Computed tomography‐guided in vivo cardiac orientation and correlation with ECG in individuals without structural heart disease and in age‐matched obese and older individuals

Abstract

The cardiac axis in a structurally normal heart is influenced by a number of factors. We investigated the anatomical and electrical cardiac axes in middle-aged individuals without structural heart disease and compared this with age-matched obese and older individuals without structural heart disease. A retrospective study of controls included those between 30 and 60 years old with a normal body mass index (BMI), who were then compared with obese individuals between 30 and 60 years old and with individuals more than 60 years old with a normal BMI. The anatomical cardiac axis was determined along the long axis by cardiac computed tomography (CT) and correlated with the electrical cardiac axis on a surface electrocardiogram (ECG) in the frontal plane. A total of 124 patients were included. In the controls (n = 59), the mean CT axis was 38.1° ± 7.8° whilst the mean ECG axis was 51.8° ± 26.6°, Pearson r value 0.12 (P = 0.365). In the obese (n = 36), the mean CT axis was 25.1° ± 6.2° whilst the mean ECG axis was 20.1° ± 23.9°, Pearson r value 0.05 (P = 0.808). In the older group (n = 29), the mean CT axis was 34.4° ± 9.1° whilst the mean ECG axis was 34.4° ± 30.3°, Pearson r value 0.26 (P = 0.209). Obese individuals have a more leftward rotation of both axes than age-matched normals (P <0.0001), which could be secondary to elevation of the diaphragm. Older individuals have a more leftward rotation only of their electrical cardiac axis (P = 0.01), which could be a normal variant or reflect underlying conduction disturbances in this age group.

Anatomical cardiac and electrocardiographic axes correlate in both upright and supine positions: an upright/supine CT study

“…The ECG axis rotation (i.e., clockwise or counterclockwise rotation) was explained from the anatomical axis in two-thirds of rotation cases 19 . Engblom et al 7 used MRI to define the anatomical axis as the horizontal longitudinal axis and showed a weak correlation between the anatomical and QRS axes; however, other groups showed no correlation using MRI or CT 8 , 9 . Although the conclusions were transverse in these CT or MRI studies 6 – 9 , the cardiac axis was obtained from the apex to the center of the MV annulus (i.e.…”

“…Engblom et al 7 used MRI to define the anatomical axis as the horizontal longitudinal axis and showed a weak correlation between the anatomical and QRS axes; however, other groups showed no correlation using MRI or CT 8 , 9 . Although the conclusions were transverse in these CT or MRI studies 6 – 9 , the cardiac axis was obtained from the apex to the center of the MV annulus (i.e. MV-apex axis) in 2D cardiac long axis plane.…”

“…On the multiplanar reconstruction (MPR) images, the anatomical long axis of the left ventricle was defined as extending from the center of the annulus of the mitral valve (MV) to the apex (blue and yellow plane). Other MPR images of the aorta were reconstructed on the perpendicular line to the ST junction plane, and the ostium of the aorta was defined as the annulus of the atrial valve (AV) 7 , 9 , 32 (Supplemental Fig. 7 , 8 ).…”

“…Early investigators compared the QRS axis with the anatomical cardiac axis using chest radiography and found a correlation between them 1 – 4 . The development of non-invasive imaging enabled the acquisition of three-dimensional (3D) anatomy; thus, investigators were able to compare the anatomical axis on a two-dimensional (2D) plane obtained from magnetic resonance imaging (MRI) or computed tomography (CT) images 6 – 9 . However, these studies have yielded controversial results.…”

Radiographic anatomy of the heart of fruit bats

“…This posture can be influenced by the habit of bats hanging upside down so that adaptation occurs to the pericardial attachment, especially the apex to the diaphragm. Heart orientation in the thoracic cavity can affect the electric field of the heart on the surface of the body (Arteeva et al, 2005;Sathananthan et al, 2015).…”