Pulmonary arteriovenous malformations after the superior cavopulmonary shunt: mechanisms and clinical implications

Impact of Age-Related Change in Caval Flow Ratio on Hepatic Flow Distribution in the Fontan Circulation

BACKGROUND

The Fontan operation is a palliative technique for patients born with single ventricle heart disease. The superior vena cava (SVC), inferior vena cava (IVC), and hepatic veins are connected to the pulmonary arteries in a total cavopulmonary connection by an extracardiac conduit or a lateral tunnel connection. A balanced hepatic flow distribution (HFD) to both lungs is essential to prevent pulmonary arteriovenous malformations and cyanosis. HFD is highly dependent on the local hemodynamics. The effect of age-related changes in caval inflows on HFD was evaluated using cardiac magnetic resonance data and patient-specific computational fluid dynamics modeling.

METHODS

SVC and IVC flow from 414 patients with Fontan were collected to establish a relationship between SVC:IVC flow ratio and age. Computational fluid dynamics modeling was performed in 60 (30 extracardiac and 30 lateral tunnel) patient models to quantify the HFD that corresponded to patient ages of 3, 8, and 15 years, respectively.

RESULTS

SVC:IVC flow ratio inverted at ≈8 years of age, indicating a clear shift to lower body flow predominance. Our data showed that variation of HFD in response to age-related changes in caval inflows (SVC:IVC, 2, 1, and 0.5 corresponded to ages, 3, 8, and 15+, respectively) was not significant for extracardiac but statistically significant for lateral tunnel cohorts. For all 3 caval inflow ratios, a positive correlation existed between the IVC flow distribution to both the lungs and the HFD. However, as the SVC:IVC ratio changed from 2 to 0.5 (age, 3-15+) years, the correlation's strength decreased from 0.87 to 0.64, due to potential flow perturbation as IVC flow momentum increased.

CONCLUSIONS

Our analysis provided quantitative insights into the impact of the changing caval inflows on Fontan's long-term HFD, highlighting the importance of SVC:IVC variations over time on Fontan's long-term hemodynamics. These findings broaden our understanding of Fontan hemodynamics and patient outcomes.

Impact of Age-related change in Caval Flow Ratio on Hepatic Flow Distribution in Fontan

Background

The Fontan operation is a palliative technique for patients born with single ventricle heart disease. The superior vena cava (SVC), inferior vena cava (IVC), and hepatic veins are connected to the pulmonary arteries in a total cavopulmonary connection by an extracardiac (EC) conduit or a lateral tunnel (LT) connection. A balanced hepatic flow distribution (HFD) to both lungs is essential to prevent pulmonary arteriovenous malformations and cyanosis. HFD is highly dependent on the local hemodynamics.

Objective

The effect of age-related changes in caval inflows on HFD was evaluated using cardiac MRI (CMR) data and patient-specific computational fluid dynamics (CFD) modeling.

Methods

SVC and IVC flow from 414 Fontan patients were collected to establish a relationship between SVC:IVC flow ratio and age. CFD modeling was performed in 60 (30 EC and 30 LT) patient models to quantify the HFD that corresponded to patient ages of 3, 8, and 15 years, respectively.

Results

SVC:IVC flow ratio inverted at ∼8 years of age, indicating a clear shift to lower body flow predominance. Our data showed that variation of HFD in response to age-related changes in caval inflows (SVC:IVC = 2,1, and 0.5 corresponded to ages 3, 8, and 15+ respectively) was not significant for EC but statistically significant for LT cohorts. For all three caval inflow ratios, a positive correlation existed between the IVC flow distribution to both the lungs and the HFD. However, as the SVC:IVC ratio changed from 2→0.5 (age 3→15+), the correlation's strength decreased from 0.87→0.64, due to potential flow perturbation as IVC flow momentum increased.

Conclusion

Our analysis provided quantitative insights into the impact of the changing caval inflows on Fontan's long-term HFD, highlighting the importance of including SVC:IVC variations over time to understand Fontan's long-term hemodynamics. These findings broaden our understanding of Fontan hemodynamics and patient outcomes.

