Relationship of simultaneous atrial and ventricular pressures in
the stage 16 to 27 chick embryo.
Hu, Norman, and Bradley B. Keller.
NIH SCOR in Pediatric Cardiovascular Diseases, Strong Children's
Research Center, Department of Pediatrics, Box 631, University of
Rochester School of Medicine & Dentistry, 601 Elmwood Avenue,
Rochester, New York
APStracts 2:0229H, 1995.
Ventricular filling is determined by a dynamic balance between atrial
and ventricular load and function. The embryonic cardiovascular
system undergoes simultaneous growth and morphogenesis at the
cellular, tissue, and organ levels to match the embryo's
geometrically increasing metabolic demands. As part of our long-term
investigation of atrial/ventricular coupling during primary cardiac
morphogenesis, we defined the relationship between simultaneous
atrial and ventricular pressures in the stage 16 to 27 white Leghorn
chick embryo. We measured atrial and ventricular blood pressures with
servonull micropressure systems, and sampled analog waveforms
digitally at 500 Hz. Peak atrial pressure increased geometrically
from 0.38+/-0.03 to 1.21+/-0.17 mmHg, while ventricular end-diastolic
pressure increased linearly from 0.18+/-0.03 to 0.55+/-0.04 mmHg. The
passive and active mean pressure gradients increased from 0.23+/-0.04
mmHg and 0.20+/-0.03 mmHg at stage 16 to 0.52+/-0.10 mmHg and 0.62+/
-0.11 mmHg at stage 27, respectively. The atrioventricular (AV)
pressure gradients were similar for stages 16, 18, and 21, then
increased to stage 27. This diastolic pressure gradient identifies
the AV orifice and developing endocardial cushions as a site of flow
resistance that may influence both ventricular filling and chamber
morphogenesis.
Received 31 January 1995; accepted in final form 22 May 1995.
APS Manuscript Number H89-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 8 June 1995.