Lymphocyte-rich capillary-cavernous hemangioma of the mitral valve: a case report and review of the literature

Valvular hemangioma incidence is extremely low. In this report, we describe a 62-year-old man who presented with mild edema of the lower limbs. An echocardiogram revealed an incidental 1.3-cm diameter mass on the anterior mitral valve leaflet for which he underwent surgical resection and mitral valve replacement. Histopathological examination showed a lymphocyte-rich capillary-cavernous hemangioma. The exuberant lymphoid stroma is unusual for hemangioma and represents an undescribed pattern of cardiac hemangioma. Including the present report, only 13 cases of mitral valve hemangioma have been reported to date. Most patients are adult. Mitral hemangioma originates in the atrial aspect of the valve and involves more commonly the anterior leaflet. The average maximum diameter of the lesion is 1.7 (S.D.=0.75) cm. Pure cavernous hemangioma is the predominant type of mitral hemangioma. Most of them are described as pedunculated or polypoid. Surgical excision appears to be curative. Recurrences have not been reported. Lymphocyte-rich cardiac hemangioma represents a peculiar type of hemangioma which should be included in the differential diagnosis of other vascular lesions.

Rheumatic Heart Disease and Myxomatous Degeneration: Differences and Similarities of Valve Damage Resulting from Autoimmune Reactions and Matrix Disorganization

Autoimmune inflammatory reactions leading to rheumatic fever (RF) and rheumatic heart disease (RHD) result from untreated Streptococcus pyogenes throat infections in individuals who exhibit genetic susceptibility. Immune effector mechanisms have been described that lead to heart tissue damage culminating in mitral and aortic valve dysfunctions. In myxomatous valve degeneration (MXD), the mitral valve is also damaged due to non-inflammatory mechanisms. Both diseases are characterized by structural valve disarray and a previous proteomic analysis of them has disclosed a distinct profile of matrix/structural proteins differentially expressed. Given their relevance in organizing valve tissue, we quantitatively evaluated the expression of vimentin, collagen VI, lumican, and vitronectin as well as performed immunohistochemical analysis of their distribution in valve tissue lesions of patients in both diseases. We identified abundant expression of two isoforms of vimentin (45 kDa, 42 kDa) with reduced expression of the full-size protein (54 kDa) in RHD valves. We also found increased vitronectin expression, reduced collagen VI expression and similar lumican expression between RHD and MXD valves. Immunohistochemical analysis indicated disrupted patterns of these proteins in myxomatous degeneration valves and disorganized distribution in rheumatic heart disease valves that correlated with clinical manifestations such as valve regurgitation or stenosis. Confocal microscopy analysis revealed a diverse pattern of distribution of collagen VI and lumican into RHD and MXD valves. Altogether, these results demonstrated distinct patterns of altered valve expression and tissue distribution/organization of structural/matrix proteins that play important pathophysiological roles in both valve diseases.

The Role of Interleukin-13 in Patients with Rheumatic Valvular Fibrosis: A Clinical and Histological Study

BACKGROUND AND AIM OF THE STUDY

Interleukin (IL)-13 is a major inducer of fibrosis in many chronic infectious diseases, yet few studies have reported its role in valvular fibrosis in patients with rheumatic heart disease (RHD). The study aim was to investigate the role of IL-13 in mitral valvular fibrosis in patients with RHD.

METHODS

Peripheral blood samples were collected from surgical patients with RHD (n = 18) and from healthy controls (n = 9). Serum levels of IL-13 and interferon (IFN)-gamma were analyzed using ELISA. Rheumatic mitral valves removed from surgical patients with RHD, and normal mitral valves, were obtained at autopsy. The expression and distribution of collagen I, collagen III, and IL-13Ralpha1 were examined by immunohistochemical staining, the degree of which was measured using computed imaging analysis.

RESULTS

Higher IL-13 levels were observed in RHD patients (15.16 +/- 9.62 pg/ml; p < 0.05) than in healthy controls (7.78 +/- 3.87 pg/ml). RHD patients had high levels of IFN-gamma (9.95 +/- 0.77 pg/ml; p <0.05) compared to healthy controls (5.95 +/- 0.69 pg/ml). Immunohistochemistry showed that, compared to normal valves, rheumatic mitral valves expressed high levels of collagen I (0.01931 +/- 0.00159 versus 0.01183 +/- 0.00207; p < 0.05), collagen III (0.00726 +/- 0.00078 versus 0.00342 +/- 0.00124; p <0.05), and IL-13Rcxl (0.00454 +/- 0.00086 versus 0.00017 +/- 0.00008; p <0.01). Collagens I and III were each expressed in heart interstitial cells, while IL-13Ralpha1 was expressed in the endothelial cells and smooth muscle cells of the blood vessels, and in interstitial cells.

CONCLUSION

Patients with RHD showed increased serum levels of IL-13 compared to healthy controls. IFN-gamma levels were clearly different among RHD patients and healthy controls. The expression of collagens I and III and IL-13Ralpha1 was higher in rheumatic mitral valves compared to normal mitral valves. IL-13 may induce mitral valvular fibrosis in RHD.

Heart valve collagens: cross-species comparison using immunohistological methods

BACKGROUND AND AIM OF THE STUDY

Tissue engineering is an emerging strategy for the development of replacement heart valves where the properties of native tissues are to be replicated. The complexity of the distribution of various collagens in the aortic, mitral, and pulmonary valve leaflets of porcine, bovine, and ovine origin, has been examined.

METHODS

Immunohistological and transmission electron microscopy analyses using monoclonal antibodies to types I, III, IV, V and VI collagens were performed.

RESULTS

The results indicated that each collagen type has its own distinct distribution, with minimal variation between heart valve anatomic sites and species. Of particular interest was type VI collagen, which had an asymmetric distribution that was principally localized along the outflow surface of the valve.

CONCLUSION

Successful tissue engineering constructs of heart valves may need to replicate the complex distribution of different collagens found in heart valve tissues.

