Fontan completion without surgery

Transcatheter Fontan completion: Creation of an extracardiac Fontan

Patients with functionally univentricular hearts are usually palliated surgically. There have been several reports of successful attempts to complete the Fontan procedure without surgery. The pathways created at the time of the preconditioning were largely reminiscent of the lateral tunnel Fontan. However, this approach is still confidentially limited to a small number of centers. In 2013, we designed a circuit that mimics the actual surgical technique of extracardiac total cavopulmonary connection to allow for transcatheter completion in an animal study. A polytetrafluoroethylene conduit was connected between the pulmonary artery and the inferior vena cava (IVC). The superior anastomosis was occluded to avoid flow between IVC and superior vena cava (SVC). The conduit was connected to the right atrium (RA) and a large fenestration was created to allow free flow from the IVC to the RA. Extrapolating our approach, a center reported the successful transcatheter completion of an extracardiac Fontan in a 6-year-old child. However, this technique is not directly transposable to our population of patients who require preconditioning in infancy. We report here an innovative extension of this technique that may allow preparing patients in infancy, ideally at the time of the Glenn in the future, to receive an extracardiac Fontan at 2 years/11 kg without additional surgery.

Transcatheter interventions in patients with a Fontan circulation: Current practice and future developments

The Fontan operation represents the last of multiple steps that are offered a wide range of congenital cardiac lesions with a single ventricle (SV) physiology. Nowadays this surgical program consists of a total cavopulmonary connection (TCPC), by anastomosing systemic veins to the pulmonary arteries (PAs), excluding the right-sided circulation from the heart. As a result of imaging, surgical, percutaneous, and critical care improvements, survival in this population has steadily increased. However, the Fontan physiology chronically increases systemic venous pressure causing systemic venous congestion and decreased cardiac output, exposing patients to the failure of the Fontan circulation (FC), which is associated with a wide variety of clinical complications such as liver disease, cyanosis, thromboembolism, protein-losing enteropathy (PLE), plastic bronchitis (PB), and renal dysfunction, ultimately resulting in an increased risk of exercise intolerance, arrhythmias, and premature death. The pathophysiology of the failing Fontan is complex and multifactorial; i.e., caused by the single ventricle dysfunction (diastolic/systolic failure, arrhythmias, AV valve regurgitation, etc.) or caused by the specific circulation (conduits, pulmonary vessels, etc.). The treatment is still challenging and may include multiple options and tools. Among the possible options, today, interventional catheterization is a reliable option, through which different procedures can target various failing elements of the FC. In this review, we aim to provide an overview of indications, techniques, and results of transcatheter options to treat cavopulmonary stenosis, collaterals, impaired lymphatic drainage, and the management of the fenestration, as well as to explore the recent advancements and clinical applications of transcatheter cavopulmonary connections, percutaneous valvular treatments, and to discuss the future perspectives of percutaneous therapies in the Fontan population.

Improved Technique for Interventional Extracardiac Fontan

We have previously reported a simple technique for preparatory staging and subsequent interventional completion of an extracardiac Fontan procedure that anatomically and hemodynamically closely mimics a standard extracardiac Fontan. We describe herein modifications that simplify the original procedural sequence and that may allow wider application. Percutaneous completion can be achieved even without a radiofrequency probe, using electrocautery. Fenestration is also easy to perform if there is a clinical indication.

Transcatheter Fontan completion using novel balloon and stent system

Despite advances in percutaneous interventions, transcatheter Fontan completion remains experimental and performed only in select cases. Non-surgical Fontan completion requires surgical preconditioning at an earlier stage of palliation. We describe transcatheter Fontan completion in a 15-year-old male with previously failed surgical Fontan palliation without surgical preconditioning.

