The role of adrenal venous sampling (AVS) in primary bilateral macronodular adrenocortical hyperplasia (PBMAH): a study of 16 patients

OBJECTIVE

Primary bilateral macronodular adrenocortical hyperplasia (PBMAH) is a rare cause of ACTH-independent Cushing's syndrome. Current guidelines recommend bilateral adrenalectomy for PBMAH, but several studies showed clinical effectiveness of unilateral adrenalectomy despite bilateral disease in selected patients. Our aim was to evaluate the gain of information which can be obtained through adrenal venous sampling (AVS) based cortisol lateralization ratios for guidance of unilateral adrenalectomy.

DESIGN

We performed a retrospective analysis of 16 patients with PBMAH and clinical overt cortisol secretion in three centers METHODS: Selectivity of adrenal vein sampling during AVS was defined as a gradient of cortisol or a reference adrenal hormone ≥2.0 between adrenal and peripheral vein. Lateralization was assumed if the dominant to non-dominant ratio of cortisol to reference hormone was ≥4.0.

RESULTS

AVS was technically successful in all patients based on absolute cortisol levels and in 13 of 16 patients (81%) based on reference hormone levels. Lateralization was documented in 8 of 16 patients. In patients with lateralization, in 5 of 8 cases this occurred toward morphologically larger adrenals, while in 3 patients lateralization was present in bilaterally identical adrenals. The combined volume of adrenals correlated positively with urinary free cortisol, suggesting that adrenal size is the dominant determinant of cortisol secretion.

CONCLUSIONS

In this study the gain of information through AVS for unilateral adrenalectomy was limited in patients with PBMAH and marked adrenal asymmetry.

Time to Diagnosis in Cushing's Syndrome: A Meta-Analysis Based on 5367 Patients

CONTEXT

Signs and symptoms of Cushing's syndrome (CS) overlap with common diseases, such as the metabolic syndrome, obesity, osteoporosis, and depression. Therefore, it can take years to finally diagnose CS, although early diagnosis is important for prevention of complications.

OBJECTIVE

The aim of this study was to assess the time span between first symptoms and diagnosis of CS in different populations to identify factors associated with an early diagnosis.

DATA SOURCES

A systematic literature search via PubMed was performed to identify studies reporting on time to diagnosis in CS. In addition, unpublished data from patients of our tertiary care center and 4 other centers were included.

STUDY SELECTION

Clinical studies reporting on the time to diagnosis of CS were eligible. Corresponding authors were contacted to obtain additional information relevant to the research question.

DATA EXTRACTION

Data were extracted from the text of the retrieved articles and from additional information provided by authors contacted successfully. From initially 3326 screened studies 44 were included.

DATA SYNTHESIS

Mean time to diagnosis for patients with CS was 34 months (ectopic CS: 14 months; adrenal CS: 30 months; and pituitary CS: 38 months; P < .001). No difference was found for gender, age (<18 and ≥18 years), and year of diagnosis (before and after 2000). Patients with pituitary CS had a longer time to diagnosis in Germany than elsewhere.

CONCLUSIONS

Time to diagnosis differs for subtypes of CS but not for gender and age. Time to diagnosis remains to be long and requires to be improved.

How case representations of medical students change during case processing - Results of a qualitative study

Objective: Representations are mental summaries of a clinical case and help in understanding a clinical problem. However, it is still largely unknown which clinical information medical students include in their case representations. In this study, therefore, the structure and quality of students' case representations were examined to better understand the diagnostic process and its relationship to diagnostic accuracy. What information do medical students include in their representations and is there an association between this information and the diagnostic accuracy? Method: 43 medical students in the fourth and fifth clinical year worked on four clinical cases. During the diagnostic process, they were asked three times per case to write a case representation. 516 representations were qualitatively evaluated using a content-based coding scheme. An analysis was made of the nature and composition of the clinical information. In addition, the association between the general representation structure and the correct case solution was examined. Results: At the beginning, students include most of the clinical information in their representation (66%), but as the case progresses, they begin to select the information offered (2nd representation 42%, 3rd representation 38%). The length of the representation (number of words) does not correlate with the correct case solution (r=-0.08-0.31). The representations do not depend on the case difficulty but have a significant individual component: the representations written by a student are formally very similar in all four cases (r=0.60-0.86). Conclusion: Medical students can select the relevant clinical information and include it in their case representations. Lack of representation does not seem to be a reason for misdiagnosis; Students' deficits in diagnosis are more likely due to knowledge gaps.

