Cavopulmonary Circulation Research Articles

Combined Heart-Liver vs Isolated Heart Transplantation in Adults With Congenital Heart Disease

BackgroundDespite an increasing number of adults with congenital heart disease undergoing combined heart-liver transplantation (CHLT), there is a paucity of literature analyzing posttransplant outcomes. We analyzed the incidence and outcomes of congenital heart disease patients undergoing CHLT compared with those undergoing isolated heart transplantation (HT). MethodsThis was a retrospective analysis of all adult (≥18 years) congenital heart disease patients undergoing CHLT or HT between 2000 and 2020 in the Organ Procurement and Transplantation Network database. The primary outcome was death at 30 days and 1 year after transplantation. ResultsOf 1214 recipients included for analysis, 92 (8%) underwent CHLT and 1122 (92%) underwent HT. Patients undergoing CHLT and HT were similar in the distribution of age, sex, and serum bilirubin. Upon adjusted analysis with HT as the reference, undergoing CHLT was associated with a similar hazard of 30-day mortality between 2000 and 2017 (hazard ratio [HR], 0.51; 95% CI, 0.12-2.08; P = .35) and 2018 and 2020 (HR, 2.32; 95% CI, 0.88-6.13; P = .09). Similarly, there was no difference in the hazard of 1-year mortality for patients undergoing CHLT between 2000 and 2017 (HR, 0.60; 95% CI, 0.22-1.63; P = .32) and 2018 and 2020 (HR, 1.52; 95% CI, 0.66-3.53; P = .33) compared with HT. ConclusionsThe number of adults undergoing CHLT continues to rise. Given comparable survival outcomes between CHLT and HT, our findings demonstrate the former as a viable option for complex congenital heart disease patients with failing cavopulmonary circulation and associated liver disease. Future studies should delineate factors associated with early hepatic dysfunction to help identify congenital heart disease patients that would benefit from CHLT.

Mechanical support for the failing single ventricle after Fontan

Mechanical support for the failing single ventricle after Fontan

Abnormalities in the Von Willebrand-Angiopoietin Axis Contribute to Dysregulated Angiogenesis and Angiodysplasia in Children With a Glenn Circulation

Children with a bidirectional superior cavopulmonary (Glenn) circulation develop angiodysplasia and pulmonary arteriovenous malformations (AVMs). The von Willebrand factor (vWF)-angiopoietin axis plays a major role in AVM formation in multiple diseases. We observed derangements in global angiogenic signaling, vWF metabolism, angiopoietins, and invitro angiogenesis in children with a Glenn circulation versus controls and within Glenn pulmonary versus systemic circulations. These findings support the novel hypothesis that abnormalities in the vWF-angiopoietin axis may dysregulate angiogenesis and contribute to Glenn pulmonary AVMs. The vWF-angiopoietin axis may be a target to correct angiogenic imbalance in Glenn patients, for whom no targeted therapy exists.

Extensive Hilum to Hilum Pulmonary Artery Plasty in Stage II Palliation of Hypoplastic Left Heart Syndrome

It is crucial to have an adequate-size unobstructed branch pulmonary artery architecture to achieve an ideal cavopulmonary circulation. Branch pulmonary artery distortion, stenosis, or hypoplasia is a common problem following the stage I Norwood procedure for infants with hypoplastic left heart syndrome regardless of the shunt type. This technical review describes the surgical principle and techniques of the extensive hilum to hilum branch pulmonary artery reconstruction at the time of stage II palliation, bidirectional cavopulmonary shunt in infants with hypoplastic left heart syndrome.

STROKE AND CONGESTIVE HEART FAILURE IN A PATIENT WITH CONGENITAL DEXTROCARDIA AND SINGLE VENTRICLE AFTER FONTAN PROCEDURE

