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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).
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".
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 ...
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.
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.
The foramen ovale stays open because of the flow of blood from the right atrium to the left atrium. As the lungs expand, blood flows easily through the lungs and the membranous portion of the foramen ovale (the septum primum) flops over the muscular portion (the septum secundum). If the closure is incomplete, the result is a patent foramen ...
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]