Off-pump surgery offers advantages for many patients

If you have coronary artery disease in which one or more of the main blood vessels feeding your heart is blocked, you may be facing coronary artery bypass grafting (CABG) surgery. In the last few years, advances in technology coupled with the continual focus on improving surgical outcomes have resulted in refinements in surgery that do not require a heart-lung machine. This surgery is called off-pump or beating heart surgery.

Surgery relying on a heart-lung machine
The heart-lung machine revolutionized cardiac surgery and made it possible for surgeons to stop the heart and repair diseased coronary arteries. This machine temporarily serves as the patient's heart and lungs so that the heart can be stopped, giving the surgeon a still and bloodless field in which to suture the bypass grafts around the diseased coronary arteries.

The process of putting patients on the heart-lung machine, however, can have negative effects. Circulating a patient's blood through the machine can trigger a systemic inflammatory response and lead to organ dysfunction, bleeding and neurological complications, including stroke. So, although conventional CABG has a perioperative mortality rate of 2 percent or less (mortality rate averages under 1 percent at YNHH), the overall complication rate—infection, bleeding, strokes, cognitive impairments—can be much higher.

Comparing off- and on-pump cardiac surgery
This British study gives us the benefit of looking at large numbers of at-risk patients undergoing cardiac surgery, so we are able to see if there are differences between off- and on-pump cardiac surgery with regard to the incidence of stroke. What's important to keep in mind is that the overall outcomes of cardiac surgery, whether they are done using the heart-lung machine or not, are excellent. The incidence of strokes is very small, even in elderly patients, who would be more likely to have compromised circulation than younger patients.

Cognitive changes may be associated with on-pump surgery
Although the reason for cognitive changes is not yet definitely known, many physicians believe the changes are related to the fact that emboli (tiny particles, most commonly atherosclerotic plaque) are dislodged into the bloodstream when the heart-lung bypass machine is used. (Studies that used transcranial Doppler ultrasound of the middle cerebral arteries to detect micro-emboli showed a 30-fold reduction in these emboli when off-pump surgery is performed.) As the emboli travel throughout the circulation, they may affect the brain, resulting in cognitive dysfunction or block the vessel, resulting in stroke. Older people who are more likely to have some calcification in the blood vessels going to the head are at higher risk for these phenomena.

Local data
The desire to avoid or minimize these complications led to off-pump coronary artery bypass (OPCAB) grafting in which we use a device to stabilize the heart and then proceed with surgery with the patient's heart still beating. My own data from several hundred surgeries are similar to those found in this study.

In 477 off-pump surgeries, I had two cases of stroke and four confusional episodes in which the patient awakes from surgery in an agitated and confused state. That compares to five strokes in 450 on-pump surgeries and 10 confusional episodes.

There are some additional benefits to OPCAB:

• Less chance of wound infection
• Less bleeding postoperatively
• Lower incidence of kidney complications
• Quicker recovery from anesthesia
• Quicker recuperation.

Who should consider off-pump surgery?
I currently perform a little more than 60 percent of my surgeries off pump. Patients who are at high risk for complications from cardiopulmonary bypass are particularly good candidates for OPCAB. These include individuals with chronic lung disease, vascular disease, previous strokes or mini-strokes and those in their 70s or older.

OPCAB is not for everyone, however. Those who have valve disease, enlarged ventricles or large amounts of fat and muscle around their coronary arteries are not good candidates for this surgery.

If you are contemplating cardiac surgery, talk with your cardiologist or surgeon about whether you are a candidate for off-pump surgery. As with any surgical technique, experience is important, so if you are considering off-pump surgery, be sure to consult with a surgeon who has performed a high volume of OPCABs.

Dr. Dewar is a cardiothoracic surgeon and a partner with Cardiothoracic Surgical Associates in New Haven. He is an attending physician at Yale-New Haven Hospital and Yale-New Haven Heart Center and an assistant clinical professor of cardiothoracic surgery at the Yale School of Medicine.