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Biomedical subjects

A C Thomas

Publications and source records attributed to A C Thomas.

At least 55 records · Page 3Linked to original sources
PubMed1988

Community study of the causes of "natural" sudden death.

Three hundred and fifty cases of "natural" sudden death within six hours of onset of symptoms in people ranging in age from 18 to 69 years in Wandsworth were studied using a detailed necropsy protocol to determine the cause of death. Sudden death occurred in 28 (8%) Asians and blacks, but because of the small number they were excluded from the study, leaving 322 cases. Ischaemic heart disease accounted for 189 (59%) of the 322 sudden deaths (155 (65%) men; 34 (41%) women) and no proportional increase in instantaneous compared with non-instantaneous sudden death was found. Non-ischaemic cardiac disease was the cause of sudden death in 24 cases (7.5%). Non-cardiac disease included pulmonary emboli, aortic aneurysms, and intracerebral haemorrhage and caused 89 (27.6%) deaths. Alcohol was the cause of nine deaths (2.8%) and in 11 (3.4%) cases (six men and five women) no cause of death was found. This study shows that although ischaemic heart disease is the single largest cause of sudden natural death there are other major causes.

Adult↗
PubMed1988

Implantable defibrillation: eight years clinical experience.

Implantation of the first automatic defibrillator occurred in February 1980. Incorporation of cardioversion capability in 1982 resulted in the AICD automatic implantable cardioverter defibrillator. Between April 1, 1982 and April 15, 1988, 3610 patients in 236 U.S. and 84 international centers received AICD pulse generators. Patient population consisted of 2904 males and 683 females with recurrent ventricular tachycardia and/or fibrillation, mean age 59 yrs. (range 9-96 yrs.). Primary diagnoses reported for the patient group were: coronary artery disease (63.5%), nonischemic cardiomyopathy (12.9%), other (6.4%) and unspecified (17.2%). Mean reported LV ejection fraction was 32.8%. Follow-up averaged 12.2 mo. (range 0-72 mo.). Of 385 deaths, 94 (24%) were sudden. Cumulative percentage survival (+/- S.E.) from sudden cardiac death (SCD) was 98.0 +/- 0.3%, 96.5 +/- 0.5%, 95.2 +/- 0.7%, 93.7 +/- 1.0%, 93.7 +/- 1.0% and 89.7 +/- 4.0% at 12, 24, 36, 48, 60 and 72 months, respectively. Operative mortality (less than or equal to 30 days) was 2.5%. Reported side effects/complications were similar to those of pacemakers. To date, 33% of the patients received spontaneous device countershocks. AICD pulse generator survival from electrical and mechanical failures was 92.8 +/- 0.5%, 88.4 +/- 0.7%, 86.7 +/- 0.8% and 86.4 +/- 0.9% at 12, 18, 24 and 30 mos. Data analysis demonstrates that the AICD has had a significant impact on patient survival from SCD.

Death, Sudden↗
PubMed1988

Cryptogenic tuberculosis as a preventable cause of end-stage renal failure.

A women with a history of urethral stenosis, not causing significant urinary tract obstruction but requiring dilation, presented at the age of 49 with renal failure (creatinine clearance of 16-20 ml/min). Investigations (including pyelography) directed to finding the cause of her renal failure were negative with the exception of renal biopsy which revealed granulomata, one of which showed caseation. Treatment with antituberculous drugs arrested the decline in glomerular filtration rate and was later associated with sustained improvement in renal function. Tuberculosis should always be considered as a possible cause of unexplained renal failure even if the classical pyelographic features of tuberculosis, i.e. calyceal distortion and calcification, are absent. Appropriate treatment may improve renal function and avert the need for renal replacement therapy.

Adult↗
PubMed1987

Physical fitness of blind and sighted children.

Twenty-seven children (age 7-17 years) with varying degrees of blindness but with no other known disorder were assessed for physical fitness. Twenty-seven randomly selected children with normal eyesight were also assessed. Maximum oxygen uptake (VO2max) was measured directly during a progressive exercise test on a treadmill. There was a significant and substantial reduction in VO2max in totally blind children (mean +/- standard deviation 35.0 +/- 7.5 ml X min-1 X kg-1) compared with normal children (45.9 +/- 6.6 ml X min-1 X kg-1). Partially sighted children had a significant but smaller reduction in VO2max. Fitness assessed by a step-test was significantly reduced in the visually impaired children, and skin-fold thickness was also significantly greater in totally blind children. The level of habitual physical activity for each child, as assessed by a questionnaire, correlated with VO2max (r = 0.53, p less than 0.0001). Blind children were significantly less active than normal children, and the difference between mean VO2max for blind and normal children became non-significant when their different activity levels were taken into account. It is concluded that totally blind children are less fit than other children at least partly because of their lower level of habitual activity.

