Mechanism of the increased ventilatory response to exercise in patients with chronic heart failure.

Abstract

Minute ventilation, respiratory rate, and metabolic gas exchange were measured continuously during maximal symptom limited treadmill exercise in 30 patients with stable chronic heart failure. The ventilatory response to exercise was assessed by calculation of the slope of the relation between minute ventilation and rate of carbon dioxide production. There was a close correlation between the severity of heart failure, determined as the maximal rate of oxygen consumption, and the ventilatory response to exercise.Reanalysis of the data after correction for ventilation of anatomical dead space did not significantly weaken the correlation but reduced the slope of the relation by approximately one third. These results show that the increased ventilatory response to exercise in patients with chronic heart failure is largely caused by mechanisms other than increased ventilation of anatomical dead space. This finding supports the concept that a significant pulmonary ventilation/ perfusion mismatch develops in patients with chronic heart failure and suggests that the magnitude of this abnormality is directly related to the severity of chronic heart failure.

Muscle sympathetic nerve activity and ventilation during exercise in subjects with and without chronic heart failure

“…Patients with HF also demonstrate an increased ventilatory response to exercise, ie, a steeper relationship between ventilation (VE) and carbon dioxide output (VCO2), reported as the VE/VCO2 slope (3)(4)(5). VE/VCO2 slope in HF correlates inversely with pVO2 (3,4). Both low pVO2 and increased VE/VCO2 slope identify chronic HF patients with more severe HF symptoms and higher mortality rates (6)(7)(8).…”

“…Their degree of exercise intolerance can be assessed by measuring peak oxygen uptake (pVO2) during incremental exercise testing (2). Patients with HF also demonstrate an increased ventilatory response to exercise, ie, a steeper relationship between ventilation (VE) and carbon dioxide output (VCO2), reported as the VE/VCO2 slope (3)(4)(5). VE/VCO2 slope in HF correlates inversely with pVO2 (3,4).…”

Mechanisms and Clinical Implications of Asymptomatic Mitral Regurgitation in Patients With Left Ventricular Dysfunction

“…21 During this test, the initial workload was set at 0 W and the intensity of exercise was increased by 1 W every 6 s. All patients were encouraged to perform maximal exercise. To evaluate changes of MR during exercise, 2 steady-state exercise tests were performed 1 week later.…”

Effects of Rehabilitation in Patients with Cardiac Disease

“…In patients with chronic heart failure this is considered an index to the severity of the disease and related to changes in ventilatory efficiency (Buller and Poole-Wilson 1990). Plots of VB (L/min) and VC~ (ml/kg/min) were drawn for each subject using all the data points from the exercise tests.…”