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@#Objective To discuss the feasibility of establishment of animal model of "functional" bicuspid aortic valve with swine and observe its effect on the wall shear stress inside the aorta. Methods Four common Shanghai White Swine with body weight between 50 kg to 55 kg were selected. Under general anesthesia and cardiopulmonary bypass, the aortic transverse incision approach was used, continuous suture with 6-0 polypropylene to align the left and right coronary valve leaflets to create a bicuspid valve morphology. After the operation, echocardiography was used to observe the aortic valve morphology and the hemodynamic changes of the aortic valve orifice. The effect on the wall shear stress inside the aorta was studied with 4D-Flow magnetic resonance imaging (MRI). Results A total of 4 swine "functional" bicuspid aortic valve models were established, with a success rate of 100.0%. Echocardiography showed that the blood flow velocity of the aortic valve orifice was faster than that before the operation (0.96 m/s vs. 1.80 m/s). 4D-Flow MRI showed abnormally increased wall shear stress and blood flow velocity in the aorta of the animal models. After the surgery, in model animals, the maximal wall shear stress inside the ascending aorta was greater than 1.36 Pa, and the maximum blood flow velocity was greater than 1.4 m/s. Conclusion Establishment of the animal model of "functional" bicuspid aortic valve in swine is feasible, scientific and reliable. It can be used in researches on evaluating the pathophysiological changes.
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Late tricuspid regurgitation after left-sided valve surgery can negatively affect long-term prognosis. The surgical timing and strategy of tricuspid valve reoperation will have important impact on the surgical outcomes. However, there is no clear recommendations of the surgical timing for this condition in the current guidelines. Generally, tricuspid valve reoperation should be performed before irreversible right heart failure occurs. Although tricuspid valve repair is the first choice for tricuspid regurgitation, bioprosthetic tricuspid valve replacement might be a reliable alternative when tricuspid leaflets have severe rheumatic damage or right ventricle and tricuspid annulus significantly dilate. Combined minimally invasive surgical techniques, including right minithoracotomy approach, accessing the right atrium directly through the pericardium with limited dissection, peripheral cannulation strategy with the vacuum-assist single venous drainage technique and heart beating technique, can significantly decrease the operative mortality and postoperative bleeding. With development of interventional therapy, transcatheter tricuspid valve repair or replacement may become alternatives for tricuspid regurgitation after left-sided valve surgery in the future.
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Objective@#To examine the short-term outcomes of minimally invasive reoperation for severe tricuspid regurgitation after left-sided valve surgery.@*Methods@#From January 2015 to December 2018, a total of 89 patients with severe tricuspid regurgitation after left-sided valve surgery received reoperation in Department of Cardiovascular Surgery, Zhongshan Hospital, Fudan University were included in this study. There were 21 males and 68 females, aging of (56.4±7.9) years (range: 41 to 74 years). The interval between previous left-sided valve surgery and tricuspid reoperation was (14.1±6.1) years (range: 4 to 33 years). A combination of multiple minimally invasive techniques were adopted, including endoscopy-assist right minithoracotomy approach, peripheral cannulation strategy with the vacuum-assist single venous drainage technique, heart beating technique, and temporary percutaneous pacemaker implantation, with a concomitant enhancement in preoperative right cardiac function optimization.@*Results@#All patients received minimally invasive isolated tricuspid valve replacement (n=81) or tricuspid valve repair (n=8). After the application of multiple minimally invasive techniques, the operative mortality rate was only 3.4% (3/89). The causes of death were progressive right heart failure with multiorgan failure (n=1) and low cardiac output associated with postoperative bleeding (n=2). Regarding to the perioperative complications, renal replacement therapy rate was 5.6% (5/89), permanent pacemaker implantation rate was 1.1% (1/89), and the incidence of stroke was 0. Mechanical ventilation time was 24(24) hours, ICU stay time was 2.5 (3.0) days (M(QR)). During the short-term follow-up, there were no case of severe tricuspid regurgitation, 2 cases of moderate regurgitation, 4 cases of mild-to-moderate regurgitation.@*Conclusions@#For severe tricuspid regurgitation after left-sided valve surgery, the advanced minimally invasive techniques can significantly reduce the operative mortality and morbidity. Minimally invasive bioprosthetic tricuspid valve replacement is a reliable alternative for severe tricuspid regurgitation after left-sided valve surgery.