SESSION TITLE: Medical Student/Resident Cardiovascular Disease Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: October 18-21, 2020 INTRODUCTION: Fontan's procedure is the definitive palliative surgery for patients with single ventricle, creating permanent cavopulmonary circulation. CASE PRESENTATION: This is a 19-year-old male who was diagnosed with situs solitus with isolated dextrocardia, TGA, single ventricle with pulmonary and tricuspid atresia at birth. The patient had a series of cardiac corrective surgeries ending with permanent fenestrated Fontan’s total cavopulmonary connection. Post-operatively, he developed thromboembolic stroke, and was found to have an extensive thrombus within the left pulmonary artery with extension to Fontan's baffle. He was treated with Warfarin with improvement of his neurological deficit. Cardiac MRI later showed moderate atrioventricular valve regurgitation (AVVR) and his ejection fraction (EF) was 33%. Patient is currently managed with Warfarin as well as congestive heart failure (CHF) guideline-directed medical therapy. DISCUSSION: Patients treated surgically with palliative Fontan's procedure are prone to thromboembolic events [1,2] due to coagulation abnormalities associated with hepatic congestion and increased right-to-left shunting. They need to be chronically anticoagulated [3]. Heart failure usually also ensues due to sudden drop in preload filling of the chronically volume-overloaded ventricle leading to significantly reduced cardiac output. CONCLUSIONS: Understanding the new cardiac hemodynamic physiology after corrective surgeries and their complications, is pivotal for timely diagnosis and treatment of adult congenital heart disease patients. Reference #1: Odegard KC, McGowan FX Jr, Zurakowski D, et al. Procoagulant and anticoagulant factor abnormalities following the Fontan procedure: increased factor VIII may predispose to thrombosis. J Thorac Cardiovasc Surg. 2003;125(6):1260-1267. doi:10.1016/s0022-5223(02)73605-2 Reference #2: Wilson DG, Wisheart JD, Stuart AG. Systemic thromboembolism leading to myocardial infarction and stroke after fenestrated total cavopulmonary connection. Br Heart J. 1995;73(5):483-485. doi:10.1136/hrt.73.5.483 Reference #3: Alsaied T, Alsidawi S, Allen CC, Faircloth J, Palumbo JS, Veldtman GR. Strategies for thromboprophylaxis in Fontan circulation: a meta-analysis. Heart. 2015;101(21):1731-1737. doi:10.1136/heartjnl-2015-307930 DISCLOSURES: No relevant relationships by John Abdelmalek, source=Web Response No relevant relationships by Saif El Naser El Nawaa, source=Web Response No relevant relationships by Mohamed Elmassry, source=Web Response No relevant relationships by pooja sethi, source=Web Response No relevant relationships by Victor Test, source=Web Response

Multiscale Modeling of Superior Cavopulmonary Circulation: Hemi-Fontan and Bidirectional Glenn Are Equivalent

Superior cavopulmonary circulation (SCPC) can be achieved by either the Hemi-Fontan (hF) or Bidirectional Glenn (bG) connection. Debate remains as to which results in best hemodynamic results. Adopting patient-specific multiscale computational modeling, we examined both the local dynamics and global physiology to determine if surgical choice can lead to different hemodynamic outcomes. Six patients (age: 3-6 months) underwent cardiac magnetic resonance imaging and catheterization prior to SCPC surgery. For each patient: (1) a finite 3-dimensional (3D) volume model of the preoperative anatomy was constructed to include detailed definition of the distal branch pulmonary arteries, (2) virtual hF and bG operations were performed to create 2 SCPC 3D models, and (3) a specific lumped network representing each patient's entire cardiovascular circulation was developed from clinical data. Using a previously validated multiscale algorithm that couples the 3D models with lumped network, both local flow dynamics, that is, power loss, and global systemic physiology can be quantified. In 2 patients whose preoperative imaging demonstrated significant left pulmonary artery (LPA) stenosis, we performed virtual pulmonary arterioplasty to assess its effect. In one patient, the hF model showed higher power loss (107%) than the bG, while in 3, the power losses were higher in the bG models (18-35%). In the remaining 2 patients, the power loss differences were minor. Despite these variations, for all patients, there were no significant differences between the hF and bG models in hemodynamic or physiological outcomes, including cardiac output, superior vena cava pressure, right-left pulmonary flow distribution, and systemic oxygen delivery. In the 2 patients with LPA stenosis, arterioplasty led to better LPA flow (5-8%) while halving the power loss, but without important improvements in SVC pressure or cardiac output. Despite power loss differences, both hF and bG result in similar SCPC hemodynamics and physiology outcome. This suggests that for SCPC, the pre-existing patient-specific physiology and condition, such as pulmonary vascular resistance, are more deterministic in the hemodynamic performance than the type of surgical palliation. Multiscale modeling can be a decision-assist tool to assess whether an extensive LPA reconstruction is needed at the time of SCPC for LPA stenosis.

