II. The Normal Left Atrial Volume in Man
Maximum and minimum volumes of the left atrium (LA) were calculated from the biplane angiocardiograms of 18 men and four women without significant heart disease.
The mean LA maximum volume was 63 cc ± 16 cc; the mean LA minimum volume was 31 cc±10 cc, and their difference, LA cyclic volume change, was 33 cc±13 cc. Larger LA volumes were associated with greater cyclic volume changes. LA cyclic volume changes constituted 38% of LV stroke volume.
No significant correlation between LA volumes and age, sex, surface area, heart rate, LV end-diastolic volume, LV stroke volume, or cardiac output was found.
Volume data in normal subjects support the thesis that the LA serves mainly as a reservoir and conduit for blood destined for the left ventricle and that its contractile function is less important. The relation of LA volume change to LV stroke volume appears abnormal in chronic mitral regurgitation and constrictive pericarditis.
- © 1968 American Heart Association, Inc.