Hypoplastic left heart syndrome [HLHS]: treatment options in present era

Hypoplastic left heart syndrome (HLHS) is the most severe form of congenital heart defect (CHD). The first successful intervention for it was undertaken by Norwood in 1983. Since then, there have been much development in the pre, intra, and postoperative treatment option in staged palliative surgical procedures. Early diagnostic management, prenatal interventions, innovative diagnostic methods, constantly modified surgical techniques, and hybridization contribute to a significant progress in treatment options. This will allow for defining an optimal strategy of improving survival and quality of life in HLHS patients. The development of intervention cardiology makes possible the stepwise treatment of the defect with one operation only. The first and third stage may be done by hybrid or interventional methods, then only the second stage of treatment needs to be done surgically. The world experience and all the available literature says that the 1st-stage procedure could be done now safely either directly or with a bridge to Norwood followed by the stage 2 with a Glen or Hemi-Fontan and followed by a Fontan down the lane surgically.

Approaches to Establish Extracardiac Total Cavopulmonary Connections in Animal Models—A Review

Background:

Long-term survival of patients with a single ventricle palliated with a Fontan procedure is still limited. No curative treatment options are available. To investigate the pathophysiology and potential treatment options, such as mechanical circulatory support (MCS), appropriate large animal models are required. The aim of this review was to analyze all full-text manuscripts presenting approaches for an extracardiac total cavopulmonary connection (TCPC) animal model to identify the feasibility and limitations in the acute and chronic setting.

Methods:

A literature search was performed for full-text publications presenting large animal models with extracardiac TCPCs on Pubmed and Embase. Out of 454 reviewed papers, 23 manuscripts fulfilled the inclusion criteria. Surgical procedures were categorized and hemodynamic changes at the transition from the biventricular to the univentricular condition analyzed.

Results:

Surgical procedures varied especially regarding coronary venous flow handling and anatomic shape of the TCPC. In most studies (n = 14), the main pulmonary artery was clamped and the coronary venous flow redirected by additional surgical interventions. Only in five reports, the caval veins were connected to the right pulmonary artery to create a true TCPC shape, whereas in all others (n = 18), the veins were connected to the main pulmonary artery. An elevated pulmonary vascular resistance was identified as a limiting hemodynamic factor for TCPC completion in healthy animals.

Conclusions:

A variety of acute TCPC animal models were successfully established with and without MCS, reflecting the most important hemodynamic features of a Fontan circulation; however, chronic animal models were not reported.

Cardiovascular anatomy in children with bidirectional Glenn anastomosis, regarding the transcatheter Fontan completion

BACKGROUND

Transcatheter stent-secured completion of total cavopulmonary connection (TCPC) after surgical preparations during the Glenn anastomosis procedure has been reported, but complications from this approach have precluded its clinical acceptance.

AIMS

To analyse cardiovascular morphology and dimensions in children with bidirectional Glenn anastomosis, regarding the optimal device design for transcatheter Fontan completion without special surgical "preconditionings".

METHODS

We retrospectively analysed 60 thoracic computed tomography and magnetic resonance angiograms performed in patients with a median age of 4.1 years (range: 1.8-17.1 years). Additionally, we simulated TCPC completion using different intra-atrial stent-grafts in a three-dimensional model of the representative anatomy, and performed calculations to determine the optimal stent-graft dimensions, using measured distances.

RESULTS

Two types of cardiovascular arrangement were identified: left atrium interposing between the right pulmonary artery (RPA) and inferior vena cava, with the right upper pulmonary vein (RUPV) orifice close to the intercaval axis (65%); and intercaval axis traversing only the right(-sided) atrial cavity, with the RUPV located posterior to the atrial wall (35%). In the total population, the shortest median RPA-to-atrial wall distance was 1.9mm (range: 0.6-13.8mm), while the mean intra-atrial distance along the intercaval axis was 50.1±11.2mm. Regardless of the arrangement, 83% of all patients required a deviation of at least 5.9±2.4mm (range: 1.2-12.7mm) of the stent-graft centre at the RUPV level anteriorly to the intercaval axis to avoid covering or compressing this vein. Fixing the anterior deviation of the curved stent-graft centre at 10mm significantly decreased the range of bend angle per every given RUPV-RPA distance.