PDIA3, HSPA5 and vimentin, proteins identified by 2-DE in the valvular tissue, are the target antigens of peripheral and heart infiltrating T cells from chronic rheumatic heart disease patients

Rheumatic fever (RF) is a post-infectious autoimmune disease due to sequel of group A streptococcus (GAS) pharyngitis. Rheumatic heart disease (RHD), the major manifestation of RF, is characterized by inflammation of heart valves and myocardium. Molecular mimicry between GAS antigens and host proteins has been shown at B and T cell level. However the identification of the autoantigens recognized by B and T cells within the inflammatory microenvironment of heart tissue in patients with RHD is still incompletely elucidated. In the present study, we used two-dimensional gel electrophoresis (2-DE) and mass spectrometry to identify valvular tissue proteins target of T cells from chronic RHD patients. We could identify three proteins recognized by heart infiltrating and peripheral T cells as protein disulfide isomerase ER-60 precursor (PDIA3), 78kD glucose-regulated protein precursor (HSPA5) and vimentin, with coverage of 45%, 43 and 34%, respectively. These proteins were recognized in a proliferation assay by peripheral and heart infiltrating T cells from RHD patients suggesting that they may be involved in the autoimmune reactions that leads to valve damage. We also observed that several other proteins isolated by 2-DE but not identified by mass spectrometry were also recognized by T cells. The identified cardiac proteins are likely relevant antigens involved in T cell-mediated autoimmune responses in RF/RHD that may contribute to the development of RHD.

[Myxomatous mitral valve degeneration: biochemical aspects and physiopathological considerations]

Mitral valve is a complex structure which is submitted to repeated mechanical constraints. In clinical practice, an increasing incidence of mitral insufficiency resulting from myxomatous degeneration is observed. Since myxomatous degeneration is also observed in defined genetic diseases of connective tissues, we propose the hypothesis that idiopathic mitral insufficiency might result from a minor alteration of the interstitial valvular cells and/or their interactions with their support. After a brief review of the role of the extracellular matrix in the heart, some histopathological and biochemical aspects of myxomatous degeneration are presented. Our data and those of the literature will be summarized and a physiopathological hypothesis proposed for myxomatous mitral valve degeneration.

Differential protein kinase C isoform abundance in ascending aortic aneurysms from patients with bicuspid versus tricuspid aortic valves

BACKGROUND

It is recognized that different events contribute to the initiation of ascending thoracic aortic aneurysms (ATAAs) in patients with bicuspid aortic valves (BAV) versus patients with tricuspid aortic valves (TAV), but the molecular signaling pathways driving aneurysm formation remain unclear. Protein kinase C (PKC) is a superfamily of kinases which differentially mediate signaling events that lead to altered gene expression and cellular function, and may regulate downstream mediators of vascular remodeling. The present study tested the hypothesis that ATAA development in patients with BAV versus TAV proceeds by independent signaling pathways involving differential PKC signaling.

METHODS AND RESULTS

ATAA samples were collected from BAV (n=57) and TAV (n=55) patients and assessed for 10 different PKC isoforms by immunoblotting. Results were expressed as a percent change in abundance (mean+/-SEM) from a nonaneurysmal control group (100%, n=21). Correlation analysis was performed, and relationships between PKC and matrix metalloproteinase abundance were reported. In the BAV group, classic and novel PKC isoforms (PKC-alpha, betaI, gamma, epsilon, theta) were increased, whereas PKC-eta and atypical PKC-zeta were decreased. In the TAV group, classic and novel isoforms were decreased and atypical PKC-zeta was elevated. Positive correlations between PKC and matrix metalloproteinase abundance were identified.

CONCLUSIONS

Differential PKC isoform abundance was observed in ATAA samples from patients with BAV versus TAV, suggesting independent molecular signaling pathways may be operative. Induction of independent transcriptional programs may result and may provide a mechanistic foundation for developing selective diagnostic/therapeutic strategies for patients with ATAAs secondary to BAV or TAV.

Fine characterization of mitral valve glycosaminoglycans and their modification with degenerative disease

BACKGROUND

The levels and fine structure of complex polysaccharides, glycosaminoglycans (GAGs), were determined in segments of the posterior mitral valve leaflet (MVL) taken from 15 patients affected by mitral regurgitation and degenerative disease and were compared with segments from 15 multiorgan donors.

METHODS

MVL GAGs were analyzed by agarose gel electrophoresis, and by HPLC and fluorophore-assisted carbohydrate electrophoresis to evaluate disaccharide patterns after treatment with chondroitinase ABC.

RESULTS

GAGs from the control group were composed of approximately 37% hyaluronic acid and 63% chondroitin sulfate/dermatan sulfate with a charge density of approximately 0.61. Chondroitin sulfate/dermatan sulfate polymers contained approximately 23% of the disaccharide sulfated in position 6 on N-acetyl-galactosamine, approximately 38% of the 4-sulfated disaccharide and approximately 2% of the non-sulfated disaccharide (with a 4-sulfated/6-sulfated ratio of 1.7). The total amount of GAGs was 0.66 microg/mg tissue. The total amount of GAGs in patients suffering from mitral regurgitation and degenerative disease was approximately 51.5% higher (although the difference was not significant, probably because of the low number of subjects enrolled in the study). However, significantly higher hyaluronic acid content (approx. +38%, p<0.05) and lower sulfated GAG content (approx. -21%, p<0.005) were demonstrated. As a consequence, the total charge density decreased by approximately 23% (p<0.005). This macro-modification of GAG composition was also followed by a micro-alteration of the structure of the sulfated polysaccharides, in particular with a significant decrease in the 4-sulfated disaccharide (and a parallel increase in hyaluronic acid content) with no modification of the percentage of the 6-sulfated and non-sulfated disaccharides (with a significant decrease in the 4-/6-sulfated ratio).

CONCLUSIONS

We assume that changes in the relative amount and distribution of GAGs in posterior MVL in subjects suffering from mitral regurgitation and degenerative disease are consistent with a decrease in the tension to which these tissues are subjected and with an abnormal matrix microstructure capable of influencing the hydration and of conditioning the mechanical weakness of these pathological tissues.

Increased nitric oxide release and expression of endothelial and inducible nitric oxide synthases in mildly changed porcine mitral valve leaflets

BACKGROUND AND AIM OF THE STUDY

Little is known of the local role of nitric oxide (NO) in heart valves in relation to heart valve diseases. The study aim was to examine NO release and the expression of both endothelial nitric oxide synthase (eNOS) and inducible nitric oxide synthase (iNOS) in relation to early local changes in porcine mitral valves.

METHODS

A histological evaluation of mitral valve leaflets from slaughter pigs and sows was made, and the expression of eNOS and iNOS protein measured using immunohistochemistry. Furthermore, mRNA levels of eNOS and iNOS were measured using real-time RT-PCR. A calibrated NO-specific electrode was used to measure local NO release in specific regions of the anterior mitral leaflet from slaughter pigs and sows interchordally at the tip of the leaflet (region A), at the chordal insertion (region B), and at the center of the leaflet (region C).

RESULTS

Leaflets from sows had an increased accumulation of mucopolysaccharides (MPS) compared to those from slaughter pigs. Furthermore, mRNA levels of eNOS and iNOS were significantly increased in region C due to very high levels of expression in some sow leaflets. NO release in the sow mitral valve leaflet was increased in regions B and C compared to that in region A.