Clinical Perspective

With improvement in standard of care and management of single ventricle patients with Fontan physiology, the population of adults with Fontan circulation is increasing. Consequently, there is a clinical need to comprehend the impact of patient growth on Fontan hemodynamics. Using CMR data, we were able to quantify the relationship between changing caval inflows and somatic growth. We then used patient-specific computational flow modeling to quantify how this relationship affected the distribution of long-term hepatic flow in extracardiac and lateral tunnel Fontan types. Our findings demonstrated the significance of including SVC:IVC changes over time in CFD modeling to learn more about the long-term hemodynamics of Fontan. Fontan surgical approaches are increasingly planned and optimized using computational flow modeling. For a patient undergoing a Fontan procedure, the workflow presented in this study that takes into account the variations in Caval inflows over time can aid in predicting the long-term hemodynamics in a planned Fontan pathway.

Collaterals in congenital heart disease: when and how to treat?

The development of collateral circulation is not that rare in patients with congenital heart defects. These collaterals can affect cardiovascular hemodynamics and cause systemic arterial desaturation, which arises the question whether these should be closed. To date, few if any reports have been published on the therapeutic management of collaterals in adult patients with congenital heart disease in heart failure (HF). The focus of this article is to provide a pragmatic approach in the assessment of collateral circulation of the patient with HF. By considering the underlying hemodynamics and overall effects of the collateral circulation, we aim to provide a practical tool useful in clinical decision making. The paper highlights mainly the systemic venous to systemic venous collaterals, systemic venous to pulmonary venous (or pulmonary venous atrium) collaterals, and pulmonary arterio-venous malformations. Systemic venous anomalies are frequent and reported in 20% to 40% of patients who underwent Glenn or Fontan procedure. A reduction in effective pulmonary blood flow, coupled with increasing oxygen demands with growth, as well as a pressure difference between the higher pressure caval venous system and lower pressure atria (so called decompressing collaterals) are potential causes of collateral formation. Whether angiogenesis de novo or reappearance of embryological venous channels is responsible for collateral formation remains to be elucidated.

Virtual treatment planning in three patients with univentricular physiology using computational fluid dynamics—Pitfalls and strategies

Background

Uneven hepatic venous blood flow distribution (HFD) to the pulmonary arteries is hypothesized to be responsible for the development of intrapulmonary arteriovenous malformations (PAVM) in patients with univentricular physiology. Thus, achieving uniform distribution of hepatic blood flow is considered favorable. However, no established method for the prediction of the post-interventional hemodynamics currently exists. Computational fluid dynamics (CFD) offers the possibility to quantify HFD in patient-specific anatomies before and after virtual treatment. In this study, we evaluated the potential benefit of CFD-assisted treatment planning.

Materials and methods

Three patients with total cavopulmonary connection (TCPC) and PAVM underwent cardiovascular magnetic resonance imaging (CMR) and computed tomography imaging (CT). Based on this imaging data, the patient-specific anatomy was reconstructed. These patients were considered for surgery or catheter-based intervention aiming at hepatic blood flow re-routing. CFD simulations were then performed for the untreated state as well as for different surgical and interventional treatment options. These treatment options were applied as suggested by treating cardiologists and congenital heart surgeons with longstanding experience in interventional and surgical treatment of patients with univentricular physiology. HFD was quantified for all simulations to identify the most viable treatment decision regarding redistribution of hepatic blood flow.

Results

For all three patients, the complex TCPC anatomy could be reconstructed. However, due to the presence of metallic stent implants, hybrid models generated from CT as well as CMR data were required. Numerical simulation of pre-interventional HFD agreed well with angiographic assessment and physiologic considerations. One treatment option resulting in improvement of HFD was identified for each patient. In one patient follow-up data after treatment was available. Here, the virtual treatment simulation and the CMR flow measurements differed by 15%.

Conclusion

The combination of modern computational methods as well as imaging methods for assessment of patient-specific anatomy and flow might allow to optimize patient-specific therapy planning in patients with pronounced hepatic flow mismatch and PAVM. In this study, we demonstrate that these methods can also be applied in patients with complex univentricular physiology and extensive prior interventions. However, in those cases, hybrid approaches utilizing information of different image modalities may be required.

Pulmonary Arteriovenous Fistulae After Fontan Operation: Incidence, Clinical Characteristics, and Impact on All-Cause Mortality

BACKGROUND

The Fontan operation is a surgical procedure used in children with univentricular hearts. Pulmonary arteriovenous fistulae (PAVF) is a major complication after a Fontan operation. However, the incidence and related clinical pathophysiology of PAVF remain unclear.

