Microscopic amyloid deposits in the heart valves: a common local complication of chronic damage and scarring

Descriptive study of the clinical and myocardial status of a population with anatomopathological aortic valve amyloidosis

BACKGROUND

Aortic stenosis (AS) and transthyretin (ATTR) cardiac amyloidosis (CA) share the same clinical profiles and cardiac phenotype. Amyloid deposits have been frequently reported in aortic valves of patients with severe AS referred for surgical aortic valve replacement (SAVR). The aim of this study was to determine the clinical and myocardial status of patients with aortic valve amyloidosis after aortic valve surgery.

METHODS AND RESULTS

We performed a retrospective descriptive study of 46 patients who underwent SAVR for severe AS with amyloid deposits upon histological analysis. All patients were screened for cardiac involvement. Amyloid deposits typing was successful in 35 (76%) patients and 28 (80%) were ATTR. Two (4%) had positive bone scintigraphy and among the 5 myocardial biopsies performed during surgery, 80% were positive for ATTR deposits.

CONCLUSION

ATTR is the predominant type in the presence of amyloid deposits on the aortic valve after surgery for severe AS but is only rarely accompanied by cardiac uptake on bone scintigraphy. Early stages of myocardial involvement are frequent and myocardial biopsy is more sensitive for detection of mild amyloid deposits than bone scintigraphy. underdiagnosed by bone scintigraphy.

The contribution of amyloid deposition in the aortic valve to calcification and aortic stenosis

Calcific aortic valve disease (CAVD) and stenosis have a complex pathogenesis, and no therapies are available that can halt or slow their progression. Several studies have shown the presence of apolipoprotein-related amyloid deposits in close proximity to calcified areas in diseased aortic valves. In this Perspective, we explore a possible relationship between amyloid deposits, calcification and the development of aortic valve stenosis. These amyloid deposits might contribute to the amplification of the inflammatory cycle in the aortic valve, including extracellular matrix remodelling and myofibroblast and osteoblast-like cell proliferation. Further investigation in this area is needed to characterize the amyloid deposits associated with CAVD, which could allow the use of antisense oligonucleotides and/or isotype gene therapies for the prevention and/or treatment of CAVD.

Integrative Multi-Omics Analysis in Calcific Aortic Valve Disease Reveals a Link to the Formation of Amyloid-Like Deposits

Calcific aortic valve disease (CAVD) is the most prevalent valvular heart disease in the developed world, yet no pharmacological therapy exists. Here, we hypothesize that the integration of multiple omic data represents an approach towards unveiling novel molecular networks in CAVD. Databases were searched for CAVD omic studies. Differentially expressed molecules from calcified and control samples were retrieved, identifying 32 micro RNAs (miRNA), 596 mRNAs and 80 proteins. Over-representation pathway analysis revealed platelet degranulation and complement/coagulation cascade as dysregulated pathways. Multi-omics integration of overlapping proteome/transcriptome molecules, with the miRNAs, identified a CAVD protein–protein interaction network containing seven seed genes (apolipoprotein A1 (APOA1), hemoglobin subunit β (HBB), transferrin (TF), α-2-macroglobulin (A2M), transforming growth factor β-induced protein (TGFBI), serpin family A member 1 (SERPINA1), lipopolysaccharide binding protein (LBP), inter-α-trypsin inhibitor heavy chain 3 (ITIH3) and immunoglobulin κ constant (IGKC)), four input miRNAs (miR-335-5p, miR-3663-3p, miR-21-5p, miR-93-5p) and two connector genes (amyloid beta precursor protein (APP) and transthyretin (TTR)). In a metabolite–gene–disease network, Alzheimer’s disease exhibited the highest degree of betweenness. To further strengthen the associations based on the multi-omics approach, we validated the presence of APP and TTR in calcified valves from CAVD patients by immunohistochemistry. Our study suggests a novel molecular CAVD network potentially linked to the formation of amyloid-like structures. Further investigations on the associated mechanisms and therapeutic potential of targeting amyloid-like deposits in CAVD may offer significant health benefits.

Unique type of isolated cardiac valvular amyloidosis

Background

Amyloid deposition in heart is a common occurrence in systemic amyloidosis. But localised valvular amyloid deposits are very uncommon. It was only in 1922 that the cases of valvular amyloidosis were reported. Then in 1980, Goffin et al reported another type of valvular amyloidosis, which he called the dystrophic valvular amyloidosis. We report a case of aortic valve amyloidosis which is different from the yet described valvular amyloidosis.

Case presentation

A 72 years old gentleman underwent urgent aortic valve replacement. Intraoperatively, a lesion was found attached to the inferior surface of his bicuspid aortic valve.

Histopathology examination of the valve revealed that the lesion contained amyloid deposits, identified as AL amyloidosis. The serum amyloid A protein (SAP) scan was normal and showed no evidence of systemic amyloidosis. The ECG and echocardiogram were not consistent with cardiac amyloidosis.

