The heart valve prosthesis must have excellent hydrodynamic performance which is usually tested in vitro, not in vivo. This paper comprehensively introduced the principles and methods of hydrodynamic performance in vitro testing, helping clinicians to understand valve performance parameters, evaluate valve applicability, and reduce clinical risk of the valve prosthesis. In vitro testing not only serves as the "gold standard" for valve prosthesis assessment, but also provides detailed data for design and optimization of the prosthesis. ISO 5840 defines the items and methods for valve in vitro testing, which consists of three parts: (1) pulsatile flow testing, which reproduces the pulsating flow of the valve prosthesis after implantation in the human body; (2) steady flow testing, which assesses valve forward flow resistance; (3) durability testing, which evaluates the durability of the valve prosthesis and determines the expected failure mode. In addition, the paper presented the differences between atrioventricular and aortic valve testing, the method of mitral valve testing, the differences between transcatheter and surgical valve testing, and the method of valve flow visualization.
Abstract： Objective To analyze risk factors associated with postoperative respiratory failure in patients with valvular surgery. Methods Between January 2001 and November 2010, clinical data of 618 patients with 339 males and 279 fameles at age of 10-74（44.01±13.95）years,undergoing valvular operations were investigated retrospectively. We divided the patients into two groups according to the presence （74 patients）or absence（544 patients）of postoperative respiratory failure. Its risk factors were evaluated by univariate and multivariate logistic regression analysis. Results The hospital mortality rate of valvular surgery was 6.1%（38/618）.The morbidity rate of respiratory failure was 12.0%（74/618） with hospital mortality rate at 17.6%（13/74） which was significantly higher than those patients without postoperative respiratory failure at 4.6%（25/544, χ2=18.994, P=0.000）. Univariate analysis showed age＞ 65 years（P=0.005）, New York Heart Association（NYHA）classⅣ（P=0.014）, election fraction＜ 50.0%（P=0.003）, cardiopulmonary bypass time＞ 3 h（P=0.001）, aortic cross clamping time＞ 2 h（P=0.008）, concomitant operation（ valvular operation with coronary artery bypass grafting, Bentall or radiofrequency ablation maze operation（P=0.000）, reoperation（P=0.012）, postoperative complications （P=0.000）, and blood transfusion＞ 2 000 ml（P=0.000） were important risk factors for postoperative respiratory failure. Multivariate logistic regression showed that concomitant operation（P=0.003）, reoperation（P=0.010）, postoperative complications（P=0.000）, and blood transfusion＞2 000 ml（P=0.012）were significant independent predictive risk factors. Conclusion This study suggest that patients with predictive risk factors of postoperative respiratory failure need more carefully treated. The morbidity of these patients would be reduced through improving perioperative management, shortening cardiopulmonary bypass time and reducing postoperative complications.
The pulsatile flow experiment can not only evaluate the preclinical safety and risk of prosthetic heart valve (PHV) but also play an important role in the computational model and fluid simulation, providing an experimental basis for the performance optimization of PHV. This paper mainly reviews the development and the latest progress of PHV pulsatile flow experiments and the characteristics of experimental pulse duplicator, and discuss the research direction of pulsatile flow experiments, expecting a further development in this field.
ObjectiveTo investigate whether there is a protecting effect of remote ischemic preconditioning (RIPC) on patients underwent cardiac valvular surgery. MethodWe retrospectively analyzed the clinical data of 72 adult patients underwent cardiac valvular surgery in our hospital from Febuary 2014 through April 2015 year. There were 26 males and 46 females with an age ranging from 23-68 years. We devided 72 patients into a RIPC group and a control group. There were 14 males and 28 females with a mean age of 48.87±12.28 years in the RIPC group. After the induction of anesthesia, the RIPC group was induced by three cycles of right upper limb ischemia and reperfusion using a blood pressure cuff. The blood pressure cuff was inflated to 200 mm Hg and we held it on for 5 minutes, deflated to 0 mm Hg and maintained for 5 minutes, which was defined as one cycle. There were 10 males and 20 females with a mean age of 47.70±8.07 years in the control group. We placed a standard blood pressure gasbag on the right upper limb for 30 minutes without inflation in the control group. We recorded the clinical data including cardiopulmonary bypass (CPB) time, the cross-clamping time of ascending aorta, preoperative ejection fraction (EF), EF after discharging, postoperative complica-tion and mortality. Blood were sampled preoperatively (T0), 30 minutes after RIPC (T1), 30 minutes aftr the cardiopul-monary bypass finished (T2), 24 hours (T3), 48 hours (T4) and 72 hours (T5) after surgery to detect the concentration of troponin T (cTnT) and creatine kinase-MB (CK-MB). We counted the person-time used dopamine and norepinephrine. ResultThere was no death in both groups. The mechanical ventilation time, the time of ICU stay, the time of hospital stay, the number of person used vasoactive agent, and the EF when discharging showed no statistical difference between the two groups. Levels of cTNT in the RIPC group were statistically lower than those in the control group at T2 and T3 (P=0.001, P=0.001). Levels of CK-MB in the RIPC group were statistically lower than those in the control group at T2, T3, and T4 (P=0.011, P=0.010, P=0.033). ConclusionRIPC may have protective effect on myocardium for patients underwent cardiac valvular surgery.