The Fontan procedure: evolution in technique; attendant imperfections and transplantation for "failure"

Intraventricular Flow Simulations in Singular Right Ventricles Reveal Deteriorated Washout and Low Vortex Formation

Purpose

Patients with a functionally univentricular heart represent one of the most common severe cardiac lesions with a prevalence of 3 per 10,000 live births. Hemodynamics of the singular ventricle is a major research topic in cardiology and there exists a relationship between fluid dynamical features and cardiac behavior in health and disease. The aim of the present work was to compare intraventricular flow in single right ventricle (SRV) patients and subjects with healthy left hearts (LV) through patient-specific CFD simulations.

Methods

Three-dimensional real-time echocardiographic images were obtained for five SRV patients and two healthy subjects and CFD simulations with a moving mesh methodology were performed. Intraventricular vortex formation and vortex formation time (VFT) as well as the turbulent kinetic energy (TKE) and ventricular washout were evaluated.

Results

The results show significantly lower values for the VFT and the TKE in SRV patients compared with healthy LV subjects. Furthermore, vortex formation does not progress to the apex in SRV patients. These findings were confirmed by a significantly lower washout in SRV patients.

Conclusions

The study pinpoints the intriguing role of intraventricular flows to characterize performance of SRVs that goes beyond standard clinical metrics such as ejection fraction.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13239-021-00598-9.

Atrial arrhythmias and thromboembolic complications in adults post Fontan surgery

Objective

Patients with Fontan surgery experience late complications in adulthood. We studied the factors associated with the development and maintenance of atrial arrhythmias and thromboembolic complications in an adult population with univentricuar physiology post Fontan surgery.

Methods

Single centre retrospective cohort study of patients ≥18 years of age with Fontan circulation followed at our quaternary care centre for more than 1 year were included. Univariate and multivariate regression models were used where applicable to ascertain clinically significant associations between risk factors and complications.

Results

93 patients were included (age 30.2±8.8 years, 58% men). 28 (30%) had atriopulmonary Fontan connection, 35 (37.6%) had lateral tunnel Fontan and 29 (31.1%) had extracardiac Fontan pathway. After a mean of 7.27±5.1 years, atrial arrhythmia was noted in 37 patients (39.8%), of which 13 developed had atrial fibrillation (14%). The presence of atrial arrhythmia was associated with the number of prior cardiac surgeries/procedures, increasing age and prior atriopulmonary Fontan operation. Thromboembolic events were present in 31 patients (33%); among them 14 had stroke (45%), 3 had transient ischaemic attack (9.7%), 7 had pulmonary embolism (22.6%) and 5 had atrial thrombus with imaging (16.1%). The presence of thromboembolic events was only associated with age and the presence of cirrhosis in multivariate analysis.

Conclusions

Atrial arrhythmias are common in adults with Fontan circulation at an early age, and are associated with prior surgical history and increasing age. Traditional risk factors may not be associated with atrial arrhythmia or thromboembolism in this cohort.

Benign Hepatic Nodules Mimicking Hepatocellular Carcinoma in the Setting of Fontan-associated Liver Disease: A Case Report

Fontan procedure, in which systemic circulation is redirected into pulmonary circulation by a baffle, is a palliative surgical strategy for patients born with single ventricle congenital heart disease. Hemodynamic changes secondary to Fontan procedure, also termed as Fontan physiology, result in end-organ damage, especially of the liver. Fontan-associated liver disease (FALD) represents a spectrum of pathologies ranging from mild liver fibrosis to advanced liver cirrhosis and hepatocellular carcinoma (HCC). Hepatic nodules, some of which have been documented as HCC in several case series and reports, are a recognized complicated feature of FALD. Herein, we report a case with benign hepatic nodules mimicking HCC by imaging characteristics, emphasizing the fact that arterially enhancing lesions with delayed washout appearance may reflect benign regenerative or focal nodular hyperplasia-like nodules in patients with Fontan physiology.