CONCLUSION

The relative distribution of NO release is increased in regions of porcine mitral valve leaflets with deposition of MPS and defraction of the valve structure, which may reflect changes in both eNOS and iNOS expression.

Evaluation of glycosaminoglycans content and 5-hydroxytryptamine 2B receptor in the heart valves of Sprague-Dawley rats with spontaneous mitral valvulopathy – A possible exacerbation by dl-amphetamine sulfate in Fischer 344 rats?

Spontaneous valvulopathy has been described as nodular or segmental thickenings composed of fibromyxoid tissue in the subendocardium of various valve-leaflets in aging rats, but its pathogenesis and significance are incompletely understood. In this study, we examined the 5-hydroxytryptamine 2B receptor (5HT2BR) expression and characterization of extracellular matrix (ECM) components, and related these to the presence of valvulopathy in the mitral valve-leaflet (spontaneous mitral valvulopathy, SMV) of Sprague-Dawley (SD) rats. We also examined hearts from Fischer 344 (F344) rats treated with dl-amphetamine sulfate for 103 weeks to further explore the potential for drug-induced exacerbation of SMV. In SD rats, valve-leaflets with SMV exhibited a greater valve thickness, a higher amount of glycosaminoglycans, a lower amount of collagen and increased number of 5HT2BR-positive cells. Our data on morphology and ECM changes showed a striking similarity between SMV in SD rats and anorexigen-associated valvulopathy in humans, and increased 5HT2BR-positive cells in SMV implies that 5HT2BR may play a role in pathogenesis. Further, increased incidence and severity of SMV in F344 rats by treatment with dl-amphetamine suggest that a drug-induced exacerbation of SMV may exist in rats. However, additional research is needed to confirm a role for 5HT2BR in the pathogenesis of SMV in SD rats, and to further characterize the relationship between dl-amphetamine treatment and exacerbation of SMV in F344 rats.

Usefulness of cardiac calcification on two-dimensional echocardiography for distinguishing ischaemic from nonischaemic dilated cardiomyopathy: a preliminary report

BACKGROUND

Aortic valve calcification (AVC) and/or mitral annulus calcification (MAC) is considered to be a marker of atherosclerosis and has been demonstrated to predict cardiovascular morbidity and mortality.

AIM

We hypothesized that the presence of cardiac calcification by echocardiography can be used in the differential diagnosis between ischaemic (DCMI+) and nonischaemic dilated cardiomyopathy (DCMI-).

METHODS

We evaluated 62 patients with DCM (38 males, mean age 66 +/- 10 years, LVEF < 40%), without any prior history of myocardial infarction or coronary intervention, who were undergoing coronary angiography for aetiological diagnosis. DCMI+ was considered present when a > or = 70% stenosis of at least one coronary artery was found. AVC, MAC, aortic wall and papillary muscle calcifications were semiquantitatively assessed by two-dimensional echocardiographic examination with a calcium score ranging from 0 (no calcifications) to 8 (calcium in all four sites).

RESULTS

DCMI+ was found in 20 out of 62 patients. As expected, there were no differences in LVEF and LV end-diastolic diameters between DCMI+ and DCMI--patients (29 +/- 8% versus 31 +/- 10% and 66 +/- 6 versus 68 +/- 8 mm, respectively; not significant). Regional wall motion abnormalities and conventional risk factors for atherosclerosis, such as hypertension and hypercholesterolaemia, were significantly more frequent in the DCMI+ compared to the DCMI- group. On the other hand, the calcium echo score was 4.6 +/- 2 (range 1.7-7.3) in DCMI+ patients and 0.8 +/- 0.95 (range 0-4) in DCMI--patients (P < 0.05). A calcium score > or = 3 was observed in 18 out of 20 (90%) DCMI+ patients and only in three of 42 (8%) DCMI--patients.

CONCLUSIONS

The assessment of cardiac calcification by two-dimensional echocardiography could represent a simple, noninvasive and inexpensive approach to assess the aetiology (ischaemic versus nonischaemic) of dilated cardiomyopathy.

Normal distribution of melanocytes in the mouse heart

We report the consistent distribution of a population of pigmented trp-1-positive cells in several important septal and valvular structures of the normal mouse (C57BL/6) heart. The pigmented cell population was first apparent by E16.5 p.c. in the right atrial wall and extended into the atrium along the interatrial septum. By E17.5, these cells were found along the apical membranous interventricular septum near or below the surface of the endocardium. The most striking distribution of dark pigmented cells was found in the tricuspid and mitral valvular leaflets and chordae tendineae. The normal distribution of pigmented cells in the valvuloseptal apparatus of C57BL/6 adult heart suggests that a premelanocytic lineage may participate in the earlier morphogenesis of the valve leaflets and chordae tendineae. The origin of the premelanocyte lineage is currently unknown. The most likely candidate populations include the neural crest and the epicardially derived cells. The only cell type in the heart previously shown to form melanocytes is the neural crest. The presence of neural crest cells, but not melanocytes, in some of the regions we describe has been reported by others. However, previous reports have not shown a contribution of melanocytes or neural crest derivatives to the atrioventricular valve leaflets or chordae tendineae in mouse hearts. If these cells are of neural crest origin, it would suggest a possibly greater contribution and persistence of neural crest cells to the valvuloseptal apparatus than has been previously understood.

Structural Characterization of the Chordae Tendineae in Native Porcine Mitral Valves

BACKGROUND

This study was aimed to characterize the different mitral valve chordae tendineae to provide additional understanding of their function.

METHODS

Mitral valve chordae tendineae from fresh porcine hearts were stained for collagen and elastin using either a Verhoeff and van Gieson stain or Verhoeff light green stain. Cellular distribution was determined using a hematoxylin and eosin stain. Immunohistochemistry was used to verify the findings of vasculature. Biochemical assays were performed to quantify DNA, collagen, and elastin content of each of the six different types of chordae tendineae.

RESULTS

Blood vessels were observed in the longitudinal and circumferential directions of the chordae. The strut chordae on the anterior leaflet of the mitral valve showed an increased degree of vascularization compared with the other chordae. All chordae had an inner layer characterized by a high concentration of collagen and an outer layer that was mostly elastin with interwoven collagen fibers. The collagen microstructure was characterized by directional crimping. Hematoxylin and eosin staining showed fibroblasts evenly distributed throughout the inner and outer layer of the chordae tendineae. Quantitative analysis showed significantly higher levels of DNA and collagen content in the anterior and posterior marginal chordae compared with the other chordae.

