Echocardiographic evaluation of univentricular physiology and cavopulmonary shunts

Since the surgical palliation of a univentricular congenital heart defect was first described in the early 1970s, thousands of lives were saved by this groundbreaking operation. Although initially described for the palliation of tricuspid valve atresia, the Fontan operation is now utilized for many other univentricular heart defects involving either hypoplastic right or left ventricles, and the number of babies who survive the surgery and the postsurgical hospitalization continues to grow. Echocardiography constitutes the mainstay follow‐up imaging modality for patients with a Fontan system. In order to obtain all the needed information from the echocardiographic studies, close familiarity with the native congenital heart defects, the build of the Fontan systems, and the potential long‐term complications is required. Detailed studies provide valuable information on the various components of the Fontan circulation such as the function of the single ventricle and the valves, flow in the Glenn and Fontan pathways, and possible sources of cyanosis and shunts. Three‐dimensional and transesophageal echocardiogram studies can assist in delineating the Fontan anatomy and to evaluate smaller intracardiac structures.     

Somatic growth failure after the Fontan operation

Our study was designed to characterize the patterns of growth, in the medium term, of children with functionally univentricular hearts managed with a hemi-Fontan procedure in infancy, followed by a modified Fontan operation in early childhood. Failure of growth is common in patients with congenital cardiac malformations, and may be related to congestive heart failure and hypoxia. Repair of simple lesions appears to reverse the retardation in growth. Palliation of the functionally single ventricular physiology with a staged Fontan operation reduces the adverse effects of hypoxemia and prolonged ventricular volume overload. The impact of this approach on somatic growth is unknown. Retrospectively, we reviewed the parameters of growth of all children with functionally univentricular hearts followed primarily at our institution who had completed a staged construction of the Fontan circulation between January 1990 and December 1995. Measurements were available on all children prior to surgery, and annually for three years following the Fontan operation. Data was obtained on siblings and parents for comparative purposes. The criterions of eligibility for inclusion were satisfied by 65 patients. The mean Z score for weight was -1.5 +/- 1.2 at the time of the hemi-Fontan operation. Weight improved by the time of completion of the Fontan circulation (-0.91 +/- 0.99), and for the first two years following the Fontan operation, but never normalized. The mean Z scores for height at the hemi-Fontan and Fontan operations were -0.67 +/- 1.1 and -0.89 +/- 1.2 respectively. At most recent follow-up, with a mean age of 6.1 +/- 1.3 years, and a mean time from the Fontan operation of 4.4 +/- 1.4 years, the mean Z score for height was -1.15 +/- 1.2, and was significantly less than comparable Z scores for parents and siblings. In our experience, children with functionally univentricular hearts who have been palliated with a Fontan operation are significantly underweight and shorter than the general population and their siblings.     

Orthotopic heart transplantation in patients with univentricular physiology

Parallel advancements in surgical technique, preoperative and postoperative care, as well as a better understanding of physiology in patients with duct-dependent pulmonary or systemic circulation and a functional single ventricle, have led to superb results in staged palliation of most complex congenital heart disease (CHD) [1]. The Fontan procedure and its technical modifications have resulted in markedly improved outcomes of patients with single ventricle anatomy [2,3,4]. The improved early survival has led to an exponential increase of the proportion of Fontan patients surviving long into adolescence and young adulthood [5]. Improved early and late survival has not yet abolished late mortality secondary to myocardial failure, therefore increasing the referrals for cardiac transplantation [6]. Interstage attrition [7] is moreover expected in staged palliation towards completion of a Fontan-type circulation, while Fontan failure represents a growing indication for heart transplantation [8]. Heart transplantation has therefore become the potential "fourth stage" [9] or a possible alternative to a high-risk Fontan operation [10] in a strategy of staged palliation for single ventricle physiology. Heart transplant barely accounts for 16% of pediatric solid organ transplants [11]. The thirteenth official pediatric heart transplantation report- 2010 [11] indicates that pediatric recipients received only 12.5% of the total reported heart transplants worldwide. Congenital heart disease is not only the most common recipient diagnosis, but also the most powerful predictor of 1-year mortality after OHT. Results of orthotopic heart transplantations (OHT) for failing single ventricle physiology are mixed. Some authors advocate excellent early and mid-term survival after OHT for failing Fontan [9], while others suggest that rescue-OHT after failing Fontan seems unwarranted [10]. Moreover, OHT outcome appears to be different according to the surgical staging towards the Fontan operation and surgical technique of Fontan completion [12].The focus of this report is a complete review of the recent literature on OHT for failing single ventricles, outlining the clinical issues affecting Fontan failure, OHT listing and OHT outcome. These data are endorsed reporting our experience with OHT for failing single ventricle physiology in recent years.     

