PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “HEART VALVES”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 793 records · Page 44Linked to original sources
PubMed2004

Bioprosthetic heart valves: the need for a quantum leap.

More than 250,000 bioprosthetic heart valves are being implanted annually. Although the majority of recipients are elderly developed-world patients, the most urgent need for tissue valves is in younger patients, where rapid degeneration of contemporary prostheses remains a serious obstacle. After decades of empirical and mostly futile attempts to extend the longevity of tissue valve prostheses, new insights and solutions are on the horizon. Aetiologically, a shift of focus from mineralization to immune responses and inflammation emerges. On the development side, new engineering approaches to both selective extraction of tissue components and cross-links are increasingly defining the new direction. In order to dramatically improve the performance of bioprosthetic heart valves, these new developments need to lead to a broad consensus for a paradigm shift in a hitherto rather stagnant field of medical research.

Animals↗
PubMed2001

Self-management of oral anticoagulant therapy for mechanical heart valve patients.

OBJECTIVE: Self-management of oral anticoagulant therapy (OAT) has shown good results on a short-term basis. We hypothesize that self-management of OAT provides a better quality of treatment than conventional management also on a long-term basis. The aim of this study was to assess the quality of self-management of OAT in patients with mechanical heart valve prostheses on a 4-year perspective in a prospective, non-randomized study. DESIGN: Twenty-four patients with mechanical heart valves and on self-managed OAT were followed for up to 4 years. A matched, retrospectively selected group of conventionally managed heart valve patients (control group) was used as reference. RESULTS: The median observation time was 1175 days (range: 174-1428 days). The self-managed patients were within therapeutic INR target range for a mean of 78.0% (range: 36.1%-93.9%) of the time compared with 61.0% (range 37.4%-2.9%) for the control group. CONCLUSION: Self-management of OAT is a feasible and safe concept for selected patients with mechanical heart valve prostheses also on a long-term basis. It provides at least as good and most likely better quality of anticoagulant therapy than conventional management assessed by time within the therapeutic International Normalized Ratio (INR) target range.

Administration, Oral↗
PubMed2003

Experience with enoxaparin in patients with mechanical heart valves who must withhold acenocumarol.

OBJECTIVES: To evaluate the incidence of thromboembolic and haemorrhagic events in a cohort of patients with mechanical heart valves who had to withhold acenocumarol and were treated with enoxaparin. DESIGN: Observational prospective study. SETTING: In hospital; after discharge, and follow up by telephone call. PATIENTS AND METHODS: All consecutive patients with mechanical heart valves admitted to the authors' hospital between May 1999 and January 2002 who had to interrupt treatment with acenocumarol and were treated with enoxaparin as an alternative to other methods were enrolled. In each patient, the following characteristics were prospectively determined: the reason for interrupting acenocumarol, demographic data, estimated global risk for thromboembolic events, international normalised ratio before starting enoxaparin treatment, number of days taking enoxaparin, and mean level of anti-Xa activity during treatment. All patients were followed up through clinical history during the hospitalisation and by telephone after discharge to detect thromboembolic events. MAIN OUTCOME MEASURE: Presence of thromboembolic or haemorrhagic events. RESULTS: 82 patients were identified and followed up for a mean of 2.8 months (range 1.5-3.5 months) after discharge. 61 of them (74%) had one or more associated thromboembolic risk factors. Acenocumarol was interrupted (to perform an invasive procedure in 74 patients and because of haemorrhagic complication in 8) an average of 11.2 days (range 3-40 days). Most patients received the standard enoxaparin dose (1 mg/kg at 12 hour intervals). Mean (SD) anti-Xa activity was 0.58 (0.3) IU/ml (median 0.51). There were 8 minor and 1 major bleeding events during enoxaparin treatment. No thromboembolic complications were clinically detected during hospitalisation or during follow up (95% confidence interval 0% to 3.6%). CONCLUSIONS: Enoxaparin may be an effective and relatively safe substitute anticoagulant for patients with mechanical heart valves who must withhold acenocumarol.

