Successful Aspiration of Mynx Vascular Closure Device Sealant That Embolized to the Popliteal Artery

ABSTRACT: The Mynx (AccessClosure, Inc) is a vascular closure device that uses extravascular deployment of a self-expanding polyethylene glycol (PEG) sealant delivered during removal of the procedural sheath. An intravascular balloon is inflated at the arteriotomy site to prevent leakage of the sealant into the bloodstream. The complication rate with the Mynx vascular closure device is low, but there have been reports of distal embolization of the sealant. Optimal treatment of this complication is unknown, with limited published data relating only to surgical extraction. This is the first reported case of successful percutaneous aspiration of embolized Mynx vascular sealant.

J INVASIVE CARDIOL 2013;25(8):E172-E174

Key words: Mynx vascular sealant, complications

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The desire for earlier ambulation in patients undergoing percutaneous coronary intervention (PCI) procedures via a femoral artery approach prompted the development of vascular closure devices (VCDs). One such device is the Mynx (AccessClosure, Inc), which received Food and Drug Administration approval in May 2007. The Mynx device uses extravascular deployment of a self-expanding polyethylene glycol (PEG) sealant delivered via the existing procedural sheath. An intravascular balloon is inflated at the arteriotomy site to prevent leakage of the sealant into the bloodstream. The sealant biodegrades over several weeks and the Mynx is marketed as inducing less scarring at the arteriotomy site than the Angio-Seal device (St Jude Medical, Inc). The Mynx study, a prospective, multicenter, single-arm clinical investigation conducted at five European centers, reported a very low rate (0.5%) of major vascular complications with the device.¹ However, dramatic complications, including distal intravascular embolization of the sealant with acute occlusion of the popliteal artery, have been described.²

Case Report. A 56-year-old African-American female with hypertension and ongoing tobacco use presented with a non-ST elevation myocardial infarction (NSTEMI). Coronary angiography showed a 99% stenosis of the ramus intermedius, which was treated by placement of a drug-eluting stent. An attempt was made to close the right femoral arteriotomy site with a Mynx device after confirmation of an appropriate arteriotomy location with femoral angiography (Figure 1A). The device was deployed using the manufacturer’s recommended technique, but was unsuccessful at establishing hemostasis, necessitating the use of manual pressure. 

The patient developed exertional discomfort in her right leg that was noticeable when she first ambulated after the procedure. This discomfort progressed to the point where she was having symptoms with minimal exertion. She limited her activities, but did not seek medical attention until her regularly scheduled visit with her cardiologist 4 weeks after PCI. Examination revealed no palpable pulses below her right common femoral artery, but no evidence of acute limb ischemia. A lower-extremity vascular duplex study revealed evidence of right popliteal artery occlusion. Selective angiography of the right lower-extremity arteries confirmed popliteal artery occlusion with distal reconstitution through extensive bridging collaterals (Figure 1B). 

A 90 cm 6 Fr sheath (Cook Medical) was placed in the right mid superficial femoral artery via the left femoral artery. Heparin was administered intravenously for anticoagulation. Through a 5 Fr Vertebral catheter, a Whisper 0.014˝ coronary guidewire (Abbott Vascular) was advanced through the occlusion. This resulted in partial restoration of patency. Manual aspiration attempted through the 5 Fr Vertebral catheter and a 6 Fr Multipurpose guide catheter was unsuccessful. The 90 cm sheath was then advanced into the occlusion and aspiration resulted in recovery of material resembling PEG and thrombus (Figure 1C). Subsequent angiograms revealed small filling defects in the right popliteal artery, but with significantly improved distal run-off (Figure 1D). The patient had complete resolution of right lower-extremity pain and restoration of normal dorsalis pedis and posterior tibial pulses. Four months later, she was without claudication and had normal distal pulses in the right leg.

Discussion. The current case is the first reported successful percutaneous aspiration of Mynx sealant material that embolized. The Mynx device is designed as an extravascular sealant with the delivery of PEG to the external aspect of the arteriotomy site via the tissue tract. Adequate delivery, however, requires an “advancer tube” to be used after delivery of the sealant to the arteriotomy site to ensure that the sealant remains in situ. It is conceivable that during this process, overzealous forward pressure on the advancer tube as the balloon catheter is removed may push the sealant into the artery. In a small study, Fields et al found that 5 of 27 patients (18%) had evidence of intravascular Mynx sealant on vascular imaging performed a mean 8.4 days after device deployment.³

Islam et al reported the case of a 63-year-old male who had embolization of Mynx sealant after a successful case of stent placement in the right external iliac artery.² Three days after the procedure, the patient presented with left foot pain and examination was consistent with arterial insufficiency in the left foot. Angiography using the right common femoral access showed a large filling defect in the distal left popliteal artery with extension into the tibeoperoneal trunk. The embolus did not resolve with intravenous heparin for more than 24 hours or with an intraarterial infusion of tissue plasminogen activator. During surgical exploration of the popliteal artery, three pieces of Mynx material were removed from the left popliteal, posterior tibial, and peroneal arteries. Following surgery, the patient had significantly improved pulse in the left lower extremity and no further evidence of ischemia. 

