British heart journal
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British heart journal · Oct 1995
Inspiratory muscle strength is a determinant of maximum oxygen consumption in chronic heart failure.
To investigate the significance of respiratory muscle weakness in chronic heart failure and its relation both to maximum oxygen consumption during cardiopulmonary exercise testing and to skeletal muscle (quadriceps) strength. ⋯ Respiratory muscle weakness is seen in chronic heart failure. The results suggest that inspiratory muscles are important in determining maximum oxygen consumption and exercise tolerance in these patients. The lack of correlation between respiratory and right quadriceps muscle strength further suggests that the magnitude and time course of respiratory and locomotor muscle weakness may differ in individual patients. Treatment aimed at improving the function of the involved muscle groups may alleviate symptoms.
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British heart journal · Oct 1995
Anatomical dead space, ventilatory pattern, and exercise capacity in chronic heart failure.
Patients with chronic heart failure have an excessive ventilatory response to exercise, characterised by an increase in the slope of the relation between ventilation and carbon dioxide production (VE/VCO2 slope). Patients have an altered respiratory pattern with an increased respiratory rate (f) at a given tidal volume (VT), which may result in increased anatomical dead space ventilation. ⋯ The relation between anatomical dead space ventilation and VE/VCO2 slope is expected: as f increases, so do VE/VCO2 slope and anatomical dead space ventilation. The VT/f slope was the same in patients with chronic heart failure and controls, so change in respiratory pattern cannot explain the increase in VE/VCO2 slope. The stimulus causing the increased f has yet to be identified.
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British heart journal · Oct 1995
Early diastolic left ventricular inflow pressures in normal subjects and patients with dilated cardiomyopathy. Reconstruction from pulsed Doppler echocardiography.
To estimate early diastolic left ventricular inflow pressures in normal subjects and patients with dilated cardiomyopathy, and thus to assess the potential effect of restoring forces. ⋯ (1) Total early diastolic positive and negative peak pressure drop are normally low, so that significant negative left ventricular pressures are not needed to explain normal resting early diastolic mitral flow velocities. (2) These low pressure drops are only possible with a large effective orifice area approaching end systolic left ventricular cavity area. (3) Atrioventricular pressure drops are much greater in dilated cardiomyopathy, where increased inflow accelerations are due to reduced effective flow orifice area. These disturbances will impair filling independently of any abnormality of relaxation or compliance.