The Use of Fecal Calprotectin Levels in the Fontan population

The Fontan procedure was first performed in the seventies as a palliation for patients with single ventricle physiology. A feared complication after a Fontan procedure is the development of protein losing enteropathy (PLE). Systemic inflammation has a negative effect on the intestinal barrier integrity, which has supported the use of steroids in this setting. To the best of our knowledge there are no studies linking intestinal inflammation in patients with PLE after Fontan. The objective of this study was to identify the presence of intestinal inflammation measured by FC in patients with PLE after a Fontan procedure. A cross-sectional analysis was performed examining 23 stool samples from 23 Fontan patients for both Fecal alpha-1-antitrypsin (FA1AT) and FC with and without PLE. The median FC was 21 mcg/gm of stool (IQR: 15.7-241 mcg/gm of stool), and the median FA1AT was 40 mg/dL (IQR: 30-220 mg/dL). The median FC and FA1AT were significantly higher in the PLE group than in the Non-PLE group (p = 0.002 and p < 0.0001, respectively). Significantly elevated levels of FC were demonstrated in Fontan patients with PLE, which correlated with the elevated levels of FA1AT. Inversely, levels of FC in Fontan patients without suspected PLE were within the normal range. To our knowledge, this is the first study to demonstrate intestinal inflammation using FC in the setting of PLE within this cohort, and may prove to be useful as a diagnostic tool in its treatment.

The evolving role of the total artificial heart in the management of end-stage congenital heart disease and adolescents

Advances in medical therapies have yielded improvement in morbidity and a decrease in mortality for patients with congenital heart disease, both surgically palliated and uncorrected. An unintended consequence is a cohort of adolescent and adult patients with heart failure who require alternative therapies. One intriguing option is placement of a total artificial heart (TAH) either as a bridge to transplant or as a destination therapy. Of the 1091 Jarvik-7 type TAH (Symbion, CardioWest and SynCardia) placed between 1985 and 2012, only 24 have been performed in patients with congenital heart disease, and a total of 51 were placed in patients younger than 21. At our institution, the SynCardia TAH was implanted in a 19-year-old patient with cardiac allograft failure because of chronic rejection and related multisystem organ failure including need for hemodialysis. Over the next year, she was nutritionally and physically rehabilitated, as were her end organs, allowing her to come off dialysis, achieve normal renal function and eventually be successfully transplanted. Given the continued growth of adolescent and adult congenital heart disease populations with end-stage heart failure, the TAH may offer therapeutic options where previously there were few. In addition, smaller devices such as the SynCardia 50/50 will open the door for applications in smaller children. The Freedom Driver offers the chance for patients to leave the hospital with a TAH, as does the AbioCor, which is a fully implantable TAH option. In this report, we review the history of the TAH and potential applications in adolescent patients and congenital heart disease.

Decision-Making for Surgery in the Management of Patients with Univentricular Heart

A series of technical refinements over the past 30 years, in combination with advances in perioperative management, have resulted in dramatic improvements in the survival of patients with univentricular heart. While the goal of single-ventricle palliation remains unchanged - normalization of the pressure and volume loads on the systemic ventricle, the strategies to achieve that goal have become more diverse. Optimal palliation relies on a thorough understanding of the changing physiology over the first years of life and the risks and consequences of each palliative strategy. This review describes how to optimize surgical decision-making in univentricular patients based on a current understanding of anatomy, physiology, and surgical palliation.

Liver disease related to the heart

In this article, we review both acute and chronic liver diseases that occur as a result of heart or circulatory system failure. Ischemic hepatitis, congestive hepatopathy, cardiac cirrhosis, and Fontan liver disease are reviewed. We review clinical presentation, diagnostic data, prognosis, and available therapeutic strategies for these entities. We aim to increase awareness about cardio-hepatic disease as the prevalence of this disorder in adults is increasing. Due to advances in medical and surgical care, patients with heart disease are living longer and thus exposing long-term effects on the liver that are clinically relevant. There may be a role for dual organ transplantation in some cases, but this is a very challenging endeavor, and newer ideas about treatment or prevention are needed.

Demographic characteristics and estimated prevalence of Fontan-associated plastic bronchitis

Plastic bronchitis (PB) is a poorly understood disease that can complicate any underlying pulmonary disease. However, it appears to most often occur in patients with surgically palliated congenital heart disease, particularly after the Fontan procedure. Few data exist about the prevalence and etiology of PB in this population. In an effort to establish data about prevalence, we conducted a retrospective study of an existing Fontan surgery database (n = 654) comprised of data, including sex, age at date of surgery, alive/dead status, New York Heart Association classification at last follow-up, right-ventricular end-diastolic pressure and pulmonary artery pressure before Fontan surgery, and the presence of a Fontan fenestration. An initial medical record review of 173 patients in the database who were followed at the University of Michigan identified seven patients with PB resulting in an estimated prevalence of 4 %. Subsequently, 14 % of 211 surveyed patients reported that they presently expectorate mucus or fibrin plugs (casts). Demographic and clinical variables did not differ between patients with or without possible PB. Collectively, these findings suggest that Fontan patients presently with PB may range from 4 to 14 %, indicating potential under-diagnosis of the disease. There were no remarkable physical or hemodynamic indicators that differentiated patients with or without possible PB. These data also highlight the need for more elaborate, prospective studies to improve our understanding of PB pathogenesis so that more definitive diagnostic criteria for this devastating disease can be established and its prevalence more accurately determined.

