Abstract 1338: Brain MRI Neural Responses to Hand-Grip in Heart Failure
Heart failure (HF) patients show impaired neural responses to autonomic challenges, possibly from injury to autonomic control brain sites. The insular cortex (right-side, sympathetic, left parasympathetic) is injured in HF and may show abnormal autonomic neural responses to motor challenges, such as hand-grip.
METHODS: Functional magnetic resonance imaging (fMRI) signals were assessed over discrete insular regions to hand-grip in 15 HF (age 53±8; 10 male; LVEF 28±7%) and 45 controls (age 51±7; 28 males). Subjects squeezed an inflated bag with their right hand for a 16 sec period, repeated 4 times at one min intervals. Brain volumes were collected at 2 sec intervals with a 3.0 Tesla scanner and images were preprocessed with SPM5. Time trends of brain signals were extracted over 5 left and right insular regions and patterns compared between groups.
RESULTS: A significant muting of signals and loss of recovery response in all areas of the insular cortex on both right and left sides appeared in HF over controls (Fig. 1⇓). Unlike other autonomic challenges (e.g., Valsalva), no response phase differences emerged. Left side early responses in posterior insular areas in HF were less affected than the right.
CONCLUSIONS: Both left and right insular cortices show significantly impaired fMRI signal responses to hand-grip in HF, with posterior left-sided (parasympathetic) areas less affected in early response stages. Impaired autonomic actions to motor challenges could significantly affect both sympathetic and parasympathetic responses to motor behavior. Failed recovery responses will significantly affect autonomic patterns to successive challenges.