Primary idiopathic optic neuritis in U.S. Air Force Aviators.

The records of 31 male aviators seen at the Ophthalmology Branch of the USAF Aeromedical Consultation Service (formerly the USAF School of Aerospace Medicine) for a diagnosis of primary idiopathic optic neuritis (PION) were reviewed. Each subject received comprehensive ophthalmologic and neurologic examinations. The long-term follow-up data were collected through repeat examinations and by survey. Despite 39% of aviators being grounded due to complications of their PION or multiple sclerosis (MS), many aviators diagnosed with PION may be safely returned to flying duties. However, any aviator diagnosed with PION has a risk of recurrence or a potential to develop systemic MS and must be carefully reevaluated and followed to ensure they remain a viable asset and do not compromise flight safety or mission completion.

Rapid removal of platelets from plasma utilizing the Hepcheck heparin removal filter.

We investigated whether Hepcheck heparin removal filters could remove residual platelets from platelet-poor plasma (PPP) without compromising samples for lupus anticoagulant (LA) testing. Furthermore we assessed what effect, if any, plasma filtration has on various clotting tests that form the foundation for LA testing. Citrated blood was obtained from 35 normal donors. Two sets of citrated tubes were processed in order to obtain PPP. Citrated blood was also obtained from a single donor to check the actual amounts of platelets removed by the Hepcheck filtration device. One set of PPP samples was filtered using the Hepchek filter device and the other was not processed, i.e. unfiltered. Prothrombin time (PT), activated partial thromboplastin time (APTT), and kaolin clotting time (KCT) were performed on both unfiltered and filtered samples that were tested immediately and after freezing at -70 degrees C for 24 h. Platelet counts on the single donor's citrated plasma were dramatically reduced after filtration. PT and APTT values showed small but statistically significant differences between unfiltered and filtered plasmas whether these were fresh or frozen samples. However, these differences were not clinically significant. KCT data showed statistical and clinical differences between unfiltered and filtered plasmas whether fresh or frozen plasmas were used. In contrast, KCT values were similar if unfiltered, fresh plasmas or filtered, frozen plasmas were used. Coagulation factor assays for factors VIII, IX and X were performed on both sets of PPP samples after freezing to determine if the filtration device affected these levels and would as a result, compromise APTT based lupus testing. Factor IX levels demonstrated a loss of activity following use of the device but no change was observed in factor VIII or factor X. Von Willebrand factor antigen and function as well as multimer structure were not affected by the filtration device in 10 normal donors. Filtering plasmas of two donors with a history of an LA dramatically prolonged clotting times for APTT, Dilute Viper Venom Time, mixing studies, and STACLOT LA tests in comparison with unfiltered plasmas. The data indicate that plasma filtration using the Hepchek device does not adversely affect coagulation testing. Furthermore samples requiring testing for the lupus anticoagulant can be filtered and subsequently frozen and compare favorably with freshly processed samples.

Peripheral blood lymphocyte apoptosis: a clue to the diagnosis of acute infectious mononucleosis.

OBJECTIVE: To describe the morphology and significance of apoptotic lymphocytes in peripheral blood smears of patients with acute infectious mononucleosis. To our knowledge this has not been previously reported. DESIGN: Peripheral blood smears from 27 patients with a positive heterophile antibody test were collected and reviewed for the presence of apoptotic lymphocytes. Flow cytometry was performed on three cases to document the previously described low expression of bcl-2 in lymphocytes in infectious mononucleosis. Four control patient populations comprising 80 cases were similarly screened for the presence of apoptotic lymphocytes. SETTING: The specimens were collected over a 3-month period in two laboratories at our tertiary care hospital; all specimens were processed according to a standard protocol. PATIENTS: Young adult military recruits and their spouses, military dependent adolescents, and retired military personnel. RESULTS: Twenty-four (88.9%) of 27 peripheral blood smears of patients with acute infectious mononucleosis contained readily identifiable apoptotic lymphocytes. Three (3.75%) of 80 control peripheral blood smears were identified with rare apoptotic lymphocytes, all occurring in patients with viral upper respiratory infections. CONCLUSIONS: The finding of apoptotic lymphocytes in a peripheral blood smear is useful in the differential diagnosis of infectious mononucleosis and neoplastic hematolymphoid processes.

Differentiation of segmented and band neutrophils during the early newborn period.

This prospective study evaluated the degree of inter-reader variability in the identification of segmented and band neutrophils from blood smears of full-term, healthy neonates. Wide inter-reader differences of band neutrophil identification and the immature to total neutrophil ratio were observed. Because of poor correlation between evaluators of the same blood smear, the clinical utility of the manual differential leukocyte count in the evaluation of neonates is limited.

Hostility in asymptomatic men with angiographically confirmed coronary artery disease.

