Abstract
Summary
We present two cases of right coronary artery occlusion in which MGuard® stent implantation failed for different causes, leading to a retrieval procedure adapted to the situation. Complete retrieval was possible in both cases. These cases illustrate the need for careful selection of the lesions that are going to be treated with this type of stent, for which pre-dilatation is recommended in severe lesions located just after an acute vessel angle, the evaluation of proximal angulation and calcification, as well as strategies for complete retrieval in case of implantation failure.
1
Introduction
The MGuard Stent (MGS) (Inspire MD, Ltd., Tel Aviv, Israel) is a conventional bare metal stent covered by a thin polymer mesh on its external surface, designed to trap the clot between the stent and vessel wall. The MGuard Prime Stent (MGS) consists of a bare metal stent platform made of a cobalt chromium alloy with a micronet sleeve coating attached to its outer surface. This is weaved with a unique thread of PET (polyethylene terephthalate) with a fiber width of 20 μm. Both components are firmly bound on their distal ends, and are assembled on a semicompliant coronary angioplasty balloon. The aperture size is 150 × 180 μm. Due to its reduced size, it acts as a retaining filter for potential clots and plaque debris that could become detached when implanting the device.
The strut thickness is 80 μm and the crossing profile is 1.0 mm (from 2.75 to 3.0 mm) and 1.2 mm (from 3.25 to 4.00 mm). The MGS device is compatible with 6-French guiding catheters and 0.014-inch guidewires. The aim is to avoid embolization of the clot and its consequences, such as reduced TIMI flow and several situations ranging from a slight coronary flow reduction to a severe myocardial blush impairment. It has been used primarily in acute myocardial infarction for the treatment of unstable plaques associated with blood clotting, particularly in acute myocardial infarction , but also in saphenous vein graft , acute intrastent thrombosis and even in the treatment of coronary perforations . Nevertheless, there are limitations in the navigability of the MGS, due to its design consisting of a polymer layer or membrane fused to the outer surface. When a clot is formed beyond severe lesions or in very tortuous coronary arteries, the delivery and navigability capacities of this stent are compromised. We present two cases in which the MGS could not cross the lesion and, in the attempt to withdraw it, was trapped in the coronary artery (both the stent and the mesh). The device could be retrieved in both cases. We describe the strategies that can be used and considerations regarding the selection of appropriate lesions and the adequate methodology for the use of the MGS.
1.1
Presentation of case 1
Male, 79 years of age with diabetes, hypertension and hyperlipidemia, presented due to ST elevation myocardial infarction (STEMI) of three hours duration. Angiography was performed, revealing right coronary artery (RCA) occlusion ( Fig. 1 A ). After the guide catheter was introduced (AR2 guide catheter: Launcher®; Medtronic, Inc. Minneapolis, MN, USA), a critical lesion was observed with a long clot behind it ( Fig. 1 B). We decided to place an MG 3–28 stent, without pre-dilation to avoid dislodging the clot. After several attempts, the MGS could not be traversed and the decision to pre-dilate the lesion was taken. On withdrawal, the MGS was trapped in the RCA ( Fig. 1 C). A 4-mm Amplatz GooseNeck® snare kit (ev3 Endovascular, Inc. Plymouth, MN, USA) was used to catch the MGS and to retrieve it with the guide catheter ( Fig. 1 D-E). Finally, the lesion was dilated with a 2 × 15 balloon catheter and a PRO-Kinetic® 3–26 stent (Biotronik AG; Bülach, Switzerland) was implanted. A satisfactory result was achieved with TIMI III flow ( Fig. 1 F).
1.2
Presentation of case 2
Male, 76 years of age, ex-smoker with hypertension and hyperlipemia presented in the emergency room with STEMI of 2 hours duration. RCA occlusion was detected on angiography. After introduction of the guidewire, the lesion was observed to be severe, associated with a clot after the lesion and the acute marginal branch ( Fig. 1 A and B). An AR2 guide catheter (Launcher®; Medtronic, Inc. Minneapolis, MN, USA) was used, but the characteristics of the exit of the RCA ostium did not provide good support, so a GuideLiner® catheter (Vascular Solutions, Inc. Minneapolis, MN, USA) was used to place an MGS 3–18 ( Fig. 3 C and D ). Despite this extra support, the MGS could not cross the lesion, so it was withdrawn via the catheter and the guide catheter. In the maneuver, the stent and the mesh were trapped in the RCA just before the lesion ( Fig. 3 E). A Coroflex® 2.75–13 stent (B. Braun Melsungen AG, Berlin, Germany) was then selected, which crossed the stent and the MGS mesh from a coaxial approach. After successful implantation, the balloon of the already placed stent was inflated again and pulled back, leading to the successful retrieval of the MGS and the mesh ( Fig. 3 ). The patient’s result was good with TIMI III flow ( Fig. 2 F).