Abstract 17224: Volatile Anesthetic Agents Increase Cerebral to Systemic Blood Flow Ratio in Children Undergoing Cardiac Magnetic Resonance Imaging

Introduction: Cardiac magnetic resonance imaging (CMR) can reliably assess hemodynamics in children. Anesthetic agents may affect cerebral blood flow (CBF) and change the cerebral to systemic perfusion ratio. Hypothesis: Volatile anesthetic agents cause significant cerebral vasodilation resulting in descending aorta (DAo) flow reversal. Methods: Blood flow was measured in patients who underwent cine phase contract velocity mapping during CMR (1.5T, Philips Ingenia, Amsterdam, The Netherlands) with or without general anesthesia (GA) at our institution. Patients with a known cause for flow reversal in DAo (e.g. aortic insufficiency, aorto-pulmonary shunt/collaterals) or brain pathology were excluded. Flows in superior vena cava (SVC, surrogate for CBF), ascending aorta (AAo, measure of cardiac output), and DAo (measure of lower body perfusion) were analyzed. Measures of central tendency, standard deviation, correlation coefficient and Student’s t-test were calculated. Variables including anesthetic agents, body surface area (BSA), mechanical ventilator parameters and vital signs were assessed. Results: A total of 93 CMR scans were performed with GA (n=43, age 3 m to 15 y, BSA 0.29-2.4 m 2 ) or without GA (n=50, 2 w to 21 y, BSA 0.2-2.89 m 2 ). There was significant flow reversal in DAo (mean 7.62% +/- SD 7%) in GA group using volatile agents compared to non-GA patients (1.16% +/- 1.78%; p-value <0.001). SVC flow was higher in GA (1.66+/-1.02 ml/min/m 2 ) than non-GA patients (1.28+/-0.53 ml/min/m 2 ) but did not reach statistical significance (p=0.06). GA group had significantly higher SVC (cerebral blood) to AAo flow (cardiac output) ratio (0.53 +/- 0.13) than non-GA group (0.44 +/- 0.17; p=0.003), probably from increased CBF from cerebral vasodilation by volatile anesthetic agents. Patients with BSA >1.2 m 2 and GA (0.84 +/- 0.27) had a tendency to have higher SVC/DAo flow ratio compared to non-GA (0.69 +/- 0.3; p = 0.06) patients. There was a positive correlation between the end tidal CO 2 and SVC flow (r 0.486, R 2 0.236). Conclusions: The flow rates of SVC, AAo and DAo using CMR must be interpreted with caution in children, taking into account the effects of GA on the cerebral and lower body perfusion. This difference may be relevant in patients with congenital heart disease, especially with cavo-pulmonary and Fontan circulation.

Cardiac Magnetic Resonance Imaging of Mechanical Cavopulmonary Assistance

Mechanical circulatory support (MCS) options are limited for patients with dysfunctional single ventricle physiology. To address this unmet clinical need, we are developing an axial-flow blood pump to provide mechanical assistance to the cavopulmonary circulation. In this study, we investigate the use of high-resolution cardiac magnetic resonance imaging (MRI) to visualize the complex fluid flow conditions of mechanical circulatory assist in two patient-specific Fontan anatomies. A three-bladed axial-flow impeller coupled to a supportive cage with a four-bladed diffuser was positioned in the inferior vena cava (IVC) of each Fontan anatomy. Cardiac magnetic resonance (CMR) imaging and power efficiency studies were conducted at physiologic relevant parameters with cardiac outputs of 2, 3, and 4 L/min with impeller rotational speeds of 2000 and 4000 rpm. The axial-flow impeller was able to generate improved flow in the total cavopulmonary connection (TCPC). The higher rotational speed was able to redistribute flow in the TCPC anastomosis aiding in removing stagnant blood. No retrograde flow was observed or measured in the superior vena cava (SVC). As an extension of the CMR data, a scalar stress analysis was performed on both models and found a maximum scalar stress of approximately 42 Pa for both patient anatomies. The power efficiency experiments demonstrated a maximum energy gain of 8.6 mW for TCPC Anatomy 1 and 12.58 mW for TCPC Anatomy 2 for a flow rate of 4 L/min and at 4000 rpm. These findings support the continued development of axial blood pumps for mechanical cavopulmonary assist.

