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The heart is the first functioning organ in the embryo and provides blood flow during cardiac morphogenesis from a muscle-wrapped tube a few cells thick to the four-chambered pump. We described the hemodynamics of the chick embryo from stage 12 (50 hours of a 21-day incubation) to stage 29 (6 days), during which the embryo weight increased 120-fold. We measured ventricular, embryo and extraembryonic vascular bed wet weights, dorsal aortic blood flow with a directional pulsed-Doppler velocity meter, and ventricular and vitelline arterial blood pressures with a servo-null micropressure system. The data are reported as mean +/- SEM. With rapid development and morphogenesis, dorsal aortic blood flow increased from 0.015 +/- 0.004 to 2.40 +/- 0.20 mm3/sec parallel to the geometric increase of wet embryo weight from 2.22 +/- 0.10 to 267.5 +/- 9.7 mg. Dorsal aortic blood flow normalized for embryo and extraembryonic weight remained relatively constant (Y = 2.13 + 0.02X, r = 0.23, SEE = 0.03). Stroke volume increased from 0.01 +/- 0.003 to 0.69 +/- 0.03 mm3, and heart rate doubled from 103 +/- 2 to 208 +/- 5 beats/min. Systolic, diastolic, and mean vitelline arterial pressure increased linearly from 0.32 +/- 0.01, 0.23 +/- 0.01, and 0.28 +/- 0.01 mm Hg at stage 12 to 2.00 +/- 0.06, 1.22 +/- 0.03, and 1.51 +/- 0.04 mm Hg, respectively, at stage 29. Ventricular peak systolic and end-diastolic pressure increased from 0.95 +/- 0.04 and 0.24 +/- 0.02 at stage 12 to 3.45 +/- 0.10 and 0.82 +/- 0.03 at stage 29, respectively. The hemodynamic waveforms were similar to those found in the four-chamber heart of the mature animal. These data are integral to understanding the interrelation of function and form during cardiac development.

Hemodynamics of the stage 12 to stage 29 chick embryo.