Asessing coronary heart disease risk and managing lipids

Elevated low-density lipoprotein (LDL) and below normal high-density lipoprotein (HDL) cholesterol are risk factors for coronary heart disease (CHD). According to clinical guidelines, LDL cholesterol is the primary target for lipid-altering therapy. Many patients who develop CHD have LDL and HDL cholesterol levels that fall within the desirable or low-risk category; consequently, conventional measurements of plasma lipids may not accurately detect high-risk patients. This article discusses the clinical significance of lipoprotein subclasses and methods of measurement. Assessing lipoprotein subclasses provides a more comprehensive and efficacious therapeutic approach compared with the standard lipid profile.

The accumulative effects of physical activity in hypertensive post-menopausal women

BACKGROUND

Lifestyle modifications, such as physical activity, are recommended as first-line or adjunctive therapy for hypertension. However, controversy exists regarding the type, amount, and intensity of physical activity for optimal blood pressure lowering.

DESIGN AND METHODS

This study evaluated the blood pressure changes in 18 post-menopausal, sedentary, untreated hypertensive women randomized to an individualized 8-week programme of intermittent moderate-intensity physical activity versus no change in physical activity. The physical activity group was asked to select activities (such as walking) to engage in physical activity for 10 min, three times a day, 5 days per week at an intensity of 50-60% heart rate reserve.

RESULTS

Independent T-tests were used to compare the difference in resting blood pressure between groups. After 8 weeks, resting blood pressure was 8/5 mmHg lower in the physical activity group (systolic blood pressure, P= 0.006 and diastolic blood pressure, P = 0.059). The between group differences remained significant after adjustment for age, baseline blood pressure and previous use of antihypertensive drug therapy.

CONCLUSION

These data show that hypertensive, post-menopausal women who engage in intermittent, moderate-intensity physical activity experience a reduction in blood pressure.

Lipid disorders in type 2 diabetes

Diabetes mellitus (DM) is a major risk factor for cardiovascular disease (CVD) in men and women. Type 2 is the most prevalent form of DM and is associated with a two to threefold increased risk of CVD morbidity and mortality. Insulin resistance, the fundamental defect of type 2 DM, is associated with a cluster of cardiovascular risk factors, one of which is dyslipidemia. This article discusses CVD risk in DM, characteristics of the atherogenic dyslipidemia, screening for abnormal lipids, clinical trial evidence for treatment of hyperlipidemia, and treatment approaches.

The effects of crossed leg on blood pressure measurement

BACKGROUND

It is clear that numerous factors influence an individual's blood pressure measurement. However, guidelines for accurately measuring blood pressure inconsistently specify that the patient should keep feet flat on the floor.

OBJECTIVE

To determine if the crossing of a leg at the knee during blood pressure measurement has an effect on the patient's blood pressure reading.

METHODS

A convenience sample of 100 hypertensive male subjects was selected from various outpatient clinics in an inner-city acute-care veterans' hospital. The first 50 subjects positioned their feet flat on the floor while their blood pressure was measured. After 3 minutes, the blood pressure was measured again with the subject's leg crossed at the knee. The procedure was reversed for the second 50 subjects.

RESULTS

The results indicated that both systolic and diastolic blood pressure increased significantly (p < .0001) with the crossed leg position.

CONCLUSION

When blood pressure is measured, patients should be instructed to have feet flat on the floor to eliminate a potential source of error.

