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Retrograde aortic blood flow as a mechanism of stroke: MR evaluation of the prevalence in a population-based study

  • Andreas HarloffEmail author
  • Paul Hagenlocher
  • Thomas Lodemann
  • Anja Hennemuth
  • Cornelius Weiller
  • Jürgen Hennig
  • Werner Vach
Magnetic Resonance

Abstract

Objectives

Retrograde blood flow from complex atheroma in the descending aorta (DAo) has only recently been described as a potential mechanism of stroke. However, prevalence of this mechanism in the general population and the exact factors influencing stroke risk are unclear.

Methods

One hundred twenty-six consecutively recruited inhabitants of Freiburg, Germany, between 20 and 80 years of age prospectively underwent 3-T MRI. Aortic plaque location and thickness were determined by 3D T1 MRI (1 mm3). 4D flow MRI (spatial/temporal resolution 2 mm3/20 ms) and dedicated software were used to determine prevalence and extent of flow reversal and potential embolization from DAo plaques. Flow was correlated with baseline characteristics and echocardiographic and MRI parameters (aortic diameter, wall thickness, and pulse wave velocity).

Results

The maximum length of retrograde blood flow connecting the DAo with the left subclavian artery (LSA) increased from 16.1 ± 8.3 mm in 20–29-year-old to 24.7 ± 11.7 mm in 70–80-year-old subjects, correlated with age (r = 0.37; p < 0.001), and was lower in females (p = 0.003). Age was the only independent predictor of increased flow reversal. Complex DAo plaques ≥ 4-mm thickness were found in eight subjects (6.3%) and were connected with the LSA, left common carotid artery, and brachiocephalic trunk in 8 (100%), 1 (12.5%), and 0 (0%) cases, respectively.

Conclusions

Retrograde blood flow from the DAo was very frequent. However, potential retrograde embolization was rare due to the low incidence of complex DAo plaques. The magnitude of flow reversal and prevalence of complex atheroma increased with age. Thus, older patients with aortic atherosclerosis are especially vulnerable to this stroke mechanism.

Key Points

4D flow MRI allows in vivo visualization and quantification of individual and three-dimensional blood flow patterns within the thoracic aorta including retrograde components.

This population-based study showed that blood flow reversal from the proximal descending aorta to the brain-supplying great arteries is very frequent and able to reach all brain territories. The extent of such flow reversal increases with age and with the extent of aortic atherosclerosis.

The combination of blood flow reversal with plaque rupture in the proximal descending aorta constitutes a potential stroke mechanism that should be considered in future trials and in the management of stroke patients in clinical routine.

Keywords

Magnetic resonance imaging Angiography Atherosclerosis Embolism Thoracic aorta 

Abbreviations

AAo

Ascending aorta

BCT

Brachiocephalic trunk

LCCA

Left common carotid artery

DAo

Descending aorta

GRAPPA

Generalized autocalibrating partial parallel acquisition

LSA

Left subclavian artery

PEAK

Parallel MRI with extended and averaged GRAPPA kernels

PWV

Pulse wave velocity

TTE

Transthoracic echocardiography

Notes

Acknowledgements

The authors thank Adriana Komancsek for performing MRI examinations and Dr. Konrad Whittaker for proof reading of the manuscript.

Funding

Prof. Dr. Andreas Harloff received funding from Deutsche Forschungsgemeinschaft (DFG), Bonn, Germany, grant no. HA5399/3-1.

Compliance with ethical standards

Guarantor

The scientific guarantor of this publication is Prof. Dr. Andreas Harloff.

Conflict of interest

The authors of this manuscript declare no relationships with any companies, whose products or services may be related to the subject matter of the article.

Statistics and biometry

One of the authors, Prof. Dr. Werner Vach, has significant statistical expertise and performed statistical analysis.

Informed consent

Written informed consent was obtained from all subjects in this study.

Ethical approval

Institutional Review Board approval was obtained.

Study subjects or cohorts overlap

Data from this population-based study were analyzed and published. In these three articles, aortic pulse wave velocity, hemodynamics of the right heart, and hemodynamics of the pulmonary arteries were investigated.

Accordingly, there is only minimal overlap with the submitted paper focussing on the extent of retrograde blood flow and potential retrograde embolization from the descending aorta:

Harloff A, Mirzaee H, Lodemann T, Hagenlocher P, Wehrum T, Stuplich J, Hennemuth A, Hennig J, Grundmann S, Vach W. Determination of aortic stiffness using 4D flow cardiovascular magnetic resonance - a population-based study. J Cardiovasc Magn Reson. 2018 Jun 21;20(1):43.

Wehrum T, Lodemann T, Hagenlocher P, Stuplich J, Ngo BTT, Grundmann S, Hennemuth A, Hennig J, Harloff A. Age-related changes of right atrial morphology and inflow pattern assessed using 4D flow cardiovascular magnetic resonance: results of a population-based study. J Cardiovasc Magn Reson. 2018 Jun 14;20(1):38.

Wehrum T, Hagenlocher P, Lodemann T, Vach W, Dragonu I, Hennemuth A, von Zur Mühlen C, Stuplich J, Ngo BT, Harloff A. Age dependence of pulmonary artery blood flow measured by 4D flow cardiovascular magnetic resonance: results of a population-based study. J Cardiovasc Magn Reson. 2016 May 31;18(1):31.

Methodology

• prospective

• cross-sectional study/observational

• performed at one institution

Supplementary material

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Copyright information

© European Society of Radiology 2019

Authors and Affiliations

  • Andreas Harloff
    • 1
    • 2
    Email author
  • Paul Hagenlocher
    • 1
    • 2
  • Thomas Lodemann
    • 1
    • 2
  • Anja Hennemuth
    • 3
  • Cornelius Weiller
    • 1
    • 2
  • Jürgen Hennig
    • 2
    • 4
  • Werner Vach
    • 5
    • 6
  1. 1.Department of Neurology and Neurophysiology, Medical CenterUniversity of FreiburgFreiburgGermany
  2. 2.Faculty of MedicineUniversity of FreiburgFreiburgGermany
  3. 3.Institute for Cardiovascular Computer-Assisted MedicineCharité - Universitätsmedizin BerlinBerlinGermany
  4. 4.Department of Diagnostic RadiologyMR Physics, Medical Center - University of FreiburgFreiburgGermany
  5. 5.Institute for Medical Biometry and Statistics, Medical Faculty and Medical CenterUniversity of FreiburgFreiburgGermany
  6. 6.Department of Orthopaedics and TraumatologyUniversity Hospital BaselBaselSwitzerland

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