Cerebral blood flow, grey matter volumes, and autonomic nervous system function in heart failure

Heart failure (HF) patients show lateralized brain grey matter volume loss in autonomic nervous system (ANS) and cognitive regulatory structures, including insular cortices, cerebellum, and superior lateral frontal cortex. Cognition and ANS function are altered in HF, although relationships between these alterations and structural damage are unclear. Heart failure patients have lower cerebral blood flow (CBF) than do controls, which may contribute to perfusion deficits and structural damage. Many of the injured structures are perfused by the middle cerebral artery (MCA), which is accessible for study by transcranial Doppler procedures.; We examined lateralized cerebral vasomotor reactivity and cerebral blood flow velocity (CBFV). responses to a carbon dioxide (CO2) challenge, CBFV responses to ANS challenges (Valsalva maneuvers and orthostatic position changes), and brain structural injury relative to performance on cognitive tests in HF patients and controls. Subjects underwent a 3-minute hypercapnic and 1-minute hypocapnic phase for the CO2 challenge, three 16-second Valsalva maneuvers, and 3-minute periods in supine, sitting, and standing positions for orthostatic testing. Cognitive tests included the Mini-Mental State Exam, Trailmaking Test parts A & B (TMT-A & TMT-B), and Clock Drawing Test (CT). Brain structure injury was determined by magnetic resonance T2 relaxometry.; MCA vasomotor reactivity to CO2 challenges was impaired in HF, and CBFV was deficient at baseline on orthostatic maneuvers and to CO 2 and Valsalva challenges, preferentially on the right side; the laterality finding may reflect the largely right-sided neural injury in these patients. T2 relaxometry revealed neural injury related to abnormal cognitive scores on all tests, with relationships to damage most marked on the CT, less globally on the TMT-A, and the TMT-B test showing relationships only to isolated areas of damage.; The findings suggest a vascular basis for brain injury in HF patients, who may be at risk for further damage from impaired vascular responses to respiratory or other efforts analogous to the Valsalva maneuver, or to repeated alterations of CO2 levels, such as those occurring during sleep disordered breathing, an ancillary condition common in the syndrome. Pen and paper cognitive tests have limited value to show structural injury, with the CT most useful.