Membrane-covered stents: a new treatment strategy for saphenous vein graft lesions

High-flow carotid cavernous fistula and the use of a microvascular plug system: initial experience

PURPOSE

We report our initial experience using a detachable microvascular plug system to occlude the internal carotid artery during endovascular treatment of high-flow carotid cavernous fistula.

CASE AND TECHNIQUE

An 87-year-old patient was admitted for acute-onset double vision with associated right-eye ptosis. Exam revealed a pupil-sparing, partial right third cranial nerve palsy. MRI showed a carotid cavernous fistula with high-flow drainage. Digital subtraction angiography showed a high-flow, right-sided, direct carotid cavernous fistula with flow from the proximal right internal carotid artery. The ophthalmic artery, posterior communicating artery and anterior communicating arteries supplied retrograde flow to the fistula through the internal carotid artery. Obliteration of the fistula was achieved through coil embolization in combination with proximal and distal microvascular plugs (Reverse Medical, Irvine, Calif., USA).

CONCLUSION

The microvascular plug is a new addition to current endovascular embolization devices for the treatment of high-flow, direct carotid cavernous fistulas. This technique offers easy navigability through tortuous arteries, precise localization and immediate occlusion, which may allow shorter procedure and fluoroscopy times and increased cost-effectiveness. Larger case series are needed to support our observation.

Successful trapping of an organized thrombus in a coronary artery aneurysm in myocardial infarction: case report and literature review

A 44-year-old female presented with acute inferior myocardial infarction. Emergency coronary angiography showed an aneurysm of the proximal right coronary artery and an occlusion of the vessel downstream due to a huge organized thrombus. Mechanical fragmentation, glycoprotein IIb/IIIa antagonist, and intracoronary thrombolysis were all tested without success. Finally, the aneurysm was covered with a standard bare metal stent in order to trap the thrombus between the stent and the vessel wall and at least partially in the aneurysm. The strategy was successful, and after 1 week, the blood flow in the right coronary artery was normal; however, the aneurysm remained. After 6 months, there was significant in-stent restenosis of the proximal and mid segments of the right coronary artery but no evidence of the aneurysm. The restenosis was treated with two drug-eluting stents, leading to an excellent result after a further 6 months. The patient was free of symptoms and the left ventricular ejection fraction was within the normal range.

Treatment of aortocoronary graft lesions with graft-stents

OBJECTIVE

Previous controlled trials do not indicate a superiority of the polytetrafluoroethylene membrane-covered stent graft compared with a conventional stent with respect to acute results, restenosis, or clinical event rates. We evaluated the outcome of stenting aortocoronary bypass grafts with polytetrafluoroethylene-covered stent.

METHODS

The study included 64 patients who had 73 saphenous graft-stent implants. Clinical follow-up was obtained for a median of 6.2 months (1-9 months) for 54 patients.

RESULTS

The mean age of the grafts was 9.2+/-6 years (2-14 years). Procedural success was achieved in 72 of 73 lesions (98.6%). One patient having an anterior Q-wave myocardial infarction died on the second day of procedure. Four patients (6.2%) sustained distal embolization and no reflow. No reflow was overcome after intracoronary administration of nitroglycerine and verapamil in two cases. At follow-up, stable angina pectoris had developed in 10 patients (18%), unstable angina pectoris in two patients (3.7%), acute myocardial infarction in two patients (3.7%), and cardiac death in one patient (1.8%). A total of 45 patients had a coronary angiogram at 6 months of follow-up or earlier, and restenosis at the target site was detected in eight of 53 lesions (15%).

CONCLUSIONS

Saphenous graft lesions can be managed successfully with polytetrafluoroethylene-covered stents with acceptable long-term clinical outcome. Further and larger studies are needed to compare conventional stents, polytetrafluoroethylene-covered stents, drug eluting stents, and additional benefit of distal protection devices in these subgroups.

Biodegradable membrane-covered stent from chitosan-based polymers

Membrane-covered devices could help treat disease of the vasculature such as aneurysm, rupture, and fistulas. They are also investigated to reduce embolic complication associated with revascularization of saphenous vein graft. The aim of this study is to design a clinically applicable biodegradable membrane-covered stent based on the natural polysaccharide chitosan, which has been developed. The mechanical properties of the membrane is optimized through blending with polyethylene oxide (70:30% Wt CH:PEO). The membrane was able to sustain the mechanical deformation of the supporting self-expandable metallic stents during its deployment. The membrane was demonstrated to resist physiological transmural pressure (burst pressure resistance >500 mm Hg) and presented a high-water permeation resistance (1 mL/cm(2) min(-1) at 120 mmHg). The CH-PEO membrane showed a good hemocompatibility in an ex vivo assay. Heparin and hyaluronan surface complexation with the membrane further reduced platelet adhesion by 50.1 and 63% (p = 0.05). The ability of the membrane-covered devices to be used as a drug reservoir was investigated using the nitric oxide donor sodium nitroprusside (SNP). SNP-loaded membranes displayed significantly reduced platelet adhesion.

