Two commonly used approaches to protect the brain during surgery to repair an ascending aortic aneurysm are equally effective, according to a review by the University of Miami Miller School of Medicine researchers published October 6 in the Journal of Cardiac Surgery.
An ascending aortic aneurysm is an abnormal bulge or weakening of part of the aorta, which is the main blood vessel that carries oxygenated blood away from the heart to the rest of the body. Surgical repair of the ascending aorta often involves replacing a failing aortic valve.
"During surgery, we have to stop the circulation. But when you stop the circulation, you must keep the brain cold and have a blood source to the brain. That can be done in two ways, with antegrade or retrograde cerebral perfusion," said author Joseph Lamelas, M.D., chief of cardiothoracic surgery and professor of surgery in the Miller School of Medicine.
Pumping blood backwards through the superior vena cava (veins) into the brain is retrograde cerebral perfusion. Pumping blood directly into the carotid arteries is antegrade cerebral perfusion. In the retrograde approach, surgeons temporarily reroute the flow of cold blood into the brain through the superior vena cava, which is opposite to its normal flow.
Antegrade cerebral perfusion involves directing blood flow into each of the arteries that go into the brain and the arms and pumping cold blood in the normal direction of blood flow.
There has long been controversy about whether antegrade cerebral perfusion offers better cerebral protection than retrograde cerebral perfusion. To determine if one is better than the other, we conducted a review of the literature and found both are equally excellent options in the hands of experienced cardiothoracic surgeons."
Joseph Lamelas, MD, Study Author and Chief of Cardiothoracic Surgery, Professor of Surgery, Miller School of Medicine, University of Miami Health System
This is reassuring given that the antegrade approach is not always an option.
Surgeons who perform traditional surgical replacement of the ascending aorta, which involves dividing the sternum to gain access to the heart, can use either the antegrade or retrograde approach. Dr. Lamelas has pioneered and published on minimally invasive replacement of the ascending aorta.
It does not involve dividing the patient's sternum, rather, Dr. Lamelas performs the procedure through a 5cm incision on the right side of the chest.
"When I perform this minimally invasive operation, the only way for me to protect the brain is by pumping it through the veins, which is retrograde," he said. "Our article demonstrates that the retrograde approach offers equal cerebral protection."
Dr. Lamelas, who in his 31 years as a cardiothoracic surgeon has performed 17,000 heart surgeries, said he is not surprised by the results.
"I have been using the retrograde technique for the last 30 years and have had tremendous success using retrograde cerebral perfusion in a few thousand patients, including those having minimally invasive replacement of the ascending aorta," he said. "What is most important in these complex operations is the surgeons' experience."
Patients facing surgery to repair an aortic aneurysm need to be educated about their options, including whether they are candidates for a less invasive approach to open-heart surgery, he said.
"There are so many patients today who are candidates for the minimally invasive approach, which has been shown to reduce time in the hospital and intensive care unit, reduce transfusion risk and result in faster recoveries," Dr. Lamelas said.
"Patients should pick a surgeon with experience, because performing the operation through a small incision doesn't make one a better surgeon. You have to be comfortable doing any operation with a traditional approach, so when you embark on a lesser invasive approach you are proficient and have the experience to perform it safely and achieve the best results possible."
Alnajar, A., et al. (2020) Review of cerebral perfusion strategies for aortic surgery with application for minimally invasive approaches. Journal of Cardiac Surgery. doi.org/10.1111/jocs.15061.