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Biomedical subjects

S W Miller

Publications and source records attributed to S W Miller.

At least 55 records · Page 3Linked to original sources
PubMed1986

Cross-sectional imaging of silent pulmonary venous anomalies.

An overview of the forms of partial anomalous pulmonary venous connections (PAPVC) and a discussion of the role of computed tomography (CT) in diagnosing this anomaly are offered. Although angiography remains the most sensitive technique for detection of anomalous pulmonary veins and other cardiac anomalies, the increased use of CT over the past decade has probably resulted in the detection of PAPVC that otherwise might have been missed. In the case of asymptomatic PAPVC, CT may provide positive identification and obviate the need for further studies.

Humans↗
PubMed1986

Magnetic resonance imaging of thoracic aortic aneurysms: comparison with other imaging methods.

Fifteen patients with thoracic aortic aneurysms had magnetic resonance images (MRI) and at least one additional diagnostic image study: thoracic aortography, computed tomography (CT), or two-dimensional echocardiography. Twenty aneurysms were demonstrated by MRI, 19 by the other studies. One small saccular aneurysm was missed by CT. There was complete agreement between MRI and other studies regarding aneurysm morphology, and good correlation in diameter measurements of the aneurysms and at multiple additional aortic levels.

Adolescent↗
PubMed1985

Method for estimating right ventricular volume by planes applicable to cross-sectional echocardiography: correlation with angiographic formulas.

Right ventricular (RV) volumes determined by echocardiography were compared with those measured using established angiographic formulas. RV cast displacement volumes were first correlated with data derived from radiographic images of the casts corresponding to standard angiographic RV views. Four established angiographic formulas (Ferlinz, Boak, Fisher and Thilenius) correlated well with cast volume, with the corrected prism method of Fisher showing a best fit (r = 0.98, y = 1.1 + 0.9 x, standard error of the estimate = 3.6). Cast volumes calculated using our echocardiographic formula were then examined relative to the volumes derived from radiographic images of the RV casts. Volumes calculated using the corrected area-length Thilenius formula correlated best with those obtained using our derived 2-dimensional echocardiographic formula (r = 0.96, y = 4.6 + 1.0 x, standard error of the estimate = 6.8). These data confirm that volume calculated using the suggested optimal echocardiographic formula correlates well with volume obtained using derived angiographic data. Accordingly, confirmation in humans by the use of angiography is a rational step.

Adult↗
PubMed1985

Radiation exposure and protection in cardiac catheterization laboratories.

Cardiac catheterization with angiography can deliver the greatest dose of x-radiation of any diagnostic medical examination. The physicians and technologists in the angiography room receive low-level scattered radiation over a period of months to decades. Although the radiobiology is complex, the physicians who perform cardiac catheterization should be familiar with the potential genetic and somatic effects of radiation and with the methods to reduce or eliminate x-ray exposure. The aim of radiation protection criteria is to reduce the risk of cancer death to less than the fatality risk for other occupations regarded as safe. This report is a review of the literature relating to radiation exposure and protection in cardiac catheterization laboratories. Catheterization personnel have control over the time duration of exposure, placement of technologists, shielding, location of equipment and monitoring of dose received.

Adult↗
PubMed1985

Fractures of the distal forearm in Newcastle: an epidemiological survey.

The incidence of fractures of the distal radius and ulna in a defined adult population was studied over one year. Freezing temperatures were usually associated with a fourfold increase in fracture incidence, but there was no other seasonal trend. Incidence in men showed no relation to age. In women incidence rates increased sharply between the age groups 40-44 and 55-59 years and then continued to rise less steeply until ages 65-69 after which rates stabilized at a lower level. This pattern contrasts with the age- and sex-specific incidence of fractures of the proximal femur and of falls at post-retirement ages, and supports the hypothesis that one cause of fractures of the proximal femur in old age is failure of protective reflexes.

Adult↗
PubMed1985

Magnetic resonance imaging of the heart using image planes oriented to cardiac axes: experience with 100 cases.

Electrocardiographically gated magnetic resonance images were acquired in 100 patients with a variety of cardiac diagnoses in planes oriented to intrinsic axes of the heart and aorta. The technique used combines patient positioning and alteration of magnetic gradient angle. Images in these planes appear to have advantages over conventional orthogonal images, both for display of cardiovascular anatomy and for evaluation of cardiac size and function.

Adolescent↗
PubMed1985

A comparison of a multi-media instructional module with a traditional lecture format for geriatric pharmacy training.

The purpose of this study was to develop, produce, and test the effectiveness of a multi-media instructional module versus a traditional lecture format. The subject selected was geriatric care in relation to pharmacy practice. A pretest/posttest control group design was used, differing only in the method of presentation of the material. The control group received four fifty-minute traditional lectures, and the treatment group utilized the module for the acquisition of the information. An evaluation of the pretest scores showed that the groups were equal in knowledge (no significant difference at P = 0.05) before exposure to the information. A comparison of the posttest scores of the two groups showed that the module was as effective a learning strategy as the traditional lectures (no significant difference at P = 0.05). The comparison of the pretest and posttest scores within each group showed that significant improvement occurred following the utilization of both methods of instruction at P less than 0.05. The results of this project indicated that the module is an effective learning strategy when compared to a traditional lecture format. It was also evident that the multi-media module can be used as an instructional alternative in the education of pharmacy students.

Analysis of Variance↗
PubMed1985

Assessing the adequacy of myocardial perfusion in man: anatomic and functional techniques.

The dynamic nature of the coronary vasculature and its stenoses frequently requires more than a subjective anatomic visualization to evaluate potential myocardial ischemia. Although coronary arteriography can assess stenoses of no hemodynamic importance (less than 20 per cent diameter reduction) and lesions that severely impair blood flow (greater than 80 per cent diameter reduction). Most coronary stenoses fall between these two extremes. Quantitative arteriography and radioisotope perfusion studies can improve the accuracy of predicting myocardial ischemia.