Determination of the Frequency of Right and Left Internal Mammary Artery Embolization in Single Ventricle Patients: A Two-Center Study.

Embolization of systemic to pulmonary artery collaterals to regulate pulmonary arterial flow or pressure of the cavopulmonary circulation in patients with single ventricle is a common practice. The relative incidence and impact of this practice on future interventions like coronary artery bypass grafting is poorly understood. This study aims to evaluate the frequency and implications of internal mammary artery (IMA) embolization in the single ventricle (SV) population. A retrospective chart review was performed of SV patients who underwent cardiac catheterization before and after Fontan procedure between February 2007 and 2017. Data were collected from two tertiary care centers in the Midwest. Of the 304 SV patients, 62 (20.4%) underwent embolization of one or more IMAs, whereas 242 (79.6%) did not. The rate of embolization of IMA was 40.5% in one center and 14.5% in the second center. Among patients who received IMA embolization, left internal mammary artery (LIMA) embolization was seen in 6 (9.7%) patients. Majority of patients underwent either right internal mammary artery (RIMA) embolization (n = 25; 40.3%) or RIMA and LIMA embolization (n = 27; 43.5%). IMA embolization in SV patients is common. Embolizing IMAs early in life will likely eliminate a valuable graft option for coronary artery bypass grafting should it be required in the future care of these patients. Multi-center, prospective, nation-wide studies are warranted to examinecoronary artery disease in the SV population and true frequency of IMA embolization. Delineation of which IMAs were embolized is a necessary in surgical and cardiac intervention national data, such as Society of Thoracic Surgeons (STS) database. All measures should be taken to preserve IMAs patency, if deemed feasible and safe.

Pump in Parallel-Mechanical Assistance of Partial Cavopulmonary Circulation Using a Conventional Ventricular Assist Device.

Mechanical assistance of systemic single ventricle is effective in pulling blood through a cavopulmonary circuit. In patients with superior cavopulmonary connection, this strategy can lead to arterial desaturation secondary to increased inferior caval flow. We hypothesized that overall augmentation in cardiac output with mechanical assistance compensates for the drop in oxygen saturation thereby maintaining tissue oxygen delivery (DO2). Bidirectional Glenn (BDG) was established in seven swine (25 kg) after a common atrium had been established by balloon septostomy. Mechanical circulatory assistance of the single ventricle was achieved using an axial flow pump with ventricular inflow and aortic outflow. Cardiac output, mean pulmonary artery pressure (PAP), common atrial pressure (left atrial pressure [LAP]), arterial oxygen saturation (SaO2), partial pressure of arterial oxygen (PaO2), and DO2 were compared between assisted and nonassisted circulation. Significant augmentation of cardiac output was achieved with mechanical assistance in BDG circulation (BDG: median [interquartile range {IQR}], 0.8 [0.9-1.15] L/min versus assisted BDG: median [IQR], 1.5 [1.15-1.7] L/min; p = 0.05). Although oxygen saturations and PaO2 trended to be lower with assistance (SaO2; BDG: median [IQR], 43% [32-57%]; assisted BDG: median [IQR], 32% [24-35%]; p = 0.07) (PaO2; BDG: median [IQR], 24 [20-30] mm Hg; assisted BDG: median [IQR], 20 [17-21] mm Hg; p = 0.08), DO2 was unchanged with mechanical assistance (BDG: median [IQR], 94 [35-99] ml/min; assisted BDG: median [IQR], 79 [63-85] ml/min; p = 0.81). No significant change in the LAP or PAP was observed. In the setting of superior cavopulmonary connection/single ventricle, the systemic ventricular assistance with a ventricular assist device (VAD) leads to increase in cardiac output. Arterial oxygen saturations however may be lower with mechanical assistance, without any change in DO2.