Acenocoumarol↗
PubMed1994

[Potential cornea, heart valve, bone and skin donors in 5 Dutch hospitals far outnumber actual donors].

OBJECTIVE: To determine the number of potential cornea, heart valve, bone and skin donors among patients who died in Dutch hospitals, in comparison with the number of actual donors. DESIGN: Descriptive. SETTING: Five hospitals in the western part of the Netherlands. MATERIAL AND METHODS: The medical records of patients who died in 1989 were reviewed. Children younger than 4 weeks were excluded from the study. On the basis of criteria used by the Eurotransplant and Bio Implant Services Foundations and those of the skin bank of the Dutch Burns Foundation, it was determined if the deceased were medically suitable as cornea, heart valve, bone or skin donor. RESULTS: Data were collected on 2150 of 2369 deceased (90.8%), mean age 69.5 (17.0) (SD) years. Medical criteria for cornea donation were met in 72% of the cases, 6.8% of these became actual donors. The figures for heart value donors were 4.3% and 9.7% respectively, and for bone donors 2.7% and 0%. The percentage of potential skin donors could not be determined, because essential data were missing from the medical records. After extrapolation the number of donors among all patients who died in Dutch hospitals in 1989 amounted to 35,046 potential cornea donors, 2,093 potential heart valve donors and 1,314 potential bone donors. CONCLUSION: Only a very small proportion of the potential tissue donors were referred to Eurotransplant and Bio Implant Services. Therefore, waiting lists for tissue transplantation are not necessary.

Adolescent↗
PubMed1996

Surface and edge wear of Björk-Shiley Delrin heart valve discs.

BACKGROUND AND AIMS OF THE STUDY: Wear of Björk-Shiley Delrin (BSD) heart valve discs is known to have occurred in some patients, possibly contributing to increased regurgitation. This paper specifically addresses surface and edge wear that have been observed on some discs of explanted BSD valves after implant durations up to 22.4 years. METHODS: The wear patterns have been documented using either photographic or scanning electron microscopic methods for 42 out of 73 explanted BSD valve discs. The remainder of the 73 discs were not available for analysis. RESULTS: One form of surface wear found on 18 out of 42 of the Delrin discs was the concentric wear of mild abrasive origin along the surface near the disc edge due to contact with the inlet and outlet struts. In five instances, surface anomalies were observed, primarily in the areas of high velocity blood flow. This paper also describes two Delrin discs with non-concentric edge wear patterns: (a) one which appears to be due to fatigue micro-chipping and abrasive wear of the disc of a 20 year BSD explant, which had fibrous tissue ingrowth, causing abnormal rotation of the disc during valve closure, and (b) a second one which is thought to have been caused by a cutting action of the knife-like stub of one inlet strut leg which had separated. Cross-sectional analyses of two explanted BSD discs, with full indent grooves on the inflow side, indicated that the Delrin material was primarily compressed under these wear grooves, rather than removed by abrasion. Hardness profiles indicated that the Delrin 150 microns below the surface was harder and would tend to prevent further deformation. A simple model describing the compound impact (impact with sliding) phenomenon is introduced to explain abrasive wear found on some explanted BSD discs. CONCLUSION: Based on the studies here and reports in the literature, the BSD heart valve appears to present a design which provides many years of service and, when wear occurs, it occurs in a manner that provides easily recognized clinical symptoms, which allow time for diagnosis and treatment.

Aortic Valve↗
PubMed1985

Magnetic resonance imaging of prosthetic heart valves.

