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Biomedical subjects

M E Thompson

Publications and source records attributed to M E Thompson.

120 records · Page 7Linked to original sources
PubMed1970

Left atrial booster function in valvular heart disease.

This study was designed to assess atrial booster pump action in valvular heart disease and to dissect booster pump from reservoir-conduit functions. In five patients with aortic stenosis and six with mitral stenosis, sequential atrioventricular (A-V) pacing was instituted during the course of diagnostic cardiac catheterization. Continuous recording of valvular gradient allowed estimation of flow for each cardiac cycle by transposition of the Gorlin formula. Left ventricular ejection time and left ventricular stroke work in aortic stenosis or left ventricular mean systolic pressure in mitral stenosis were also determined. Control observations were recorded during sequential A-V pacing with well-timed atrial systole. Cardiac cycles were then produced with no atrial contraction but undisturbed atrial reservoir function by intermittently interrupting the atrial pacing stimulus during sequential A-V pacing. This intervention significantly reduced valvular gradient, flow, left ventricular ejection time, and left ventricular mean systolic pressure or stroke work. Cardiac cycles were then produced with atrial booster action eliminated by instituting synchronous A-V pacing. The resultant simultaneous contraction of the atrium and ventricle not only eliminated effective atrial systole but also placed atrial systole during the normal period of atrial reservoir function. This also significantly reduced all the hemodynamic measurements. However, comparison of the magnitude of change from these two different pacing interventions showed no greater impairment of hemodynamic state when both booster pump action and reservoir function were impaired than when booster pump action alone was impaired. The study confirms the potential benefit of well placed atrial booster pump action in valvular heart disease in man.

Adolescent↗
PubMedDate not supplied

The quantitative evaluation of risks: unresolved problems.

Various generators of risk which are believed to be important, namely unhealthy diet, hazardous occupations, smoking, poverty, radiation and chance of war are considered. The considerations which are relevant for policy in risk evaluation are taken to be the magnitude of the risk, the strength of the evidence that the risk is real, the size of the population at risk and the ease of modification of a behaviour involving risk. Various measures for judging risk are outlined, including mortality rates, relative mortality rates, morbidity measures, and more extensively the analysis of "costs and benefits". The importance of longitudinal studies is stressed. A theoretical framework is presented to describe formally how risk can be quantified. This is followed by a discussion of risks associated with specific hazardous activities. It is suggested that among those considered, poverty and nuclear war represent the greatest risks, followed by smoking and, in decreasing order of priority, industrial risks and poor diet.

Air Pollutants, Occupational↗
PubMedDate not supplied

Management of cyclosporine toxicity by reduced dosage and azathioprine.

While cyclosporine immunosuppression has improved the results of heart transplantation, nephrotoxicity and hypertension occurred in a large percentage of surviving patients. The potential irreversibility of these toxicities was noted in patients chronically exposed to cyclosporine. The immunosuppressive protocol was modified in those patients with a serum creatinine greater than 2.5 mg/100 mL. Azathioprine was added to the immunosuppressive regimen, and the dose of cyclosporine was steadily decreased until the creatinine was lowered. The combination of low-dose cyclosporine and azathioprine provided effective immunosuppression and was associated with a significant decrease in serum creatinine level, in systolic and diastolic blood pressures. Although it is premature to assess the long-term results of this immunosuppressive protocol, the early results are encouraging.

Azathioprine↗