Conclusion

Two major types of cardiac amyloidosis have been described in literature: primary-myelomatous type (occurs with systemic amyolidosis), and senile type(s). Recently, a localised cardiac dystrophic valvular amyloidosis has been described. In all previously reported cases, there was a strong association of localised valvular amyloidosis with calcific deposits.

Ours is a unique case which differs from the previously reported cases of localised valvular amyloidosis. In this case, the lesion was not associated with any scar tissue. Also there was no calcific deposit found. This may well be a yet unknown type of isolated valvular amyloidosis.

Amyloid in the cardiovascular system: a review

The cardiovascular system is a common target of amyloidosis. This review presents the current clinical and diagnostic approach to amyloidosis, with the emphasis on cardiovascular involvement. It summarises recent nomenclature, classification, and pathogenesis of amyloidosis. In addition, non-invasive possibilities are discussed, together with endomyocardial biopsies in the diagnosis of cardiac amyloidosis. Finally, recent advances in treatment and prognostic implications are presented.

Rimmed vacuoles with beta-amyloid and ubiquitinated filamentous deposits in the muscles of patients with long-standing denervation (postpoliomyelitis muscular atrophy): similarities with inclusion body myositis

In the chronically denervated muscles of patients with prior paralytic poliomyelitis, there are secondary myopathic features, including endomysial inflammation and rare vacuolated fibers. To assess the frequency and characteristics of the vacuoles and their similarities with those seen in inclusion body myositis (IBM), we examined 58 muscle biopsy specimens from patients with prior paralytic poliomyelitis for (1) the presence of rimmed vacuoles; (2) acid-phosphatase reactivity; (3) Congo-red-positive amyloid deposits; (4) electron microscopy, searching for tubulofilaments; and (5) immunoelectron microscopy, using antibodies against beta-amyloid and ubiquitin. We found vacuolated muscle fibers in 18 of 58 (31%) biopsies, with a mean frequency of 2.06 +/- 0.42 fibers per specimen. The vacuoles contained acid phosphatase-positive material in 6 of the 18 (33.30%) specimens and stained positive for Congo red in five (27.80%). By immunoelectron microscopy, the vacuoles contained 5.17 +/- 0.13 nm fibrils and 14.9 +/- 0.31 nm filaments that immunoreacted with antibodies to beta-amyloid and ubiquitin in a pattern identical to the one seen in IBM. We conclude that vacuolated muscle fibers containing filamentous inclusions positive for amyloid and ubiquitin are not unique to IBM and the other vacuolar myopathies but can also occur in a chronic neurogenic condition, such as postpoliomyelitis. The chronicity of the underlying disease, rather than the cause, may lead to vacuolar formation, amyloid deposition, and accumulation of ubiquitinated filaments.

Neuropathology of cerebral ischemia and hypoxia: recent advances in experimental studies on its pathogenesis

Cerebral hypoxia and ischemia are two of the most common disorders of the central nervous system. The pathomechanism has been a focus of interest in neuroscience for many years not only because of the clinical significance but also because of the peculiar distribution of the lesion (selective vulnerability) depending on the type of injury. This article reviews recent advances in the study of hypoxia-induced tissue injury of the central nervous system.

Amyloid, thrombosis, and acute myocardial infarction in association with a bicuspid aortic valve

A 34 year old man presented with an inferior non-Q-wave myocardial infarction. Echocardiography showed a bicuspid aortic valve with aortic outflow obstruction. Left coronary cusp morphology was normal but the right coronary cusp was grossly distorted and replaced by a mobile echodense mass encroaching upon the aortic valve orifice. The aortic valve was replaced and pathological analysis of the excised valve showed primary amyloid infiltration of the right coronary cusp but a normal left coronary cusp. The mass adherent to the right coronary leaflet had the histological appearances of organised thrombus and this was assumed to be the source of coronary embolism. This is the first reported case of primary valvar amyloid presenting with clinical sequelae and it illustrates the need for careful clinical assessment in young patients presenting with acute ischaemic syndromes.

Dystrophic amyloidosis: a local complication of tissue damage with heterogeneous distribution

Seventeen consecutive patients with dystrophic amyloidosis are reported here (eight Chinese, three Indian, three Iban, two Malay and one Caucasian). Ten were females and seven males, with ages ranging from 12 to 80 years (mean of 48 years). Five instances of dystrophic amyloidosis occurred in areas of tissue damage in the cardiovascular system, including fibrotic cardiac valves and an atheromatous plaque. Three occurred in osteoarthritic joint tissue. Of note were three occurrences in endometriotic cyst walls, four in the fibrotic walls of epidermal cysts, one in a hernial sac and one at the edge of a skin ulcer. All deposits were congophilic and exhibited green-birefringence and permanganate-resistance. Immunohistochemistry did not reveal reactivity for AA protein or immunoglobulin lambda or kappa light-chains. AP protein was detected in 35% of cases. Our results show that, besides the usual sites of osteoarthritic joints and damaged heart valves, dystrophic amyloidosis can complicate other areas of chronic tissue damage and fibrosis such as walls of cysts and ulcers. While the pathogenesis and biochemical nature remain unresolved, immunohistochemistry indicates that neither AA nor AL proteins are present in the deposits, and suggests that a different amyloid protein is involved.

