Limitations to Exercise in Congestive Heart Failure: Insights from Peripheral and Transcranial Magnetic Stimulation
31st May 2008
Professor Michael Polkey
Professor John Moxham
Professor Andrew Coats
In patients with congestive heart failure (CHF) there is a mismatch between objective exercise tolerance and measures of ventricular function. The final limits to exercise tolerance and symptoms are centrally driven. A number of studies have documented structural and functional changes in the central nervous system (CNS) in patients with CHF.
To compare the behaviour of the CNS in patients with CHF and age-matched healthy controls.
A number of techniques were employed including: volitional and non-volitional invasive and non-invasive respiratory and peripheral muscle studies, lung function testing, cardiopulmonary exercise testing, transcranial magnetic stimulation and cortical evoked potentials in response to respiratory occlusion.
There is evidence of mild peripheral respiratory and quadriceps muscle weakness at rest in patients with CHF. Cycle exercise induces quadriceps, but not diaphragm fatigue in both healthy subjects and patients, but at lower workloads in patients. In healthy subjects there is a fall in cortical reactivity after exercise, but not in patients with CHF. Evoked potentials can be elicited in patients.
There is some evidence of change in central nervous system performance in patients with heart failure. Changes in peripheral muscle function are also noted at lower workloads