Biomedical subjects

M D Silver

Publications and source records attributed to M D Silver.

At least 19 recordsLinked to original sources

PubMed2001

Myocardial contraction bands. Definition, quantification and significance in forensic pathology.

Pathological contraction bands affecting myocardial cells are observed in many different human conditions and in different experimental models. Their morphology was defined long ago but we need to understand the pathogenesis and functional meaning. A distinction between different histological forms of contraction bands and their quantification in a large spectrum of human diseases (262 cases) and a normal population sample where death was due to various types of accidental death (170 cases) produced the following conclusions: 1) The term "contraction band necrosis", as used presently, is ambiguous and should be reserved for a specific morpho-functional entity induced experimentally by intravenous catecholamine infusion and seen in equivalent human cases with pheochromocytoma. 2) In human pathology it may represent a sign of adrenergic stress linked with malignant arrhythmia/ventricular fibrillation. 3) Beyond a histological threshold of 37+/-7 foci and 322+/-99 myocells/100 mm2, the lesion may indicate sympathetic overdrive in the natural history of a disease and associated arrhythmogenic supersensitivity. 4) The detection of few pathological contraction bands in normal subjects in some types of accidental death correlates with the survival time, suggesting an agonal adrenergic stimulation to promote the cardiac pump.

Acquired Immunodeficiency Syndrome↗

PubMed2000

A method for including redundant data in computed tomography.

A method for including redundant data in fan-beam computed tomography (CT) is presented. It is a natural extension of the Parker [Med. Phys. 9, 254-257 (1982)] short-scan approach applied to divergent fan-beam (or cone-beam) data when the data set covers between the minimally complete set of 180 degrees plus fan angle and 360 degrees. A virtual fan angle is introduced whose value is the difference between the angular range of the data collected and 180 degrees. Parker-weights are then applied as if the field-of-view is spanned by the virtual fan angle.

Image Processing, Computer-Assisted↗

PubMed2000

Fatal myocardial embolus after myectomy.

Coronary embolism is an infrequent phenomenon. A 56-year-old man with hypertrophic obstructive cardiomyopathy and severe mitral regurgitation who underwent left ventricular septal myectomy and mitral valve annular repair is presented. The patient had a cardiac arrest 36 h after surgery. Cardiac standstill, tamponade and a left ventricular rupture were noted when the chest was opened during attempted resuscitation. Autopsy revealed an occlusive embolus of myocardium in the proximal left anterior descending coronary artery. It showed pathological features of hypertrophic cardiomyopathy. There was an extensive acute transmural anteroseptal left ventricular myocardial infarction with rupture of the anterior free wall. Embolism of myocardium - to the coronary arteries, the systemic circulation or the pulmonary circulation - is a rare event, with only nine other cases reported in the literature in the past 30 years. This is the first reported case of myocardial embolus to a coronary artery in a patient with hypertrophic obstructive cardiomyopathy following septal myectomy.

Cardiomyopathy, Hypertrophic↗

PubMed1999

Morphologic findings in explanted Hancock II porcine bioprostheses.

BACKGROUND AND AIM OF THE STUDY: Heart valve substitutes have been in use for over 30 years. Bioprosthetic heart valves have many advantages, but unfortunately suffer tissue degeneration and calcification. Many approaches, such as antimineralization treatment to prevent or delay these changes, have been tried. We present the morphologic findings from a series of Hancock II (antimineralization-treated) porcine bioprostheses. METHODS: Forty-five Hancock II porcine valve bioprostheses (16 mitral, 29 aortic) surgically explanted between March 1991 and December 1995 at the Toronto Hospital were analyzed for morphologic findings and causes of failure. The prostheses were implanted in 36 adults (mean age 55+/-14.7 years, range: 27 to 75 years) and had been in place between one month and 11 years (mean 5.1+/-3.3 years). RESULTS: Structural valve deterioration (SVD) characterized by tissue degeneration, calcification, cusp tears and increased stiffness, was the single most significant finding and cause of failure, affecting 56% of valves. Some degree of calcification was seen in 55% of prostheses, with severe calcification (grade 3 or 4) in 18%. Aortic bioprostheses showed more severe and earlier calcification than mitral ones (p = 0.03). Compared with the standard Hancock valve, the low incidence of significant calcification suggests a beneficial protective effect of antimineralization treatment. Severe pannus (grade 3 or 4) was seen in 60% of these prostheses. The pattern of pannus growth differs between mitral and aortic sites; mitral prostheses showed pannus on the flow and non-flow surfaces, often associated with cusp tears, mitral regurgitation and mitral leaflet preservation. A similar degree of pannus on aortic prostheses was invariably present on the flow surface and extended onto the valve cusps, leading to changes in the orifice which may cause clinical aortic stenosis. Infective endocarditis was seen in 15 prostheses (five mitral, 10 aortic) from 11 patients, and comprised the second most important cause of prosthesis failure. The risk of recurrent endocarditis was particularly high in patients who had infective endocarditis before valve replacement, even at five and six years post implantation. CONCLUSIONS: SVD is the major finding in explanted Hancock II bioprostheses and is associated with cusp tears and calcification. The incidence of tissue calcification appears lower at the mitral site. These findings suggest that the antimineralization treatment had some beneficial effect. Pannus associated with prosthesis dysfunction at the mitral sites is a prominent finding and on the non-flow surface may be related to the native mitral valve-conserving procedure.