The association of hostility and coronary artery disease was evaluated in a case-control study of aircrew members who had been referred for coronary angiography on the basis of noninvasive tests or risk factor status. The asymptomatic status of the sample and the structured nature of the referral process minimize the methodologic problems normally associated with studies of patients undergoing angiography. Cases (n = 24) had some angiographic evidence of coronary artery disease, whereas controls (n = 25) were found to have no evidence of occlusion. An interaction was observed between smoking history and a measurement of hostility based on observations of the respondent's behavior during a standard interview. Among nonsmokers, cases had higher hostility scores than did controls (p = 0.004). This association was not present among smokers. Self-reported hostility did not discriminate cases from controls. These findings support the notion that hostility plays a role in the pathogenesis of coronary atherosclerosis and point to the potential importance of interactions between hostility and other risk factors.

The West Point Study: 40 years of follow-up.

Completion of cardiovascular evaluations of 387 members marked the end of 40 years of follow-up in the West Point Study. Coronary artery disease (CAD) caused 4 cases of sudden death, 14 cases of myocardial infarction (MI), 13 cases of angina, and 17 cases of silent CAD. Using risk factors (serum cholesterol, estimated HDL-cholesterol, systolic blood pressure, and smoking status) measured before age 28, we derived a multivariate regression formula for predicting which members of the study, had they been pilots, would have been grounded for CAD before age 55. This derivation used data from only those subjects with CAD or with no evidence of CAD. We then used the formula to compute a risk-related score for each member of the study. In the tertile group with the highest risk-related scores, 17% manifested CAD by age 55 and the first event occurred at age 39. In the tertile group of lowest scores, 2% experienced CAD by age 55 and the first event occurred at age 51. We conclude that it is possible to select pilot candidates with the lowest risk for CAD.

Accuracy of exercise 201Tl myocardial scintigraphy in asymptomatic young men.

BACKGROUND: Little is known about the diagnostic usefulness of 201Tl scintigraphy for detecting asymptomatic coronary artery disease in apparently healthy men. We thus evaluated planar 201Tl exercise myocardial scintigraphy in 845 asymptomatic male military aircrew undergoing coronary arteriography because of abnormal noninvasive tests suggesting possible myocardial ischemia. METHODS AND RESULTS: Patients were stratified by prior disease risk into six subgroups using age (< 45 and > or = 45 years) and ratio of total to high density lipoprotein cholesterol (< 4.5, 4.5-6.0, and > 6.0). Significant coronary artery disease (> or = 50% diameter stenosis in any major coronary artery) was present in 143 (16.9% prevalence). Overall sensitivity and specificity of 201Tl scintigraphy adjusted for verification bias were estimated to be 45 +/- 4% and 78 +/- 1%, respectively. These values are lower than corresponding values accepted for clinical populations. Positive and negative predictive values varied across subgroups. A normal thallium scan indicated low risk of disease, but an abnormal test was likely to be a false-positive result. A logistic equation was retrospectively fit to the data for estimating the probability of disease given age, cholesterol ratio, and thallium results. Within each quintile of estimated risk, the average risk did not differ significantly from the observed disease prevalence. CONCLUSIONS: Exercise 201Tl scintigraphy is limited by the frequent occurrence of false-positive tests in detecting asymptomatic, anatomic coronary artery disease in young men in accordance with Bayesian probability theory.

Fluoroscopic coronary artery calcification and associated coronary disease in asymptomatic young men.

Little is known about the diagnostic significance of coronary artery calcification detected fluoroscopically in apparently healthy young men. This study compared the presence of fluoroscopically detected coronary artery calcification with angiographic coronary artery disease in asymptomatic male military aircrew undergoing noninvasive cardiac screening tests and coronary arteriography for occupational indications. Of 1,466 men screened with coronary fluoroscopy, 613 underwent coronary arteriography because of one or more abnormal noninvasive test results. The mean age (+/- SD) of all subjects screened was 40.2 +/- 5 years (range 26 to 65). Significant coronary artery disease (greater than or equal to 50% diameter stenosis) was found in 104 of the 613 subjects with arteriograms (16.9% disease prevalence). Overall sensitivity and specificity for coronary artery calcification detection of significant disease, based only on those subjects undergoing arteriography, were 66.3% and 77.6%, respectively. For measurable disease (mild plus significant), sensitivity was 60.6% and specificity 85.9%. Positive and negative predictive values were 37.7% and 91.9%, respectively, for significant disease. For measurable disease, positive and negative predictive values were 68.9% and 80.9%, respectively. In these asymptomatic young men, a fluoroscopic examination negative for coronary artery calcification indicated a low risk of significant coronary artery disease, whereas a positive test result (calcification present) substantially increased the likelihood of angiographically significant coronary artery disease.

Panel summary: from Zen riddle to the razor's edge.

A summary of the Panel on Deliberate G-induced Loss of Consciousness reviews the global issue of rendering human subjects unconscious in the centrifuge as a research procedure. Major issues summarized are informed consent, a common taxonomy for G-LOC events, and medical surveillance of subjects made deliberately unconscious.

High +Gz centrifuge training: the electrocardiographic response to +Gz-induced loss of consciousness.

