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Relationship of simultaneous atrial and ventricular pressures in stage 16-27 chick embryos
1National Institutes of Health Specialized Center of Research in Pediatric Cardiovascular Diseases, Rochester, New York, USA.
Insights
Embryonic heart development involves balancing atrial and ventricular pressures. Increased pressure gradients in the atrioventricular orifice during development may affect ventricular filling and chamber shape.
Area of Science:
- Cardiovascular Physiology
- Developmental Biology
- Embryology
Background:
- Ventricular filling depends on atrial and ventricular function and load.
- Embryonic cardiovascular system growth and morphogenesis meet increasing metabolic demands.
- Atrial/ventricular coupling is crucial during primary cardiac morphogenesis.
Purpose of the Study:
- To define the relationship between simultaneous atrial and ventricular pressures.
- To investigate atrial/ventricular coupling during early cardiac development.
- To analyze pressure gradients in the embryonic chick heart.
Main Methods:
- Utilized servo-null micropressure systems to measure blood pressures.
- Recorded simultaneous atrial and ventricular pressures in white Leghorn chick embryos (stages 16-27).
- Digitally sampled analog waveforms at 500 Hz.
Main Results:
- Peak atrial pressure increased geometrically (0.38 to 1.21 mmHg).
- Ventricular end-diastolic pressure increased linearly (0.18 to 0.55 mmHg).
- Atrioventricular pressure gradients increased significantly by stage 27, indicating flow resistance.
Conclusions:
- The atrioventricular orifice and endocardial cushions act as a resistance site.
- This resistance influences both ventricular filling and cardiac chamber morphogenesis.
- Understanding these pressure dynamics is key to studying embryonic heart development.
Abstract:
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 16-27 white Leghorn chick embryo. We measured atrial and ventricular blood pressures with servo-null 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 and 0.20 +/- 0.03 mmHg at stage 16 to 0.52 +/- 0.10 and 0.62 +/- 0.11 mmHg at stage 27, respectively. The atrioventricular pressure gradients were similar for stages 16, 18, and 21, then increased to stage 27. This diastolic pressure gradient identifies the atrioventricular orifice and developing endocardial cushions as a site of flow resistance that may influence both ventricular filling and chamber morphogenesis.