PURPOSE

This study aimed to clarify the incidence of PAVF, its clinical characteristics, and its influence on all-cause mortality.

METHODS AND RESULTS

We serially assessed the presence of PAVF using pulmonary artery angiography and/or contrast echocardiography during catheterization in 391 consecutive patients who underwent the Fontan procedure and compared the results with the Fontan pathophysiology and all-cause mortality. PAVF developed in 36 patients (9.2%), including 30 diffuse- and six discrete-PAVF types. The PAVF-free rates at 1, 5, 10, 15, 20, and ≥25 years after Fontan operation were 97, 96, 93, 88, 87, and 83%, respectively. The mean arterial blood oxygen saturation (SaO₂) in patients with diffuse PAVF at each corresponding postoperative stage were 90, 91, 91, 91, 89, and 88%, respectively, indicating lower SaO₂ levels than those in patients without PAVF (all p < 0.01). However, there was no difference in the SaO₂ levels between patients with discrete PAVF and those without PAVF. During a median follow-up period of 2.9 years after the last catheterization, 31 patients, including 12 patients with PAVF, died. Patients with PAVF, especially those with diffuse PAVF, had a higher mortality rate (p = 0.01) than those without PAVF (hazard ratio: 3.6, 95% confidence interval: 1.6-7.8, p = 0.0026).

CONCLUSION

Patients who underwent Fontan surgery had an increased incidence of PAVF as they aged. Discrete PAVF did not influence SaO₂ or mortality, whereas the presence of diffuse PAVF caused hypoxia and was associated with all-cause mortality.

Liver abnormalities in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a cardiopulmonary disease with high mortality. In recent years, it has been recognized that PAH is a multi-organ system disease, involving the systemic circulation, kidneys, skeletal muscles, and the central nervous system, among others. Right heart failure produces congestive hepatopathy, a disease state that has direct consequences on liver biochemistry, histology, and systemic glucose and lipid metabolism. This article aims to summarize the consequences of congestive hepatopathy with an emphasis on liver biochemistry, histology, and PAH-targeted therapy. Furthermore, PAH-specific changes in glucose and lipid metabolism will be discussed.

The Influence of Respiration on Blood Flow in the Fontan Circulation: Insights for Imaging-Based Clinical Evaluation of the Total Cavopulmonary Connection

Congenital heart disease is the most common birth defect and functionally univentricular heart defects represent the most severe end of this spectrum. The Fontan circulation provides an unique solution for single ventricle patients, by connecting both caval veins directly to the pulmonary arteries. As a result, the pulmonary circulation in Fontan palliated patients is characterized by a passive, low-energy circulation that depends on increased systemic venous pressure to drive blood toward the lungs. The absence of a subpulmonary ventricle led to the widely believed concept that respiration, by sucking blood to the pulmonary circulation during inspiration, is of great importance as a driving force for antegrade blood flow in Fontan patients. However, recent studies show that respiration influences pulsatility, but has a limited effect on net forward flow in the Fontan circulation. Importantly, since MRI examination is recommended every 2 years in Fontan patients, clinicians should be aware that most conventional MRI flow sequences do not capture the pulsatility of the blood flow as a result of the respiration. In this review, the unique flow dynamics influenced by the cardiac and respiratory cycle at multiple locations within the Fontan circulation is discussed. The impact of (not) incorporating respiration in different MRI flow sequences on the interpretation of clinical flow parameters will be covered. Finally, the influence of incorporating respiration in advanced computational fluid dynamic modeling will be outlined.

