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At least 919 records · Page 51Linked to original sources
PubMed1999

The new St. Jude Medical regent mechanical heart valve: laboratory measurements of hydrodynamic performance.

BACKGROUND AND AIM OF THE STUDY: The St. Jude Medical (SJM) mechanical heart valve was the first bileaflet valve with leaflets and orifice all fabricated from pyrolytic carbon. In 1992, a supra-annular cuff configuration, the SJM mechanical heart valve Hemodynamic Plus Series (HP), was introduced, which gave a one-size gain in orifice area over the standard valve. In a continuing effort to improve hydrodynamic performance, a new enhanced configuration of the mechanical valve - the SJM Regent valve - has been developed. The blood-contacting components of the SJM Regent valve have the same design features as those of the standard or HP valve, but the orifice lumen area has been increased, without compromising structural integrity, by a shift in the cuff-retaining orifice rims. METHODS: Valve performance has been measured using a laboratory simulation of the left heart system. Three samples of both valve types (SJM Regent, HP) for sizes 17 mm to 27 mm, were tested at a cardiac output of 5 l/min. Supplementary steady-flow measurements were made at flow rates between 5 and 30 l/min. Pressure and flow signals were recorded and several performance parameters, including pressure gradient, effective orifice area (EOA), insufficiency (regurgitant volume as a percent of forward flow volume) and energy loss, were computed. RESULTS: All sizes of the SJM Regent valve showed improved hydrodynamic performance compared with the HP valve. For the small sizes (17, 19, 21 mm), the pressure gradient of the SJM Regent decreased by 37%, 36% and 39%, respectively; the EOA increased by 22%, 22% and 21%; and the total transaortic energy loss decreased by 33%, 31% and 31% compared with the HP valve. The regurgitation for both valves ranged between 4% and 8% of forward flow volume over the 17-27 mm size range. CONCLUSIONS: Hydrodynamic measurements confirm the gain of the SJM Regent valve over the HP valve that is expected based on the increased geometric orifice area. Given its basic similarity of design, but with an increased EOA as demonstrated in vitro, the SJM Regent valve is anticipated to provide an increased level of clinical benefit.

Biocompatible Materials↗
PubMed2005

Does EuroSCORE predict length of stay and specific postoperative complications after heart valve surgery?

BACKGROUND AND AIM OF THE STUDY: EuroSCORE is the most rigorously evaluated scoring system in cardiac surgery. The study aim was to evaluate the performance of EuroSCORE in the prediction of in-hospital postoperative length of stay and specific major postoperative complications after heart valve surgery. METHODS: Data obtained from 1,105 consecutive patients who underwent isolated or combined heart valve surgery were collected prospectively. The EuroSCORE model (standard and logistic) was used to predict in-hospital mortality, prolonged length of stay (> 20 days) and major postoperative complications. A C statistic (receiver operating characteristic curve) was used to test discrimination of the EuroSCORE. Calibration of the model was assessed by the Hosmer-Lemeshow goodness-of-fit statistic. RESULTS: In-hospital mortality was 6.3%, and 21.7% of patients had one or more major complication. EuroSCORE showed very good discriminatory ability in predicting postoperative renal failure (C statistic: 0.78) and good discriminatory ability in predicting in-hospital mortality (C statistic: 0.72), prolonged length of stay (C statistic: 0.71), stroke over 24 h (C statistic: 0.73), gastrointestinal complications (C statistic: 0.73) and respiratory failure (C statistic: 0.71). There were no differences in terms of the discriminatory ability between standard and logistic EuroSCORE. The standard EuroSCORE model showed good calibration in predicting these outcomes (Hosmer-Lemeshow: p > 0.05). The logistic EuroSCORE model showed good calibration, except for prolonged length of stay and respiratory failure. CONCLUSION: EuroSCORE can be used to predict not only in-hospital mortality, for which it was originally designed, but also prolonged length of stay and specific postoperative complications such as renal failure, stroke over 24 h, gastrointestinal complications and respiratory failure within the whole context of heart valve surgery. These outcomes can be predicted accurately using the standard EuroSCORE, which is very easily calculated.

Aged↗
PubMed2004

Localized gene delivery using antibody tethered adenovirus from polyurethane heart valve cusps and intra-aortic implants.

