Watershed cerebral infarction associated with perioperative hypotension.

The pathogenesis of perioperative stroke is not clear from the literature. To explore the influence of various risk factors we examined the clinical, Duplex ultrasound and computerised tomography findings of all cases suffering cerebral infarction within 24 hours of surgery in a prospective series of 358 coronary or peripheral vascular reconstructive operations. Four patients (1.1%) had cerebral infarcts within 24 hours of surgery, all associated with perioperative systolic blood pressures of less than 90 mmHg. The other significant risk factor was previous cerebral ischaemic symptoms. Haemodynamic cerebral ischaemia occurred immediately after operation in 2 of 10 cases with severe symptomatic carotid stenosis or occlusion (stroke risk 20%; 95% confidence interval 2.52%-55.61%). Two cases with mild carotid disease had cerebral infarcts in previously asymptomatic hemispheres following coronary artery bypass graft surgery. One of these had clinical and computerised tomographic evidence of cortical watershed infarction. We conclude that cerebral haemodynamics are important in perioperative stroke and that symptomatic patients with severe carotid disease may be at high risk of perioperative watershed infarction.