Aortic nightmares: can we sleep better?

See related article on page 1451. O ne of the recurring nightmares facing surgeons who operate on the thoracic aorta involves incising the aorta and visualizing severe degenerative atherosclerosis with toothpaste-like material in the wall of the aorta and the interior of the aorta lined with ulcerations containing platelet, fibrin strands, and, in some cases, actual blood clots. If a clamp is applied to this aorta, it is not difficult to imagine this material breaking away and embolizing to vital organs, causing severe complications. As the authors of “Embolic material generated by multiple aortic crossclamping: A perfusion model with human cadaveric aorta” point out, repeated clamping of atherosclerotic aortas releases not only calcified atherosclerotic debris, but smaller emboli consistent with cellular debris as well. On the basis of their data, it is hard to believe that any patient with aortic atherosclerosis, who undergoes surgery involving aortic clamping, does not end up with some permanent, severe organ damage related to intraoperative embolization. Fortunately, a quick review of the cardiac surgery literature would suggest that the incidence of permanent stroke, renal failure, and other severe organ damage and death are quite low in clinical cardiac surgery today, although it has been pointed out by a number of authors that risk factors for organ damage during cardiopulmonary bypass are greatly amplified by the presence of severe atherosclerosis of the thoracic aorta and its branches. What then can be done to minimize the risk of potential embolization and what is the future for cardiopulmonary bypass in patients with severe aortic atherosclerosis? As we have shown from data collected in patients from our own institution, and others have likewise pointed out, patients with palpable aortic atherosclerosis have a higher incidence of ultrasound-detected emboli during cardiac surgery. There is no question that surgeons strive to avoid placing crossclamps and perform other aortic manipulations across areas of palpable atherosclerosis. As Davila-Roman and his group have pointed out, however, all aortic atherosclerosis is not palpable. They have popularized a technique of epiaortic ultrasound scanning to map the aorta in areas of potential manipulation to determine whether atherosclerotic material is present. These techniques have become more widespread throughout the cardiac surgical community and, when combined with transesophageal echocardiography, give the surgeon a concrete idea of the presence of atherosclerosis in areas where clamps or incisions may be applied. Thus, it is possible to manipulate the aorta in areas where atherosclerosis is not present in the vast majority of cases. It appears from the data given to us by Boivie and colleagues that the one patient without calcified atherosclerosis had many fewer potential emboli, even on repeated clamping. Thus, we must focus our attention on patients with detectable, severe atherosclerosis. What is the surgeon to do if the aorta is extensively diseased? Fortunately, there are many solutions for patients, particularly undergoing CABG operation. A popular option to avoid cannulation and pump flow–induced aortic trauma is to perform off-pump operations. Even in these operations, aortic manipulation, especially with partial occlusion clamps, must be avoided as emphasized by Calafiore and associates. Grafts may be based off the internal mammary artery and the only chance for aortic manipulation is when the heart is distracted to provide access to vessels on the obtuse margin and posterior and inferior walls of the heart. If the surgeon chooses to use cardiopulmonary bypass, a no-touch technique may be utilized by allowing the heart to remain beating or fibrillating and the same intraoperative stabilization From the Wake Forest University Health Sciences, Winston-Salem, NC.