Markl Michael, Draney Mary T, Miller D Craig, Levin Jonathan M, Williamson Eric E, Pelc Norbert J, Liang David H, Herfkens Robert J
Department of Radiology, Stanford University, CA 94304, USA.
J Thorac Cardiovasc Surg. 2005 Aug;130(2):456-63. doi: 10.1016/j.jtcvs.2004.08.056.
To provide more complete characterization of ascending aortic blood flow, including vortex formation behind the valve cusps, in healthy subjects and patients after valve-sparing aortic root replacement (David reimplantation).
Time-resolved 3-dimensional magnetic resonance imaging velocity mapping was performed to analyze pulsatile blood flow by using encoded 3-directional vector fields in the thoracic aortas of 10 volunteers and 12 patients after David reimplantation using a cylindrical tube graft (T. David I) and two versions of neosinus recreation (T. David-V and T. David-V-S mod ). Aortic flow was evaluated by using 3-dimensional time-resolved particle traces and velocity vector fields reformatted onto 2-dimensional planes. Semiquantitative data were derived by using a blinded grading system (0-3: 0, none; 1, minimal; 2, medium; 3, prominent) to analyze the systolic vortex formation behind the cusps, as well as retrograde and helical flow in the ascending aorta.
Systolic vortices were seen in both coronary sinuses of all volunteers (greater in the left sinus [2.5 +/- 0.5] than the right [1.8 +/- 0.8]) but in only 4 of 10 noncoronary sinuses (0.7 +/- 0.9). Comparable coronary vortices were detected in all operated patients. Vorticity was minimal in the noncoronary cusp in T. David-I repairs (0.7 +/- 0.7) but was prominent in T. David-V noncoronary graft pseudosinuses (1.5 +/- 0.6; P = .035). Retrograde flow (P = .001) and helicity (P = .028) were found in all patients but were not distinguishable from normal values in the T. David-V-S mod patients.
Coronary cusp vorticity was preserved after David reimplantation, regardless of neosinus creation. Increased retrograde flow and helicity were more prominent in T. David-V patients. These novel magnetic resonance imaging methods can assess the clinical implications of altered aortic flow dynamics in patients undergoing various types of valve-sparing aortic root replacement.
更全面地描述健康受试者以及保留瓣膜主动脉根部置换术（David 再植入术）后患者升主动脉内的血流情况，包括瓣膜尖后方的涡流形成。
对 10 名志愿者和 12 名接受 David 再植入术的患者（使用圆柱形人工血管移植物（T. David I）以及两种版本的新窦重建术（T. David-V 和 T. David-V-S mod））的胸主动脉进行时间分辨三维磁共振成像速度映射，通过编码的三维矢量场分析搏动血流。使用三维时间分辨粒子轨迹和重新格式化为二维平面的速度矢量场评估主动脉血流。采用盲法分级系统（0 - 3 级：0 级，无；1 级，轻微；2 级，中等；3 级，显著）得出半定量数据，以分析瓣膜尖后方的收缩期涡流形成以及升主动脉内的逆行血流和螺旋血流。
所有志愿者的两个冠状窦均可见收缩期涡流（左窦[2.5±0.5]比右窦[1.8±0.8]更明显），但 10 个无冠状窦中只有 4 个可见（0.7±0.9）。在所有接受手术的患者中均检测到类似的冠状窦涡流。在 T. David-I 修复术中，无冠状瓣的涡度最小（0.7±0.7），但在 T. David-V 无冠状移植物假窦中涡度显著（1.5±0.6；P = 0.035）。所有患者均发现有逆行血流（P = 0.001）和螺旋度（P = 0.028），但在 T. David-V-S mod 患者中与正常值无差异。
无论新窦的创建情况如何，David 再植入术后冠状瓣涡度得以保留。T. David-V 患者的逆行血流增加和螺旋度增加更为明显。这些新的磁共振成像方法可评估接受各种类型保留瓣膜主动脉根部置换术患者主动脉血流动力学改变的临床意义。
