Circulation
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Comparative Study
Reduced alveolar-capillary membrane diffusing capacity in chronic heart failure. Its pathophysiological relevance and relationship to exercise performance.
The pulmonary diffusing capacity for carbon monoxide (DLCO) is reduced in chronic heart failure (CHF) and is an independent predictor of peak exercise oxygen uptake. The pathophysiological basis for this remains unknown. The aim of this study was to partition DLCO into its membrane conductance (DM) and capillary blood volume components (Vc) and to assess if alveolar-capillary membrane function correlated with functional status, exercise capacity, and pulmonary vascular resistance. ⋯ Reduced alveolar-capillary membrane diffusing capacity is the major component of impaired pulmonary gas transfer in CHF, correlating with maximal exercise capacity and functional status. DM may be a useful marker for the alveolar-capillary barrier damage induced by raised pulmonary capillary pressure.
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Adenosine has been proposed as one mediator for the preconditioning effect in the myocardium of some animals, but recent investigations have shown that this may not be the mechanism in the rat heart, although the effect itself is clearly demonstrable. The cellular energy state has been shown to be better in preconditioned hearts, and the role of ATP consumption has been discussed. The role of inhibition of mitochondrial F1F0-ATPase as a mechanism for the preservation of ATP in preconditioned hearts remains controversial. ⋯ The results indicate that preconditioning causes inhibition of rat heart mitochondrial ATPase that persists during reperfusion so that the enzyme is inhibited from the very beginning of the sustained ischemia. This inhibition leads to sparing of high-energy phosphates and improves the time-averaged energy state during ischemia. Although a causal relationship is difficult to prove, this reversible inhibition may contribute to postischemic recovery of the heart.
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Randomized Controlled Trial Comparative Study Clinical Trial
Exercise training improves left ventricular diastolic filling in patients with dilated cardiomyopathy. Clinical and prognostic implications.
Patients with dilated cardiomyopathy (DCM) often have left ventricular (LV) diastolic dysfunction that can precede the development of systolic dysfunction. Recent reports showed that exercise training (ET) improves the exercise capacity of these patients. Although this improvement is primarily due to peripheral adaptations, the contribution of LV diastolic filling has not been well defined. The purpose of this study was to determine whether ET can induce changes in LV diastolic filling that can account for an increase in exercise capacity and whether these changes can influence prognosis. ⋯ These data demonstrate that ET induces significant improvement in exercise capacity only in patients with DCM and a pattern of abnormal LV relaxation. The improvement in peak VO2 is significantly correlated with an increase in peak early filling rate and peak filling rate as well as a decrease in atrial filling rate. Doppler echocardiography may be a valuable tool in the prognostic assessment of patients with DCM who will benefit from exercise training.
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Multicenter Study Comparative Study
Atrial septal aneurysm in adult patients. A multicenter study using transthoracic and transesophageal echocardiography.
An atrial septal aneurysm (ASA) is a well-recognized abnormality of uncertain clinical relevance. We reevaluated the clinical significance of ASA in a large series of patients. The aims of the study were to define morphological characteristics of ASA by transesophageal echocardiography (TEE), to define the incidence of ASA-associated abnormalities, and to investigate whether certain morphological characteristics of ASA are different in patients with and without previous events compatible with cardiogenic embolism. ⋯ As shown previously, TEE is superior to the transthoracic approach in the diagnosis of ASA. The most common abnormalities associated with ASA are interatrial shunts, in particular patent foramen ovale. In this retrospective study, patients with ASA (especially with shunts) showed a high frequency of previous clinical events compatible with cardiogenic embolism; in a significant subgroup of patients, ASA appears to be the only source of embolism, as judged by TEE. Our data are consistent with the view that ASA is a risk factor for cardiogenic embolism, but thrombi attached to ASA as detected by TEE are apparently rare.
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Randomized Controlled Trial Comparative Study Clinical Trial
Long-term effects of varying intensities and formats of physical activity on participation rates, fitness, and lipoproteins in men and women aged 50 to 65 years.
Although exercise parameters such as intensity and format have been shown to influence exercise participation rates and physiological outcomes in the short term, few data are available evaluating their longer-term effects. The study objective was to determine the 2-year effects of differing intensities and formats of endurance exercise on exercise participation rates, fitness, and plasma HDL cholesterol levels among healthy older adults. ⋯ While older adults can benefit from initiating a regular regimen of moderate-intensity exercise in terms of improved fitness levels and small improvements in HDL cholesterol levels, the time frame needed to achieve HDL cholesterol change (2 years) may be longer than that reported previously for younger populations. Frequency of participation may be particularly important for achieving such changes. Supervised home-based exercise regimens represent a safe, attractive alternative for achieving sustained participation.