To evaluate the safety of magnetic resonance (MR) imaging of prosthetic heart valves, nine different synthetic and tissue valves were studied ex vivo. Deflection was measured in 0.35-tesla (T) and 1.5-T superconducting magnets and at the edge of the bore of a 2.35-T electromagnet in field gradients of 5, 1.1, and 6.3 mT/cm, respectively. No valve deflected in the 0.35-T magnet; six synthetic valves deflected 0.25 degrees-3 degrees in the 1.5-T magnet; all valves deflected 1 degree-27 degrees at the edge of the 2.35-T magnet. Each valve was then submerged in a vial of water and the temperature was measured immediately before and after each of two spin-echo imaging sequences in the two superconducting magnets. No significant temperature rise followed exposure in either magnet. Image distortion varied from negligible to severe in both imagers; magnitude of distortion paralleled magnitude of deflection. These data suggest that patients with present-day prosthetic heart valves can be safely imaged in present-day MR imagers and that prosthesis-induced artifacts will not interfere with interpretation in most instances.

Bioprosthesis↗
PubMed1979

[Sanatorium stage in the rehabilitation of patients with rheumatic defects after heart valve prosthesis].

In 93.2% of 104 patients treated at a cardiological sanatorium after heart valve prosthetics the condition had improved by the time of discharge and only in 2.9% (3 patients) it had grown worse. The measures of rehabilitation comprised curative, physical, and psychologic aspects. The improvement in the condition of patients who had been operated on was attested by the results of ECG, polycardiography, and external respiration tests. The increased tolerance to physical load and the improved ability for coping with the tasks of every-day life are also objective indicators of the effectiveness of the stage of sanatorium treatment in the general complex of rehabilitation of patients who had been subjected to heart valve prosthetics.

Adolescent↗
PubMed2000

A mathematical analysis of hemorheological changes during heart valve replacement.

BACKGROUND: This study was carried out to establish a mathematical model in order to assess blood trauma and hemorheology during cardiopulmonary bypass and heart valve replacement. METHODS: Ten factors which represented blood trauma and hemorheology were investigated in fourteen patients undergoing mechanical heart valve replacement. RESULTS: The results confirmed that red blood cell damage was mainly dependent on cardiopulmonary bypass time and hematocrit level. Platelet aggregation was influenced by platelet count, plasma fibrinogen and cardiopulmonary bypass time, the cases with aortic valve replacement resulting in more platelet activation than the mitral valve replacement (p<0.05). High shear blood viscosity was significantly influenced by hematocrit, plasma viscosity and red cell filterability, while low shear blood viscosity was significantly related to hematocrit, plasma viscosity and fibrinogen concentration, which represented 68.5% and 74.8% of hemorheologic changes due to blood trauma respectively. CONCLUSIONS: The relationship between blood trauma and hemorheologic changes was evaluated and the potential areas for improvements in cardiopulmonary bypass techniques in relation to mechanical heart valve implantation were identified. These areas of technical and pharmacological development must reduce changes in all the possible plasma components especially fibrinogen and also preserve platelets and red cells from damage.

Adolescent↗
PubMed1985

Scanning electron microscopy studies of staphylococcal adherence to heart valve endothelial cells in organ culture: an in vitro model of acute endocarditis.

Organ cultures of human heart valves were used as a model to study the initial pathobiology of acute infective bacterial endocarditis. We used Staphylococcus aureus isolated from a case of infective endocarditis to infect the in vitro culture of the heart valves. Using scanning electron microscopy, we assessed the initial damage, attachment to and invasion of the endothelial cell layer by staphylococci. Our results indicate there is initial damage to the endothelium prior to observation of staphylococci attaching to the endothelial cell. By 12 h post infection, there is significant attachment and damage. At 24 h after infection, destruction of the heart valve endothelium is complete. The attachment and destruction are progressive events and can be correlated quantitatively with bacterial numbers from the culture medium and those attached to the valves. This is correlated with increasing adherence ratios of the attaching staphylococci.

Acute Disease↗
PubMed1986

[Benefits of endocarditis prevention in patients with prosthetic heart valves].