CONCLUSIONS

The chordae tendineae were seen to have different microstructures according to chordal type. The presence of vessels characterized the chordae tendineae as complex living components that work in coordination with the papillary muscles and mitral valve leaflets to prevent mitral valve prolapse and regurgitation. They may also function to supply nutrients to the valve leaflets.

Relation of decreased ankle-brachial index to prevalence of atherosclerotic risk factors, coronary artery disease, aortic valve calcium, and mitral annular calcium

Coronary artery disease was present in 89 of 118 patients (75%) with a decreased ankle-brachial index (ABI) and in 34 of 118 age- and gender-matched patients (29%) with a normal ABI (p <0.001). Aortic valve calcium or mitral annular calcium was present in 81 of 118 patients (69%) with a decreased ABI and in 43 of 118 patients (36%) with a normal ABI (p <0.001).

Is the mitral valve passive flap theory overstated? An active valve is hypothesized

The concept that the mitral valve of the heart is a passive flap that opens and closes like a barn door has been emphasized for decades by medical and biology professors to their students. But experimental findings, which are outlined in this report, support the theory of an active valve. We hypothesize that the two leaflets of the mitral valve are actively contractile; that physical forces generated in the valve itself may stabilize and add precision to the sum of forces that regulate valve movement. This precision could be of critical significance both in the moments preceding, and during, valve opening and closing. Evidence supporting our active valve hypothesis includes the profuse innervation of motor and sensory nerves that are present in the mitral valves of all animals studied. In addition, multiple contractile cell types have been found in the mitral valve, including cardiac muscle cells, smooth muscle cells, and cardiac valvular interstitial cells. In vitro work in our laboratories using the rat mitral valve shows that not only are the valves capable of contraction and relaxation, but that the contractions and relaxations are nerve-mediated. We theorize that the rich innervation and contractile cells in the mitral valve work together to modulate fine-tuning of valve movements and tone, thereby ensuring the integrity of the valve seal. Other investigators have reported that the mitral valve demonstrates contractile activity and that denervation localized to the mitral valve affects valve competence. The evidence for an active mitral valve presented by these and other experimental studies warrant a reexamination of the validity of the passive valve concept. An accurate and full understanding of the precise movements of the valve leaflets and the mechanisms that regulate these movements is likely to provide the information needed to understand and develop treatments for many different cardiac valve problems, including mitral valve diseases such as prolapse and myxomatous degeneration. In view of the available experimental evidence, the concept that the mitral valve functions only as a passive structure is challenged by numerous anomalies. A reinterpretation of the concept of valve function that incorporates active as well as passive roles for the valve leaflets and other components of the valve apparatus would have significant implications both for the directions taken in research involving the cardiac valves and for the approaches to treatment.

Glycosaminoglycans and proteoglycans in normal mitral valve leaflets and chordae: association with regions of tensile and compressive loading

This study was designed to identify the specific proteoglycans and glycosaminoglycans (GAGs) in the leaflets and chordae of the mitral valve and to interpret their presence in relation to the tensile and compressive loads borne by these tissues. Leaflets and chordae from normal human mitral valves (n = 31, obtained at autopsy) were weighed and selected portions digested using proteinase K, hyaluronidase, and chondroitinases. After fluorescent derivatization, fluorophore-assisted carbohydrate electrophoresis was used to separate and quantify the derivatized saccharides specific for each GAG type. In addition, the lengths of the chondroitin/dermatan sulfate chains were determined. Proteoglycans were identified by western blotting. The regions of the valve that experience tension, such as the chordae and the central portion of the anterior leaflet, contained less water, less hyaluronan, and mainly iduronate and 4-sulfated N-acetylgalactosamine with chain lengths of 50-70 disaccharides. These GAGs are likely associated with the small proteoglycans decorin and biglycan, which were found in abundance in the tensile regions. The valve regions that experience compression, such as the posterior leaflet and the free edge of the anterior leaflet, contained significantly more water, hyaluronan, and glucuronate and 6-sulfated N-acetylgalactosamine with chain lengths of 80-90 disaccharides. These GAGs are likely components of water-binding versican aggregates, which were abundant in the compressive loading regions. The relative amounts and distributions of these GAGs are therefore consistent with the tensile and compressive loads that these tissues bear. Finally, the concentrations of total GAGs and many different chondroitin/dermatan sulfate subclasses were significantly decreased with advancing age.

The challenge of defining normality for human mitral and aortic valves: geometrical and compositional analysis

Advances in digital imaging technology and in tools for obtaining detailed quantitation of morphological features have facilitated a new approach to pathological assessment of many tissues, including heart valves. In the present study, we quantitatively examined the tissue geometry and composition of structurally normal mitral and aortic valves removed at autopsy or surgery from patients aged 15-84 years. Through univariate analyses of quantitative variables, we have determined which features change distinctively with age. The anterior mitral valve leaflet (AMV) underwent a statistically significant decrease in area of the valve proper and an increase in the number of superficial tissue accumulations called onlays as the patients aged. For all geometric variables measured in the aortic valve, increases were seen with age, leading to a thicker valve, with enlargement of the valve proper and onlays, and with changes in the number of onlays. The mitral valve proper, composed largely of collagen in younger individuals, showed significant increases in glycosaminoglycans and elastin and a relative decrease in collagen with age. The compositional characteristics of the aortic valve proper were similar to those of the mitral valve, with a dramatic relative increase in elastin and a decrease in collagen with age. Valve onlays, when present, were similar in composition to the valve proper for both valves. Our findings regarding normal valve tissue composition, when taken in the context of geometrical features, and together with evidence of age-related changes in the relative amounts of specific constituents, provide a basis on which to analyze human heart valves affected by various known or putative diseases.

Haematologic determinants of left atrial spontaneous echo contrast in mitral stenosis

OBJECTIVES

To determine if a relationship exists in mitral stenosis, in patients with either sinus rhythm or atrial fibrillation, between left atrial spontaneous echo contrast and the haematologic indices haematocrit, red cell concentration, mean corpuscular volume, platelet count and volume.

METHODS

Left atrial spontaneous echo contrast severity was graded on a scale of 0-4 in 163 patients with symptomatic mitral stenosis (84 patients in sinus rhythm, 79 patients in atrial fibrillation) undergoing transesophageal echocardiography, cardiac catheterization and full blood examination as part of assessment prior to balloon mitral valvuloplasty.

RESULTS

In sinus rhythm, spontaneous echo contrast grade was negatively correlated with cardiac index (r=-0.33), mitral valve area (r=-0.25) and mitral regurgitation grade (r=-0.22) and positively correlated with haematocrit (r=0.24) and red cell concentration (r=0.25). Spontaneous echo contrast grade was not correlated with left atrial diameter or mean corpuscular volume. In atrial fibrillation, spontaneous echo contrast grade was also negatively correlated with mitral valve area (r=-0.25) and mitral regurgitation (r=-0.36) but was positively correlated with left atrial diameter (r=0.34) and was not correlated with cardiac index, haematocrit or red cell concentration. There was no correlation between spontaneous echo contrast grade and platelet variables in either group.

