Pump Head -- Is it for Real?

Yes - though it may not be caused by the "pump"

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Back in 2001, a study from Duke University showed that more than 40% of patients having coronary artery bypass grafting (CABG) experienced a measurable decrease in mental capacity after surgery, which persisted for up to five years. This cognitive decrease after CABG has been called "pump head," because doctors speculated that perhaps the heart/lung machine (the "pump") that is used during CABG was the culprit.

Subsequently, however, studies comparing outcomes in patients having typical "on-pump" CABG with those having minimally invasive bypass procedures (which do not require the heart/lung machine) did not show any reduction in "pump head" with the minimally invasive surgery, that is, with "off-pump" surgery. So the bypass pump itself may not be the culprit - or at least, not the only culprit.

More recent studies have now shown that long-term cognitive decline in patients with coronary artery disease CAD occurs at about the same rate, no matter what therapy they receive. A study conducted at Johns Hopkins compared the outcomes in 152 patients having typical on-pump CABG surgery with 75 patients had minimally invasive off-pump procedures, and 99 patients did not have any bypass surgery at all. All the patients had baseline cognitive testing, which was then repeated periodically for six years.  The investigators found that all three groups of patients with CAD had the same average reduction in cognitive function over the duration of the study, regardless of the type of therapy they received.

The authors concluded that the long-term cognitive decline often seen after bypass surgery is apparently not due to the surgery at all, but instead to the patient's underlying vascular disease. Apparently, the authors suggest, atherosclerosis that causes CAD is also causing a certain degree of reduced blood flow to the brain, and a gradual reduction in mental capacity.

What Does This New Information Mean?

Some cardiovascular surgeons, who had been quite distressed over the results of the original Duke study, now claim to be vindicated by the Johns Hopkins study. "It's not us," they say, "it's that nasty atherosclerosis! Pump head doesn't even exist."

Whether the pump itself causes the problem (which actually hasn't been proven or disproven), and whether long-term cognitive decline occurs at the same rate in patients with CAD even if CABG is not performed, one stubborn fact remains: After CABG, a large proportion of patients will experience at least a temporary significant reduction in mental capacity, lasting at least up to several months. In addition, the people who experience these transient changes in mental function after surgery appear to be the very ones who, once they recover, are at particular risk for the kind of long-term deterioration in cognitive function that was measured in the Johns Hopkins study.

Furthermore, evidence now exists that formal cognitive training following CABG can significantly diminish post-operative cognitive decline.

Unfortunately, it appears that relatively few places have instituted such cognitive training. (If your doctor is recommending CABG, this is something you ought to ask about.) 

Possibly the most important take-away here is that atherosclerosis is not "merely" a disease that can block the coronary arteries, or that can be "fixed" by surgery, stenting, or any other local procedure. Rather, atherosclerosis is a chronic, progressive vascular disease that can affect several important organs in the body, including the brain. Anyone who has atherosclerosis, or who is at increased risk for atherosclerosis, needs to do everything they can to reduce the risk factors that accelerate this chronic, progressive disease.

Sources:

Newman MF, Kirchner JL, Phillips-Bute B, et al. Longitudinal assessment of neurocognitive function after coronary-artery bypass surgery. N Engl J Med 2001; 344:395-402.

Selnes OA, Grega MA, Bailey MM, et al. Do management strategies for coronary artery disease influence 6-year cognitive outcomes? Ann Thorac Surg 2009; 88:445-454.

de Tournay-Jetté E, Dupuis G, Denault A, et al. The benefits of cognitive training after a coronary artery bypass graft surgery. J Behav Med 2012; 35:557-568. 22068879

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