Department of Pediatric Cardiology, Cleveland Clinic Children's, and Cardiovascular Medicine Department, The Heart, Vascular, & Thoracic Institute, Cleveland Clinic Foundation, Cleveland, Ohio, USA.
Heart Institute, Cincinnati Children's Hospital Medical Center, Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA.
Clin Anat. 2023 Jul;36(5):836-846. doi: 10.1002/ca.24032. Epub 2023 Mar 16.
The ventricular components of the conduction axis remain vulnerable following transcatheter aortic valvar replacement. We aimed to describe features which may be used accurately by interventionalists to predict the precise location of the conduction axis, hoping better to avoid conduction disturbances. We scanned eight normal adult heart specimens by 3T magnetic resonance, using the images to simulate histological sections in order accurately to place the conduction axis back within the heart. We then used histology, tested in two pediatric hearts, to prepare sections, validated by the magnetic resonance images, to reveal the key relationships between the conduction axis and the aortic root. The axis was shown to have a close relationship to the nadir of the right coronary leaflet, in particular when the aortic root was rotated in counterclockwise fashion. The axis was more vulnerable in the setting of a narrow inferoseptal recess, when the inferior margin of the membranous septum was above the plane of the virtual basal ring, and when minimal myocardium was supporting the right coronary sinus. The features identified in our study are in keeping with the original description provided by Tawara, but at variance with more recent accounts. They suggest that the vulnerability of the axis during transcatheter valvar replacement can potentially be inferred on the basis of knowledge of the position of the aortic root within the ventricular base. If validated by clinical studies, our findings may better permit avoidance of new-onset left bundle branch block following transcatheter aortic valvar replacement.
经导管主动脉瓣置换术后，传导轴的心室部分仍然容易受损。我们旨在描述介入医生可以准确使用的特征，以预测传导轴的确切位置，希望更好地避免传导障碍。我们使用 3T 磁共振对 8 个正常成人心脏标本进行了扫描，使用图像模拟组织学切片，以便准确地将传导轴放回心脏内。然后，我们使用组织学，在 2 个儿科心脏中进行测试，准备切片，并通过磁共振图像进行验证，以揭示传导轴与主动脉根部之间的关键关系。结果表明，传导轴与右冠状动脉瓣叶的最低点密切相关，特别是当主动脉根部逆时针旋转时。当间隔下隐窝狭窄时，膜部间隔的下边缘高于虚拟基底部环的平面，并且当右冠状动脉窦仅由少量心肌支撑时，传导轴更容易受损。我们研究中确定的特征与 Tawara 最初的描述一致，但与最近的描述不同。它们表明，在基于对心室基底内主动脉根部位置的了解的基础上，有可能推断出轴的脆弱性。如果通过临床研究得到验证，我们的发现可能会更好地避免经导管主动脉瓣置换术后新发左束支传导阻滞。
