Cardiac MRI-Derived Inferior Vena Cava Cross-Sectional Area Correlates with Measures of Fontan-Associated Liver Disease

There is currently no clear consensus on screening techniques to evaluate the presence or severity of Fontan-associated liver disease (FALD). Cardiac MRI (CMR) is used routinely for post-Fontan surveillance, but CMR-derived measures that relate to the severity of FALD are not yet defined. This was a cross-sectional single-center study of post-Fontan patients who underwent a CMR. CMR exams were re-analyzed by a single pediatric cardiologist. Surrogates of FALD included Gamma-Glutamyl Transferase (GGT), Fibrosis-4 laboratory score (FIB-4), and imaging findings. Findings consistent with cirrhosis on liver ultrasound included increased liver echogenicity and/or nodularity. Statistical analyses were performed to investigate potential relationships between CMR parameters and markers of FALD. Sixty-one patients were included. A larger inferior vena cava cross-sectional area (IVC-CSA) indexed to height was significantly associated with a higher FIB-4 score (Spearman's ρ = 0.28, p = 0.04), a higher GGT level (Spearman's ρ = 0.40, p = 0.02), and findings consistent with cirrhosis on liver ultrasound (OR 1.17, 95% CI: (1.01, 1.35), p = 0.04). None of the other CMR parameters were associated with markers of FALD. A larger indexed IVC-CSA was associated with higher systemic ventricle end-diastolic pressure (EDP) on cardiac catheterization (Spearman's ρ = 0.39, p = 0.018) as well as older age (Spearman's ρ = 0.46, p =  < 0.001). Indexed IVC-CSA was the only CMR parameter that was associated with markers of FALD. This measure has the potential to serve as an additional non-invasive tool to improve screening strategies for FALD.

Fontan Heart: Insight Into the Physiological Role of the Right Heart

BACKGROUND

Cardiac output (CO) is almost normal in children born without a functional right ventricle (RV), and a Fontan repair, so why is RV dysfunction such a clinical problem? We tested the hypotheses that increased pulmonary vascular resistance (PVR) is the dominant factor and volume expansion by any means is of limited benefit.

METHODS

We removed the RV from a previously used MATLAB model and altered vascular volume, venous compliance (Cv), PVR, and measures of left ventricular (LV) systolic and diastolic function. CO and regional vascular pressures were the primary outcome measures.

RESULTS

RV removal decreased CO by 25%, and raised mean systemic filling pressure (MSFP). A 10 mL/kg increase in stressed volume only moderately increased CO with or without the RV. Decreasing systemic Cv increased CO but also markedly increased pulmonary venous pressure. With no RV, increasing PVR had the greatest effect on CO. Increasing LV function had little benefit.

CONCLUSIONS

Model data indicate that increasing PVR dominates the decrease in CO in Fontan physiology. Increasing stressed volume by any means only moderately increased CO and increasing LV function had little effect. Decreasing systemic Cv unexpectedly markedly increased pulmonary venous pressures even with the RV intact.

Investigating the hemodynamics of Berlin Heart EXCOR support in Norwood patients across diverse clinical scenarios with computational modeling

BACKGROUND

Infants with single-ventricle (SV) physiology undergo the 3-stage Fontan surgery. Norwood patients, who have completed the first stage, face the highest interstage mortality. The Berlin Heart EXCOR (BH), a pediatric pulsatile ventricular assist device, has shown promise in supporting these patients. However, clinical questions regarding device configurations prevent optimal support.

METHODS

We developed a combined idealized mechanics-lumped parameter model of a Norwood patient and simulated two additional patient-specific cases: pulmonary hypertension (PH) and post-operative treatment with milrinone. We quantified the effects of BH support across different device volumes, rates, and inflow connections on patient hemodynamics and BH performance.

RESULTS

Increasing device volume and rate increased cardiac output, but with unsubstantial changes in specific arterial oxygen content. We identified distinct SV-BH interactions that may impact patient myocardial health and contribute to poor clinical outcomes. Our results suggested BH settings for patients with PH and for patients treated post-operatively with milrinone.

CONCLUSIONS

We present a computational model to characterize and quantify patient hemodynamics and BH support for infants with Norwood physiology. Our results emphasized that oxygen delivery does not increase with BH rate or volume, which may not meet patient needs and contribute to suboptimal clinical outcomes. Our findings demonstrated that an atrial BH may provide optimal cardiac loading for patients with diastolic dysfunction. Meanwhile, a ventricular BH decreased active stress in the myocardium, and countered the effects of milrinone. Patients with PH showed greater sensitivity to device volume. In this work, we demonstrate the adaptability of our model to analyze BH support across varied clinical situations.

