Dr. Hernan Bazan, Assistant Professor of Surgery, Section of Vascular Surgery, at Louisiana State University Health Sciences Center New Orleans' School of Medicine, is the lead author of a research paper which may help physicians decide which patients with carotid artery occlusive disease should have carotid surgery or carotid stenting. The research sheds light on characteristics of the aortic arch that could help explain why octogenarians, patients over the age of 80 years, have a higher risk of embolization and stroke during carotid artery stenting (CAS), an artery expanding procedure promoting blood flow done to prevent stroke, and how early identification may allow planning of alternative techniques to reduce risk.
"We hypothesized that elderly patients have more heavily calcified arches than younger patients," noted Dr. Bazan. "It is possible that heavily calcified aortic arches could be a source of increased embolization during wire manipulation and catheter exchanges at some stage in carotid artery stenting. We also sought to define what the arches look like or what their morphology is and found that in patients over the age of 75 years, there was a dramatic increase in calcium content and more complex aortic arches."
The research team analyzed the calcium content and aortic arch type in a consecutive series of patients undergoing thoracic computed tomography (CT) scans to determine whether aortic arch calcium content is related to either age or arch type classification. (The aortic arch is the bend between the ascending and descending aorta sections from which the carotid arteries branch.)
Patients under 40 or those who had recently undergone thoracic aortic or cardiac valve surgery were excluded. The CT scans of 94 patients were analyzed. There was a positive correlation between age and aortic arch calcium content and the mean calcium score for patients increased by decade. There was significantly more arch calcium in patients 75 years or older. Because elderly patients may develop elongated and tortuous arches, the research team also examined whether arch type was associated with calcium content. Patients with type II aortic arches, a class of more 'complex anatomy,' had a higher calcium content compared with patients with type I aortic arches.
These findings suggest that increased aortic arch calcium content and arch elongation may be used as markers of increased potential for embolization during endovascular manipulation of the aortic arch. Multiple reports have documented an increased periprocedural stroke risk with CAS in octogenarians. An increased stroke risk in elderly patients is likely to prevent widespread applicability of CAS in these patients.
According to the American Heart Association, on average, every 45 seconds, someone in the United States has a stroke--500,000 a first stroke and 200,000 recurrent attacks each year. Eighty-seven percent of strokes are ischemic--caused by blocked blood flow. The prevalence of transient ischemic attacks (mini strokes that last less than 24 hours) increases with age. Stroke is the third leading cause of death in the US accounting for 1 in every 16 deaths in 2004.
"Early identification of these arches at higher risk for embolic complications may allow planning of alternative techniques associated with less manipulation of the arch, such as the use of soft-tip guide catheters rather than stiff sheaths or use of the transcervical approach," said Dr. Bazan. "These maneuvers could potentially decrease the periprocedural risk of stroke. I think more and more physicians will regard age as a patient-specific factor that is a marker for aortic arch calcification and arch complexity. Preprocedural determination of aortic arch morphology and calcification may help to determine which elderly patients are at increased risk for stroke during CAS. Using this information, it may be more beneficial to offer surgery to treat the carotid occlusive disease and, therefore, minimize the risk of stroke during the procedure."
Increased aortic calcification in patients older than 75 years: Implications for carotid artery stenting in elderly patients is published in the November 2007 issue of the Journal of Vascular Surgery.
Materials provided by Louisiana State University Health Science Center. Note: Content may be edited for style and length.
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