Author + information
- Received May 22, 2014
- Revision received July 21, 2014
- Accepted July 28, 2014
- Published online February 1, 2015.
- Katelyn S. Fraser, MSc∗,
- George A. Heckman, MD, MSc∗,
- Robert S. McKelvie, MD, PhD†,
- Karen Harkness, RN, PhD†,
- Laura E. Middleton, PhD∗ and
- Richard L. Hughson, PhD∗∗ ()
- ∗Schlegel-University of Waterloo Research Institute for Aging, Faculty of Applied Health Sciences, Waterloo, Ontario, Canada
- †McMaster University and Hamilton Health Sciences, Hamilton, Ontario, Canada
- ↵∗Reprint requests and correspondence:
Dr. Richard L. Hughson, Schlegel-University of Waterloo Research Institute for Aging, Faculty of Applied Health Sciences, BMH 1101, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L3G1, Canada.
Objectives The purpose of this study was to examine cerebral blood flow (CBF) supine and during upright sitting in HF patients and control subjects to test the hypothesis that patients with HF will have a greater reduction in CBF from supine to seated compared with the control group.
Background Reduced CBF has been reported in patients with heart failure (HF). However, previous work has only examined CBF while supine, although an upright posture common to daily living may lead to further reductions.
Methods In 22 HF patients and 22 age- and sex-matched control subjects, continuous heart rate, mean arterial pressure, and end-tidal carbon dioxide readings were collected while supine and seated upright. Cardiac output was estimated from pulse contour analysis and was corrected for body size (cardiac index). The right internal carotid artery was imaged by using ultrasound to estimate CBF.
Results Heart rate increased less in response to the upright posture in HF patients versus control subjects (p = 0.006). Mean arterial pressure was unchanged, whereas end-tidal carbon dioxide decreased in response to position (p = 0.004) but did not differ between groups. Cardiac index was lower in patients with HF (p < 0.001) and decreased in both groups in response to the upright posture (p = 0.025), with a trend for a greater decrease in the HF group (p = 0.065). CBF decreased more in response to the upright posture in the HF group than in the control group (p = 0.007).
Conclusions The reduction in CBF was exaggerated in the upright posture in HF patients and may increase the risk for subsequent cognitive impairment.
The study was partially supported by a grant from the Canadian Institutes of Health Research (196261) to Drs. Hughson and Heckman. Dr. Heckman is Schlegel Research Chair in Geriatric Medicine at the University of Waterloo. Dr. Hughson is Schlegel Research Chair in Vascular Aging and Brain Health at the University of Waterloo. The authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- Received May 22, 2014.
- Revision received July 21, 2014.
- Accepted July 28, 2014.
- American College of Cardiology Foundation