Mental Changes After Coronary Bypass Surgery

• What Happens During Coronary Artery Bypass Grafting?
• Mental Responses after CABG Surgery
• What You Can Do

You may be a patient, or be close to a loved one who is about to go through what is commonly called coronary bypass surgery, coronary artery bypass grafting, CABG surgery, coronary artery surgery, or a heart bypass operation. You may have heard that this operation can result in some changes in how a person thinks, feels, or acts. Some people may be concerned they will feel dull, fatigued, or heavy. This article is to aid in understanding some of the medium and long-term mental changes after coronary bypass surgery that may occur in some patients who undergo such an operation. This will help patients and their families prepare for and make necessary allowances for these changes should they occur. While mental changes after coronary bypass surgery do not happen in all people who choose to have this operation, it is only fair to understand that this is a risk that this treatment has.

What Happens During Coronary Artery Bypass Grafting?

Coronary artery bypass grafting (CABG) is an effective treatment developed to treat patients with the disease of atherosclerosis. Atherosclerosis is a disease in which damaging plaques of atheroma develop in the lining of the major arteries of the body, often due to raised cholesterol levels, high blood pressure (or hypertension) and tobacco smoking. These plaques cause narrowing and partial blockage of these vessels. In the coronary arteries – the arteries that supply the heart itself with oxygen – this may cause a pain called angina pectoris (or simply angina). If a portion of heart muscle dies off because of lack of oxygen, then this is called a myocardial infarction – commonly called a heart attack. These problems are really part of the same disease – called together coronary heart disease or (CHD). To prevent and partly treat these problems, the treatment of Coronary Artery Bypass Grafting has been developed. In this operation, a surgeon takes blood vessels from another part of the body (one that is less important than the heart) and attaches short lengths of these onto the affected coronary vessels, so that the blockage can be bypassed. This attaching is called ‘grafting’. One or more grafts may be performed in the same operation. During the operation, the patient is asleep while under general anaesthesia. The procedure is performed through a special cut called a midline incision that is made in the centre of the chest. Normally, the main function of the heart and lungs is to maintain oxygen supplies to the body through the blood – during this operation, a machine called a ‘cardiopulmonary bypass’ (or CPB machine) may be used to enrich the blood with oxygen artificially.

Mental Responses after CABG Surgery

Normally, most patients feel a little dazed after waking up from a general anaesthetic! Ever since operations began with general anaesthetics in the nineteenth century, it has been observed that after any type of operation, a significant proportion of patients wake with a confused or delirious, disoriented state. This response is very common after a wide range of operations, often lasting hours up to several days. Generally, after a full checkup, there turns out to be no seriously cause of the confusion, and therefore confusion by itself does not generally ruin a good recovery from an operation, or indicate that the operation went badly. Up to 70% of patients have been reported for some degree of confusion immediately after CABG surgery. However, for a minority of patients after CABG surgery, there are mental effects that are clearly longer than short-term confusional states. This was first observed in the 1980s and remains an area of research. These changes generally take the form of subtle but measurable changes in memory, understanding and thinking.

They most commonly occur in older men, but may occur in any person undergoing this operation. It is thought that these changes are due to very small strokes, where the brain has suffered a loss of blood flow and oxygen to a small area. At first, researchers believed the mental changes might be due to the use of the bypass machine. This is because even though the machine tries to match the role of the heart, it cannot do the job as perfectly as the heart and lungs themselves. However, researchers looked at allowing the heart to continue to be the active pump during the operation (“on-pump” surgery) so that a bypass machine was not necessary. The results of these studies show no difference between patients who had an “off-pump” surgical technique instead of an “on-pump” operation. Since the development of excellent brain imaging using MRI (Magnetic Resonance Imaging) in the 1990s, it was shown that – in the CABG patients that experienced more mental changes after surgery – there was a higher frequency of stroke damage present in the brain before the operation. Surprisingly, very often, a person denied ever having a stroke in these studies.

It is now understood that as a person ages, tissues in the brain become damaged by one – or many – very small and unnoticed areas of scarring related to mini-strokes. These are tiny events that accumulate over a lifetime – not the kind of strokes that many people are familiar with. Very few patients after CABG surgery complain of any noticeable deficit that resembles a genuine stroke. However, full neurological testing performed in a study by Duke University in the USA in 2001on 261 patients showed that 24% of patients six months after surgery had at least subtle evidence of mental loss of capacity. Whether the patients themselves had any noticeable concerns is another, very important question. Another important question is “How often do these mental changes occur in CABG operations compared with other forms of surgery?” At present, there have not been studies powerful enough to answer these important questions – they have either had too few patients or simply not set up to answer those questions. There are important ethical problems when trying to develop studies of this kind – after all, how do you decide who goes in which group? In short, there is no firm consensus on these questions, and it would be unfair to say either way. However, this has to be taken in light of the fact that this operation certainly does have benefits that are definitively known – this is a life saving operation, and many people live long and pain-free lives because of it. When balancing benefits against risks, it is important to examine how reliable each side is.

