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Biological vs Mechanical Valve Use in Aortic Valve Replacement in the ElderlyAllison ChuladaUniversity of New HampshireNURS 612: Care of the Adult with Acute Illness IIBiological vs Mechanical Valve Use in Aortic Valve Replacement in the ElderlyAortic valve replacement surgery can be done to fix the problems of either aortic stenosis or aortic regurgitation. These complications can develop from congenital aortic valve disease or from acquired aortic valve disease. Acquired aortic valve disease can result from changes in the structure of the valve; common conditions include rheumatic fever and infective endocarditis. In the older adult, the most common cause of aortic stenosis is aortic valve degeneration. With time the aortic valve leaflets degenerate and become calcified. This creates the problem of getting the blood out of the heart to the rest of the body since the valve is narrowed, leading the patient to have hypotension and symptoms such as fainting and chest pain due to the lack of blood flow. Depending on the severity of the problem, aortic valve disease can be treated by either valve repair or replacement. In valve replacement there are two types of valves that can be used, mechanical or biological. A biological valve is made up of tissue from a cow, pig, or pericardial tissue from another species, while a mechanical valve is completely made from mechanical parts that are tolerated well by the body. A successfully inserted biological valve normally lasts about 10-15 years before it needs to be repaired or replaced; however, a mechanical valve can last a lifetime, but it also requires that the recipient be on a lifelong anticoagulant, such as Coumadin, to reduce the risk of blood clots (Svensson). In the elderly, surgery is always something that must be considered substantially because of the potential risk of complications such as DVT or hospital acquired pneumonia due to decreased mobility and their prolonged recovery time from their aging body systems. This paper will explore if the use of a mechanical valve or a biological valve would be more effective in treatment of the elderly and if the use of one versus the other would potentially be more beneficial in improving their quality of life. When searching for information and studies for this topic, I started by using the search engine Google and typing in “aortic valve replacement”. I read a few different articles to get the background information and establish a good base of the topic and also understand the main differences between mechanical and biological valves. Then I decided to use the databases of CINAHL, MEDLINE, and PubMed. From started broad and typed the key words of “aortic valve”, biological” and “mechanical” afraid I was not going to yield any results; however, I was wrong. Hundreds of results appeared so I narrowed down my search my adding more key words into each data base. I entered in “aortic valve replacement”, “biological”, “mechanical”, and “elderly”. I yielded 3 results from CINAHL, 19 from MEDLINE, and over 100 from PubMed. In order to narrow down the results on the PubMed database I added in the key word of “treatment” used the limits of English only, age greater than 65, and publication date of less of 5 years. This brought the results down to 30, so I started to sift through the articles on each database and found three common studies that matched the criteria of what my questions was asking. When choosing these three studies, I made sure that the studies were published within the past 10 years. I read the abstracts of each study and made sure that the population representative of each study matched the population I intended to target and that the objectives of each article matched what I was planning to answer by writing this paper. The patients needed to have undergone an aortic valve replacement, and the article had to compare the use of a mechanical versus a biological valve. Long-Term Safety and Effectiveness of Mechanical versus Biologic Aortic Valve Prostheses in Older PatientsThe purpose of the study was to evaluate the long-term mortality and valve-related complications in older individuals treated with bioprosthetic versus mechanical aortic valves. The researchers identified a cohort of Medicare-linked fee-for-service patients between 65 and 80 years of age undergoing elective or urgent aortic valve replacement with a mechanical or biological prosthesis from January 1, 1991, to December 28, 1999. Each patient, therefore, had at least 8 years of available follow-up data. When performing the statistical analysis, the Mantel-Haenszel test was used to compare the distribution of categorical variables between groups, whereas the Wilcoxon rank sum test was used to compare continuous variable distributions (Brennan).The results showed that biological (or bioprosthetic) valves were used with an increasing frequency in older adults, and within the study had a 20% increase of use over the timespan of research. The analysis of this research produced results in five different categories to compare between the use of biological or mechanical valves: all-cause mortality, aortic valve reoperation, stroke, bleeding, and endocarditis. All-cause mortality after AVR was 70.5% for patients who received bioprosthetic valves and 60.3% for those who received mechanical valves. By 12 years, reoperation was observed in 5.2% of patients with bioprosthetic valves and 2.3% of those with mechanical valves, showing that reoperation was more common in biological valves than in mechanical valves. The incidence of stroke was significantly lower among patients with bioprosthetic valves than among those with mechanical valves. Re-hospitalization for a bleeding event occurred in 15.5% of patients with bioprosthetic valves and 21.8% of those with mechanical valves. Although the incidence was low, endocarditis was diagnosed in 2.2% of patients given bioprosthetic valves and 1.4% of those given mechanical valves (Brennan). One of the strengths of this study was that it had one of the largest study cohorts, totaled at 39,199 participants, for this research topic, mean that a wide range of individuals with different comorbidities were obtained for this research and could give myriad data for provide sufficient results. Although use of the 1991 to 1999 data ensured that all patients had a minimum of 8 years of follow-up, the recent advances in bioprosthetic and mechanical valve technology may have altered the treatment in contemporary practice, which could produce different results for the categories of comparison that were analyzed (Brennan). Mid-term outcome and quality of life after aortic valve replacement in elderly people: mechanical versus stentless biological valvesThe purpose of this study was to assess the benefit for patients older than 65 years of aortic valve replacement with stentless biological heart valves in comparison with mechanical valves. From April 1996 and March 2001, 392 patients older than 65 years underwent AVR with either a stentless bioprosthesis or a mechanical prosthesis, and follow up information was acquired in 2001 by a mailed questionnaire and completed by