Congenital: Fontan
Cavopulmonary assist: Long-term reversal of the Fontan paradox
Fontan circulatory inefficiency can be addressed by replacing the missing subpulmonary power source to reverse the Fontan paradox. An implantable cavopulmonary assist device is described that will simultaneously reduce systemic venous pressure and increase pulmonary arterial pressure, improving preload and cardiac output, in a univentricular Fontan circulation on a long-term basis.Commentary: The future fourth stage of single-ventricle palliation
Five decades after Francis Fontan first described his procedure for palliation of tricuspid atresia, modified versions have enabled long-term survival of a broad array of patients with univentricular circulation.1 It has long been recognized, however, that the sequelae of the total cavopulmonary connection—including systemic venous congestion, hepatic dysfunction, renal insufficiency, changes in pulmonary vascular physiology, and elevated systemic afterload—result in long-term failure of even the “perfect” Fontan circulation.Commentary: Engineering an optimal mechanical circulatory support system for the cavopulmonary connection
Long-term survival of the patients with a functional single-ventricle physiology has dramatically improved with the establishment of staged surgical palliation and subsequent Fontan operation. As the number of the patients who live with a Fontan circulation has been increasing exponentially, management of the failing Fontan circulation becomes one of the most critical issues in pediatric and adult congenital heart disease care. Dr Trusty and colleagues1 reported an in vitro analysis of the mechanical circulatory support (MCS) system for failing Fontan circulation using a PediMag (Thoratec Corp, Pleasanton, Calif) or CentriMag (Thoratec Corp) centrifugal pump.Commentary: Fontan assist device support: Road map to “stage 4” palliation
The “un-natural” history of the Fontan circulation portends a rather grim long-term outlook for patients with single ventricle congenital heart disease. Decades of experience with the Fontan circulation have shown the advantages of the total cavopulmonary connection that minimizes power loss to improve subpulmonary flow efficiency; yet, the altered hemodynamics impart a chronic attrition to the organ systems of the body leading to a range of complications and limited life expectancy for this patient cohort.Commentary: Subpulmonary pump in Fontan circulation: Can it be a breakthrough in treatment of the single ventricle?
It has been almost half a century since the first successful report of Fontan surgery.1 Without any doubt, this was one of the major breakthroughs in the history of cardiac surgery and brought a ray of light to a previously unrepairable and lethal heart condition. However, long-term survival after the Fontan operation is still far from satisfactory.2 Efforts to improve survival to date have focused on optimization of the design of the Fontan circuit per se to make the best use of the single energy source from the single ventricle.Y-graft modification to the Fontan procedure: Increasingly balanced flow over time
The use of Y-grafts for Fontan completion is hypothesized to offer more balanced hepatic flow distribution (HFD) and decreased energy losses. The purpose of this study was to evaluate the hemodynamic performance of Y-grafts over time using serial cardiac magnetic resonance data and to compare their performance with extracardiac Fontan connections.An in vitro analysis of the PediMag and CentriMag for right-sided failing Fontan support
Right-sided mechanical circulatory support for failing Fontan physiology has been largely unsuccessful due to inherent hemodynamic differences between these patients and the target populations for most assist devices. This study uses advanced benchtop modeling of Fontan physiology to examine the use of PediMag and CentriMag to improve failing Fontan hemodynamics.Evaluation of pulmonary endothelial function in Fontan patients
Pulmonary endothelial dysfunction due to a loss of pulsatile pulmonary blood flow is thought to be a major contributor in the development of increased pulmonary vascular resistance (PVR) in patients with a Fontan circulation. We sought to evaluate pulmonary endothelial dysfunction by vasodilator response to acetylcholine in children and adolescents with Fontan hemodynamics.Commentary: Dream big in every small step
The last stage of surgical single-ventricle palliation has undergone ingenious modifications since its first description.1 The achievement of a higher arterial saturation level by the separation of the venous backflow from the systemic circulation at the cost of a passive, nonpulsatile pulmonary blood supply and higher systemic venous pressure has led to the initially successful but challenging Fontan physiology in the longer follow-up.2,3 By consideration of various etiologies for an ultimately failing Fontan circulation, the search for the optimal fourth stage palliation strategy continues, with remarkable future potential.Another step toward intelligent surgical planning
The applications of computational fluid dynamics (CFD) to cardiovascular medicine and surgery just keep getting better. Trusty and colleagues1 examine a way that CFD could be used to plan “complex” Fontan operations. These patients are those whose anatomy does not “guarantee” a relatively even distribution of hepatic blood flow (HBF) to both lungs with a conventional extracardiac conduit or lateral tunnel. The typical example would be an interrupted inferior vena cava with azygous continuation to a left superior vena cava and a right-sided hepatic veins-to-right pulmonary artery conduit.The first cohort of prospective Fontan surgical planning patients with follow-up data: How accurate is surgical planning?
