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Biomedical subjects

W C Roberts

Publications and source records attributed to W C Roberts.

At least 505 records · Page 28Linked to original sources
PubMed1981

Structure of bovine parietal pericardium and of unimplanted Ionescu-Shiley pericardial valvular bioprostheses.

To obtain a basis for the evaluation of postimplantation changes in bioprostheses made of parietal pericardium, we conducted comparative histologic, scanning and transmission electron microscopic studies of the structure of (1) normal bovine parietal pericardium, (2) glutaraldehyde-treated pericardial patches to be used for repair of cardiac defects, and (3) pericardial tissue cusps of unimplanted Ionescu-Shiley valves. Bovine parietal pericardium has three layers: (1) the serosa, or mesothelial cell layer; (2) the fibrosa, formed by diversely oriented, wavy bundles of collagen and by elastic fibers, and (3) the epipericardial connective tissue layer, which is partly continuous with the pericardiosternal ligaments. Pericardial patches and pericardial bioprosthetic cusps differ from normal pericardium by being denuded of mesothelium but they have normal degrees of waviness in their collagen. In Ionescu-Shiley valves, the inflow and outflow surfaces of each cusp correspond to the epipericardial and serosal surfaces of parietal pericardium, respectively. The inflow surfaces have a coarse texture, characterized by large bundles of collagen, and the outflow surfaces have numerous grooves, 10 to 30 mu in width and 20 mu in depth, which probably result from pressure exerted on the cuspidal surfaces by cotton material either during manufacturing or packing of the valves. Comparisons of the structure of bioprosthetic pericardial cusps and porcine aortic valve cusps show that the latter have reduced degrees of collagen waviness and a different layered structure: A layer similar to the spongiosa of aortic valve cusps is not present in pericardium. The functional implications of these observations are discussed in detail.

Animals↗
PubMed1980

Amount of narrowing by atherosclerotic plaque in 44 nonbypassed and 52 bypassed major epicardial coronary arteries in 32 necropsy patients who died within 1 month of aortocoronary bypass grafting.

In 32 necropsy patients who died within 30 days of an aortocoronary bypass operation performed for relief of angina pectoris, the lumens in 42 (95 percent) of 44 nonbypassed and in 52 (100 percent) or 52 bypassed arteries were narrowed 76 to 100 percent in cross-sectional area by atherosclerotic plaque. Of 616 five mm segments of the 44 nonbypassed arteries examined histologically, 292 (47 percent) were narrowed 76 to 100 percent in cross-sectional area by atherosclerotic plaque; of 728 segments examined in the 52 bypassed arteries, 375 (52 percent) were similarly narrowed. Thirty-two (73 percent) of the 44 nonbypassed coronary arteries (in 23 patients) had been judged to be narrowed 50 percent or less in diameter on preoperative coronary angiography, but at necropsy 31 (97 percent) of these arteries were narrowed 76 to 100 percent in cross-sectional area and the other artery was narrowed 51 to 75 percent. Thus, significant amounts of atherosclerotic plaque tend to be present at necropsy in all three major coronary systems of patients with angina pectoris who die early after an aortocoronary bypass operation.

Adult↗
PubMed1980

Frequency and direction of interatrial shunting in valvular pulmonic stenosis with intact ventricular septum and without left ventricular inflow or outflow obstruction. An analysis of 127 patients treated by valvulotomy.

This report summarizes observations in 127 patients who underwent pulmonic valvulotomy for valvular pulmonic stenosis with intact ventricular septum and without obstruction to left ventricular inflow or outflow. Of the 127 patients, 30 (24%) preoperatively by dye dilution curves had shunting at the atrial level: in 19 (63%), the shunt was right-to-left, and in the other 11 (27%), entirely left-to-right. The patients with right-to-left interatrial shunts had severe pulmonic valve stenosis (average peak systolic pressure gradient = 120 +/- 11 mm. Hg) and small (average diameter 1.1 +/- 0.1 cm.) sized defects in the atrial septum (patent foramen ovale). In contrast, the patients with left-to-right shunts had mild to moderate pulmonic valve stenosis (average peak systolic pressure gradient = 60 +/- 5 mm. Hg) and relatively large (average diameter = 2.8 +/- 0.1 cm.) defects in the atrial septum (true atrial septal defect). The patients with right-to-left interatrial shunts had no significant differences in right versus left atrial pressures. The patients with left-to-right interatrial shunts, however, had left atrial pressures significantly greater than right atrial pressures (7 +/- 0.5 vs 5 +/- 0.5, p less than 0.05). No significant differences were found in ventricular end-diastolic pressures.

