Abstract 4555: Impact of Mechanical Distortion on Homograft Valve Competence One Year after Insertion into Pulmonary Position: a Magnetic Resonance Imaging Study
Background: Homograft valves (HV) are commonly used to restore pulmonary valve competence in congenital heart surgery. Recently, percutaneous pulmonary valve implantation (PPVI) was introduced as an alternative to repeat surgical pulmonary valve replacement (PVR). We sought to evaluate homograft competence at one year follow-up and compare it to PPVI.
Methods: 60 HV patients (mean age 21±10 years) and 66 PPVI patients (mean age 23±11 years) were assessed with echocardiography and cardiac magnetic resonance imaging (CMR) during protocolized follow-up. 2/66 (3%) PPVI patients were excluded due to an episode of endocarditis. The primary endpoint was significant pulmonary regurgitation (PR) at one year, defined as a pulmonary regurgitation fraction >20% on CMR. For the HV group, homograft-related variables (i.e. data from homograft bank) and surgery-related variables were reviewed. Furthermore, indicators of homograft geometry were studied on CMR, which involved the assessment of dimensions, inlet-to-outlet angles and pulmonary flow pattern. To study the impact of these variables on the primary endpoint, a multivariate linear regression analysis was performed.
Results: 10/60 (17%) HV patients and none of the PPVI group had significant PR (P <0.001). Two geometrical factors were strongly associated with a higher risk of significant PR in the HV group: greater homograft inlet-to-outlet angle in a sagittal plane and eccentric pulmonary forward flow (P<0.001), both suggesting mechanical distortion. Homograft- and surgery-related variables did not significantly influence the primary endpoint. 7/10 (70%) patients with significant PR at one year already showed ≥mild PR on post-operative echocardiography, emphasizing a likely role of mechanical distortion in early homograft incompetence. During follow-up, 2/10 patients underwent redo PVR (1 homograft, 1 Hancock conduit), 1/10 patient underwent PPVI and 7/10 patients are under medical follow-up.
Conclusions: Significant PR is frequent in patients one year after homograft insertion. This valve incompetence is most likely due to distortion of the homograft, suggesting that a strong circular support - as seen in PPVI - may be needed to effectively restore valvar competence in patients requiring PVR.