# Evaluation of the volume and function of the right atrial appendage using computed tomography

## TL;DR

This study uses CT scans to measure the size and function of the right atrial appendage in patients with normal heart rhythms, finding differences between males and females and correlations with body size.

## Contribution

The study introduces a method using 256-slice CT angiography to evaluate the dynamic volume and function of the right atrial appendage in sinus rhythm patients.

## Key findings

- Male patients had significantly larger RAA and RA volumes than females.
- RAA volume showed minimal fluctuation during 65–85% of the cardiac cycle, indicating a resting phase.
- RAAVmax and RAAVmin correlated with weight, body surface area, and RA volumes but not with height.

## Abstract

To assess the volume and function of the right atrial appendage (RAA) in patients with sinus rhythm using 256-slice spiral computed tomography (CT) angiography.

A total of 60 patients with normal cardiac CT imaging features were enrolled in this retrospective study. The raw imaging data were used to reconstruct 3D images, which were analyzed to measure the volume of the RAA and right atrium (RA) throughout the cardiac cycle, and to obtain the maximum and minimum volume of the RAA and RA (RAAVmax, RAAVmin and RAVmax, RAVmin). Additionally, the RAA ejection volume (RAAEV), RAA ejection fraction (RAAEF), RA ejection volume (RAEV), and ejection fraction (RAEF) were calculated. Independent sample t-tests were used to analyze the data of the RAA and RA between male and female groups. Pearson correlation analysis was used to analyze the correlation between RAA parameters, RA parameters and basic physiological parameters of the human body.

The volumes of the RAA and RA constantly changed throughout the cardiac cycle, characterized by similar curves and two emptying phases. During 65–85% of the cardiac cycle, the volume of RAA exhibited a minimal fluctuation, indicating a resting state. Male patients had significantly (P < 0.05) greater values than female in the RAAVmax, RAAEV, RAVmax, and RAVmin(P = 0.003, P = 0.001, P = 0.031 and P = 0.025, respectively). RAAVmax correlated with the patient’s weight, body surface area (BSA), RAVmax, RAVmin and RAAVmin (r = 0.434 P = 0.001, r = 0.363 P = 0.004, r = 0.331 P = 0.010, r = 0.352 P = 0.006 and r = 0.858 P = 1.9485E-18, respectively), but did not significantly correlated with height. RAAVmin positively correlated with the weight, BSA, RAVmax, and RAVmin (r = 0.434 P = 0.011, r = 0.363 P = 0.035, r = 0.331 P = 0.006, and r = 0.352 P = 0.000368, respectively), but did not significantly correlated with height. Additionally, RAAEV correlated with weight, BSA, RAAVmax, and RAAVmin (r = 0.426 P = 0.001, r = 0.356 P = 0.005, r = 0.885, P = 5.9452E-21 and r = 0.521 P = 0.00020, respectively). RAAEF showed a negative correlation with both RAAVmin and RAVmin (r=–0.478 P = 0.000112 and r=–0.289 P = 0.025, respectively).

CT angiography with multi-phase three-dimensional volume reconstruction is very helpful in evaluating the volume and function of RAA, providing an important guidance for diagnosis and treatment of cardiac diseases.