ATLANTA --By performing coronary bypass surgery on a beating heart, instead of on a still heart, Duke University Medical Center physicians have shown that they can reduce intensive care unit stays and costs. This is partly due to decreasing the amount of time necessary for a patient to need a ventilator.
This new approach emerged on the surgical scene about three years ago and appears to offer the same results as conventional bypass surgery, with the important difference that the patient is not supported by a heart-lung machine during surgery. While a heart-lung machine allows surgeons to operate on a totally still heart, it is thought to be a source of potential negative side effects such as stroke and cognitive decline after surgery.
The study, one of the few to examine the economic impact of the new technique with respect to ICU care, involved the first 32 patients to receive off-pump coronary artery bypass (OPCAB) surgery at Duke. Although the study was small, researchers said they believe the results show that OPCAB has great potential in getting patients back to their normal activities sooner and at less cost.
"We can improve patient comfort after surgery by not spending much time on a ventilator, decrease ICU stays and costs, and at the same time provide the same quality of surgery without the potential negative side effects of being on the heart-lung machine," said Duke anesthesiologist Dr. Katherine Grichnik. "Larger studies are needed as surgeons gain a larger experience with beating-heart surgery, but we're very excited about the prospects."
The results of the Duke study were prepared for presentation Friday by Grichnik at the 7th annual meeting of the International Society for Minimally Invasive Cardiac Surgery. The research was supported by the Duke departments of anesthesiology and surgery.
For their study, the researchers compared the treatment and recovery of the 32 OPCAB patients with 30 other "traditional" bypass patients (who used the heart-lung machine) treated at Duke who possessed the same characteristics, such as number of vessels bypassed, gender, age, co-existing diseases and pre-surgical heart function.
The researchers found that: OPCAB patients had their breathing tubes removed much sooner --8 hours compared to 65 hours -- after surgery than conventionally treated patients. OPCAB patients remained in the ICU for much less time --24.4 hours compared to 111.4 hours -- than those treated with conventional surgery. The average costs for respiratory care services for OPCAB patients were $936, compared to $1,635 for traditionally treated. Overall, ICU costs for OPCAB patients were $2,716, compared to $5,009 for traditionally treated patients.
In a traditional bypass procedure, surgeons stop the heart in order to have a non-moving surface on which to perform their delicate suturing. Gaining this stillness, however, involves re-routing a patient's blood through the heart-lung machine. While this machine has revolutionized heart surgery, it does come with risks, especially the risk of stroke.
"My surgical colleagues have refined their surgical skills during the past 15 years with excellent cardiac outcomes, but one thing has remained constant --between 1 to 5 percent of patients undergoing heart surgery may suffer an adverse neurological outcome," Grichnik said. "In part, this is because the process of placing the tubes to connect patients to the heart-lung machine can dislodge plaques along arteries that can subsequently travel to the brain and cause a stroke."
What has made beating heart surgery possible, the researchers say, has been the recent development of specialized instruments that can stabilize small areas of the heart to allow a cardiac surgeon to safely place a bypass graft. Patients spend less time on a breathing tube and in the ICU for many reasons: 1) the surgery is, in general, shorter and therefore requires less narcotic use; 2) because the patients don't require high doses of anticoagulants for a heart-lung machine, spinal narcotics may be used to increase comfort without drowsiness; 3) patients may suffer less bleeding intraoperatively and postoperatively; and 4) patients remain warm for the OPCAB surgery as compared to conventional bypass done with patients being cooled.
"In a traditional bypass, we give patients anesthetics with the goal of having people awaken a few hours after surgery," Grichnik explained. "With OPCAB, our goal is for them to wake up right after surgery. In many cases, we can remove the breathing tube in the operating room.
"With shorter intubation times come many good things for patients --reduced risks of pneumonia, less vocal cord irritation, less inflammation of the airways, less discomfort and shorter ICU stays," Grichnik said.
Unlike traditional bypass operations, patients undergoing OPCAB surgery do not need systemic body cooling, which is used to reduce the metabolic needs of the stopped heart. Recent Duke studies have shown that the rewarming process after surgery can cause cognitive deficits in some patients.
While OPCAB appears to offer many advantages, it also poses special challenges for both surgeons and anesthesiologist alike, the investigators say. For example, as the beating heart is manipulated by the surgeon, anesthesiologists must be able to respond to the sudden blood pressure changes that can result. Also, as the portion of heart to receive a bypass graft is stabilized, it receives less oxygenated blood, which means that surgeons have about 20 minutes to finish the suturing in that particular area.
"As more and more heart cases are being handled this way, surgeons and anesthesiologists alike have adjusted well to the new techniques," Grichnik said. "As time goes on, we believe that more studies will demonstrate further benefits of OPCAB."
The OPCAB procedures were performed by Duke surgeon Dr. Kevin Landolfo. Others on the Duke research team were Dr. Robert Panten, Dr. Mark Newman, Dr. Maribel Gamoso and Dr. Peter Kasikis.