Coils and plugs have emerged as the most commonly employed mechanical embolic devices. Various coils are used in daily practice for an array of clinical applications. Although effective, the main disadvantage of coils relates to the number of coils and time needed to achieve adequate vascular occlusion. Additional limitations of traditional pushable coils include lack of controlled deployment, occlusion of nontarget vessels secondary to coil migration, incomplete occlusion, and recanalization.

More recently, vascular plugs have been shown to be a viable alternative to conventional coil embolization. Advances in technology have led to the widespread availability of plugs in a variety of lengths and sizes and have helped overcome the access and time limitations of conventional coils. The Amplatzer Vascular Plug 4 (St. Jude Medical, Inc.) is available in 4- to 8-mm diameters and allows for the occlusion of arteries from 2.6- to 6.2-mm. Although it is an effective embolic device, its primary shortcoming is that it still requires a 4- or 5-F catheter (0.038-inch inner-diameter lumen) for delivery and does not result in immediate occlusion. This precludes its utilization in a significant number of embolization procedures in which smaller-caliber vessels necessitate a microcatheter or if a more rapid occlusion is desired.

The newly developed, CE Mark- and US Food and Drug Administration-cleared state-of-the-art MVP™ micro vascular plug system (Medtronic) addresses the drawbacks of its predecessors. The MVP™ plug, composed of nitinol and covered by a polytetrafluoroethylene (PTFE) membrane at the proximal end and approximately two-thirds of its length, is designed for rapid vascular occlusion (Figure 1). Passing through standard microcatheters, the MVP™ plug can navigate through torturous vessels as small as 1.5 to 3 mm in diameter, providing super-selective access and embolization. The MVP™ plug is a detachable and resheathable device, which allows for controlled, precise deployment with stability. Finally, the device allows for angiography to be performed through the microcatheter with the MVP™ plug in place before deployment, which enables additional safety and unparalleled accuracy.

TECHNICAL DETAILS AND CLINICAL BENEFITS

The MVP™ plug is currently available in two sizes: (1) The MVP-3 plug has an unconstrained diameter of 5.3 mm for target vessels in a 1.5- to 3-mm-diameter range; (2) the MVP-5 plug has an unconstrained diameter of 6.5 mm for target vessels in a 3- to 5-mm-diameter range. The MVP-3 and MVP-5 plugs are designed for delivery via 0.021-inch and 0.027-inch inner-diameter microcatheters, respectively (Table 1).

The length of the unconstrained MVP™ plug is 12 mm, which may increase up to about 15 mm when deployed in the vessels in target diameter range; therefore, a landing zone length of ≥ 15 mm is recommended to accommodate the device without inadvertently occluding unintended vessels. The manufacturer advises against placing the device at the curve of a vessel; however, we have landed the device in such a location in several cases with stability of the device and no complications.

The MVP™ plug boasts an array of established clinically relevant device features. The MVP™ plug holds the advantage of being a single all-inclusive device capable of vascular embolization, differentiating it from coils and other plugs, which require multiple devices and/ or time to achieve vessel occlusion. The MVP™ system is compatible with any 0.021- or 0.027-inch microcatheter (≤ 155 cm) currently available on the market. This feature allows for unparalleled navigability, allowing the MVP™ system to be delivered to distal targets, even in the face of challenging tortuous anatomy. We have tracked the MVP™ plug across 360° turns in arteries with ease.

Microcatheter delivery also allows for predetachment angiography to ascertain efficacy and location. The value of the ability to inject contrast through the microcatheter with the MVP™ plug in place cannot be overstated, because this is not feasible with coils. This unique feature allows for the operator to have greater confidence in placement and allows manipulation, if necessary, before final deployment.

The device’s unique resheathability features allow it to be completely resheathed and redeployed without disruption, serving to ensure optimal and precise arterial occlusion. The ability to reliably place, reposition, and perform angiography before deployment provides vast benefits in difficult cases, especially when encountering precarious anatomy or high-flow vascular beds.

CLINICAL DATA

The device has been proven to be extremely efficacious, as it provides consistent, immediate, and stable target vessel occlusion from a single implant. The ability to produce immediate results is critical; other devices may require 20 minutes or longer to achieve complete occlusion. The MVP™ delivery system has been shown to reliably produce stable results. A clinical study by Pellerin et al demonstrated immediate occlusion in all treated vessels with no displacement or migration of the plug after successful implantation.1 The MVP™ plug was resheathed, relocated, and redeployed in 30% of cases in this study without any issue.