The influence of self-efficacy on exercise intensity, compliance rate and cardiac rehabilitation outcomes among coronary artery disease patients

Self-efficacy is increasingly used as a predictor of health behavior. The purpose of this study was to examine the impact of exercise self-efficacy on exercise behaviors and outcomes. A one-group pre-test/post-test design was used. The treatment, a 12-week exercise training program, was executed between the pre- and post-tests. Exercise self-efficacy was measured prior to training and at the 4th, 8th and 12th weeks of training. Estimated VO2max, fatigue, anxiety, depression, and quality of life (QOL) were assessed prior to exercise training and after 12 weeks of training. Compliance rate and exercise intensity were computed at the 4th, 8th and 12th weeks of training. Results of this study revealed no relationship between exercise self-efficacy and compliance rate, nor between exercise self-efficacy and exercise intensity. The change in exercise self-efficacy after exercise training, rather than the initial self-efficacy level, was significantly related to exercise outcomes. Exercise intensity was more important in predicting the improvement of VO2max than was compliance rate. In contrast, compliance rate was more important in predicting the improvement of QOL than was exercise intensity.

Benefits of aerobic exercise after stroke

The debilitating loss of function after a stroke has both primary and secondary effects on sensorimotor function. Primary effects include paresis, paralysis, spasticity, and sensory-perceptual dysfunction due to upper motor neuron damage. Secondary effects, contractures and disuse muscle atrophy, are also debilitating. This paper presents theoretical and empirical benefits of aerobic exercise after stroke, issues relevant to measuring peak capacity, exercise training protocols, and the clinical use of aerobic exercise in this patient population. A stroke, and resulting hemiparesis, produces physiological changes in muscle fibres and muscle metabolism during exercise. These changes, along with comorbid cardiovascular disease, must be considered when exercising stroke patients. While few studies have measured peak exercise capacity in hemiparetic populations, it has been consistently observed in these studies that stroke patients have a lower functional capacity than healthy populations. Hemiparetic patients have low peak exercise responses probably due to a reduced number of motor units available for recruitment during dynamic exercise, the reduced oxidative capacity of paretic muscle, and decreased overall endurance. Consequently, traditional methods to predict aerobic capacity are not appropriate for use with stroke patients. Endurance exercise training is increasingly recognised as an important component in rehabilitation. An average improvement in maximal oxygen consumption (VO2max) of 13.3% in stroke patients who participated in a 10-week aerobic exercise training programme has been reported compared with controls. This study underscored the potential benefits of aerobic exercise training in stroke patients. In this paper, advantages and disadvantages of exercise modalities are discussed in relation to stroke patients. Recommendations are presented to maximise physical performance and minimise potential cardiac risks during exercise.

Physiological outcomes of aerobic exercise training in hemiparetic stroke patients

BACKGROUND AND PURPOSE

In hemiparetic individuals, low endurance to exercise may compound the increased energy cost of movement and contribute to poor rehabilitation outcomes. The purpose of this investigation was to describe how hemiparetic stroke patients responded to intense exercise and aerobic training.

METHODS

Forty-two subjects were randomly assigned to an exercise training group or to a control group. Treatments were given three times per week for 10 weeks in similar laboratory settings. Baseline and posttest measurements were made of maximal oxygen consumption, heart rate, workload, exercise time, resting and submaximal blood pressures, and sensorimotor function.

RESULTS

Only experimental subjects showed significant improvement in maximal oxygen consumption, workload, and exercise time. Improvement in sensorimotor function was significantly related to the improvement in aerobic capacity. After treatment, experimental subjects showed significantly lower systolic blood pressure at submaximal workloads during the graded exercise test.

CONCLUSIONS

We conclude that hemiparetic stroke patients may improve their aerobic capacity and submaximal exercise systolic blood pressure response with training. Sensorimotor improvement is related to the improvement in aerobic capacity.