A Cavopulmonary Assist Device for Long-Term Therapy of Fontan Patients

Treatment of univentricular hearts remains restricted to palliative surgical corrections (Fontan pathway). The established Fontan circulation lacks a subpulmonary pressure source and is commonly accompanied by progressively declining hemodynamics. A novel cavopulmonary assist device (CPAD) may hold the potential for improved therapeutic management of Fontan patients by chronic restoration of biventricular equivalency. This study aimed at translating clinical objectives toward a functional CPAD with preclinical proof regarding hydraulic performance, hemocompatibility and electric power consumption. A prototype composed of hemocompatible titanium components, ceramic bearings, electric motors, and corresponding drive unit was manufactured for preclinical benchtop analysis: hydraulic performance in general and hemocompatibility characteristics in particular were analyzed in-silico (computational fluid dynamics) and validated in-vitro. The CPAD's power consumption was recorded across the entire operational range. The CPAD delivered pressure step-ups across a comprehensive operational range (0-10 L/min, 0-50 mm Hg) with electric power consumption below 1.5 W within the main operating range. In-vitro hemolysis experiments (N = 3) indicated a normalized index of hemolysis of 3.8 ± 1.6 mg/100 L during design point operation (2500 rpm, 4 L/min). Preclinical investigations revealed the CPAD's potential for low traumatic and thrombogenic support of a heterogeneous Fontan population (pediatric and adult) with potentially accompanying secondary disorders (e.g., elevated pulmonary vascular resistance or systemic ventricular insufficiency) at distinct physical activities. The low power consumption implied adequate settings for a small, fully implantable system with transcutaneous energy transfer. The successful preclinical proof provides the rationale for acute and chronic in-vivo trials aiming at the confirmation of laboratory findings and verification of hemodynamic benefit.

Diagnosis and endovascular management of pulmonary arteriovenous malformations

Pulmonary arteriovenous malformations (PAVM) are abnormal communication of a branch of the pulmonary artery and pulmonary vein circumventing the intervening pulmonary capillaries. This results in a right-to-left (R-L) shunt and its related manifestations, which include hampered gas exchange leading to hypoxaemia, dyspnoea, paradoxical emboli leading to stroke, cerebral abscess, myocardial infarction and pulmonary haemorrhage due to rupture of the PAVM. Endovascular transcatheter embolization of the feeding vessels with coils or occlusion devices is the current standard care of treatment and preferred treatment modality. The articles aim to provide insights into the current trends in diagnosis, the current recommendations, approach and management options for patients with PAVM.

Non-uniform mixing of hepatic venous flow and inferior vena cava flow in the Fontan conduit

Fontan patients require a balanced hepatic blood flow distribution (HFD) to prevent pulmonary arteriovenous malformations. Currently, HFD is quantified by tracking Fontan conduit flow, assuming hepatic venous (HV) flow to be uniformly distributed within the Fontan conduit. However, this assumption may be unvalid leading to inaccuracies in HFD quantification with potential clinical impact. The aim of this study was to (i) assess the mixing of HV flow and inferior vena caval (IVC) flow within the Fontan conduit and (ii) quantify HFD by directly tracking HV flow and quantitatively comparing results with the conventional approach. Patient-specific, time-resolved computational fluid dynamic models of 15 total cavopulmonary connections were generated, including the HV and subhepatic IVC. Mixing of HV and IVC flow, on a scale between 0 (no mixing) and 1 (perfect mixing), was assessed at the caudal and cranial Fontan conduit. HFD was quantified by tracking particles from the caudal (HFD_{caudal conduit}) and cranial (HFD_{cranial conduit}) conduit and from the hepatic veins (HFD_HV). HV flow was non-uniformly distributed at both the caudal (mean mixing 0.66 ± 0.13) and cranial (mean 0.79 ± 0.11) level within the Fontan conduit. On a cohort level, differences in HFD between methods were significant but small; HFD_HV (51.0 ± 20.6%) versus HFD_{caudal conduit} (48.2 ± 21.9%, p = 0.033) or HFD_{cranial conduit} (48.0 ± 21.9%, p = 0.044). However, individual absolute differences of 8.2–14.9% in HFD were observed in 4/15 patients. HV flow is non-uniformly distributed within the Fontan conduit. Substantial individual inaccuracies in HFD quantification were observed in a subset of patients with potential clinical impact.

Hepatopulmonary Syndrome and Multiple Arteriovenous Fistulas in a Child with Niemann-Pick Disease

Background: Niemann-Pick disease (NPD) is caused by abnormal storage of sphingomyelin. NPD may affect the pulmonary system and cause hypoxia. In the present case, both hepatopulmonary syndrome (HPS) and pulmonary arteriovenous fistulas (PAVFs) developed in a child with NPD and were successfully treated with repeated embolization. Case Presentation: We have reported the case of a 16-year-old-girl with NPD who suffered severe hypoxia, dyspnea, fatigue, had multiple PAVFs, and was diagnosed with type 2 HPS. To improve oxygenation, 10 PAVFs were embolized. She needed re-embolization after 9 months because of hypoxia redevelopment. Conclusions: Pulmonary involvement, HPS, and/or PAVFs could be responsible for hypoxemia in patients with NPD, who should, therefore, be investigated for HPS and PAVFs. Embolization could be beneficial. Some patients may need repeated embolization.

