Annals of medicine
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Review Comparative Study
Cellular adaptations of the heart muscle to exercise training.
Exercise training is unique in that it represents a stress that elicits positive adaptations in the heart. Hallmark adaptations of the heart to training include resting and submaximal exercise bradycardia, increases in end-diastolic dimension, improved ventricular function, and an increase in the resistance of the heart to ischaemic insult. ⋯ Over the last 20-25 years, considerable effort has been directed towards identifying the cellular basis for the global adaptations of the normal and pathologically involved heart to endurance exercise training. It is the intent of this brief review to identify some of the known and hypothetical cellular adaptations that underlie the positive effects of endurance exercise training on the heart.
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Renal transplantation is the optimal form of renal replacement therapy leading to substantial improvement in the quality of life. It has rapidly become the standard treatment for end-stage renal disease in children. However, despite impressive short-term results significant long-term problems remain unsolved. ⋯ However, the metabolic differences between an adult and a growing and developing paediatric transplant recipient are not always adequately appreciated before these new therapies are initiated. In the near future, we are likely to see new and more efficient drugs become available. It is important that we try to understand their properties in children and use them and our current arsenal on an individual basis aiming at optimal graft survival but also at avoiding unnecessary adverse effects.
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Liquid-assisted ventilation, as an alternative ventilation strategy for respiratory distress, is progressing from theory and basic science research to clinical application. Biochemically inert perfluorochemical liquids have low surface tension and high solubility for respiratory gases. From early immersion experiments, two primary techniques for liquid-assisted ventilation have emerged: total liquid ventilation and partial liquid ventilation. ⋯ Additionally, nonrespiratory applications have expanding potential including pulmonary drug delivery and radiographic imaging. Since its use in neonates in 1989, liquid-assisted ventilation in humans has progressed to a variety of clinical experiences with different aetiologies of respiratory distress. The future holds the opportunity to clarify and optimize the potential of multiple clinical applications for liquid-assisted ventilation.
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Sudden arrhythmic death is the most common mode of death in Western countries. An increased understanding of the pathophysiology and trigger mechanisms of life-threatening ventricular tachyarrhythmias in patients with structural heart disease can provide a logical basis for improved therapeutic strategies in the prevention of sudden death. Analysis of heart rate variability (HRV) from ambulatory electrocadiographic recordings can identify the patients at increased risk for arrhythmic death after an acute myocardial infarction. ⋯ Recently, quantitative analysis of Poincaré plots of successive R-R intervals has shown that reduced long-term R-R interval variability, associated with episodes of beat-to-beat sinus alternans, is a specific sign of a propensity for spontaneous onset of ventricular tachycardia. These studies suggest that abnormal heart rate behaviour reflects an electrical instability favoring the onset of life-threatening arrhythmia and provide evidence that altered neurohumoral or autonomic regulation is an important trigger mechanism for the spontaneous onset of life-threatening arrhythmia. Future research in larger patient populations will reveal whether analysis of dynamic behaviour of cardiac electrical signals will give new insights into the mechanisms of life-threatening arrhythmias and help in the development of new therapeutic options for the prevention of sudden arrhythmic death.
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The term fibromyalgia describes a complex syndrome characterized by pain amplification, musculoskeletal discomfort, and systemic symptoms. Although its existence has been controversial, nearly all rheumatologists now accept fibromyalgia as a distinct diagnostic entity. In fact, in the United States it is the third or fourth most common reason for rheumatology referral. Exciting new insights into the aetiology, pathogenesis, diagnosis and treatment of fibromyalgia will be reviewed.