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New configuration may avoid or delay re-CABGs
A new surgical technique for coronary artery bypass grafts has been shown to be safe, effective, and an economic improvement on surgical methods currently used for such operations. A study describing T-graft configuration was presented at the annual meeting of the Chicago-based Southern Thoracic Surgical Association in St. Louis earlier this year and will be published in a few months in the Annals of Thoracic Surgery. Investigators found that their technique results in longer-lasting bypasses with reduced chances for postoperative infections.
Researchers examined 650 patients who had undergone bypasses using T-graft configuration. They tracked operative survival, wound infection, and incidences of such conditions as stroke and found the operation to be safe and "a better alternative to current techniques used for bypasses," stated senior study author Hendrick B. Barner, MD, professor of cardiothoracic surgery at Washington University School of Medicine in St. Louis.
The mortality rate for patients in the study was 0.2% — one person out of 650 died within 30 days of the operation. "That’s an incredibly low rate," said Barner. "For low-risk patients, the rate for the standard procedures ranges from about 1% to 3%."
The T-graft configuration technique uses arteries from both the arm and chest to form a T-shaped conduit around the diseased portions of the heart. The study’s authors say the method, while complicated to master, offers surgeons a longer, wider conduit to work with as they revascularize the heart compared with using both internal thoracic arteries.
Traditional bypasses that use a leg vein as the conduit work well, but for a limited time, commented Barner, because the vein doesn’t "like" being part of the arterial system. What’s more, he said, veins used in bypass operations harden — about half close within 10 years, leaving patients back where they started.
Within 15 years of a bypass operation, some 75% of all veins develop atherosclerotic plaque, and patients "end up needing another bypass 10 years after the first one," he said. Over the last 20 years, surgeons have been substituting internal thoracic arteries for the leg veins because arteries outpace veins and remain disease-free at least twice as long.
The Washington University study examined the effectiveness of using one artery from the chest, the left internal thoracic artery, and one from the forearm, the radial artery. The primary benefit, stated Barner, is that the radial artery is longer than the right internal thoracic artery, offering surgeons more flexibility when fashioning the alternate conduit. Using the radial artery also lowers the risk of chest wound problems. When surgeons use both internal thoracic mammary arteries, they run the risk of sternal infections because that artery provides blood to the sternum. Breastbone infection was experienced by only four patients, or 0.6% of the study group.
What’s unique about Barner’s technique, though, is the configuration, which uses fewer arteries without reducing blood flow. The body hosts seven potential arterial conduits, two in the chest, two in the arm, one in the abdomen, and two in the lower abdominal wall, though the latter may be quite short and are of limited usefulness. With the T-graft technique, only two conduits are utilized instead of three, four, or five.
"If you use four arterial conduits in one operation, there’s only three left," said Barner, "and that could be a problem if you needed another operation at a future date."
Some surgeons were concerned that the T-graft may not provide enough blood flow to the heart muscle. Not so, said the investigator. Only 2%, or 14 patients, experienced temporary low-output syndrome, meaning that the heart still functioned below expected levels despite the surgery. Compared with 2% to 5% incidence of low cardiac output after coronary grafting, Barner said, "that number was gratifyingly low."