Heart valve involvement in familial amyloidosis with polyneuropathy

Involvement of the heart is common in the various types of amyloidosis. Little attention has, however, been paid to the presence and significance of amyloid in cardiac valves. We examined the heart valves of twelve autopsy cases with familial amyloidosis with polyneuropathy. All leaflets showed more or less abundant amyloid infiltration with significant valvular aortic stenosis due to degenerative calcification in two cases. In familial amyloidosis with polyneuropathy, amyloid deposits are thus invariably present in the valves, but the valvular function is often preserved. Amyloid may, however, produce hemodynamically significant valvular lesions, and the importance of valvular involvement in the various types of amyloidosis may still be underestimated.

Histotopographic evidence that amyloid deposits in sclerocalcific heart valves and other chronic lesions of the cardiovascular system are related to old thrombotic material

Deposition of amyloid in human sclero-calcific heart valves has been reported recently as a localized age-independent and dystrophic form of amyloidosis. Histochemical studies have shown that the deposits are permanganate resistant, contain tryptophan and P component and are immunologically unrelated to any known type of amyloid fibril protein. In this study histological observations from a series of four selected sclerotic heart valves show amyloid deposition in old thrombotic material covering fusing commissures or appositional collagen on the body of the leaflets. Similar cases from extravalvular sites have been added to the series: a partly hyalinized thrombus of the left atrium, a thrombotic aneurysm of the left ventricle, 2 thrombotic atherosclerotic aneurysms of the aorta and popliteal artery respectively, and an encapsulated haematoma of the scalp. The deposits are Congo red positive with typical green dichroism in polarized light, permanganate resistant and contain tryptophan. Electron microscopy of 3 cases displays small fibrils which are typical of amyloid. No patient showed evidence of systemic amyloidosis. The natural history of sclero-calcific valvulopathies and present observations favour the following pathogenesis: first, recurrent thrombotic deposition on thickened and fibrotic endocardium; second, degradation of a coagulation-related protein with beta potential during the aging of the clot with transformation into amyloid fibrils; finally, inclusion of the amyloid in sclerotic replacement tissue.

An investigation of the protein components of amyloid using immunoperoxidase and permanganate methods on tissue sections

Amyloid deposits in tissue from 8 patients with generalized primary amyloidosis, 11 patients with generalized secondary amyloidosis, 11 nasopharyngeal carcinomas, 11 basal cell carcinomas, 4 islet cell tumours, 4 medullary carcinomas of the thyroid and 9 cases of lichen amyloidosis were studied using the indirect immunoperoxidase and peroxidase-antiperoxidase methods with specific antisera against Amyloid A (AA) protein and human immunoglobulin lambda and kappa light chains. The permanganate method of Wright was also applied to tissue sections. Positive staining for AA protein was observed only in secondary amyloidosis. There was excellent correlation between AA positivity and permanganate sensitivity. Positivity for immunoglobulin light chains was not observed in secondary amyloidosis but was noted in 5 (63%) cases of primary amyloidosis and 18-27% of intratumour amyloidosis. Lichen amyloidosis did not stain for AA protein or light chains. It is shown that assessment of the permanganate reaction and AA positivity of amyloid deposits can reliably differentiate secondary from primary amyloidosis and may contribute significantly to selection of patients for appropriate therapy.

Normally and abnormally functioning left-sided porcine bioprosthetic valves after long-term implantation in patients: distinct spectra of histologic and histochemical changes

This morphologic study (X-ray examination of gross specimens, histologic study and histochemical staining) compares two groups of explanted left-sided bioprosthetic valves: group I, 6 valves with normal cusp function and group II, 10 valves with significant dysfunction. Implantation periods ranged from 26 to 79 months. A computerized descriptive statistical method (principal component analysis) is used to analyze the qualitative results. Although qualitatively identical alterations are observed in both groups, the findings in the deep layers of the cusps of severe collagen breakdown, intensive fibrin penetration and various degrees of calcification are restricted to group II. Other findings of interest in both groups include amyloid deposits (four cases) and layering of fusiform host cells on the cusp surface (three cases). The computerized study shows that individuals of one clinical group are morphologically different from those of the other. Mechanical stress may contribute to surface alterations early after implantation, while further collagen breakdown and macrophagic activity result in deep penetration of plasma components and fibrin. Subsequent calcification is likely to be dystrophic rather than metabolic. Colonization of the cuspal surface by endothelial cells after long-term implantation of bioprosthetic valves expresses a new type of relation between host and bioprosthesis.

