Techniques for the percutaneous treatment of acute arterial occlusion.

There are many modalities utilized in the treatment of acute arterial occlusions. The purpose of this report will be to review the various studies defining percutaneous chemical thrombolysis, mechanical thrombectomy, and combination therapies. A clinical paradigm for acute limb ischemia will be defined, and a detailed description of techniques utilized in the above percutaneous interventions will be outlined.

Dual contrast enhanced magnetic resonance imaging of the liver with superparamagnetic iron oxide followed by gadolinium for lesion detection and characterization.

AIM: Iron oxide contrast agents are useful for lesion detection, and extracellular gadolinium chelates are advocated for lesion characterization. We undertook a study to determine if dual contrast enhanced liver imaging with sequential use of ferumoxides particles and gadolinium (Gd)-DTPA can be performed in the same imaging protocol. MATERIALS AND METHODS: Sixteen patients underwent dual contrast magnetic resonance imaging (MRI) of the liver for evaluation of known/suspected focal lesions which included, metastases (n = 5), hepatocellular carcinoma (HCC;n = 3), cholangiocharcinoma(n = 1) and focal nodular hyperplasia (FNH;n = 3). Pre- and post-iron oxide T1-weighted gradient recalled echo (GRE) and T2-weighted fast spin echo (FSE) sequences were obtained, followed by post-Gd-DTPA (0.1 mmol/kg) multi-phase dynamic T1-weighted out-of-phase GRE imaging. Images were analysed in a blinded fashion by three experts using a three-point scoring system for lesion conspicuity on pre- and post-iron oxide T1 images as well as for reader's confidence in characterizing liver lesions on post Gd-DTPA T1 images. RESULTS: No statistically significant difference in lesion conspicuity was observed on pre- and post-iron oxide T1-GRE images in this small study cohort. The presence of iron oxide did not appreciably diminish image quality of post-gadolinium sequences and did not prevent characterization of liver lesions. CONCLUSION: Our results suggest that characterization of focal liver lesion with Gd-enhanced liver MRI is still possible following iron oxide enhanced imaging.Kubaska, S.et al. (2001). Clinical Radiology, 56, 410-415

The effect of growth factors, cytokines, and extracellular matrix proteins on fibronectin production in human vascular smooth muscle cells.

PURPOSE: Although 60% to 80% of the mature intimal hyperplastic plaque is composed of extracellular matrix (ECM) proteins, little is known about the factors that stimulate smooth muscle cells (SMCs) to produce these proteins. A major component of the ECM protein is fibronectin. Thus we studied fibronectin production and its response to various growth factors, cytokines, and other ECM proteins that are released at the time of vascular injury. METHODS: Quiescent cultured human SMCs were stimulated for varying intervals with increasing concentrations of agonist. Fibronectin in the cell medium was assayed by immunoblotting with a fibronectin-specific antibody. RESULTS: After 72 hours of stimulation, transforming growth factor-beta (10 ng/mL) had the most profound effect on fibronectin production (9.6- +/- 2.1-fold; P <.05), followed by epidermal growth factor (100 ng/mL; 5.0- +/- 0.1-fold; P <.05, for both). Surprisingly, the platelet-derived growth factors (AA, AB, and BB) and fibroblast growth factor did not stimulate fibronectin production. Among the matrix proteins studied, only collagen type I (20 microg/mL) stimulated fibronectin production (1.9- +/- 0.1-fold; P <.05), whereas collagen type IV and laminin had no effect. The contractile protein angiotensin II (100 ng/mL) was a weak stimulant of fibronectin (1.6- +/- 0.2-fold; P <.05). Time course studies of fibronectin production up to 72 hours revealed kinetics that varied with each agonist. Transforming growth factor-beta stimulated significant early production of fibronectin, whereas fibronectin production in response to epidermal growth factor and collagen type I was initially modest but increased with time. The effect of angiotensin II did not become evident until 72 hours. CONCLUSION: Cytokines, growth factors, and matrix proteins have varying quantitative effects on ECM protein production by human vascular SMCs. Knowledge of the factors that influence ECM protein production may allow for the design of specific inhibitors that can prevent intimal hyperplasia.

Bilateral carotid endarterectomy during the same hospital admission.

The efficacy of carotid endarterectomy for the prevention of strokes has been well demonstrated in recent multicenter randomized trials. However, patients presenting with bilateral significant disease pose a difficult problem to the vascular surgeon. Currently, bilateral carotid endarterectomies are staged at varying intervals between operations, with surgeon and patient weighing the risks of waiting for surgery versus the risks of having both procedures done within a shortened interval. There are few data and no consensus on the optimal time interval between these operations. In order to evaluate the timing of carotid endarterectomies in patients with severe bilateral disease, the authors reviewed their experience with patients who had bilateral procedures performed during one hospitalization. Over the past 5 years, they have performed 204 such carotid endarterectomies in 102 patients. Cervical block anesthesia was used in 99% (201/204) of these procedures. All patients either had symptomatic disease, > 60% stenosis or severe ulcerative plaque as defined by duplex scan and/or preoperative angiography. Symptomatic stenoses were the operative indications in 39% (80/204) of the patients; the remaining 61% (124/204) were symptom-free. The majority of patients (80%; 164/204) had their second procedure performed within 2 days of their first operation. There was no operative mortality and only one permanent neurologic defect in this group for a combined stroke mortality rate of 1%. Three patients (1.5%) had transient neurologic deficits postoperatively which completely resolved by discharge. These data show that bilateral carotid endarterectomies can be performed safely and effectively during one hospital admission with a short interprocedural interval and without an increase in mortality or morbidity.