Written last year by Dr R Fogoros - over in About.com - cardiology/heart disease. Of course, bypass and valve replacement are two different animals, as often mentioned in Vr. Dr Rich mentions only bypass, but heart/lung machine is a heart/lung machine, right? It's an enlightening article. Dr Rich is an EP, author, teacher, lecturer, etc. etc. You can go check him out, if you like.
Pump Head: Mental impairment after bypass surgery
By DrRich
A study from Duke University, published in the New England Journal of Medicine in February, 2001, confirms what many doctors have suspected, but have been reluctant to discuss with their patients: A substantial proportion of patients after coronary artery bypass surgery experience measurable impairment in their mental capabilities. In the surgeons? locker room, this phenomenon (not publicized for obvious reasons) has been referred to as "pump head."
In the Duke study, 261 patients having bypass surgery were tested for their cognitive capacity (i.e. mental ability) at four different times: before surgery, six weeks, six months, and five years after bypass surgery. Patients were deemed to have significant impairment if they had a 20% decrease in test scores.
This study had three major findings
1) Cognitive impairment does indeed occur after bypass surgery. This study should move the existence of this phenomenon from the realm of locker room speculation to the realm of fact.
2) The incidence of cognitive impairment was greater than most doctors would have predicted. In this study, 42% of patients had at least a 20% drop in test scores after surgery.
3) The impairment was not temporary, as many doctors have claimed (or at least hoped). The decrease in cognitive capacity persisted for 5 years.
The mental impairment was not due to the patients' age (which averaged 61). The results from the Duke study were compared to results from a similar study among patients of the same age who did not have bypass surgery. The decline in mental capacity in those who had bypass surgery was 2 -3 times higher over five years than in patients who did not have surgery.
The authors could not say what, exactly, caused the impairment in mental capacity. The most common speculation is that the mental changes are due to the showering of the brain with tiny particles (microemboli) related to the use of the bypass pump (the heart/lung machine, that oxygenates and pumps the blood while the heart is stopped during surgery.)
If this is the case, then newer surgical techniques such as ?beating heart surgery? (in which the bypass pump is not used) should help to minimize the problem. The Duke study was completed prior to the use of such procedures.
But there are other possible causes for mental impairment, including the ?trauma? of surgery (any surgery) and general anesthesia in patients whose vascular disease is almost never limited to the heart, and the breaking loose of fatty deposits from the aorta when sewing the bypass vessel to the aorta.
What will doctors think about this study?
Doctors can be expected to react to the Duke study with mixed feelings. Doctors generally consider themselves scientists, so anything that advances medical knowledge is something they feel they should embrace. However, this is a tough one.
There will be two general types of responses to this study among doctors.
Group A. While the Duke study was extremely well designed (and so it will be difficult to attack it on procedural grounds), voices are already being raised expressing dismay that patients might get the wrong impression from this study. You will almost certainly hear 3 major arguments from these doctors:
1) Cognitive impairment happens, but 42% is way too high. In our hospital, the risk is much lower.
2) This study was done on patients operated on at least 5 years ago, and our surgical techniques have improved a lot since then.
3) Publicizing this study will frighten patients away from having bypass surgery, surgery that saves thousands of lives every year. So let?s accept the data and work to improve the problem, but let?s not make a big deal about it, lest we frighten our patients into making bad decisions.
Group B. Other doctors will take the study at face value, and like the doctors from Group A will work to come up with solutions to the problem. But in the meantime, when deciding whether to recommend bypass surgery to a patient, these doctors will factor a 42% risk of some degree of cognitive impairment into the equation. And they will make sure their patients are aware of all the risks.
What should patients think about this study?
Choose your doctor from Group B. When making major decisions ? such as whether or not to have a major procedure like coronary artery bypass grafting ? you want a doctor who will take into account all the potential risks and benefits.
The Duke study is the best information available right now, and must be taken into account. So when considering bypass surgery, make sure you have the answers to the following questions:
- Is the surgery likely to prolong my survival, or is it being done electively, simply to relieve symptoms?
- Are there any other viable alternatives, such as medication, angioplasty, or stenting? (This question is becoming particularly relevant, with stent technology advancing as rapidly as it is.)
- If I must have bypass surgery, is there any reason I can?t have some form of minimally invasive surgery where the bypass pump is avoided? (While it is not proven that the bypass pump causes the cognitive problem, it does seem to be the leading suspect at this point.)
If you do need to have bypass surgery, keep in mind that the majority of patients in the Duke Study had no significant deterioration their mental capacity, and further, of the ones who did, many never noticed it in their day-to-day lives.
Nonetheless, if you are told you ought to have bypass surgery, unless it is vital that bypass surgery be performed immediately, the Duke study ought to provide one more reason to seek a second opinion before choosing this option.