Adult↗

PubMed1999

Left ventricular involvement in right ventricular dysplasia/cardiomyopathy.

OBJECTIVE: To characterize pathological features of left ventricular (LV) involvement in right ventricular dysplasia/cardiomyopathy (RVD/C). DESIGN: Retrospective morphological case study. SETTING: Two referral-based university medical centres. MATERIALS: Seventeen hearts were studied: 15 from sudden cardiac deaths outside hospital and two explanted hearts, one removed for intractable arrhythmias and the other for right-sided heart failure. The subjects (three female) were aged 16 to 60 years. MAIN RESULTS: All had typical right ventricular features of RVD/C and morphological evidence of LV wall involvement, seven with microscopic changes only. Of 10 hearts with gross and microscopic lesions, nine had large or laminar segments involved. The LV free wall was affected in all cases and the ventricular septum (VS) in 15. Sixteen hearts were hypertrophied. In involved areas, the LV or VS walls were of 'normal' thickness or slightly thinned. Five histological patterns of involvement were recognized, of which four were found in the LV. More severe LV involvement was seen in the hearts of older patients. Complete transmural fatty replacement of the myocardium was not observed, nor were the LVs aneurysmal. Minimal or mild focal aggregates of inflammatory cells were seen in nine hearts and moderate inflammatory changes in two. Inflammation was usually associated with myocyte atrophy and only rarely with myonecrosis. CONCLUSIONS: This study suggests that patients with RVD/C who live long enough will likely have LV free wall involvement with frequent VS involvement. Pathologists may miss LV involvement on gross examination. It should be sought diligently in patients dying of the condition or receiving transplants for heart failure. Appropriate histological sections from both free wall and septum must be examined.

Adolescent↗

PubMed1999

Endometriosis of the pelvis presenting as hip pain. A case report.

Endometriosis is a disorder resulting from the presence of actively growing and functioning endometrial tissue in aberrant sites outside the uterus. Ectopic implantation of the endometrium can be located throughout the pelvic cavity. Depending on the location of the endometriosis, it can mimic common musculoskeletal problems, especially in young women who are menstruating. A young woman presented to an orthopaedic specialist with bilateral hip pain for the last several years. Magnetic resonance imaging subsequently was performed on both hips and showed evidence of bilateral intrapelvic endometriosis adjacent to both acetabula. The patient was seen by her gynecologist, who prescribed cyclic hormonal suppressive therapy. On followup visit to the orthopaedist, the patient's symptoms had resolved completely.

Adult↗

PubMed1998

High-helical-pitch, cone-beam computed tomography.

The object of a helical, cone-beam computed tomography, HCBCT, system is faster scan times for the volume of interest for a patient. The maximum helical-pitch that still produces good quality images limits the reduction in scan time. Although this is a three-dimensional problem, an extension of the completeness condition for a two-dimensional fan-beam reconstruction method serves as a guide to estimate the maximum helical-pitch. In HCBCT, each pixel in an arbitrary image slice is irradiated over a different range of gantry rotation angles. This leads to the idea of a different, or inconsistent, range of backprojection angles for each pixel in order to increase the helical-pitch while satisfying the completeness condition. Using inconsistent backprojection, the normalized helical-pitch ratio increases from 0.90 to 1.40 (for a source radius of 600 mm and field of view of 500 mm), where the normalized helical-pitch ratio is the linear advance of the patient couch per gantry revolution to the full axial height of the area detector (as projected at the isocentre).

Algorithms↗

PubMed1997

Sudden and unexpected death in clinically 'silent' Chagas' disease. A hypothesis.

