MVP™ Micro Vascular Plug Systems for the Treatment of Pulmonary Arteriovenous Malformations

Use of Polyurethane-Covered Stents for Exclusion of Pulmonary Arteriovenous Malformations

PURPOSE

To evaluate the safety, technical success and short-term effectiveness of polyurethane-covered stent (PK Papyrus, BioTronik, Berlin) in the treatment of pulmonary arteriovenous malformations (PAVMs) that are not amenable to embolotherapy.

MATERIALS AND METHODS

In this IRB-approved, retrospective study, data from patients who received polyurethane-covered stents for exclusion of PAVMs were analyzed. The study included 5 patients (all women) with a median age of 40 years (range 25-60). Patients presented with hypoxemia, TIAs, and/or epistaxis; 4 were confirmed to have HHT. All had multiple PAVMs diagnosed on chest CT and underwent embolization with other devices in addition to the polyurethane-covered stent. The indication for stent placement in all cases was a short and/or tortuous feeding artery. Safety was assessed by immediate or short-term complications, e.g., migration, stent thrombosis, and fracture. Technical success was defined as the ability to accurately place the stent at the intended location. Effectiveness was defined as successful exclusion of PAVM with no perfusion across the AVM.

RESULTS

Technical success of stent placement was 100%. AVM exclusion rate was 80% after single stent deployment; in the case of incomplete exclusion, success was achieved using an overlapping stent to completely cover a second feeding artery. During the median follow-up period of 5 months (range 2-10), all stents remained patent, and AVMs were excluded without other complications.

CONCLUSION

Exclusion of PAVMs with polyurethane-covered stents is technically feasible, safe, and shows short-term effectiveness for PAVMs with a short/tortuous feeding artery when traditional embolization techniques are not possible.

Prospective Study of Polytetrafluoroethylene-Covered Microplugs and Detachable Coils for Embolization of Pulmonary Arteriovenous Malformations: Technical Results, Procedure Times, and Costs

PURPOSE

To determine time to occlusion and procedure costs of embolization of pulmonary arteriovenous malformations (PAVMs) using a polytetrafluoroethylene-covered microplug compared with embolization using detachable coils.

MATERIALS AND METHODS

In this prospective study, 37 patients (mean age, 39.1 years [SD ± 17.6]) with 82 PAVMs underwent embolization with microplug or detachable coils between April 2019 and January 2023. Technical success, procedure time intervals, and costs were analyzed.

RESULTS

In 37 patients, 82 PAVMs and 101 feeding arteries were successfully treated (microplug, 64; microplug + another device, 5; detachable coils alone, 32). Time from embolic device inserted into the catheter to device deployed and time to occlusion differed significantly between microplug and detachable coil cohorts (P < .0001 for both). Embolization with ≥1 microplug had a significantly shorter occlusion time than embolization with detachable coils (median, 10.0 minutes saved per feeding artery) (P < .0001). Compared with detachable coil embolization, microplug embolization saved a median of 9.0 minutes per feeding artery (P < .0001) and reduced room cost by a median of $429 per feeding artery (P < .0001). Device costs per feeding artery did not differ significantly between microplug ($2,790) and detachable coil embolization ($3,147) (P = .87).

CONCLUSIONS

Compared with coils, microplugs had an equally high technical success rate but significant time to occlusion and room costs savings per feeding artery. Total room cost and device cost together did not differ significantly between microplugs and coils. Microplugs may be considered technically effective and at least cost-neutral for PAVM embolization where clinically appropriate.

Embolization of De Novo Pulmonary Arteriovenous Malformations Using High-Volume Detachable Non-Fibered Coils: Propensity-Matched Comparison to Traditional Coils