The present study investigated a novel approach for gene therapy of heart valve disease and vascular disorders. We formulated and characterized implantable polyurethane films that could also function as gene delivery systems through the surface attachment of replication defective adenoviruses using an anti-adenovirus antibody tethering mechanism. Our hypothesis was that we could achieve site-specific gene delivery to cells interacting with these polyurethane implants, and thereby demonstrate the potential for intravascular devices that could also function as gene delivery platforms for therapeutic vectors. Previous research by our group has demonstrated that polyurethane elastomers can be derivatized post-polymerization through a series of chemical reactions activating the hard segment amide groups with alkyl bromine residues, which can enable a wide variety of subsequent chemical modifications. Furthermore, prior research by our group investigating gene delivery intravascular stents has shown that collagen-coated balloon expandable stents can be configured with anti-adenovirus antibodies via thiol-based chemistry, and can then tether adenoviral vectors at doses that lead to high levels of localized arterial neointima expression, but with virtually no distal spread of vector. Thus, we sought to create two-device configurations for our investigations building on this previous research. (1) Polyurethane films coated with Type I collagen were thiol activated to permit covalent attachment of anti-adenovirus antibodies to enable gene delivery via vector tethering. (2) We also formulated polyurethane films with direct covalent attachment of anti-adenovirus antibodies to polyurethane hard segments derivatized with alkyl-thiol groups, thereby also enabling tethering of replication-defective adenoviruses. Both formulations demonstrated highly localized and efficient transduction in cell culture studies with rat arterial smooth muscle cells. In vivo experiments with collagen-coated polyurethane films investigated an abdominal aorta implant model in pigs using a button configuration that simulated the blood contacting environment of a vascular graft. One week explants of the collagen-coated polyurethane films demonstrated 14.3+/-2.5% of neointimal cells on the surface of the implant transduced with green fluorescent protein - adenovirus (AdGFP) vector loadings of 1 x 10(8) PFU. PCR studies demonstrated no detectable vector DNA in blood or distal organs. Similarly, polyurethane films with direct attachment of antivector antibodies to the surface were used in sheep pulmonary valve leaflet replacement studies, simulating the blood contacting environment of a prosthetic heart valve cusp. Polyurethane films with antibody tethered AdGFP vector (10(8) PFU) demonstrated 25.1+/-5.7% of attached cells transduced in these 1 week studies, with no detectable vector DNA in blood or distal organs. In vivo GFP expression was confirmed with immunohistochemistry. It is concluded that site-specific intravascular delivery of adenoviral vectors for gene therapy can be achieved with polyurethane implants utilizing the antivector antibody tethering mechanism.

Adenoviridae↗
PubMed1993

Endothelialization of mechanical heart valves in vitro with cultured adult human cells.

Previous studies have shown that in vitro endothelialization of synthetic vascular prostheses with cultured autologous cells leads to a reduction in their thrombogenicity. It is possible that pre-endothelialization of mechanical heart valve prostheses would have a similarly advantageous effect. In this study we have therefore investigated the possibility of creating an endothelium layer on mechanical heart valve prostheses by seeding in vitro with cultured adult human endothelial cells. After harvest, endothelial cells were cultured for two to three weeks before seeding of six valves (three Monostrut, three CarboMedics bileaflet) with 1.5-2 x 10(5) cells/cm2. The valves were then kept under culture conditions for seven days. A confluent lining of cultured endothelial cells was observed in the scanning electron microscope on the parts covered with pyrolitic carbon, e.g. disc, leaflet, flange, and on carbon coated sewing rings. Untreated sewing rings showed a discontinuous endothelial lining. On the metallic surface only a few scattered cells were observed. Two endothelialized bileaflet valves were implanted in the mitral position in pig and permitted to perform physiologic work for one hour. A mainly continuous endothelium remained on the carbon covered sewing rings but the endothelium detached from the leaflets and flanges. This study demonstrates that mechanical heart valves do not contain cytotoxic compounds. It also demonstrates that cultured adult human endothelial cells are able to form a monolayer when seeded on monostrut and bileaflet valve prostheses. A significant number of cells remain on the sewing ring after pulsatile flow in the mitral position but not on the polished pyrolitic carbon surfaces.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell Adhesion↗
PubMed2005

Residual antibiotics in allograft heart valve tissue samples following antibiotic disinfection.

Antibiotics are routinely used for the decontamination of allograft heart valves. To monitor the efficacy of this process, samples of tissue are sent for microbiological analysis. This investigation was undertaken to determine residual antibiotic concentrations in decontaminated tissue and to assess the likely inhibitory effect on microbiological cultures. After a typical decontamination protocol, both gentamicin and vancomycin were present in all tissue samples and the majority of enrichment broths at concentrations sufficient to inhibit most bacteria. The data presented indicate that protocols used by heart valve banks and associated microbiology laboratories should be reviewed, and support the use of predecontamination cultures to identify particularly virulent micro-organisms.

Animals↗
PubMed1992

A study of the stability of orientation in the CarboMedics bileaflet heart valve prosthesis.

