In-stent restenosis (ISR) after carotid angioplasty and stenting is becoming evident as more patients undergo carotid stenting and duplex scan surveillance. While redo endovascular therapy has been immediately successful, recurrent stenosis remains a problem. The ideal management of ISR has not been determined. Three cases of symptomatic ISR that were successfully treated by standard carotid endarterectomy (CEA) with removal of the stent are reported herein. Current options for management of ISR are reviewed from the literature.
This study examines the relative contributions of intraluminal pressure, blood flow, wall tension, and shear stress to the development of myointimal thickening in experimental vein grafts. To study these different hemodynamic parameters, several experimental models were created in 30 New Zealand White rabbits separated into six groups: common carotid interposition vein grafts harvested at 4 weeks (VG-4) or 12 weeks (VG-12), common carotid-linguofacial vein arteriovenous fistulas harvested at 4 weeks (AVF-4) or 12 weeks (AVF-12), AVFs with partial outflow obstruction harvested at 4 weeks (AVFobs), and combination VG-AVFs in series harvested at 4 weeks (VGAVF). Blood pressure and flow in the graft or vein were measured by use of a transducer-tipped pressure catheter and electromagnetic flow meter. At harvest, veins were perfusion-fixed and proximal, middle, and distal sections were subjected to computerized morphometric analysis. Vein grafts were characterized by a high mean pressure (VG-4, 51 +/- 4; VG-12, 62 +/- 3 mm Hg), low mean flow (VG-4, 17 +/- 1; VG-12, 16 +/- 4 ml/min), large luminal area (VG-4, 19.7 +/- 2.4; VG-12, 19.3 +/- 3.9 mm2), high wall tension (VG-4, 17.0 +/- 1.5; VG-12, 19.5 +/- 2.4 x 10(3) dyne/cm), low shear stress (VG-4, 0.75 +/- 0.13; VG-12, 0.96 +/- 0.38 dyne/cm2), and a high degree of myointimal thickening (VG-4, 5.89 +/- 0.90; VG-12, 4.72 +/- 0.83 mm2). Arteriovenous fistulas were characterized by a low mean pressure (AVF-4, 5 +/- 1, AVF-12, 6 +/- 2 mm Hg), elevated blood flow (AVF-4, 82 +/- 16; AVF-12, 82 +/- 17 ml/min), small luminal area (AVF-4, 2.43 +/- 0.58; AVF-12, 7.14 +/- 2.68), low wall tension (AVF-4, 0.62 +/- 0.19; AVF-12, 0.89 +/- 0.24 x 10(3) dyne/cm), elevated shear stress (AVF-4, 108 +/- 32; AVF-12, 71 +/- 50 dyne/cm2), and decreased myointimal area (AVF-4, 1.18 +/- 0.26; AVF-12, 1.90 +/- 0.55 mm2). The addition of outflow obstruction to AVFs (AVFobs) resulted in elevated pressure (48 +/- 2 mm Hg), decreased flow (17 +/- 4 ml/min), larger luminal area (8.71 +/- 2.31 mm2), elevated wall tension (10.3 +/- 1.7 x 10(3) dyne/cm), and a degree of myointimal thickening approaching that of vein grafts (3.79 +/- 0.66 mm2).(ABSTRACT TRUNCATED AT 400 WORDS)
Conclusions:Due to the collateral artery network, CMI is a relatively uncommon condition despite the prevalence of mesenteric atherosclerosis. Open surgical revascularization is the most common treatment modality for CMI. Our standard approach is a supra-celiac antegrade approach with a bifurcated PTFE graft targeting the SMA and a branch of the celiac artery, usually the hepatic artery. These distal sites were poor for anastomoses in this case and instead we focused on the large meandering mesenteric artery as a suitable target. The meandering mesenteric artery (of Moskowitz) connects the middle colic artery to the left colic artery. Both the size and function as a collateral between the SMA and IMA make it a possible receiving vessel for a bypass graft when the traditional vessels are unsuitable. The successful resolution of the patient's symptoms indicates that this bypass configuration may be useful as an alternative solution to difficult cases of revascularization for CMI.
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