External Counterpulsation Reduces Beat-to-Beat Blood Pressure Variability When Augmenting Blood Pressure and Cerebral Blood Flow in Ischemic Stroke.
OBJECTIVE
External counterpulsation (ECP) is a noninvasive method used to enhance cerebral perfusion by elevating the blood pressure in ischemic stroke. However, the response of the beat-to-beat blood pressure variability (BPV) in ischemic stroke patients during ECP remains unknown.


METHODS
We enrolled recent ischemic stroke patients and healthy controls. Changes in the blood flow velocities in bilateral middle cerebral arteries and the continuous beat-to-beat blood pressure before, during, and after ECP were monitored. Power spectral analysis revealed that the BPV included oscillations at very low frequency (VLF; <0.04 Hz), low frequency (LF; 0.04-0.15 Hz), and high frequency (HF; 0.15-0.40 Hz), and the total power spectral density (TP; <0.40 Hz) and LF/HF ratio were calculated.


RESULTS
We found that ECP significantly increased the systolic and diastolic blood pressures in both stroke patients and controls. ECP decreased markedly the systolic and diastolic BPVs at VLF and LF and the TP, and the diastolic BPV at HF when compared with baseline. The decreases in diastolic and systolic BPV reached 37.56% and 23.20%, respectively, at VLF, 21.15% and 12.19% at LF, 8.76% and 16.59% at HF, and 31.92% and 23.62% for the total TP in stroke patients, which did not differ from those in healthy controls. The change in flow velocity on the contralateral side was positively correlated with the total TP systolic BPV change induced by ECP (r=0.312, p=0.035).


CONCLUSIONS
ECP reduces the beat-to-beat BPV when increasing the blood pressure and cerebral blood flow velocity in ischemic stroke patients. ECP might be able to improve the clinical outcome by decreasing the beat-to-beat BPV in stroke patients, and this should be explored further in future studies.
Department of Medicine & Therapeutics, The Chinese University of Hong Kong, Hong Kong, China.
Ge
G
Tian
Department of Medicine & Therapeutics, The Chinese University of Hong Kong, Hong Kong, China.
Li
L
Xiong
Department of Medicine & Therapeutics, The Chinese University of Hong Kong, Hong Kong, China.
Wenhua
W
Lin
Department of Medicine & Therapeutics, The Chinese University of Hong Kong, Hong Kong, China.
Jinghao
J
Han
Department of Medicine & Therapeutics, The Chinese University of Hong Kong, Hong Kong, China.
Xiangyan
X
Chen
Department of Medicine & Therapeutics, The Chinese University of Hong Kong, Hong Kong, China.
Thomas Wai Hong
TW
Leung
Department of Medicine & Therapeutics, The Chinese University of Hong Kong, Hong Kong, China.
Yannie Oi Yan
YO
Soo
Department of Medicine & Therapeutics, The Chinese University of Hong Kong, Hong Kong, China. ks-wong@cuhk.edu.hk.
Lawrence Ka Sing
LK
Wong
blood pressure; blood pressure variability; cerebral hemodynamics; external counterpulsation; ischemic stroke