Embolization of de novo pulmonary arteriovenous malformations (PAVMs) using high-volume detachable non-fibered (HVDNF) coils was compared to traditional non-HVDNF coils. Persistent-occlusion rates were evaluated. A total of 272 de novo (previously untreated) PAVM treatments were retrospectively stratified into those treated with non-HVDNF coils only (n = 192) and those treated with HVDNF coils with or without other coils (n = 80). Propensity score matching, followed by survival analysis and cost analysis, was performed. The overall persistent-occlusion rate was 86.0% (234/272). Persistent occlusion was achieved in 81.8% of PAVMs using non-HVDNF coils, compared with 96.3% using HVDNF coils (p = 0.0017). The mean follow-up was 30.7 ± 31.9 months versus 14.7 ± 13.4 months, respectively (p < 0.0001). Propensity-matched survival analysis demonstrated PAVMs treated with HVDNF coils recurred significantly less frequently than PAVMs treated with non-HVNDF coils (p = 0.023). The use of HVDNF coils was more expensive than standard coils, however not significantly different for the treatment of complex PAVMs. The use of high-volume detachable non-fibered coils was associated with higher persistent-occlusion rates when compared with non-HVDNF coils. HVDNF coils were more expensive on average; however, cost was similar between groups for the treatment of complex PAVMs.

Outcomes of manually modified microvascular plugs to pulmonary flow restrictors in various congenital heart lesions

Background

The development of microvascular plugs (MVPs) has enabled novel transcatheter deliverable endoluminal pulmonary flow restrictors (PFRs) with the potential to treat newborns and infants with life-threatening congenital heart diseases (CHDs) in a minimally invasive manner. We present our experience to evaluate the efficacy of this concept in controlling pulmonary blood flow in various CHDs.

Methods

Retrospective clinical data review of patients with CHD and pulmonary over-circulation who received bilateral PFRs percutaneously.

Results

Twenty-eight PFRs (7 MVP-5Q, 12 MVP-7Q, and 9 MVP-9Q) were finally implanted in 14 patients with a median age of 1.6 months (IQR, 0.9-2.3) and a median weight of 3.1 Kg (IQR, 2.7-3.6). Nine patients had large intra-cardiac left-to-right shunts (including 3 with fatal trisomy and palliative programs), 2 had borderline left ventricles, 2 had Taussig-Bing anomaly, and one had a hypoplastic left heart. Four patients had concomitant ductal stenting. Two MVP-5Qs were snare-removed and upsized to MVP-7Q. Patients experienced a significant drop in oxygen saturation and Qp/Qs. All patients were discharged from the ICU after a median of 3.5 days (IQR, 2-5.8) postoperative. Five patients had routine inter-stage catheterization and no device embolization or pulmonary branch distortion was seen. Fourteen (50%) PFRs were surgically explanted uneventfully on a median of 4.3 months (IQR, 1.2-6) post-implantation during biventricular repair in 6 patients and stage-2 palliation in one patient. The latter died 1 month post-operative from severe sepsis. Four patients are scheduled for surgical PFR removal and biventricular repair. Two patients with trisomy 18 died at 1 and 6.8 months post-procedure from non-cardiac causes. One patient with trisomy 13 is alive at 2.7 months post-procedure.

Conclusion

It is feasible to bespoke MVPs and implant them as effective PFRs in various CHDs. This approach enables staged left ventricular recruitment, comprehensive stage-2 or biventricular repair with lower risk by postponing surgeries to later infancy. Device explantation is uneventful, and the outcomes afterward are promising.

Retrospective single-arm cohort study of video-assisted thoracic surgery for treatment of idiopathic peripherally located simple type pulmonary arteriovenous malformation in 23 consecutive patients

BACKGROUND

Although case reports of video-assisted thoracic surgery (VATS) for pulmonary arteriovenous malformation (PAVM) have been published, studies analyzing more than 10 cases were limited. A retrospective single-arm cohort study was performed to investigate the efficacy of VATS in 23 consecutive patients with idiopathic peripherally located simple type PAVM.

METHODS

VATS was performed for wedge resection of 24 PAVMs in 23 patients, which included 4 males and 19 females with an age range of 25 to 80 years (mean: 59.6 ± 13.0). Two patients underwent simultaneous resection of lung carcinoma, one by wedge resection and another by lobectomy. Each medical record was analyzed according to the resected specimen, bleeding volume, postsurgical hospital stay length, duration of chest tube placement, and VATS time. The distance between pleural surface/fissure and PAVM was measured on CT, and the influence of this distance on identification of PAVM was investigated.