Impact of Home Monitoring Program and Early Gastrostomy Tube on Interstage Outcomes following Stage 1 Norwood Palliation

Nutritional management and home monitoring programs (HMPs) may be beneficial for improving interstage morbidity and mortality following stage I Norwood palliation (S1P) for hypoplastic left heart syndrome (HLHS). We recognized an increasing trend towards early feeding gastrostomy tube (GT) placement prior to discharge in our institution, and we aimed to investigate the effect of HMPs and GTs on interstage mortality and growth parameters. Single-institutional review at a tertiary referral center between 2008 and 2018. Individual patient charts were reviewed in the electronic medical record. Those listed for transplant or hybrid procedures were excluded. Baseline demographics, operative details, and interstage outcomes were analyzed in GT and non-GT patients (nGT). Our HMP was instituted in 2009, and patients were analyzed by era: I (early, 2008-2012), II (intermediate, 2013-2016), and III (recent, 2017-2018). 79 patients were included in the study: 29 nGTs and 50 GTs. GTs had higher number of preoperative risk factors more S1P complications, longer ventilation times, longer lengths of stay, and shorter times to readmission. There were no differences in interstage mortality or overall mortality between groups. There was one readmission for a GT-related issue with no periprocedural complications in the group. Weight gain doubled after GT placement in the interstage period while waiting periods for placement decreased across Eras. HMPs and early GTs, especially for patients with high-risk features, provide a dependable mode of nutritional support to optimize somatic growth following S1P.

The effect of single ventricle congenital heart disease on recurrence risk of pneumatosis intestinalis in neonates

PURPOSE

Congenital heart disease (CHD) is a risk factor for the development of pneumatosis intestinalis (PI). Patients with single ventricle physiology (SVP) may be at higher risk of developing PI secondary to variations in systemic blood flow which affect bowel perfusion when compared to patients with biventricular physiology (BVP). We hypothesized that patients with SVP would have increased risk of recurrent PI.

METHODS

A retrospective review was done from 10/2014 through 05/2020 with patients that met the following criteria: CHD, radiographic evidence of PI, and less than 1 year of age. Groups were divided based on ventricular physiology. Primary outcome was radiographic recurrence of PI and secondary outcomes were average antibiotic duration, NPO duration, median length of stay, need for GI operation, and death from PI.

RESULTS

A total of 51 patients were included, 34 with SVP and 17 with BVP. 26.47% of SVP had recurrence of PI whereas no BVP experienced a recurrence of PI. There was no significant difference in any of the secondary outcomes.

CONCLUSION

Our data suggest that patients with SVP are more likely to have recurrence of radiographic PI. We may need to consider patients with SVP that get PI as their own separate group.

Screening and Evaluation of Neurodevelopmental Impairments in Infants Under 6 Months of Age with Congenital Heart Disease

Clinical evaluation of neurodevelopmental impairments before 6 months of age is needed in congenital heart disease (CHD) to promote early referral to developmental interventions. The objective was to identify the risk of cerebral palsy (CP) and to compare neurodevelopment outcomes in infants with and without CHD. In a longitudinal study, 30 infants with CHD and 15 infants without CHD were assessed at 1 month, 3 months, and 6 months of age. Included measures were General Movement Assessment (GMA), Test of Infant Motor Performance (TIMP) and the Bayley Scale of Infant Development, third edition (Bayley-III), selected to identify the risk of CP, document neurodevelopmental impairments and infants' eligibility for early intervention services. Abnormal GMA categories were found in the CHD group where 48% had poor repertoire and 15% were at high risk of CP. At 3 months of age, CHD group had significantly lower TIMP scores compared to infants without CHD [t(41) = 6.57, p = 0.01]. All infants in the study had higher Bayley-III scores at 6 months than at 3 months of age. Infants with CHD had lower gross motor, fine motor and cognitive Bayley-III scores compared to their peers without CHD. Over time infants without CHD outperformed the CHD group in the gross motor skills [F_(1,41) = 11.76, p = .001]. Higher prevalence of abnormal GMs, lower TIMP and Bayley-III were found in infants with single ventricle physiology compared to two-ventricle physiology. The risk of CP exists in infants with CHD, and these infants have worse outcomes compared to their peers without CHD. These differences are intensified in the single ventricle population.Clinical Trial Registration National Institute of Health, Unique identifier: NCT03104751; Date of registration-April 7, 2017.