Pivotal, randomized U.S. study of the Symbiot™ covered stent system in patients with saphenous vein graft disease: Eight-month angiographic and clinical results from the Symbiot III trial

OBJECTIVES

The purpose of this study was to evaluate the clinical and angiographic outcomes of the Symbiot ePTFE covered stent versus bare metal stents (BMS) for the treatment of saphenous vein graft (SVG) disease.

BACKGROUND

The Symbiot stent was developed to reduce periprocedural complications, by potentially preventing distal embolization, and to serve as a possible barrier to cell migration, thus reducing restenosis.

METHODS

Symbiot III is a prospective, randomized trial of 400 patients at 45 US sites, with 201 patients in the Symbiot group and 199 in the BMS group. Randomization was stratified based on the intended use of embolic protection devices and glycoprotein IIb/IIIa inhibitors. The primary endpoint was percent diameter stenosis (%DS) as measured by quantitative coronary angiography at 8 months. Secondary endpoints included MACE (cardiac death, MI, TVR).

RESULTS

The groups were well matched for all baseline clinical and lesion characteristics. At 8 months, %DS was comparable between groups (30.9% Symbiot, 31.9% BMS, P = 0.80). Although the rates of binary restenosis in the stented segment were similar (29.1% Symbiot, 21.9% BMS, P = 0.17), more patients in the Symbiot group had binary restenosis at the proximal edge (9.0% Symbiot, 1.8% BMS, P = 0.0211). There was no difference in the incidence of MACE between groups (30.6% Symbiot, 26.6% BMS, P = 0.43).

CONCLUSIONS

This study failed to show an advantage for the Symbiot stent in the treatment of degenerated SVGs. This PTFE covered stent does not appear to act as a barrier to prevent restenosis.

Procedural results and distal embolization after saphenous vein graft stenting and angioplasty for in-stent restenosis of grafts

Saphenous vein graft (SVG) angioplasty is associated with frequent periprocedural complications due to distal embolization and a high risk of restenosis. The purpose of this single-center, retrospective study was to determine the distal embolization incidences and outcomes of stenting for SVG lesions and percutaneous angioplasty for in-stent restenosis of these SVGs. We studied 48 consecutive patients (mean age, 62 +/- 7 years, 92% men) who had prior CABG and underwent stent deployment to SVG lesions detected at our institution over a period of 4 years. Mean lesion length was 12.4 +/- 3.2 mm. The minimal lumen diameter increased from 0.7 +/- 0.3 mm to 3.2 +/- 0.4 mm after stenting. Distal embolization as no reflow/slow flow phenomenon occurred in 5 (10%) patients. Angiographic success was achieved in 98% of the patients. Procedural success was achieved in 96% of the patients. No reflow/slow flow phenomenon was observed, particularly in patients with acute coronary syndrome. During the follow-up, 11 patients (23%) had angiographic evidence of restenosis. Lesions were treated with balloon angioplasty and the minimal lumen diameter increased from 2.6 +/- 1.1 mm to 3.1 +/- 0.3 mm. The angiographic and procedural success rates were both 100%. There were no cases of "no" reflow/slow flow. Restenosis was particularly frequent in patients with diabetes mellitus, hypercholesterolemia, and acute coronary syndrome. Stent implantation in patients with de novo SVG lesions can be achieved with a high rate of angiographic and procedural success. The distal embolization risk is lower during angioplasty of in-stent restenosis lesions of SVGs compared to de novo SVG lesions.

Randomized evaluation of polytetrafluoroethylene-covered stent in saphenous vein grafts: the Randomized Evaluation of polytetrafluoroethylene COVERed stent in Saphenous vein grafts (RECOVERS) Trial

BACKGROUND

Treatment of lesions located in saphenous vein grafts (SVGs) is associated with increased procedural risk and a high rate of restenosis.

METHODS AND RESULTS

We conducted a randomized, multicenter trial to evaluate the usefulness of a polytetrafluoroethylene (PTFE)-covered stent compared with a bare stainless steel (SS) stent for prevention of restenosis and major adverse cardiac events (MACE) in patients undergoing SVG treatment. The primary end point was angiographic restenosis at 6 months. Secondary end points were 30-day and 6-month MACE rates, defined as the cumulative of death, myocardial infarction (MI), and target lesion revascularization. Between September 1999 and January 2002, 301 patients with SVG lesions were randomized to either the PTFE-covered JoStent coronary stent graft (PTFE group, n=156) or the SS JoFlex stent (control group, n=145). Angiographic and procedural success rates were similar between the 2 groups (97.4% versus 97.9% and 87.3% versus 93.8%, respectively). The incidence of 30-day MACE was higher in the PTFE group (10.9% versus 4.1%, P=0.047) and was mainly attributed to MI (10.3% versus 3.4%, P=0.037). The primary end point, the restenosis rate at 6-month follow-up, was similar between the 2 groups (24.2% versus 24.8%, P=0.237). Although the 6-month non-Q-wave MI rate was higher in the PTFE group (12.8% versus 4.1%, P=0.013), the cumulative MACE rate was not different (23.1% versus 15.9%, P=0.153).

CONCLUSIONS

The study did not demonstrate a difference in restenosis rate and 6-month clinical outcome between the PTFE-covered stent and the SS stent for treatment of SVG lesions. However, a higher incidence of nonfatal myocardial infarctions was found in patients treated with the PTFE-covered stent.