Fontan Circulation: Success or Failure?

Fontan surgery represents a milestone in the evolution of congenital heart disease management. It achieved the seemingly improbable (ie, restoration of a noncyanotic state by entirely bypassing the subpulmonary ventricle). In so doing, it has allowed a generation of children who may have otherwise succumbed to their severe congenital heart defect to survive to adulthood. Perfect univentricular physiology is, however, an elusive goal. The Fontan circulation inherently represents a hemodynamic compromise that results in a catalog of potential multiorgan complications. In this review, we explore current knowledge regarding pathophysiology of the failing Fontan, its varied clinical manifestations, and potential therapeutic options. Failure of the Fontan circulation is broadly divided into 3 overlapping categories: ventricular dysfunction, systemic complications of Fontan physiology, and chronic Fontan failure. As long as the Fontan operation continues to serve as the paradigm of care for patients with univentricular hearts, efforts must be directed toward supporting this dynamic circulation that progressively declines in efficiency with age. Continued research in therapies is needed for univentricular dysfunction and systemic complications of Fontan palliation, including potential uses of mechanical support as a bridge to transplantation or as a neosubpulmonary ventricle. Fontan patients remain a major challenge to the medical and surgical community as a whole. Multicentre and multidisciplinary efforts to improve the density and depth of experiences might lead to a better appreciation for, and management of, Fontan failure and its ramifications.     

New concepts: development of a survivorship programme for patients with a functionally univentricular heart

Children with functionally univentricular hearts are now surviving into their third and fourth decades of life. Although survival alone is a remarkable achievement, a lot must still be done to improve the quality and duration of life after the Fontan operation. Challenges that may be faced by these patients include the impact of the Fontan operation on the liver and the density of bone, protein-losing enteropathy, and plastic bronchitis. Paediatric cardiologists are familiar with the haemodynamic issues inherent in Fontan physiology; however, training in cardiology is often not sufficient to give us a complete understanding of the pathophysiology of the complications or of the options for treatment. Collaboration with other subspecialists including gastroenterologists, endocrinologists, and pulmonologists is essential in order to provide the rigorous and nuanced care that our patients need and deserve. A clinic in which a patient can see multiple subspecialists, and in which the subspecialists, as a group, can discuss each patient, can provide a unique and valuable service for patients with a functionally univentricular heart.     

Bidirectional cavopulmonary anastomosis in congenital heart disease. Functional and clinical outcome.

The bidirectional cavopulmonary anastomosis is a surgical procedure suitable for patients with cyanotic congenital heart disease and univentricular physiology. This operation is able to increase the effective pulmonary blood flow without any additional load on the cardiac work and without any further distortion on the pulmonary artery branches. The cavopulmonary anastomosis can represent the first stage for patients destined for Fontan repair or a definitive palliative operation in high risk Fontan candidates. In order to test the hypothesis of a definitive palliation by cavopulmonary anastomosis in this kind of patients, we evaluated the hemodynamic data before and after this surgical approach and compared these data with their clinical and functional outcome. We evaluated 74 patients submitted to bidirectional cavopulmonary anastomosis by either hemodynamic or functional evaluation. End-diastolic and end-systolic ventricular volumes were significantly reduced by bidirectional cavopulmonary anastomosis (p less than 0.0005). Despite these data and a normal ambulatory ECG, spirometry and echocardiographic analysis, the stress test showed discouraging results. In fact, mean work time and peak heart rate were significantly different from normal values showing an impaired functional capacity of these children. In conclusion we think that bidirectional cavopulmonary anastomosis can not be considered an adequate definitive palliation but it represents a very good stage to preserve the pulmonary arteries and to prepare the systemic ventricle towards the Fontan repair.     

