Department of Anatomy, Post Graduate Institute of Medical Education and Research, Chandigarh, 160012.
Department of Anatomy, Post Graduate Institute of Medical Education and Research, Chandigarh, 160012.
Cardiovasc Pathol. 2017 Sep-Oct;30:38-44. doi: 10.1016/j.carpath.2017.06.005. Epub 2017 Jun 30.
Atrioventricular (AV) nodal injury which results in cardiac conduction disorders is one of the potential complications of heart valve surgeries and radiofrequency catheter ablations. Understanding the topography of the AV conduction system in relation to the tricuspid and mitral valves will help in reducing these complications.
A tissue block of 3cmx4cm, which contain the AV node, bundle of His and the AV nodal extensions, was excised at the AV septal junction in 20 apparently normal human hearts. The block was divided into three equal segments through vertical incisions perpendicular to the insertion of the septal leaflet of the tricuspid valve. Each segment was processed and stained with H&E and Gomori to study the different parts of the AV conduction system.
The lower pole of the AV node was located vertically above the tricuspid septal leaflet (TSL) in 100% (20/20) of cases and at the level of the muscular interventricular septum in 65% (13/20) of cases. The upper pole of the compact AV node was located at the level of the mitral valve leaflet (MVL) in 50% (10/20) of cases. The penetrating bundle of His was seen at the level of the TSL, while the branching bundle of His was situated 1.9±1.5 mm inferior to the TSL. The right and left posterior extensions of the AV node spanned from the MVL to 2.9±1.3 mm above the TSL.
A rectangular area (2.5 mm × 12 mm) in the Koch's triangle was devoid of AV nodal tissue and could be labeled as a safe area with no risk of conduction defects during valve surgeries. Information on the separation of AV nodal extensions from the TSL, MVL and muscular interventricular septum may play a crucial role in guiding and improving the safety of radiofrequency ablations.
房室（AV）结损伤导致心脏传导障碍是心脏瓣膜手术和射频导管消融术的潜在并发症之一。了解 AV 传导系统与三尖瓣和二尖瓣的关系有助于减少这些并发症。
在 20 个明显正常的人心房中，在房室间隔交界处切除一块 3cmx4cm 的组织块，其中包含 AV 结、希氏束和 AV 结延伸。通过垂直于三尖瓣隔瓣插入处的垂直切口将该组织块分为三个相等的节段。对每个节段进行处理和 H&E、Gomori 染色，以研究 AV 传导系统的不同部位。
AV 结的下极在 100%（20/20）的病例中垂直位于三尖瓣隔瓣（TSL）上方，在 65%（13/20）的病例中位于室间隔心肌水平。致密 AV 结的上极在 50%（10/20）的病例中位于二尖瓣瓣叶（MVL）水平。穿透性希氏束位于 TSL 水平，而分支希氏束位于 TSL 下方 1.9±1.5mm。AV 结的右后和左后延伸从 MVL 延伸至 TSL 上方 2.9±1.3mm。
在 Koch 三角内有一个 2.5mm×12mm 的矩形区域没有 AV 结组织，可以标记为安全区域，在瓣膜手术中不会导致传导缺陷。关于 AV 结延伸与 TSL、MVL 和室间隔心肌的分离信息可能在指导和提高射频消融安全性方面发挥关键作用。