Adolescent↗
PubMed1987

Minimal change glomerulonephritis in the elderly--the role of renal biopsy.

We describe the case histories of three septuagenarians with nephrotic syndrome who would not have been thought likely to have had minimal change disease on clinical grounds. Yet in the three patients all non-sclerosed glomeruli were normal on light microscopy and glomerular immunofluorescence was negative. All three showed a good clinical response to steroids. It is clear from our findings that, in the elderly, clinical criteria are not a reliable guide to renal histology and may lead to a potentially treatable condition, minimal change nephropathy, being overlooked. Because of the high incidence of side effects, a trial of steroids in the elderly is hazardous. From the evidence given we conclude that renal biopsy, in adults with nephrotic syndrome, becomes increasingly useful with advancing age.

Age Factors↗
PubMed1986

Potential errors in the estimation of coronary arterial stenosis from clinical arteriography with reference to the shape of the coronary arterial lumen.

Underestimation of coronary arterial stenosis at clinical arteriography has been explained by inadequate radiological views of crescentic or slit-shaped lumens. Postmortem perfusion-fixation of the coronary arteries at physiological pressures shows that most stenotic lesions result in circular, elliptical, or D-shaped lumens. Crescentic lumens in fully distended vessels are associated only with acute mural thrombus projecting into the lumen or with massive intra-intimal thrombus and plaque fissuring. Elliptical and D-shaped lumens, however, adequately explain the clinically observed phenomenon that some stenotic lesions can be seen only in one x-ray plane and not in another. It is no longer correct to postulate a crescentic or slit-like lumen. Furthermore, not only can elliptical and D-shaped lumens result in underestimation of stenosis, they may also result in serious overestimation. Lumens need only to deviate slightly from being circular for error to be introduced into the estimation of stenosis by currently used methods. The calculation of percentage stenosis from densitometric measurements or from computerised reconstruction of the arterial lumen is, however, more accurate.

Coronary Disease↗
PubMed1986

Morphological characteristics of clinically significant coronary artery stenosis in stable angina.

All segments of clinically significant stenosis in the coronary arteries of 54 men with stable angina were categorised according to the position of the plaques (eccentric or concentric) and the presence or absence of a pool of extracellular lipid. In the group as a whole, stenosis of greater than 50% by diameter was caused by concentric fibrous plaques in 48% of lesions, by concentric lipid plaques in 28%, by eccentric fibrous plaques in 12%, and by eccentric lipid plaques in 12%. In addition, 43 of the 54 patients had one or more stenoses with multiple channels (recanalisation). Eccentric plaques with an arc of normal vessel wall occupying more than 16% of the circumference of the residual lumen were considered to have a vasospastic potential and made up 15% of all lesions with stenosis of greater than 50% by diameter. Forty four per cent of plaques causing stenosis between 30% and 50% by diameter were eccentric and retained a considerable arc of normal media. These lesions were often in series with segments of higher grade stenosis that did not have an arc of normal media. The overall frequency of plaque types gave no indication of the proportions of different plaque types within an individual. In 15% of patients all the plaques causing greater than 50% diameter stenosis were fibrous and in 13% of patients all the plaques were of the lipid type. Most patients had mixtures of all plaque types in varying proportions. Plaques with a large pool of lipid were not found in 33% of patients whereas they formed greater than 90% of the plaques in 9% of patients. No segments of stenosis > 50% by diameter with a vasospastic potential were found in 44% of the patients but one or more such plaques was present in the the remaining 56%. Three patients (6%) each had five separate segments of stenosis with a vasospastic potential. The results indicate that even in a population of men with stable angina in whom diabetes is excluded the distribution of types of atheromatous lesions is very heterogenous.

Aged↗
PubMed1986

Intramyocardial platelet aggregation in patients with unstable angina suffering sudden ischemic cardiac death.

A specific search for intramyocardial platelet aggregates was made in 90 patients who died suddenly of ischemic heart disease. Platelet aggregates in small intramyocardial vessels were found in 27 (30%). There was a significant difference (p less than .05) in the incidence of platelet aggregates in patients with chest pain of recent onset (unstable angina) before death (16/36, 44.4%) and that in those without it (11/54, 20.4%). Multifocal microscopic necrosis with involvement of the full thickness of the ventricular wall, including the subpericardial zone, was significantly more common (p = less than .005) in the patients with platelet emboli (55.6% vs 12.7%). With one exception, aggregates were confined to the segment of myocardium immediately downstream of a major epicardial coronary artery containing an atheromatous plaque that had undergone fissuring and on which mural thrombus had developed. The results support the view that platelet aggregates in the myocardium represent an embolic phenomenon and are a potential cause of unstable angina. The association of myocardial necrosis with such emboli could precipitate sudden death from ventricular fibrillation.