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.     

The first successful implantation of an intravenous AAIR pacemaker into autologous extracardiac lateral tunnel Fontan in the child

Patients with a single ventricle have complex anatomy that requires staged palliation which is usually the Fontan procedure. This procedure has undergone a lot of modifications to improve hemodynamics. Despite these efforts, sinus node dysfunction (SND) and bradyarrythmias are still common complications after Fontan operation, therefore there is a need of pacemakers implantation. Unfortunately, the most frequent technique of creating Fontan cannale – the extracardiac lateral tunnel makes the transvenous access to the atrium difficult or impossible to achieve. We report a case of successful implantation of an endocardial atrial lead for SND in patient with an extracardiac autologous Fontan tunnel.     

Novel approaches to direct atrial access after extracardiac fontan palliation

• Catheter access to the “native” atria is limited after extra‐cardiac Fontan palliation of univentricular cardiac defects
• Catheter access to the atria is necessary to percutaneously treat acquired abnormalities after extra‐cardiac Fontan palliation
• Direct trans‐thoracic atrial access and extra‐cardiac conduit puncture is technically straightforward and allows for novel catheter interventions

     

Clinical Approaches to the Patient with a Failing Fontan Procedure

The Fontan operation has been nothing short of revolutionary in its influence on the modern management of patients born with functionally univentricular hearts. The vast majority of these individuals are now surviving well into adulthood. In the 45 years since its introduction, however, there has been increasing recognition of Fontan survivors as a vulnerable population with an altered physiology that has remarkably broad, adverse impact on their long-term health. In this review, the authors discuss the varied manifestations, both cardiac and extracardiac, of the failing Fontan circulation and potential therapeutic options. In addition, a general clinical approach to the patient presenting with Fontan failure is proposed. Ultimately, the key to improving our care and understanding of the Fontan population lies in multi-institutional collaboration and partnership between subspecialty cardiologists and specialists in other organ systems.     

Staged septation of double inlet left ventricle

Complete septation of a double inlet left ventricle with left anterior subaortic outlet chamber was carried out successfully as a staged procedure during the first two years of life in a patient with severe pulmonary hypertension and an abnormal left atrioventricular valve. In contrast with isolated pulmonary artery banding, which rarely has led to a satisfactory septation or modified Fontan operation, this technique achieved good initial palliation and uncomplicated intracardiac repair. It should be considered for infants with univentricular atrioventricular connection, two atrioventricular valves, and excessive pulmonary blood flow.     

Staged septation of double inlet left ventricle.

Complete septation of a double inlet left ventricle with left anterior subaortic outlet chamber was carried out successfully as a staged procedure during the first two years of life in a patient with severe pulmonary hypertension and an abnormal left atrioventricular valve. In contrast with isolated pulmonary artery banding, which rarely has led to a satisfactory septation or modified Fontan operation, this technique achieved good initial palliation and uncomplicated intracardiac repair. It should be considered for infants with univentricular atrioventricular connection, two atrioventricular valves, and excessive pulmonary blood flow.     

Feasibility and safety of immediate perioperative implantation of intravascular stents in cavopulmonary pathways.

Fontan-type procedures are widely used for palliation of patients with many forms of a functional univentricular heart. An ideal Fontan circuit should be free of any distortion or stenosis. The use of stents for the treatment of stenotic and hypoplastic vessels is well established in pediatric cardiac practice. We report the successful use of endovascular stents during the immediate postoperative period in patients undergoing cavopulmonary anastomoses.     

