Venous Repair with Vascular Clips and Conventional Suture: A Comparative Experimental Study

Objectives:

The non-penetrating Vascular Clip System (VCS) was tested experimentally and compared with the conventional suture method on the venous system.

Materials and Methods:

In five pigs, 30 transverse venotomies were carried out in the jugular and renal veins, and vena cava. Fifteen venotomies were reconstructed using autosuture clips and 15 using the standard needle and suture method. Eight weeks later, following phlebography, the specimens were examined macro- and microscopically.

Results:

For both methods, the veins remained patent; however, significant stenosis of 8.9% (95% CI: 0.6–17.1) for the renal vein and 8.5% (95% CI: 1.2–15.7) for the vena cava occurred when the suture technique was used. The intima to media height ratio remained the same. The anastomosis time with the clips was significantly shorter ( p<0.05), while the endothelium remained intact without any hyperplasia or inflammatory changes, which are usual findings of the suture technique.

Conclusion:

Early and mid-term results show that the VCS clipped anastomotic technique seems to be effective and acceptable for venous reconstructions.

Effects of dopexamine on lipid peroxidation during aortic surgery in pigs: comparison with dopamine

OBJECTIVE

We investigated the dose-related effect of dopexamine and dopamine on free radical production and lipid peroxidation estimated by MDA measurements in an ischaemia-reperfusion model of supraceliac aortic repair.

DESIGN

Prospective, randomized, blinded experimental study.

MATERIALS

Twenty-five healthy pigs.

METHODS

All experiments were performed under general endotracheal anaesthesia. Supraceliac aortic cross clamping was performed in all pigs. The pigs were randomly assigned into five groups (n=5 in each group) and received a continuous intravenous infusion of normal saline (CTL), dopamine 2 microg kg(-1)min(-1) (dopa 2), dopamine 8 microg kg(-1)min(-1) (dopa 8), dopexamine 2 microg kg(-1)min(-1) (dopex 2), dopexamine 8 microg kg(-1)min(-1) (dopex 8). Cardiac output, mean arterial pressure, arterial blood gas analysis and blood sampling for plasma MDA measurements (to reveal lipid peroxidation) were recorded after induction of anaesthesia (baseline), 60 and 120 min after cross-clamping of aorta (ischaemia phase), and 60 and 120 min after restoration of flow (reperfusion phase).

RESULTS

Dopexamine and dopamine at 8 microgkg(-1)min(-1) reduced MDA at 60 and 120 min after reperfusion.

CONCLUSION

Dopexamine seems superior to dopamine in reducing oxygen free radicals and subsequent lipid peroxidation during reperfusion after supraceliac aortic cross clamping in pigs.

Experimental surgery in infrarenal aorta and sigmoid ischemia

AIM

Colon ischemia is a rare but serious complication in surgery of the infrarenal aorta, due to ligation of the inferior mesenteric artery and the ischemia-reperfusion syndrome. In order to investigate the degree of intestinal damage, we employed experimental surgery in pigs, applying the usual protocol for elective repair of the infrarenal aorta (AAA or Y graft).

METHODS

Three groups of pigs were operated on. In Group A (n=4, 21-25 kg, mean 22.6) a sham operation was performed. In Group B (n=6, 21-26 kg, mean 24) the infrarenal aorta was cross-clamped along with the internal and external iliac arteries and a longitudinal incision was performed in the aorta, while in Group C (n=5, 20-27 kg, mean 23.8) a Pruitt-Inahara shunt was used to allow flow from the infrarenal aorta towards the iliac arteries and the inferior mesenteric artery during cross-clamping. The duration of cross-clamping was two hours (Group B and C). In all groups we evaluated sigmoid histology after reperfusion under light microscopy.

RESULTS

The pathologic examination of the sigmoid revealed increased postischemic injuries in Group B, while the protective effect of the shunt was obvious in Group C. The tissue samples of Group B presented hyperemia, submucosal edema, dilatation of the lymph vessels and severe inflammatory infiltration of the mucosa, muscularis propria and serosa, with cells showing acute and chronic inflammatory responses. In Group C all specimens presented hyperemic vessels and a slight inflammatory reaction of mucosa. In conclusion, Group B, presented the most severe inflammatory changes, involving all layers, while in Group C congestion and slight inflammatory reactions of the mucosa were observed. In Group A, no significant changes in normal histology were observed.

CONCLUSION

The importance of these findings is evident, because in the clinical situation patients have variable degrees of arteriopathy, thus even short periods of ischemia might prove disastrous and this could occur in repair of the infarenal aorta as well as in other cases of inevitable risk, such as in surgery of the thoraco-abdominal aorta.

Oxygen free radicals in abdominal aortic surgery. An experimental study

BACKGROUND

In aortic reconstruction, intestinal and muscular ischaemia in the lower limbs occurs during cross-clamping of the aorta. After restoration of blood flow, reactive oxygen intermediates may lead to systemic injury to local or remote organs. In this study we investigated the usefulness of a shunt and vitamin E administration against the oxidant load generated in ischaemia-reperfusion phases.

METHODS

In three groups of pigs (n=16) aortic reconstruction was simulated. In Group A (n=5) clamping of the infrarenal aorta was performed for 2 hours. In Group B (n=6), during aortic cross-clamping, a shunt was used to give flow to the inferior mesenteric and internal iliac arteries. In Group C (n=5) vitamin E was administered before aortic cross-clamping. In all groups we evaluated sigmoid histology after reperfusion, while the oxidant load was estimated by measuring superoxide dismutase (SOD) activity in blood samples from portal and jugular vein.

RESULTS

Histology of the sigmoid revealed increased postischaemic injuries in Group A, while the protective effect of shunt and vitamin E was apparent in Group B and C, respectively. SOD activity was minimized in Group C.

CONCLUSIONS

Vitamin E protected the sigmoid from postischaemic injury and is responsible for the decreased levels of SOD activity.

Effect of balloon angioplasty and stenting following clips vs suture arterial stenosis: an experimental study

BACKGROUND

Comparative evaluation of balloon angioplasty following intravascular stenting after experimental stenoses caused by arterial reconstruction with vascular clips and conventional sutures.

MATERIALS AND METHODS

A total of 24 arteriotomies were carried out at the carotid and common iliac arteries of pigs following a 10 mm longitudinal arteriotomy and provocation of stenosis. Twelve of the arteries were reconstructed with vascular clips and 12 with conventional suture. Ultrasonography revealed stenosis fluctuating from 60-95% (PSV: 1.8-3.5 m/sec EDV: 1.3-1.47 m/sec PSV ratio > 3.5). After 8 weeks, following digital subtraction angiography, which revealed > 50% stenosis in all of the cases, balloon angioplasty followed by placement of intravascular stent was carried out.

RESULTS

All the angioplasties remained angiographically and macroscopically patent two months after without thrombus formation. Rupture during dilatation occurred in one of the sutured cases. Histologically no degenerative changes, necrosis or remarkable intimal thickness were observed in either method. Focal inflammatory reaction was seen in 2 sutured and in 1 clipped cases while intimal ulceration was observed in 2 sutured cases. All cases with clips presented an intact endothelial surface.

CONCLUSION

Early experimental results suggested that arterial stenosis provoked by clipped reconstruction could be managed successfully by balloon angioplasty followed by placement of intravascular stent.