The Glenn procedure: Clinical outcomes in patients with congenital heart disease in pakistan

Objectives:

Congenital heart defects (CHDs) affect more than 40,000 children annually in Pakistan. Approximately 80% of patients require at least one surgical intervention to achieve a complete or palliative cardiac repair. The Glenn shunt, a palliative procedure is established between superior vena cava (SVC) and the right pulmonary artery to provide an anastomosis offering minimal risk to patients with univentricular heart disease. The aim of this study was to assess the clinical outcomes of the Glenn shunt procedure in patients with complex congenital heart diseases in a developing country like Pakistan.

Materials and Methods:

A retrospective chart review was conducted on patients who underwent a bidirectional Glenn shunt procedure from July 2006 to June 2017. Data were collected on a structured questionnaire and analyses performed on SPSS version 22. Frequencies and percentages were computed for categorical variables while mean and standard deviation for continuous variables where appropriate.

Results:

A total of 79 patients underwent the Glenn shunt procedures. The median age was 1.9 years and 54.5% were male. Tricuspid atresia was the primary diagnosis in 30.4% of the patients. Common morbidities included arrhythmias (6.3%), pleural effusion (8.9%), wound infection (3.8%), pneumonia (2.5%), and seizures (3.8%); reopening was required in 2.5% of the patients and 8.8% were readmitted within 30 days of index operation. There were three (3.8%) deaths in total.

Conclusions:

Bidirectional Glenn shunt procedure can be performed safely in patients with ideal characteristics as the first stage palliation and has favorable results with acceptable rate of complications.

Asking Bubbles for Direction: Assessment of a Classic Glenn Shunt Using Agitated Saline Contrast Echocardiography

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Glenn shunt is a common palliative surgery for congenital heart disease.

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PAVMs are a frequent complication.

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A saline contrast study can show bubbles first appearing in the left atrium.

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Treatment options include coil embolization and surgery.

Pulmonary arteriovenous malformations in children after the Kawashima procedure: Risk factors and midterm outcome

Background:

Pulmonary arteriovenous malformations (PAVMs) are the major cause of progressive cyanosis in patients palliated with bidirectional cavopulmonary connection (BCPC). The aim of our study is to analyze the occurrence of PAVMs in patients after Kawashima procedure, to study the effect of total cavopulmonary connection (TCPC) on PAVMs, to evaluate the effect of axillary arteriovenous fistula (AAVF) creation on PAVMs, and to study the risk factors for PAVMs.

Methods:

In this retrospective cohort study, all patients with left isomerism and azygous continuation of an interrupted inferior vena cava who underwent Kawashima procedure from July 2001 to December 2017 were included.

Results:

Twenty.six patients after Kawashima procedure were included in our study. PAVMs were diagnosed in 12 patients (46%). Five of these 12 patients underwent TCPC with complete resolution of hypoxemia. Three patients underwent AAVF creation, 2 had complete resolution, while 1 had partial resolution of hypoxemia. Fourteen patients (54%) did not develop PAVMs. Nakata index below 267 mm²/m²and McGoon ratio below 1.9 predicted the development of PAVMs with high sensitivity and specificity.

Conclusions:

PAVMs represent a serious complication in patients who undergo Kawashima procedure. Small size of pulmonary arteries is an important risk factor for the development of PAVMs. Resolution of hypoxemia after TCPC completion supports the hepatic factor hypothesis. Early TCPC completion in these patients may help to avoid the development of PAVMs by restoring the hepatic factor. Resolution of hypoxemia after AAVF creation may support the lack of pulsatile flow hypothesis.

Hepatic to azygos connection by autologous pericardial roll for Fontan completion

Techniques for performing the Fontan completion procedure after Kawashima procedure have developed in recent years. This paper presents a case in which we performed an off-pump hepatic-to-azygos connection by autologous pericardial roll via thoracotomy as a modified Fontan completion. The operation wound was limited, and the short-term follow-up was satisfactory. Notably, it was found that the autologous pericardium might require a shorter period of anticoagulation treatment than what is needed for artificial prosthetic materials.

