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Query: UMLS:C0033377 (prolapse)
 11,717 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Two Hancock Model 242 prostheses, tissue anulus diameter 21 mm., were tested in a closed, low-volume, accelerated fatigue tester. The fluid media was sterils fresh-frozen plasma. The normal human aortic root was simulated. The cyclic rate was 20 Hz at 37 degrees C. The prostheses developed severe fatigue at 77 million cycles. Fraying of the free edges was found after 2 million cycles. Small tears near the commissures and then holes between collagen bundles at the base of the leaflets appeared at 7 million cycles. At 71 million cycles the leaflets began to tear and complete prolapse, with gross valvular insufficiency occurring at 77 million cycles. The accelerated wear of Hancock procine prosthesis is frequency dependent and independent of media and the flow geometry of the testing device.
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PMID:In vitro durability of Hancock Model 242 porcine heart valve. 57 54

Straited membranous structures (SMS), which consisted of sheets or ribbons of 130 to 220 A in thickness, showed variable patterns of periodic substructure, and resembled SMS described in renal and ocular tissues in various diseases, were found in extracellular locations in a) mitral valve (2 patients) and tricuspid valve (1 patient) of 2 patients with mitral valvular prolapse, b) mitral valve and femoral artery of 1 patient with Marfan's syndrome and prolapsed mitral valve, and c) myocardium (2 patients) and thickened endocardium (3 patients) of 3 patients with congenital heart disease associated with muscular obstruction to right ventricular outflow. Striated membranous structures measured up to several microns in diameter, often were highly folded and convoluted, and sometimes appeared circular in outline. Some SMS measured from 130 to 150 A in thickness and had indistinct edges and poorly defined periodicity. The majority of SMS, however, had greater thicknesses, in the range of 200 A, and a periodicity characterized by alternating light and dark bands with a spacing that varied from 100 to 160 A. The structures were associated with thickened basement membranes, elastic fibers, and membrane-bound bodies of the type thought to be involved in elastogenesis. Evidence available suggests that SMS results from an unusual pattern of arrangement of a component, possibly Type IV collagen, of basement membrane material.
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PMID:Striated membranous structures in human hearts. An ultrastructural study. 97 Apr 44

Long-term experience with first generation porcine valve xenografts enabled identification of the major limitations to their durability: (1) prosthetic-ventricular mismatch due to the high profile of the stent in patients with mitral stenosis and a small left ventricle; (2) high-pressure fixation with loss of natural collagen crimping in the fibrosa, and wash-out of proteoglycans in the spongiosa; (3) xenograft tissue autolysis, due to the long interval between animal slaughter and aortic valve removal fixation; (4) muscle shelf in the right coronary cusp, which created a gradient and could undergo accelerated calcification and/or spontaneous perforation with time; (5) a flexible polypropylene stent, which could creep or even fracture with consequent inward bending of the stent; (6) progressive time-related dystrophic calcification; (7) host fibrous tissue ingrowth. An awareness of these limitations stimulated technical modifications, which frequently brought about distinct improvements: (1) the reduction of the stent profile eliminated the problem of mismatch, but resulted in a higher tendency towards cusp prolapse and earlier commissural tearing; (2) natural collagen waviness, proteoglycans and cusp extensibility were preserved by employing low or even zero pressure during the fixation process; (3) earlier valve fixation enabled preservation of cell integrity; (4) a new orifice for small valves was designed by replacing the right muscular cusp, thus achieving less gradient and avoiding muscle-shelf-related complications; (5) polypropylene was replaced by Delrin as stent material; (6) calcium-retarding agents like T6 and toluidine blue were applied during commercial processing and storage in order to mitigate tissue mineralization.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Heart valve bioprosthesis durability: a challenge to the new generation of porcine valves. 138 86

From 1981 to 1987 just over 608 Ionescu-Shiley low-profile bovine pericardial bioprostheses were implanted at the Toronto Hospital. Twenty-four prostheses (11 aortic and 13 mitral) were surgically explanted from 1988 to 1990 from 20 adults (10 men and 10 women). Prosthesis failure was caused by primary tissue failure in 17 valves or by other mechanisms in seven valves. Variable degrees of tissue failure were also seen in four of the seven valves from the latter group. Primary tissue failure was characterized by fluid insudation between collagen bundles, para stent post tears (alignment stitch related, 20 valves), cusp perforation with prolapse, and calcification. The earliest cusp tears occurred at 28 months. Calcification (10 of 24 cases) was minimal in seven of 10 valves (occurring primarily at the margins of the torn cusp), moderate in two, and severe in one. Tissue overgrowth (pannus) was seen in all but three prostheses. Like its predecessor, the Ionescu-Shiley standard pericardial valve, this prosthesis failed at 2 to 5 years largely due to design-related (alignment stitch) causes and tissue degeneration. Calcification was less prominent, while tissue overgrowth (pannus) was more marked.
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PMID:Morphologic findings and causes of failure in 24 explanted Ionescu-Shiley low-profile pericardial heart valves. 850 46

Mitral prolapse is a parachute-like protrusion of the value into the left atrium. Almost always a myxoid degeneration of the valve is the base of such a prolapse. Myxoid degeneration is understood as dissolution of the collagenous fibrous layer and its replacement by acid glucosaminoglycans. An alteration of collagen is suspected as primary defect in this sometimes also inherited disorder. The electron microscope reveals fragmentation of collagen fibrils and elastic fibers and, within the myxoid material, free lysosomes, so called "matrix-vesicles". An isolated disturbance of collagen types I and III could not be detected by immunohistochemistry. Studies could also to date not demonstrate mutations in the genes coding for collagens.
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PMID:[Pathology of myxoid mitral valve degeneration: literature review and personal results]. 144 33