RESULTS

In all 23 patients, VATS was successfully performed, and the venous sac was included in each resected specimen. Bleeding volume was less than 10mL in all but one with 1900 mL bleeding volume due to simultaneous lobectomy for carcinoma, not wedge resection of PAVM. Postsurgical hospital stay length, duration of chest tube placement, and VATS time were 5.0 ± 1.4 days, 2.7 ± 0.7 days, and 49.3 ± 39.9 min, respectively. In 21 PAVMs with a distance of 1 mm or less, purple vessel or pleural bulge of PAVM was identified soon after insertion of a thoracoscope. In the remaining 3 PAVMs with a distance of 2.5 mm or more, additional efforts were needed for identification.

CONCLUSION

VATS was found to be a safe and effective to treatment for idiopathic peripherally located simple type PAVM. When the distance between pleural surface/fissure and PAVM was 2.5 mm or more, a plan and strategy for identification of PAVM should be prepared before VATS.

Postembolization Persistence of Pulmonary Arteriovenous Malformations: A Retrospective Comparison of Coils and Amplatzer and Micro Vascular Plugs Using Propensity Score Weighting

BACKGROUND. Endovascular embolization of pulmonary arteriovenous malformations (PAVMs) was historically performed with embolic coils. The Amplatzer Vascular Plug device (AVP) was introduced for this purpose in 2007 and the Micro Vascular Plug device (MVP) in 2013. OBJECTIVE. The purpose of this study was to compare coils, AVPs, and MVPs in terms of risk of persistence after PAVM embolization by use of propensity score weighting to account for biases in device selection. METHODS. This retrospective study included 112 patients (78 women and girls, 34 men and boys; mean age, 45 years) who underwent embolization of 393 PAVMs with a single device type (coil, MVP, or AVP) from January 2003 to January 2020. Persistence was defined as less than 70% reduction in PAVM sac size or contrast enhancement of the sac on follow-up pulmonary CTA. A Cox proportional hazards regression model was used to assess associations between embolic device selection and PAVM persistence. Inverse propensity score weighting was used to account for differences in embolic device selection based on patient and PAVM characteristics. RESULTS. The median postembolization follow-up period was 1.5 years (IQR, 0.3-5.6 years). Persistence was found in 10% (41/393) of PAVMs, including 16% (34/207) of those treated with coils, 8% (7/88) of those treated with AVPs, and 0% (0/98) of those treated with MVPs. Variables associated with embolization device (p < .25) were age, sex, pediatric versus adult status, smoking status, PAVM complexity, PAVM laterality, number of feeding arteries, and feeding artery diameter. The Cox regression model incorporated inverse propensity score weighting to account for the differences between treatment groups in these variables and incorporated feeding artery diameter because of imbalance remaining after weighting. With coils as the referent, MVPs had a hazard ratio for persistence of less than 0.01 (95% CI, < 0.01 to < 0.01; p < .001), and AVPs had a hazard ratio of 0.37 (95% CI, 0.16-0.90; p = .03). CONCLUSION. The risk of persistence after PAVM embolization was significantly lower for MVPs alone than for coils or AVPs alone. In addition, the risk of persistence was lower for AVPs than for coils. CLINICAL IMPACT. The findings support the clinical use of MVPs as the preferred device for PAVM embolization over coils and polytetrafluoroethylene-covered plugs.

Embolization of vascular abnormalities in children with congenital heart diseases using medtronic micro vascular plugs

This study aimed at evaluating our experience with Micro Vascular Plug (MVP) for embolization of vascular abnormalities in children with congenital heart diseases (CHDs). MVP is one of the most recent additions to the armamentarium for peripheral embolization. Data on its use in congenital cardiology are scarce. Medical records of children with CHDs who had embolizations with MVPs between April 2015 and September 2020 were reviewed. Immediate and follow-up data were assessed. A total of 153 patients underwent 172 procedures during which 240 embolizations using 259 MVPs were attempted. Median age and weight were 34.9 months (IQR, 4-75 months) and 12.5 kg (IQR, 4.8-19.4 kg), respectively. Targets were abnormal systemic arteries (n = 163), patent arterial ducts (n = 26), venous (n = 45), and coronary-cameral fistulas (n = 6). Median vessel diameter was 3.3 mm (IQR, 2.5-4 mm). Veins were larger than arteries (2.3 mm > 2.1 mm, p < 0.01). MVPs were implanted in narrower diameters compared to manufacturer's recommendations. Compared to veins, solitary implanted MVPs in arteries were additionally oversized at 12.4%, 5.1%, and 7.9% for MVP-3Q, 5Q, and 7Q, respectively. Additional occlusion material (16.7%) and 2 MVPs (5.8%) were needed at the same site for complete closure. Implantation and procedure success rates were 99.2% and 96.7%, respectively. Five complications were treated percutaneously (n = 4) and surgically (n = 1). Efficacy of vascular embolization using MVPs was demonstrated in the largest cohort of children with CHDs and a variety of clinical settings. Immediate and stable closure is obtained with a single device in most cases. Detailed device selection chart according to vessel type and diameter is proposed to achieve intended outcomes.