2 Suitability of univentricular patients for cardiac resynchronisation therapy

Introduction In 2014 the Paediatric And Congenital Electrophysiology Society (PACES) and Heart Rhythm Society (HRS) published expert consensus statement regarding arrhythmia management in congenital heart disease, including Cardiac Resynchronisation Therapy (CRT) indications for adult congenital heart disease (ACHD) patients. These guidelines recommend CRT in univentricular hearts for those who have an impaired ventricle (EF ≤35%) with QRSd ≥150 ms, ventricular dilatation and NYHA II-IV[IIa, C]. Methods Retrospective analysis for EF, QRSd and NYHA status, from 211 patients with a Fontan circulation under specialist ACHD follow-up. Results Univentricular functional data was available for 94% (198, 84 CMR and 114 echo). 10 (5%) patients had EF ≤35%. QRSd was available for 91% (193). 5 (3%) had QRSd≥150 ms. 2 patients were identified with both EF ≤35% and QRSd ≥150 ms, fulfilling indications for CRT. One patient was NYHA IV, tricuspid atresia with an atriopulmonary fontan and subsequent conversion to total cavopulmonary circulation (TCPC). The second patient (NYHA II) had right atrial isomerism with pulmonary atresia and an unfenestrated TCPC. Conclusions If recent HRS CRT guidelines are applied to this large adult Fontan population there are very few candidates for CRT. Guidelines should be interpreted with caution. In virtually all cases, CRT device implantation in the adult Fontan will require a cardiac surgical approach associated with significant morbidity and mortality. The decision to implant CRT in Fontan patients is therefore complex and requires discussion in a combined ACHD electrophysiology MDT with careful consideration of patient anatomy and previous surgery

Vortical flow characteristics of mechanical cavopulmonary assistance: Pre- and post-swirl dynamics.

Surgical optimization of the cavopulmonary connection and pharmacological therapy for dysfunctional Fontan physiology continue to advance, but these treatment approaches only slow the progression of decline to end-stage heart failure. The development of a mechanical cavopulmonary assist device will provide a viable therapeutic option in the bridging of patients to transplant or to stabilization. We hypothesize that rotational blood flow, delivered by an implantable axial flow blood pump, could effectively assist the venous circulation in Fontan patients by mimicking vortical blood flow patterns in the cardiovascular system. This study investigated seven new models of mechanical cavopulmonary assistance (single and dual-pump assist), created combinations of pump designs that deliver counter rotating vortical flow conditions, and analyzed pump performance, velocity streamlines, swirling strength, and energy augmentation in the cavopulmonary circuit for each support scenario. The model having an axial clockwise-oriented impeller in the inferior vena cava and an axial counterclockwise-oriented impeller rotating in the superior vena cava outperformed all of the support scenarios by enhancing the energy of the cavopulmonary circulation an average of 10.3% over the entire flow range and a maximum of 27.4% at %the higher flow rates. This research will guide the development of axial flow blood pumps for Fontan patients and demonstrated the high probability of %a cardiovascular benefit using counter rotating pumps in a dual support scenario, but found that this is dependent upon the patient-specific cavopulmonary anatomy.

Institutional Experience of Assisting Cavopulmonary Circulation With Central Systemic Artery-to-Central Systemic Vein Shunt.

Patients who have undergone a previous bidirectional superior cavopulmonary anastomosis and have hypoxemia and anatomy considered unsuitable for the Fontan completion present a difficult subset. We performed common carotid artery-to-internal jugular vein (CCA-IJV) shunt in these patients. Between January 2010 and January 2015, eight patients underwent a CCA-IJV shunt. Their records were analyzed retrospectively. There were no early deaths. The baseline arterial saturation prior to the shunt procedure was median 67% (range 60%-72%), which increased to median 83% (range 80%-90%) after the procedure. The preoperative arterial oxygen partial pressure (Pao 2) ranged from 30 to 49 mm Hg (median 40 mm Hg). The hematocrit dropped from a preoperative median of 65% (range 55%-72%) to a median of 45% (range 42%-48%) after the procedure. Median intensive care unit stay was 2.5 days, and the median hospital stay was 7 days. Median follow-up was 24 months. At the last follow-up, these patients were classified in New York Heart Association class II. In a selected group of patients who are considered to be unsuitable for completion of Fontan circulation following superior cavopulmonary anastomosis, creation of a CCA-IJV shunt may be helpful to improve saturations and improve ventricular function.

Pulmonary vasodilator therapy in the failing Fontan circulation: rationale and efficacy.

