Plasma homocysteine measurements after carotid artery manipulation and clamping in a rat CEA model

Intravascular application of electrocautery in a rabbit model of abdominal aortic endarterectomy

Effective therapies for preventing perioperative complications such as thrombosis and inflammation after coronary endarterectomy (CE) are lacking. Electrocoagulation electrotomes have been routinely used in surgery for their cutting, clotting, and hemostatic properties. As strong flattening tools, their electrocautery function may prevent mechanical intimal-adventitial injury to arterial circulation and attenuate stenosis. The present study investigated the effects of intravascular application of electrocautery on ameliorating inflammation and thrombosis in a rabbit model of abdominal aortic endarterectomy. New Zealand rabbits were randomly divided into the sham, control (endarterectomy), and study (endarterectomy + electrocautery) groups with 10 in each group. Abdominal aortas were partially blocked and intima was removed. Electrocautery was performed with an electrocoagulation electrotome through the entire blocked vessel lumen. Vascular ultrasound parameters, molecular biological and histological characteristics of the abdominal aorta including vascular diameter, blood flow velocity, serum interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) levels, and apoptosis rate of vascular endothelial cells (ECs) were evaluated postoperatively by vascular Doppler ultrasound, ELISA, real-time RT-PCR, flow cytometry, and immunofluorescence at various time points. Compared with the endarterectomy + electrocautery group, the isolated endarterectomy group had significantly increased levels and gene expression of TNF-α and IL-6 (P<0.05), and rates of apoptosis of vascular ECs (P<0.05), with gradual vascular stenosis and decreased blood flow velocity. In conclusion, intravascular application of electrocautery has favorable short-term effects on the abdominal aorta and can reduce inflammation in a rabbit model of abdominal aorta endarterectomy. Long-term anti-inflammatory and anti-thrombotic effects on arterial remodeling and the clinical value of electrocautery in CE remain to be determined.

Pravastatin and Clopidogrel Combined Inhibit Intimal Hyperplasia in a Rat Carotid Endarterectomy Model

Intimal hyperplasia, resulting from a complex cascade of events involving platelets, leukocytes, and smooth muscle cells, may be inhibited by the HMG-CoA reductase inhibitor pravastatin, which demonstrates inhibition of platelet activity and leukocyte adhesion and may be associated with inhibition of vascular smooth muscle cell proliferation and migration. Clopidogrel, an adenosine diphosphate (ADP) receptor inhibitor, was shown to decrease platelet activity and aggregation but not intimal hyperplasia (IH). We postulated that the combination of both pravastatin and clopidogrel would significantly decrease IH in a rat carotid endarterectomy model. Male Sprague-Dawley rats (n = 18) divided by treatment regimen underwent treatment for 2 weeks both before and after an open carotid endarterectomy. Serum collected at the time of harvest was measured for C-reactive protein (CRP), platelet activity, and total serum cholesterol; carotid arteries were removed and processed for IH determination. Control rats (n = 7) received oral vehicle daily before and following endarterectomy. Pravastatin-alone rats (n = 6) received oral pravastatin (10 mg/kg/day) before and after endarterectomy. Pravastatin plus clopidogrel rats (n = 5) received oral pravastatin (10 mg/kg/day) plus a preendarterectomy bolus of oral clopidogrel (4.3 mg/kg) before endarterectomy and resumed pravastatin (10 mg/kg/day) plus oral clopidogrel (1 mg/kg/day) postendarterectomy. Pravastatin alone and pravastatin plus clopidogrel significantly decreased CRP compared to controls (120.2 ±11.2 and 134.1 ±9.9 vs 191.1 ±9.2 µg/mL, respectively p = 0.003 and p = 0.0024). CRP levels were not different between pravastatin alone and pravastatin plus clopidogrel (p = 0.35). Platelet activity was significantly decreased by pravastatin alone and pravastatin plus clopidogrel in comparison to controls (7.3 ±2.2 and 6.6 ±2.8 vs 19.2 ±6.1 platelet reactive units (PRU), respectively p = 0.048 and p = 0.045). No significant difference was noted in platelet activity between pravastatin alone and pravastatin plus clopidogrel (p = 0.89). Pravastatin plus clopidogrel significantly reduced serum cholesterol compared to control and pravastatin alone (84.0 ±6.6 vs 110.4 ±7.4 and 117.0 ±8.8 mg/dL, respectively p = 0.03 and p = 0.01). Pravastatin alone did not decrease serum cholesterol compared to controls (p = 0.54). IH was not reduced by pravastatin alone compared to controls (p = 0.61) but was significantly decreased by pravastatin plus clopidogrel in comparison to control and pravastatin alone (3.0 ±1.1 vs 46.3 ±13.7 and 37.4 ±14.6% luminal stenosis, respectively p = 0.01 and p = 0.05). Pravastatin plus clopidogrel significantly decreased CRP, platelet activity, total serum cholesterol, and IH while pravastatin alone decreased only CRP and platelet activity. Intimal hyperplasia reduction may therefore be dependent on other contributors, possibly growth factors, cytokines, and oxidative stress. The combination of pravastatin plus clopidogrel may have synergistic or even additional inhibitory effects on IH. Pravastatin plus clopidogrel was effective in decreasing IH in a rat carotid endarterectomy model and may prove a useful therapy for IH reduction in the clinical setting.

