D'Arcy Sutherland Cardiothoracic Surgical Unit, Royal Adelaide Hospital, Adelaide, South Australia, Australia.
Medical Device Research Institute, College of Science & Engineering, Flinders University, Adelaide, South Australia.
J Cardiothorac Surg. 2020 Sep 17;15(1):259. doi: 10.1186/s13019-020-01288-8.
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.
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.
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.
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.
主动脉根部具有独特的胚胎发育过程，是一个高度复杂的结构。在报告胸主动脉生物力学特性的研究中，主动脉根部和升主动脉区域之间没有区别。我们的目的是确定在存在主动脉瘤的情况下，主动脉根部发生夹层或组织失效的最大压力与升主动脉相比。这可能有助于指导正常和易感人群的主动脉根部瘤术前监测、诊断和手术干预决策。
我们开发了一个简单的主动脉根部和升主动脉压力测试单元串联。从当地屠宰场获得了 10 个新鲜猪心（n = 5 个主动脉根部和 n = 5 个升主动脉用于比较）。使用充满盐水的针和注射器，在主动脉根部的内膜和中膜层之间创建人工充满液体的动脉瘤。然后，用生理盐水逐渐填充主动脉腔。在组织完整性丧失、明显组织夹层或动脉瘤破裂时进行压力测量，并对组织结构进行目视检查。
在主动脉根部，组织失效时的平均最大压力（mmHg）为 208mmHg。宏观检查显示，2/5 个标本的冠状动脉口周围有管腔撕裂，所有标本的主动脉根部夹层均呈环形扩展。在所有升主动脉标本中，最大主动脉压力超过 300mmHg 而没有组织失效或夹层扩展，最终仪器失效。
我们的结果表明，在较低的主动脉压力下，动脉瘤性主动脉根部组织更有可能破裂和夹层扩展。通过进一步分析，这可能有助于临床和手术管理。