Superior Cavopulmonary Connection: Its Physiology, Limitations, and Anesthetic Implications

The superior cavopulmonary connection (SCPC) or "bidirectional Glenn" is an integral, intermediate stage in palliation of single ventricle patients to the Fontan procedure. The procedure, normally performed at 3 to 6 months of life, increases effective pulmonary blood flow and reduces the ventricular volume load in patients with single ventricle (parallel circulation) physiology. While the SCPC, with or without additional sources of pulmonary blood flow, cannot be considered a long-term palliation strategy, there are a subset of patients who require SCPC palliation for a longer interval than the typical patient. In this article, we will review the physiology of SCPC, the consequences of prolonged SCPC palliation, and modes of failure. We will also discuss strategies to augment pulmonary blood flow in the presence of an SCPC. The anesthetic considerations in SCPC patients will also be discussed, as these patients may present for noncardiac surgery from infancy to adulthood.

Conversion of prior univentricular repairs to septated circulation: Case selection, challenges, and outcomes

Objectives

Complex congenital heart defects that present earlier in life are sometimes channelled in the single ventricle pathway, because of anatomical or logistic challenges involved in biventricular correction. Given the long-term functional and survival advantage, and with the surgeons' improved understanding of the cardiac anatomy, we have consciously explored the feasibility of a biventricular repair in these patients when they presented later for Fontan completion. We present a single institution's 10-year experience in achieving biventricular septation of prior univentricular repairs, the technical and physiological challenges and the surgical outcomes.

Methods

Between June 2010 and December 2019, 246 patients were channelized in the single ventricle pathway, of which 32 patients were identified as potential biventricular candidates at the time of evaluation for Fontan palliation, considering their anatomic feasibility. The surgical technique involves routing of the left ventricle to the aorta across the ventricular septal defect, ensuring an adequate sized right ventricular cavity, establishing right ventricle-pulmonary artery continuity and taking down the Glenn shunt with rerouting of the superior vena cava to the right atrium. This is a retrospective study where we reviewed the unique physiological and surgical characteristics of this subset of patients and analysed their surgical outcomes and complications.

Results

Biventricular conversion was achieved in all cases except in 3 patients, who had the Glenn shunt retained leading to a one and a half ventricle repair. The average age of the patients was 4.9 years of whom 18 were male. The average cardiopulmonary bypass time was 371 min with an average cross clamp time of 162 min. There was one mortality in a patient with corrected transposition of great arteries (c-TGA) with extensive arterio-venous malformations (AVMs). At a median follow-up of 60 months, all patients remained symptom free except two with NYHA II symptoms, one being treated for branch pulmonary artery stenosis with balloon dilatation and the other with multiple AVMs who needed coil closure. One patient with branch pulmonary artery (PA) stenosis required balloon dilatation and stent placement.

Conclusion

The possibility of achieving the surgical goal in this unique subset of patients evolves with the progressive experience of the congenital heart surgeon. Case selection is a crucial aspect in achieving the desired outcome, and this 'borderline' substrate is often recognized at the time of evaluation for the Fontan completion. A comprehensive preoperative imaging and planning helps in achieving the surgical septation and reconnection to achieve the desired physiological circulation. Though technically challenging, the surgery has excellent short- and mid-term outcomes as evidenced by our 10-year experience.

Usefulness of 4D-Flow MRI in Mapping Flow Distribution Through Failing Fontan Circulation Prior to Cardiac Intervention

We report a case of a 23-year-old male with failing Fontan circulation who was taken to the catheterization lab to better evaluate the Fontan circulation and hemodynamics. Catheterization revealed arteriovenous malformations exclusively present in the right lung leading to the consideration of placing stents to direct the inferior vena cava flow through the Fontan circuit to the right pulmonary artery (RPA), thus increasing the RPA concentration of the hepatic factor. However, comprehensive 4D-Flow MRI analyses indicated sufficient distribution of the hepatic flow between branch pulmonary arteries, and consequently no further invasive intervention to redirect hepatic flow was performed.

Glenn Procedure in a Baby with Single Pulmonary Artery and Single Lung

Glenn followed by Fontan are still the main two procedures for the treatment of patients with single ventricle. Some patients may be challenging due to unfavorable cardiopulmonary anatomy. In this report, we present Glenn shunt procedure in a patient with single pulmonary artery and congenitally agenetic lung.