Neural control of the heart involves complex interconnections within the central nervous system (CNS). Although various CNS abnormalities and processes (acute cerebrovascular accidents, cerebral ischemia, subarachnoid hemorrhages, and seizures) have been associated with alteration of cardiac electrophysiology, the effect of +Gz-induced loss of consciousness (G-LOC) on autonomic control of the heart is unknown. From a group of 59 healthy subjects undergoing centrifuge high +Gz training, 15 suffered G-LOC episodes. The +Gz training profiles included gradual (0.1 G/s) and rapid (approximately 6 G/s) exposures to levels as high as +9 Gz. Electrocardiographic rate and rhythm disturbances were evaluated during each of the +Gz training profiles. Rate and rhythm disturbances associated with the +Gz stress exposures were observed in 73% of the subjects. When considering only the period when the subjects were exposed to +Gz (During-G), 67% of the individuals had atrial or ventricular ectopy. When considering the period of unconsciousness (During-LOC), which lasted an average of 12.6 s, 33% of the individuals had atrial or ventricular ectopy. Electrocardiographic changes were related to +Gz stress and unrelated to the period of occurrence of G-LOC. Significant ectopy (ventricular tachycardia and supraventricular tachycardia) was observed only during +Gz stress and not related to the G-LOC period. The results of the study do not indicate that G-LOC alters the electrocardiographic response to +Gz stress.

Medication-induced performance decrements: cardiovascular medications.

Clinicians may not give complete consideration to the occupational and recreational impact that prescribed medications can have on patients. Because cardiovascular disease is a major health problem that affects a large segment of the adult population in the United States, a significant portion of the adult work force may be expected to be under treatment with cardiovascular medications. Many may experience decrements in job performance as a result of such therapy. This article discusses the incidence and impact of occupationally relevant side effects of several categories of cardiovascular drugs, including beta blockers, calcium channel blockers, antiarrhythmics, vasodilators, nitrates, lipid-lowering agents, and diuretics.

Ventricular ectopy in totally symptom-free subjects with defined coronary artery anatomy.

Ambulatory ECG recordings were obtained from 313 consecutive, totally symptom-free male subjects on whom cardiac catheterization was subsequently performed for occupational reasons. These recordings were examined for ventricular ectopy and the results were studied in relation to the findings on selective coronary angiography. Ventricular ectopy was a common finding, with 58% of those subjects with normal coronary artery anatomy having at least one ventricular premature beat during the period of monitoring (mean 16 1/2 hours), 22% having greater than one such complex per hour, and 10% having greater than 10 per hour. Complex ventricular ectopy was present in 21% of the normal subjects. No association between the extent or complexity of ventricular ectopy and the presence or grade of anatomic coronary artery disease was demonstrated, nor was ventricular ectopy overrepresented in those with both significant coronary artery disease on angiography and evidence of ischemia on provocative testing.

The West Point Study: occurrence of coronary artery disease after 34 years.

This report reviews the current status of the West Point Study and addresses the prediction of risk of coronary artery disease (CAD) based on cholesterol levels measured at various times during the study. Subjects were grouped into quintiles by their risk index score calculated from the Framingham risk equation. The number of cases of CAD among the subjects in each of the quintiles was tabulated. The cases of CAD in these quintiles increased from the lowest to the highest quintiles and produced a significant correlation between the risk score and the percent of subjects in the quintiles having CAD, even when the data used for calculating the risk scores had been collected up to 26 years earlier. The numbers of CAD cases are small; they are only approximately 50% of the expected numbers computed for U.S. males of comparable ages, despite the increases in serum cholesterol and low density lipoprotein levels recorded during the first 6 years of the study. The authors speculate about possible explanations of these findings.

Acceleration tolerance of asymptomatic aircrew with mitral valve prolapse and significant +Gz-induced ventricular dysrhythmias.

The +Gz tolerance of asymptomatic aircrew with mitral valve prolapse (MVP) who had advanced Lown grade ventricular ectopy (multiformed or paired premature ventricular contractions and ventricular tachycardia) during +Gz-stress testing was investigated. The +Gz tolerance to an aeromedical centrifuge stress testing protocol revealed that these individuals had slightly lower +Gz tolerance for each of the different types of +Gz profiles, with the gradual onset of +Gz while using an anti-G straining maneuver (GOR-S) tolerance being significantly lower (p less than 0.05). As a subgroup of a larger group of individuals with MVP, these MVP individuals with advanced ventricular ectopy had an increased incidence of +Gz-induced loss of consciousness and motion sickness. The advanced ventricular ectopy occurred before, during, and after +Gz stress; however, there was a tendency for the ectopy to occur in the post +Gz stress period. The post +Gz stress period is a period of high parasympathetic (vagal) tone, and these findings may indicate that these individuals are in some way sensitive to high vagal tone. Acceleration stress testing is a valuable tool in the aeromedical evaluation of asymptomatic individuals desiring to fly fighter aircraft. Advanced ventricular ectopy not seen in other clinical testing (treadmill and ambulatory monitoring) occurred in these individuals. The current results suggest that these individuals with MVP and advanced ventricular ectopy are not currently prime candidates for flying fighter aircraft, not only because of the ventricular ectopy, but because of decreased +Gz tolerance and susceptibility to +Gz-induced loss of consciousness.