Dynamic Anatomical Study Of Cardiac Shunting In Crocodiles Using High-Resolution Angioscopy

Axelsson, Michael, Franklin, Craig E., Lofman, Carl O., Nilsson, Stefan and Grigg, Gordon C. (1996) Dynamic Anatomical Study Of Cardiac Shunting In Crocodiles Using High-Resolution Angioscopy. Journal of Experimental Biology, 199 2: 359-365.

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Author Axelsson, Michael
Franklin, Craig E.
Lofman, Carl O.
Nilsson, Stefan
Grigg, Gordon C.
Title Dynamic Anatomical Study Of Cardiac Shunting In Crocodiles Using High-Resolution Angioscopy
Journal name Journal of Experimental Biology   Check publisher's open access policy
ISSN 0022-0949
Publication date 1996-02-01
Year available 1996
Sub-type Article (original research)
Open Access Status File (Author Post-print)
Volume 199
Issue 2
Start page 359
End page 365
Total pages 7
Place of publication United Kingdom
Publisher The Company of Biologists
Language eng
Subject 270503 Animal Anatomy and Histology
Abstract Prolonged submergence imposes special demands on the cardiovascular system. Unlike the situation in diving birds and mammals, crocodilians have the ability to shunt blood away from the lungs, despite having an anatomically divided ventricle. This remarkable cardiovascular flexibility is due in part to three anatomical peculiarities: (1) an 'extra' aorta (the left aorta) that leaves the right ventricle and allows the blood from the right ventricle to take an alternative route into the systemic circulation instead of going to the lungs; (2) the foramen of Panizza, an aperture that connects the right and left aortas at their base immediately outside the ventricle; and (3) a set of connective tissue outpushings in the pulmonary outflow tract in the right ventricle. Using high-resolution angioscopy, we have studied these structures in the beating crocodile heart and correlated their movements with in vivo pressure and flow recordings. The connective tissue outpushings in the pulmonary outflow tract represent an active mechanism used to restrict blood flow into the lungs, thus creating one of the conditions required for a right-toleft shunt. We observed that the foramen of Panizza was obstructed by the medial cusp of the right aortic valve during most of systole, effectively differentiating the left and right aortic blood pressure. During diastole, however, the foramen remained open, allowing pressure equilibration between the two aortas. Contrary to current theories, we found that the left aortic valves were unable to cover the foramen of Panizza during any part of the cardiac cycle, supporting the reversed foramen flow hypothesis. This would ensure a supply of blood to the coronary and cephalic circulation during a complete shutdown of the left side of the heart, such as might occur during prolonged submergence.
Keyword Crocodylus rhombifer
Crocodylus porosus
foramen of Panizza
blood flow
cog-teeth-like valves
right-to-left shunt
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Biological Sciences Publications
Ecology Centre Publications
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Citation counts: TR Web of Science Citation Count  Cited 21 times in Thomson Reuters Web of Science Article | Citations
Scopus Citation Count Cited 24 times in Scopus Article | Citations
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Created: Tue, 30 Nov 2004, 10:00:00 EST