Summary
Background
Owing to the wide variety of surgical substrates used for right ventricular outflow tract (RVOT) reconstruction, the predictors of successful outcomes in such patients are unclear.
Aims
To compare haemodynamic outcomes of percutaneous pulmonary valve implantation (PPVI) in patients with dysfunctional RVOT.
Methods
This was a multicentre prospective study on all consecutive patients who underwent PPVI from May 2008 to December 2009. All patients underwent prestenting using a bare-metal stent. The patients were divided into two groups based on the surgical substrate used for RVOT reconstruction.
Results
Baseline demographics, including right ventricle to pulmonary artery (RV-PA) pressure gradient and RV/aortic (Ao) pressure ratio, were similar in both groups. The mean RV-PA gradient and RV/Ao pressure ratio showed immediate and significant improvement after PPVI. At last follow-up, the RV-PA gradient and RV/Ao pressure ratio were significantly higher in patients with non-expandable conduits ( P = 0.002 and P = 0.008, respectively). Patients with conduits greater than 20 mm showed better immediate and midterm outcomes compared with other patients. Patients with non-expandable conduits less or equal to 20 mm diameter showed good immediate outcomes but poor midterm haemodynamic outcomes compared with those with expandable conduits less or equal to 20 mm diameter ( P = 0.03).
Conclusions
PPVI is successful with a wide variety of surgical substrates used for RVOT reconstruction; there was immediate haemodynamic improvement in all patients. However, patients with non-expandable conduits less or equal to 20 mm had the worst outcomes. This information should be integrated into the decision-making process before selecting patients for PPVI.
Résumé
Contexte
Il existe une grande variété de conduits chirurgicaux utilisés pour reconstruire la voie d’éjection droite. Lorsqu’ils sont potentiellement candidats à la mise en place d’une valve par voie percutanée, les facteurs prédictifs de succès ne sont aujourd’hui pas clairs.
Objectifs
Le but de l’étude est de comparer les résultats hémodynamiques après valvulation endovasculaire pulmonaire en fonction du type de conduits prothétiques.
Méthodes
Il s’agit d’une étude multicentrique, prospective regroupant tous les patients inclus consécutivement entre mai 2008 et décembre 2009. Tous les patients ont eu un pré- stenting avant la mise en place de la valve par voie percutanée. Les patients ont été divisés en deux groupes selon le type de conduit chirurgical mis en place pour reconstruire la voie d’éjection droite.
Résultats
L’hémodynamique de base comprenant le gradient entre le ventricule droit et l’artère pulmonaire, le rapport pression ventriculaire droite sur pression aortique systolique, était similaire dans les deux groupes. Après valvulation, il y avait une amélioration immédiate de ces paramètres. Au dernier suivi, le gradient entre le ventricule droit et l’artère pulmonaire, le rapport pression ventriculaire droite sur pression aortique systolique étaient significativement plus élevés chez les patients ayant des conduits non dilatables ( p = 0,002 et p = 0,008, respectivement). Les patients avec un conduit de diameter nominal supérieur à 20 mm avaient un meilleur devenir à court et moyen terme par rapport aux autres. Les patients avec un conduit non expansible de moins de 20 mm avaient un bon devenir à court terme mais un résultat hémodynamique médiocre à moyen terme lorsqu’ils étaient comparés aux patients avec des conduits expansibles de moins de 20 mm ( p = 0,03).
Conclusions
Le remplacement valvulaire percutané est efficace chez des patients ayant eu une reconstruction de la voie d’éjection droite avec une grande variété de conduits chirurgicaux. Il était noté une amélioration de l’hémodynamique immédiate chez tous les patients quel que soit le type de conduit chirurgical en place. Cependant, les patients avec des conduits non expansibles de moins de 20 mm avaient des résultats médiocres à moyen terme. Cette information doit être intégrée dans la prise de decision lors de la selection des patients pour une implantation percutanée d’une valve pulmonaire.
Background
Percutaneous pulmonary valve replacement using the transcatheter technique has been widely accepted and practiced worldwide. The device (Melody ® Transcatheter Pulmonary Valve; Medtronic Inc., Minneapolis, MN, USA) is available in a single diameter of 18 mm, dilatable up to 22 mm. The indications are currently limited to patients with dysfunctional right ventricular outflow tract (RVOT) homografts or prosthetic conduits with a diameter that does not exceed 22 mm at the time of implantation . Surgical techniques to maintain right ventricle to pulmonary artery (RV-PA) continuity can be achieved by modification of RVOT or reconstruction using a variety of biological or synthetic tubes; these are available in various sizes as expandable or non-expandable conduits. Owing to wide variations in the surgical substrates used for RVOT reconstruction, the outcomes after percutaneous pulmonary valve insertion (PPVI) may vary and are presently unclear. We sought to evaluate the immediate and midterm haemodynamic outcomes of PPVI in patients with expandable versus non-expandable conduits.