CONCLUSIONS

Natural variation in red cell concentration in patients with symptomatic mitral stenosis was an independent predictor of the severity of left atrial spontaneous echo contrast in sinus rhythm, but no relationship between red cell concentration and spontaneous echo contrast grade was evident in atrial fibrillation.

Differences in accumulation of elements in human cardiac valves

To elucidate changes of human cardiac valves with aging, the authors determined age-related changes of element contents in the four human cardiac valves by inductively coupled plasma-atomic emission spectrometry and attempted to examine the relationships in the element contents among the four cardiac valves. The subjects consisted of 10 men and 15 women, ranging in age from 65 to 102 yr. The accumulation of calcium and phosphorus was the highest in the aortic valve, and decreased in the order mitral, pulmonary, and tricuspid valves. The contents of calcium and phosphorus in the aortic valves corresponded to about 12 and 19 times the amounts of those in the tricuspid valves, in which the contents were very low. The contents of calcium and phosphorus in the aortic valves were about 2.5-fold the amounts of those in the mitral valves. An examination was attempted to determine whether or not there were relationships in element contents among the four cardiac valves. As for the aortic and mitral valves, there were no relationships in the contents of calcium and phosphorus between them, but there were relationships in the contents of sulfur and magnesium between them. Three out of 24 cases contained high contents of calcium and phosphorus in both the mitral and aortic valves, whereas 16 out of 24 cases contained high contents of calcium and phosphorus in the aortic valves alone, without the high contents in the mitral valves. Likewise, there were no relationships in the element contents, such as calcium, phosphorus, sulfur, and magnesium, between the mitral and pulmonary valves or between the mitral and tricuspid valves. It is suggested that the accumulation of calcium and phosphorus in the cardiac valve occurs independent of the other cardiac valves.

Accumulation of calcium and phosphorus in the mitral valve in comparison with the abdominal aorta and the scaphoid bone

To clarify why calcification of the mitral valve occurred, the authors chose the abdominal aorta and the scaphoid bone among many arteries and bones, and they studied both relationships in element contents between the mitral valve and the abdominal aorta and between the mitral valve and the scaphoid bone. The subjects consisted of 11 men and 8 women, ranging in age from 52 to 96 yr. The accumulation of calcium and phosphorus occurred progressively with aging in the mitral valve, whereas it became the highest in the sixties in the abdominal aorta and did not increase thereafter. The accumulation of calcium and phosphorus occurred in the abdominal aorta earlier than the thoracic aorta, in which it became remarkable in the seventies. It should be noted that in regard to the accumulation of calcium and phosphorus, no significant correlations were found between the mitral valve and the abdominal aorta. It is suggested that calcification of the abdominal aorta is not essentially accompanied by calcification of the mitral valve. The scaphoid bone was chosen among many bones consisting mainly of spongy bone and the relationship was examined between the calcium content in the mitral valve and the bone mineral density of the scaphoid bone. It was found that there was a low relationship between them. Therefore, it is suggested that a part of the surplus calcium released from bones is deposited in the mitral valve.

Age-related changes of element contents in human mitral and tricuspid valves

To examine age-related changes of human cardiac valves, mitral and tricuspid valves were analyzed by inductively coupled plasma-atomic emission spectrometry. The subjects for mitral valves consisted of 12 men and 8 women, ranging in age from 52 to 96 yr. The subjects for tricuspid valves consisted of 11 men and 6 women, ranging in age from 52 to 93 yr. Furthermore, 16 of the samples of the cardiac valves were derived from the same subjects. The contents of calcium, phosphorus, and magnesium in the mitral valves increased progressively with advancing age and reached maximum in the 80s in regard to calcium and phosphorus and maximum in the 90s in regard to magnesium. The maximum average amounts corresponded to about three times the average contents in the 60s. In contrast, the content of sulfur in the mitral valves remained constant between the 50s and 90s. Regarding tricuspid valve, the contents of calcium, phosphorus, and magnesium scarcely increased with advancing age, except for one subject who died of chronic renal failure. Histological observations of the mitral valves revealed that deposits of calcium were present in both the elastic fibers and its degenerative tissues of the mitral valve. The present study indicates that the accumulation of calcium, phosphorus, and magnesium occurs progressively in the mitral valve with aging, but does not occur in the tricuspid valve.

Increased endothelin-receptor density in myxomatous canine mitral valve leaflets

In dogs and humans, myxomatous mitral valve disease results in mitral valve prolapse and mitral regurgitation. Diseased leaflets display endothelial damage, which in turn might lead to subendothelial growth through release of paracrine mediators such as endothelin-1. The aim of the study was to investigate the presence and distribution of endothelin receptors and relate these to the presence and severity of myxomatous valve disease in the dog. Valves with clear macroscopic signs of disease were taken at postmortem from five old dogs. Control valves without macroscopic signs of disease were taken from five young dogs. Endothelin receptors in the leaflets were examined by using radiolabeled endothelin-1 detected by autoradiography. The endothelin-receptor density was graded semiquantitatively. To determine disease severity, adjacent sections stained with periodic acid-Schiff (PAS)/Alcian blue were examined histologically. The leaflet thickness was measured, and the mucopolysaccharide deposition, collagen degeneration, and fibrosis were graded semiquantitatively. Diseased areas displayed high endothelin-receptor densities; normal-looking areas showed low densities. The endothelin-receptor density within as well as on the leaflets correlated positively with all four measures of disease severity in the distal most affected third of the cusps, suggesting that endothelin plays a pathogenetic role in canine myxomatous mitral valve disease.

Immunolocalization of elastin, collagen type I and type III, fibronectin, and vitronectin in extracellular matrix components of normal and myxomatous mitral heart valve chordae tendineae

The identification, distribution, and localization of matrix proteins and the proteins associated with normal and degenerated elastic fibers and collagen fibrils of myxomatous chordae tendineae were studied with immunoelectron microscopy. Ultrathin sections of L R White-embedded tissue were processed by indirect immunogold cytochemistry using primary antibodies against human alpha elastin, collagen types I and III, fibronectin, and vitronectin. In normal chordae tendineae, alpha elastin antibody heavily labeled the elastic fibers in spongiosa and fibrosa, but microfibrils around them were not labeled. Antibodies to collagen type I, collagen type III, and fibronectin all labeled the collagen fibers and microfibrils in the spongiosa. Fibronectin antibody labeling was higher than collagen type III, whereas labeling by anticollagen type I was lower. Intense labeling by vitronectin was observed on the microfibrils in the spongiosa and on electron-dense material around elastic fibers in the spongiosa and fibrosa. In myxomatous chordae tendineae, alpha elastin antibody heavily labeled degenerated elastic fibers, previously unidentified reticulated structures, and other moderately electron-dense material, both in the spongiosa and in the fibrosa, but not the electron-dense fibrous material around them. Antibodies to collagen types I, III, and fibronectin heavy labeled electron-dense aggregates of fibrous material. Vitronectin labeling was observed on electron-dense longitudinally running microfibrils and on the electron-dense microfibrils around degenerated elastic fibers.

