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Biomedical subjects

D B Mark

Publications and source records attributed to D B Mark.

175 records · Page 10Linked to original sources
PubMed1985

Randomized trials of coronary artery bypass surgery: impact on clinical practice at Duke University Medical Center.

Trends in practice patterns at Duke University Medical Center were assessed in patient groups comparable to those enrolled in the three major randomized trials of coronary artery bypass grafting (CABG). In addition, changes in practice patterns that appeared unrelated to the randomized trials were examined. Most patients with 75% or greater left main stenosis have been treated surgically after publication of the Veterans Administration Cooperative Study, but little change was noted in the proportion of patients with 50% left main stenosis who have been treated surgically. A trend towards selection of surgical therapy for patients with three-vessel disease and normal left ventricular function was evident before the publication of the European Coronary Surgery Study, although one-third of patients in this category continue to be treated nonsurgically after publication of the results of the trial. For the past decade, most patients who would have been eligible for the Coronary Artery Surgery Study have been treated nonsurgically. We have also documented trends in practice patterns that are independent of the results of randomized trials. The advent of percutaneous transluminal angioplasty has provided another therapeutic alternative that has been used increasingly. In addition, growing numbers of patients with advanced age, unstable angina, or markedly depressed left ventricular ejection fraction are being evaluated with cardiac catheterization despite the lack of supporting randomized trials. Randomized trials have placed our understanding of the effects of CABG on a sound foundation, but it is evident that clinicians continue to consider many other factors when therapeutic decisions are made.

Academic Medical Centers↗
PubMed1984

Factors affecting sensitivity and specificity of exercise electrocardiography. Multivariable analysis.

Unlike the predictive value of a diagnostic test, which depends on the prevalence of disease in the population tested, its sensitivity and specificity have been assumed to be constants. This assumption was examined in patients who had both exercise electrocardiography and cardiac catheterization. The effects on sensitivity of factors from clinical history, catheterization, and exercise performance were defined by multivariable logistic regression analysis in 1,401 patients with coronary disease; effects on specificity were defined by a similar analysis in 868 patients without coronary disease. Five factors had significant, independent effects on exercise electrocardiographic sensitivity: maximal exercise heart rate, number of diseased coronary arteries, type of angina, and the patient's age and sex. Only maximal exercise heart rate had a significant, independent effect on exercise electrocardiographic specificity. Thus, the sensitivity and specificity of exercise electrocardiography vary with clinical history, extent of disease, and treadmill performance; the sensitivity and specificity of other diagnostic tests may also vary.

Adult↗
PubMed1984

Clinical characteristics and long-term survival of patients with variant angina.

We studied 109 consecutive patients with variant angina who underwent cardiac catheterization over an 11 year period. All patients were followed for at least 6 months or until death, and 46 patients (22 treated medically and 24 treated surgically) were followed for 5 years or more. Of the 62 patients initially treated medically, 14 had nonfatal myocardial infarctions (12 within 1 month of catheterization) and 12 died (six within 6 months). Survival probabilities at 1, 3, and 5 years were 0.88, 0.84, and 0.77, respectively. Of the 48 surgically treated patients (including four patients initially treated medically and one initially treated with coronary angioplasty), four had nonfatal infarctions (three in the perioperative period) and three died (all in the perioperative period). The survival probability in these patients at 1 year was 0.94 and remained unchanged at 3 and 5 years. Only one nonfatal infarction and no deaths have occurred in the group of surgically treated patients subsequent to hospital discharge. Three additional patients were treated with coronary angioplasty. The single most important prognostic factor in medically treated patients was the presence or absence of fixed obstructive coronary artery disease. Infarction-free survival probabilities at 1 and 3 years in the 23 patients without significant coronary artery disease were 1.0 and 0.89, compared with 0.51 and 0.46 in the 39 patients with significant coronary disease. Analysis by the Cox model showed that variant angina patients had a higher probability of death and nonfatal infarction than did those with nonvariant angina coronary disease if other important prognostic variables were held constant.(ABSTRACT TRUNCATED AT 250 WORDS)

Angina Pectoris, Variant↗
PubMed1983

Trauma-induced endophthalmitis caused by Acinetobacter anitratus.

A 56-year-old man sustained an intraocular injury by a piece of steel followed by endophthalmitis, which resolved after lensectomy, vitrectomy, and intravitreal injections of gentamicin. Acinetobacter anitratus was the organism responsible for the endophthalmitis. It is a Gram-negative polymorphic organism that can resemble several other pathogens and possesses unpredictable antibiotic susceptibility. A. anitratus is an important cause of nosocomial infection but has not previously been reported as a cause of endophthalmitis following trauma.

