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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↗
PubMedDate not supplied

[Similarities in morphologic changes in heart valves in acquired heart defects of noninflammatory etiology and in damaged menisci without a history of trauma].

Histologic, histochemical and ultrastructural analyses were performed of the leaflets of all four heart valves in 50 subjects with acquired heart defects of noninflammatory etiology and 88 surgically removed damaged menisci without trauma anamnesis. On the basis of the detailed analysis some morphologic similarities were found in the heart valves and menisci such as myxomatous degeneration as the main pathologic lesion, lack of blood vessels in the altered tissues which point to noninflammatory nature of the lesion, similarity in nourishment by diffusion, degradation of the collagenous fibres which present the main histologic structure and the increased accumulation of acid mucopolysacharrides at the site of their degradation as well as the increased number of fibroblasts, that is, chondroid cells which are considered to excrete acid mucopolysacharrides. Sometimes these changes are hardly identify clinically, especially in meniscal diseases which could simulate rheumatic disease.

Adolescent↗
PubMedDate not supplied

Issues surrounding the preservation of viable allograft heart valves.

Allograft heart valves have been used for over 30 years. During the first decades of use, the research and clinical objectives were to find a means for long-term storage of tissue. Methods such as irradiation, glutaraldehyde fixation, long-term antibiotic storage at 4 degrees C and other methods were common. These methods, however, were found to give reduced long-term clinical performance when compared with viable fresh tissue or tissue which had been cryopreserved. Recognizing this fact, more recent emphasis has been to address issues surrounding means by which allografts can be cryopreserved and thawed to retain maximum viability. An additional concern was to find a means to maximize donor retrieval by salvaging tissue which normally would be discarded because of bacterial contamination. This study demonstrates that when a proper cryopreservation technique is used, with stringent antibiotic treatments, biomechanical parameters remain normal with only a slight decrease in cell viability.

Adult↗
PubMed1991

[Risks of combined surgical treatment of acquired heart valve defects and coronary heart disease].

In the past years the number of patients with combined treatment of the heart valves and coronary arteries rised as well as the patients age did. In 1980-1987 the rate of patients with aortic valve replacement and simultaneous aorto-coronary bypass was 10.9% in those who underwent aortic valve replacement and 2.9% in those who had aorto-coronary bypass operation. Since 1988 the ratios changed to 18.2% and 4.9%. For the calculation of the operative risk of the combined operative treatment (AVR + CABG, MVR + CABG) we compared these groups with those patients with isolated operations (MVR, AVR, CABG). We studied all patients during 1980 and July 1989. The hospital mortality of combined procedures was significantly increased. The mortality among female patients was higher as compared to the male group. The age of patients treated by the combined procedures was higher as compared to the isolated procedures. The mean age of the patients which died was severely increased as compared to the isolated procedures. However, in the combined procedures this increase was not as pronounced as in the isolated groups. Patients with combined procedures had a higher NYHA class. The risk factors of the combined procedures were comparable to isolated CABG.

Aortic Valve↗
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↗
PubMed1992

[Long-term clinical results after aortic valve replacement with mechanical heart valves and mitral valve replacement with porcine valves].

Long-term clinical results of aortic valve replacement (AVR) with mechanical heart valves and mitral valve replacement (MVR) with porcine valves were analysed. Sixty-three patients received isolated AVR and 48 received isolated MVR. Sixty-eight patients with MVR including double or triple valve replacement were also added in order to evaluate the primary tissue failure (PTF). The patients with operative deaths were excluded. Survival rate at 11 years in AVR was 68 +/- 10% and 67 +/- 15% in MVR without statistical difference. At 11 years, 76 +/- 8% of the patients in AVR were free from valve-related complications in contrast with the poor result of 34 +/- 31% in MVR (p less than 0.01). Main cause of this poor result in MVR was PTF as indicated in following event free rates; 83 +/- 9% at 7 years, 61 +/- 25% at 10 years and 49 +/- 31% at 13 years. There was no statistical difference between patients of above 50 years and below 49 years in PTF. Valve-related death event free was 93 +/- 5% in AVR and 86 +/- 11% in MVR at 11 years (not significant), however, there was statistical difference in re-operation event free rate as 94 +/- 5% in AVR and 76 +/- 11% in MVR at 11 years (p less than 0.001). These results suggest that the use of porcine valves in mitral position is confined to the selected patients.

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↗
PubMed1991

Principle of operation, design criteria and fluid dynamics of a new bileaflet heart valve prosthesis.

Bileaflet heart valves show the best fluid dynamic behaviour among mechanical valves and, as a consequence, give the best clinical results. A new bileaflet heart valve has been designed whose main characteristics are the kind of leaflet movement, low profile, fluid dynamics and material. Two flat leaflets move freely inside a very low profile housing ring. The movement is described by the rolling without sliding of the leaflet surface around a cylindrical surface on the inner wall of the housing. The opening angle is 85 degrees. Both the leaflets and the housing are machined from a solid piece of titanium and then covered with carbon by ion beam techniques. The design phase and the first fluid dynamic evaluation were done by numerical methods.

Carbon↗
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↗