BACKGROUND: Chagas' heart disease presents an interesting model of cardiac autonomic nerve dysfunction associated with morphologic lesions. A lack of quantitative evaluation of the latter suggested this study in which hearts from 34 subjects who were serum-positive for Chagas' disease but had no clinical evidence of it and who died suddenly and unexpectedly, out-of-hospital, were examined. METHODS AND RESULTS: By systematic myocardial sampling the histologic area was measured to establish: (a) the number of focal lymphocytic infiltrates x 100 mm2 and average number of lymphocytes per focus; (b) number of foci of, and myocells with, coagulative myocytolysis (contraction band necrosis) x 100 mm2; and (c) the percentage of substitutive myocardial fibrosis. In all cases findings were: (a) intermyocellular lymphocytic infiltrates (6 +/- 6 foci x 100 mm2); (b) coagulative myocytolysis (3 +/- 5 foci and 26 +/- 56 myocells x 100 mm2). CONCLUSIONS: In all 34 subjects quantitative analysis showed extensive lymphocytic infiltrates and myocardial damage typical of catecholamine cardiotoxicity. These two acute or active histological changes may explain their sudden demise produced by focal denervation with regional asynergy and consequent compensatory adrenergic stimulus with myotoxicity and malignant arrhythmia.

Acquired Immunodeficiency Syndrome↗

PubMed1997

Lipomatous metaplasia in left ventricular scar.

BACKGROUND AND OBJECTIVE: Substitution of interstitial tissue by fat may be observed in the right ventricle of hearts but is less common in the left ventricle. Fat was noted in myocardial scars of patients undergoing heart transplantation, prompting this retrospective study to determine the frequency of left ventricular myocardial scar being replaced by fat and its significance METHODS AND RESULTS: The left and right ventricles and coronary arteries were sampled systematically and lesions quantified histologically in 97 normal subjects dying accidentally; 116 consecutive failing hearts excised at transplantation from patients with ischemic heart disease, idiopathic dilated cardiomyopathy or chronic valvulopathy; and 34 autopsy hearts of apparently normal subjects with "silent' Chagas' heart disease who died suddenly and unexpectedly. Twenty-two left ventricular aneurysmectomy specimens from ischemic patients with heart failure were also studied. Among excised hearts lipomatous metaplasia of myocardial scar was observed in 68% of ischemic heart disease, in 37% of chronic valvulopathy and in 26% of idiopathic dilated cardiomyopathy patients; it was seen in 15% of Chagasic patients and in 55% of aneurysm walls. CONCLUSIONS: Lipomatous metaplasia of scar is often associated with severe heart failure and is more frequent and extensive in ischemic heart disease. Transformation of a compact scar into compressible and "sliding' adipose tissue may worsen ventricular wall function, thus facilitating and/or aggravating aneurysm formation. This phenomenon must be considered in the evaluation of myocardial repair, cardiac imaging of viable myocardium, quantitative morphology of autopsy specimens, and qualitative and quantitative biochemical analysis of myocardial tissue.

Adipose Tissue↗

PubMed1997

Cardiac metastasis from primary cervical squamous cell carcinoma: three case reports and a review of the literature.

Clinically evident cardiac metastases from malignant neoplasms are uncommon, occurring most commonly in association with lung and breast carcinoma, lymphoma, leukemia and melanoma. The vast majority, over 90%, present with pericardial involvement. Squamous cell carcinomas of the cervix rarely produce cardiac metastases, with endomyocardia metastases being particularly rare. Three patients are reported who presented with primary squamous cell carcinoma of the cervix and developed this pattern of metastasis, one of whom was diagnosed at endomyocardial biopsy and the other two at autopsy. The paucity of such cases in the literature emphasizes the uniqueness of this phenomenon.

Adult↗

PubMed1997

Type and extent of myocardial injury related to brain damage and its significance in heart transplantation: a morphometric study.

BACKGROUND: Focal myocardial necrosis reported in patients who died of brain lesions and in donor hearts soon after insertion has been attributed to catecholamine-related injury induced before operation, or in the perioperative period. Interpretation of the morphofunctional type of myocardial injury observed and its quantification may help understand both its pathophysiology and clinical relevance. METHODS: In 27 patients without heart disease who died of intracranial brain hemorrhage after berry aneurysm rupture, terminal clinical signs were correlated with the presence of absence of myocardial injury. All hearts were systematically examined, and the total histologic area was measured in square millimeters, with both the number of foci and myocardial cells showing necrosis, normalized to 100 mm2. Forty-five cases of fatal head trauma (26 "instantaneous" and 19 "rapid" deaths) in normal subjects and 38 cases of acquired immunodeficiency syndrome with (14 cases) or without (24 cases) severe brain damage were used as control subjects. RESULTS: Contraction band necrosis was the only form of myocardial necrosis found in 89% of patients with acute brain hemorrhage. Its extent was 26 +/- 34 foci and 67 +/- 104 necrotic myocardial cells x 100 mm2. In patients with acquired immunodeficiency syndrome, its frequency was 58% in those without and 78.5% with severe brain lesions, with foci and myocardial cell values of 1 +/- 1.5 and 10 +/- 22 and 7 +/- 16 and 17 +/- 32, respectively. In head trauma cases with instantaneous death, the frequency was 4% (one case only with foci 0.5 and myocardial cells 35), whereas with a rapid death it was 40% (foci 12 +/- 18 and myocardial cells 21 +/- 33). CONCLUSIONS: The observed myocardial injury was present in all groups examined, being maximal in patients with intracranial brain hemorrhage with longer survival and minimal in patients with head trauma who died instantaneously. In this setting, this lesion is typical of catecholamine myotoxicity and may express a sympathetic overstimulation either in the agonal period and independent of therapy or be caused by brain injury, especially intracranial brain hemorrhage. However, the extent of myocardial injury observed was minimal and should not jeopardize cardiac function if hearts from such subjects are transplanted.