Acinetobacter Infections↗
PubMed1982

Reiter's keratitis.

A distinctive keratitis occurs commonly in Reiter's syndrome. In three patients with Reiter's keratitis, two demonstrated the typical features of prodromal conjunctivitis, subepithelial and anterior stromal infiltrates, ragged epithelial erosions, and spontaneous resolution. A third case of rare, severe keratitis in addition had an associated finding of disciform keratitis. To our knowledge, this last finding has not previously been reported. Chlamydia has been implicated as an etiologic agent in Reiter's syndrome. Giemsa's stain of corneal epithelial cells in one of our patients disclosed intracytoplasmic inclusions that resembled those seen in Chlamydia-caused conjunctivitis. The patient also exhibited a rising serum titer to Chlamydia antigen.

Adult↗
PubMed1975

Effect of exogenous catecholamines in the amygdala of a 'rage' cat.

Minute amounts of epinephrine or norepinephrine alter the behavior of 'rage' cats (prepared by ventromedial hypothalamotomy) when these substances are focally instilled into both amygdalae via chronic brain cannulae capped with a silastic membrane. Hyperactive defense reactions are replaced by lethargy and placidity. Similar injections of epinephrine or norepinephrine into the amygdalae of normally placid cats who had not been subjected to ventromedial hypothalamotomy did not appreciably alter their behavior.

Amygdala↗
PubMedDate not supplied

Clinical and economic lessons from studies of coronary thrombolysis.

The era of coronary reperfusion in acute coronary care was made possible by the recognition that acute myocardial infarction is usually due to a ruptured atherosclerotic plaque with associated thrombosis. If the infarct artery becomes occluded, a typical electrocardiographic picture is produced and a wave-front of myocardial necrosis ensues. Reperfusion during the early postinfarction hours can halt this process and preserve myocardial function. Pooled analysis of data in almost 60,000 patients has shown that thrombolysis saves lives relative to no reperfusion therapy. Streptokinase has been the standard thrombolytic agent, but recent data from the GUSTO trial show that tissue plasminogen activator (t-PA) given in an accelerated dosing regimen saves one extra patient per hundred treated. The mechanism of benefit of t-PA is improved early and complete restoration of blood flow down the infarct artery. Economic analysis of the GUSTO data shows that t-PA is an "economically attractive" therapeutic technology with a cost-effectiveness ratio of approximately $33,000 per life-year added relative to streptokinase therapy. Because of the growth of managed care and other cost-containment forces, expensive new medical technologies will increasingly need to demonstrate that they produce extra medical benefits in appropriate measure for their extra costs.

Adult↗
PubMedDate not supplied

Social support and hostility as predictors of depressive symptoms in cardiac patients one month after hospitalization: a prospective study.

OBJECTIVE: Hospitalization for cardiac disease is associated with an increased risk for depression, which itself confers a poorer prognosis. Few prospective studies have examined the determinants of depression after hospitalization in cardiac patients, and even fewer have examined depression within the weeks after hospital discharge. The present study assessed the prospective relations among perceptions of social support and trait hostility in predicting symptoms of depressive symptoms at 1 month after hospitalization for a diagnostic angiography in 506 coronary artery disease (CAD) patients. METHOD: A series of structural equation models 1) estimated the predictive relations of social support, hostility, and depressive symptoms while in the hospital to symptoms of depression 1 month after hospitalization, and 2) compared these relations across gender, predicted risk classification, and age. RESULTS: Social support assessed during hospitalization was independently negatively associated with depressive symptoms 1 month after hospitalization, after controlling for baseline symptoms of depression, gender, disease severity, and age. Hostility was an indirect predictor of postdischarge depressive symptomology by way of its negative relation with social support. This pattern of relations did not differ across gender, predicted risk classification, and age. CONCLUSIONS: Our findings suggest that a patient's perceived social support during hospitalization is a determinant of depressive symptoms 1 month later. The relation of social support and hostility to subsequent depressive symptoms was similar across a variety of populations.

Adult↗
PubMedDate not supplied

Depressive symptoms and survival of patients with coronary artery disease.

