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The foramen ovale is a hole in the atrial septum which allows blood from the right atrium to flow into the left atrium; after birth, the left atrium will be filled with blood returning from the lungs and the foramen ovale will close. The ductus arteriosus is a small, artery-like structure which allows blood to flow from the trunk of the ...
Dextrocardia situs ambiguus presents a surgical challenge not per se due to associated cardiac malformation, but because achieving adequate exposure is difficult. Right sided structures such as right atrium, right ventricle and tricuspid valve are oriented posteriorly in dextrocardia situs ambiguus (in contrast to dextrocardia with situs inversus).
Thus, oxygenated blood that recirculates back to the lungs can mix with blood that circulates throughout the body and can keep the body oxygenated until surgery can be performed. [5] Atrial septostomy can also be performed, usually with a cardiac catheter instead of surgery, to enlarge a natural connection between the heart's upper chambers ...
The intestines and other internal structures are also reversed from the normal, and the blood vessels, nerves, and lymphatics are also transposed. If the heart is swapped to the right side of the thorax, it is known as "situs inversus with dextrocardia" or "situs inversus totalis".
The clinical manifestations are similarly variable, depending on how the anatomical defects affect the physiology of the heart, in terms of altering the normal flow of blood from the RV and left ventricle (LV) to the aorta and pulmonary artery. For example: [citation needed]
A healthy heart has four chambers, each separated by valves that open and close to control blood flow between the chambers. When the heart beats, oxygen-poor blood enters the right atrium. The blood then flows into the right ventricle, where it pumps into the pulmonary artery to travel to the lungs for oxygen.
Blood enters the upper right atrium, is pumped down to the right ventricle and from there to the lungs via the pulmonary artery. [3] Blood going to the lungs is called the pulmonary circulation. [4] When the blood returns to the heart from the lungs via the pulmonary vein, it goes to the left side of the heart, entering the upper left atrium.
This switch in blood flow direction is precipitated by pulmonary hypertension due to increased pulmonary blood flow in a left-to-right shunt. The right ventricle hypertrophies to compensate for this pulmonary hypertension, so the right ventricular pressure becomes higher than the pressure in the left ventricle.