The impact of atherosclerosis and vascular collagen on energy-based vessel sealing.

BACKGROUND: Bipolar energy ligation of vessels in surgery is common. Although rare, serious failures occur. Atherosclerosis may contribute to seal failures by altering vascular compressibility and collagen content; however, no data exist. MATERIALS AND METHODS: Femoral and iliac arteries of six Yucatan swine with an identified genetic locus predisposing them to atherosclerosis were denuded with a Fogarty catheter. Animals were fed a high-fat diet for 28 wk. A Yorkshire pig was used as a normal control and fed a standard diet. At 28 wk, arteries were measured for their diameters, sealed, and divided in vivo with LigaSure. The sealed artery sections were excised and subjected to burst pressure testing. Half of the seal distal to the aorta was kept intact for histology and collagen and elastin quantification. A multiple linear regression model was used to assess variables contributing to burst pressure. Covariates included were vessel diameter, degree of atherosclerosis, and collagen content. RESULTS: Experimental animals were hypercholesterolemic. Atherosclerosis occurred in 90% of seals in induced animals, with severe atherosclerosis in 62% of seals. There was site-selective deposition of atherosclerotic plaques in larger diameter iliac vessels. A model including collagen and size best predicted burst pressure. Every 10-U increase in collagen resulted in 15% increase in burst pressure (95% confidence interval = 0.2%-32%, P = 0.047, R(2) = 0.36). Atherosclerosis was unrelated to burst pressure controlling for collagen and size. CONCLUSIONS: Collagen and size provide the best model fit for predicting burst pressure. Quantitative research in human vasculature is warranted to better understand the influence of atherosclerosis and collagen content on seal failures.

Role of TGF-ß1/Smad3 signaling pathway in secretion of type I and III collagen by vascular smooth muscle cells of rats undergoing balloon injury.

Antisense Smad3 adenoviral vectors were used to transfect vascular smooth muscle cells (VSMCs) from rats with balloon injury or infused into the rat balloon-catheter injured carotid arteries, and the role of TGF-ß1/Smad3 signaling pathway in the secretion of type I and III collagen by VSMCs following balloon injury was investigated. Antisense Smad3 adenoviral vectors were used to transfect these VSMCs (antisense Smad3 group). A total 90 rats were randomly assigned into blank control group, experiment group, negative control group. In the in vitro study, the expression of type I and III collagen was markedly reduced in the antisense Smad3 group when compared with the control groups (P < 0.05). In the in vivo study, the expression of type I and III collagen was significantly lower than that in the negative control group at 3 days, 1 week and 2 weeks after injury (P < 0.05). At 2 weeks and 3 months after injury, the lumen area in the antisense Smad3 group was markedly increased but the intimal area dramatically reduced when compared with the negative control (P < 0.05). We conclude that transfection of VSMCs with antisense Smad3 can reduce the secretion of type I and III collagen which then inhibit intimal hyperplasia.

Does routine completion angiogram during embolectomy for acute upper-limb ischemia improve outcomes?

BACKGROUND: Since 1963, Fogarty balloon catheter thromboembolectomy is usually adopted as the gold standard treatment for acute limb ischemia. As the success of the procedure depends on complete removal of all thromboembolic material, intraoperative arteriography can be used after arterial thromboembolectomy as a guide for extension of the procedure. It is still a matter of debate whether intraoperative angiography should be routinely performed in all cases or only in selected cases, depending on intraoperative findings, when the surgeon suspects an incomplete disobstruction. Most published evidence derives from analysis of lower-limb thromboembolectomies. The aim of our retrospective study was to elucidate the value of routine completion angiogram in acute arterial embolism of the upper limb. METHODS: Clinical and demographic data of 100 patients with acute embolic upper-limb ischemia were prospectively recorded during an 18-year period in a central hospital vascular unit setting. The relevance of intraoperative angiography was retrospectively analyzed. The procedures were divided into two groups: group A, when intraoperative angiography was performed in selected cases (selective angiography); and group B, when angiography was performed as a routine procedure in all cases (routine angiography). All factors associated with reocclusion and mortality were investigated to produce meaningful information that could assist the surgeon to predict outcomes. RESULTS: Cumulative reocclusion and mortality rates at 24 months were 14.0% and 70.0%, respectively. After upper-limb arterial embolectomy, the rate of extension of the procedure was significantly higher in group B than in group A (26.0% vs. 4.0%, P = 0.002). At 24 months after embolectomy, group B resulted in a lower incidence of reocclusion compared with group A (12.0% vs. 2.0%, P = 0.05), whereas there was no statistical difference between the two groups in terms of mortality (P > 0.05). On univariate analysis, the factor associated with increased 2-year reocclusion rate was only the avoidance of completion angiography, although it lost some of its predictive value on multivariate analysis. Factors associated with increased 2-year mortality rate on univariate analysis included age >80 years, diabetes mellitus [DM], and antiplatelet drug use. Only DM was significantly associated on multivariate analysis. CONCLUSION: Routine use of intraoperative angiography influences outcome after embolectomy for upper-limb acute arterial occlusion. Routine use of intraoperative angiography, compared with selective use, results in a higher rate of extension of the procedure for residual lesion and in a lower rate of reocclusion at 24 months. In prevention of reocclusion, completion angiogram has a hazard ratio of 5.44 on multivariate analysis. Postoperative late mortality is mainly affected by old age and DM.