Bandura's self-efficacy theory: a guide for cardiac rehabilitation nursing practice

To help patients achieve the greatest benefit from cardiac rehabilitation programs, nurses must assist them to modify unhealthy behaviors. Many cardiac rehabilitation programs, however, lack a theoretical foundation; therefore, interventions are usually executed without accounting for the complexities of human behavior, and little consideration is given to the difficulties encountered in altering unhealthy behavior patterns. Bandura's self-efficacy theory is considered a suitable model for cardiac rehabilitation because it provides a systematic direction which allows one to interpret, modify, and predict patients' behaviors. This article describes the development of and conceptual framework for Bandura's theory, how it provides a basis for measurement of self-efficacy, and how it may be applied to the study of cardiac rehabilitation. Finally, some research issues, which are related to applications of self-efficacy theory in cardiac rehabilitation are discussed.

The role of catecholamines, age, and fitness on blood pressure reactivity to dynamic exercise in patients with essential hypertension

OBJECTIVE

To determine the relationship between exercise blood pressure (BP) and catecholamine levels in hypertensive subjects and, secondarily, to evaluate the influence of age and fitness level.

DESIGN

Descriptive correlational.

SETTING

Midwestern, university-affiliated medical center.

SUBJECTS

27 hypertensive subjects, mean age 45 years, who were free of antihypertensive medications.

OUTCOME MEASURES

BP and plasma catecholamines (norepinephrine and epinephrine).

INTERVENTION

Subjects were given an incremental maximal exercise test on a cycle ergometer beginning at 25 watts with workloads increasing by 25 watts every 2 minutes until exhaustion. Plasma catecholamines were measured at rest, at 100 watts, and at maximal exercise. BP, heart rate, and oxygen consumption (VO2) were measured at rest and at the end of each workload.

RESULTS

Systolic and diastolic BP were unrelated to catecholamines at rest and during exercise. When subjects were evaluated according to fitness level (VO2max), resting BP was not significantly different among groups (low fitness = VO2max < or = 25 ml/kg/min; moderate fitness = VO2max 26 to 39 ml/kg/min; high fitness = VO2max > or = 40 ml/kg/min). However, an inverse relationship was observed between fitness level and rate of rise of systolic and diastolic BP during submaximal work. Multiple regression showed that fitness predicted diastolic BP response (p = 0.02) at 100 watts. Age, however, predicted systolic BP response (p = 0.015).

CONCLUSIONS

Neither the level of resting nor the magnitude of BP response to exercise in hypertensive subjects was directly related to level of plasma catecholamines. The magnitude of change in BP during exercise was modulated by age and fitness level.

Physiologic versus pathologic hypertrophy: endurance exercise and chronic pressure overload

Endurance exercise requires that the heart maintain a highly elevated cardiac output for an extended period of time, working against a slightly elevated afterload. Endurance athletes manifest a large ventricular volume, characterized on echocardiogram by an increased end-diastolic internal diameter and wall thickness. This article describes the structural, functional, and biochemical alterations in the heart as a result of the physiologic stress of exercise, along with the signaling mechanisms for these changes. The article also compares exercise-induced hypertrophy and hypertrophy from chronic pressure overload.

The relationship of resting and exercise blood pressure in subjects with essential hypertension before and after drug treatment with propranolol

OBJECTIVE

To investigate the relationship between clinic resting blood pressure (BP) and exercise BP in subjects with established essential hypertension during placebo and propranolol-treated phases.

DESIGN

Prospective, placebo-controlled, cross-over trial.

SETTING

University-affiliated medical center.

PATIENTS

A convenience sample of 38 patients with essential hypertension, 34 men and four women, who ranged in age from 22 to 62 years (mean = 44 years, SD = 10.7). Subjects were diagnosed with mild to moderate diastolic or mixed systolic/diastolic essential hypertension at least 1 year before study entry. They had no clinical evidence of secondary hypertension, diabetes, heart, liver, pulmonary, or renal disease.

OUTCOME MEASURES

Resting and exercise BP.

INTERVENTION

Antihypertensive medication was tapered off and subjects were free of all prescription drug treatment for 2 weeks. They received placebo for an additional 2 weeks. Subjects then received treatment with propranolol at a dose necessary to control resting blood pressure for 4 to 6 weeks. At the end of both the untreated and treated phases, subjects were given a graded maximal exercise test on a bicycle ergometer.

