Outcomes of Modified Microvascular Plugs as a Pulmonary Flow Restrictors in Congenital Heart Disease.

Manually modified microvascular plugs (M-MVPs) have emerged as transcatheter pulmonary flow restrictors (PFRs) in neonates and infants with complex congenital heart disease and pulmonary overcirculation. Standardized device modification methods and short-term outcomes remain limited. We performed a retrospective single-center clinical data review of consecutive patients who underwent transcatheter pulmonary flow restriction using M-MVPs from January 2023 through June 2025. Data collected included patient characteristics, procedural details, peri-procedural complications, surgical outcomes, device explantation, and mortality. Twenty-one neonates and infants (median age: 16 days (IQR 8-22); median weight: 2.8 kg (IQR 2.3-3.9) received 44 M-MVP devices. Femoral venous access was used in 20/21 cases, with carotid access required in one patient. Median angiographic branch pulmonary artery diameters were 5.1 mm (left) and 5.3 mm (right). Fifteen patients underwent surgical explantation at a median 43 days (IQR 37.5-58.5 days), with one patient supported for 236 days. All devices were surgically explanted without major intraoperative complications or device related stenosis requiring pulmonary arterioplasty. Three patients required additional device implantation for distal migration or incomplete pulmonary artery coverage, and two patients ultimately required conversion to surgical main pulmonary artery banding. Interval mortality was 29% (6/21) in a cohort with substantial comorbidity, physiologic instability, and limited surgical candidacy. Exploratory physiologic analysis demonstrated higher renal near-infrared spectroscopy values among patients who survived to surgery, although physiologic responses following implantation were variable. In this retrospective descriptive experience, M-MVPs provided technically feasible temporary pulmonary flow restriction in carefully selected high-risk neonates and infants. Given the small sample size, heterogeneous cohort, and lack of a control group, the findings presented should be considered descriptive and hypothesis generating.