Marcelo Guimaraes

Medical University of South Carolina, Charleston, SC, United States

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Publications (24)27.57 Total impact

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    ABSTRACT: Purpose : To report the initial clinical experience with a new hybrid stent to prevent neurological events during carotid artery stenting. Case Report : A 77-year-old asymptomatic man presented with de novo high-grade stenosis (80%) of the right internal carotid artery (ICA) and occlusion of the contralateral ICA. He was referred for right ICA stenting with a 6/8-mm×40-mm Gore Carotid Stent under cerebral protection using the Gore Carotid Filter. The stent delivery system tracked well over the filter wire and deployment was precise. The result was satisfactory, with 10% residual stenosis. No neurological events occurred during 6 months of follow-up. Conclusion : Initial clinical experience with this new carotid hybrid stent showed satisfactory results, including ease of use, precise deployment, conformability to the wall, and protection against embolization.
    Journal of endovascular therapy : an official journal of the International Society of Endovascular Specialists. 08/2014; 21(4):601-604.
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    ABSTRACT: During the last 20 years, asymptomatic patients with high-grade carotid stenosis have been treated with carotid endarterectomy and more recently with carotid artery stenting in order to prevent stroke. New, best medical treatment including statins, beta-blockers, antiplatelet therapies, and better diabetes and blood pressure control might reduce the incidence of stroke in this patient population making invasive treatment unnecessary. However, patients with asymptomatic carotid stenosis cannot be considered a homogenous population, and therefore, the therapeutic approach should take into consideration a subgroup of patients with greater risk of cerebrovascular event. Unfortunately, these risk factors are not well categorized thus far, although multiple publications have addressed each one of these factors individually. Recognizing these risk factors is essential for optimizing surveillance and therapeutic approach based on individual risk. The purpose of this article is to review such factors, including patient history, presence of embolic signals on Transcranial Doppler ultrasound, and plaque morphology. These factors should identify high risk asymptomatic individuals who could benefit from carotid stenting or carotid endarterectomy.
    The Journal of cardiovascular surgery 02/2013; 54(1):55-9. · 1.51 Impact Factor
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    ABSTRACT: In an era of increasing emphasis on minimally invasive surgery, distal embolization remains a concern in the absence of distal flow control. We present a case using an endovascular flow control technique that can be used for reducing distal embolic events during endovascular recanalization of aortoiliac occlusive disease. This technique has been used in four patients so far (two with native anatomy and two with aorto-bi-iliac grafts) with no evidence of angiographic or clinical embolic complications.
    Journal of vascular surgery: official publication, the Society for Vascular Surgery [and] International Society for Cardiovascular Surgery, North American Chapter 09/2012; 56(5):1457-60. · 3.52 Impact Factor
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    ABSTRACT: To report the technique and acute technical results associated with the PowerWire Radiofrequency (RF) Guidewire used to recanalize central vein occlusions (CVOs) after the failure of conventional endovascular techniques. A retrospective study was conducted from January 2008 to December 2011, which identified all patients with CVOs who underwent treatment with a novel RF guide wire. Forty-two symptomatic patients (with swollen arm or superior vena cava [SVC] syndrome) underwent RF wire recanalization of 43 CVOs, which were then implanted with stents. The distribution of CVOs in central veins was as follows: six subclavian, 29 brachiocephalic, and eight SVC. All patients had a history of central venous catheter placement. Patients were monitored with regular clinical evaluations and central venography after treatment. All 42 patients had successful recanalization of CVOs facilitated by the RF wire technique. There was one complication, which was not directly related to the RF wire: one case of cardiac tamponade attributed to balloon angioplasty after stent placement. Forty of 42 patients (95.2%) had patent stents and were asymptomatic at 6 and 9 months after treatment. The present results suggest that the RF wire technique is a safe and efficient alternative in the recanalization of symptomatic and chronic CVOs when conventional endovascular techniques have failed.