Impact of Time Interval Between Glenn and Fontan Procedures on Fontan Operative and Long-Term Follow-up Results

OBJECTIVE

The bidirectional cavopulmonary shunt (BCPS) is an effective palliative procedure which has been widely used to boost outcome of the Fontan procedure. However, there is no standard duration time between these two procedures. Therefore, we investigated whether different time intervals between BCPS and Fontan procedure affects morbidity and mortality of Fontan patients.

METHODS

Between 2004 and 2016, 210 post-BCPS patients underwent Fontan operation at Fuwai Hospital. The median interval between BCPS and Fontan procedure was 3.7 years (range 0.55-11.86 years) and this was used to divide study cohort into Group 1 (< 3.7 years; n = 124) and Group 2 (> 3.7 years; n = 86). We analyzed these patients retrospectively in terms of their preoperative characteristics and post-operative and follow-up results.

RESULTS

Weight z-scores for age at BCPS (- 0.73 ± 1.39 vs - 1.17 ± 1.60, p < 0.05) was significantly higher in Group 2. However, saturation at room air before Fontan (76.42 ± 20.01 vs 82.85 ± 9.69, p < 0.001) was significantly higher in Group 1. The morbidity and mortality were similar between two groups. There were twelve hospital deaths (5.7%): eight (8/124, 6.5%) presented in Group 1 and four (4/86, 4.7%) in Group 2. On multi-variable analysis, risk factors for death were prolonged mechanical ventilation [hazard ratio (HR) 1.02, p = 0.004] and single right ventricle (HR 7.17, p = 0.03). After a mean follow-up of 4.95 years (range 0.74-13.62 years), one patient in Group 1 died of heart failure 13 months after Fontan procedure. The overall Fontan failure in Group 1 was similar to that in Group 2 (2.7% vs 2.6%, p = 0.985). The incidence of arrhythmias and re-intervention were not different between the two groups.

CONCLUSIONS

Fontan procedure could be performed safely in patient who stayed in long duration between Fontan procedure and BCPS without affecting the operative and long-term follow-up results. However, for post-BCPS patients with severe hypoxemia, earlier age at Fontan might be a good choice.

Successful use of calcium channel blocker for management of arterio-venous malformations following Fontan procedure

In diffuse forms of arteriovenous malformation following Fontan procedure, "classical" medical therapy, inhaled nitric oxide and sildenafil, may play a role, until re-direction of hepatic flow to pulmonary circulation cures it. However, in refractory cases, as reported in our 2-year-old patient, unusual medications such as calcium channel blockers can be tried and continued if patients respond adequately.

Pulsatile Glenn as long-term palliation for single ventricle physiology patients

OBJECTIVE

There are limited studies analyzing pulsatile Glenn as a long-term palliation strategy for single ventricle patients. This study sought to determine their outcomes at a single institution.

DESIGN

A retrospective review was performed.

SETTING

Study performed at a single pediatric hospital.

PATIENTS

All single ventricle patients who underwent pulsatile Glenn from 1995 to 2016 were included.

OUTCOME MEASURES

Pulsatile Glenn failure was defined as takedown, transplant, or death. Further palliation was defined as Fontan, 1.5, or biventricular repair. Risk factors were assessed by Cox multivariable competing risk analyses.

RESULTS

Seventy-eight patients underwent pulsatile Glenn at age 9 months (interquartile range, 5-14). In total, 28% had heterotaxy, 18% had a genetic syndrome, and 24% had an abnormal inferior vena cava. There were 3 (4%) perioperative mortalities. Further palliation was performed in 41 (53%) patients with a median time-to-palliation of 4 years (interquartile range, 3-5). Pulsatile Glenn failure occurred in 10 (13%) patients with 8 total mortalities. Five- and 10-year transplant-free survival were 91% and 84%, respectively. At a median follow-up of 6 years (interquartile range, 2-8), 27 patients (35%) remained with PG (age 7 years [interquartile range, 3-11], oxygen saturation 83% ± 4%). Preoperative moderate-severe atrioventricular valve regurgitation (AVVR) (hazard ratio 7.77; 95% confidence interval 1.80-33.43; P =.005) and higher pulmonary vascular resistance (hazard ratio 2.59; 95% confidence interval 1.08-6.15; P =.031) were predictors of pulsatile Glenn failure after adjusting for covariates. Reaching further palliation was less likely in patients with preoperative moderate-severe AVVR (hazard ratio 0.22, 95% confidence interval 0.08-0.59; P =.002).