Imaging Manifestations and Interventional Treatments for Hereditary Hemorrhagic Telangiectasia

Hemorrhagic hereditary telangiectasia (HHT) is a rare autosomal dominant disorder that causes multisystem vascular malformations including mucocutaneous telangiectasias and arteriovenous malformations (AVMs). Clinical and genetic screening of patients with signs, symptoms, or a family history suggestive of HHT is recommended to confirm the diagnosis on the basis of the Curaçao criteria and prevent associated complications. Patients with HHT frequently have epistaxis and gastrointestinal bleeding from telangiectasias. Pulmonary AVMs are common right-to-left shunts between pulmonary arteries and veins that can result in dyspnea and exercise intolerance, heart failure, migraine headaches, stroke or transient ischemic attacks, brain abscesses, or in rare cases, pulmonary hemorrhage. Primary neurologic complications from cerebral AVMs, which can take on many forms, are less common but particularly severe complications of HHT. Multimodality imaging, including transthoracic echocardiography, Doppler US, CT, and MRI, is used in the screening and initial characterization of vascular lesions in patients with HHT. Diagnostic angiography is an important tool in characterization of and interventional treatments for HHT, particularly those in the lungs and central nervous system. A multidisciplinary approach to early diagnosis, treatment, imaging, and surveillance at high-volume HHT Centers of Excellence is recommended. Although a variety of idiopathic, traumatic, or genetic conditions can result in similar clinical and imaging features, the Curaçao criteria are particularly useful for the proper diagnosis of HHT. Imaging and treatment options are reviewed, with a focus on screening, diagnosis, and posttreatment findings, with the use of updated international guidelines. Online supplemental material is available for this article. ^©RSNA, 2021.

Embolization with MVP (Micro Vascular Plug®): experience on 104 patients in emergent and elective scenarios

AIM

To describe a 3 years experience of peripheral arterial embolization with Micro Vascular Plug (MVP) (Medtronic, USA).

MATERIALS AND METHODS

The following parameters were investigated: type of vascular injury, anticoagulation therapy at time of procedure, anatomical district, caliper of the target artery, course of the landing zone, additional embolics, technical and clinical success, device related clinical complications. Technical success was defined as complete embolization without deployment of additional embolics after MVP release. Primary clinical success was considered as hemodynamic stability in emergency setting and resolution of the underlying vascular pathology in elective cases; secondary clinical success was considered clinical success after a second embolization session.

RESULTS

116 MVP have been released in 104 patients (67 males and 37 females; mean age 61.3 years). The pullback release technique was adopted in each case. 85 patients were treated in emergent settings while in 19 patients the procedure was scheduled. The overall technical success was 75%. Primary clinical success was 96.1%, secondary clinical success 3% and clinical failure 0.9%. No statistical differences in terms of effectiveness were observed among patients assuming anticoagulation (p-value = 0.6). A straight and longer landing zone were statistically associated with higher technical success compared to curved and shorter ones, (p-values < 0.001 and = 0.048 respectively). MVP-3 and MVP-5 were the most frequently adopted models in this sample, in 29.8% and 49% of the patients respectively. No clinically adverse events directly related to MVP occurred; in 3 cases device migration was registered without clinical complications.

CONCLUSION

MVP is a safe and effective embolic agent. While eventual concomitant anticoagulation therapy did not influence the technical outcome, straight course and length of the landing zone are essential parameters to evaluate before deployment.