    Journal of vascular and interventional radiology: JVIR 06/2012; 23(8):1016-21. · 1.81 Impact Factor
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    ABSTRACT: To compare an injectable hydrogel embolic device with a pushable AZUR device procedurally, angiographically, and histologically in the embolization of porcine arteries. In 12 pigs, embolization of renal, gluteal, and hepatic or thoracic arteries was performed with either injectable hydrogel embolic devices (two arteries per pig) or an AZUR device (one artery per pig). Follow-up angiography was performed before sacrifice in five pigs at 7 days after embolization and seven pigs at 90 days after embolization. The harvested tissues were evaluated histologically. Continuous and ordinal results were compared using analysis of variance and χ(2) tests. For the sites with embolization performed with injectable hydrogel, complete angiographic occlusion was obtained in 21 of 24 (88%) sites after treatment, 10 of 10 (100%) sites at 7 days, and 10 of 14 (72%) sites at 90 days. For the sites with embolization performed with AZUR devices, complete angiographic occlusion was obtained in 10 of 12 (83%) sites after treatment, 4 of 5 (80%) sites at 7 days, and 5 of 7 (72%) sites at 90 days. Statistically significant differences in angiographic occlusion were not observed at 7 days (P = .13) or 90 days (P = .35). The embolization time of the injectable hydrogel group (14 minutes ± 8) was significantly reduced (P = .02) compared with the AZUR group (22 minutes ± 12). Differences between the groups in arterial wall damage were not evident at either 7 days or 90 days, although greater damage was observed in both groups at 90 days. In both groups, inflammation was nonexistent to minimal at 7 days and minimal to mild at 90 days. Embolization of porcine arteries was as effective with injectable hydrogel embolic devices as pushable AZUR devices, as evidenced by the procedural, angiographic, and histologic results.
    Journal of vascular and interventional radiology: JVIR 09/2011; 22(11):1619-1624.e1. · 1.81 Impact Factor
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    Marcelo Guimaraes, Mathew Wooster
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    ABSTRACT: Onyx is a nonadhesive liquid embolic agent approved for the treatment of brain arteriovenous malformations. Here, the use of Onyx is discussed in different peripheral procedures. The Onyx's features, its manipulation, technical details, tips, and tricks are presented followed by illustrative cases.
    Seminars in Interventional Radiology 09/2011; 28(3):350-6.
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    ABSTRACT: To define predictive factors for endoleak type II (EL-II) based on quantifiable factors in the imaging studies of patients undergoing endovascular aneurysm repair (EVAR). The data on 208 consecutive patients (137 men; mean age 75.2 years, range 62-84) who underwent EVAR between the years 2003 and 2008 were retrospectively reviewed. The abdominal aortic aneurysm (AAA) diameter ranged from 4.8 to 12.8 cm. Data were collected on the type of AAA; the type of stent-graft (aortomonoiliac versus bifurcated); the performance of hypogastric artery embolization; the presence, number, diameter, and patency of aortoiliac branches identified on the pre and post-EVAR imaging studies; and the presence and type of EL-II (transient vs. persistent) with the goal of identifying any imaging-based predictive factors for the development of EL-II. Among the 208 cases, 11 patients had endoleaks other than type II and were excluded, leaving 195 patients for analysis. In all, 28 (13.4%) patients were diagnosed with EL-II. All had ≥4 patent lumbar arteries (mean diameter >2.3 mm). Ten patients with a transient EL-II had a mean of 4.3 patent lumbar arteries, which had diameters <2 mm (mean 1.5 mm). In the 18 patients with persistent EL-II, the mean diameter of the 4 lumbar arteries was 2.7 mm; at least 1 of the lumbar arteries was >2 mm. The presence of at least 4 patent lumbar arteries (p<0.001) and at least 1 patent hypogastric artery (p<0.001) were predictive factors for EL-II. At least 1 lumbar artery >2 mm in diameter was a positive predictive factor for the development of persistent EL-II (p<0.001). Patent hypogastric and lumbar arteries are significantly associated with a higher risk of developing EL-II. Larger diameter lumbar arteries tend to be associated with persistent EL-IIs, while lumbar arteries <2 mm would more likely be seen with a transient EL-II. If substantiated in larger studies, these angiographic criteria may guide early treatment of EL-II to avoid aneurysm sac expansion and potential rupture.