AIDS Dementia Complex↗

PubMed1995

The pattern of desmin filaments in myocardial disarray.

"Myofiber disarray" defines a nonparallel arrangement of cardiac myocytes. The presence of a sufficient quantity of myocardial fibers showing this change is considered to be a specific histological feature of hypertrophic cardiomyopathy (HCM). However, small zones of myofiber disarray are found in both cardiac hypertrophy and other pathological conditions. Recently, we demonstrated an altered pattern of desmin intermediate filaments in disarrayed myofibers from specimens of HCM. To test the hypothesis that desmin alterations might be specific for cardiomyopathy, we performed an immunohistochemical study on myocardial surgical samples from 11 patients with HCM and from 12 patients with tetralogy of Fallot (toF) on 14 endomyocardial biopsy specimens (EMBs) from transplant recipients with myofiber disarray surrounding areas of scarring (previous biopsy site) and on specimens of four autoptic hearts with severe acquired left ventricular hypertrophy. Disarrayed myofibers from all specimens of HCM showed the following abnormalities in the pattern of desmin intermediate filament distribution: (1) decrease or loss of labeling of intercalated discs and Z bands, (2) longitudinal arrangement of desmin intermediate filaments, and (3) intense, granular staining of several myocytes. This spectrum of desmin alterations was never observed in disarrayed myofibers in specimens of toF or acquired myocardial hypertrophy or in EMBs. Altered distribution of desmin intermediate filaments seems to be specific to myofiber disarray in HCM and it may play a role in the altered myocyte arrangement in HCM.

Adult↗

PubMed1995

Atheroembolism in an endomyocardial biopsy from a cardiac transplant recipient after coronary angioplasty.

A case of a coronary atheroembolism after coronary angioplasty was detected by routine myocardial biopsy six years after cardiac transplant. The patient had had three balloon angioplasties within a five week interval for symptomatic accelerated coronary artery disease. Histological examination clearly identified atheromatous debris in a small intramyocardial artery with a secondary inflammatory response. This complication of angioplasty has been identified at necropsy in association with new myocardial infarction. It is unusual to identify this complication in a survivor, and in a case in which there was no clinical evidence of myocardial infarction. Myocardial biopsy samples a relatively small amount of myocardium, and this case suggests that coronary atheroembolism may not be an uncommon complication of angioplasty.

Angioplasty, Balloon, Coronary↗

PubMed1995

Role of stress concentration in the pathogenesis of cardiac rupture following acute myocardial infarction.

OBJECTIVE: To study the cause of myocardial rupture and its related complications using a computer-assisted model of left ventricular (LV) function following acute myocardial infarction. DESIGN: A model previously described by other authors was modified. The LV was portrayed as a three-layered ellipsoid at end-diastolic volume (135 mL). The aspect ratio of the ellipsoid's semi-minor: semi-major axis was 0.6. The apical middle layer was infarcted with an angle of damage of 40%, the infarcted layer being 81.8% of total LV wall thickness. A one-half symmetry condition generated an axisymmetrical, linear, elastic finite element model with 1056 first-order elements and 1127 nodes. The endocardial surface was subjected to static internal pressure, modelling the instant of end-isovolumetric contraction. Noninfarcted myocardium was assumed to be variably stiffer than infarcted muscle. A simple orthotropic model was used to approximate the directional characteristics of muscle layers. RESULTS: Maximum von Mises stresses were found on the endocardial surface near the centre and edge of the angle of damage, the latter generally observed as the site of myocardial rupture. Static stress concentration factors were computed for the isotropic and orthotropic cases. The directional characteristics of the myocardium appeared to be protective. CONCLUSIONS: A more complete pathogenic model for myocardial rupture following acute infarction is stress concentration --> endocardial tear --> dissecting hemorrhage. Marked deformation is predicted in the endocardial surface within the angle of damage, consistent with the correlation between acute myocardial infarction and LV aneurysm formation.

Animals↗

PubMed1995