Neurological complications after cardiac surgery in adults

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Although the number of patients undergoing surgery for valvular and other types of heart disease has remained fairly constant, the number undergoing coronary revascularization procedures is rising. Thanks to many technological advances over the past four decades, there has been a steady fall in both the mortality and morbidity associated with these procedures. Despite this fact, neurological injury remains an important cause of postoperative morbidity and is responsible for an increasing proportion of perioperative deaths. Advancing age and atherosclerosis make the more than 800000 patients a year that undergo cardiac surgical procedures worldwide that are particularly prone to neurological morbidity. Since the introduction of cardiopulmonary bypass (CPB) in the early 1950s, the neurological sequelae of cardiac surgery have been a major concern. More recently, identification of risk factors for adverse neurological and neuropsychological outcome has allowed physical and pharmacological neuroprotective strategies to be targeted at the high-risk population.

Over the past 20 years, there has been a steady increase in the average age of patients undergoing cardiac surgery. This increase has been accompanied by a rise in both the severity of cardiac disease at the time of surgery and the reoperation rate for recurrent disease. Nevertheless, the likelihood of dying or sustaining a major complication after cardiac surgery in the late 1990s is significantly lower than in the 1950s. Not unreasonably, most patients expect to survive cardiac surgery intact, make a good functional recovery and live longer. A significant number of patients undergoing cardiac surgery will, however, suffer a perioperative complication involving the central nervous system (CNS).

Adverse neurological outcome from cardiac surgery is the result of damage to the brain, spinal cord and/or peripheral nerves. CNS injury ranges in severity from subtle changes in personality, behaviour and cognitive function to fatal brain injury - the cerebral catastrophe. A major neurological complication after otherwise successful surgery represents a devastating outcome for both the patient and their family. The social and economic impact is enormous.

The common occurrence of adverse CNS outcomes has resulted in enhanced interest in strategies for cerebral protection in cardiac surgery ranging from stratification of an at-risk population to management of aortic atherosclerosis, temperature and rewarming.