The Fontan operation is the final step of palliation for patients with a functionally single ventricle. Since its introduction in the 1970s, the Fontan surgery has become part of a successful surgical strategy that has improved single ventricle mortality. In recent years, we have become more aware of the limitations and long-term consequences of the Fontan physiology. Pulmonary vascular resistance plays an important role in total cavopulmonary circulation, and has been identified as a potential therapeutic target to mitigate Fontan sequelae. In this review, we will discuss the results of different pulmonary vasodilator trials and the use of pulmonary vasodilators as a treatment strategy for Fontan patients.

Experimental Measurements of Energy Augmentation for Mechanical Circulatory Assistance in a Patient-Specific Fontan Model

A mechanical blood pump specifically designed to increase pressure in the great veins would improve hemodynamic stability in adolescent and adult Fontan patients having dysfunctional cavopulmonary circulation. This study investigates the impact of axial-flow blood pumps on pressure, flow rate, and energy augmentation in the total cavopulmonary circulation (TCPC) using a patient-specific Fontan model. The experiments were conducted for three mechanical support configurations, which included an axial-flow impeller alone in the inferior vena cava (IVC) and an impeller with one of two different protective stent designs. All of the pump configurations led to an increase in pressure generation and flow in the Fontan circuit. The increase in IVC flow was found to augment pulmonary arterial flow, having only a small impact on the pressure and flow in the superior vena cava (SVC). Retrograde flow was neither observed nor measured from the TCPC junction into the SVC. All of the pump configurations enhanced the rate of power gain of the cavopulmonary circulation by adding energy and rotational force to the fluid flow. We measured an enhancement of forward flow into the TCPC junction, reduction in IVC pressure, and only minimally increased pulmonary arterial pressure under conditions of pump support.

Leaving antegrade pulmonary blood flow results in reversal of flow in the azygous vein and decompression of the cavopulmonary circulation: mechanism of cyanosis defined with cardiac magnetic resonance imaging

We report the case of a 2.5-year-old patient with single-ventricle physiology who underwent cardiac magnetic resonance study for cyanosis after Kawashima operation. Magnetic resonance imaging study showed a veno-venous collateral redirecting systemic venous flow, responsible for cyanosis.

Upper body central venous catheters in pediatric cardiac surgery

A central venous catheter located in the jugular or subclavian vein provides rapid, reliable vascular access for pediatric heart surgery. However, intravascular catheters are associated with vessel injury. Stenosis or thrombosis of central veins in the upper body can lead to 'superior vena cava syndrome' with markedly elevated venous pressures in the head and neck, causing facial swelling and headaches. This complication may be especially serious for patients with superior cavopulmonary (Glenn) or total cavopulmonary (Fontan) circulation. The authors hypothesized that upper body central line placement would be associated with a low risk of venous thrombosis or stenosis. A three-year retrospective review of infant and univentricular cardiac procedures at a single institution was performed. Two hundred and thirty-five consecutive cardiac surgical patients <1 year of age or undergoing palliation for univentricular cardiac anatomy up to five years of age during January 2010 to December 2012 were included in this study. Upper body central lines are routinely placed by the anesthesiologist after induction of anesthesia for pediatric cardiac surgery at the study institution. The major exception is existing central venous access via an umbilical vein or femoral vein. Patients <2 years of age received a 4.0-French, 5-cm double-lumen central line [Cook Medical polyurethane, no antibiotic or heparin coating]. Those over two years of age received a 5.0-French, 8-cm triple lumen central line [Cook Medical polyurethane, no antibiotic or heparin coating]. A retrospective review of charts, hospital reports, echocardiographic studies, and cardiac catheterization studies was performed. The combined population of infants <1 year of age and patients <5 years of age with functional univentricular hearts totaled 235 patients who underwent 261 cardiac surgical operations. In this cohort of 261 cases, 171 size 4.0 or 5.0-French upper body central lines were inserted. A total of 158 right internal jugular vein catheters were placed. Two left internal jugular lines, two left subclavian lines, and nine right subclavian lines were placed in this population after failure to obtain right internal jugular access. Due to the small sample size (N = 13), the central lines not placed in the right internal jugular vein were excluded from further review. Two cases with right internal jugular venous lines were excluded due to death (without known stenosis or thrombosis) with the line in place. Twenty-three size 4.0- or 5.0-French right internal jugular central venous lines were placed in patients over one year of age (range 1.1-4.3 years) having modified Glenn- or Fontan-type surgery. The central lines were removed with a median of 1.4 days after insertion (range 0.7-8.2 days) for these older children, compared with a median of 4.2 days of age (range 0.3-19.3 days) for the 133 children <1 year of age. Retrospective chart review of nursing notes, progress notes, cardiology notes, discharge summaries, echocardiographic reports, and cardiac catheterization reports for all patients who received an upper body central venous line (internal jugular or subclavian) showed no definitive diagnosis of an upper body venous stenosis or thrombosis related to the central venous line. A further targeted review of echocardiographic and cardiac catheterization studies for univentricular cardiac patients failed to show stenosis or thrombosis of a vessel associated with upper body central line placement. This study describes one institution's experience with routine upper body central venous catheter placement for neonatal and infant cardiac surgery as well as univentricular cardiac palliation (Glenn and Fontan procedures) with minimal risk of clinically significant catheter-associated vessel thrombosis or stenosis. No upper body central venous stenosis or thrombosis was detected in association with perioperative catheter placement in the upper body central venous system, primarily the right internal jugular vein in 156 cases. Right internal jugular central line placement for infant cardiac surgery can be utilized with a low risk of direct venous thrombosis or stenosis.

