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:Since 1978 the definition of prosthesis-patient mismatch（PPM） was first introduced by Rahimtoola, it has attracted the attention of foreign researchers. The PPM phenomenon is concerned to be an important factor which will affect patients＇ survival rate and quality of life. Till now, a lot of effort should still be put on this problem. But unfortunately, this problem is still being neglected in our country. This paper is a review of PPM from it＇s many aspects, such as definition, current research status, prevention, and it＇s research prospect. We hope this paper will intensify the clinicians＇ knowledge on PPM.
ObjectiveTo analyze the reason and prevention of late bioprosthetic heart valve thrombosis (LBVT). MethodsBioprosthetic heart valves were implanted in 580 patients between January 2001 and July 2013 in Changhai Hospital, and only found one case of LBVT (0.2%). Reoperation was performed for a 67-year-old male patient 3 years after bioprosthetic aortic valve replacement due to severe aortic valve stenosis. Retrospectively analyzed the clinical data and reviewed the literature between January 1989 and December 2013 in Pubmed. ResultsNo risk factor for thrombosis was revealed in this patient. Pathology revealed valve thrombosis and collagen and elastic fibers fragmentation and disruption in valve leaflets. In literature review, 20 articles and 47 cases were brought in. The morbidity of LBVT was 0.2%-1.0%. At least 18 patients had high risk factors, and 15 of the 18 patients discontinued anticoagulation after 3 months. However, at least 10 patients had no high risk factors. Forty-four of the 47 patients received stented porcine valve replacement, only one patient received stented bovine pericardial valve replacement. ConclusionsLBVT is a rare but serious complication after bioprosthetic valve replacement, the causes of which include the feature of the patients and the bioprosthetic valves. Bovine pericardial valves could be superior to porcine valves in preventing LBVT. Postoperative long-time aspirin therapy is recommended for patients without high risk factors. Patients with any high risk factors should prolong anticoagulation.
Objective To introduce a new type of bileaflet mechanical prosthetic heart valve （GK bileaflet valve）and evaluate clinically the early hemodynamic effect and short term follow-up after its replacement. Methods Sixty-one patients with heart valve diseases were operated upon. The mitral valve replacement was performed in 34 patients, aortic valve replacement in 16 patients and double valve replacement in 11 patients. A total of 72 GK bileaflet mechanical valves were implanted, 45 in mitral position, and 27 in aortic position. Blood consistency and hemodynamics were monitored. Follow-up was carried out routinely to check whether there were some valve-related complications. Results There was no early mortality （〈30 d）. Only one patient died of trauma 2 months after the operation. Follow-up was 100% and extended 1 to 2. 5 years. Without valve-related complications all patients had lived for more than 1 to 2.5 years. In 98% （60/61） of survivors heart functional performance had improved to New York Heart Association class Ⅰ or Ⅱ . Conclusion Early clinical results and short term follow up demonstrate that GK bileaflet prosthetic heart valve exhibits excellent hemodynamic properties, satisfied blood consistency and a low incidence of valve-related complications. Midterm and long-term results should be observed further.
Valvular heart disease is a structural or functional disease of the heart due to rheumatic fever, congenital malformation, infection, or trauma, resulting in abnormal cardiac hemodynamics and ultimately heart failure. Implantation of artificial heart valves has become the main way to treat heart valvular disease. Because the structure of the artificial heart valve plays a key role in the stress distribution and hemodynamic performance of the valve and stent, the geometric configuration of the artificial heart valve is constantly updated and improved during its development from mechanical valve to biological valve, which closely mimics the geometric characteristics of the normal natural heart valve. This article sums up the design process of geometric configuration of artificial heart valves and the influence of geometric configuration on the central disc stress and durability of artificial heart valves, analyzes the important parameters of geometric modeling for artificial heart valves, and discusses the development of the corresponding modeling method, to provide reference and new ideas for the biomimetic optimization design of artificial valves.
Abstract: Objective To investigate the anticoagulation effect of warfarin on pregnant women with prosthetic mechanical heart valves during the whole course of pregnancy and their fetuses. Methods Followup survey was carried out on 103 pregnant women with prosthetic mechanical heart valves treated in the Second Xiangya Hospital of Central South University from April 1998 to June 2010. Their age ranged from 19 and 38 years (26.4±3.8 years). All the 103 pregnant women were given oral administration of warfarin during the whole course of pregnancy. The average dose of domestic warfarin was 3.30±0.43 mg/d (87 cases), while the average dose of imported warfarin was 2.90±1.05 mg/d (16 cases). Results None of the patients suffered from serious embolic events. One patient suffered from spontaneous peritoneal hemorrhage. There were 4 cases of intrauterine deaths, and 5 cases of fetal malformation including 1 case of Down’s syndrome and 4 cases of hydrocephalus. Six cases of low birth weight infants and 1 case of ABO hemolytic disease were also found. All the other neonates were healthy with normal weight. No pregnant women suffered from postpartum hemorrhage. Conclusion Oral administration of low dose warfarin (lt;5 mg/d) during the whole course of pregnancy is a relative safe and effective anticoagulation protocol.
The possibility of polyoxymethylene (POM) as heart valve leaflet material was investigated by comparing the hemocompatibility with that of 316L stainless steel and low-temperature isotropic pyrolytic carbon (LTIC). Surface hydrophobicity was characterized by water contact angle measurement.Platelet adhesion, APTT/PT/TT and hemolysis rate tests were applied for evaluating hemocompatibility. The results showed that POM was hydrophobic and had a low hemolytic rate, adhesion amount and activation degree of platelets on POM surface were less than 316L stainless steel, and was similar to LTIC. This research pointed out potential application of POM as heart valve leaflets.
Heart valve replacement is the major surgical treatment of severe valvular diseases. Due to the durability and reoperation-free, mechanical valves are widely used. Bioprosthesis valves became popular recently because of long service life and no demand for lifelong anticoagulation. However, how to choose the appropriate prosthetic heart valves, especially the application of bioprosthesis valves for patients at 55 to 65 years is still a major problem. This review focuses on more effective and scientific basis for rational choice of mechanical and bioprosthesis valve.