The beneficial effect of prophylaxis for IE was studied in 229 patients with prosthetic heart valves in whom 287 diagnostic or therapeutic interventions were performed. The prevention used was similar to that recommended by the American Heart Association. Prosthetic valve endocarditis was not observed in any of these patients. This result was compared with that of 304 patients with prosthetic heart valves, in whom without any prevention 390 similar interventions were performed during the same observation period. The incidence of prosthetic valve endocarditis occurring within 14 days after the intervention was 1.5/100 interventions (n = 6). All patients had to be reoperated. One patient died perioperatively. Two more patients developed prosthetic valve endocarditis 8 and 13 weeks, respectively, after the initial intervention. This retrospective study documents the benefit of the prophylaxis for IE used.

Anti-Bacterial Agents↗
PubMed2003

Mechanical heart valve patients can manage oral anticoagulant therapy themselves.

OBJECTIVES: Thromboembolism and anticoagulant related bleeding are still the most common complications in mechanical heart valve patients. Management of the oral anticoagulant therapy is therefore a key determinant for these clinical complications. We hypothesize that patients selected to self-managed oral anticoagulant therapy have a better treatment quality than patients in conventional oral anticoagulant therapy. The aim of this study was to assess the time within the therapeutic International Normalized Ratio (INR) target range and the incidence of clinical complications in our group of patients, and compare these data with published data on conventional management. METHODS: Mechanical heart valve patients (N=94) with a mean age of 47.6 years (range 4.2-76.6 years) were trained in home blood analysis of INR using a CoaguChek home coagulometer and coumarin dosage adjustment. After training, the patients were followed by weekly INR measurements. The therapeutic range was a target INR +/-0.5. The indications for initiating oral anticoagulant therapy were: aortic valve (N=62), mitral valve (N=29), tricuspid valve (N=1) and multiple valves (N=2). RESULTS: The mean observation time was 2.1 years (range 0.04-6.2 years), and the total number of patient-years was 197. The patients were within the therapeutic INR target range for a median of 76.0% (range 32.1-100.0%) of the time. There were two major thromboembolic events and five major bleedings events, comprised of two deep vein thromboses (both in the same patient), four episodes of epistaxis and one case of gastrointestinal bleeding. All the events required short hospitalization, and after treatment all the patients were discharged from the hospital without any sequelae or other complications. Using published work as references the expected number of major thromboembolic and bleeding complications in conventional management was four and 12, respectively. CONCLUSIONS: Self-management of oral anticoagulant therapy provides a good treatment quality for mechanical heart valve patients. We therefore consider self-management of oral anticoagulant therapy as an equally as good or potentially better treatment option for selected patients compared to conventional management.

Administration, Oral↗
PubMed1996

Donation of heart valve tissue: seeking consent and meeting the needs of donor families.

OBJECTIVE: To report on the experiences of senior social workers in seeking consent for donation of heart valve tissue at coronial autopsies. METHODS: Retrospective review of the records of an allograft heart valve program at a tertiary referral hospital in Brisbane between 11 October 1990 and 11 October 1995. RESULTS: Of the 305 families who could be contacted after the sudden death of a family member, 247 consented to donation (81%) and 58 did not (19%). In the context of coronial enquiries, a sensitive assessment of the counselling needs of potential donor families is necessary. Difficulties in seeking consent include: the sudden nature of the death and lack of information about the prospective donor and his/her family; and the limited time available for tissue retrieval as well as the necessity, in most cases, to obtain consent for donation by telephone. The needs of these families included information on autopsy, transplantation and recipient outcome; grief counselling; emotional and practical support; and recognition of their contribution. CONCLUSION: In this successful tissue donation program, senior social workers have maximised the availability of heart valve tissue for donation, while respecting the needs and wishes of potential donor families and helping them with their loss through counselling and assistance. The program has been extended to the retrieval of eye and bone tissue at coronial autopsies in Queensland.

Adult↗
PubMedDate not supplied

Fast method for the estimation of heart valve leaflet viability.