What You Can Do

Whatever the situation, a patient preparing for a CABG operation can take steps to improve the results of surgery and minimise any problems.

• Remember that depressive illness is common in this condition – be proactive about seeking treatment if depression is evident. It has been shown that untreated depression worsens the outcomes of coronary artery disease – interestingly, though, it has also been shown that improving your home life and social situation improves outcomes for cardiac patients. This can include spending time with your marital partner, or acquiring a family pet.
• Make allowances for reducing stress levels after a CABG operation for quite a long period, as stress on the brain may make confusion or any slight mental changes more difficult and apparent. Consider making adjustments to lifestyle both at work and at home which make life simpler and easier.
• It is better openly to discuss the possibility of work associates, close friends and family needing to give a little assistance and make adjustments to accommodate any mental changes. Although this may sound embarassing or awkward, sometimes the best way to be taken seriously is to look as if you treat the situation seriously.
• Attend your GP monthly for control of hypertension. Although you should discuss it with your GP, we generally say that a blood pressure below 130/85 is optimal.
• Practise sit-ups with the arms folded across the chest over a pillow – this will reduce the discomfort arising after the surgery.
• Maintain total Cholesterol below 4.0 mmol/L and a “good’ cholesterol (HDL cholesterol) above 1.0 mmol/L by diet, exercise, corrective oils and tablets.
• No smoking! Seek expert help to stop smoking if necessary. Some patients may even not be considered for heart surgery if they are continuing to smoke because the risk of operation may be excessively high.
• Careful attendance to medication instructions is important, especially any blood-thinning (anticoagulant) drugs. There may be statistically lower risks if arthritis tablets (Non-Steroidal Anti-Inflammatory Drugs or NSAIDs) are not used in heart patients, such as by substituting them for stronger slow-release opiate or narcotic tablets or centrally acting painkillers, as NSAID may pose certain risks with respect to clotting events in the body.
• If over 40, check a minimum of at least yearly for diabetes. The most accurate test if especially at risk or in doubt is to have a full glucose tolerance test performed through a GP.
• Maintain a physically active lifestyle both at work and at play. For example, to start with, go for an hour’s walk just three times a week. Don’t take the lift at work all the way and don’t waste precious time finding that empty parking bay just outside the shops or workplace – park your car half a block away and do the legwork! Your body, mind and heart will thank you for it in the long run, and you’ll be there for it!

(Article kindly contributed by Dr Pamela Bradshaw PhD, Adjunct Research Fellow, School of Population Health, University of Western Australia.)

References

1. Murkin J, Newman S, Stump D, Blumenthal A. Statement of consensus on assessment of neurobehavioral outcomes after cardiac surgery. Ann Thorac Surg 1995;59:1289-95
2. Newman M, Kirchner J, Phillips-Bute B, et al. Longitudinal assessment of neurocognitive function after coronary-artery bypass surgery. N Engl J Med 2001;344:395-402
3. van Dijk D, Jansen E, Hijman R, et al. Cognitive outcome after off-pump and on-pump coronary artery bypass graft surgery: a randomized trial. JAMA 2002;287:1405-12.
4. van Dijk D, Diephuis JC, Nierich AP, Keizer AM, Kalkman CJ. Beating heart versus conventional cardiopulmonary bypass: the octopus experience: a randomized comparison of 281 patients undergoing coronary artery bypass surgery with or without cardiopulmonary bypass. Semin Cardiothorac Vasc Anesth. 2006;10:167-70.
5. Selnes O, Grega M, Borowicz L Jr., Royall R, McKhann G, Baumgartner W. Cognitive changes with coronary artery disease: a prospective study of coronary artery bypass graft patients and non-surgical controls. Ann Thorac Surg 2003:75:1377-84
6. Goto T, Baba T, Honma T, et al. Magnetic resonance imaging findings and postoperative neurologic dysfunction in elderly patients undergoing coronary artery bypass grafting. Ann Thorac Surg 2001;72:137-42.
7. Lund C, Sundet K, Tennoe B, et al. Cerebral ischemic injury and cognitive impairment after off-pump and on-pump coronary artery bypass grafting surgery. Ann Thorac Surg 2005:80;2126-31.
8. http://www.mayoclinic.com/health/coronary-bypass-surgery/HB00022 van Dijk D, Diephuis JC, Nierich AP, Keizer AM, Kalkman CJ.