Is central nervous system processing altered in patients with heart failure?

Aims Breathlessness is a cardinal symptom of heart failure and the altered regulation of breathing is common. The contribution of abnormal central nervous system activity has not previously been investigated directly, although abnormal autonomic responses have been described. Our aim was to assess whether heart failure patients exhibit different patterns of regional brain activation after exercise stress. Methods We used positron emission tomography with H ₂¹⁵O, to measure changes in regional cerebral blood flow (rCBF) and absolute global cerebral blood flow (gCBF) in 6 male class II/III heart failure patients and 6 normal controls. Breathlessness (0-5 visual analogue scale) and respiratory parameters were measured at rest, after horizontal bicycle exercise and during isocapnic hyperventilation. CBF was measured in each condition in all subjects. Results Both groups were similarly breathless after exercise and the respiratory parameters were comparable. rCBF differences for the main comparison (exercise vs hyperventilation) were: activation of the right frontal medial gyrus (P