Subcellular distribution of prostaglandin-E2 and prostaglandin-F2 alpha in atrial tissue from patients with mitral valve disease

The distribution of prostaglandin-E2 (PGE2) and prostaglandin-F2 alpha (PGF2 alpha) was studied in subcellular fractions isolated from homogenates of human atrial fresh tissue by differential centrifugation. Right and left atrial samples were excised from the same heart of six patients with mitral valve disease at the time of open heart surgery. The atrial fractions investigated were mitochondrial (8,500 g pellet), microsomal (100,000 g pellet) and cytosol soluble (100,000 g supernatant) fractions. After extraction of prostaglandins from the three atrial fractions and separation of PGE from PGF series by chromatography on silicic acid column, these prostaglandins were measured by radioimmunoassay. The results showed that PGE2 and PGF2 alpha were located mainly in the soluble cytosolic fraction of right and left atrial tissue (p < 0.001). Furthermore, the prostaglandins levels were higher in left than in right atria of these patients (p < 0.001). The relation between prostaglandins heart generation in response to elevated work load of mitral valve disease is discussed.

Altered collagen concentration in mitral valve leaflets: biochemical and finite element analysis

BACKGROUND

Ischemic mitral regurgitation or ventricular wall motion abnormalities will alter the stress distribution in the mitral valve. We hypothesize that in response, the regional collagen concentration will be altered and will significantly impact the stress distribution in the mitral valve.

METHODS

Two sheep served as normal (sham) controls. Two other sheep had coronary ligation resulting in abnormal ventricular wall motion. Four sheep underwent ligation to infarct the posteromedial papillary muscle, resulting in ischemic regurgitation. After 4 or 8 weeks, the mitral valves were excised, and the anterior leaflet sections were subjected to an assay for collagen concentration. Next, in a finite element model, to simulate changes in collagen concentration, the tissue stiffness was increased by 20%, and then decreased by 20%. In another model, the thickness of the tissue was increased by 20%, and then combined with decreased tissue stiffness. Physiologic loading pressures were applied, and leaflet stress, chordal stress, and coaptation results were analyzed.

RESULTS

The average collagen concentration in the normal sheep leaflets was 59.2% (dry weight), 50.6% in the ischemic controls, and 45.8% in the papillary muscle infarct group. Collagen concentration was greatest at the midline and decreased toward the commissures. Increased tissue stiffness resulted in increased leaflet and chordal stresses, as well as reduced coaptation. Decreased stiffness resulted in the opposite. Increased tissue thickness reduced leaflet and chordal stresses, but also reduced coaptation. The combination of increased tissue thickness and decreased stiffness demonstrated the greatest reduction in leaflet and chordal stress, while maintaining normal leaflet coaptation.

CONCLUSIONS

The observed changes may demonstrate an early effort to compensate for increased leaflet stress. Microstructural alterations may demonstrate an early effort to compensate for altered physiologic loading to reduce stress and maintain coaptation. It is crucial in repairing or partially replacing thickened tissue that normal geometry and physiology be restored.

Surface analysis of bileaflet prosthetic heart valve leaflet leading edge

In 1991 and 1992, two patients presented with persistent clinical hemolysis after mitral valve replacement with bileaflet valves, in the absence of paravalvular leaks. When each valve was replaced, the hemolysis disappeared. The first valve was not examined in the laboratory owing to its loss, but it looked normal. The second valve was tested and found to have normal hemodynamics and a normal appearance by light microscopy (LM) and scanning electron microscopy (SEM), but fringe pattern interferometry (FPI) showed its leading leaflet edges to be flatter and rougher than another St. Jude Medical valves (SJMV). This led the authors to collect 17 bileaflet valves (14 SJMV and 3 Carbomedics) for examination of their surface characteristics to see if there was any correlation with hemolysis. All valves were examined by LM, SEM, and FPI. However, only FPI indicated the presence of notable differences in surface roughness and convexity of the leading leaflet edges. Further, convexity of an edge tended to vary inversely with its roughness, and the flat inlet surfaces of most leaflets were consistently less rough than the adjacent edge. The authors' hemolytic valve had one of the flattest and roughest edges of the series. Roughness of the leading edge may contribute to hemolysis by presenting an abrasive surface to the antegrade flow of blood, and by forming the sides of the gap between the leaflets, through which blood is squeezed during closed regurgitation, generating substantial shear forces and causing hemolysis. FPI is a noncontact, sensitive modality, useful in screening pyrolytic carbon surfaces but, unlike other current methods, it is reproducible, does not require modification of the surface, and causes no alteration of the surface texture.

[Pathological observation and immunohistochemistry study of Type I, III, IV collagen in mitral valve and cardiac interstitium of rheumatic disease]

OBJECTIVES

To examine the pathological base of mitral valve and cardiac interstitium of rheumatic disease, and to explore the relationship between Type I, and III, IV collagen in mitral and cardiac interstitium of rheumatic heart disease.

METHODS

HE and ABC method special staining were used to observe the mitral valve and cardiac interstitium pathology in 26 case.

RESULTS

Diffused collagen fibroplasia, hyaline and amyloid degeneration were noted and sometimes associated local necrosis and calcification in myocardial interstitium and in mitral valve. It was a significant pathologic characteristic of rheumatic heart disease. The localization of Type I, III and IV collagen in the valve and myocardiac tissues was studied by ABC method of immunohistochemistry. Significant fibroplasia of collagen Type I and III was found in the valve, cordae tendon and myocardial interstitium of rheumatic heart disease. The composition and secretion of collagen Type I and III were expressed not only in fibroblasts but also in myocardial cells.

CONCLUSIONS

The pathologic foundation of valve and myocardial fibrosis is collagen fibroplasia. The degree of fibroplasia is related to the repeated reaction of chronic rheumatic inflammation.