Collagen plays an important physiological role in the process of wound healing and the possibility of using lyophilized collagen has opened up prospects in surgery. The author reports his experience in gynaecological surgery: myomectomy, vaginal or abdominal hysterectomy and repair surgery for vaginal prolapse with hysterectomy and cystourethropexy. The results obtained suggest the use of lyophilized collagen in the above-mentioned cases and a possible wider application in gynaecological surgery.
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PMID:The use of lyophilized collagen in gynaecology. 163 84

The naso-labial fold is a permanent depression of the face which corresponds to the combined action of congenital and acquired factors such as cutaneous atrophy, bone resorption, muscular activity and skin ptosis. It is therefore not realistic to abandon any attempt to correct this complaint or to provide a universal solution to correct it; over the last four years, we have used EPTFE implants to fill the naso-labial fold: triangular, in one or two layers introduced via a gingival incision for the upper naso-labial part, with 2 mm large strips directly inserted through the skin for the lower labio-mental part. Tolerance and versatility were always remarkable; efficacy depends on the possible associated cutaneous ptosis: if major, a lifting procedure, more or less extensive, must be offered, which may also improve the projection of the malar area with an implant of the same material introduced via an oral or temporal approach. All other well known procedures (liposuction, fat grafts, collagen, etc.) may be employed but only as a complement to filling and traction procedures.
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PMID:[The naso-labial fold: analysis and proposed techniques for correction]. 170 74

The solitary rectal ulcer syndrome is an infrequent entity consisting of a rectal lesion, caused by straining during defecation; it is characterized by specific histological changes. The condition is most frequent in adults between 30 and 50 years of age, but a few pediatric cases have been reported. Five patients (4 boys) are presented. All suffered from moderate rectal bleeding, straining, tenesmus and mucous discharge. One of them had clinical and endoscopic evidence of rectal prolapse. On defecography all children showed failure of pelvic floor relaxation during straining. Endoscopic evaluation showed single or multiple ulcers in four patients and a nodular fibrotic lesion in one. The histopathology of the rectal mucosa revealed replacement of the stroma of the lamina propria by collagen, lack of orientation of smooth muscle fibers and considerable hyperthopy of the muscularis mucosae. Medical treatment was satisfactory in four patients, one case required transabdominal rectopexy for relief of his symptoms. The most appropriate form of treatment has not been determined, but surgery should be used when prolapse is a prominent clinical feature. Greater awareness of this condition will lead to more frequent diagnosis.
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PMID:[Solitary rectal ulcer syndrome]. 184 44

We treated two patients with annular epiretinal membranes that produced unusual macular morphologic characteristics. Contracture of the membranes caused herniation of macular tissue through a hole in the center of the membrane. The membranes were removed surgically, and ultrastructural analysis disclosed cells with properties resembling myofibroblasts and apparent new vitreous collagen. Contracture of the cellular components probably produced tangential traction on the retina, which caused prolapse of the retinal tissue through a central defect in the membrane.
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PMID:Epiretinal membrane contracture associated with macular prolapse. 224 24

The gross criteria for diagnosing prolapsing mitral valve are: 1. interchordal hooding of the involved leaflets, 2. hooding or doming of leaflets towards the left atrium, 3. elongation of the involved leaflets resulting in an increase in valve area, 4. dilatation of the valve annulus in patients with severe mitral regurgitation. The posterior leaflet is most frequently affected. The involved leaflets, in general, are thickened, soft, greyish white and have a smooth atrial surface. Chordae tendineae are described as elongated, tortuous and attenuated or thinned. Deviations from normal chordal insertion have recently been observed which possibly appear to represent the underlying abnormality. Microscopic findings include significant thickening of the spongiosa and the fibrosa, changes in dense collagen fibers in the atrialis layer, occasionally, with fibrin platelet deposits. Histochemical characterization of changes in the spongiosa may also be helpful in the diagnosis. Ultrastructurally, there may be changes in collagen and elastic fibers as well as myxoid areas. On comparison of findings in surgically-removed mitral valves with those of control specimens from autopsy patients with no cardiac abnormalities, the length of the anterior and posterior leaflet as well as the annular ring diameter was larger in the valves with prolapse. Two-dimensional echocardiography accurately assessed leaflet length when compared to morphologic measurements, however, the annular diameter during systole or diastole was smaller. In patients with mitral regurgitation requiring surgery, mitral valve prolapse is the most common cause. Annular ring dilatation and chordae tendineae rupture appear to contribute substantially to incurrence of the mitral regurgitation. The heart weight is increased in the majority of patients with symptomatic mitral valve prolapse but normal, however, in those without symptoms. The most frequent complication of mitral valve prolapse is mitral regurgitation with or without congestive heart failure. Patients with redundant leaflets may be at high risk of sudden death. Young women with abnormal resting ECG, prolonged Q-T interval, family history of sudden death or complex ventricular arrhythmias may also be at a greater risk of sudden death. The incidence of infective endocarditis appears higher in those with redundant than in those with nonredundant valves. The incidence of cerebral ischemic events is low.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:The pathology of mitral valve prolapse. 304 84


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