    Journal of Endovascular Therapy 06/2011; 18(3):299-305. · 2.70 Impact Factor
  • Marcelo Guimaraes, Renan Uflacker
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    ABSTRACT: Locoregional therapies for hepatocellular carcinoma have progressed greatly in the last 30 years, beginning with the introduction of chemoembolization. Embolization techniques have evolved with the use of drug-eluting beads and radioembolization with yttrium-90. In the last 10 years, several new ablation techniques were developed including radiofrequency ablation, microwave ablation, cryoablation, laser ablation, and irreversible electroporation. Isolated or in combination, these techniques have already shown that they can improve patient survival and/or provide acceptable palliation.
    Clinics in liver disease 05/2011; 15(2):395-421, vii-x.
  • CardioVascular and Interventional Radiology 03/2011; 35(2):430-3. · 2.09 Impact Factor
  • Journal of Vascular and Interventional Radiology - J VASC INTERVEN RADIOL. 01/2011; 22(3).
  • Journal of Vascular and Interventional Radiology - J VASC INTERVEN RADIOL. 01/2011; 22(3).
  • Journal of Vascular and Interventional Radiology - J VASC INTERVEN RADIOL. 01/2011; 22(3).
  • Journal of Endovascular Therapy 10/2010; 17(5):657-9. · 2.70 Impact Factor
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    ABSTRACT: A radiofrequency (RF) wire puncture technique was used in the recanalization of biliary anastomotic occlusions in five patients. The technical success of recanalization, which was defined as successful puncture and crossing of the obstruction followed by balloon cholangioplasty and internal-external biliary drainage without evidence of complications, was 100%. The average follow-up was 13 months (range, 11-16 months). For biliary occlusion recanalization, the RF wire may allow the use of percutaneous therapy in the treatment of a subset of individuals who would otherwise have to undergo open surgical intervention.
    Journal of vascular and interventional radiology: JVIR 02/2010; 21(2):289-94. · 1.81 Impact Factor
  • Journal of Vascular and Interventional Radiology - J VASC INTERVEN RADIOL. 01/2010; 21(2).
  • Journal of Vascular and Interventional Radiology - J VASC INTERVEN RADIOL. 01/2010; 21(2).
  • Journal of Vascular and Interventional Radiology - J VASC INTERVEN RADIOL. 01/2009; 20(2).
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    ABSTRACT: Massive bleeding from a tracheostomy developed in a 65-year-old woman with stroke after successful conservative management of a minor tracheostomy bleeding episode. Temporary hemostasis was achieved, and angiography showed a tracheoinnominate fistula (TIF), a rare complication of tracheostomy. Open surgery was contraindicated in this patient, so endovascular repair using a stent graft was performed. Permanent hemostasis was obtained, and there were no immediate complications from the procedure. The patient never recovered from her stroke and died 2 weeks later. The endovascular approach may be a feasible alternative to surgical repair of TIF, especially in patients unable to tolerate an open procedure.
    Vascular 10/2008; 16(5):287-90. · 0.86 Impact Factor
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    ABSTRACT: Although rare, misplacement of central venous catheters in supra-aortic arteries is potentially fatal. Five patients had safe catheters removal using percutaneous closure devices. Three patients were coagulopathic, 3 under intensive care and 1 in immediate postoperative limb amputation. Patients were treated successfully, with immediate hemostasis and without complications in a mean follow-up of 12.5 months. Although the number of patients is small, the closure devices proved to be safe. This is a minimally invasive alternative technique in the management of large bore catheters removed from non-compressible puncture sites such as subclavian and brachiocephalic arteries.
    The Journal of cardiovascular surgery 07/2008; 49(3):345-50. · 1.51 Impact Factor
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    ABSTRACT: OBJECTIVE: Our purpose was to evaluate the role of sonography in the early follow-up of patients with a covered transjugular intrahepatic portosystemic shunt (TIPS). CONCLUSION: Routine baseline Doppler sonography should occur 7-14 days after shunt placement unless malfunction or procedural complications are suspected.
    American Journal of Roentgenology 05/2006; 186(4):1138-43. · 2.90 Impact Factor