Utility of the Medtronic microvascular plug™ as a transcatheter implantable and explantable pulmonary artery flow restrictor in a swine model

Abstract

Background A surgical pulmonary artery band (PAB) is used to control excessive pulmonary blood flow for certain congenital heart diseases. Previous attempts have been made to develop a transcatheter, implantable pulmonary flow restrictor (PFR) without great success. We modified a microvascular plug (MVP) to be used as a PFR. The objectives of this study were to demonstrate feasibility of transcatheter implantation and retrieval of the modified MVP as a PFR, and compare PA growth while using the PFR versus PAB. Methods and results The PFR was implanted in eight newborn piglets in bilateral branch pulmonary arteries (PAs). Immediately post‐PFR implantation, the right ventricular systolic pressure increased from a median of 20–51 mmHg. Transcatheter retrieval of PFR was 100% successful at 3, 6, and 9 weeks and 50% at 12‐weeks post‐implant. A left PAB was placed via thoracotomy in four other newborn piglets. Debanding was performed 6‐weeks later via balloon angioplasty. On follow‐up, the proximal left PA diameters in the PFR and the PAB groups were similar (median 8 vs. 7.1 mm; p = 0.11); albeit the surgical band sites required repeat balloon angioplasty secondary to recurrent stenosis. By histopathology, there was grade II vessel injury in two pigs immediately post‐retrieval of PFR that healed by 12 weeks. Conclusions Transcatheter implantation and retrieval of the MVP as a PFR is feasible. PA growth is comparable to surgical PAB, which is likely to require reinterventions. The use of the MVP as a PFR in humans has to be trialed before recommending its routine use.

Hypoplastic Left Heart Stage I

“…Spontaneously breathing, sedated newborns received an endoluminal pulmonary artery (PA) branch banding with US Food and Drug Administration–approved, CE-marked Medtronic Micro Vascular Plug (MVP) devices, manually modified to a pulmonary flow restrictor (PFR), as previously described. 3 After bilateral PFR placement, the arterial duct was stented, as is routine in the Giessen hybrid approach. 4 Briefly, after local anesthesia, the femoral vein and artery were punctured, and 4F sheaths were placed.…”

Hypoplastic Left Heart: Stage-I Will be Performed Interventionally, Soon

“…Four patients have successfully completed comprehensive stage-II and one infant an uneventful bi-ventricular repair [ 39 ]. Based on sophisticated animal studies [ 40 ], pulmonary artery flow restrictors (PFRs) were manually created using CE-marked Micro Vascular Plug devices (MVP-5Q, 7Q or 9Q, Medtronic™) with sizes originally intended to accommodate vessels up to 5, 7 or 9 mm diameter (Fig. 2 a, b).…”

Total Transcatheter Stage 1: A Word of Caution

“…One patient with hypoplastic left heart syndrome, intact atrial septum and total anomalous pulmonary venous return initially underwent stenting of an obstructed vertical vein immediately after birth followed by stenting of the atrial septum at 3 days of life, with percutaneous modified stage 1 at 2 weeks of life. The modification of the MVPs for the initial case was performed by excision of the Polytetrafluoroethylene (PTFE) membrane using a scalpel as described previously [1,4]. This presented some challenges due to difficulty in stabilizing a soft device and accurately creating consistently sized defects.…”

“…This concept can potentially be applied to any lesion in which control of pulmonary blood flow is needed. Following the report by Khan et al [4] using modified Microvascular plugs (MVP) (Medtronic Inc., Minneapolis, MN) as flow restrictors, our group also applied this technique to a small series of patients and we would like to report our case series as a word of caution prior to widespread application of this technology.…”