title: 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.
authors.affiliation: Department of Cardiology, Westmead Hospital, Sydney NSW, Australia; Department of Cardiology, Auckland Hospital, Auckland, New Zealand.
authors.forename: Gnalini
authors.initials: G
authors.lastname: Sathananthan
authors.forename: Gunjan
authors.initials: G
authors.lastname: Aggarwal
authors.forename: Simmi
authors.initials: S
authors.lastname: Zahid
authors.forename: Karen
authors.initials: K
authors.lastname: Byth
authors.forename: William
authors.initials: W
authors.lastname: Chik
authors.forename: Daniel
authors.initials: D
authors.lastname: Friedman
authors.forename: Aravinda
authors.initials: A
authors.lastname: Thiagalingam
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D004562:Electrocardiography; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology; D011859:Radiography; D012189:Retrospective Studies
keywords: cardiac CT; cardiac axis; electrocardiogram