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The thebesian circulation to developing conducting tissue: a nutrient-nodal hypothesis of cardiogenesis
1Health Sciences Centre, Winnipeg, Canada. John_Taylor@videon.wave.ca
Insights
The human heart
Area of Science:
- Cardiovascular Anatomy
- Embryonic Development
- Cardiac Physiology
Background:
- Previous research suggested retrograde sinusoidal blood flow to embryonic conducting tissue in the right atrium.
- The right atrial appendage's structure was implicated in this flow.
Purpose of the Study:
- To investigate the hypothesis that heart tissue nutrition, not downstream blood flow, drives the relationship between conducting, valvar, and trabecular myocardium.
- To examine the structure of junctional zones in outflow tracts for nutrient supply principles.
Main Methods:
- Gross and microscopic examination of human hearts (embryonic to adult).
- Investigation of a dedicated sinusoidal blood supply to the atrioventricular node.
- Review of outflow tract anatomy.
Main Results:
- A sinusoid-rich 'spongy trabecula' was found near the septal node.
- This suggests the septal junctional zone, like the sinoatrial, supports retrograde sinusoidal blood flow to nodal tissue.
- Outflow tract anatomy supports a repeating pattern of conducting, valvar, and trabecular structures.
Conclusions:
- The heart's structure prioritizes internal nutrient supply to conducting tissues.
- The findings support the concept of the heart functioning as an internal pump.
- Repeating structural triplets (conducting, valvar, trabecular) are key to cardiac nutrition.
Background:
In a previous paper the authors suggested that the right atrial appendage is structured for retrograde sinusoidal blood flow to embryonic conducting tissue in the venous sinus portion of the right atrium.
Objective:
To test the hypothesis that the relationship among conducting, valvar and trabecular myocardium of the human heart is primarily for the nutrition of the heart itself rather than for downstream blood flow.
Material And Methods:
Embryonic, fetal, infant and adult human hearts were studied grossly and microscopically for evidence of a dedicated sinusoidal blood supply to the atrioventricular node. Outflow tract anatomy was reviewed to test the hypothesis that junctional zones, nodal or non-nodal, are structured according to the same basic principle concerning nutrient supply to conducting tissue.
Conclusions:
The finding of a sinusoid-rich 'spongy trabecula' in relation to the septal node suggests that the septal junctional zone, like the sinoatrial junctional zone, is structured for retrograde sinusoidal blood flow to nodal conducting tissue. The anatomy of the pulmonary and aortic outflow tracts supports the idea that the heart is structured from repeating triplets of conducting, valvar and sinusoid-rich trabeculae. Although the heart is an external pump, it is structured as an internal pump.