Heart transplantation for patients with single ventricle physiology

Background

There is a growing population of palliated and unpalliated single ventricle physiology patients for whom heart transplantation is the only treatment option available. There is a paucity of reports of heart transplantation in this challenging and growing subset of patients from our part of the world. The purpose of the article is to briefly review our experience in the subgroup and compare it with the available literature.

Methods

This was a single-institution retrospective observational study of 16 patients with single ventricle physiology who were transplanted between 2016 and 2019 and their outcomes. The study groups were divided into those with ventricular dysfunction (group 1), who fare substantially better than those with normal ventricular function (group 2) whose short-term outcomes were poorer. Worsening cyanosis, poor candidature for completion Fontan procedure due to severe atrioventricular valve regurgitation or pulmonary artery anatomy, protein-losing enteropathy, plastic bronchitis, and worsening systemic venous congestion are indications in those with normal ventricular function.

Results

Patients with ventricular dysfunction as the main indication had excellent early survival with no early mortality compared to 40% mortality in patients with normal ventricular function. Patients who survived to leave the hospital had however similar long-term outcomes. Two patients with protein-losing enteropathy resolved completely by one month. Normal ventricular function, pulmonary artery stenting, early Fontan failure (6 months), ascites, and need for desensitization were risk factors for early mortality. After the early acute phase of increased risk, the mortality risk plateaued off.

Conclusion

Transplantation in patients with single ventricle and ventricular dysfunction can be offered with a good early and late outcome. There is a need to have multi-institutional and multi-disciplinary collaboration along with work in basic sciences to better understand the effects of failed Fontan physiology with normal ventricular function.

Aortopulmonary Collaterals in Single Ventricle Physiology: Variation in Understanding Occlusion Practice Among Interventional Cardiologists

Although aortopulmonary collaterals (APCs) frequently develop in patients with single ventricle palliation, there is a lack of understanding of pathophysiology, natural history, and outcomes with no universal guidelines for management and interventional practice. We conducted a study to assess the views held by interventional congenital cardiologists regarding the hemodynamic impact of APCs in patients with single ventricle palliation, and their embolization practice. An electronic survey using the Pediatric Interventional Cardiology Symposium (PICS) mailing list was conducted between February and March 2019 with one reminder sent 2 weeks after initial invitation for participation. Of the 142 interventional cardiologist respondents, 95 (66.9%) reside in North America and 47 (33.1%) worldwide. We elected to exclude the data from interventionalists outside North America in this analysis as it was not representative of worldwide practice. Hypoxemia was considered to be the most common trigger for development of APCs by 56 (58.9%) respondents. After completion of total cavopulmonary connection, 30 (31.6%) respondents reported the APC burden stays the same while 31 (32.6%) feel it decreases. In evaluating the burden of APC flow, only 4 (4.2%) reported measuring oxygen saturation at different pulmonary artery segments, 21 (22.1%) perform segmental aortic angiograms, and 18 (19%) perform selective bilateral subclavian artery angiograms. A majority of respondents, 71 (74.7%), occlude the feeder vessel at different locations, while 10 (10.5%) occlude only the origin of the vessel. Our study demonstrates significant variation in the understanding of the cause and prognosis of APCs in patients with single ventricle palliation. Furthermore, there is variation in the approach for diagnosis and management among interventional cardiologists. Further studies are required to improve understanding of APCs and develop universal management guidelines.

Outcomes after the Fontan operation in the Middle East: A large Saudi Arabian single centre experience

BACKGROUND

Fontan outcomes data from large volume Middle Eastern Centres are lacking. We report our experience after the Fontan operation from a tertiary cardiac centre in Saudi Arabia.

METHOD

All 458 consecutive patients who had Fontan surgery 1986 through 2015 at the Prince Sultan Cardiac Centre, Riyadh [PSCC], Saudi Arabia, were evaluated for baseline, early and late post-operative outcomes and their uni and multivariate determinants.

