Perioperative protection for right heart in patients with apical displacement of tricuspid valve leaflets / 中国胸心血管外科临床杂志

@#The apical displacement of tricuspid valve leaflets complicated with significantly enlarged, thin and fibrotic wall of the right ventricle is prone to dysfunction of right heart. Therefore, the myocardial protection for the right ventricle is important. Based on the pathological changes, an algorithm of perioperative myocardial protection strategy is summarized. Firstly, we should clearly know that the right ventricular myocardium with severe lesions is much different from the unimpaired myocardium, because it is now on the margin of failure; secondly, right heart protection should be regarded as a systematic project, which runs through preoperative, intraoperative and postoperative periods, and requires close collaboration among surgeons, perfusionists, anesthesiologists and ICU physicians. In this article, we try to introduce the systematic project of the right heart protection, in order to improve the outcome of this population.

Numerical modeling and biomechanical analysis of the human mitral valve / 医用生物力学

Objective To establish a numerical model of human mitral valve and simulate its closing process, so as to analyze stress distributions on the valve apparatuses, study the interaction between leaflets of mitral valve and chordae tendineae, and explore the relationship between the force of chordae tendineae and their thickness. Methods A geometric model of human mitral valve was constructed. On the basis of the geometric model, the finite element model was established by defining the element type, material attributes, contacts, loads and constraints. Parameters such as stress, velocity and displacement were calculated after solving the model. Results The stress distribution on the valve was non-uniform. The clefts between the scallops in the posterior leaflet were always under the highest load. When no chordae tendineae were attached, the leaflets turned over to the side of the atrium. When chordea tendineae were attached, the anterior and posterior leaflet could close up successfully. Different chordae tendineae applied different forces to the valve. The strut chorea tendineae attached to the anterior leaflet applied highest force among all the chordea tendineae. The correlation coefficient between the thickness of chordae tendineae and their force was 0.954. Conclusions The two zones with higher stresses, namely the center of the leaflet and the clefts between the three scallops in the posterior leaflet, are also the positions of mitral valve cleft in clinic. Chordea tendineae can apply the pulling force on the leaflets while the mitral valve is under load, thus the leaflets won’t turn over to the side of atrium and the valve can close up in time. Chordea tendineae with thicker anatomic structure always apply a higher force on the leaflets.