Key result
In a porcine model, simulated aneurysms in the aortic root ruptured at a mean maximal pressure of 208 mmHg, whereas the ascending aorta withstood pressures exceeding 300 mmHg without tissue failure.
Why the study?
Studies reporting on thoracic aorta biomechanical characteristics lack distinction between the aortic root and ascending aorta, prompting investigation into maximal pressures causing dissection or failure in aneurysmal roots versus ascending aortas.
Does the aneurysmal aortic root fail at lower pressures compared to the ascending aorta?
Does the aneurysmal aortic root fail at lower pressures compared to the ascending aorta?
Absolute Event Rate: 208% vs 300%
Aneurysmal aortic root tissues are at greater risk of rupture and dissection propagation at lower aortic pressures compared to the ascending aorta in a porcine model.
Aneurysmal aortic root may fail at lower pressures than ascending aorta; animal data leaves open human translation for rupture risk.
BackgroundThe aortic root has unique embryological development and is a highly sophisticated and complex structure. In studies that report on the biomechanical characteristics of the thoracic aorta, distinction between the aortic root and ascending aorta regions is nonexistent. Our objective is to determine the maximal pressures at which dissection occurs or tissue failure occurs in the aortic root compared to that of the ascending aorta in the presence of aortic aneurysms. This may help guide preoperative monitoring, diagnosis and the decision for operative intervention for aortic root aneurysms in the normal and susceptible populations.MethodsWe developed a simple aortic root and ascending aorta pressure testing unit in series. Ten fresh porcine hearts were obtained from the local abattoir (n=5 aortic root and n=5 ascending aorta for comparison). Using a saline filled needle and syringe, artificial fluid-filled aneurysms were created between the intima and medial layers of the aortic root. The aorta lumen was then progressively filled with saline solution. Pressure measurement was taken at time of loss of tissue integrity, obvious tissue dissection or aneurysm rupture, and the tissue structure was then visually examined.ResultsIn the aortic root, mean maximal pressure (mmHg) at tissue failure was 208mmHg. Macroscopic examination revealed luminal tears around the coronary ostia in 2/5 specimens, and in all specimens, there was propagation of the dissection in the aortic root in a circumferential direction. In all ascending aorta specimens, the maximal aortic pressures exceeded 300mmHg without tissue failure or dissection, and eventual apparatus failure.ConclusionOur results indicate that the aneurysmal aortic root tissues are at greater risk of rupture and dissection propagation at lower aortic pressure. With further analysis, this could guide clinical and surgical management.
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Surman et al. (2020) studied Aortic root and ascending aorta aneurysms (n=10). Simulated aneurysm pressure testing in the aortic root vs. Simulated aneurysm pressure testing in the ascending aorta was evaluated on Maximal pressure at tissue failure (mmHg). In a porcine model, simulated aneurysms in the aortic root ruptured at a mean maximal pressure of 208 mmHg, whereas the ascending aorta withstood pressures exceeding 300 mmHg without tissue failure.
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