Migration is a concern after coil embolization. This complication is minimized with the MVP™ plug, given the oversizing recommended by the manufacturer as well as the greater surface area of the device in contact with the vessel wall. Vascular recanalization after coiling is a well-known problem (Case 2). Although there is no systematically collected prospective data with regard to recanalization rates with the MVP™ plug, we hypothesize that vascular recanalization would be virtually eliminated given the circumferential PTFE covering of the device.

COST-EFFECTIVENESS

There are no studies specifically evaluating the cost effectiveness of the MVP™ plug compared to pushable and detachable coils. Its value in an assortment of clinical applications as a stand-alone embolic device underlies its potential cost-saving benefits. According to the COSY trial, an average of 3.4 0.018-inch Interlock™ coils (Boston Scientific Corporation) were required for gastroduodenal artery (GDA) embolization during a Y-90 mapping procedure.2 At a sales price of $750, this would result in a $2,550 total device cost for the embolization. A single MVP™ plug is listed at $1,750, resulting in cost savings of $800.

A prospective comparison of hydrogen-coated microcoils and fibered platinum microcoils for GDA embolization was evaluated by Maleux et al.3 Per Table 2 (please note the MVP™ device was not evaluated in this study but is included for comparison), the MVP™ device would result in significant savings over both pushable and detachable hydrogel microcoils. The MVP™ plug’s cost is comparable to fibered platinum microcoils, although only a single MVP™ device is required with immediate occlusion.

In addition to potential cost effectiveness with regards to device cost, additional savings may be realized via reduced procedure times, contrast utilization, complications, and need for reinterventions.

CLINICAL APPLICATIONS

The MVP™ plug may be used for a multitude of diverse clinical applications involving embolization of the peripheral vasculature (both arterial and venous). Selected clinical cases presented here include the following:

• GDA embolization during a yttrium-90 (Y-90) radioembolization mapping procedure (Case 1).
• Recanalized pulmonary arteriovenous malformation (AVM) that was previously treated with pushable coils (Case 2).
• Splenic artery hemorrhage secondary to tumoral erosion (Case 3).
• Lumbar artery pseudoaneurysm after cryoablation (Case 4).
• Lower gastrointestinal hemorrhage (Case 5).

Another potential application of the MVP™ plug would be temporary vessel occlusion. For example, in a patient with previous extensive gastric/duodenal surgery, permanent embolization of the GDA may put the patient at risk for ischemic complications. In such a case, an interventionist may place an MVP™ plug in the GDA (leaving it on the delivery catheter undeployed) while performing radioembolization via a second access microcatheter. The MVP™ plug may then be resheathed and removed at the completion of the case. A similar strategy may be utilized in vascular malformations and other complex vascular cases in which only temporary occlusion of a critical vessel during the procedure is desired.

CONCLUSION

The MVP™ plug represents a new paradigm in embolotherapy with its unique ability to achieve safe, effective effective, and immediate permanent vascular occlusion through a single device. The distinctive features of the device add a level of precision and efficiency currently unattainable with other devices. Dramatic decreases in occlusion time, achievable only with the MVP™ plug, leading to shorter procedure times make this an excellent tool, especially in critically ill patients.

The development of larger devices is currently underway and is poised to expand the clinical utility of the device.

Ripal T. Gandhi, MD, FSVM, is with Miami Cardiac and Vascular Institute in Miami, Florida. He has disclosed that he is a consultant to Medtronic. Dr. Gandhi may be reached at gandhi@baptisthealth.net.

Brian E. Schirf, MD, is with Riverside Radiology and Interventional Associates, Inc., in Columbus, Ohio. He has disclosed that he is a consultant to Medtronic and Cook Medical. Dr. Schirf may be reached at bschirf@riversiderad.com.

Jonathan Iglesias, MD, is with Miami Cardiac and Vascular Institute in Miami, Florida. He has disclosed that he has no financial interests related to this article.

  1. Pellerin O, Maleux G, Dean C, et al. Microvascular plug: a new embolic material for hepatic arterial skeletonization. Cardiovasc Intervent Radiol. 2014;37:1597-1601.
  2. Fischman AM, Ward TJ, Patel RS, et al. Prospective, randomized study of coil embolization versus Surefire infusion system during ytrrium-90 radioembolization with resin microspheres. J Vasc Interv Radiol. 2014;25:1709-1716.
  3. Maleux G, Deroose C, Fieuws S, et al. Prospective comparison of hydrogel-coated microcoils versus fibered platinum microcoils in the prophylactic embolization of the gastroduodenal artery before yttrium-90 radioembolization. J Vasc Interv Radiol. 2013;24:797-803.