OBJECTIVE: Multiple studies have shown that high levels of depressive symptoms increase the mortality risk of patients with established coronary disease. This investigation divided depressive symptoms into groups to assess their relative effectiveness in predicting survival. METHODS: Questionnaires about the presence of depressive symptoms were administered to 1250 patients with significant coronary disease while they were hospitalized for diagnostic coronary angiography. Follow-up for mortality due to cardiac disease was conducted annually for up to 19.4 years. Factor analysis was used to divide items on the Zung Self-Rating Depression Scale into four groups: Well-Being, Negative Affect, Somatic, and Appetite. In addition, responses to a single item regarding feelings of hopelessness were available for 920 patients. RESULTS: Well-Being and Somatic symptoms significantly predicted survival (p < or = .01). Negative Affect items were also related to survival (p = .0001) and interacted with age. A 2-SD difference in the Negative Affect term was associated with a relative risk of 1.29 for patients >50 years old and 1.70 for younger ones. Only Negative Affect remained significant in a model with the other symptom groups. Hopelessness also predicted survival with a relative risk of 1.5. Both the Hopelessness and Negative Affect items remained as independent predictors in the same model. All models controlled for severity of disease and treatment. With one exception (income and Hopelessness), results were essentially unchanged by additional controls for age, gender, and income. CONCLUSIONS: Depressive symptoms differentially predicted survival, with depressive affect and hopelessness being particularly important. These effects were independent of disease severity and somatic symptoms and may be especially important in younger patients.

Coronary Disease↗
PubMedDate not supplied

Characteristics of socially isolated patients with coronary artery disease who are at elevated risk for mortality.

OBJECTIVES: Social isolation has been linked to poor survival in patients with coronary artery disease (CAD). Few studies have closely examined the psychosocial characteristics of CAD patients who lack social contact. METHODS: Social isolation was examined as a predictor of mortality in 430 patients with significant CAD. More isolated patients were compared with their less isolated counterparts on factors that might help explain the association between isolation and survival. RESULTS: The mortality rate was higher among isolated individuals. Those with three or fewer people in their social support network had a relative risk of 2.43 (p = .001) for cardiac mortality and 2.11 (p = .001) for all-cause mortality, controlling for age and disease severity. Adjustments for income, hostility, and smoking status did not alter the risk due to social isolation. With the exception of lower income, higher hostility ratings, and higher smoking rates, isolated patients did not differ from nonisolated patients on demographic indicators, disease severity, physical functioning, or psychological distress. Isolated patients reported less social support and were less pleased with the way they got along with network members, but they did not report less satisfaction with the amount of social contact received. CONCLUSIONS: Patients with small social networks had an elevated risk of mortality, but this greater risk was not attributable to confounding with disease severity, demographics, or psychological distress. These findings have implications for mechanisms linking social isolation to mortality and for the application of psychosocial interventions.

Aged↗
PubMedDate not supplied

Intracorneal lesions produced with focused ultrasound.

Focused ultrasound concentrates a large amount of ultrasonic energy into a small focal zone. We have used new techniques to develop a transducer that creates intracorneal, thermally induced lesions in rabbit eyes in vitro. Histologic study shows that these lesions are confined to the stroma and that the procedure causes no structural damage to the corneal epithelium or endothelium or other ocular structures. The potential uses of this device in corneal research and therapy are discussed.

Animals↗
PubMedDate not supplied

Prognostic importance of social and economic resources among medically treated patients with angiographically documented coronary artery disease.

OBJECTIVE: To evaluate the hypothesis that diminished social and economic resources impact adversely on cardiovascular mortality in patients with coronary artery disease. DESIGN: Inception cohort study of patients undergoing cardiac catheterization from 1974 through 1980 and followed up through 1989. SETTING: Tertiary care university medical center. PATIENTS: Consecutive sample of 1965 medically treated patients with stenosis 75% or greater of at least one major coronary artery. Five hundred patients were not enrolled due to logistic problems; 33 refused; 64 had missing data on key medical variables. The final study population included 1368 patients, 82% male, with a median age of 52 years. MAIN OUTCOME MEASURE: Survival time until cardiovascular death. RESULTS: Independent of all known baseline invasive and noninvasive medical prognostic factors, patients with annual household incomes of $40,000 or more had an unadjusted 5-year survival of 0.91, compared with 0.76 in patients with incomes of $10,000 or less (Cox model adjusted hazard ratio, 1.9; 95% confidence interval, 1.57 to 2.32; P = .002). Similarly, unmarried patients without a confidant had an unadjusted 5-year survival rate of 0.50, compared with 0.82 in patients who were married, had a confidant, or both (adjusted hazard ratio, 3.34; 95% confidence interval, 1.84 to 6.20; P less than .0001). CONCLUSIONS: Low levels of social and economic resources identify an important high-risk group among medically treated patients with coronary artery disease, independent of important medical prognostic factors. Additional study will be required to see if interventions to increase these resources improve prognosis.

Cardiac Catheterization↗