Progressive cyanosis following Kawashima operation: slow resolution after redirection of hepatic veins

Progressive cyanosis often develops following Kawashima operation in patients with left atrial isomerism, interrupted inferior vena cava and hepatic veins draining to the atria. Knowledge on the timing and extend of resolution following hepatic venous redirection is sparse. A girl developed progressing cyanosis following Kawashima operation at the age of ten months. Arterial oxygen saturations at rest dropped to 60-65%. Surgical redirection of hepatic veins into the cavopulmonary circulation at the age of three years had no immediate effect. However, arterial oxygen saturations increased gradually over nine months to 90-93% and 95-100% after three years.

A Viable Therapeutic Option: Mechanical Circulatory Support of the Failing Fontan Physiology

A blood pump specifically designed to augment flow from the great veins through the lungs would ameliorate the poor physiology of the failing univentricular circulation and result in a paradigm shift in the treatment strategy for Fontan patients. This study is the first to examine mechanical cavopulmonary assistance with a blood pump in the inferior vena cava (IVC) and hepatic blood flow. Five numerical models of mechanical cavopulmonary assistance were investigated using a three-dimensional, reconstructed, patient-specific Fontan circulation from magnetic resonance imaging data. Pressure flow characteristics of the axial blood pump, energy augmentation calculations for the cavopulmonary circulation with and without pump support, and hemolysis estimations were determined. In all of the pump-supported scenarios, a pressure increase of 7-9.5 mm Hg was achieved. The fluid power of the cavopulmonary circulation was also positive over the range of flow rates. No retrograde flow from the IVC into the hepatic circulation was evident during support cases. Vessel suction risk, however, was found for greater operating rotational speeds. Fluid shear stresses and hemolysis predictions remained at acceptable levels with normalized index of hemolysis estimations at 0.0001 g/100 L. The findings of this study support the continued design and development of this blood pump technology for Fontan patients with progressive cardiovascular insufficiency. Validation of these flow and performance predictions will be completed in the next round of experimental testing with blood bag evaluation.

Challenges in Longer-Term Mechanical Support of Fontan Circulation in Sheep

Single ventricle congenital heart defects are usually palliated with the end result of a Fontan circulation. Despite improving results, this circulation is still associated with long-term failure. We previously developed an animal model of mechanical cavopulmonary circulation support that was successful in the acute and mid-term period. In the current study, we evaluated longer support durations in five Western-breed sheep. Through a right thoracotomy we instituted mechanical support from the inferior vena cava to the pulmonary artery, using a Heartmate II axial flow pump (Thoratec Corp., Pleasanton, CA). Postoperatively, the animals were anticoagulated with heparin iv. Hemodynamics, pump flow, anticoagulation, and hepatic and renal function were monitored daily. All animals survived the operation. Signs of moderate liver and kidney injury in general reversed quickly. Two animals had a fatal pump thrombosis. When anticoagulation was effective, hemodynamics and pump flow were maintained to normal values. Effective anticoagulation was difficult to achieve because of the high variability in response to heparin. Survival up to 18 days was accomplished. This study is the longest reported survival of animals with a mechanically assisted cavopulmonary circulation. The performance of the Thoratec Heartmate II has been good, but the issue of effective anticoagulation has not yet been solved.