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At least 19 recordsLinked to original sources
PubMed1975

Age-dependent changes of heart valves and heart size.

The mode and extent of the regressions of heart valves, valvular rings, and tendon chords, as well as the size of atria and ventricles in 316 hearts of different age groups (macroscopically normal at autopsy), were studied. With increasing age, the valves showed marked thickening and loss of elasticity. Deposition of lipoids and calcification occur to a variable extent in the valvular tissue and rings; Valve size shows a change of minor degree, but tendon chords and papillary muscles shorten in old age. The diameters of the atria, mitral, tricuspid, pulmonary, and aortic rings increase continuously up to the 9th decade of life. The width and length of the ventricles show minor alterations in size. In old age, heart weight increases.

Adolescent↗
PubMed1975

[Heart valves in rheumatic heart disease in the light of scanning electron microscopy].

In case of rheumatic sclerosis the micro-relief of the surface of the mitral and aortic valves changes considerably: the first order plicas disappear, a new chaotic micro-relief is formed that depends on the deep specific changes in the collagen-elastic structures of the valves. In rheumatic heart diseases the valves are characterized by focal disendothelization of the surface, which permits to examine the valve in layers, and to study not only its surface, but also its internal subendothelial structures. Scanning electron microscopy permitted to visualize for the first time in a full three-dimentional image the severely altered collagen structures of the disendothelialized portions of rhumatic valves. The changes in the micro-telief consisting in the appearance of amall, irregularly located plicas, crossing each other under various angles, are caused by the development of new subendothelial collagen fibers. The initial forms of calcification are characterized by the appearance of micro-plates of calcination in the zones of the destroyed micro-relief, the subsequent forms -- by the formation of large clusters of calcination due to the fusion of the micro-plates. The destroyed micro-relief of the valves causes the adhesion of erythrocytes on their surfaces, which may be considered a factor halping thrombus formation.

Adult↗
PubMedDate not supplied

Experience with tissue heart valves.

Experience with tissue valves for heart valve replacement over the past seven years is presented and analyzed. Between February 1967 and March 1969, 87 patients had heart valves replaced with preserved heterologous aortic valves. Valve failure occurred in 19 of the 70 operative survivors. There are 45 long-term survivors with heterologous aortic valves; 10 have regurgitant murmurs and 35 have valves functioning normally. Microscopic examination of failed valves has shown that the heterologous aortic valve gradually becomes a mechanically vulnerable structure in a state of rejection. During the past five years. autologous and homologous fascia lata and heterologous pericardium, mounted on a support frame, were used in 241 patients (131 aortic, 103 mitral and seven tricuspid). The follow-up period for the fascia lata group was 40 to 62 months and for the pericardial group 7 to 39 months. There have been significant differences in valve function with regard to both the site of valve insertion and the type of tissue used. Pericardial valves in the aortic position have produced the best results and autologous fascial valves in the mitral position, the worst. Valve failure occurred in only six patients, all with autologous fascia in the mitral position. The incidence of thromboembolism in the entire series was very low even though anticoagulants were not used. Analysis of clinical and hemodynamic results has shown that preserved heterologous pericardium has the potential for an adequate heart valve substitute.

Adolescent↗
PubMed1978

Tissue valve replacement of prosthetic heart valves for thromboembolism.

Twenty-five patients who had repeated thromboemboli from a prosthetic mitral valve were treated with reoperation using a tissue valve prosthesis. Reoperation was performed an average of 4.0 years after the original valve replacement in 14 men and 11 women, with an average age of 50 (range 35 to 65) years. A stented allograft was used in the first 7 patients and a porcine xenograft in the last 18 patients. There were one hospital death and two late deaths. With the first prosthetic valve there were 66 documented embolic episodes in 101.5 patient years (0.65 embolus/year). Only four embolic episodes in 67.4 patient years (0.059 embolus/year) occurred after tissue valve replacement (P less than 0.001). These results indicate that in patients with recurrent or severe embolization after prosthetic heart valve replacement, rereplacement with a tissue prosthesis can be safely performed and significantly reduces the likelihood that additional embolic episodes will occur.

Adult↗
PubMed1979

Current heart valve prostheses.

Current heart valve prostheses may be classified as either mechanical or tissue valves (bioprostheses). The principal advantage of mechanical devices is their established long-term durability; however, chronic anticoagulation is recommended to reduce the incidence of thromboembolic complications. Tissue valves are associated with a relatively low rate of thromboembolism but their durability level has not been determined. All contemporary prosthetic heart valves yield comparable survival rates.

Aortic Valve↗
PubMed1975

Diagnosis and management of complications of prosthetic heart valves.

Complications after heart valve replacement remain a substantial source of morbidity and mortality despite continuing advances in surgical care and prosthetic design. Infectious endocarditis occurs in about 4 percent of patients and may appear early (within 60 days) or late after operation. Endocarditis of early onset is commonly due to staphylococcal, fungal or gram-negative organisms and is fatal in 70 percent or more of cases. Infection of late onset is more often of streptococcal origin and the mortality rate is lower, about 35 percent. With either type, prompt recognition, vigorous and appropriate antimicrobial therapy and early consideration of surgical intervention are crucial. The postperfusion and postpericardiotomy syndromes are relatively common and relatively benign syndromes associated with postoperative fever. Their recognition is important to prevent confusion with endocarditis or sepsis and thus to reassure the patient and physician. Treatment is primarily symptomatic. Intravascular hemolysis occurs with most prosthetic heart valves but is more common with certain prostheses and with paraprosthetic valve regurgitation, with significant hemolytic anemia in 5 to 15 percent. Oral iron replacement therapy is effective in the majority of patients, but occasionally blood transfusion or reoperation for leak around the prosthesis is necessary. Prosthesis dysfunction due to thrombus may be recognized clinically by recurrence of heart failure, syncope, cardiomegaly and altered prosthetic valve sounds or new murmurs. Hemodynamic studies verify the diagnosis, and prompt reoperation is indicated for this potentially lethal problem. Systemic embolization has decreased markedly with the introduction of cloth-covered prostheses and is frequently related to erratic or ineffective anticoagulant therapy. We continue to recommend anticoagulant therapy for all patients with prosthetic heart valves unless there is a major contraindication.

