Influence of fetal respiratory movements on left atrial functional status.
OBJECTIVE
Because fetal respiratory movements increase left ventricular compliance, we hypothesized that the left atrial shortening fraction increases during fetal respiratory motions.


METHODS
A group of 26 normal fetuses with gestational ages between 28 and 38 weeks were assessed in a prospective cross-sectional study. Left atrial telesystolic and presystolic diameters were measured during apnea and after five consecutive respiratory movements. Left atrial shortening fraction was obtained by the ratio: [maximal left atrium diameter (telesystolic) - minimal left atrium diameter (presystolic)]/maximal left atrium diameter (telesystolic). The mean of three measurements were considered. Two-tailed Student's t-test was used.


RESULTS
Mean gestational age was (mean ± SD) 30.7 ± 2.8 weeks. Mean left atrial telesystolic diameter in apnea was 10.6 ± 0.7 mm and during respiratory movements it was 10.5 ± 1.1 mm (p = 0.98). Presystolic left atrial diameter was 5.2 ± 0.1 mm in apnea and 4.4 ± 1.3 mm during respiratory movements (p < 0.001). Left atrial shortening fraction was 0.50 ± 0.05 in apnea and 0.58 ± 0.13 during respiratory movements (p < 0.001).


CONCLUSIONS
Left atrial shortening fraction is higher during respiratory movements as a result of increased left ventricular compliance and consequent optimization of left atrial functional status.
Fundação Universitária de Cardiologia, Porto Alegre, RS, Brazil.
Maria de Fátima
Mde F
Monteiro Pereira Leite
Paulo
P
Zielinsky
Paulo Roberto
PR
Benchimol-Barbosa
Luiz Henrique
LH
Nicoloso
Stelamaris
S
Luchese
Antonio Luiz
AL
Piccoli
Alexandre Antonio
AA
Naujorks
D000293:Adolescent; D000328:Adult; D016279:Atrial Function, Left; D003430:Cross-Sectional Studies; D005260:Female; D005333:Fetus / Q000502:physiology*; D006801:Humans; D011247:Pregnancy; D011446:Prospective Studies; D012119:Respiration; D055815:Young Adult