Stollery Children's Hospital, University of Alberta, Edmonton, Alberta, Canada.
Curr Opin Pediatr. 2011 Oct;23(5):512-7. doi: 10.1097/MOP.0b013e32834aa56a.
Despite improvements in surgical techniques, valvular regurgitation results in major morbidity in children with heart disease. Functional anatomy, mechanisms of valve closure and adaptation to changing hemodynamic stress in normal mitral and tricuspid valves are complex and only partially understood. As well, pathology of atrioventricular valve regurgitation is further complicated by congenital valve abnormalities involving leaflet tissue, supporting chordal apparatus and displaced papillary muscles. This review provides a current understanding of the mechanisms that result in atrioventricular valve failure.
Mitral valve leaflets have contractile elements, in addition to atrial muscle modulation of leaflet tension. When placed under mechanical tethering stress, the mitral valve adapts by leaflet expansion, which increases coaptation surface reserve and chordal thickening. Both pediatric and adult studies are increasingly reporting on the importance of subvalvar apparatus function in maintaining valve competency.
The maintenance of efficient valve function is accomplished by a complex series of events involving atrial and annular contraction, annular deformation, active leaflet tension, chordal transmission of papillary muscle contractions and ventricular contraction.
尽管手术技术有所改进，但心脏疾病患儿的瓣膜反流仍会导致严重的发病率。正常二尖瓣和三尖瓣的功能解剖、瓣膜关闭机制和适应不断变化的血流动力学压力的能力非常复杂，目前仅部分被了解。此外，房室瓣反流的病理学还因涉及瓣叶组织、支持腱索装置和移位乳头肌的先天性瓣膜异常而变得更加复杂。本篇综述提供了目前对导致房室瓣功能障碍的机制的理解。
除了心房肌肉对瓣叶张力的调节外，二尖瓣瓣叶还有收缩成分。当瓣叶受到机械束缚的压力时，通过瓣叶扩张来适应，这增加了对合面储备和腱索增厚。儿科和成人研究都越来越多地报告了瓣下装置功能在维持瓣膜功能中的重要性。
高效瓣膜功能的维持是通过一系列复杂的事件来实现的，包括心房和环的收缩、环的变形、主动瓣叶张力、乳头肌收缩的腱索传递和心室收缩。