Collateral Circulation↗
PubMed1985

Cardiac magnetic resonance imaging: the Massachusetts General Hospital experience.

The combination of gated cardiac imaging with the magnetic resonance parameters of flow void and tissue characterization forms the basis for a powerful noninvasive technique for imaging the cardiovascular system. Images constructed in planes orthogonal to the axis of the heart allow cardiac structures to be reproducibly detected in serial studies and measured. The data acquisition techniques used at Massachusetts General Hospital are presented, along with examples of their application in a variety of cardiac diseases. Future prospects are illustrated with flow-encoded images and with surface coil techniques.

Aorta↗
PubMed1984

Aortic root abscess resulting from endocarditis: spectrum of angiographic findings.

Abscesses in the aortic root are a serious complication of infective endocarditis and require accurate diagnosis for antibiotic and surgical management. Nineteen cases of endocarditis of a native valve or prosthetic valve and adjacent abscess cavities were identified with angiography. Of 6 patients with endocarditis of a native valve, 5 had bicuspid aortic valves and all had severe aortic regurgitation. Of 13 patients with endocarditis of a prosthetic aortic valve, all had paravalvular regurgitation. Abscesses in the aortic root were saccular, ranged from 1 to 3 cm in diameter, and, depending on sinus of origin, extended beneath the main and right pulmonary arteries or into the interventricular septum or mitral anulus. Fistulas were detected into the mitral anulus in 8 patients, and into the right ventricle in 3 patients. No complications from the catheterization were recorded during the 48-hour follow-up.

Abscess↗
PubMed1983

Visual modulation of neuronal activity within the rat vestibular nuclei.

Sixty-two of 95 units within the vestibular nuclei of 24 hooded, Long-Evans rats were found to respond to both linear accelerations on a parallel swing and to linear movements of the visual field. The addition of visual clues during periods of linear accelerations produced a phase shift in the majority of the units towards the maximal acceleration of the animal, and an increase in the peak activity during the periods of maximal acceleration. Conflicting visual-vestibular stimulation resulted in reduced directional sensitivity and lower rates of firing in visually sensitive units.

Animals↗
PubMed1981

Congenital extracardiac shunts with tetralogy of Fallot.

Congenital extracardiac shunts in tetralogy of Fallot may significantly alter the history and clinical findings and also have significant management implications. An unusual variant of severe tetralogy of Fallot in a 54-year-old man enabled long survival with minimal symptoms. The patient had pulmonary valvular and infundibular stenosis, a large ventricular septal defect, an overriding aorta, and large volume systemic-to-pulmonary artery shunting from his right internal mammary and accessory internal mammary arteries to his right pulmonary artery.

Coronary Circulation↗
PubMed1980

Scintigraphic assessment of false left ventricular aneurysms.

After myocardial infarction, patients may develop congestive heart failure, arrhythmias, or peripheral emboli due to true or false left ventricular aneurysms. False ventricular aneurysms differ from true aneurysms in that has been rupture of the left ventricular myocardium into the pericardium without rupture of the pericardial sac. The diagnosis of false aneurysm is particularly important because, in addition to the problems cited, there is a high incidence of rupture that may be prevented with surgical intervention. Four patients presenting with congestive heart failure and studied by gated cardiac blood pool scintigraphy were shown to have false left ventricular aneurysms and confirmed angiographically or surgically. Technetium-99m-gated cardiac blood pool scintiscans demonstrated discrete paraventricular chambers usually posterior in position with marrow necked connections to the left ventricle. Thallium-201 rest myocardial perfusion scintiscans performed in two of the four patients demonstrated a defect corresponding to the neck of the false aneurysm in one patient and a larger defect in the second patient with both a true and false aneurysm. It was concluded that combined gated cardiac blood pool scintigraphy and 201Tl myocardial scintigraphy provide a noninvasive method for diagnosing false left ventricular aneurysms.

Aged↗
PubMed1979

Assessment of drug intervention on the ischemic myocardium: serial imaging and measurement with computerized tomography.

Computerized tomography was evaluated as a technique for imaging and measuring the effect of an intervention on acutely ischemic myocardium. Because cell edema occurs with acute myocardial ischemia and decreases the X-ray attenuation coefficients (tissue density) of myocardium, computerized tomographic images were used to quantitate the effect of hyperosmotic mannitol on ischemia-induced edema. Canine hearts were arrested and scanned after (1) temporary occlusion of the proximal circumflex artery followed by reflow of blood, or (2) continued occlusion of the distal left anterior descending coronary artery. X-ray attenuation values (Hounsfield units) were linearly related to tissue wet/dry weight ratios (r = 0.87, P less than 0.001). After 2 hours of occlusion of the left anterior descending coronary artery the hearts that received mannitol manifested a significant reduction (P less than 0.05) in the volume of left ventricular wall involved with edema. Although the area of edema measured with computerized tomography tended to be smaller in the hearts treated with mannitol than in untreated hearts subjected to a 6 hour occlusion of the left anterior descending coronary artery, the size of the lesion was variable and did not differ significantly from that in untreated hearts. With either short periods of circumflex arterial occlusion followed by blood reflow or with 2 or 6 hours of prolonged occlusion of the left anterior descending coronary artery, the difference in mean attenuation coefficients between the ischemic and nonischemic areas of myocardium in mannitol-treated and untreated hearts was significantly less. These results indicate that computerized tomography in the arrested heart can detect and quantitate the lesion of early acute myocardial ischemia and can quantitate the effect of drug intervention.

Animals↗