Impact of percutaneous pulmonary valve implantation procedural steps on leaflets histology and mechanical behaviour: An in vitro study
Résumé
Background: Percutaneous pulmonary valve implantation (PPVI) using bovine jugular vein
Melody valve is safe and effective. However, post-procedural complications have been
reported for unclear reasons.
Objective: We sought to assess the impact of PPVI procedural steps on valvular histology
and leaflet mechanical behaviour.
Methods: Three different valved stents (Melody valve, homemade stents with bovine and
porcine pericardium) were tested in-vitro in 4 conditions: I) control group, II) crimping, III)
crimping + inflation of low-pressure balloon and IV) condition III + post dilatation (highpressure
balloon). For each condition, valvular leaflets (and venous wall sample for Melody
stents) were taken for histological analysis and mechanical uniaxial tests of valve leaflets.
Results: Among Melody valves, incidence of transverse fractures was significantly higher in
traumatized samples compared with control group (p<0.05) whereas, incidence and depth of
transverse fractures were not statistically different between the 4 conditions for bovine and
porcine pericardial leaflets. No significant modification in mechanical behaviour of in-vitro
traumatized Melody® valvular leaflets was observed. Bovine and porcine pericardia became
more elastic and less resilient after balloon expansion and post-dilatation (condition III and
IV), with a significant decrease of elastic modulus and stress at rupture.
Conclusion: Valved stent implantation procedural steps induce histological lesions on
Melody valve leaflets. Conversely, bovine and porcine pericardial valved stents were not
histologically altered by in vitro manipulations although their mechanical properties were
significantly modified. These data could explain some of the long-term complications
observed with these substitutes.
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