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Bypass surgery and brain damage

BALTIMORE, MARYLAND. Bypass surgery (coronary artery bypass grafting) is associated with a significant risk of subsequent stroke and brain damage (encephalopathy). Researchers at the Johns Hopkins University report a stroke rate of 2.7 per cent and an encephalopathy rate of 6.9 per cent in 2711 patients who underwent bypass surgery during the period January 1, 1997 to December 31, 2000. Patients with encephalopathy (delirium, confusion, coma, and seizures) had an average hospital stay of 15.2 days and a mortality of 7.5 per cent. Patients with stroke stayed in the hospital for an average of 17.5 days and had a mortality of 22 per cent. Patients with neither of these conditions had an average stay of 6.6 days and a mortality of 1.4 per cent.

The researchers attempted to correlate the pre-operation state of the patients with their risk of surgery- induced encephalopathy or stroke. They found that the risk of encephalopathy increased with age, a history of past stroke, and the presence of hypertension, diabetes or carotid bruit (carotid artery blockage). The risk of stroke could be predicted by a history of past stroke, hypertension and diabetes. Time spent on the cardiopulmonary bypass machine during the operation was found to be another important variable. The risk of encephalopathy or stroke increased by 30 to 50 per cent for each additional 30 minutes spent on the machine.

The researchers conclude that their models may be useful when discussing the risk of bypass surgery with patients and their families. They also suggest that surgery without a bypass pump may be an option for high-risk patients.
McKhann, Guy M., et al. Encephalopathy and stroke after coronary artery bypass grafting. Archives of Neurology, Vol. 58, September 2002, pp. 1422-28

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