Nilsson S
Department of Zoophysiology, University of Göteborg, Sweden.
Cardioscience. 1994 Sep;5(3):163-6.
The crocodilian heart is completely divided into two atria and two ventricles, resembling the arrangement in birds and mammals. However, in addition to the systemic aorta (right aorta, RAo) which emerges from the left ventricle, there is a second aorta (left aorta, LAo) that leaves the right ventricle beside the common pulmonary artery. The two aortae communicate immediately outside the valves through a small aperture, the foramen of Panizza. During diastole, the blood pressures in the RAo and LAo equalize through the foramen, and the pressure in the LAo therefore remains higher (under most circumstances) than that generated by the right ventricle preventing the LAo valve from opening. Blood flow in the LAo is biphasic, with a reversal of blood flow in systole due to the closure of the foramen of Panizza by the medial cusp of the RAo valve. Under these circumstances net LAo flow is low, and due solely to flow through the foramen. When peak systolic right ventricular pressure rises above that in the LAo, the valve will open, producing a (partial) pulmonary bypass (right-to-left shunt). This may occur during pulmonary vasoconstriction, or when the systemic (and hence the LAo) blood pressure decreases.
鳄鱼的心脏完全分为两个心房和两个心室，这与鸟类和哺乳动物的心脏结构相似。然而，除了从左心室发出的体主动脉（右主动脉，RAo）外，在肺动脉总干旁边还有一条从右心室发出的第二主动脉（左主动脉，LAo）。两条主动脉在瓣膜外侧通过一个小孔——潘氏孔立即相通。在舒张期，RAo和LAo中的血压通过该孔达到平衡，因此在大多数情况下，LAo中的压力仍然高于右心室产生的压力，从而阻止LAo瓣膜打开。LAo中的血流是双向的，在收缩期，由于RAo瓣膜的内侧瓣叶关闭潘氏孔，导致血流逆转。在这种情况下，LAo的净血流量很低，并且仅由于通过该孔的血流。当右心室收缩压峰值高于LAo中的压力时，瓣膜将打开，产生（部分）肺旁路（右向左分流）。这可能发生在肺血管收缩期间，或者当体循环（以及因此的LAo）血压下降时。