Amyloid deposits in bioprosthetic cardiac valves after long-term implantation in man. A new localization of amyloidosis

Congo red staining with microscopic examination under polarized light was performed in 30 porcine bioprosthetic cardiac valves and one autologous fascia lata valve explanted from 31 patients in order to detect the presence of amyloid. Microdeposits of amyloid were present in the sewing ring of the fascia lata valve and in 10 porcine bioprostheses, and this finding was confirmed by transmission electron microscopy in 3 porcine bioprostheses. All amyloid-laden porcine valves had been implanted for at least 33 months before removal, and all except two showed dysfunction and/or severe degeneration of cuspal tissue. Statistical analyses failed to establish any correlation between the presence of amyloid and patient-related factors. In a majority of porcine bioprostheses amyloid was permanganate-sensitive and tryptophan-positive. The pathogenesis of this new form of heart valve amyloidosis might consist in penetration of human macrophages in deteriorated bioprosthetic cusps and their interaction with blood-borne amyloid precursors.

Amyloid deposits in aortic and mitral valves. A clinicopathological investigation of material from 100 consecutive heart valve operations

The material from 100 consecutive aortic and mitral valve operations has been studied histologically with particular reference to the presence of amyloid deposits. Sixty seven per cent were positive (aortic 88%, mitral 45%). The simultaneous occurrence of calcification of the valves and amyloid degeneration as well as of calcification and hyalinization was significant. Similarly there was significantly more amyloid in the older age groups, as well as a significant correlation between the degree of hyalinization of the valve and amyloid. Thirty-two patients had previously suffered from rheumatic fever. The heart valves of these patients did not differ histologically from the others, whereas significantly more amyloid was observed in the stenotic mitral valves than in the mitral valves which were insufficient.

Microdeposits of amyloid in sclerocalcific heart valves: a histochemical and immunofluorescence study

Amyloid associated with seven sclerotic and two normal aortic and mitral valves was studied. The sclerotic valve amyloid contained microfibrils with typical random orientation and a fibril width of 9.5-12.5 nm. The amyloid deposits demonstrated permanganate-resistant Congophilia and contained the amino acid tryptophan. Immunofluorescence studies showed P-component in amyloid deposits of 6 of 7 valves, but none of the sclerotic valves contained amyloid fibril proteins of the AL (primary), AA (secondary), AEt (medullary thyroid carcinoma) or ASc1 (senile cardiac) types. Two non-sclerotic valves, removed from a patient with systemic amyloidosis, showed permanganate-sensitive Congophilic amyloid deposits which contained amyloid fibril protein AA.

Localized dystrophic amyloidosis of heart valves

A survey of 152 surgically resected heart valves (90 aortic, 60 mitral, two pulmonic) from a consecutive series of 142 adult patients revealed congophilic, green birefringent, amyloid deposits in 81 valves (59 aortic, 22 mitral) from 77 patients from 41 to 79 years of age. Amyloid was found in 50 (82 per cent) of 61 valves showing degenerative calcific sclerosis and in 31 (53 per cent) of 58 valves showing post-rheumatic sclerosis but in none of 33 valves showing more acute disease processes (myxoid transformation, "stretch lesions," healed bacterial endocarditis). All the amyloidotic valves showed some calcification, and amyloid deposits frequently occurred around the calcified foci. Histochemically, the valvular amyloid was distinguishable from other major forms of amyloid by its largely negative alcian blue and periodic acid-Schiff staining and by its pepsin-resistant iodine staining. The localized, dystrophic nature and unusual histochemical properties of this valvular amyloidosis clearly distinguish it from other forms of cardiac amyloidosis.

Amyloid deposits in heart valves

Localized amyloid deposits were found in 44% of the surgically removed heart valves. They are recognized only in severely destructed valves and the manner of the deposition closely resembles that of aortic intimal amyloid. Although the amyloid fibril protein of the chronically diseased valves is still unknown, it may be neither protein AA nor AL, and another type of amyloid is suggested.

Microscopical atrial amyloidosis in chronic heart disease

Nineteen out of 121 consecutive cardiac biopsies from 107 patients were found to contain amyloid deposits on routine Congo red screening. Seventeen were left atrial appendages removed during mitral valvotomy for chronic rheumatic mitral valve disease while the remaining two were right atrial appendages excised during surgical repair of atrial septal defects. The distribution of amyloid deposits within the atria and their tinctorial characteristics are described. The high prevalence of atrial amyloidosis observed could not be attributed to generalized or senile amyloidosis. The possibility that this is a distinctive localized form of amyloidosis secondary to chronic heart disease is discussed.