Abstract 13904: Cerebral Blood Flow Changes During Intermittent Acute Hypoxia in Heart Failure Patients
Heart failure (HF) is associated with intermittent hypoxia, and the effects of this hypoxia on the cardiovascular system are not well understood. This study compared the effects of acute hypoxia (10% O2) between 14 chronic HF patients and 17 matched control group subjects. Carotid artery changes were examined during the first period of hypoxia, and brachial artery changes were examined during the second period of hypoxia. For each period of hypoxia, data were collected at baseline (B), after 2 minutes of hypoxia (H2), and after 4 minutes of hypoxia (H4). Plasma levels of norepinephrine, epinephrine, dopamine, and renin were measured at B and H4. In HF patients, there were significant increases between B and H4 in carotid artery blood flow (0.58±0.21 to 0.67±0.21 l.min-1.m-2; p=0.002), carotid artery systolic diameter (5.80±1.03 to 6.07±0.99 mm; p=0.045), and carotid artery diastolic diameter (5.52±1.01 to 5.76±0.96 mm; p=0.041), and there was a significant decrease between B and H4 in carotid artery resistance (175.67±76.58 to 147.07±59.02 mmHg/l.min-1.m-2; p=0.005). These changes were not observed in the control group. Hypoxia was not associated with changes in carotid artery compliance and distensibility, or with changes in brachial artery blood flow and diameter. The concentrations of sympathomimetic amines did not change in response to hypoxia in HF patients, but the norepinephrine level increased significantly between B and H4 in the control group. Minute ventilation increased, and O2 saturation and end-tidal CO2 concentration decreased, in response to hypoxia both groups. The changes in the carotid artery in response to hypoxia suggest an intensification of the compensatory mechanisms for preservation of cerebral blood flow in HF patients.
- © 2013 by American Heart Association, Inc.