Mixing of Blood Going Out
A newborn may have truncus developed abnormally back when it was a developing fetus. In the beginning, there is one major blood vessel coming out of the heart. Then it is intended to split up so that the pulmonary artery, on the bottom right ventricle of the heart, separates itself into two arteries that carry oxygen-poor blood to each side of the lungs. Moreover, the bottom left ventricle has the aorta attached to it, which carries oxygen-poor blood to the body. Truncus arteriosus, or persistent truncus arteriosus, is the medical condition of the lone large blood vessel that doesn’t split during the development of the fetus. 
Persistent truncus arteriosus refers to the trunk (truncus) “persists.” The lone trunk is fastened to the heart and straddles the bottom chambers. Blood from both ventricles will mix with each other when forced out into the trunk. Infants have more difficult time breathing when the mixed blood with the more than normal amount directs back to the lungs. 
In regards to all the cases involving truncus arteriosus appearing in children, almost every single one of them also have ventricular septal defect (VSD). That congenital heart disorder involves a large hole emerging between the left and ventricles of the heart. 
All the abnormalities mentioned above happens as result of the blood of the children with truncus arteriosus doesn’t become oxygenated as it should be when it circulates through the body.
Increase Risk of Having Congenital Heart Defects
The exact cause of truncus arteriosus and other congenital heart defect is unknown. There are several elements that may increase the risk of a newborn having a heart condition. One element is taking certain medications during pregnancy. Another element is not being able to manage diabetes during pregnancy. The third element is being born with extra or defective chromosome that will cause certain chromosomal disorders. Such diseases are velocardiofacial syndrome, Down syndrome or DiGeorge’s syndrome. The last factor to mention is being infected with a viral illness such as rubella (German measles) during the early portion of the pregnancy. 
Problems Caused by Poor Circulation of Blood
Babies with truncus arteriosus usually have difficulties due to the blood being circulated improperly. They could have their heart receiving insufficient blood-related heart failure. Another possible problem is having high blood pressure in the lungs - pulmonary hypertension. The third problem to consider is the lungs drawing too much blood for the baby to properly breathe - respiratory problems. The last issue to inform is the baby’s heart working harder than usual because of increased blood flow through the heart and pulmonary hypertension. As a result, the heart will enlarge. Deliberately, the enlarged heart enfeebles. The medical term for heart enlargement is cardiomegaly.
I decided to write about truncus arteriosus because fellow Info Barrel writer Adrienne mentioned that her daughter has that heart defect on my more personal Tetralogy of Fallot article. Her comment inspired me to write about the condition so I could acquire some information about it.
Pediatric cardiologists help determines whether a patient has truncus arteriosus. The symptoms for it can resemble other medical conditions or heart problems. Hearing a heart murmur indicates a heart problem. The location within the chest that it is heard best, the loudness and quality of it (blowing, harsh, etc.) will assist the cardiologist which heart problem the patient may have. 
Tests to Perform for the Heart
There are other tests to perform for the cardiologist to study the results and determine which heart defect a patient has. The tests may include taking an x-ray of the chest, an echocardiogram (echo), an electrocardiogram (ECG or EKG), a cardiac MRI, a cardiac catheterization, or using a pulse oximetry. 
Treating Truncus Arteriosus with Prescription Medications
There are prescription medications for patients with truncus arteriosus to take so they can get assistance for their heart and lungs to work in a more desirable fashion. ACE (angiotensin-converting enzyme) inhibitors are taken to dilate the blood vessels to render it more conducive for the heart to pump blood forward into the body. Another medication a patient might take is diuretics. Those will help the kidneys to get rid of surplus fluid from the body, which can have an uneven water balance when the heart is not functioning well. To help make the heart muscle become stronger, Digoxin may be prescribed to have it pump more efficiently. 
Alternative Ways to Get Nutrients
Infants obviously needs adequate nutrition to grow. They may get tired when feeding if they suffer from truncus arteriosus. Thus, they may not get enough calories to gain weight. Giving infants either high-calorie formula or breast milk will have them intake the nutrients needed to grow. Furthermore, the formula or breast milk could be added with special nutritional supplements to augment the number of calories in each ounce. This will allow babies to drink less and consume ample calories to grow. Lastly, for the babies who are too tired to be bottle fed or can only drink part of it, they can receive their nutrients through a feeding tube. The tubes are pliable and tiny that goes through the nose, down the esophagus, and into the stomach.