Fontan surgical planning is an image-based, collaborative effort, which is hypothesized to result in improved patient outcomes. A common motivation for Fontan surgical planning is the progression (or concern for progression) of pulmonary arteriovenous malformations. The purpose of this study was to evaluate the accuracy of surgical planning predictions, specifically hepatic flow distribution (HFD), a known factor in pulmonary arteriovenous malformation progression, and identify methodological improvements needed to increase prediction accuracy.Aortic arch reconstruction in the Norwood operation: It is more than just geometry
Much attention has been given to the reconstructed aortic arch anatomy in the Norwood operation with regard to hypoplastic left heart syndrome (HLHS) outcomes. Having the arch too big, leaving or residual obstruction or having it develop, and using patch material have all been implicated in poor results after the Norwood procedure. Knowing that the right ventricle may struggle as the systemic ventricle long-term, more data are being sought with regard to the abnormal afterload imposed on the right ventricle by a reconstructed aortic arch.Influence of aortic stiffness on ventricular function in patients with Fontan circulation
Elastic properties of the thoracic aorta are responsible for buffering systemic afterload, and may be particularly important in patients with Fontan circulation, in whom heart failure is a major source of attrition. The purpose of this study was to characterize regional stiffness in the ascending and descending aorta in patients with hypoplastic left heart syndrome and single left ventricle morphology after Fontan operation by cardiac magnetic resonance imaging, and to assess whether changes in aortic stiffness are associated with the ventricular function.Elucidating the mechanisms of infective endocarditis in bovine jugular vein conduits: Are we any closer?
Multiple reports have raised concerns regarding the high rates of late endocarditis in bovine jugular vein (BJV) grafts used for right ventricular outflow tract reconstruction as conduits1,2 (Figure 1) or as percutaneously placed stent-mounted valves.3,4 The pathophysiologic mechanisms for these findings remain unclear.Are plasma proteins key players in the pathogenesis of infective endocarditis?
Infective endocarditis (IE) after the implantation of a bovine jugular vein (BJV) graft in the right ventricular outflow tract has recently been described to be more frequent than for other conduits.1 Yet, the exact mechanisms that drive this phenomenon are under discussion. Jalal and colleagues2 were the first to study bacterial adhesion to different tissues in vitro; their clinical bacterial isolates displayed increased adherence to BJV valves, as compared with bovine and porcine pericardium, especially in traumatized valve leaflets.Francis Fontan memorial 1929-2018
Francis Fontan was born in Nay, in the province of Bearn in France. His father, Victor, was a noted professional cyclist and achieved fame as the “King of Mountains” in the Tour de France.What matters more in testing bacterial adhesion: Flow conditions or choice of bacterial strain?