RESULTS

The mean age at Fontan operation was 7 years [IQR 4.8-9.0]. The most common anatomic diagnoses were tricuspid atresia (104 [23%]) and double-inlet left ventricle (81 [18%]). Only 3 patients in the present series had hypoplastic left heart syndrome [HLHS]. Early mortality [i.e. during Fontan surgical admission] was 3.1%. At late follow-, 35 (8%) patients were lost to follow up. The 1, 5, 10, 20 and 30 year survival was 96%, 94%, 93% and 85%, respectively. In the modern surgical era, 5, 10 and 15 year survival were 96%, 95% and 93% respectively. Univariate determinants of death or transplant were hypoalbuminemia, elevated NtProBNP >500, surgical era prior to 1999, the lack of Fontan fenestration, and prior atriopulmonary Fontan [APF] procedure. On multivariate analysis, surgical era before 1999 and prior APF procedure were independently associated with death or transplant.

CONCLUSIONS

Fontan patients from this large volume Middle Eastern centre have comparable early and late mortality outcomes compared to prior published reports. Rigorous selection criteria at the time of Fontan, and Fontan specific dedicated care teams are likely contributors to this success.

The Adult Patient with a Fontan

The authors summarize the most important anatomic and physiologic substrates of Fontan circulation. Common anatomic substrates include hypoplastic left heart syndrome, tricuspid atresia, double inlet left ventricle, and unbalanced atrioventricular septal defects. After the Fontan operation exercise capacity is limited and the key hemodynamic drivers is limited preload due to a relatively fixed pulmonary vascular resistance. The authors provide contemporary data on survival, morbidity, and need for reintervention. Operative morality is now expected to be less than 1% and 30 year survival approximately 89%. The authors delineate potential therapeutic approaches for the potential late complications.

Computational Modeling to Support Surgical Decision Making in Single Ventricle Physiology

Many of the advances in congenital heart surgery were built upon lessons and insights gained from model simulations. While animal and mock-circuit models have historically been the main arena to test new operative techniques and concepts, the recognition that complex cardiovascular anatomy and circulation can be modeled mathematically ushered a new era of collaboration between surgeons and engineers. In 1996, the computational age in congenital heart surgery began when investigators in London and Milan tapped the power of the computer to simulate the Fontan procedure and introduced operative improvements. Since then, computational modeling has led to numerous contributions in congenial heart surgery as continuing sophistication and advances in numerical and imaging methods furthered the ability to refine anatomic and physiologic details. Idealized generic models have given way to precise patient-specific simulations of the 3-dimensional anatomy, reconstructed circulation, affected hemodynamics, and altered physiology. Tools to perform virtual surgery, and predict flow dynamic and circulatory results, have been developed for some of the most complex defects, such as those requiring single ventricle palliation. In today's quest for personalized medicine and precision care, computational modeling's role to assist surgical planning in complex congenital heart surgery will continue to grow and evolve. With ever closer collaboration between surgeons and engineers, and clear understanding of modeling limitations, computational simulations can be a valuable adjunct to support preoperative surgical decision making.

Pulmonary Vasodilator Therapy in Children with Single Ventricle Physiology: Effects on Saturation and Pulmonary Arterial Pressure

In children with single ventricle physiology, increased pulmonary vascular resistance may impede surgical progression or result in failing single ventricle physiology. The use of pulmonary vasodilators has been suggested as a potential therapy. However, knowledge on indication, dosage, and effect is limited. A retrospective case notes review of all (n = 36) children with single ventricle physiology, treated with pulmonary vasodilators by the UK Pulmonary Hypertension Service for Children 2004-2017. Therapy was initiated in Stage 1 (n = 12), Glenn (n = 8), or TCPC (n = 16). Treatment indications were high mean pulmonary arterial pressure, cyanosis, reduced exercise tolerance, protein-losing enteropathy, ascites, or plastic bronchitis. Average dose of sildenafil was 2.0 mg/kg/day and bosentan was 3.3 mg/kg/day. 56% had combination therapy. Therapy was associated with a reduction of the mean pulmonary arterial pressure from 19 to 14 mmHg (n = 17, p < 0.01). Initial therapy with one or two vasodilators was associated with an increase in the mean saturation from 80 to 85%, (n = 16, p < 0.01). Adding a second vasodilator did not give significant additional effect. 5 of 12 patients progressed from Stage 1 to Glenn, Kawashima, or TCPC, and 2 of 8 from Glenn to TCPC during a mean follow-up time of 4.7 years (0-12.8). Bosentan was discontinued in 57% and sildenafil in 14% of treated patients and saturations remained stable. Pulmonary vasodilator therapy was well tolerated and associated with improvements in saturation and mean pulmonary arterial pressure in children with single ventricle physiology. It appears safe to discontinue when no clear benefit is observed.

