Refractory ceramic fibers (RCF) are manmade vitreous fibers (MMVF) manufactured for high-temperature applications. Between 1987 and 1992, a retrospective cohort and nested case-control study evaluated chest radiographs from 652 workers involved in the manufacture of these fibers for plausibility of a causal relationship between exposure to RCF and chest-radiographic changes. The exposure-response relationship was modeled with three variables: years since first fiber production job, years in fiber production, and cumulative fiber exposure to date of study X-ray. The case-control study used a comprehensive characterization of possible asbestos exposure to investigate asbestos as the potential causative agent of chest-radiographic changes. Chest radiographs of 20 workers (3.1%) demonstrated 19 pleural plaques and one diffuse pleural thickening. Nine of 72 workers (12.5%) with more than 20 yr since their first fiber-production job had plaques (odds ratio [OR] = 9.5; 95% confidence interval [CI] = 1.9 to 48.2). Five of 19 workers with more than 20 yr in fiber-production work (26.3%) had plaques (OR = 22.3; 95% CI = 3.6 to 137.0). Similarly, adjusted ORs demonstrated a progressive relationship between cumulative fiber-months per milliliter (fiber-mo/ml) exposure and plaques. The case-control study confirmed that asbestos exposure did not account for the observed association between fiber exposure and plaques. A validity review of historical films demonstrated biologic plausibility for the association, since sufficient latency existed from the time of first RCF exposure to the development of plaques. There was no significant increase in parenchymal changes consistent with interstitial fibrosis.

SUMMARY A case is reported in which a congenital aneurysm of the right coronary sinus of Valsalva ruptured and dissected into the interventricular septum. M-mode and cross-sectional echocardiographic examination allowed accurate preoperative assessment of the pathologic anatomy, which was confirmed by angiography, surgery and autopsy. Dissection of the interventricular septum by a congenital sinus of Valsalva aneurysm is a rare lesion, has a poor prognosis, and can be diagnosed noninvasively with echocardiography.CONGENITAL ANEURYSM of the sinus of Valsalva is frequently encountered in clinical practice. Recent studies have emphasized the wide variety of clinical manifestations of this lesion, depending on its location and course.'-' In this report we present a case in which a ruptured right coronary sinus of Valsalva aneurysm took an unusual course, dissecting into the muscular interventricular septum. We believe this to be the first report of the preoperative diagnosis of this condition.Case Report A 16-year-old black male presented to the University of Cincinnati Hospital emergency room for evaluation of left-sided chest pain related to slight trauma that occurred 2 days before. Physical examination revealed systolic and diastolic murmurs, and an ECG revealed complete left bundle branch block. A chest x-ray was interpreted as normal. The patient was referred for further cardiac evaluation.The patient was the product of a normal pregnancy, labor and delivery with no history of perinatal cyanosis or respiratory difficulties. His subsequent growth and development were unremarkable. There was no history consistent with rheumatic fever or heart disease. Specifically The findings of the initial diagnostic evaluation in May 1979 were consistent with severe aortic regurgitation. Cardiac catheterization was refused. During the ensuing 6 months, the patient developed vague chest pain and progressive exertional dyspnea. Two weeks before admission, the patient developed increasing orthopnea and a nocturnal nonproductive cough. One week later, dyspnea increased, accompanied by several episodes of syncope. He was admitted to the University of Cincinnati Hospital, Cincinnati General Division in November 1979 for evaluation of congestive heart failure.Physical examination revealed a tall, slender adolescent black male in mild respiratory distress. There were no stigmata of Marfan's syndrome. The blood pressure was 110/50 mm Hg in both arms. The heart rate was 110 beats/min and cervical venous pressure was normal. The carotid upstrokes were brisk, with rapid emptying. Auscultation of the lungs revealed bibasilar end-inspiratory rales. On cardiac examination, the apical impulse was in the fifth intercostal space 1 cm lateral to the midclavicular line. Prominent apical and parasternal lifts were palpated. In addition, there was a diastolic thrill along the left sternal border. The first heart sound was decreased in intensity; the second heart sound was single.

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