BACKGROUND: The assessing of heart valve viability is critical for the preparing of viable and implantable biological value. Non-viable valves should be cross-linked with various agents whereas viable tissues are suitable for cryoprotection. Cell viability assessment should be rapid, simple, easy and low cost. MATERIAL AND METHODS: A simple method, simultaneous fluorescent staining of both viable and damaged valve cells was described. The material was consisted of 2 groups: a) with ischemic time below 3 hours (5 swine valves), and b) with ischemic time over 3 hours (5 swine valves). The supravital staining of leaflet fragments was conducted with single solution of fluorescein diacetate (living cells staining) and propodium iodide (damaged cells staining). RESULTS: The simultaneous staining predominantly showed green fluorescence typical for living cells and few red damaged cells in the short ischemic time group, whereas the second group showed the predominance of the red stained damaged cells. CONCLUSIONS: The presented one-step supravital staining method is rapid and simple it allows differentiation of the viability of the valve cells, so it may be of value for the routine evaluation of cadaveric valve homografts.

Animals↗
PubMed2003

Choice of prosthetic heart valve for adult patients.

This review summarizes the major long-term (> or =10 to 15 years) patient outcomes after insertion of many Food and Drug Administration approved prosthetic heart valves (PHV). Mechanical PHV was associated with a better survival (p < 0.02) at 15 years after aortic valve replacement (AVR) than with a bioprosthesis in the Department of Veterans Affairs (DVA) trial. In both the DVA and the Edinburgh Heart Valve trials, bioprosthesis were associated with structural valve deterioration (SVD) (mitral valve replacement [MVR] > AVR) and, therefore, for replacement of the PHV. Thromboembolism and bleeding rate were higher with mechanical PHV. Mortality after AVR and MVR is high at 10 to 15 years because of the associated comorbid conditions and older age of patients. Outcomes with "new" good valves are similar to that with "older" good valves. Complication rates of thromboembolism, bleeding, endocarditis, and leak vary widely; the rates of these complications are not different among different mechanical PHV and among different bioprosthetic PHV. Structural valve deterioration is rare with mechanical PHV. Structural valve deterioration of bioprosthesis after MVR is higher than after AVR; after AVR, homografts and bioprosthesis have similar rates of SVD. The exact rate of SVD of the pulmonary autograft is uncertain. Valve prosthesis-patient mismatch is clinically important when it is severe and in selected patients when it is moderate. Bioprosthesis have a low rate of SVD in the older patient and, thus, are the PHV of choice for AVR in patients > or =60 to 65 years of age and for MVR in patients > or =65 to 70 years of age; in younger patients mechanical valves are the PHV of choice. In individual patients there may be exceptions to these general rules.

Adult↗
PubMed1985

Onset and progression of experimental bioprosthetic heart valve calcification.

Calcification, the major cause of bioprosthetic heart valve failures, is a serious clinical problem with uncertain pathogenesis. The objectives of the present study were to define the progressive chemical and morphologic sequence of mineralization in glutaraldehyde-treated porcine aortic valve cusps implanted subcutaneously in rats and to compare the pathology and pathophysiology of calcification in subcutaneous implants with that of orthotopic valve replacements in calves. Cusps were implanted subcutaneously in 3-week-old rats for 24 hours to 18 weeks. Cuspal calcium was 114 +/- 18 micrograms/mg of dry weight (mean +/- SEM) at day 21 and 218 +/- 6 at day 56 of implantation and unchanged thereafter. The earliest mineral deposits, noted at 48 hours, were associated with devitalized porcine connective tissue cells, but by 7 days, mineral deposits also involved collagen bundles. Scanning electron microscopy with energy-dispersive x-ray analysis demonstrated predominant accumulation in the spongiosa with a spongiosa to fibrosa energy-dispersive x-ray analysis count ratio of calcium of 15 at 21 days. In stent-mounted glutaraldehyde-preserved porcine valves implanted in five calves as mitral replacements for 69 to 142 days, cuspal calcium was 86 micrograms/mg (mean) (range 47 to 128). Calf implants also had cell oriented and collagen calcification predominating in the valvar spongiosa. In both rat subcutaneous and calf mitral valve models, early diffuse calcific microcrystals evolved into confluent nodules that disrupted tissue architecture. It is concluded that calcification of glutaraldehyde-preserved porcine aortic valves implanted subcutaneously in rats begins within 48 hours, earliest deposits are localized to residual porcine connective tissue cells, but latter deposits also involve collagen fibrils, mineralization is most prominent in the spongiosa, the pathology of calcification in rat subcutaneous implants and calf mitral replacements is comparable, suggesting a common pathophysiology, and calcific nodule formation most likely initiates clinical features.