Visceral Artery Aneurysms Embolization and Other Interventional Options: State of the Art and New Perspectives

Visceral artery aneurysms (VAAs) are rare, usually asymptomatic and incidentally discovered during a routine radiological examination. Shared guidelines suggest their treatment in the following conditions: VAAs with diameter larger than 2 cm, or 3 times exceeding the target artery; VAAs with a progressive growth of at least 0.5 cm per year; symptomatic or ruptured VAAs. Endovascular treatment, less burdened by morbidity and mortality than surgery, is generally the preferred option. Selection of the best strategy depends on the visceral artery involved, aneurysm characteristics, the clinical scenario and the operator's experience. Tortuosity of VAAs almost always makes embolization the only technically feasible option. The present narrative review reports state of the art and new perspectives on the main endovascular and other interventional options in the treatment of VAAs. Embolization techniques and materials, use of covered and flow-diverting stents and percutaneous approaches are accurately analyzed based on the current literature. Visceral artery-related considerations and targeted approaches are also provided and discussed.

Location of embolization affects patency after coil embolization for pulmonary arteriovenous malformations: importance of time-resolved magnetic resonance angiography for diagnosis of patency

OBJECTIVES

This study aimed to assess the diagnostic accuracy of computed tomography (CT) and time-resolved magnetic resonance angiography (TR-MRA) for patency after coil embolization of pulmonary arteriovenous malformations (PAVMs) and identify factors affecting patency.

METHODS

Data from the records of 205 patients with 378 untreated PAVMs were retrospectively analyzed. Differences in proportional reduction of the sac or draining vein on CT between occluded and patent PAVMs were examined, and receiver operating characteristic analysis was performed to assess the accuracy of CT using digital subtraction angiography (DSA) as the definitive diagnostic modality. The accuracy of TR-MRA was also assessed in comparison to DSA. Potential factors affecting patency, including sex, age, number of PAVMs, location of PAVMs, type of PAVM, and location of embolization, were evaluated.

RESULTS

The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of CT were 82%, 81%, 77%, 85%, and 82%, respectively, when the reduction rate threshold was set to 55%, which led to the highest diagnostic accuracy. The sensitivity, specificity, PPV, NPV, and accuracy of TR-MRA were 89%, 95%, 89%, 95%, and 93%, respectively. On both univariable and multivariable analyses, embolization of the distal position to the last normal branch of the pulmonary artery was a factor that significantly affected the prevention of patency.

CONCLUSIONS

TR-MRA appears to be an appropriate method for follow-up examinations due to its high accuracy for the diagnosis of patency after coil embolization of PAVMs. The location of embolization is a factor affecting patency.

KEY POINTS

• Diagnosis of patency after coil embolization for pulmonary arteriovenous malformations (PAVMs) is important because a patent PAVM can lead to neurologic complications. • The diagnostic accuracies of CT with a cutoff value of 55% and TR-MRA were 82% and 93%, respectively. • The positioning of the coils relative to the sac and the last normal branch of the artery was significant for preventing PAVM patency.

Massive Orofacial Hemorrhage Treated with the Micro Vascular Plug System

BACKGROUND

This case series describes the use of the Medtronic Micro Vascular Plug (MVP) system in the treatment of acute massive orofacial hemorrhages in patients with cancer and trauma, resulting in successful hemostasis in these emergent cases.

CASE DESCRIPTION

The first case describes a patient who presented with life-threatening oropharyngeal hemorrhage after a motor vehicle accident. In the second case, a patient with oropharyngeal cancer presented with life-threatening bleeding from an ulcerated tumor. Patients were successfully treated with a combination of MVP and coils. Immediate postprocedural imaging confirmed that homeostasis was achieved.

CONCLUSIONS

These cases demonstrate that the MVP as an embolic device is a valuable transarterial embolic treatment option in cases of acute orofacial bleeding where rapid, effective hemostasis is required.