CONCLUSION

Pulsatile Glenn can be an effective tool to be used in challenging circumstances, these patients can have a favorable long-term prognosis without reducing their suitability for further palliation.

A tale of two cases of pulmonary arteriovenous malformation: How they fared after cardiac transplantation

BACKGROUND

In single ventricle patients, aortopulmonary collaterals (APCs) and pulmonary arteriovenous malformations (PAVMs) following superior cavopulmonary shunt (CPS) can complicate orthotopic heart transplant (OHT) by cyanosis and hemoptysis. Although PAVMs can regress with the restoration of hepatic venous flow to the pulmonary circulation, the effects of hypoxemia on the "unconditioned" allograft are not known.

CASES

Two patients with significant PAVMs after CPS were cyanotic following OHT. One patient with predominantly unilateral left PAVMs had arterial saturation levels less than 70% despite pulmonary vasodilators and ventilation. A custom flow restrictor-covered stent was deployed in the pulmonary artery of the affected side, redirecting the blood flow to the contralateral lung, immediately improving cyanosis. When the PAVMs regressed, the flow restrictor stent was dilated to eliminate the constriction. The second patient with PAVMs had cyanosis and severe hemoptysis from APCs post-OHT. The APCs required an extensive coil embolization, while the cyanosis responded to oxygen and pulmonary vasodilators. Both recipients did well with gradual resolution of PAVMs within 8 months.

CONCLUSIONS

Despite cyanosis from right-to-left intrapulmonary shunting, allograft function recovered. Novel transcatheter interventions can play a role in patients with significant APCs or PAVM following cardiac transplantation.

The Outcomes of Superior Cavopulmonary Connection Operation: a Single Center Experience

Introduction

The superior cavopulmonary connection operation is one of the stages of the palliative surgical management for patients with functionally single ventricle. After surviving this stage, the patients are potential candidates for the final palliative procedure: the Fontan operation.

Objectives

This study aimed to analyze the outcomes of superior cavopulmonary connection operations in our center and to identify factors affecting the survival and the progression to Fontan stage.

Methods

The outcomes of 161 patients were retrospectively analyzed after undergoing superior cavopulmonary connection operation in our center between 2005 and 2015.

Results

The early mortality rate was 2.5%. Five (3.1%) patients underwent takedown of the superior cavopulmonary connection. The rate of exclusion from the Fontan stage was 8.3%. Statistical analysis revealed that elevated mean pulmonary artery pressure preoperatively and the prior palliation with pulmonary artery banding were risk factors for both early mortality and takedown; however, the age, the morphology of the single ventricle and the type of operation were not considered risk factors.

Conclusion

The superior cavopulmonary connection operation can be performed with low rate mortality and morbidity; however, the elevated mean pulmonary artery pressure preoperatively and the prior pulmonary artery banding are associated with poor outcomes.

Bidirectional Inferior Cavopulmonary Anastomosis: Pre-Fontan Interim Palliation

We report a novel method of constructing an extracardiac bidirectional inferior cavopulmonary anastomosis. Our patient was a 4-month-old girl with complex single-ventricle anatomy and a small-caliber superior vena cava. A direct anastomosis from the inferior vena cava to the main pulmonary artery was constructed by using all autologous tissue. The resulting pathway remained patent and exhibited growth with age. Furthermore, a pulmonary arteriovenous malformation did not develop. This case demonstrates how a bidirectional inferior cavopulmonary anastomosis is feasible in the human and can provide similar hemodynamic results as the bidirectional superior cavopulmonary anastomosis.

Development of a Pulmonary Arteriovenous Fistula after a Modified Glenn Shunt in Tetralogy of Fallot and Its Resolution after Shunt Takedown in a 57-Year-Old Patient

Pulmonary arteriovenous fistula (PAVF) is a complication of the Glenn shunt. A 57-year-old tetralogy of Fallot (TOF) patient, who had undergone a Glenn shunt and TOF total correction, complained of dyspnea and cyanosis. PAVFs were present in the right lung, and right lung perfusion was nearly absent. After coil embolization, takedown of the Glenn shunt, and reconstruction of the right pulmonary artery, the patient’s symptoms were relieved. Extrapulmonary radioisotope uptake caused by the PAVFs shown in lung perfusion scans decreased, and right lung perfusion increased gradually. Although the development and resolution of PAVFs after a Glenn shunt have been reported in the pediatric population, this may be the first report on this change in old age.