telephone interviews. Since the preoperative characteristics of the patients receiving the valves differed, a multivariate regression analysis was done (Florath). The results were broken up into four main categories with subcategories within each. The four main categories included pre-operative mortality and morbidity, mid-term survival, valve related morbidity, and quality of life. Overall, there was no difference between the biological and the mechanical valve in the amount of time a patient stayed in the intensive care unit, and there were no significant difference in the midterm survival after AVR between the two valves. The rate of prosthetic valve endocarditis was 0.6% and 0.3% per patient year in the stentless bioprosthesis and mechanical prosthesis groups, respectively. Patients with aortic stenosis receiving stentless bioprosthesis had a significant increased risk of reoperation. All patients receiving a mechanical valve required anticoagulation, whereas in the stentless bioprosthesis group, only 21% required this treatment for concomitant diseases. It was found that patients older than 75 years receiving mechanical valves had a nearly 19 times increased risk of bleeding events; the risk of bleeding is significantly higher in patients with mechanical valves older than 75 years of age, and there is still greater chance of bleeding in mechanical valves than biological valves in patients under 75, but the risk is not as high. This study found that the risk of stoke was 3.2% and 1% per patient year for stentless the bioprosthesis and the mechanical prosthesis groups, respectively. After receiving the feedback from the questionnaire, patients requiring anticoagulation had nearly a twofold increased risk for an impaired emotional reaction (Florath).This study was able to receive input from patients who underwent AVR and gather data about their quality of life since the operation. This is an important strength because it is able to add an additional factor to the research other than the medical effects the valve will have on the participants. Like the first study, this study received follow up information from 2001, and the progression of technology with mechanical and biological valves has come a long way; this could potentially generate different treatment results (Florath). Aortic Valve Replacement in the Elderly: Determinants of Late OutcomeThe purpose of this study was to evaluate the outcomes of elderly patients (older than 70 years of age) after AVR and focus on the identification of patients with increased longevity and the potential impact of valve type on overall survival. The study involved 2890 consecutive patients over 70 years of age who underwent aortic valve replacement surgery between 1993 and 2007. Their data was reviewed retrospectively, analyzed, and stratified by preoperative and intraoperative variables (Ashikhmina).Results show that there is no statistical significant difference in overall survival for patients with mechanical versus biological valves, but there was a trend toward increased longevity in patients with mechanical valves. Again, this study at a large sample size, which allowed for superfluous data and could therefore generate respected results. Since it was a retrospective review of prospectively gathered data, and its accuracy depended on the availability of information within the medical records. Another limitation was that overall survival was analyzed, and not valve-related or cardiac-related mortality, because the cause of death for some patients was unknown, and this information could have been vital for the research of the effectiveness of the valve (Ashikhmina). When starting this research paper, I asked the question how does the use of a biological valve in AVR affect the effectiveness of treatment compared to the use of a mechanical valve in older adults. Valve degeneration is common among older adults since the valve has been working in the body for so long, and like many other organs starts to wear out as a person ages. Quality of life and long term outcomes, such as infection, reoperation, stroke, and bleeding are very important factors of consideration when operating on an older adult, and if the incidence of these can be decreased with the use of a certain valve, or the quality of life can be enhance by the use of a biological or mechanical valve, then it would be evident that this valve should be used. However, the evidence from the current research states that there is no statistical significance to prove that the use of one valve is better than the other. There are factors of each valve that can make them seem more appealing, such that those having AVR with a biological valve have a decreased risk for bleeding and stroke, while those who receive a mechanical valve have a decreased risk for endocarditis and reoperation. One major difference between the mechanical valve and the biological valve that older adults report affects their quality of life is the lifelong medication adherence to an anticoagulant, usually Coumadin, to prevent blood clots.There are risks with any operation that a person decides to undergo. When it comes to the decision between a mechanical or biological valve or an aortic valve replacement, research has shown that one valve is not significantly better than the other. Based on the evidence synthesized, older adults who are concerned with medication adherence or who have trouble following a medication or dietary schedule should look into the use of a biological valve. Although reoperation is more common in these types of valves, the incidence is still extremely low and very rare for the given population seeing as how these valves typically last between 10-15 years. Once a patient undergoes AVR, regardless of the valve, it is essential that prophylactic antibiotics are taken before dental appointments to decrease the risk for endocarditis. The patient will most likely already have an established relationship with a cardiologist, and echocardiograms will be done to assess the function of the valve and the effectiveness of the treatment. ReferencesAshikhmina, E., Schaff, H., Dearani, J., Sundt, T., Suri, R., Park, S., & ... Daly, R. (2011). Aortic valve replacement in the elderly: determinants of late outcome. Circulation, 124(9), 1070-1078. doi:10.1161/CIRCULATIONAHA.110.987560Brennan, J., Edwards, F., Zhao, Y., O'Brien, S., Booth, M., Dokholyan, R., & ... Peterson, E. (2013). Long-term safety and effectiveness of mechanical versus biologic aortic valve prostheses in older patients: results from the Society of Thoracic Surgeons Adult Cardiac Surgery National Database. Circulation, 127(16), 1647-1655. doi:10.1161/CIRCULATIONAHA.113.002003Florath, I., Albert, A., Rosendahl, U., Alexander, T., Ennker, I., & Ennker, J. (2005). Mid term outcome and quality of life after aortic valve replacement in elderly people: mechanical versus stentless biological valves. Heart (British Cardiac Society), 91(8), 1023-1029.Svensson, L., Gillinov, M., & Mihaljevic, T. (n.d.). Cleveland Clinic - Heart Surgery - Aortic Valve Surgery. Cleveland Clinic. Retrieved May 24, 2014, from ................
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