A NUMERICAL MODEL OF LEFT VENTRICLE AND AORTIC VALVE FUNCTION OF ITS AFTERLOAD(Ⅰ)

Due to the study of the function of heart and aoritic valve, we set up a physicalmodel of left ventricle, aortic valve and afterload and derive theoretical equation of each part from the model. Then we calculate the hasic equations within phystology and impair parameters. Bwsed on this, we will discus fully in the next paper the effectofleyt ventricular afterloadon valve opining, ejection and valve Jumction .etc

Isolated Tricuspid Valve Repair and Right Atrial Plication Performed Using a Beating-Heart Technique for Atrial Functional Tricuspid Valve Regurgitation

Background: Isolated tricuspid valve disease remains a controversial indication for surgical intervention. Many patients referred for surgery already have a poor clinical condition and an advanced New York Heart Association functional class. There is no consensus on the optimal surgical technique for this condition, including on whether to perform the procedure on a beating or an arrested heart and whether to perform valve repair or replacement. Methods: We analyzed four case series between 2015 and 2022 in which patients with secondary tricuspid regurgitation (TR) underwent valve repair on a beating heart and right atrial plication for a dilated right atrium. The TRI-SCORE was calculated for each patient. Results: All patients experienced a favorable postoperative course with significant improvements in heart failure symptoms. TR was markedly reduced;however, in one patient with concomitant mitral regurgitation (MR) and a high TRI-SCORE, MR worsened postoperatively. This patient later died from unknown causes due to multiple comorbidities in the late phase. Conclusions: Tricuspid valve repair on a beating heart was effective for improving the cardiac function, and the TRI-SCORE proved useful as a preoperative risk assessment tool. The underlying mechanism by which TR exacerbates MR requires further investigation.

Partial aortic root remodeling for root reconstruction in patients with acute type A dissection

In the present study, we reported our experience with partial aortic root remodeling for root reconstruction in patients with acute type A dissection, which involves in non-coronary sinus and/or the right coronary sinus with just one trimmed Dacron graft. Between February 2001 and May 2010, we performed partial aortic root remodeling in 40 patients, who underwent emergency surgical intervention. The dissected sinuses were excised leaving a 3-5 mm rim of the aortic wall from the attached aortic valve cusps. A short piece （4-5 cm） of collagen coated woven polyester vascular prosthesis was trimmed with one or two ＂tongues＂ to reconstruct the non-coronary sinus and/ or the right coronary sinus, but without using separated patches. Additional procedures were including hemi-arch replacement in 11 patients, and total arch replacement plus stent-elephant trunk in 20 patients. The mean follow-up time was 36.4~3.6 months. In-hospital mortality was only 5.0% （2/40）; furthermore, 3 （8.6%） patients underwent re-operation of the aortic valve and 2 （5.7%） patients died during follow-up. At the end of follow-up, trivial or no aortic regurgitation was found in 33 patients, but mild aortic regurgitation was found in 2 patients. Our data suggest that the early and mid-term results of partial aortic root remodeling were favorable, and it restored valve durability and function. Thus, the use of technique for root reconstruction in patients with acute type A dissection should be vigorously encouraged.

A seventh-order model for dynamic response of an electro-hydraulic servo valve

In this paper, taking two degrees of freedom on the armature–flapper assembly into account, a seventh-order model is deduced and proposed for the dynamic response of a two-stage electro-hydraulic servo valve from nonlinear equations. These deductions are based on fundamental laws of electromagnetism, fluid, and general mechanics. The coefficients of the proposed seventhorder model are derived in terms of servo valve physical parameters and fluid properties explicitly.For validating the results of the proposed model, an AMESim simulation model based on physical laws and the existing low-order models validated by other researchers through experiments are used to compare with the seventh-order model. The results show that the seventh-order model can reflect the physical behavior of the servo valve more explicitly than the existing low-order models and it could provide guidance more easily for a linear control design approach and sensitivity analysis than the AMESim simulation model.

Hypercoagulability existing in the local left atrium of patient with mitral stenosis

Objective To investigate the pathogenesis of thromboembolism in patients with mitral stenosis in a pre-thrombotic state.Methods The biochemical markers’ levels in plasma for platelet activity [soluble P-selectin (GMP-140)],states of thrombin generation [antithrombin Ⅲ (AT Ⅲ) and protein C (PC)],fibrinolysis [D-dimer (DD), plasminogen activator inhibitor 1 (PAI-1),tissue plasminogen activator (t-PA) and FDP] and von Willebrand factor (vWF) were determined from blood specimens obtained from the femoral veins and arteries and the right and left atria of 43 consecutive patients (20 with atrial fibrillation and 23 with sinus rhythm) with mitral stenosis (MS),undergoing percutaneous mitral valvuloplasty. The same parameters were compared with those of 15 control subjects,who had no detectable heart disease,but with paroxysmal supraventricular tachycardia undergoing radiofrequency catheter ablation of the left accessory pathway through a transseptal passage. Results Blood from the left atrium contained an excessive amount of platelet activity,thrombin generation and fibrinolysis compared with the blood from the right atrium,and the femoral veins and arteries. However blood from the right atrium was much lower in these activities when compared with those from the left atrium,and the femoral veins and arteries in both groups. Compared with those in the control subjects, GMP-140 in the left atrium was significantly higher ( P <0.05) and AT Ⅲ was significantly lower ( P <0.05) in patients with MS. Compared with the patients with MS and spontaneous left atrial echocontrast (LASEC)≤1,the patients with MS and LASEC≥2 had significantly higher levels of GMP-140 in plasma ( P <0.05),and significantly lower levels of AT Ⅲ ( P <0.05) and PC ( P <0.01) levels in the left atrium. However, there were no significant differences between patients with atrial fibrillation and those with sinus rhythm regarding amounts of plasma coagulation markers in the left atrium. Univariate regression analysis revealed that LASEC was negatively correlated with plasma levels of blood from the left atria in the patients with MS. Conclusion Coagulability is increased in the left atria of patients with MS and is positively correlated with LASEC.