Animals↗
PubMed2003

Carotid Doppler microembolic signals in patients one year after heart valve surgery.

Doppler ultrasound has been used to detect microemboli during and after cardiopulmonary bypass (CPB). The aim of the present study was to examine the frequency of microembolic signals (MES) in patients one year after heart valve replacement, to look for possible risk factors associated with MES and for any correlation with cerebral events. One hundred patients, 69 male and 31 female, mean age 66.3 +/- 12.4 years, were examined one year after heart valve replacement. Thirty patients, 61% male and 39% female, mean age 62.5 +/- 8.7 years, who had undergone cardiovascular operations without heart valve pathology served as controls. A newly developed microemboli detector, EMEX-25 (Hatteland Instrumentering, Norway) was used to detect MES from both carotid arteries. MES were detected in 61% of the valve patients. A correlation was found between the number of MES, previous cardiovascular operations, emergency surgery and EuroSCORE (p <0.05). There was no correlation between the number of MES and the level of anticoagulation expressed as international normalization ratio (INR), atrial fibrillation, serum-cholesterol, New York heart association (NYHA) class, gender, age, valve type or valve position. The average number of MES was not increased in seven patients who had experienced major (three) or minor (transient, four) cerebral events during follow-up. In the 30 nonvalve controls, MES were detected in 46% of the patients. MES were detected in valve patients as well as in nonvalve patients one year after surgery. In valve patients, a significant correlation was found between MES and previous surgery, emergency surgery and EuroSCORE. There was no correlation between the number of MES and INR level or postoperative cerebral events.

Aged↗
PubMed2006

Sex-dependence of the relative number of elastic fibres in human heart valves.

The aim of the current study was to find out whether there are sex-dependent differences in the relative number of elastic fibres in human heart valves. Twenty-six aortic valves, 26 mitral valves, 33 pulmonary valves and 28 tricuspid valves of both sexes were obtained at autopsy from newborn to 89-year-old patients who died of noncardiac diseases. The quantitatively morphometric investigations were carried out on conventionally stained (Resorcinfuchsin) histological sections. The results were qualitatively examined with immuno-histochemically marked (anti-elastin antibodies) histological sections. Earlier examinations by Leutert [1976. Z. Gesamte Inn. Med. 31, 97-104] showed that the atrioventricular valves have the following layers: endothelium, atrial fibroelastic tissue (S1), fibrous tissue, ventricular fibroelastic tissue (S2) and endothelium. In our study, the ventricular side of the semilunar valves corresponds to side S1, whereas the vessel side corresponds to side S2. Three regions of interest were examined on each side of the valves: base, mid and tip. The number of elastic fibres per measuring area for all four human heart valves was significantly higher (p < 0,001) in fibroelastic tissue of side S1 than in fibroelastic tissue of side S2. Neither on side S1 nor on side S2 were there significant gender-related differences in the relative number of elastic fibres per measuring area. The results suggest a characteristic distribution of the elastic fibre system which is not sex-dependent but closely related to the function of the heart valves.

Adolescent↗