Hemodynamic Responses in Carotid Bifurcation Induced by Enhanced External Counterpulsation Stimulation in Healthy Controls and Patients With Neurological Disorders.

Hui Wang,Junping Peng,Bin Deng,Yujia Wang,Huahui Liu,Bin Luo,Jianhang Du,Shuai Tian,Wei Pan,Xinghua Li,Yi Liang

doi:10.3389/fphys.2021.717080

Abstract

Enhanced external counterpulsation is a Food and Drug Administration–approved, non-invasive, assisted circulation therapy for ischemic cardiovascular and cerebrovascular diseases. Previous studies have confirmed that EECP stimulation induces largely different cerebral hemodynamic responses in patients with ischemic stroke and healthy controls. However, the underlying mechanisms remain uncertain. We hypothesize that different blood redistributions at the carotid bifurcation may play a key role. Ten subjects were enrolled in this study, namely, five patients with neurological disorders and five young healthy volunteers as controls. Magnetic resonance angiography (MRA) was performed on the carotid artery. All the subjects received a single session of EECP treatment, with external cuff pressures ranging from 20 to 40 kPa. Vascular ultrasound measurements were taken in the common carotid artery (CCA), external carotid artery (ECA) and internal carotid artery (ICA). Three-dimensional patient-specific numerical models were developed to calculate the WSS-derived hemodynamic factors. The results indicated that EECP increased CCA and ECA blood flow in both groups. The ICA blood flow in the patient group exhibited a mean increase of 6.67% during EECP treatment compared with the pre-EECP condition; a mean decrease of 9.2% was observed in the healthy control group. EECP increased the averaged wall shear stress (AWSS) throughout the carotid bifurcation in the patient group; the ICA AWSS of the healthy group decreased during EECP. In both groups, the oscillatory shear index (OSI) in the ICA increased proportionally with external cuff pressure. In addition, the relative resident time (RRT) was constant or slightly decreased in the CCA and ECA in both groups but increased in the ICA. We suggest that the benefits of EECP to patients with neurological disorders may partly result from blood flow promotion in the ICA and increase in WSS at the carotid bifurcation. In the healthy subjects, the ICA blood flow remained constant during EECP, although the CCA blood flow increased significantly. A relatively low external cuff pressure (20 kPa) is recommended as the optimal treatment pressure for better hemodynamic effects. This study may play an important role in the translation of physiological benefits of EECP treatment in populations with or without neurological disorders.

Highlights

Enhanced external counterpulsation is an FDA-approved atraumatic therapy that uses a non-invasive circulatory support device to improve blood perfusion in ischemic organs such as the heart and brain (Werner et al, 1999; Michaels et al, 2002; Lin S. et al, 2012)
This study investigates the blood flow redistribution characteristics of healthy subjects and patients with neurological disorders under external counterpulsation (EECP) stimulation to assess the variations in wall shear stress (WSS)-related factors such as AWSS, oscillatory shear index (OSI), and relative resident time (RRT)
For the healthy control group, EECP stimulation with cuff pressures of 20 and 30 kPa led to statistically significant increases in mean blood flow rate (MBFR) over a cardiac cycle in the common carotid artery (CCA) compared with the pre-EECP condition [7.339 ± 1.547 vs. 8.282 ± 1.497 ml/s (p = 0.034), and 7.339 ± 1.547 vs. 8.426 ± 1.595 ml/s (p = 0.017), respectively]

Summary

INTRODUCTION

Enhanced external counterpulsation is an FDA-approved atraumatic therapy that uses a non-invasive circulatory support device to improve blood perfusion in ischemic organs such as the heart and brain (Werner et al, 1999; Michaels et al, 2002; Lin S. et al, 2012). Werner et al (1999) reported a 19 and 26% blood flow volume increase during EECP in internal carotid arteries (ICAs) of healthy volunteers with 200 and 300 mmHg cuff pressure, respectively. The same research group further reported that EECP with a cuff pressure of 250 mmHg led to a plateau or relative decrease in blood flow velocities in the middle cerebral artery (MCA) both in healthy controls and patients with severe coronary atherosclerosis (Werner et al, 2003). This study investigates the blood flow redistribution characteristics of healthy subjects and patients with neurological disorders under EECP stimulation to assess the variations in WSS-related factors such as AWSS, oscillatory shear index (OSI), and relative resident time (RRT).

RESULTS AND DISCUSSION

LIMITATIONS

CONCLUSION

ETHICS STATEMENT