Physiological characteristics of diameter pulses in the fetal descending aorta
Sindberg Eriksen, P.; Gennser, G.; Lindström, K.
Acta Obstetricia et Gynecologica Scandinavica 63(4): 355-363
1984
ISSN/ISBN: 0001-6349 PMID: 6741461 Document Number: 224934
The dynamic behavior in situ of the descending aorta in the human fetus was studied. The pulsatile movements of the vessel walls were recorded in 36 clinically normal fetuses using a real-time phase-locked ultrasonic system measuring echo movements with high spatial and temporal resolution. The mean amplitude of the diameter pulsations was similar in the 28th-35th wk to that in the 36th-40th wk but, as the apparent diastolic diameter increased, the pulse-elicited increment of the cross-sectional area was 29% larger in the older group. The diastolic diameter decreased (P < 0.001) and the amplitude of the diameter pulsation increased (P < 0.001) with prolongation of the previous beat interval. The diameter pulse velocity was positively correlated to gestational age (P < 0.001), ranging between 1.35 and 2.89 m/s. The incremental phase of the pulse curve diminished in duration with increasing distance from the heart (P < 0.001) and with decreasing duration of the previous beat interval (P < 0.001). The maximum slope of the incremental phase was higher in the more distal part of the aorta (P < 0.001). The diameter pulses contain useful information on the cariovascular dynamics and provide evidence that the Frank-Starling mechanism is effective also in the human fetus. [Reference data for further investigations on pathological pregnancies and on the influence of maternal smoking on fetal circulation are provided.].