Estrogen replacement attenuates exaggerated neointimal hyperplasia following carotid endarterectomy in rats

BACKGROUND

To investigate whether estrogen may attenuate neointima formation in hyperhomocysteinemic rat carotid endarterectomy.

METHODS

Rats were divided into 6 groups: ovariectomized estradiol-treated homocysteine or chow; ovariectomized placebo-treated homocysteine or chow; intact placebo-treated homocysteine or chow. Chow served as controls while homocysteine served as exaggerated intimal hyperplasia. Prior to endarterectomy, rats were implanted with estradiol mini-pump or placebo, diets given 2 weeks before and after surgery. Homocysteine, estrogen, and neointimal hyperplasia were determined.

RESULTS

Homocysteine was elevated in homocysteine groups versus controls except in estradiol-treated group. Intimal hyperplasia increased in placebo-treated ovariectomized homocysteine versus intact group. Exaggerated intimal hyperplasia in placebo-treated ovariectomized homocysteine was reduced by estrogen and so was homocysteine. Estrogen replacement in ovariectomized homocysteine group reduced intimal hyperplasia to that of intact or ovariectomized controls.

CONCLUSION

Estradiol treatment in this ovariectomized hyperhomocysteinemia carotid endarterectomy and resultant attenuation of homocysteine and neointima may have relevance to the beneficial effects of estrogen on hyperplastic response.

The effects of acarbose treatment on intimal hyperplasia in a rat carotid endarterectomy model of diet-induced insulin resistance

BACKGROUND

Increased carotid restenosis due to revascularization therapy is associated with insulin resistance. We hypothesize that glucose control using acarbose may attenuate intimal hyperplasia in rat carotid endarterectomy model of diet-induced insulin resistance.

METHODS

Rats were fed low-fat complex carbohydrate (control) or high-fat sucrose (insulin resistance) for 4 months. Three days preoperatively, some high-fat-sucrose rats were on acarbose, remainder of the rats received placebo. Rat carotids were assessed with duplex pre-and postoperatively. Acarbose and placebo continued for 2 weeks. Glucose, insulin, blood flow velocities and intimal hyperplasia were determined.

RESULTS

High-fat sucrose plus acarbose attenuated intimal hyperplasia. Post-drug high-fat sucrose glucose decreased. Blood flow velocities postoperatively elevated above baseline. High-fat sucrose increased blood flow velocities postoperatively, which was attenuated with acarbose.

CONCLUSION

Glucose control by acarbose in rat carotid endarterectomy model of diet-induced insulin resistance resulted in attenuation of intimal hyperplasia.

Homocysteine and Early Re-stenosis after Carotid Eversion Endarterectomy

BACKGROUND

Homocysteine (Hcy) appears to be involved in the development of intimal hyperplasia and arterial thrombosis. The purpose of this study was to evaluate the association of plasma Hcy with early re-stenosis following carotid eversion endarterectomy.

PATIENTS AND METHODS

Of 398 consecutive patients, 363 were included in this study. 62% of patients had symptomatic internal carotid artery (ICA) stenosis. Patients had preoperative assessment of Hcy and other well established atherosclerosis risk factors. Intraoperatively, completion angiography was performed in 2 planes. Patients had clinical, Hcy and duplex follow up at 1, 3, 18 and 36 months postoperatively.

RESULTS

Complete follow up data were available for 312 patients. Five patients suffered from strokes and 2 patients died during the peri-operative period (combined stroke and death rate of 2%). Mean follow up was 26+/-5 months (range 17 to 36 months). Seventeen and six patients (5.5%) developed a 50-69% and >70% re-stenosis, respectively. Serum creatinine was significantly higher in patients with early re-stenosis, occlusion or stroke after CEA (P=0.043). High grade re-stenosis, occlusion and stroke ipsilateral to the operated side (17 patients) was associated with HbA1C and creatinine (P=0.043 and 0.046, respectively) but not Hcy.

CONCLUSION

While Hcy is a recognized independent risk factor for atherothrombosis, our study suggests that there is no association of Hcy with early re-stenosis after eversion endarterectomy.

Carotid Endarterectomy Under Local Anaesthesia does not Increase Plasma Homocysteine Concentration

INTRODUCTION

The purpose of this cohort study was to evaluate the effect of carotid endarterectomy under local anaesthesia on homocysteine (Hcy) concentrations.

PATIENTS AND METHODS

Of 100 patients with internal carotid artery (ICA) stenosis >70%, the complete data set was available for 91 patients (39 asymptomatic and 52 symptomatic). All patients underwent eversion endarterectomy of the ICA under regional anaesthesia.

RESULTS

Thirty-two percent of the examined patients had a total Hcy above 15 micromol/l. The mean Hcy levels preoperatively were 13.9+/-4.8 micromol/l. The Hcy levels on day 5 were 13.1+/-5.0 micromol/l and after 6 months 14.0+/-5.8 micromol/l. There was no significant change during follow-up. No intraoperative strokes and deaths were observed and during the 6 months follow-up no recurrent strokes, TIAs or deaths occurred.

CONCLUSION

Patients undergoing carotid endarterectomy under regional anaesthesia do not have an increase in total Hcy postoperatively. This finding is in contrast to results from cardiac surgery and carotid endarterectomy in a recently published animal study, both performing surgery under general anaesthesia.