Considerations in Critical-Care and Anesthetic Management of Adult Patients Living With Fontan Circulation

The Fontan procedure is a staged palliation for various complex congenital cardiac lesions, including tricuspid atresia, pulmonary atresia, hypoplastic left heart syndrome, and double-inlet left ventricle, all of which involve a functional single-ventricle physiology. The complexity of the patients’ original anatomy combined with the anatomic and physiologic consequences of the Fontan circulation creates challenges. Teens and adults living with Fontan palliation will need perioperative support for noncardiac surgery, peripartum management for labour and delivery, interventions related to their structural heart disease, electrophysiology procedures, pacemakers, cardioversions, cardiac surgery, transplantation, and advanced mechanical support. This review focuses on the anesthetic and intensive care unit (ICU) management of these patients during their perioperative journey, with an emphasis on the continuity of preintervention planning, referral pathways, and postintervention ICU management. Requests for recipes and doses of medications are frequent; however, as in normal anesthesia and ICU practice, the method of anesthesia and dosing are dependent on the presenting medical/surgical conditions and the underlying anatomy and physiologic reserve. A patient with Fontan palliation in their early 20s attending school full-time with a cavopulmonary connection is likely to have more reserve than a patient in their late 40s with an atriopulmonary Fontan at home waiting for a heart transplant. Each case will require an anesthetic and critical care plan tailored to the situation. The critical care environment is a natural extension of the anesthetic management of a patient, with complex considerations for a patient with Fontan palliation.     

Percutaneous transcatheter closure of a large systemic to pulmonary venous fistulae in an adult patient after extracardiac fontan

Vascular fistulae are frequent complications in patients who have undergone a Fontan operation for palliation of single ventricle physiology. Fistulae involving the pulmonary vasculature may result in progressive hypoxemia, pulmonary hemorrhage, and clinical symptoms. These are commonly managed by percutaneous transcatheter embolization utilizing coils, and more recently, vascular plugs and septal occluders. We present a clinical case of an adult patient who underwent an extracardiac Fontan procedure in childhood for univentricular physiology and presented with symptoms of systemic desaturation 10 years after his surgery. The patient was found to have a large fistula from the inferior vena cava to the right inferior pulmonary vein. The fistula was attempted to be closed with a 12 mm Amplatzer Septal Occluder (St. Jude Medical, St. Paul, MN). Angiography showed continued flow across the fistula, which was then successfully occluded with an 18 mm Amplatzer “Cribriform” Septal Occluder (St. Jude Medical, St. Paul, MN). The patient experienced immediate improvement in his systemic saturation, and demonstrates continued resolution of his symptomatic hypoxia on follow‐up. This case illustrates an uncommon systemic to pulmonary vein fistula after Fontan, and a unique, successful embolization with two septal occluders, resulting in sustained symptomatic improvement. © 2015 Wiley Periodicals, Inc.     

De Vega tricuspid annuloplasty for systemic tricuspid regurgitation in children with univentricular physiology

BACKGROUND AND AIM OF THE STUDY: Significant tricuspid valve regurgitation (TR) is problematic in children with univentricular physiology and a systemic tricuspid valve occasionally requiring tricuspid (systemic atrioventricular) valve replacement. Since 1998, the De Vega tricuspid annuloplasty technique has been applied for TR in these children. METHODS: Twelve children (median age 2.2 years; range: 6 months to 17 years) with moderate or severe systemic TR underwent a De Vega tricuspid annuloplasty during a bidirectional Glenn anastomosis (n = 3), Fontan procedure (n = 8) or aortic valve replacement late after a Fontan procedure (n = 1). Nine patients (75%) had prior Norwood palliation for hypoplastic left heart syndrome. Four patients had simultaneous repair of an abnormal tricuspid valve in addition to the De Vega procedure. RESULTS: There were no deaths during a mean follow up of 2.0 +/- 1.4 years (range: 6 months to 5.1 years). One child required pacemaker implantation early after operation, and one child with a Glenn anastomosis underwent cardiac transplantation 21 months postoperatively. In the remaining 11 patients, the most recent echocardiogram showed mild or no TR in eight children, mild-to-moderate TR in one child, and moderate TR in two children. No child had symptomatic TR (including the two with moderate TR), significant tricuspid stenosis, or late pacemaker implantation. CONCLUSION: The De Vega tricuspid annuloplasty safely provides excellent relief of systemic TR in children with univentricular physiology, with a majority of patients (73%) having mild or less residual TR at follow up examination. This simple technique is preferred to tricuspid (systemic) valve replacement in these children.     