CONCLUSIONS

For both types of cardiovascular arrangement, after conventional bidirectional Glenn anastomosis, the intra-atrial curved stent-graft seemed most suitable for achieving uncomplicated TCPC completion percutaneously without previous surgical "preconditionings" in the majority of children. Experimental study is necessary to validate this conclusion.

A Simplified Technique for Interventional Extracardiac Fontan

Purpose:

We report a simple technique for an interventional extracardiac Fontan (ECF) procedure.

Description:

At the preparatory stage along with a bidirectional cavopulmonary connection (BCPC; cardiopulmonary bypass), a short piece of polytetrafluoroethylene (PTFE) tube graft is anastomosed to the inferior surface of the right pulmonary artery. Another longer PTFE graft is anastomosed to the transected inferior vena cava (IVC). A large medial opening in the lower PTFE graft is anastomosed to an atriotomy. These two PTFE tubes are anastomosed with a pericardial patch interposed between them. During the later interventional Fontan procedure, this pericardial patch is perforated using radiofrequency, and a covered stent is positioned entirely within the PTFE tubes, eliminating the window into the common atrium and leaving no intrapulmonary prosthetic material.

Evaluation:

The hemodynamics after the preparatory stage is similar to those following a BCPC, with uninterrupted flow from the IVC to the right atrium. On completion, there is a nonfenestrated Fontan circuit.

Conclusion:

Our technique of interventional Fontan, anatomically and hemodynamically, mimics a standard ECF procedure.

The Hemi-Fontan operation: A critical overview

The hemi-Fontan (HF) operation is a staging procedure in the journey towards an ultimate Fontan palliation. Although popular in the Western world, it has found limited application in the developing world. In this review we discuss the indications, techniques, merits, and demerits of this procedure along with its present day role in developing world where there is lack of awareness about this operation.

Alternate method for hybrid Fontan completion

A Fontan completion with a hybrid approach was performed on a 27-month-old girl with a univentricular heart. A large covered stent was placed between the inferior vena cava and the cavopulmonary anastomosis through a pericardial patch in the intracardiac fenestrated tunnel, circumventing the need for an occluder device for baffle closure. The child's progress has been good and she displays normal growth and acceptable clinical, ultrasonographic, and laboratory results.

Four decades of Fontan palliation

The Fontan palliation was introduced in 1968 to treat cardiac malformations unsuitable for biventricular repair. This procedure has transformed the surgical management of congenital heart disease. In this Review, we reflect on the outcomes and clinical problems associated with this unique circulation after more than 40 years of experience. We also summarize the evolution of the Fontan procedure, highlight the long-term clinical issues and their management, and consider future expectations of a circulation driven by a single ventricle with the systemic and pulmonary blood flow in series rather than in parallel.

Evolution of the Fontan-Kreutzer procedure

The surgical techniques used to construct the Fontan-Kreutzer circulation have evolved considerably since the initial reports. In the early years, it was thought that a power source other than the main ventricular chamber was useful or even necessary to serve the pulmonary circulation. Better understanding of the physiology of the Fontan-Kreutzer circulation has led to an understanding that avoidance of flow disturbances and energy losses in the surgically constructed pathways is critically important. In vitro studies and clinical investigations of flow dynamics led to the introduction of the total cavopulmonary connection, or total cavopulmonary connections, designed to minimize flow disturbances and the resultant energy losses. Other important surgical modifications include staging with a superior cavopulmonary connection and creation of a fenestration. These innovations have resulted in extension of the Fontan-Kreutzer procedure to the management of complex univentricular hearts and, in particular, the management of hypoplastic left heart syndrome. There have been significant improvements of early mortality and morbidity following the Fontan-Kreutzer procedure. Yet it is important to recognize that there is continuing late attrition and morbidity for patients with the Fontan-Kreutzer circulation.