A total of 25 CarboMedics bileaflet prostheses was studied in the immediate postoperative period and at 1 week, 1 month and 3 months after surgery. No evidence of rotation was found on visual comparison of valve orientation and there were no significant differences between successive studies for the distance between the septum and either the anterior (P = 0.92) or posterior leaflet (P = 1.00) of valves in the mitral position. The possibility of spontaneous rotation is a potential drawback not only of the CarboMedics prosthesis, but also of designs currently being developed. This study suggests that major rotation does not occur commonly.

Adult↗
PubMed1993

Heart valve surgery.

Progress in valve repair and replacement continued over the past year. Aortic valve repair for aortic insufficiency appears promising, and aortic decalcification may still be a useful alternative in certain cases of aortic stenosis. Mitral valve repair, well accepted for myxomatous valves, presents a challenge in ischemic disease. Balloon mitral valvotomy offers significant short-term hemodynamic improvement, but needs to be properly compared with surgical treatment of mitral stenosis. Although aortic valve replacement with homografts and pulmonary autografts yields excellent results, enthusiasm for the stentless porcine xenograft is increasing. Clinical results reported for the Carpentier-Edwards pericardial valve (Baxter Healthcare Corp., Edwards Div., Santa Ana, CA) and the Bjork-Shiley monostrut valve (Shiley Inc., Irvine, CA) are excellent. Acute endocarditis continues to be a challenging problem but early aggressive debridement appears to offer patients the best chance of cure, regardless of what valve replacement is used.

Aortic Valve↗
PubMed1975

[Echography in heart valve diseases].

The authors discuss the value of echorcardiography in cardiac valvular disease. Exploration of the mitral valve gives very precise data concerning diagnosis and evaluation of the degree of mitral stenosis. It may be of value in the diagnosis of certain complications such as intra-atrial thrombosis and gives reliable information in postoperative surveillance. In mitral insufficiency, echocardiography sometimes permits the recognition of certain mechanisms such as rupture of the cordae, ballooning of the lesser cusp and abnormal kinetics in obstructive cardiomyopathy. Exploration of the aortic valve is less informative. Aortic insufficiency gives scarcely any direct signs, whilst echocardiography is of value in aortic stenosis. Ultrasonic study also is useful in surveillance of the kinetics of valvular prostheses. The total absence of risk makes repeated studies possible, rendering echocardiography an essential element in the study of valvular disease.

Aortic Valve Insufficiency↗
PubMed2004

[Thrombosed mechanical heart valve prostheses].

Our clinical experiences of treatment for definite or probable thrombosed mechanical valve prostheses was presented and discussed concerning with surgical indication, several operative approaches to a target valve and detail surgical techniques. Preoperative diagnosis includes loss of metallic click sound, abnormal restricted disc movement and echocardiographic evidences of annular, occluder or housing thrombus. Valve re-replacement or thrombus removal was performed with re-do sternotomy or thoracotomy in urgent or elective cardiopulmonary bypass. Careful preparation of right atrium, superior and inferior vena cava and ascending aorta, and establishment of moderate hypothermic cardiopulmonary bypass were essential for re-replacement of the thrombosed valve. Among 15 patients, mitral re-replacement was performed in 10, aortic re-replacement in 3, tricuspid re-replacement in 2 and thrombus removal in 1. Hospital mortality rate was 6.7%, and late recurrence of thrombosed valve was observed in a patient. Pathophysiology of thrombotic process and bioactivity on the prosthetic valves are yet unsolved. Further refinement of clinical strategy would be necessary in relation to the effect of antithrombotic and antiinflammatory treatment.

Aortic Valve↗
PubMed1990

[Current status of heart valve surgery].

Surgical techniques for the repair of defect pulmonary, tricuspid, mitral and aortic valves are described. Valvuloplasty as well as replacement of valves by mechanical and biological mechanisms are outlined and the results discussed.

Aortic Valve↗
PubMed1989

[Study of the late results of reimplantation of heart valve prostheses based on 15-year experience].

Authors studied two groups of patients, in which a cardiac valvular prosthesis was reimplanted within 15 years. Data of patients reoperated on (group A) were used to estimate indications, surgical methods, postoperative course and late results. Data of patients which underwent surgery and then requiring reoperation (group B) were used to evaluate the percentage of reoperation falling to 1 patient/1 year according to a primary implanted valvular prosthesis: 42 patients were divided into two groups. 3 perioperative and 12 late deaths (totally 28.3%) were stated in the group A. 5- and 10-year survival rates were 83.3% and 65.6%, respectively. In the group B the lowest percentage of reoperation (1 patient/1 year) were stated in patients with mitral Starr-Edwards 6120 valve (029) and Björk-Shiley aortic valve (0.13). The highest percentage of reoperation was observed in patients with biological prosthetic valves (homograft or heterograft--4.64) and in comparison with patients with primary implanted mechanical prostheses (0.24). Those differences were statistically significant (p less than 0.001).

Adult↗