Summary
Background
Fontan circulation is fragile and unfavourable evolution is frequent. Fontan physiology largely depends on respiration and gravity. The hypothesis for valvulation is that valvulation of the circuit reduces the effects of respiration and the proclive position, and increases anterograde flow towards the systemic circulation, with increasing exercise capacity and benefits for enteropathy. Because it originates from the bovine jugular vein, the Melody ® valve (Medtronic, Minneapolis, MN, USA) is naturally designed to work in a low-pressure environment.
Aims
To report our experience of percutaneous valvulation of refractory failing Fontan circulation.
Methods
We reviewed all patients who received a Melody valve in Fontan circulation in our unit.
Results
Four patients were included: two had severe and refractory protein-losing enteropathy; one had severe oedema and ascites; and one had very severe lower limb venous insufficiency. The Melody valve was successfully implanted in all patients. Central venous pressure and inferior vena cava pressure did not change after valvulation. There were no early complications. At follow-up, no acute or mid-term thrombosis was noted. Two patients had intracardiac echocardiography 6 and 24 months after valvulation: the Melody valve was found not to be functioning in both cases. One patient died 3 months after valvulation; the cause was unrelated to the procedure.
Conclusion
Percutaneous valvulation of Fontan circulation is technically feasible. More clinical studies are needed before considering this treatment as an option.
Résumé
Contexte
La circulation de Fontan est fragile avec une évolution emaillée de nombreuses complications. Sa physiologie est unique et dépend beaucoup de la respiration et de la gravité. L’hypothèse de l’effet favorable de la valvulation est que la mise en place d’une valve dans le circuit réduit les effets de la respiration et de la position proclive. Ce faisant, la valvulation augmente le débit antérograde de la circulation systémique améliorant la capacité à l’effort et peut également diminuer les signes d’entéropathie exsudative. La valve Mélody ® (Medtronic, Minneapolis, MN, États-Unis) qui est issue de la jugulaire de bœuf est, de par son origine, naturellement faite pour fonctionner dans un environnement à basse pression.
Objectif
Nous rapportons notre expérience de la valulation percutanée de circuits de Fontan défaillants et réfractaires au traitement médical conventionnel.
Méthodes
Tous les patients ayant reçu une valve Mélody dans une circulation de Fontan ont été revus.
Résultats
Quatre patients ont été inclus : deux patients avaient une entéropathie exsudative sévère et réfractaire aux traitements conventionnels ; un patient était en anasarque avec une ascite importante ; et le dernier présentait de très larges varices invalidantes des members inférieurs. La Mélody a été implantée chez les quatre patients avec succès. Les pressions veineuses centrales et caves inférieures n’ont pas été modifiées par la valvulation. Il n’y a pas eu de complications précoces ni tardives. Durant le suivi, il n’y a pas eu de thrombose aiguë ou chronique démontrée. Deux patients ont eu une échographie intracardiaque respectivement à 6 et 24 mois après valvulation : il n’y avait pas de fonction valvulaire observée. Un patient est décédé 3 mois après la procédure sans relation avec celle-ci.
Conclusions
La valvulation percutanée est aisément réalisable. D’autres études cliniques sont nécéssaires avant de considérer ce traitement comme option thérapeutique en cas de défaillance de circulation de Fontan.
Background
The Fontan procedure provides good palliation for patients with single ventricular physiology . However, this non-physiological circulation is fragile, and many patients will experience a variety of end-organ complications and unique morbidities . Complications are varied and can be unspecific, such as ventricular dysfunction, arrhythmias and global cardiac failure, or more specific to the failing Fontan, such as liver fibrosis, protein-losing enteropathy (PLE) and plastic bronchitis. These complications are the consequences of a complex physiology involving circulatory insufficiency, inflammation and lymphatic derangement . Management strategies are emerging, but current treatments are usually palliative, with modest results, and once severe complications occur, life expectancy is shortened . Heart transplantation is the only treatment, but is technically challenging and the outcome is poorer than in other diseases requiring heart transplantation .
