Aortic relative pressure components derived from four-dimensional flow cardiovascular magnetic resonance

Area of Science:

• Cardiovascular Imaging
• Biomedical Engineering
• Fluid Dynamics

Background:

• Relative aortic pressure is crucial for understanding cardiovascular health.
• Its spatiotemporal distribution and underlying components are not fully characterized.
• Advanced imaging techniques are needed to quantify these pressure dynamics.

Purpose of the Study:

• To assess the spatiotemporal distribution of relative aortic pressure.
• To quantify the magnitude of its three major components: transient, convective, and viscous.
• To investigate pressure variations in healthy volunteers and patients with aortic disease.

Main Methods:

• Four-dimensional (4D) flow cardiovascular magnetic resonance (CMR) imaging was performed on nine healthy volunteers and three patients with aortic disease.
• Spatiotemporal pressure maps were computed by solving the pressure Poisson equation from CMR flow fields.
• Pressure components were separated into time-varying inertial (transient), spatially varying inertial (convective), and viscous contributions.

Main Results:

• In healthy subjects, relative aortic pressure was primarily driven by transient effects (64.5%), followed by convective (13.6%) and viscous (0.3%) components.
• Regional analysis indicated prevalent convective effects in the Sinus of Valsalva and aortic arch during peak velocity.
• Patients with aortic disease showed altered peak transient values, duration, and localized convective changes linked to geometric abnormalities and complex flow patterns.

Conclusions:

• Evaluating the three components of relative aortic pressure provides mechanistic insights into aortic disease.
• This quantitative approach aids in understanding and stratifying aortic disease severity.
• The findings have potential implications for guiding future therapeutic strategies in aortic conditions.