Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “CARDIAC VALVES”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

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

At least 271 records · Page 15Linked to original sources
PubMed1992

[Determination of anaerobic threshold and influence of hemodynamics on exercise intolerance in patients after cardiac valve surgery].

In order to evaluate the exercise tolerance of the patients after cardiac valve surgery, the exercise stress test by supine bicycle ergometer was performed in 26 patients. An anaerobic threshold (AT) was determined by lactate threshold. The mixed venous oxygen saturation (SvO2) was measured simultaneously to assess the relationship between AT and SvO2 during exercise test. The study group consisted of 10 men (mean age: 46.2 years) and 16 women (mean age: 49.4 years). Each patient received either of following two programs: 1) a single step test of approximately 5 METS, which corresponded to the exercise tolerance level of NYHA functional Class II (Group A, 18 patients); and 2) a consecutive multi-staged test, which was begun at a worked of 25 W and increased by 25 W in every 3 minutes until the symptomatic maximum or ended at 100 W (Group B, 8 patients). Eleven patients (6 patients in Group A, 5 patients in Group B) had reached AT point during the test. SvO2 was 26.6 +/- 3.6% in group A patients, and 29.3 +/- 1.4% in group B patients at the point of AT. This data suggests that anaerobic metabolism begins at the level of SvO2 slightly less than 30%, and that SvO2 is a simple and usefull indicator for the estimation of AT. In patients with reduced exercise tolerance which was recognized by AT point at exercise stage of about 5 METS, the right atrial and pulmonary arterial mean pressure were higher than the others (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

A possible role for antiphospholipid antibodies in acquired cardiac valve deformity.

We studied the frequency of antiphospholipid antibodies (aPL) in patients undergoing cardiac valve replacement, and present the results in the context of the pathology of the valve lesions. Forty-eight consecutive patients undergoing valve replacement were studied. Of the whole group, 15 (31%) had antibody levels greater than 2 SD above the mean for a control group of healthy persons and 11 (23%) had a level of greater than 3 SD. There was an increased frequency of elevated antibody levels in patients with valves showing fibrocalcific change and a significant association between aPL and valve thrombus. The possible role of these antibodies in the pathogenesis of the valve lesions is discussed.

Aged↗
PubMed1987

The role of glutaraldehyde-induced cross-links in calcification of bovine pericardium used in cardiac valve bioprostheses.

Calcification is the principal cause of failure of tissue-derived cardiac valve replacements pretreated with glutaraldehyde (GLUT). The objective of this study was to determine the role of GLUT-induced cross-links in bovine pericardial tissue calcification. Various levels of 3H-GLUT incorporation were obtained by varying incubation pH, and protein modification was determined by amino acid analysis and resistance to collagenase digestion. Calcification of cross-linked tissue was studied using subdermal implants in rats. Low GLUT uptake (less than 150 nm/mg) resulted in minimal calcification (Ca2+, 12.8 micrograms/mg) and stability (4% residual weight following digestion) due to a limited crosslinking (lysine + hydroxylysine = 26.1 residues/1000 amino acids [AA]). In contrast, higher GLUT uptake induced more cross-links (Lys + Hyl = 8.2 residues/1000 AA) and consequent higher stability (95% residual wt); such tissues calcified severely (Ca2+, 93.5 micrograms/mg). Incorporation of GLUT two to three times beyond a critical level did not further enhance calcification. It is concluded that the amount of GLUT incorporated controls the extent of cross-links, which in turn directly determines tissue stability and calcification.

Aldehydes↗
PubMed1984

Cardiac valve prostheses in children without anticoagulation.

We have used the St. Jude Medical cardiac valve prosthesis without postoperative anticoagulation in 34 children undergoing valve replacement since March, 1979. The 19 boys and 15 girls ranged in age from 9 months to 21 years. The valve replaced was mitral in 12 patients, aortic in 14, pulmonary in three, and both mitral and aortic in two. One patient had implantation of a St. Jude Medical valve in a pulmonary conduit, and a left-sided tricuspid valve was replaced in two children. There were three operative deaths, all in infants with complex disease. One patient died suddenly at home 5 weeks after valve replacement, probably of ventricular arrhythmia. During follow-up of 1 to 50 months, comprising 646 patient months, no thromboembolic complications have been observed. Although use of the St. Jude Medical prosthesis without anticoagulation is still investigational, our preliminary data suggest that the risk of thromboembolism in unanticoagulated children with this valve is not greater than that in anticoagulated adults. The results justify continuing investigation of the St. Jude Medical prosthesis in children without postoperative anticoagulation.

