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Biomedical subjects

M D Silver

Publications and source records attributed to M D Silver.

At least 91 records · Page 5Linked to original sources
PubMed1977

Basement membranes of small cardiac vessels in patients with diabetes and myxoedema: preliminary observations.

Ultrastructural observations on the basement membranes of small vessels from hearts of patients with diabetes, myxoedema and neither disease collected post mortem, reveal that the membranes of those with diabetes are nearly three times as thick as those in normal hearts (P less than 0.001), while in patients with myxoedema they are twice normal thickness (P less than 0.001). A significant difference was demonstrated between the thickness of the basement membrane in patients with diabetes and those with myxoedema (P less than 0.001).

Adult↗
PubMed1976

Idiopathic prolapsed mitral leaflet syndrome. Angiographic-clinical correlations.

Angiographic clinical correlations were made in 59 patients with prolapsed mitral leaflet syndrome. Eight had nonejection systolic clicks (group I), 20 had early, mid or late systolic murmurs with or without a systolic click (group II), and 31 had pansystolic murmurs (group III). Isolated prolapse of posterior leaflet (PL) scallops occurred in 42 and 17 had combined leaflet prolapse. The study demonstrated the following: (I) Group II patients usually had isolated PL prolapse with a predominant biscallop involvement while a high incidence of triple scallop prolapse and combined mitral leaflet prolapse occurred in group III. (II) Severe mitral regurgitation and a greater incidence of atrial fibrillation were seen in patients with triscallop prolapse and combined mitral leaflet prolapse. Mitral regurgitation was milder in patients with single and biscallop prolapse and, when severe, was associated with ruptured chordae. (III) ST-T wave abnormalities in the inferior leads were most frequent in patients with isolated PL prolapse. (IV) Systolic and diastolic asynergy occurred in 41 patients, most frequently in group II but also relatively frequently in group III (19 of 31). Segmental anterior dysfunction with normal ejection fraction was found in 18 patients, of whom 13 had early anterior wall relaxation. (V) Patients without asynergy were slightly older than those with it. More in the former group had severe mitral regurgitation and were clinically disabled from it.

Angiography↗
PubMed1976

Aortocoronary bypass graft in dogs: late histological changes.

Late histological changes occurring in aortocoronary bypass vein grafts were studied by lignt and electron microscopy in three dogs killed one, two and three years after grafting. The changes consisted of intimal thickening due to a proliferation of modified smooth muscle cells (myointimal hyperplasia) and replacement of most of the medial smooth muscle by fibrocytes. Serial angiography in the dogs did not reveal progression of the intimal thickening after one month.

Animals↗
PubMed1975

Familial atrioventricular heart block; an autosomal dominant trait.

A family of 28 individuals spanning four generations was investigated because of a finding of complete heart block in five members and the existence of a low degree of atrioventricular (A-V) heart block in a sixth member. The disorder was characterized by 1) adult onset in all, 2) complete A-V heart block in five and first degree A-V heart block in one, 3) sinus bradycardia in three, 4) atrial fibrillation in five, 5) abnormal QRS complex in five, 6) ventricular tachycardia in three, 7) left ventricular enlargement in all, and 8) mitral insufficiency in five. Proximal location of the A-V heart block was suggested by the fact that atropine caused acceleration of the ventricular rate and by the presence of a His bundle potential preceding the QRS complexes. Involvement of the distal conducting system was indicated by the widened QRS complex and a prolonged H-V interval. Pathologic examination in one case showed extensive sinus node fibrosis and interruption of the A-V node-His bundle connection. This disorder is probably due to an autosomal dominant trait.

Adult↗
PubMed1975

Incomplete rupture of the heart with diverticulum formation.

Two diverticula of the heart that caused no perceptible bulge in the cardiac outline were found at necropsy amongst 197 hearts from patients who had had myocardial infarcts. They lay within the wall of the left ventricle communicating with the left ventricular lumen by a small orifice, had mural thrombus in their lumens, were lined by connective tissue and surrounded by a healing or healed infarct. The lesions resulted from an incomplete rupture of the heart caused by the arrest of a haemorrhagic dissection en route from endocardial to epicardial surfaces through the infarcted ventricular wall. Resorption and organization occurred and a diverticulum formed. The distinct morphology of the diverticulum permits its differentiation from both a left ventricular aneurysm and a pseudoaneurysm.