RESULTS

Propranolol effectively reduced mean resting and maximal exercise BP. The nonsignificant correlation between clinic resting and maximal exercise systolic BP was low in both phases. The correlation between clinic resting and maximal exercise diastolic BP was only moderate, but statistically significant (untreated, r = 0.43; p < 0.01; treated, r = 0.53; p < 0.001). For systolic BP or diastolic BP, there were no significant relationships between percent drop in BP because of propranolol at rest or maximal exercise. Clinic resting BP was not a valid predictor of maximal exercise BP. Degree of control of clinic resting BP was not a valid predictor of control observed at maximal exercise.

CONCLUSIONS

Resting BP should not be used as a predictor of BP during maximal exercise in the untreated condition or with treatment with propranolol.

Exercise physiology and cardiovascular fitness

Endurance exercise training produces numerous metabolic and cardiovascular effects. Metabolic adaptations include an increase in oxidative capacity of skeletal muscle (greater number and size of mitochondria); an increase in skeletal muscle myoglobin concentration; a greater ability to oxidize fatty acids for energy; and an increase in stored glycogen. Cardiovascular effects of training include a decrease in resting heart rate and heart rate response to submaximal exercise; an increase in resting and exercise stroke volume; an increase in maximal cardiac output; an increase in VO2max; and an increase in arteriovenous oxygen difference. Aerobic exercise training contributes to cardiovascular fitness, because it beneficially alters the coronary artery disease risk profile. An inverse relationship exists between physical fitness and resting heart rate, body weight, percent body fat, serum cholesterol, triglycerides, glucose, and systolic blood pressure. In addition, exercise training increases the high-density lipoprotein fraction of total cholesterol. Endurance exercise is any activity that uses large muscle groups, can be performed continuously, and is rhythmic and aerobic in nature. To develop and maintain cardiovascular fitness, this exercise should be performed at a frequency of 3 to 5 days per week, an intensity of 60% to 90% HRmax or 50% to 85% HRmax reserve, and a duration of 20 to 60 minutes.

Preservation of ischemic myocardium through activity management

Myocardial ischemia results from an imbalance between oxygen supply and demand. This balance may be restored by medications, procedures to reperfuse the myocardium (eg, angioplasty or thrombolytic therapy), or a reduction of oxygen demand. Studies that have quantified the energy costs of physical activity (eg, toileting methods, bathing, range of motion exercises, and ambulation) by measuring oxygen consumption have confirmed that early mobilization causes no deleterious increase in myocardial oxygen demand in MI patients. The care of patients who have undergone reperfusion by thrombolytic therapy or angioplasty within hours of MI raises special considerations with regard to activity management and length of hospitalization. Although activity progression following MI has been shown to be relatively risk free, the authors recommend individualization of protocols and close monitoring of physiologic parameters to evaluate activity tolerance. Because MI is becoming increasingly more common in groups other than middle-aged men, additional research should be focused on specific subgroups (ie, elderly patients, women, patients who have sustained multiple MIs, and those who have had reperfusion therapies).

Calcium channel blockers for the treatment of coronary artery spasm: rationale, effects, and nursing responsibilities

Coronary artery spasm is recognized as a cause of ischemic heart disease, producing a syndrome of the variant form of angina that occurs at rest. Spasm also may play a role in other types of rest angina (unstable angina) and exertional angina. Calcium is essential for the basic tonus of vascular smooth muscle. The accentuated contraction that occurs in coronary artery spasm is the result of an increase in intracellular calcium ions. Current therapy is aimed at blocking the slow calcium currents that are responsible for electrical activation and contraction of smooth muscle cells. A marked coronary vasodilatation is produced with calcium channel blockers, thus demonstrating effective therapy for coronary artery spasm. A similar effect is achieved by nitrates, and these agents will continue to have a role in the therapy of spasm. Calcium channel blockers produce beneficial effects on myocardial oxygen supply and demand and, therefore, are also useful in the prevention of classic exertional angina caused by fixed obstruction. Verapamil and diltiazem possess electrophysiologic effects and have, in addition, proved useful in the treatment of supraventricular dysrhythmias.