A new analysis investigates the impact of heart surgery on cognitive performance.
Almost 8 million people in the United States undergo cardiovascular surgery or other related procedures each year.
Thanks to the steady improvements made by medical science, the procedures are becoming ever safer and can give people a new lease of life.
Aware of improvements in physical health due to cardiovascular surgery, scientists know less about the cognitive impact of open heart surgery.
A recent study set out to understand precisely how heart surgery might influence the mind. In particular, the researchers were interested in heart valve surgery.
Previous studies have looked at cognitive decline following some types of heart operation, but scientists know little about the impact on this particular group of surgical patients.
Valve surgery and the mind
Each year in the U.S., around 150,000 heart valve surgeries take place. In most cases, surgeons operate to treat aortic stenosis. This is a condition where the aortic valve becomes narrowed, partially blocking blood flow from the heart to the rest of the body.
Generally, aortic stenosis occurs in people aged 65 or older. Because of the aging population, the number of cases of aortic stenosis is predicted to increase significantly over the coming decades.
As people age, their cognitive ability tends to decline, so understanding how heart surgery might further impact cognitive ability is crucial.
To investigate, the researchers pooled data from 12 existing studies. They assessed the cognitive performance of all the participants before and after surgery. In this analysis, the scientists also compared the effects of two types of valve surgery — aortic and mitral. Their findings were published recently in the Journal of the American Geriatrics Society.
The authors found that in the first month after surgery, there was a decline in cognitive ability. However, they also showed that by 6 months post-surgery, a person's thinking abilities had almost returned to normal.
In fact, some of the studies analyzed for the review suggested that cognitive ability was slightly improved 6 months after surgery, compared with before surgery.
The analysis also showed that the patients' cognitive performance responded differently depending on the type of surgery they had. Those who had surgery on the aortic valve saw more significant cognitive deficits in the first month following surgery, while those who had mitral valve surgery experienced a less significant cognitive decline.
Over the following 6 months, however, the difference in deficits steadily disappeared as the cognitive abilities of those who underwent aortic valve procedures caught up.
However, this difference might not have been due to the procedures themselves. It is possible that the differences were due to age — individuals who underwent aortic valve procedures were, on average, 9 years older than those who had mitral valve procedures.
More questions than answers
Overall, the researchers conclude that individuals who undergo heart valve surgery are likely to have reduced cognitive ability for the first few months after the procedure.
Although mental ability is likely to return to normal within 6 months, this is a matter for further research. The authors of the study note this as one of the study's shortfalls — they did not investigate cognitive performance past the 6-month point.
The authors also note that, for some of the studies they analyzed, it was not clear whether the participants had undergone previous surgery, or whether this was the first event.
Also, the researchers did not know about some other factors that might have influenced cognitive changes, such as level of education, social support, depression, blood pressure, and the severity of cardiovascular disease a person had.
The authors hope that their findings "encourage routine preoperative cognitive assessment to establish cognitive baseline and postoperative assessment to monitor trajectory."
According to the authors, it would be useful if future studies focused on the specific factors that made valve surgery patients more susceptible to cognitive decline. This could guide clinicians as they help patients and their families through the recovery process.