Valve Replacement in Children with Single Ventricle Physiology

Severe atrioventricular valve (AVV) or semilunar valve (SLV) regurgitation in the setting of a single ventricle physiology may proceed to valve replacement if repair strategies fail. Outcome data for these children are limited. We present transplant-free survival of a case series of children with single ventricle physiology undergoing either atrioventricular replacement (AVVR) or semilunar valve replacement (SLVR) from a multi-institutional, US-based registry (Pediatric Cardiac Care Consortium-PCCC). Outcomes were derived from PCCC and by linkage with the National Death Index (NDI) and Organ Procurement Transplant Network (OPTN). Fifty children with single ventricle physiology were identified to have received either AVVR (n = 38) or SLVR (n = 12). There were 17 in-hospital deaths including 8 intraoperative deaths (all intraoperative deaths were among children requiring AVVR). The in-hospital mortality was 42% and 8% for AVVR and SLVR, respectively. Among the 33 children surviving to hospital discharge, follow-up was available in 15 (46%). Death or cardiac transplant after hospital discharge occurred in 10-death in 4 (all among those requiring AVVR), cardiac transplant in 6 (2 following AVVR, 4 following SLVR). Valve replacement in children with single ventricle physiology, especially AVVR, is associated with poor outcomes. Alternative palliation strategies should be considered in children with single ventricle physiology with significant AVV or SLV regurgitations.

Toddler Neurodevelopmental Outcomes Are Associated With School-Age IQ in Children With Single Ventricle Physiology

To examine whether neurodevelopment at preschool age predicts IQ levels and needs for special education services in school-age children with single ventricle (SV) physiology. Thirty-five patients with SV physiology were assessed using the Bayley Scale of Infant and Toddler Development (BSID) II or III at 3 years and the Wechsler Intelligence Scale for Children-Fourth Edition (WISC) at 8 years. Whether the children were receiving special education services was also determined. Factors associated with the mental developmental index (MDI) of the BSID, the full-scale IQ (FSIQ) of the WISC, and special education services were also analyzed. The MDI and FSIQ of children with SV physiology were significantly lower than the values in healthy children (P < 0.01). The MDI at 3 years was moderately correlated with FSIQ at 8 years (P < 0.01, R² = 0.41). Ten patients (28.6%) received special education services in their school. Children with MDI <85 were more likely than those with MDI ≥85 to require special education services at school age (53% and 10%, respectively, P < 0.01). Weight at birth and stage II were correlated with the MDI, extracorporeal circulation time at stage II was correlated with FSIQ, and age at Fontan operation was correlated with FSIQ and special education services. The toddler neurodevelopment index may predict not only IQ levels but also the need for special education services in school-age children. Children with low neurodevelopmental scores need to be followed closely for a long time.

Hemoglobin Level at Stage 1 Discharge has No Impact on Inter-stage Growth and Stability in Single Ventricle Infants

Hemoglobin levels (Hgb) of infants with a single ventricle (SV) are traditionally maintained high to maximize oxygen-carrying capacity during stage 1 palliation (S1P), stage 2 palliation (S2P), and between stages (IS). A single-center observational cohort study was performed to determine if red blood cell transfusion during the convalescent phase of the S1P (late S1P transfusion) to achieve higher Hgb is associated with benefits during the IS including improved growth and decreased acute medical events. 137 infants <1 year with SV with SIP undergoing care from January 2008 to June 2015 were retrospectively evaluated. 78 (57%) infants received a late S1P transfusion. Median Hgb at S1P discharge was 15.9 g/dL (IQR 14.7-17.1) and median Hgb S2P at admission was 15.3 g/dL (IQR 14-16.3). Median daily weight gain was 22 g/day during IS (IQR 17-26) and median daily length gain was 0.09 cm (IQR 0.06-0.11). Hgb at SIP discharge was not associated with IS growth or fewer IS acute events. However, late S1P transfusions were associated with illness severity at S1P and more complicated S1P care. Our data suggest that SV infants after S1P, who are steadily recovering, do not benefit from late transfusion to raise their hemoglobin level at discharge.

