days postoperatively, the patient was neurologically intact.

Systemic arteriovenous fistulae for end-stage cyanosis after cavopulmonary connection: a useful bridge to transplantation.

OBJECTIVE: Intractable cyanosis after partial or complete cavopulmonary connection may rarely be managed by creating a systemic arteriovenous fistula. We investigated the long-term performance of arteriovenous fistulae. METHODS: All 21 patients who received an arteriovenous fistula at The Hospital for Sick Children since the 1950s were investigated using parametric competing risk techniques. Primary arteriovenous fistula indication was (1) suboptimal pulmonary blood flow (N = 15) or (2) pulmonary shunting via pulmonary arteriovenous malformations (N = 6). Arteriovenous fistula longevity was determined by time to "occlusion" (absence of arteriovenous fistula flow via surgical ligation or spontaneous occlusion). RESULTS: All 21 patients had previously undergone second-stage palliation (Glenn shunt = 13; bidirectional shunt = 9). Five patients had undergone Fontan completion. Death in the presence of a functioning arteriovenous fistula occurred in 5 patients. Patients with bidirectional shunts had a significantly higher risk of death with a functioning arteriovenous fistula in situ (P = .04). High hemoglobin concentrations were associated with best outcome, and levels less than 170 g/L were associated with a high risk of death despite a functioning arteriovenous fistula (P < .01). Arteriovenous fistula occlusion occurred in 10 patients. Earlier occlusion was associated with previous Fontan completion (P = .02) and pulmonary arteriovenous malformations (P = .03). Surgical ligation during cardiac transplantation was the cause of occlusion in 7 patients. In these 7 patients, the arteriovenous fistula functioned for a median of 4.8 years. After transplantation, survival was 67% + or - 19% at 5 years. Overall survival was 73% + or - 10% 15 years after receiving an arteriovenous fistula (longest survival, 27.3 years). CONCLUSION: In patients with adequate hematocrit, arteriovenous fistula offers an effective bridge to transplantation when a high-risk Fontan procedure is deferred. Performance is best after unidirectional cavopulmonary connection and worse in the presence of pulmonary arteriovenous malformations. Survival is 75% at 15 years, despite being considered end stage.

Optimal conduit size of the extracardiac Fontan operation based on energy loss and flow stagnation.

BACKGROUND: In the extracardiac Fontan operation, larger conduits are used when considering the patients' growth rate. However, larger conduits may cause inefficient flow due to turbulence or stagnation, resulting in late problems such as thrombosis or stenosis. Our objective was to reveal the physiologic effects of respiration and exercise using numerical models, based on the energy loss and flow stagnation, and to determine optimal conduit size. METHODS: For the Fontan operation, a conduit from 14 to 22 mm was created based on angiographic data from 17 Fontan patients (mean age, 36.0 months; mean body surface area, 0.53 m(2)). Respiratory-driven flow of the superior and inferior vena cava was determined at rest and during exercise on two levels (0.5 and 1.0 W/kg) by magnetic resonance imaging flow studies. Flow stagnation was defined as the volume of the region where flow velocity was less than 0.01 m/second at both the expiratory and inspiratory phases. RESULTS: In larger conduits, backward flow at the expiratory phase was prominent. Energy loss was small even during exercise, but the change was slightly larger between 14 and 16 mm than other conduit sizes (14 mm, 5.759 mW; 16 mm, 4.881 mW; and 22 mm, 4.199 mW during 1.0 W/kg exercise). Stagnation volume at the expiratory phase increased with an increase of conduit size (14 mm, 9.20% vs 22 mm, 33.9% conduit volume at rest). CONCLUSIONS: Fontan circulation is a low-energy system even during exercise. Larger conduits were proven to have redundant spaces, thus 16 and 18 mm conduits were optimal.

Near-infrared spectroscopy correlates with continuous superior vena cava oxygen saturation in pediatric cardiac surgery patients.

BACKGROUND: Cerebral regional oxygen saturation (rSO(2)) measured with near-infrared spectroscopy (NIRS) has a well-proven clinical utility. A goal-oriented treatment based on the rSO(2) resulted in a significant reduction in major morbidity and in a shortening of postoperative hospital stay in patients undergoing coronary revascularization. In this study, we have compared the values of superior vena cava saturation (ScvO(2)) continuously measured with a Pediasat catheter and the corresponding NIRS rSO(2) values obtained during cardiac operations in pediatric patients. METHODS: This was a prospective observational study enrolling fifteen pediatric patients (age: 6 days-7 years) undergoing cardiac operations. ScvO(2) data obtained with the Pediasat during the operation were compared with simultaneously recorded NIRS rSO(2) values. RESULTS: One hundred and seventeen matched sets of data were obtained during the operation. ScvO(2) continuously measured with the Pediasat was significantly correlated with the corresponding NIRS rSO(2) values. However, there was a constant positive bias (ScvO(2) values were higher than NIRS rSO(2) values) of 5.6%, with a precision of 10.4%. Time-related percentage changes of NIRS rSO(2) were significantly correlated with the corresponding ScvO(2) percentage changes. A decrease in ScvO(2) is predictive for a decrease in rSO(2) with a sensitivity of 73.7% and a specificity of 85.7%. CONCLUSIONS: The continuous measurement of ScvO(2) values obtained by the Pediasat may provide useful information about the metabolic conditions of the brain during cardiac operations in pediatric patients if considered as percentage changes. Absolute values of ScvO(2) tend to overestimate the correspondent rSO(2) values.