The use of stents in Fontan circuits has been reported in various situations, with good results; they have been placed in pulmonary arteries to relieve stenosis and in the extracardiac conduit to treat acute thrombosis . Recently, we reported the use of a covered stent to close fenestration, with a good result and no thromboembolic complications .
Fontan physiology is unique. Cardiac output in this setting is almost exclusively preload dependent and varies with gravity and respiration . Part of the inferior vena cava (IVC) blood flows back into the abdominal compartment during expiration. The importance of respiration in the Fontan circulation has been evaluated in in vitro experimental models, but also by computational fluid dynamic studies . This phenomenon is emphasized in the proclive position; decrease of cardiac output is noticed in this position and might be responsible for decreased exercise capacity, liver cirrhosis and PLE . We and others have hypothesized that valvulation of the Fontan pathway reduces respiratory variations and decreases the effects of gravity and the proclive position. As a result, valvulation theoretically increases preload and cardiac output, and might improve exercise capacity and decrease PLE. This hypothesis is also supported by recent mathematical and in vitro studies .
There is long-term experience of valved Fontan in the initial period, showing poor results, related to early stenotic degeneration of the surgically implanted valve. Two recent changes made us resuscitate this option: availability of transcatheter valved stents; and a potentially good substitute – the Melody ® valve (Medtronic, Minneapolis, MN, USA). In the early days, valvulation was done using an aortic valve (mostly human or porcine); because of their origins, these valves are thick and are designed to work at high pressures. The Melody valve is a bovine jugular vein sutured in a stent; this valve is thin and is designed to work in a low-pressure environment.
Because of the lack of therapeutic options, we sought to offer alternative palliation for patients with failing Fontan despite maximal medical treatment. Percutaneous valvulation of the Fontan circuit was offered to these patients, using a Melody valve. To date, this is the first report on percutaneous valve implantation in a Fontan circulation. We review the results of percutaneous valvulation of Fontan circuit and report on the acute and chronic effects of this procedure.
Methods
Patients who received a Melody valve in a failing Fontan circulation were reviewed in our institution. The patients had various complications related to the Fontan circulation despite maximal medical treatment. Exclusion criteria were anatomical abnormalities responsible for Fontan dysfunction and contraindication to anticoagulation or antiplatelet therapy.
All patients presented with severe symptoms of Fontan failure; they were all on maximal medical treatment and were aware of the lack of other therapeutic options. The cardiologist in charge of the patient explained the technical details of the valvulation and the potential benefits of the procedure to the patient and their family. The absence of medical data regarding percutaneous valvulation in this setting was also mentioned to the patient. Informed consent was obtained from each patient.
Because of their heterogeneity and number, patients are presented as individual cases. Data on patient characteristics, surgical history and clinical status before and after implantation are provided for each patient.
Results
Four patients had a Melody valve implanted in a failing Fontan; they all presented with a severe medical condition secondary to a failing Fontan circulation despite maximal medical treatment. All valves were implanted from the femoral vein. Results are summarized in Tables 1, 2 and 3 .
| Patient 1 | Patient 2 | Patient 3 | Patient 4 | |
|---|---|---|---|---|
| Age (years) | 29 | 14 | 21 | 25 |
| CHD | Tricuspid atresia | Complex DORV | PA-IVS | PA-IVS |
| Palliation | Fenestrated extracardiac Fontan | Extracardiac Fontan | Fenestrated extracardiac Fontan | Classical Fontan |
| NYHA | III | II–III | III | II |
| Complications | PLE, liver fibrosis | PLE | Oedema, ascites | Lower limb venous insufficiency |
| Patient 1 | Patient 2 | Patient 3 | Patient 4 | |
|---|---|---|---|---|
| Baseline (mmHg) | ||||
| CVP | 14 | 17 | 14 | 15 |
| Wedge pressure | 10 | 12 | 10 | 10 |
| Post-valvulation (mmHg) | ||||
| CVP | 14 | 17 | 19 | 15 |
| Patient 1 | Patient 2 | Patient 3 | Patient 4 | |
|---|---|---|---|---|
| Follow-up (months) | 28 | 3 a | 28 | 24 |
| Clinical status | No PLE | Transient improvement | Stable | Stable |
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