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Blood–wall fluttering instability as a physiomarker of the progression of thoracic aortic aneurysms


The diagnosis of aneurysms is informed by empirically tracking their size and growth rate. Here, by analysing the growth of aortic aneurysms from first principles via linear stability analysis of flow through an elastic blood vessel, we show that abnormal aortic dilatation is associated with a transition from stable flow to unstable aortic fluttering. This transition to instability can be described by the critical threshold for a dimensionless number that depends on blood pressure, the size of the aorta, and the shear stress and stiffness of the aortic wall. By analysing data from four-dimensional flow magnetic resonance imaging for 117 patients who had undergone cardiothoracic imaging and for 100 healthy volunteers, we show that the dimensionless number is a physiomarker for the growth of thoracic ascending aortic aneurysms and that it can be used to accurately discriminate abnormal versus natural growth. Further characterization of the transition to blood–wall fluttering instability may aid the understanding of the mechanisms underlying aneurysm progression in patients.

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Fig. 1: Model of a distensible blood vessel.
Fig. 2: The marginal stability curve \(\tilde{\mu }=0\) as a function of the dimensionless wavenumber k of the perturbation mode and the dimensionless number Nω.
Fig. 3: Flutter instability parameter spatially resolves and temporally predicts abnormal aortic growth.
Fig. 4: The distribution of the aneurysm physiomarker Nω,sp in the patient (n = 117) and normal participant (n = 100) cohorts.

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Data availability

The main data supporting the findings of this study are available within the paper and its Supplementary Information. The raw clinical data in the study are too large to be publicly shared, yet they are available for research purposes from co-author M.M. on reasonable request.

Code availability

Codes for the collection and analysis of data are available on request.


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Research reported in this publication was supported by the National Heart, Lung, and Blood Institute of the National Institutes of Health under award number F32HL162417. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

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Conceptualization—N.A.P. and T.Y.Z.; planning and supervision—N.A.P., M.M., T.Y.Z. and E.M.I.J.; theoretical analysis—N.A.P. and T.Y.Z.; clinical methodology—M.M., E.M.I.J., B.D.A., T.Y.Z., S.H., B.C.S. and G.E.; writing—N.A.P., M.M., T.Y.Z., G.E., E.M.I.J. and S.H.

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Correspondence to Tom Y. Zhao or Neelesh A. Patankar.

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Zhao, T.Y., Johnson, E.M.I., Elisha, G. et al. Blood–wall fluttering instability as a physiomarker of the progression of thoracic aortic aneurysms. Nat. Biomed. Eng 7, 1614–1626 (2023).

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