Methods
This is a prospective multicentre non-randomized trial to evaluate outcomes after Melody ® valve implantation in France (Y. B. principal investigator). The study received approval from the French Ministry of Health in May 2008. Patients with pulmonary regurgitation and/or stenosis were enrolled in four different centres across France (Paris, Massy, Marseille and Bordeaux). Patients with dysfunctional RVOT were identified and evaluated to assess suitability for PPVI. All patients were evaluated using a standard protocol to assess procedural success, complications, costs, safety and immediate and midterm outcomes. This is an ongoing study and the global results are still pending. We report outcomes on all patients who underwent PPVI from May 2008 to December 2009 in two centres (Centre de Reference Maladies Rares M3 C, George Pompidou European Hospital [adult unit] and Necker Hospital [children unit], Paris, France, operator Y.B.; and Timone Hospital, Marseille, operator A.F.). The study is registered at the National Institute of Health website (www.clinicaltrials.gov) as identifier NCT01250327 .
Preprocedure evaluation
All patients underwent a preinclusion clinical evaluation, including electrocardiography, echocardiography, exercise testing, computed tomography scan and magnetic resonance imaging. Qualifying patients had varying RVOT lesion characteristics, such as pulmonary obstruction, pulmonary regurgitation and mixed lesions . Patients with obstruction or mixed lesions were included in this study. Medical charts were reviewed to assess the details of the RV-PA conduit. The study population was divided into two groups with respect to the expandable characteristics of the initial conduit: group I consisted of patients with expandable conduits; group II consisted of patients with non-expandable prosthetic conduits ( Fig. 1 and Table 1 ). The grouping was performed by two authors blinded to the outcome. The classification was made based on the intrinsic properties of the initial conduit and not on the properties after in vivo exposure; therefore, features such as calcifications, external compressions, etc. were not taken into account for classifications.
| Expandable | Non-expandable |
|---|---|
| Native RVOT enlarged with a patch | Synthetic non-expandable conduits |
| Native RVOT enlarged with a Monocusp | Dacron valved conduits |
| Synthetic expandable conduits (Contegra) | Hancock conduits |
| Homograft | Carpentier-Edwards conduits |
Cardiac catheterization and sizing of the RVOT
All patients underwent cardiac catheterization using general anaesthesia or deep sedation with or without endotracheal ventilation. A preprocedure detailed haemodynamic assessment was done in all patients, with assessment of mean right atrial, RV (systolic, early and end-diastolic), PA and aortic (Ao) pressures (systolic, diastolic and mean). The peak-to-peak RV-PA gradient was calculated as the difference in systolic pressure between the RV chamber and the main PA. If the RV/Ao systolic pressure ratio was greater than 0.66, stenosis was the primary indication. If the RV/Ao systolic pressure ratio was less than 0.25 in the presence of pulmonary regurgitation, pulmonary regurgitation was considered the primary lesion. The remainder were categorized as mixed lesions. Patients with regurgitation as the primary lesion were excluded from this study. RVOT and aortic root angiograms were performed in two views (lateral and four-chamber) in all patients. Ao angiography was performed to assess the proximity of the Melody ® valve landing zone to the coronary arteries.
Preparation for Melody ® valve insertion
All patients had prestenting of the RVOT using single or multiple bare-metal stents (BMSs) (CP, [NuMED, Hopkinton, NY, USA] or Max LD [EV3, Plymouth, MN, USA]).
Melody ® valve insertion
The Melody ® valve (Model PB10) was inserted using the 22-mm Ensemble ® transcatheter valve delivery system (NU10) (Medtronic Inc., Minneapolis, MN, USA). All patients underwent RVOT predilatation with a balloon of appropriate diameter (ATLAS ® or Mullins PTA Dilatation Balloon; Bard Peripheral Vascular, Inc., Tempe, AZ, USA) before Melody ® valve implantation. The diameter of the balloon was equal to the nominal conduit size (maximum diameter 22 mm). Balloons were inflated to the burst pressure indicated on the manufacturer’s label, regardless of the grouping. In patients with no circumferential conduit (patch enlargement), a PTA Dilatation Balloon 22 mm in diameter was used. Postdilatation was achieved using a high-pressure balloon in all patients, with the aim of decreasing the RVOT gradient as much as possible. Therefore, overexpansion above the nominal conduit size was performed when needed. Haemodynamic and angiographic assessments were repeated after PPVI in all patients. All patients received heparin and antibiotic prophylaxis during and after the procedure, according to institutional protocol, and were discharged on aspirin 100 mg/day orally.
Follow-up
All patients were scheduled for an office visit at 1, 3, 6, 12 and 24 months following valve implantation. A repeat transthoracic echocardiogram was performed during every follow-up. All events were recorded in a large institutional review board-approved database.
Statistical analysis
PASW Statistics version 17.0 (SPSS, Inc., Chicago, IL, USA) was used for statistical analysis. Nominal variables are expressed as numbers and percentages and were compared using Fisher’s exact test or the chi-square test, as appropriate. Ordinal variables are presented as means ± standard deviations and were compared using the Wilcoxon rank sum test. Continuous variables are expressed as means ± standard deviations and were compared using the independent variables t test. All tests were two-sided and a P value < 0.05 was considered statistically significant.
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