Maintaining carotid flow by shunting during carotid endarterectomy diminishes the inflammatory response mediating ischaemic brain injury

Objectives: to assess whether shunting during carotid reconstruction affects the release of inflammatory mediators from the ipsilateral hemisphere. Materials and methods: a catheter was placed in the ipsilateral jugular bulb during carotid endarterectomy (CEA) in 20 patients. Eight patients with ICBP (internal carotid backpressure) < 40 mmHg received a shunt during CEA and 12 patients with ICBP > 40 mmHg were operated upon without a shunt. Four patients with a carotid body tumour were used as controls. Blood was taken from the catheter as well as from the radial artery before clamping, 5, 15, 30 min after clamping and 5 min after declamping. The oxygen extraction (AVO₂) was calculated. Plasma concentrations of interleukin- 1β (IL-1β), phospholipase A₂ (PLA₂), thromboxane B₂ (TXB₂), 6-keto-prostaglandin F(1α) (6-keto-PGF(1α)) and prostaglandin E₂ (PGE₂) were measured by enzyme-linked immunosorbent assay (ELISA) technique. Results: all patients had a normal postoperative course except for one patient in the no-shunt group, who suffered a stroke 1 h later due to occlusion of the endarterectomy site. The AVO₂ extraction increased during clamping in patients operated upon without a shunt (p < 0.05). This increase was partly recovered to pre-clamp levels 5 min after reperfusion. The extraction remained stable in the non-shunted patients and the control group. The increased extraction in the non-shunted group correlated with increased levels of IL-1β during clamping (p < 0.05) and reperfusion (p < 0.01). PLA,also increased during reperfusion in the non-shunted group (p < 0.05). An increased ratio between TXB₂ and 6-keto-PGF(1α) was noted during clamping (p < 0.05) and further increased during reperfusion. The levels of PGE₂ remained stable in both CEA groups. The PLA₂ levels, as well as TXB₂, 6-keto-PGF(1α) and PGE₂ levels, remained unchanged during the procedure in the control group. Conclusions: there is a metabolic response to carotid cross-clamping when no shunt is used. However, the clinical significance of this is unclear, since there were no intraoperative strokes.