The functional limits of the aneurysmal aortic root. A unique pressure testing apparatus
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(2020) 15:259
RESEARCH ARTICLE
Open Access
The functional limits of the aneurysmal aortic root. A unique pressure testing apparatus Timothy Luke Surman1* , John Matthew Abrahams1, Dermot O’Rourke2, Karen Jane Reynolds2, James Edwards1, Michael George Worthington1 and John Beltrame3
Abstract Background: The 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. Methods: We 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. Results: In the aortic root, mean maximal pressure (mmHg) at tissue failure was 208 mmHg. 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 300 mmHg without tissue failure or dissection, and eventual apparatus failure. Conclusion: Our 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. Keywords: Ascending aorta aneurysms, Ascending aortic dissection, Aortic root, Thoracic aorta, Inflation testing
Background Ascending aortic dissection is the most common catastrophe of the aorta; it is two to three times more common than rupture of the abdominal aorta [1]. Mortality rate of untreated acute dissection involving the ascending aorta is * Correspondence: [email protected] 1 D’Arcy Sutherland Cardiothoracic Surgical Unit, Royal Adelaide Hospital, Adelaide, South Australia, Australia Full list of author information is available at the end of the article
about 1–2% per hour during the first 48 h [2] The first documented case was King George II in 1760 [2]. Constant exposure to high pulsatile pressure and shear stress leads to a weakening of the aortic wall in susceptible patients resulting in an intimal tear [3] Mo
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