Medical treatment of peripheral arterial disease in the elderly / 老年心脏病学杂志（英文版）

Smoking should be stopped and hypertension, diabetes mellitus, dyslipidemia, and hypothyroidism be treated in elderly patients with peripheral arterial disease (PAD). Statins reduce the incidence of intermittent claudication and improve exercise duration until the onset of intermittent claudication in persons with PAD and hypercholesterolemia. Antiplatelet drugs such as aspirin or clopidogrel, especially clopidogrel, angiotensin-converting enzyme inhibitors, and statins should be given to all persons with PAD. Beta blockers should be given if coronary artery disease is present. Exercise rehabilitation programs and cilostazol lengthen exercise time until intermittent claudication develops. Chelation therapy should be avoided.

Electromagnetic field strength levels surrounding electronic article surveillance (EAS) systems.

Electronic article surveillance (EAS) is used in many applications throughout the world to prevent theft. EAS systems produce electromagnetic (EM) energy around exits to create an EM interrogation zone through which protected items must pass before leaving the establishment. Specially designed EAS tags are attached to these items and must either be deactivated or removed prior to passing through the EAS EM interrogation zone to prevent the alarm from sounding. Recent reports in the scientific literature have noted the possibility that EM energy transmitted by EAS systems may interfere with the proper operation of sensitive electronic medical devices. The Food and Drug Administration has the regulatory responsibility to ensure the safety and effectiveness of medical devices. Because of the possibility of electromagnetic interference (EMI) between EAS systems and electronic medical devices, in situ measurements of the electric and magnetic fields were made around various types of EAS systems. Field strength levels were measured around four types of EAS systems: audio frequency magnetic, pulsed magnetic resonant, radio frequency, and microwave. Field strengths from these EAS systems varied with magnetic fields as high as 1073.6 Am(-1) (in close proximity to the audio frequency magnetic EAS system towers), and electric fields up to 23.8 Vm(-1) (in close proximity to the microwave EAS system towers). Medical devices are only required to withstand 3 Vm(-1) by the International Electrotechnical Commission's current medical device standards. The modulation scheme of the signal transmitted by some types of EAS systems (especially the pulsed magnetic resonant) has been shown to be more likely to cause EMI with electronic medical devices. This study complements other work in the field by attaching specific characteristics to EAS transmitted EM energy. The quantitative data could be used to relate medical device EMI with specific field strength levels and signal waveforms. This is one of several efforts being made by the FDA, the electronic medical device industry and the EAS industry to mitigate the potential for EMI between EAS and medical devices.

Sustained hemodynamic and antianginal effects of high dose oral isosorbide dinitrate.

Small doses of oral nitrates are ineffective antianginal agents. However, large doses of oral nitrates individually titrated to produce long-acting hemodynamic effects may be effective antianginal agents in many patients. The dose of nitrate prescribed should be titrated by blood pressure and heart rate measurements, the presence of adverse side effects, and by exercise tolerance studies before and during treatment. We would strongly recommend gradual reduction rather than an abrupt discontinuation of chronic, high-dose nitrate therapy in patients with angina pectoris to avoid possible nitrate dependence withdrawal effects. We would also recommend that continuous nitrate antianginal prophylaxis not be used in patients with angina pectoris whose symptons are readily controlled with less intensive nitrate therapy used as needed. Partial hemodynamic tolerance develops after chronic use of high-dose oral isosorbide dinitrate but the antianginal efficacy of both sublingual nitroglycerin and of high doses of oral isosorbide dinitrate is unimpaired. Patients with congestive heart failure have also had clinical and hemodynamic improvement following chronic nitrate therapy.

National Cancer Institute study: evaluation of computed tomography in the diagnosis of intracranial neoplasms. IV. Meningiomas.

Intracranial meningiomas were detected in 164 of the 2,928 patients in the National Cancer Institute study of computed tomography (CT) in the diagnosis of intracranial tumors. The comparative effectiveness of contrast-enhanced and noncontrast CT scanning and other radiological modalities--plain skull radiography, angiography, radionuclide studies, and pneumoencephalography--was assessed. CT was demonstrated to be the most accurate method for detecting intracranial meningiomas (accuracy of 84.8% for noncontrast and 96.2% for contrast-enhanced CT). It was significantly more accurate than radionuclide studies and plain radiography, and was slightly more accurate than angiography. Pneumoencephalography was performed in only five cases, and identified a mass in four. Angiography was useful for increasing the percentage of specific diagnoses.

Iron content of pigmented villonodular synovitis detected by computed tomography.

Pigmented villonodular synovitis is a rare lesion in which iron is accumulated. A CT scan performed on one such lesion demonstrated significantly increased attenuation values. We have calculated the amount of iron which would have to be added to muscle tissue in order to produce this increase in density. We have also measured the iron content directly. The close agreement of these two figures suggests that the observed density increase is due to the iron content of the lesion.

Computed tomography scanning for the measurement of bone mineral in the human spine.

An investigation into the feasibility of using X-ray computed tomography (CT) to measure disease induced changes in bone mineral content of the human spine is described. A theoretical study of this type of measurement has been made using a mathematical model of osteomalacia. The measured EMI number changes linearly with the mineral content, and the sensitivity is shown to be 1.2 EMI units (EU: 500 scale)/1% change in mineral content in vertebral bone. The physical sensitivity to an equal mineral change in cortical bone is found to be 8.6 times greater. The mineral selectivity of the CT method is such that only about half the change in the EMI number arising from progressive osteomalacia reflects change in actual mineral content, while half is due merely to changes in bone density that accompany demineralization. In addition, the perturbing effects of beam hardening on measurement accuracy are evaluated and shown to be significant. Finally, an experimental measurement indicates that in practice the reproducibility of such measurements would be about 1 EU, and it is shown that the measured parameter correlates well with the calculated total linear attenuation coefficients.

[The use of computerized tomography in the detection of intra-orbital foreign bodies].

Use of the CT scanner as an instrument for foreign body detection and localization was explored under experimental conditions. The results show that a sufficiently dense radiopaque foreign body as small as 0.7mm3 can be detected and localized by presently available scanners.

Attenuation measurements of whole blood and blood fractions in computed tomography.

Computed tomography (CT) provides an extraordinarily effective means of diagnosing intracranial hemorrhages. Normal blood has a relatively high x-ray attenuation in the circulation and following extravasation, permitting the discrimination by CT of many pathologically enlarged vascular spaces containing circulating blood and/or blood clot (such as arteriovenous malformations and large aneurysms) in addition to recent hemorrhages, from continguous anatomical structures. To promote further understanding of the factors contributing to the attenuation of blood in normal and abnormal states. the attenuations of various preparations of whole blood and blood fractions were investigated in further detail.