Congenital heart disease and the liver

There are approximately 1 million adult patients with congenital heart disease (CHD) in the United States, and the number is increasing. Hepatic complications are common and may occur secondary to persistent chronic passive venous congestion or decreased cardiac output resulting from the underlying cardiac disease or as a result of palliative cardiac surgery; transfusion or drug-related hepatitis may also occur. The unique physiology of Fontan circulation is particularly prone to the development of hepatic complications and is, in part, related to the duration of the Fontan procedure. Liver biochemical test abnormalities may be related to cardiac failure, resulting from intrinsic liver disease, secondary to palliative interventions, or drug related. Complications of portal hypertension and, rarely, hepatocellular carcinoma (HCC) may also occur. Abnormalities such as hypervascular nodules are often observed; in the presence of cirrhosis, surveillance for HCC is necessary. Judicious perioperative support is required when cardiac surgery is performed in patients with advanced hepatic disease. Traditional models for liver disease staging may not fully capture the severity of disease in patients with CHD. The effectiveness or safety of isolated liver transplantation in patients with significant CHD is limited in adults; combined heart-liver transplantation may be required in those with decompensated liver disease or HCC, but experience is limited in the presence of significant CHD. The long-term sequelae of many reparative cardiac surgical procedures are not yet fully realized; understanding the unique and diverse hepatic associations and the role for early cardiac transplantation in this population is critical. Because this population continues to grow and age, consideration should be given to developing consensus guidelines for a multidisciplinary approach to optimize management of this vulnerable population.

The Fontan Connections: Past, Present, and Future

The Fontan procedure is now considered the final common pathway for patients with anatomical or functional single ventricle. These patients initially have their systemic and pulmonary circulations in parallel, supported by one functional ventricular chamber. The ultimate goal with this procedure is to separate the two circulations, to prevent mixing of venous and arterial blood, and to provide adequate tissue oxygenation. The objective of this article is to review the Fontan procedure with its various modifications and refinements since its introduction to clinical practice in 1971, by Fontan and Baudet.

Cardiac Transplantation and Mechanical Support for Functional Single Ventricle

Cardiac transplantation has played a pivotal role in the therapeutic algorithm for anatomically uncorrectable congenital heart disease, particularly the failing single ventricle. The historical evolution from Kantrowitz to Bailey and beyond challenges the application of this scarce resource to complex cardiac malformations in the presence of physiologic and circulatory failure. While selection of cardiac transplantation as primary therapy for hypoplastic-left heart syndrome is currently rare, the failing single ventricle in various stages of the Fontan pathway is increasingly considered for this therapy. The results of transplantation in this complex situation have progressively improved and now approached the late outcomes for other conditions. Mechanical circulatory support for the failing single ventricle has recently carried infants and children to successful transplant. The development of miniaturized continuous flow pumps offers the hope of major new avenues of successful circulatory support for single ventricle patients.

Successful management of plastic bronchitis in a child post Fontan: case report and literature review

PURPOSE

Plastic bronchitis is the occlusion of the major bronchial airways by a firm, gelatinous mucoid cast. It is a rare condition, which while classically described in asthma and sickle cell disease has greater mortality in patients with congenital heart disease. The management of this disease is obscure given the lack of clinical data regarding treatment therapies.

METHODS

We describe a case of an 11-year-old female status after Fontan surgery who presented with respiratory distress secondary to atelectasis of the right lung.

RESULTS

A bronchoscopy was performed demonstrating an obstructing bronchial cast with successful extraction. The plastic bronchitis continued to recur and she was placed on multiple inhaled mucolytics as well as inhaled tissue plasminogen activator with temporary resolution. Further evaluation of the etiology of her casts revealed that she had elevated pulmonary arterial pressures. Repeated bronchoscopic removal of the casts was utilized as well as continuation of the aggressive airway clearance. Ultimately fenestration of her Fontan was performed along with treatment of pulmonary vasodilators sildenafil and bosentan. Although there was improvement of the cast formation, her airway clearance could only be weaned to four times a day therapy with which she was discharged home after a 3-month hospitalization. She continues to remain on this therapy and has not required hospitalization since the initial incident over 1 year ago.

CONCLUSIONS

Plastic bronchitis in a patient with Fontan physiology presents a treatment dilemma that may require comprehensive therapy in severe cases such as described.