Angina Pectoris↗
PubMed1985

The assessment of cardiac hypertrophy at autopsy.

The total weight of the normal adult human heart as well as that of each ventricle is proportional to body size. Body weight is superior to height as a predictor of total heart and isolated ventricular weights. Ventricular wall thickness is an insensitive means of assessing ventricular hypertrophy. Heart weight is a poor predictor of isolated right ventricular mass but a slightly better predictor of isolated left ventricular mass. The only method of determining the presence or absence of hypertrophy with confidence is to use the Fulton technique for isolated ventricular weights. The use of an arbitrary upper and lower limit, as currently used, for isolated ventricular weights obtained by Fulton's method may, however lead to errors in determining the presence or absence of ventricular hypertrophy.

Adult↗
PubMed1985

Post-mortem investigation and quantification of coronary artery disease.

The controversies that exist amongst pathologists about ischaemic heart disease result in part from the widespread use of non-quantifiable techniques in examining the coronary artery tree. Such techniques are used because it is believed that there is no alternative method which does not involve an inordinate expenditure of time, money and effort. This paper describes procedures involving post-mortem coronary angiography which may be used alone or in combination with histological examination to give an immediate, accurate and permanent record of coronary artery disease or allow a far more detailed quantitative investigation of coronary vasculature.

Angiography↗
PubMed1985

The demonstration of cardiac pathology using perfusion-fixation.

A simple, cheap and reliable method of perfusion-fixation of hearts is described using readily available domestic water fitments and a pump specifically designed for continuous pumping of corrosive fluids. Hearts fixed in this way readily lend themselves to dissection in echocardiographic planes so that strict correlation with clinical echocardiography may be made. Furthermore it is an excellent way to demonstrate functional valve pathology on post-mortem material.

Dissection↗
PubMed1983

The potassium/sodium ratio in the demonstration of sudden ischemic cardiac death: a critical appraisal.

The practical value of measuring the ratio of potassium ion (K+) to sodium ion (Na+) in myocardium as an indicator of early inapparent infarction in sudden cardiac death was assessed using a series of 29 human hearts from selected coroner's autopsies together with experimental material from dogs, including infarcts of 5 min to 4 h duration. Samples for electrolyte analysis were derived from a transverse slice of each heart, taken through both ventricles midway between base and apex, all slices being completely subdivided into a numbered sequence of blocks. Ratios were mapped and compared with macroscopic enzyme staining and histological stains for injured muscle. Detailed examination of coronary arteries was performed on all human cases. Measurement of the K+/Na+ ratio did not detect all human cases of proven acute coronary occlusion and did not unequivocally demonstrate experimental infarcts less than 2 h old. Moreover, all ratios fell with increasing duration of autolysis, emphasizing the need for multiple sampling so that each heart may serve as its own control. As a routine test, therefore, the method is both impracticable and unreliable and as previously used has been subject to misinterpretation.

Adolescent↗
PubMed1981

Has the change to beta-agonists combined with oral theophylline increased cases of fatal asthma?

An apparent increase in young people dying suddenly from acute asthma has been noted in the past 2 years in Auckland. 22 fatal cases were reviewed. Prescribing habits for asthma therapy have been changing in New Zealand, with a considerable increase in the use of oral theophylline drugs, particularly sustained-release preparations, which in many patients have replaced inhaled steroids and cromoglycate. It is suggested that there may be an additive toxicity between theophylline and inhaled beta 2-agonists at high doses which produces cardiac arrest. Also when regular symptomatic treatment with bronchodilators replaces inhaled steroids or cromoglycate the patient's perception of an asthma crisis may be delayed.

Administration, Oral↗
PubMed1980

Secondary carcinoma of left atrium simulating myxoma.

Three cases are presented in which secondary carcinoma in the left atrium mimicked atrial myxoma or infective endocarditis. Constitutional features of weight loss, fever, anaemia, leucocytosis, raised erythrocyte sedimentation rate, and systemic emboli were prominent clinical features. The association of these systemic manifestations with both secondary deposits in the atrium and atrial myxomata may be the result of an immune response to circulating tumour antigens. Mitral stenosis was present in two of the three patients suggesting that left atrial thrombus may provide a site for the seeding of malignant cells.

Adult↗