We read with great interest the work published by Veloso and colleagues1 that investigated the bacterial adherence to pulmonary valve graft tissues under static and flow conditions. These experiments were achieved using wild bacterial strains of Staphylococcus aureus, Staphylococcus epidermidis, and Streptococcus sanguinis and the following valvular substrates: bovine pericardium patch, bovine jugular vein, and cryopreserved homograft. The authors concluded that the surface composition of bovine jugular vein and homograft tissues themselves, bacterial surface proteins, and shear forces per se were not the prime determinants of bacterial adherence.Still young at heart…
Surgical palliation for single-ventricle (SV) physiology has continued to improve over the last 40 years. Since the original description of the Fontan operation for tricuspid atresia in 1971,1 the procedure has undergone several modifications and is now used to palliate a wide range of SV defects. Most patients with SV lesions require some form of neonatal palliation to ensure unrestricted systemic and pulmonary blood flow and free mixing of blood within the heart. Invariably, first-stage palliation results in a volume-loaded ventricle, as pulmonary resistance decrease with age.Cause versus effect? Tricuspid valve replacement in the management of a failing Fontan circulation
Management of single-ventricle physiology after completion Fontan continues to produce improved outcomes and transplant-free quality of life metrics. Single-ventricle survivorship clinics and other focused care delivery models within congenital heart programs provide multidisciplinary care across all medical components of need for these complex patients.1 Despite these advances, however, transplantation remains a common end pathway for these palliated patients. Creation of a medical and social environment that is best for patients to prepare for this “final” surgical stage confounds even the most advanced institutions.Long-term outcome of preadolescents, adolescents, and adult patients undergoing total cavopulmonary connection
Patients with a single ventricle infrequently undergo total cavopulmonary connection as preadolescents, adolescents, or adults. The purpose of this study was to clarify the characteristics of this cohort and to analyze the factors influencing outcomes.High incidence of late infective endocarditis in bovine jugular vein valved conduits
Bovine jugular vein (BJV) grafts (Medtronic, Inc, Minneapolis, Minn) are used to restore right ventricle-to-pulmonary artery continuity. Recent studies have associated these grafts with the development of infective endocarditis. The purpose of this study was to report the incidence of endocarditis in BJV grafts.Tricuspid valve replacement in failing Fontan circulation with severe ventricular dysfunction: The road not taken?
In patients with hypoplastic left heart syndrome (HLHS) and right ventricular (RV) dilatation and failure, tricuspid valve (TV) replacement is rarely performed after Fontan completion.1 Listing for heart transplantation, or considering long-term mechanical circulatory support as a bridge to transplantation, is the conventional approach.2 We describe a patient with HLHS and failing Fontan circulation, with severe RV dilatation and severe TV regurgitation. The patient was not a candidate for heart transplantation.Fontan-associated liver disease: Is it all about hemodynamics?
The study by Trusty et al,1 in this issue of The Journal of Thoracic and Cardiovascular Surgery, aims at investigating detailed cardiac magnetic resonance (CMR)-derived flow dynamics and total cavopulmonary connection (TCPC) energetics as potential risk factors for hepatic fibrosis in Fontan patients. Fontan-associated liver disease (FALD) has been a well documented complication for decades2 and is now recognized as a progressive process affecting all Fontan survivors. The exact causes and risk factors of FALD remain poorly understood.Cow neck veins and endocarditis: A mooo…ving mystery
Surgeons loathe endocarditis—it kills patients and causes morbidity. Moreover, nothing puts a damper on a surgeon's day like a multiple redo sternotomy and inadvertent rupture of an endocarditic conduit. Therefore, the report by Beckerman and colleagues1 of increased risk of infective endocarditis (IE) with bovine jugular vein (BJV) conduits (Medtronic Inc, Minneapolis, Minn), which is a notable addition to the growing literature on this topic, is certainly concerning. At a median follow-up of 7.5 years, IE occurred in 10% of 253 BJV conduits, 0.8% of 506 homografts, and 1.9% of 269 porcine heterografts.Impact of hemodynamics and fluid energetics on liver fibrosis after Fontan operation
The staged Fontan procedure has shown promising short-term outcomes in patients with single ventricles. However, Fontan-associated liver disease is a marked problem as patients age. The purpose of this study is to investigate the relationship between hemodynamics and liver fibrosis in patients undergoing the Fontan.
