Determination of left ventricular long-axis orientation using MRI: changes during the respiratory and cardiac cycles in normal and diseased subjects.
BACKGROUND
It has previously been shown that magnetic resonance imaging (MRI) can be used to accurately determine left ventricular (LV) long-axis orientation in healthy individuals. However, the inter- and intra-observer variability in patients with acute coronary syndrome (ACS) and chronic heart failure (CHF) has not been explored. Furthermore, the changes in LV long-axis orientation because of respiration and during the cardiac cycle remain to be determined.


METHODS
LV long-axis orientation was determined by MRI in the frontal and transverse planes in 44 subjects with no cardiac disease, 20 ACS patients and 13 CHF patients. Changes in LV long-axis orientation because of respiration were assessed in a subset of 25 subjects. Changes during the cardiac cycle were assessed in six subjects from each subject group. Reproducibility was assessed by a re-examination of 17 subjects after 28 days.


RESULTS
The inter- and intra-observer variability for LV long-axis orientation was low for all subject groups. The difference between the baseline and the 28 days examinations was -1.4+/-5.9 degrees and -0.8+/-4.4 degrees in the frontal and transverse planes, respectively. No significant change in LV long-axis orientation was found between end-expiration and end-inspiration (frontal plane, P=0.63 and transverse plane, P=0.42; n=25). No significant difference in change of the LV long-axis orientation during the cardiac cycle was found between the subject groups (frontal plane, chi-square 1.8, P=0.40 and transverse plane, chi-square 5.7, P=0.06).


CONCLUSIONS
There is a low inter-and intra-observer variability and a high reproducibility for determining LV long-axis orientation in patients with no cardiac disease as well as in patients with ACS or CHF. There is no significant change in LV long-axis orientation due to respiration, and only small changes during the cardiac cycle in these groups.
Foster
John E
JE
Glasgow Cardiac Magnetic Resonance Unit, Glasgow, Lanarkshire, UK. j.e.foster@clinmed.gla.ac.uk
Engblom
Henrik
H
Martin
Thomas N
TN
Wagner
Galen S
GS
Steedman
Tracey
T
Ferrua
Stefania
S
Elliott
Alex T
AT
Dargie
Henry J
HJ
Groenning
Bjoern A
BA
D000328:Adult; D002908:Chronic Disease; D004562:Electrocardiography / Q000379:methods; D005260:Female; D006321:Heart / Q000502:physiology* / Q000503:physiopathology; D006333:Heart Failure / Q000503:physiopathology*; D006352:Heart Ventricles / Q000033:anatomy & histology*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D012016:Reference Values; D015203:Reproducibility of Results; D012143:Respiratory Physiological Phenomena; D016277:Ventricular Function, Left / Q000502:physiology*