Aged↗
PubMed1975

A key to identify heart valve prostheses.

A system for the identification of heart valve prostheses has been developed. A series of observations is made on the structure of a prosthesis. Following each the most appropriate choice of two or three alternative findings is made. One is then directed to the next observation until a genus of prostheses is found with structural characteristics like the unknown one. Positive identification is aided by a brief description of each prosthesis in the genus.

Heart Valve Diseases↗
PubMed1975

Ischemic contracture of the left ventricle. Production and prevention.

Ischemic contracture of the left ventricle ("stone heart") is a recognized complication of prolonged periods of interruption of the coronary circulation during open-heart surgery. We have examined the effects of moderate hypothermia (28 degrees C.) and preoperative beta-adrenergic blockade (propranolol, 0.5 mg. per kilogram; 1.0 mg. per kilogram) on contracture development during ischemic arrest of the heart. Four groups of 8 dogs each were placed on total cardiopulmonary bypass, and ischemic arrest of the heart was produced by cross-clamping the ascending aorta and venting the left ventricle. Intramyocardial carbon dioxide tension was continuously monitored by mass spectrometry. When anaerobic energy production ceased, as indicated by a final plateau in the intramyocardial carbon dioxide accumulation curve, the ischemic arrest was terminated and the contractile state of the heart observed. These results are given in the text. We conclude that beta-adrenergic blockade delays, but does not prevent, the onset of ischemic contracture of the left ventricle under normothermic conditions. Moderate hypothermia appears to prevent this complication completely.

Animals↗
PubMed1975

Cardiomegaly in chronic anemia in ratsman experimental study including ultrastructural, histometric, and stereologic observations.

Postweanling rats maintained on a milk-sugar diet develop a sideropenic anemia, the hemoglobin values falling to less than 30 per cent within 8 to 10 weeks. In that period the heart weight increases by more than 3 times, both ventricles enlarging proportionately. As in other forms of cardiac hypertrophy, a progressive increase in the numbers of connective tissue cells occurs. Ultrastructural and stereologic studies show an appreciable proliferation of the mitochondrial mass in myocardial cells, the mitochondrial fractional volume increasing from a normal of 0.38 to 0.48 per unit cell volume. This quantitative increase is accompanied by a progressive deterioration of the internal cristal structure and the appearance of abnormal, degenerating, and necrotic forms of mitochondria as congestive cardiac failure develops. Myofibrils remain normal. The heart of an anemic rat subjected to an additional workload produced by subdiaphragmatic aortic constriction shows an earlier deterioration of the mitochondrial ultrastructure and stereologic profiles. However, it does not become as large as the heart of the purely anemic animal. In anemic animals with an increased workload, the myofibrillar fractional volume increases from a normal of 0.52 to 0.57 per unit cell volume initially. The active sarcomerogenesis is achieved by Z-band proliferation, which was not observed in the heart of the purely anemic animal. These findings provide a structural basis for the functional and biochemical cardiac deterioration observed in the cardiomegaly induced by chronic anemia.

Anemia↗
PubMed1974

The late results of cardiac valve replacement using autologous fascia lata.

Over an eight-month period beginning in November 1969, 53 patients received 63 fascia lata heart valves at the Toronto General Hospital. The late results of this form of valve substitution are reviewed. The fascia used to fashion the tricuspid valve underwent progressive thickening and contracture and this process caused failure of the prosthesis within months of insertion. The mitral fascial prosthesis failed in a similar manner although the process took longer. The aortic fascia lata valve, however, has not shown progressive thickening after 3(1/2) years and it has so far retained its functional integrity. Indeed, we have been impressed by the excellent clinical results and absence of complications such as thromboembolism although anticoagulation has not been used. We therefore consider that fascia lata valves offer a suitable alternative to other forms of aortic valve substitution, but are unsatisfactory for tricuspid or mitral valve replacement.

Adult↗