An in silico study of the effects of cardiovascular aging on carotid flow waveforms and indexes in a virtual population
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Published on: September 27, 2024
Irene Suriani1, R Arthur Bouwman1,2, Massimo Mischi1
1Eindhoven University of Technology, Eindhoven, The Netherlands.
Insights
Cardiovascular aging can be assessed using carotid ultrasound waveforms. The flow augmentation index (FAI) strongly indicates arterial stiffness and cardiovascular aging, aiding preventative care.
Area of Science:
- Cardiovascular Physiology and Aging
- Biomedical Engineering
- Medical Imaging and Diagnostics
Background:
- Cardiovascular aging accelerates disease risk and mortality.
- Lifestyle factors can exacerbate age-related arterial changes.
- Noninvasive assessment of cardiovascular aging is crucial for preventative strategies.
Purpose of the Study:
- To investigate the impact of aging on carotid waveform morphology and derived indices.
- To establish the clinical potential of carotid ultrasound for assessing cardiovascular aging.
- To correlate hemodynamic parameters with age-related vascular changes.
Main Methods:
- Generated an age-specific virtual population (VP) of 5,160 carotid hemodynamic waveforms using 1-D hemodynamic modeling.
- Validated the VP against in vivo aging trends from existing literature.
- Analyzed simulated waveforms in relation to age and underlying cardiovascular parameters.
Main Results:
- Carotid flow augmentation index (FAI) significantly increased with age (50% median increase) and strongly correlated with arterial stiffening (r=0.94).
- Carotid pulsatility index (PI) showed inverse correlation with reflection coefficient (r=-0.88) and direct correlation with forward wave energy (r=0.90).
- Corrected carotid flow time (ccFT) highly correlated with cardiac output (CO) (r=0.99), independent of vascular age.
Conclusions:
- Carotid waveforms are a promising tool for routine cardiovascular aging assessment.
- FAI is a robust indicator of local carotid stiffness and cardiovascular aging.
- Understanding waveform morphology aids in elucidating age-related hemodynamic changes.
Abstract:
Cardiovascular aging is strongly associated with increased risk of cardiovascular disease and mortality. Moreover, health and lifestyle factors may accelerate age-induced alterations, such as increased arterial stiffness and wall dilation, beyond chronological age, making the clinical assessment of cardiovascular aging an important prompt for preventative action. Carotid flow waveforms contain information about age-dependent cardiovascular properties, and their ease of measurement via noninvasive Doppler ultrasound (US) makes their analysis a promising tool for the routine assessment of cardiovascular aging. In this work, the impact of different aging processes on carotid waveform morphology and derived indexes is studied in silico, with the aim of establishing the clinical potential of a carotid US-based assessment of cardiovascular aging. One-dimensional (1-D) hemodynamic modeling was employed to generate an age-specific virtual population (VP) of N = 5,160 realistic carotid hemodynamic waveforms. The resulting VP was statistically validated against in vivo aging trends in waveforms and indexes from the literature, and simulated waveforms were studied in relation to age and underlying cardiovascular parameters. In our study, the carotid flow augmentation index (FAI) significantly increased with age (with a median increase of 50% from the youngest to the oldest age group) and was strongly correlated to local arterial stiffening (r = 0.94). The carotid pulsatility index (PI), which showed less pronounced age variation, was inversely correlated with the reflection coefficient at the carotid branching (r = -0.88) and directly correlated with carotid net forward wave energy (r = 0.90), corroborating previous literature where it was linked to increased risk of cerebrovascular damage in the elderly. There was a high correlation between corrected carotid flow time (ccFT) and cardiac output (CO) (r = 0.99), which was not affected by vascular age. This study highlights the potential of carotid waveforms as a valuable tool for the assessment of cardiovascular aging.NEW & NOTEWORTHY An age-specific virtual population was generated based on a 1-D model of the arterial circulation, including newly defined literature-based specific age variations in carotid vessel properties. Simulated carotid flow/velocity waveforms, indexes, and age trends were statistically validated against in vivo data from the literature. A comprehensive study of the impact of aging on carotid flow waveform morphology was performed, and the mechanisms influencing different carotid indexes were elucidated. Notably, flow augmentation index (FAI) was found to be a strong indicator of local carotid stiffness.
