Quantifying right atrial filling and emptying: A 4D-flow MRI study

Area of Science:

• Cardiovascular Imaging
• Hemodynamics
• Computational Fluid Dynamics

Background:

• Understanding blood flow dynamics in the right atrium (RA) is crucial for assessing cardiac function.
• Vortices are known to influence flow patterns and energy transfer in cardiovascular systems.
• Quantitative characterization of RA vortex formation is needed.

Purpose of the Study:

• To quantitatively characterize the central role of vortex formation on flow patterns and energy transfer within the right atrium (RA).
• To numerically derive vortex membership and analyze flow dynamics and energetics.
• To explore the potential application of this analytical approach to understanding right heart function.

Main Methods:

• Acquisition of 4D-flow magnetic resonance imaging (MRI) data in 12 healthy subjects at 3T.
• Classification of particles entering the RA based on origin.
• Numerical derivation of vortex membership using Q-criteria and assessment of flow dynamics and energetics.

Main Results:

• The majority of RA flow (74%) passes in a single beat; <1% is retained longer than two beats.
• A dominant vortex, comprising 79% of total flow, preserves kinetic energy and receives flow earlier.
• Nonvortex flow, entering during systole, traverses the RA via a direct path with shorter residence time and distance.

Conclusions:

• Blood flow momentum is preserved during systole within a dominant RA vortex.
• A semiautomated numerical approach can characterize this dominant vortex.
• This analytical method shows potential for understanding right heart function in health and disease.