Adolescent↗
PubMed1981

[Pregnancy and delivery following cardiac valve replacement (author's transl)].

We describe 30 patients with Starr-Edwards cardiac valve replacements who underwent pregnancy. Fourteen pregnant women who received anticoagulants gave rise to 3 neonatal anomalies such as congenital heart disease, polydactylia and microphthalmus. And fetal losses were 5 spontaneous abortions. Women with artificial valves can tolerate the hemodynamic load of pregnancy well, but there is an increased fetal wastage in patients taking oral anticoagulants (coumarin: warfarin). Namely, there is probably largely attributable to fetal hemorrhage but there is also a risk of malformation caused by teratogenic effects of warfarin. In contrast, pregnant women who didn't receive anticoagulants had the risk of thrombo-embolismus. It is suggested that the best plan is to use long acting oral anticoagulants during antenatal period and heparin over the periods of labor.

Abortion, Induced↗
PubMed1978

The determinants of survival following reoperation on prosthetic cardiac valves.

In an effort to identify the determinants of survival following reoperation on patients with prosthetic cardiac valves, the experience with a group of 33 patients at the University of Rochester Medical Center was reviewed. The survival rate was 58% (19/33). Survival was not related to the valve involved, the age of the patient, or the technical hazards of a second cardiac operation. Ten (77%) of the 13 patients in New York Heart Association (NYHA) Functional Class II survived compared with 8 (40%) of the 20 in Class III or IV. The survival rate for patients with a paravalvular fistula was 79% (11/14); with valve dysfunction, 50% (6/12); and with prosthetic valve infection, 29% (2/7). The determinants of survival seem to be similar to those for primary operation (i. e., NYHA patient classification and indication for operation) and less related to the potential operative complications of a reoperation.

Age Factors↗
PubMed1998

Role of the NF-ATc transcription factor in morphogenesis of cardiac valves and septum.

In lymphocytes, the expression of early immune response genes is regulated by NF-AT transcription factors which translocate to the nucleus after dephosphorylation by the Ca2+-dependent phosphatase, calcineurin. We report here that mice bearing a disruption in the NF-ATc gene fail to develop normal cardiac valves and septa and die of circulatory failure before day 14.5 of development. NF-ATc is first expressed in the heart at day 7.5, and is restricted to the endocardium, a specialized endothelium that gives rise to the valves and septum. Within the endocardium, specific inductive events appear to activate NF-ATc: it is localized to the nucleus only in endocardial cells that are adjacent to the interface with the cardiac jelly and myocardium, which are thought to give the inductive stimulus to the valve primordia. Treatment of wild-type embryos with FK506, a specific calcineurin inhibitor, prevents nuclear localization of NF-ATc. These data indicate that the Ca2+/calcineurin/NF-ATc signalling pathway is essential for normal cardiac valve and septum morphogenesis; hence, NF-ATc and its regulatory pathways are candidates for genetic defects underlying congenital human heart disease.

Animals↗
PubMed1992

Experimental in vitro endothelialization of cardiac valve leaflets.

This study reports our results with vitro endothelialization of fresh nonpreserved homograft valve leaflets compared with mild alternatively preserved valves and valves treated by preservation procedures commonly used for commercially available tissue valves. In vitro lining of biological heart valves with cultured autologous endothelial cells might help prevent the detrimental effects of degeneration on valve durability. To investigate the growth characteristics of endothelial cells on valve bioprostheses, three different methods of storage and preservation were compared. After precoating with fibronectin and seeding of 4.4 x 10(4) endothelial cells/cm2 onto the different leaflet surfaces, primary adherence, growth kinetics, morphology, and maintenance of monolayer integrity were studied over a period of 10 days. On valve leaflet surfaces of group 1 (fresh nonpreserved homograft valve leaflets) and group 2 (mild alternatively preserved valves), endothelial cells grew to persistent monolayers between days 6 and 10. In contrast, endothelial cell proliferation with monolayer growth could not be achieved on the group 3 leaflets (preserved like commercially available biological valve prostheses). In that group, no viable endothelial cells could be found on the valve surfaces 2 days after seeding. These results demonstrate the theoretical feasibility of endothelializing biological heart valve leaflets in vitro if they are not preserved and stored according to commonly used procedures. Provided such an endothelium can withstand the mechanical forces after implantation in vivo, in vitro endothelialization might contribute either to the development of new biological heart valves for modern cardiac surgery or to the improvement of clinical results with homograft valve transplants.

