Electrocardiography-gated dual-source computed tomography in the detection of atrial septal aneurysm

Abstract

The aim of the current study was to investigate the atrial septal aneurysm (ASA) incidence rate and describe its morphologic features by dual-source computed tomography (DSCT). A total of 8,626 patients (4,284 men and 4,342 women) who underwent DSCT examinations were enrolled. The presence of ASA was defined as the protrusion of the complete or partial interatrial septum with a maximum vertical distance (MVD) from the atrial septum plane of >10 mm during a cardiac cycle and a diameter of the aneurysm base of >15 mm. The MVD and direction of the protrusion, as well as other abnormalities, were recorded. The ASA patients were classified by both gender and directions of protrusion into four groups, including the right atrium (RA) and left atrium (LA) groups in males and females, respectively. Values across groups were compared using the independent-sample t-test and differences in qualitative variables were assessed with the χ² test. Of the 8,626 patients, 51 (0.6%) were diagnosed with ASA (mean age, 62±10 years), including 23 (0.5%) males and 28 (0.6%) females. There were no significant differences in the age (t=-1.37, P>0.05) and incidence rate (χ²=0.43, P>0.05) between the male and female groups. However, there were significant differences in the mean ages (t=-2.20, P<0.05) and the gender proportions (χ²=7.39, P<0.05) of patients in the RA and LA groups. In the two male groups, no significant differences were observed in the diameters of the ASA bases and MVD in the RA and LA groups. In the female groups, the differences in the MVD of protrusion in RA and LA groups were non-significant, whereas the diameters of the base of ASA demonstrated significant differences (t=2.27, P<0.05). In conclusion, the ASA incidence rate was 0.6%, and electrocardiography-gated DSCT scan served as an alternative diagnostic technique for the detection of ASA. It is essential for radiologists to recognize this clinical entity and to minimize misdiagnoses and missed diagnoses.

Keywords: aneurysm; atrial septum; coronary angiography; multidetector computed tomography.

Figure 1.

Dual-source computed tomography with electrocardiography-gating in the axial multiplanar reconstruction view at 76% of the electrocardiogram R-R intervals (heart rate), demonstrating protrusion of interatrial septum into the right atrium (white arrow).

Figure 2.

Dual-source computed tomography with electrocardiography-gating in axial multiplanar reconstruction view at 33% of the electrocardiogram R-R intervals (heart rate), revealing protrusion of the interatrial septum into the left atrium (white arrow).

Figure 3.

Dual-source computed tomography images of the same patient at (A) 71% of the electrocardiogram R-R intervals (heart rate) showing protrusion of the interatrial septum into the right atrium, and (B) at 33% of the electrocardiogram R-R intervals (heart rate) presenting protrusion into the left atrium (white arrows).

Figure 4.

Dual-source computed tomography with electrocardiography-gating in axial multiplanar reconstruction view at 78% of the electrocardiogram R-R intervals (heart rate), revealing interatrial shunting through the foramen in the wall of the atrial septal aneurysm (white arrows).