When arteries become blocked, coronary artery bypass graft (CABG) surgery often is the treatment of choice. Since its introduction in the 1950s, the number of patients undergoing the procedure has grown, and today it is one of the most common surgical procedures in the US, with about a half million procedures performed yearly.
CABG surgery can improve quality of life and, in many cases, it’s necessary for survival—but it is not without risk. A recent report in the online journal MedLink Neurology focused on one of the most common neurological complications of heart surgery—cognitive impairment, which includes disturbances in learning, memory, attention, concentration and speed of mental responses. “Recovering cognition may take six weeks or more,” says Harlan Krumholz, MD, professor of medicine and epidemiology and public health (cardiology) at Yale University School of Medicine. He emphasizes that many patients do ultimately recover completely.
Even so, there is a high risk for cognitive decline during the five years after CABG surgery. While much of the variance depends on the patient’s condition before surgery, by and large, most such problems have been attributed to use of the bypass pump, which diverts blood from the heart and creates turbulence in the blood during the course of the surgery. This can result in emboli (blood clots or bubbles or plaque) and/or cause preexisting ones to dislodge. These may then flow up the carotid artery and into the blood vessels in the brain, potentially causing stroke. Some studies suggest this risk is reduced with off-pump CABG surgery, but according to Dr. Krumholz, the data is unclear on this issue.
Emboli can be especially dangerous at particular times. Most preexisting emboli are dislodged into the bloodstream immediately after releasing the aortic clamp at the end of surgery, when the force of blood coursing through the aorta can be likened to water flowing full-force through a garden hose. Emboli can also be formed as a result of arrhythmia (disruption in the normal heart rhythm), which can occur during or after surgery.
Another potential cause of cognitive problems, unrelated to emboli, is the chemical residue of anesthesia, of which the body must clear itself after surgery, Dr. Krumholz said. Having impaired circulation, which of course is common in heart patients, means that this isn’t likely to be done efficiently or easily, and the longer the anesthesia chemicals and their by-products remain in the blood, the more likely they are to cross the blood-brain barrier and impair cognition. According to Daily Health News contributing medical editor Andrew L. Rubman, ND, “when anesthesia is incompletely processed, it’s more likely to affect the central nervous system over the longer term.”
Reiterating that many of the people who require heart surgery have vascular disease, Dr. Krumholz told me that it can be tough to tease out whether subsequent cognitive impairment is a result of the preexisting condition or the surgery. He said that even though age increases risk for post-op neurological problems, the reality is that CABG is often performed on patients who are quite old and quite sick. Vascular disease—including high blood pressure, diabetes, a blocked carotid artery, significant plaque in the aorta, kidney problems, a clot in the heart or prior strokes—boosts risk as well, exponentially. Other factors, including the length of time that a patient is on a bypass pump and whether or not a particular kind (an intra-aortic balloon pump, which is the most widely used mechanical circulatory support) is used contributes to risk for cognitive deficit as well.
“There are several ways that you can help your body to be less affected by the challenges of the surgery,” says Dr. Rubman, noting that “the more prepared you are, the less likely that you’ll develop either short- or long-term cognitive deficiency.”
To prepare for CABG, Dr. Rubman suggests starting as soon as possible to take…
Dr. Rubman emphasizes that dosages and timing for these supplements must be individualized and should be done with expert oversight. It is best if your treatment team includes a naturopathic physician who specializes in diet, nutrition and supplement therapy.
For people who have already had CABG: If you weren’t able to take these supplements before surgery, it’s not too late to improve your outcome, Dr. Rubman says. Start right away, and remember that it is absolutely vital that your cardiologist and surgeon be involved, as these interventions are not only not appropriate for all patients, but may be harmful to some.
According to Dr. Krumholz, technological advances in CABG surgery have been “huge” and surgeons are also now able to utilize strategies to reduce the risk of stroke, including filters that prevent emboli from recirculating in the blood. “CABG surgery can be accomplished with excellent results, but the expertise of the surgical team is critical, and the institution you choose should have extensive experience with this type of surgery,” he said.