The Lymphatic Circulation in Adaptations to the Fontan Circulation

Failing Fontan continues to be major problem for patients on the univentricular pathway. Failing Fontan is often complicated by chylothorax, plastic bronchitis and protein loosing enteropathy. The role of lymphatic circulation in Fontan circulation is still being researched. Newer imaging modalities give insight into the role of abnormal dilatation and retrograde flow in lymphatic channels post Fontan. Interventional strategies targeting abnormal lymphatic channels, provides an alternative management strategy for patients with failing Fontan. This review focuses on the role of lymphatic system in adaptations to Fontan circulation.

Post-cardiotomy Rescue Extracorporeal Cardiopulmonary Resuscitation in Neonates with Single Ventricle After Intractable Cardiac Arrest: Attrition After Hospital Discharge and Predictors of Outcome

Extracorporeal cardiopulmonary resuscitation (ECPR) in children with cardiac arrest refractory to conventional cardiopulmonary resuscitation (CPR) has been reported with encouraging results. We reviewed outcomes of neonates with functional single ventricle (FSV) surviving post-cardiotomy ECPR after hospital discharge. Fifty-eight patients who required post-cardiotomy extracorporeal membrane oxygenation (ECMO) since the introduction of our ECPR protocol (January 2007-December 2011) were identified. Forty-one were neonates. Survival analysis was conducted. Of 41 neonates receiving post-cardiotomy ECMO, 32 had FSV. Twenty-one had ECPR. Fourteen underwent Norwood operation (NO) for hypoplastic left heart syndrome (HLHS). Seven had non-HLHS FSV. Four (of 7) underwent modified NO/DKS with systemic-to-pulmonary shunt (SPS), 2 SPS only and 1 SPS with anomalous pulmonary venous connection repair. Mean age was 6.8 ± 2.1 days. ECMO median duration was 7 days [interquartile range (IQR_25-75: 4-18)]. Survival to ECMO discontinuation was 72% (15 of 21 patients) and at hospital discharge 62% (13 of 21 patients). The most common cause of late attrition was cardiac. At last follow-up (median: 22 months; IQR_25-75: 3-36), 47% of patients were alive. Duration of ECMO and failure of lactate clearance within 24 h from ECMO deployment determined late survival after hospital discharge (p < 0.05). Rescue post-cardiotomy ECMO support in neonates with FSV carries significant late attrition. ECMO duration and failure in lactate clearance after deployment are associated with unfavorable outcome. Emphasis on CPR quality, refinement of management directives early during ECMO and aggressive early identification of patients requiring heart transplantation might improve late survival.

Optimal Timing of Pulmonary Banding for Newborns with Single Ventricle Physiology and Unrestricted Pulmonary Blood Flow

The aim of this study was to determine the optimal timing of pulmonary artery band (PAB) placement in neonates with single ventricle physiology, unrestricted pulmonary blood flow, and no systemic outflow tract obstruction. Retrospective chart review of all patients who underwent isolated PAB for single ventricle physiology between January 2005 and December 2014 was carried out. The influence of age at the time of PAB on operative mortality, the need for reoperation to adjust the PAB, the preparedness of the pulmonary vascular bed prior to the second-stage bidirectional cavopulmonary shunt (BCPS), and the outcomes following BCPS were studied. The study cohort included 54 subjects (34 males). The median age at the time of PAB was 18 days. The overall mortality following PAB was 4 % (2/54). Reoperation for PAB adjustment was 7 % (4/54). Younger age at the time of PAB was not associated with mortality or increased risk of reoperation. There was a mild positive correlation between the age at PAB and the mean pulmonary artery pressure prior to BCPS. There was also a weak positive correlation between the age at PAB and the duration of ventilation following BCPS. Age at the time of PAB did not influence pulmonary vascular resistance (PVR) prior to BCPS or the mortality and hospital stay following BCPS. PAB can be done safely and effectively soon after birth in neonates with single ventricle physiology, increased pulmonary blood flow, and no potential or actual systemic outflow tract obstruction. It may not be necessary to wait for a few weeks after birth for the neonatal PVR to fall before placing a PAB.

Long term negative pressure ventilation: Rescue for the failing fontan?

Current treatment strategies for single ventricle patients include non-intervention strategy, surgical palliation or primary transplantation. Surgical palliation includes a staged operative course culminating in the Fontan operation. With progress in surgical techniques, the survival has been improving. However, almost all of these Fontan patients will demonstrate pathophysiologic changes that ultimately constitute “Fontan failure physiology”. This article reviews the pathophysiologic changes, current approach to management of these patients and proposes a novel way of reversing some of the pathophysiologic changes by utilization of negative pressure ventilation.