Histopathologic studies of innervation of normal and prolapsed human mitral valves

We evaluated the distribution of the nerves in valve tissue of humans to clarify the relationship between mitral valve prolapse and autonomic nerve dysfunction. We studied 15 autopsy specimens of normal mitral valve, 10 prolapsed mitral valves, five each of normal tricuspid, aortic, and pulmonary valves, and three prolapsed mitral valves obtained at cardiac surgery. Immunohistochemical studies utilized the avidinbiotin peroxidase complex (ABC) method and several nerve-related antigens: 1) S-100 protein, glial fibrillary acidic protein (GFAP), and neurofilament protein (NFP) as markers of glial and Schwann cells of the nervous system; 2) choline acetyltransferase (ChAT) to identify cholinergic nerve endings; 3) neuropeptide Y (NPY), a neuropeptide that is distributed in accordance with sympathetic nerves; and 4) calcitonin gene-related peptide (CGRP), a neuropeptide that is distributed in accordance with afferent nerves. Distribution of adrenergic nerve fibers was also examined by fluorescence method. Morphology of nerve endings of the normal mitral valve was studied by electron microscopy. In normal valves, distributions of S-100 protein, GFAP, and NFP immunoreactivities were clearly visible along the subendocardial site on the coaptation aspect of the base-to-body portion of each valve, regardless of the kind of valve. In contrast, there was only a scanty distribution of these reactivities on the physiologic coaptation area of the tip. In prolapsed mitral valves, there was no distribution of S-100-positive protein or other nerve-related antigens in areas of the valve with myxomatous degeneration. Distribution of CGRP, ChAT, and NPY immunoreactivities, and adrenergic fluorescence, were the same as those of the nerve-related antigens in both normal and prolapsed mitral valves. Electron microscopic study of the atrial aspect of normal mitral valves revealed numerous small axons with aggregations of small clear vesicles, indicating cholinergic features. The results suggest that the subendocardial site on the atrial aspect at the middle portion of the mitral valve is rich in nerve endings, including the afferent nerves, and that mechanical stimuli from this area caused by abnormal coaptation in mitral valve prolapse may produce an improper circuit in autonomic nerve function between the central and mitral valve nervous systems.

Physicochemical characterization of natural and bioprosthetic heart valve calcific deposits: implications for prevention

This investigation was performed to provide a comprehensive physicochemical characterization of calcific deposits (CDs) that form on human heart valves under various pathological conditions. We examined and characterized CDs associated with aortic stenosis on congenitally bicuspid valves (n = 10), degenerative aortic stenosis on valves with previously normal anatomy (n = 10), and rheumatic aortic (n = 10) and mitral (n = 10) stenosis. Native and deproteinated CDs underwent chemical analysis and structural characterization, whereas deproteinated CDs were measured for thermodynamic solubility. The CDs in valvular heart disease were microcrystalline apatitic products containing substantial amounts of sodium, magnesium, carbonate, fluoride, and organic fraction. The properties of natural heart valve CDs were compared with those of previously measured CDs that form on or in heart valve bioprostheses. Compared with bioprosthetic valve CDs, natural valve CDs have a higher ratio of calcium to phosphorus, higher crystallinity, and lower solubility. These differences indicate that natural heart valve CDs appear to comprise a more mature biomineral. If the formation of mature CDs proceeds through transient stages involving unstable precursors, then the main strategy for prevention of calcific deterioration of bioprosthetic heart valves would be the development of locally applied long-term inhibitors that both (1) suppress nucleation and growth of more soluble precursors and (2) inhibit subsequent augmentation of less soluble CDs.

Penetration of meropenem into heart valve tissue

Thirty-three patients requiring cardiac valve surgery were administered meropenem 1000 mg by a 5 to 10 min iv injection. Samples of blood, cardiac valve and atrial muscle tissue were removed at valvectomy and analysed for meropenem by high performance liquid chromatography (HPLC) with UV detection. The plasma concentrations observed in the samples from these patients were higher than those reported when meropenem 1000 mg was administered to healthy volunteers by 5 min iv injection. No clinical adverse events attributable to meropenem were reported and the single 1000 mg dose was well tolerated. The penetration of meropenem into cardiac muscle and valve tissue was rapid and in excess of that expected solely on the basis of distribution into extracellular fluid. The concentrations achieved in the tissues were in excess of the MICs of the pathogens commonly causing endocarditis.

In situ mitral valve stabilization with glutaraldehyde

Mitral valve repair in the young rheumatic patient carries a high reoperation rate due to progression of the disease. In an attempt to halt or at least slow down this process, the possibility of fixing in situ the valve tissues with glutaraldehyde was explored. Six weanling sheep underwent tanning of their anterior mitral leaflet for two minutes with 0.5% buffered glutaraldehyde. The non-treated posterior mitral leaflet served as control. The animals were sacrificed at varying intervals between 2.5 and 6 months. At sacrifice, Doppler echocardiography and hemodynamic studies were done. The leaflets were subjected to histopathologic examination and calcium and glutaraldehyde contents were estimated. Glutaraldehyde treatment of the anterior leaflet caused thickening of the cusp and chordae associated with partial devitalization of its core tissue, partial loss of endothelium and intense fibrocellular reaction with abundant elastic fibers without altering its functional integrity. It did not induce calcification. There were no detectable levels of glutaraldehyde at explantation. The posterior mitral leaflets were normal. Although the absence of calcification and partial viability of the tissue are encouraging, it does not necessarily follow that this treatment would arrest progression of the underlying disease. This process may have clinical application in the future, but it is not yet recommended.

Immunohistochemical research on the atrial natriuretic factor (ANF) in rat atrioventricular valves

Immunohistochemical research on atrioventricular valves in normotensive rats revealed that valvular myocardiocytes are the seat of synthesis of the atrial natriuretic factor (ANF). The endocardial cells that border the atrial and ventricular surfaces also had granules which were positive for ANF. The ANF which is also synthesized in the valvular myocardiocytes moved towards the cardiac cavity and crossed the endocardial cells in the more distal areas of the valvular edge. At the same time, the ANF was routed into the blood vessels in the areas close to implantation.

Immunohistochemical and pathological characteristics of dystrophic amyloid in surgically excised cardiac valves

One hundred and thirty-six cardiac valves obtained surgically from 124 patients (aged 15-77 years) were examined. Microdeposition of amyloid was present in sclerotic or sclerocalcific lesions of aortic valves in 38 out of 75 (51%) and mitral valves in 21 out of 61 (34%). Amyloid deposition was not significantly related to the age of the patients. An antiserum raised against a low molecular weight protein extracted from amyloid-laden valvular tissues (about 20 g) reacted positively to amyloid in the cardiac valves. It did not react to amyloid deposition containing fibril proteins including light chain related amyloidosis, reactive amyloidosis, systemic senile amyloidosis, isolated atrial amyloidosis, beta-2-microglobulin related amyloidosis and beta protein related amyloidosis. Further, amyloid in the cardiac valves failed to react immunohistochemically to anti-AA, anti-AL, anti-TTR, anti-ANF, anti-beta 2M and anti-beta protein antibodies. These findings suggest that an unknown amyloid protein is involved in the damaged valves.