Approach to Pulmonary Arteriovenous Malformations: A Comprehensive Update

Pulmonary arteriovenous malformations (PAVMs) are abnormal direct vascular communications between pulmonary arteries and veins which create high-flow right-to-left shunts. They are most frequently congenital, usually in the setting of hereditary hemorrhagic telangiectasia (HHT). PAVMs may be asymptomatic or present with a wide variety of clinical manifestations such as dyspnea, hypoxemia, or chest pain. Even when asymptomatic, presence of PAVMs increases patients' risk of serious, potentially preventable complications including stroke or brain abscess. Transcatheter embolotherapy is considered the gold standard for treatment of PAVMs. Though previous guidelines have been published regarding the management of PAVMs, several aspects of PAVM screening and management remain debated among the experts, suggesting the need for thorough reexamination of the current literature. The authors of this review present an updated approach to the diagnostic workup and management of PAVMs, with an emphasis on areas of controversy, based on the latest literature and our institutional experience.

MVP (Micro Vascular Plug®) embolization of severe renal hemorrhages after nephrostomic tube placement

Background

We report our experience in managing iatrogenic renal bleedings after nephrostomic procedures by transarterial embolization using Micro Vascular Plug (MVP) (Medtronic, USA) as single or complementary embolization device with parenchimal sparing.

Materials and methods

Five patients have been treated in a single center with transarterial embolization because of renal hemorrhages occurring after positioning of nephrostomic drainages.

All patients presented with back pain, severe hematuria and/or bright red blood into the nephrostomic bag, with fall in hemoglobin value.

After contrast enhanced CT scan confirming arterial active bleeding, rescue embolization was performed using MVP.

The renal parenchimal loss was estimated on final postembolization DSA. Creatinine values were monitored before and after the procedure.

Results

Technical and clinical successes were obtained in all patients.

Two patients presented with extraluminal blush, one with multiple pseudoaneurysms, one with pseudoaneurysm with arterovenous fistula, one with extraluminal blush with arterovenous fistula.

MVP models were choosen oversized because of vasospasm that would underestimate the effective caliber of target vessel; MVP 3Q and MVP 7Q were adopted in one patient each, while MVP 5Q was released in three cases.

MVP was the sole embolizing agent in four patients; in one patient, MVP was employed after microcoils failed to obtain complete embolization.

The percentage of renal parenchimal lost was lower than 20%; no increase in Creatinine values was detected at dismission.

Conclusions

According to proposed data, MVP seems to be a safe, effective and fast embolizing device that interventionalists could consider when facing renal bleedings, even as sole agent.

Retrospective Comparison of Pulmonary Arteriovenous Malformation Embolization with the Polytetrafluoroethylene-Covered Nitinol Microvascular Plug, AMPLATZER Plug, and Coils in Patients with Hereditary Hemorrhagic Telangiectasia

PURPOSE

To evaluate effectiveness of the polytetrafluoroethylene-covered nitinol mesh microvascular plug (MVP) and compare it with other devices in pulmonary arteriovenous malformation (PAVM) embolization in patients with hereditary hemorrhagic telangiectasia (HHT).

MATERIALS AND METHODS

Twenty-five patients (average age 35 y; range, 15-56 y) with hereditary hemorrhagic telangiectasia (HHT) and de novo PAVM embolization with at least 1 MVP between November 2015 and May 2017 were retrospectively evaluated. Retrospective data were also obtained from prior embolization procedures in the same patient population with other embolic devices dating back to 2008. Technical success, complications, PAVM persistence rates, and category of persistence were analyzed.

RESULTS

In 25 patients, 157 PAVMs were treated: 92 with MVP, 35 with AMPLATZER vascular plug (AVP), 6 with AVP plus coils, and 24 with coils. The per-PAVM technical success rates were 100% with MVP; 97%, AVP; 100%, AVP plus coils; and 100%, coils. PAVM persistence rates and median follow-up were as follows: MVP, 2% (1/92) (510 d); AVP, 15% (3/20) (1,447 d); AVP plus coils, 20% (1/5) (1,141 d); coils, 46.7% (7/15) (1,141 d). Persistence owing to recanalization for MVP, AVP, AVP plus coils, and coils was 2%, 15%, 0%, and 33%. No difference was found between persistence rates of MVP vs AVP (P = .098). Embolization with a vascular plug (MVP or AVP) with or without coils had a statistically significant lower persistence rate (5.4%) than embolization with coils alone (46.7%) (P = .022).

CONCLUSIONS

PAVM embolization with MVP had a high technical success rate and a low persistence rate comparable to AVP and lower than coil embolization alone.