Anemia, Hemolytic↗
PubMed1992

[Mineralization of heart valves].

Mineralization (calcification) of heart valves (mitral, aortic and aortic bioprosthesis) have been analyzed using; histology, x-ray diffraction, infrared spectroscopy, scanning microscopy, atomic absorption and electron microprobe. Obtained results showed the presence of two type of mineralization. First type is represented by grains composed of hydroxyapatite containing admixture of carbonates. This mineralization is seen macroscopically. Second type of mineralization is possible to determine only using chemical methods. It is represented by biological structures containing amount of Ca, P and other elements higher then normal heart valves. This second type of the mineralization conducts to the changes of physical features of the tissue. Both types of calcification develops because of the defects of atomic structure of biological components of heart valves (mainly collagen). These defects show the presence of free atomic bindings i.e. electric potential. Because of this, they are able to react with surrounding free joints, starting calcification. Defects of biological structures of heart valves are the results of infections, mechanical destruction of the valves etc. Calcification may be stopped on different stages of its development: or as secret calcification or may pass to the stage seen as apatite grains.

Adult↗
PubMed1978

Characterization of pepsin-solubilized bovine heart-valve collagen.

Collagens extracted from heart valves by using limited pepsin digestion were fractionated by differential salt precipitation. Collagen types were identified by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis, amino acid analysis and cleavage with CNBr. Heart-valve collagen was heterogeneous in nature, consisting of a mixture of type-I and type-III collagens. The identity of type-III collagen was established on the basis of (a) insolubility in 1.7 M-NaC1 at neutral pH, (b) behaviour of this collagen fraction on gel electrophoresis under reducing and non-reducing conditions, (c) amino acid analysis showing a hydroxyproline/proline ratio greater than 1, and (d) profile of CNBr peptides on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis showing a peak characteristic for type-III collagen containing peptides alpha1(III)CB8 and alpha1(III)CB3. In addition to types-I and -III collagen, a collagen polypeptide not previously described in heart valves was identified. This polypeptide represented approx. 30% of the collagen fraction precipitated at 4.0 M-NaCl, it migrated between beta- and alpha1-collagen chains on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis and its electrophoretic behaviour was not affected by disulphide-bond reduction. All collagen fractions from the heart valves contained increased amounts of hydroxylysine when compared with type-I and -III collagens from other tissues. The presence of beta- and gamma-chains and higher aggregates in pepsin-solubilized collagen indicated that these collagens were highly cross-linked and suggested that some of these cross-links involved the triple-helical regions of the molecule. It is likely that the higher hydroxylysine content of heart-valve collagen is responsible for the high degree of intermolecular cross-linking and may be the result of an adaptive mechanism for the specialized function of these tissues.

Amino Acids↗
PubMedDate not supplied

Support of cardiac performance following heart valve surgery by raising heart rate to the optimal pacing rate.

Effects of hemodynamic parameters of heart rate were studied in 19 patients with low cardiac output syndrome following open heart surgery for mitral and/or aortic valve replacement in the first five postoperative days. The central venous pressure (CVP), left atrial mean pressure (LAMP), and arterial blood pressures were determined at spontaneous heart rate (SHR), and during graded atrial (12 pts.) or ventricular (7 pts.) pacing each day. An "optimal pacing rate" (OPR), characterized by the most advantageous arterial pressures at the possible lowest levels of CVP and LAMP, and by the suppression of preexisting arrhythmias, if any, was established daily for maintaining each patient on that rate. The SHR was 69 +/- 9 and the OPR was 102 +/- 9 on the first postoperative day. For the fifth postoperative day the SHR was 68 +/- 10 and the OPR decreased to 90 +/- 9. Pacing with the OPR significantly increased cardiac performance. E.g. the hemodynamic improvement on the first postoperative day induced by pacing was comparable to the spontaneous improvement seen during the first five postoperative days. The hemodynamic effect of atrial pacing on circulation was more definitive than that of ventricular pacing. Since OPR may be significantly higher than SHR and varies from day to day, we suggest that, in cases where pacing is applied to improve cardiac performance, it be determined for each patient individually each postoperative day.

Adolescent↗
PubMed1977

[Heart valve prosthesis in congenital heart defects].

The experience of 68 cases of prosthetic valve replacement for congenital heart diseases is presented. The majority of the cases were 57 patients with the Ebstein anomaly and tetralogy of Fallot. In the patients with the Ebstein anomaly the tricuspid valve was replaced, in those with the tetralogy of Fallot--a plastic enlargement of the pulmonary artery trunk and prosthetic replacement of the pulmonary valve with a ball valve or xeno-graft. Original techniques of radical correction of the Ebstein anomaly and tetralogy of Fallot are presented.

Adult↗
PubMed1979

Measurement of haemolysis in patients with prosthetic heart valves.

Haemolysis following prosthetic heart valve insertion can be precisely and sensitively measured by means of a 59Fe ferrokinetic technique. Results obtained in a small series of patients with either Starr-Edwards or Brunwald-Cutter valve replacement are presented.

Aortic Valve↗