Mitral Valve Replacement in Infants Using a 15-mm Mechanical Valve

Background: The 15-mm mechanical valve was approved by the US Food and Drug Administration in March 2018. We review our experience in infants with this valve in the mitral position (MV), focusing on outcomes and timing to repeat MV replacement (MVR). Methods: Between 2006 and 2017 7 patients underwent eight MVRs (one repeat) with a 15-mm mechanical valve. Retrospective chart review was performed to examine short- and long-term outcomes. Results: There were no operative deaths. Mean follow-up was 5.8 ± 4.8 years (range, 0.72 to 11.1). Six patients underwent an MV operation 53 ± 39 days (range, 9 to 118) before MVR with the 15-mm valve. All patients were on mechanical ventilatory support at the time of operation. Mean age, body weight, and body surface area at time of 15-mm MVR were 0.5 ± 0.3 years (range, 0.2 to 0.9), 5.6 ± 0.8 kg (range, 4.8 to 6.6), and 0.29 ± 0.03 m² (range, 0.27 to 0.32), respectively. Two patients required pacemaker implantation for atrioventricular block, both after their second MVR. Two patients are well at 16 and 24 months. Four patients underwent repeat MVR because of somatic growth and patient-prosthesis mismatch. Mean time to repeat MVR was 23 months (range, 6 to 40). There were two late deaths, one at 10 months unrelated to the valve in a child with a chromosomal abnormality. The other child had a congenital diaphragmatic hernia, early valve thrombosis, and died of multiple complications after a fourth MVR. Conclusions: The 15-mm mechanical valve was useful in treating MV disease in infants 2 to 12 months of age. This newly approved smallest available mechanical valve has a predicted mean time to replacement of 23 months in the mitral position.