Session cochair Jeffrey S. Borer, M.D., the Gladys and Roland Harriman Professor of Cardiovascular Medicine, professor of radiology and of cardiothoracic surgery, and chief of the division of cardiovascular pathophysiology at Cornell University, New York, praised Dr. Elefteriades for providing “extraordinarily insightful data with enormous clinical implications.”
The Mechanics of Aortic Dissection
Dr. Elefteriades described the sequence of events that results in acute aortic dissection, based on the work that he and his colleagues have done.
First, a genetic predisposition to aneurysm formation leads over the course of many years to aortic dilation. When this reaches a critical point—the mean aortic diameter in the 90-patient series was 5.56 cm—an extreme physical or emotional trigger boosts systemic blood pressure to a level beyond the mechanical capacity of the thinned and weakened aorta.
“That's why the dissection occurs at a particular instant,” the surgeon said.
A colleague has developed an apparatus for noninvasive measurement of blood pressure from moment to moment. Applying it during a weight-lifting workout, Dr. Elefteriades found that his systolic pressure climbed from a baseline of 130 to 270 mm Hg while he bench pressed his own weight. Another physician's blood pressure jumped to 320 mm Hg.
“I never see blood pressures like that in the ICU taking care of ill people,” he observed.
Olympic-caliber weight lifters, he subsequently determined, raise their blood pressure as high as 380 mm Hg while lifting barbells. In mechanical studies, Dr. Elefteriades found that the tensile strength of an enlarged aortic wall—that is, its rupture point—is about 800 kilopascals. That's exceeded when blood pressure in an enlarged and weakened aorta exceeds about 200 mm Hg.