Transposition of the great vessels:
Improper rotation of septation of the fetal truncus arteriosus results in the aorta arising from the right ventricle and the pulmonary artery arising from the left ventricle (Table 4.21). Hence, blood of low oxygen content is pumped to the aorta and right ventricle pressure is high. Moreover, the left ventricle receives oxygenated blood from the left atrium under low pressure and pumps blood of high oxygen content back to the lungs.
A communication(s) between the right ventricle and left ventricle must be present or quickly be produced for the newborn to survive. The communication can be an ASD, VSD, and/or a patent ductus arteriosus.
Deep cyanosis is usually observed, as well as mild congestive heart failure. Testing reveals right ventricle hypertension and enlargement. Echocardiography and catheterizations can be used to identify the great vessel origins and to demonstrate abnormal connections. If no septa are open, an emergency ASD can be created using an inflatable balloon catheter by which blood can get from one closed loop to the other. Dextrocardia may occur without transposition.
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