Staged Single‐ventricle Palliation in 2011: Outcomes and Expectations

Outcomes for staged palliation for single‐ventricle heart disease have improved over the past two decades. As outcomes improve, parental expectations for survival and quality of life have risen accordingly. Nevertheless, the number of interventions and complications these patients must endure remain high. The final surgical destination of the single‐ventricle patient, the total cavopulmonary connection (or Fontan operation) successfully separates systemic venous and pulmonary venous blood flow but does so at great cost. Fontan patients remain at significant risk of complications despite what are perceived to be “favorable” hemodynamics. The outcomes in this population are discussed in this review, with particular attention to the history behind our current strategies as well as to recent salient studies.     

Fontan operation. Hemodynamic factors associated with postoperative outcomes

Introduction and objectives

The Fontan operation is usually the final palliative procedure in patients with univentricular heart. The objectives of this study were, firstly, to describe the clinical and haemodynamic characteristics of a group of patients with univentricular physiology who had previously been palliated with a bidirectional Glenn procedure and, secondly, to identify risk factors that can influence postoperative outcomes after the Fontan operation.

Methods

Retrospective study with 32 patients who underwent a Fontan operation between March 2000 and December 2009. Clinical characteristics, catheterization data, type and duration of surgery were revised and analyzed as predictors of postoperative outcome.

Results

Hospital mortality was 3%. After a median follow-up of 44 months (interquartile range, 32-79), survival was 90%. Preoperative mean pulmonary artery pressure (measured during catheterization) was correlated with late mortality. Of the remaining variables analyzed, the Nakata and McGoon indices, and duration of cardiopulmonary bypass showed the highest correlations with postoperative outcomes. Interventional catheterization before the Fontan operation was performed in 42% of patients.

Conclusions

Hospital mortality after the Fontan operation was very low. The performance of a haemodynamic study before the Fontan operation made it possible to select high-risk patients for surgery as well as permitting the performance of interventional procedures that could improve postoperative outcome in these patients.Full English text available from:www.revespcardiol.org     

Usefulness of cardiac magnetic resonance imaging combined with low-dose dobutamine stress to detect an abnormal ventricular stress response in children and young adults after fontan operation at young age

After Fontan operation, patients are limited in increasing cardiac output and in exercise capacity. This has been related to impaired preload or other factors leading to decreased global ventricular performance with stress. To study these factors, the stress responses of functionally univentricular hearts were assessed at rest and during low-dose dobutamine stress using cardiovascular magnetic resonance imaging. Thirty-two patients after Fontan completion at young age were included (27 with total cavopulmonary connection, 5 with atriopulmonary connection; mean age 13.3 years, range 7.5 to 22.2; 23 male patients; median follow-up after Fontan operation 8.1 years, range 5.2 to 17.8). A multiphase short-axis stack of 10 to 12 contiguous slices of the systemic ventricle was obtained at rest and during low-dose dobutamine stress cardiovascular magnetic resonance imaging (maximum 7.5 microg/kg/min). With stress-testing, heart rate, ejection fraction, and cardiac index increased adequately (p <0.001). There was an abnormal decrease in end-diastolic volume and an adequate decrease in end-systolic volume (p <0.001). Stroke volume did not change with stress testing (p = 0.15). At rest, dominant left ventricles had higher ejection fractions than dominant right ventricles (p = 0.01), but this difference disappeared with stress testing. In conclusion, a functionally univentricular heart after Fontan completion at young age has an adequate increase in ejection fraction with beta-adrenergic stimulation. However, as a result of impaired preload with stress, cardiac output can be increased only by increasing heart rate.