Adolescent↗
PubMed1980

Histologic and ultrastructural features of normal human parietal pericardium.

Morphologic studies of normal anterior parietal pericardium from seven patients revealed this tissue to be composed of three layers: (1) the serosa, consisting of a surface layer of mesothelial cells and a narrow submesothelial space, (2) the fibrosa, containing variously oriented layers of collagen fibrils and small elastic fibers, and (3) the epipericardial connective tissue layer, containing mainly large coarse bundles of collagen and forming part of the pericardiosternal ligament. Scanning electron microscopic examination is most useful for study of the surface features of pericardial mesothelial cells, which have single cilia and are covered with microvilli. The latter bear friction and increase the surface area for fluid transport. Junctional complexes between adjacent mesothelial cells consist of desmosomes, which reinforce intercellular adhesion and zonulae occludentes, which form permeability barriers. Actin-like filaments (50 A in diameter) are present in microvilli and in immediately subjacent regions of the cells; these filaments mediate changes in cell shape. Intermediate filaments (100 A in diameter) are associated with desmosomes and form bundles in the perinuclear regions; these filaments provide structural support to the cytoplasm.

Adolescent↗
PubMed1980

Congenital hypoplasia of portions of both right and left ventricular myocardial walls. Clinical and necropsy observations in two patients with parchment heart syndrome.

Clinical and morphologic findings are described in two patients with congenital hypoplasia of portions of both right and left ventricular free walls in the absence of associated coronary or valvular heart disease. One, a 61 year old man who had never had clinical evidence of cardiac dysfunction, died suddenly and unexpectedly. The second, a 55 year old woman, died of progressive, eventually intractable congestive heart failure of 29 months' duration. Although at least 22 necropsy patients have previously been reported to have "parchment-like" thinning of portions of the right ventricular free wall, only one patient has previously been described with such thinning of portions of both right and left ventricular free walls. The spectrum of right or right and left ventricular wall congenital hypoplasia is a broad one, with nearly half of described patients dying of congestive heart failure in the 1st year of life and the other half reaching adulthood with or without manifestations of cardiac dysfunction.

Cardiomyopathies↗
PubMed1980

Comparison of amount of myocardial cell disorganization in operatively excised septectomy specimens with amount observed at necropsy in 18 patients with hypertrophic cardiomyopathy.

The extent of cardiac muscle cell disorganization in excised septectomy specimens in 18 patients was compared morphometrically with that observed at necropsy when these patients died after operation. Disorganization was present in all 18 patients at necropsy and was extensive (5 percent or greater) in 16 of the 18. In contrast, there was no disorganization in the operative specimens of three patients and only a trivial amount (less than 1 percent) in five others. Disorganization extensive enough (5 percent or greater) to suggest hypertrophic cardiomyopathy was present in the operative specimens of only 6 of the 18 patients. The mean (+/- standard error of the mean) area of disorganization at necropsy was 20 +/- 3 percent compared with 7 +/- 2 percent in the operative specimens (p less than 0.001). Thus, histologic examination of operatively excised septectomy specimens is of limited value in confirming the diagnosis of hypertrophic cardiomyopathy.

Adult↗
PubMed1980

Hemochromatosis heart disease: an unemphasized cause of potentially reversible restrictive cardiomyopathy.

Cardiac involvement in hemochromatosis typically results in congestive cardiomyopathy; a restrictive cardiomyopathy due to hemochromatosis is distinctly rare. A restrictive cardiomyopathy, which developed in the patient described in this report, was due to hemochromatosis which mimicked constrictive pericarditis clinically, echocardiographically and hemodynamically, and resulted in a thoracotomy for attempted surgical therapy. The fact that hemochromatosis represents the only cause of a restrictive cardiomyopathy that is potentially reversible by medical therapy makes early recognition of hemochromatosis heart disease important.

Cardiomyopathies↗
PubMed1980

Disseminated Petriellidium boydii and pacemaker endocarditis.

Clinical and morphologic findings are described in a 62 year old woman with "mixed connective tissue disease" who received corticosteroid therapy, and in whom disseminated and fatal Petriellidium boydii infection with right-sided endocarditis developed. The patient was a gardener. The organism is ubiquitous in soil in many part of the United States; therefore, it is likely that the infection was introduced by this means. Endocarditis due to P. boydii has not been reported previously. In the patient described, massive vegetations nearly obliterated the tricuspid valve orifice, encasing a pacemaker catheter which had been inserted eight years earlier. Although never previously isolated from blood cultures, P. boydii was isolated from 11 consecutive blood cultures. P. boydii is a true fungus and has only recently been appreciated as an opportunistic pathogen in a compromised host.

Endocarditis↗