Bioprosthesis↗
PubMed1995

The autologous tissue cardiac valve: a new paradigm for heart valve replacement.

This is a report of early clinical experience with an autologous tissue cardiac valve, which demonstrates the feasibility of making a bioprosthesis in the operating room in 10 minutes at the time of the valve replacement operation. There were 30 implant patients (18 men, 12 women), with ages ranging from 32 to 83 years. Diagnoses included calcified aortic stenosis (n = 16), pure aortic insufficiency (n = 9), and mixed aortic stenosis and insufficiency (n = 5). Associated diagnoses have included chronic renal failure treated with dialysis (n = 1), coronary artery disease requiring concomitant coronary bypass (n = 1), ascending aortic aneurysm requiring resection (n = 3), and mitral insufficiency requiring concomitant mitral valvuloplasty (n = 2). All of the valve replacements were in the aortic position. These implanted patients are being followed up carefully according to the protocol that requires examination every 6 months for the first year and every 12 months subsequently. No patient has been lost to follow-up. Twenty-seven patients are alive and well from 1 to 22 months postoperatively. There were three deaths: two perioperative deaths (one perivalvular leak and one hemorrhage) and one infective endocarditis 1.3 years after valve replacement. All surviving patients were followed up by echocardiographic examination (mean gradient, 15.5 +/- 6.8 mm Hg at 1 year). In conclusion, the feasibility of this method and concept has been demonstrated with implants in 30 patients. The validity of the technique will be judged by clinical results and experiences in children.

Adult↗
PubMed1977

Cardiac valve prostheses, anticoagulation, and pregnancy.

A series is presented of 7 women who underwent cardiac valve replacement and who ultimately became pregnant. The only infant death was that of a premature baby whose mother received oral anticoagulants until delivery. The remaining 6 babies were normal and survived. One mother died suddenly on the fourth postpartum day and was found to have a periprosthetic clot on postmortem examination. Although a certain risk exists for the fetus whose mother receives oral anticoagulants since they cross the placental barrier, this risk is far lower that that for the mother who does not receive anticoagulation. From a prospective point of view, it would appear preferable to use prostheses such as the porcine heterograft that do not necessitate the administration of anticoagulants.

Adolescent↗
PubMed1986

Metallurgical analysis of failed Björk-Shiley cardiac valve prostheses.

An investigation into the mechanisms of failure of current Björk-Shiley cardiac valve prostheses is reported. Two failed valves, one apparently unfailed but defective valve, and one unused valve, were examined by scanning electron microscopy and metallographic section. In the first two valves (removed 12 and 23 months after implantation) fracture was associated with the welds joining the short strut to the valve ring. The fracture surfaces in all cases were heavily faceted and showed branching cracks. Extensive wear had occurred on one fracture surface in the first case, suggesting that one leg of the short strut had failed before the other, though this had been clinically undetectable. The third valve was removed owing to failure of the suturing (24 months after implantation) but one leg of the short strut was found to be completely fractured. The other leg showed extensive cracking and porosity in the weld region. A metallographic section taken through the weld region of the fourth (unused) valve illustrated several sizable defects directly attributable to the welding process. It is suggested that the valves failed by fatigue and that these problems could be overcome if the complete valve cage were machined as a single piece.

Aged↗
PubMed1975

Pregnancy after the insertion of three cardiac valve prostheses.

A successful pregnancy occurring in a woman after the insertion of three cardiac valve prostheses, viz. aortic, mitral and tricuspid, is described. It appears that pregnancy in such circumstances is not an unacceptable hazard for the woman. Oral anticoagulant drugs increase the perinatal morbidity and mortality.

Adult↗
PubMedDate not supplied

[Detection of bacterial molecular markers in the tissue of cardiac valves in normal and pathological states by gas chromatography and mass spectrometry].