Reports of distal embolization with the Mynx device are rare and in general there are few complications reported with the device. In a study of 238 patients who received Mynx closure, the rate of major vascular complications was 2.1% and included 2 cases of retroperitoneal bleeding requiring surgical intervention, 2 cases of pseudoaneurysm requiring surgical repair, and 1 case of hemorrhage with a loss of >3 g hemoglobin.⁴ In a prospective, multicenter, single-arm clinical investigation of 190 patients conducted at five European centers, a major vascular complication (need for transfusion) with the Mynx device occurred in only 1 patient (0.5%).¹ There were no reports of new lower-extremity ischemia in either of these studies. 

Incongruous results from multiple small trials evaluating the complication rates associated with VCDs prompted the United States Food and Drug Administration to initiate a study of 166,680 patients using the American College of Cardiology National Cardiovascular Database Registry database. This study revealed a non-significant reduction in complications with VCDs compared to manual compression for patients undergoing PCI.⁵ However, there is evidence to support the use of these devices for achieving faster hemostasis and earlier ambulation and a recent meta-analysis of broadly inclusive observational and multicenter registries showed a significant decrease in vascular complications associated with VCD utilization.^6,7 Nevertheless, there has not been an appropriately powered randomized trial proving that VCDs are associated with decreased vascular complications and the most recent PCI guidelines do not recommend the routine use of VCDs for the purpose of decreasing vascular complications.⁸

The optimal method to extract material that embolizes after unsuccessful deployment of a Mynx VCD is unknown. Islam et al found that localized infusion of a thrombolytic agent was not effective at dissolving Mynx sealant and thus we felt that removal of the material was necessary.² A major concern was that manipulation of the sealant might cause it to break apart, resulting in multiple small pieces embolizing into and obstructing the vessels of the lower leg and foot. We chose not to use thrombectomy catheters or AngioJet, since our goal was to try and extract the sealant plug intact. We were unable to extract sealant material through either a 5 Fr Vertebral catheter or a 6 Fr Multipurpose guide catheter, but were successful with a 6 Fr sheath, suggesting that the Mynx sealant is not deformable and that a large lumen is necessary to remove the material intact. A distal filter would potentially have been helpful, but was not used because of concern that passing the filter through the sealant might result in embolization.

The Mynx device utilizes a water-soluble, porous, biodegradable PEG-based polymer that reportedly “dissolves within 30 days” according to the Mynx Vascular Closure Device Instructions for Use. We extracted large amounts of sealant from our patient 35 days after use of the Mynx device. This suggests that in at least some situations, PEG is not resorbed as rapidly as the device literature would imply. In this case, exposure of the sealant to the blood stream may have delayed dissolution, but this would be unexpected since PEG used in the Mynx device is “water soluble.”

Conclusion. Care should be taken when deploying the Mynx device and, in particular, minimal forward pressure should be applied when advancing the advancer tube over the sealant. In the rare case of distal embolization, aspiration with a catheter with a large internal diameter may be feasible, thereby avoiding potential vascular surgery.

References

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7. Biancari F, D'Andrea V, Di Marco C, Savino G, Tiozzo V, Catania A. Meta-analysis of randomized trials on the efficacy of vascular closure devices after diagnostic angiography and angioplasty. Am Heart J. 2010;159(4):518-531.
8. Levine GN, Bates ER, Blankenship JC, et al. 2011 ACCF/AHA/SCAI guideline for percutaneous coronary intervention. A report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines and the Society for Cardiovascular Angiography and Interventions. J Am Coll Cardiol. 2011;58(24):e44-e122.

From the Division of Cardiology, University of North Carolina Hospitals, Chapel Hill, North Carolina.

 Disclosure: The authors have completed and returned the ICMJE Form for Dis- closure of Potential Conflicts of Interest. The authors report no conflicts of interest regarding the content herein.

Manuscript submitted December 5, 2012 and accepted January 11, 2013.

Address for correspondence: George A. Stouffer, MD, Division of Cardiology, University of North Carolina, Chapel Hill, NC 27599-7075. Email: rstouff@med.unc.edu