Department of Radiology and Nuclear Medicine, University Hospital Schleswig-Holstein, Lübeck, Germany.
Department of Radiology and Nuclear Medicine, University Hospital Schleswig-Holstein, Lübeck, Germany.
J Thorac Cardiovasc Surg. 2020 Mar;159(3):798-810.e1. doi: 10.1016/j.jtcvs.2019.02.127. Epub 2019 Apr 5.
The aim of this study was to compare aortic flow patterns in patients after David valve-sparing aortic root replacement with physiologically shaped sinus prostheses or conventional tube grafts in healthy volunteers.
Twelve patients with sinus prostheses (55 ± 15 years), 6 patients with tube grafts (58 ± 12 years), 12 age-matched, healthy volunteers (55 ± 6 years), and 6 young, healthy volunteers (25 ± 3 years) were examined with time-resolved 3-dimensional magnetic resonance phase contrast imaging (4D Flow MRI). Primary and secondary helical, as well as vortical flow patterns, were evaluated. Aortic arch anatomy as a flow influencing factor was determined.
Compared with volunteers, both sinus prostheses and tube grafts developed more than 4 times as many secondary flow patterns in the ascending aorta (sinus prostheses n = 1.6 ± 0.8; tube grafts n = 1.3 ± 0.6; age-matched, healthy volunteers n = 0.3 ± 0.5; young, healthy volunteers n = 0; P ≤ .012) associated with a kinking of the prosthesis itself or at its distal anastomosis. As opposed to round aortic arches in volunteers (n = 16/18), cubic or gothic-shaped arches predominated in patients (n = 16/18, P < .001). In all but 3 volunteers, 2 counter-rotating helices were confirmed in the ascending aorta and were defined as a primary flow pattern. This primary flow pattern did not develop in patients who underwent valve-sparing aortic root replacement.
In patients after valve-sparing aortic root replacement, there was an increased number of secondary flow patterns in the ascending aorta. This seems to be related to surgically altered aortic geometry with kinking. Because flow alterations are known to affect wall shear stress, there seems to be an increased risk for vessel wall remodeling. Compared with previous 4D Flow MRI studies, primary flow patterns in the ascending aorta in healthy subjects were confirmed to be more complex. This underlines the importance of thorough examination of 4D Flow MRI data.
本研究旨在比较窦部保留型主动脉根部替换术后使用生理成型窦部假体与传统管状移植物的患者与健康志愿者之间的主动脉血流模式。
12 名使用窦部假体的患者（55±15 岁）、6 名使用管状移植物的患者（58±12 岁）、12 名年龄匹配的健康志愿者（55±6 岁）和 6 名年轻健康志愿者（25±3 岁）接受时间分辨 3 维磁共振相位对比成像（4D Flow MRI）检查。评估主要和次要螺旋以及涡流血流模式。确定主动脉弓解剖结构作为影响血流的因素。
与志愿者相比，窦部假体和管状移植物在升主动脉中均形成超过 4 倍的次级血流模式（窦部假体 n=1.6±0.8；管状移植物 n=1.3±0.6；年龄匹配的健康志愿者 n=0.3±0.5；年轻健康志愿者 n=0；P≤0.012），这与假体本身或其远端吻合处的扭曲有关。与志愿者的圆形主动脉弓（n=16/18）相反，患者的主动脉弓呈立方或哥特式形状为主（n=16/18，P<0.001）。除了 3 名志愿者外，在升主动脉中均证实存在 2 个反向旋转的螺旋，将其定义为主要血流模式。这种主要血流模式在接受窦部保留型主动脉根部替换术的患者中并未形成。
在窦部保留型主动脉根部替换术后的患者中，升主动脉中的次级血流模式数量增加。这似乎与手术改变的主动脉几何形状导致的扭曲有关。由于已知血流改变会影响壁切应力，因此似乎存在血管壁重塑的风险增加。与之前的 4D Flow MRI 研究相比，健康受试者升主动脉中的主要血流模式被证实更为复杂。这强调了对 4D Flow MRI 数据进行彻底检查的重要性。