[Acute mitral insufficiency in osteogenesis imperfecta]

A 56-year-old woman with known osteogenesis imperfecta tarda but no obvious sign of cardiac disease developed increasing dyspnoea, eventually even at rest, with blood-streaked sputum over a period of 10 days. The chest radiograph demonstrated intraalveolar pulmonary oedema. Transthoracic echocardiography revealed as the likely cause of these signs chordal rupture of the anterior leaflet of the mitral valve with mitral regurgitation. After treatment of the cardiac failure with frusemide (up to 500 mg daily intravenously), nitrates and captopril (25 mg daily by mouth) the diagnosis was confirmed by transoesophageal echocardiography. Elective replacement of the mitral and aortic valves was performed 6 months later. Acid mucopolysaccharides were demonstrated histologically in the valvar stroma, a finding consistent with osteogenesis imperfecta. Echocardiography should be performed routinely in connective-tissue disease to reveal any possible cardiovascular involvement.

Differential collagen distribution in the mitral valve and its influence on biomechanical behaviour

Surgical repair of the mitral valve primarily involves endogenous valve tissue, however, the intrinsic mechanical behaviour of the tissue is not well described. To address this issue, porcine mitral valve leaflets were examined histologically and engineering concepts were applied to understand the mechanical behaviour of the layered tissue. Rectangular portions were excised from the anterior and posterior leaflets, either parallel or perpendicular to the annulus, and sections were stained for collagen (Masson's trichrome). The cross sectional layers of the valve (atrialis/spongiosa, fibrosa, and ventricularis) were identified by differences in cellularity and collagen density. The fibrosa is composed of dense collagen, while the atrialis/spongiosa and ventricularis are composed of loose collagen. Layer thicknesses were recorded digitally across the section. These values were averaged within tissue groups to determine changes in layer thickness over the length of the sample and average thickness of each layer. In all tissue groups, the fibrosa was the thickest layer, and the atrialis/spongiosa layer was thicker than the ventricularis layer. The total and fibrosa layer thicknesses of the anterior leaflet were significantly thicker than in the posterior leaflet. Mechanical engineering analysis of the layered structures under tension indicated that the anterior leaflet would be able to support greater tensile loads than the posterior leaflet. The layered arrangement was then examined as a beam in bending, and was shown to decrease the resistance of leaflets to bending, and decrease the overall bending stresses on the leaflet. This type of analysis may be extrapolated to gain insight into changes in function in diseased valves as well.(ABSTRACT TRUNCATED AT 250 WORDS)

Stress/strain characteristics of porcine mitral valve tissue: parallel versus perpendicular collagen orientation

Mitral valve tissue was analyzed in uniaxial tension testing. Rectangular strips were excised from fresh, whole, porcine mitral valve leaflets, with the long axis in the following orientation: perpendicular to the annulus (posterior [PPERP] and anterior [APERP]), parallel to the annulus (posterior [PPAR] and anterior [CAPAR]), and parallel to the annulus and involving chordal insertions (anterior [MAPAR]). Basal and marginal chordae were also tested. These samples were tested in uniaxial tension (INSTRON Model 1000) at deformation rates of 5 and 10 mm/min, the load applied along the long axis of the strip. The specimens were preconditioned by cyclically loading from 0 to 4.0 g for five cycles, and then applying a final 50-g load. Whole excised porcine mitral valves were previously examined by small angle light scattering, polarized light microscopy, and routine histologic examination in order to ascertain the collagen fiber orientation throughout the valve. Groups tested in uniaxial tension with collagen fibers parallel to the applied stress are significantly stiffer than those with perpendicular fibers (p less than 0.001). Collagen fiber density is greater in the chordae than in the leaflets, and a corresponding increase in stiffness is demonstrated. This indicates that the mitral valve tissue behaves as a classic fiber reinforced composite, i.e., increasing mechanical stiffness (modulus) is related to density and direction of fibers. This information can be applied to the design of biosynthetic valve substitutes with a similar fiber reinforced composite structure.

Deposits of crystalline material containing silicon in surgically excised human valves

Ninety-seven surgically excised natural cardiac valves were examined by scanning electron microscopy and x-ray energy spectroscopy to assess the occurrence of crystalline deposits that contain the element silicon. Valves examined included 33 mitral valves, 63 aortic valves, and 1 tricuspid valve. To reduce the possibility of surface contamination, the deep layers of some valves were examined after exposure by fracture of the valve. Crystalline material containing silicon was observed in the deep tissue. Such crystalline material was sometimes entwined within subendothelial fibers. Crystalline deposits that contained silicon were associated with 34 of 97 of these valves (35%). Among the 34 valves that showed silicon, 24 (71%) also showed microdeposits of calcific material. In view of evidence that silicon may participate in the calcification of bone, and is found in the intima of arteries, a role for this element in ectopic calcification of valves may exist.

[Echocardiographic evaluation of mitral valve calcification]

Preoperative assessment of calcifications is important in order to choose the correct surgical approach for mitral valve disease. To test the accuracy of echocardiography (ECHO) in the semiquantitative analysis of mitral valve (MV) calcifications we preoperatively echo-studied 66 patients, who were to undergo MV replacement of rheumatic disease. Echocardiograms were performed using a standardized method, recorded on videotape and analyzed by two independent observers. Areas of calcification were identified as dense conglomerate echoes which were brighter than those of adjacent internal structures. After removal, the MVs were evaluated by means of inspection (I), direct radiography (X-ray) and quantitative calcium extraction--EDTA spectrophotometry--(QCa). In the three methods ECHO, I and X-ray, MV calcifications were graded as absent (group 1), mild (group 2) nodular (group 3) and diffuse (group 4). Using the chi square test, no significant differences were found between the three methods, or between ECHO and X-ray, or between ECHO and I, while I grading was slightly lower than X-ray grading (P less than 0.002). Using variance analysis, no significant differences were found in QCa in the three methods within group 1 and 4, whereas significant differences were present within group 2 (P less than 0.002) and group 3 (P less than 0.001), due to the lower sensitivity of I. On the base of the observed distribution of QCa in the removed MVs, the following QCa values: a) less than 20 mg, b) 20-80 mg, c) greater than 80 mg, were considered as the selection criteria for a) absent or mild, b) nodular and c) diffuse calcifications respectively.(ABSTRACT TRUNCATED AT 250 WORDS)