Mechanical valves and bioprostheses are common valve types used in aortic valve replacement. However, both are known to have inherent advantages and disadvantages. Mechanical valves, for example, offer long term durability but are thrombogenic, necessitating life long anticoagulation that carries an increased risk of haemorrhage. In contrast, bioprostheses are less thrombogenic, which in most patients obviates the need for long term anticoagulant agents; however, their propensity to undergo structural valvar deterioration (SVD) limits their durability. The risk of haemorrhage with mechanical valves and the risk of SVD in bioprostheses are age dependent, the first increasing and the latter decreasing with advancing age. Consequently, the choice between a mechanical valve and a bioprosthesis for a given patient undergoing aortic valve replacement involves striking a balance between the risks and benefits of each valve type. Thus a knowledge of the outcomes after aortic valve replacement for each type of valve could assist surgeons in their choice of valve. Microsimulation and associated simulation techniques are capable of providing insight into outcomes after aortic valve replacement. We therefore combined meta-analyses of several clinical studies with microsimulation to study the outcomes of patients after aortic valve replacement with bileaflet mechanical valves and stented porcine bioprostheses.
They are the most long-lasting type of replacement valve, and most of these manufactured valves will last throughout the remainder of the patients’ lifetime.Patients who receive a manufactured valve will nearly always require a blood thinning medication throughout the remainder of their lives. The blood thinner will keep clots from forming, which is critical for the person with a mechanical valve because clots can lodge in the valve flaps or hinges and cause a malfunction. Clots can also break off and form into an embolism (traveling clot), which may move through the bloodstream and lodge into a vessel where it may eventually lead to problems like or .Donor Valve ImplantationA human donor valve is the least common choice and it’s most often used for someone who is suffering from an illness that affects the valve, such as . A donor valve can be expected to last 10-20 years.Tissue Valve (sometimes called ‘bioprosthetic’ valves)Tissue valves are created from animal donors’ valves or other animal tissue that's strong and flexible.
Quadricuspid Aortic Valve: A Comprehensive Review - …
Background: Mechanical valves and bioprostheses are widely used for aortic valve replacement. Though previous randomised studies indicate that there is no important difference in outcome after implantation with either type of valve, knowledge of outcomes after aortic valve replacement is incomplete.
used on the Mosaic™ bioprosthesis and the Freestyle™ Aortic Root ..
The model predicted a life expectancy of 10.4 and 10.8 years, respectively, for a 65 year old man following implantation with a mechanical valve and a stented bioprosthesis. Considering life expectancy, the age crossover point between either valve type was 59 years. This result concurs well with the results of Birkmeyer and colleagues, who used a Markov state transition model to simulate the prognosis of patients with aortic valve replacement. They obtained a crossover point of 60 years. The microsimulation model also calculates the EFLE after aortic valve replacement. For the 65 year old male patient, for example, the model predicted an EFLE of 7.7 and 8.4 years, respectively, for mechanical valves and bioprostheses. Considering EFLE, the age crossover point between either valve type was 60 years.
VALVE REPLACEMENT WITH MECHANICAL VALVES.
Simulation methods are widely used in operations research and management science. A well known example of a simulation program is the flight simulator in the aviation industry. Although not commonly used in clinical medicine, simulation models have been used previously to determine the prognosis of patients after aortic valve replacement. We have designed a microsimulation model which calculates the outcomes of patients after aortic valve replacement. Compared with standard statistical techniques, the added value of microsimulation is that it allows modelling of the complex outcome pathways resulting from the many simultaneous risks, and provides detailed insight into the outcomes of patients following valve replacement, deducible to the individual patient. The structure of the model incorporates a schematic representation of the lives of patients with aortic valve replacement (fig 1) and, in principle, the model can be applied to any valve type. For this analysis, data from meta-analysis of published reports were incorporated into the model to predict the outcomes of patients after aortic valve replacement with bileaflet mechanical valves and stented porcine bioprostheses, respectively.
Comparison of outcomes after aortic valve replacement …
The lifetime risks of the more common valve related events are depicted in fig 3. As seen in fig 3A, the lifetime risk of SVD following a bioprosthesis reduces with advancing age at implantation, and is about 10% for a 75 year old patient. For the mechanical valves, the decreasing risk of thromboembolism with advancing age at implantation, concomitant on a decreasing life expectancy, is opposed by an increasing risk of haemorrhage (fig 3B). When considering the lifetime risk of experiencing at least one valve related event, the age crossover point for aortic valve replacement was 63 years.