Samples from cardiac valves of 31 patients were analyzed by gas chromatography and mass spectrometry. The algorithm of mass spectrometric parameters was developed, which permitted the determination of about 200 known microbial fatty acids, aldehydes and sterols, sufficient for the detection and quantitative determination of more that 170 taxons of clinically significant microorganisms on the genus or species levels. The quantitative and qualitative differences in the composition of microbial markers of endocardial valves in normal and pathological states, particularly in cases of infectious endocarditis, were detected. The participation of 37 microbial taxons in the process was confirmed. The level of endocardium colonization in infectious endocarditis reached from 2 to 7 x 10(9) microbial cells/g of valvular tissue (which exceeded twofold the equivalent concentrations of the marker in the normal state). In terms of quantity, the leading role was played by Cardiobacterium hominis.

Adolescent↗
PubMed1992

Patients with prosthetic cardiac valves followed in southern Thailand.

Prospective follow-up of 174 post-prosthetic cardiac valves have been done at Prince of Songkla University and Hat Yai Regional hospitals since 1985. The total follow-up time was 549 patient-years (pt-yr). Thirty per cent had been followed for 1 year or less. Eighty-two per cent of the patients had their mitral valves replaced either singly or as part of a multiple replacement. Thirty per cent of the time, the prothrombin time was below therapeutic range. Major events did not appear to be different from other reports: 2.7 embolic events per 100 pt-yr, 3.2 major bleeds and 3.2 deaths which may eventually be as high as 4.4 if a portion of the lost patients was assumed to have died. Events related to prosthetic valves and anticoagulation seemed to occur predominantly 1-2 years after surgery.

Adolescent↗
PubMed1987

Evaluation of explanted polyurethane trileaflet cardiac valve prostheses.

Morphologic, chemical, and hemodynamic studies were made of eight prototype polyurethane trileaflet cardiac valve prostheses that had been implanted in juvenile sheep for 17 to 21 weeks in the mitral position. Calcification of the polyurethane leaflet surfaces was the principal finding. Quantitative chemical analyses revealed calcium values with a mean of 42.7 +/- 21 mg/gm dry weight of leaflet. Morphologically, two distinct types of calcification were observed: One was associated with the polyurethane surface or the interface between the leaflet surface and microthrombi or fibrous sheaths; the other was characterized by calcification associated with degenerated cells within thrombotic material and the fibrous sheath. These morphologic findings were in accord with the results of hemodynamic performance studies indicating that these heart valve prostheses had become both stenotic and regurgitant.

Animals↗
PubMedDate not supplied

Cardiac valve replacement: Canadian review 1978-86.

The total number of cardiac patients requiring valve surgery in Canada has remained relatively constant over the years 1978-86, at about 2900 cases per year. However, the type of valve used has changed with most centres now using bioprosthetic valves as compared to mechanical valves which were popular until 1978. Unfortunately, there is a lack of uniform follow-up data on cardiac valve replacement patients and a countrywide registry is needed in order to monitor morbidity, mortality and long term results.

Aortic Valve↗
PubMed1967

Current status of prosthetic cardiac valves.

The majority of patients with acquired valvular heart disease have severe damage to valves which is not amenable to repair but can now be treated by valve replacement with an acceptable mortality and morbidity. The caged ball or disc valve is widely used and is proving clinically satisfactory for cardiac valve replacement. Thromboembolism is the significant complication. With improvement in technique the incidence of infection, detachment and other complications has been reduced.

Heart Valve Diseases↗
PubMed1980

[Use of biological prostheses for cardiac valve replacement in children and adolescents].

Between January 1976 and June 1980 a consecutive series of 13 patients aging from 9 to 18 years underwent cardiac valve replacement, out of 590 valve replacement operations. All had rheumatic heart disease and many had severe cardiac symptoms; all underwent cardiac catheterization and angiography before operation. Ten single valve replacements, 7 in the aortic, and 3 in the mitral position, and 3 double valve replacements were performed. All patients survived operation, except the one who died 2 months later for congestive heart failure. The others have been followed from 1 to 47 months, averaging 20,5 months. All are free of cardiac symptoms and are being treated with antirheumatic drugs. They are not anticoagulated after 6 months. The operative mortality is low in our bioprosthetic valve replacement, and we think that these operations are safely feasible.

Adolescent↗