Truncus Arteriosus and Coarctation of the Aorta

Truncus arteriosus is a rare congenital heart condition in which a single blood vessel leads out of the hearts right and left ventricles, rather than the normal two vessels. Under normal circulation of blood, the aorta emerges from the left ventricle while the pulmonary artery leads out of the right ventricle. In the case of Truncus arteriosus, only one artery emerges from the ventricles. Coarctation of the aorta is the narrowing of this blood vessel that delivers blood rich in oxygen from the heart to other parts of the body. This condition is also congenital, and the heart is forced to pump harder in order to allow blood to flow through the narrowed part of the artery. Truncus arteriosus and coarctation of the aorta often occur together.

An adverse effect of truncus arteriosus is that blood rich in oxygen that should be pumped to other parts of the body and that without oxygen that should be directed to the lungs are mixed up. This situation causes severe circulatory complications. The condition can be fatal if not treated. Surgery to correct the anomaly is usually successful, particularly if it is did while the infant is less than one month old. Telltale signs of Truncus arteriosus include cyanosis (blue skin color), rapid breathing, shortness of breath, a pounding heart, poor feeding, poor growth, and excessive sleepiness.

Symptoms of aortic coarctation usually depend on how severe the condition is. Most sufferers do not display any signs. Children with a serious variation of aortic coarctation may exhibit symptoms early in life, although mild cases may not get diagnosed until they are adults. Symptoms may also be similar to those of other heart conditions that occur alongside this defect. Infants with a severe case of aortic coarctation may start showing symptoms immediately after birth. They include a pale skin, excessive sweating, irritability, and difficulties in breathing and feeding. If coarctation of the aorta in infants is not treated, is cause heart failure or even death.

Older children and grownups with aortic coarctation often do not exhibit symptoms as the narrowing of their artery is may not be that severe. For those whose symptoms emerge after infancy, they will most likely have high blood pressure in their arms although it would be lower in legs. Notable symptoms for this group include hypertension, muscle weaknesses, headaches, cold feet or leg cramps, chest pains, shortness of breath, fainting, and nosebleeds. All in all, displaying these symptoms does not necessarily mean an individual has a serious case of aortic coarctation. However, its better to have them checked immediately as early detection and treatment can prevent death.

Truncus arteriosus occurs when the heart of a fetus is developing, meaning that it is present when the baby is born. In most cases, what causes the defect is unknown. To understand the defects associated with truncus arteriosus, it is worth looking at the structure and function of a healthy heart. The heart has four chambers whose valves control blood flow by opening and closing in way that the liquid flows in one direction. The upper right chamber called the right atrium receives blood containing little oxygen from the body and pumps it to the right ventricle. The lower right chamber, which is the right ventricle, delivers the blood via the pulmonary artery to the lungs where it is injected with oxygen. The upper left chamber called the left atrium receives blood rich in oxygen from the lungs and pumps it to the left ventricle. The lower left chamber i.e. the left ventricle, delivers this blood to other parts of the body via the aorta.

The formation and development of a fetus heart is a rather complex process. All fetuses have, at one point, a single vessel known as truncus arteriosus that leaves the heart. However, as the heart undergoes normal development, the vessel splits into two parts. One of them ends up as the aortas lower portion linked to the left ventricle. The other becomes the pulmonary arterys lower portion linked to the right ventricle. It is also during this process that the two ventricles separate into a couple of chambers divided by a wall.

In the case of a newborn baby suffering from truncus arteriosus, the single vessel does not complete the process of splitting into separate vessels. Also, the wall that separates the ventricles does not close fully. This results in one blood vessel emerging from the heart as well as a hole in between the chambers; a condition referred to as ventricular septal defect. Together with the main defects associated with truncus arteriosus, the valves that controls flow of blood from the ventricles to the vessel is often defective. Such a situation causes a backflow of blood into the heart.

The exact cause of aortic coarctation is not clear. Mild or severe narrowing in a certain part of the aorta occurs due to unknown reasons. Although the defect can occur at any place along the artery, it is mostly found near a blood vessel known as the ductus arteriosus. It generally starts before the baby is born, with congenital heart conditions being the most commonly occurring birth defects. On rare occasions, aortic coarctation develops in other times apart from before birth. For instance, it can be caused by a traumatic injury. Also, the aorta can be narrowed by atherosclerosis (severe artery hardening) or by Takayasus arteritis (a condition that causes inflamed arteries.

Aortic coarctation is usually found in front of the blood vessels that move to the lower body and behind those that branch towards the upper body. Such a situation can often result in high blood pressure in the arm while legs and ankles experience low pressure. The condition causes the left ventricle to strain a lot in pumping blood through the narrowed artery, thus causing an increase in blood pressure to this heart chamber. It may cause hypertrophy whereby the chambers wall thickens.

Although the exact cause of truncus arteriosus and other congenital heart conditions is unknown, there are a number of factors that can increase the chances of giving birth to a baby with a defect. If a female contracts a viral illness such as German measles during early pregnancy, it increases the risk of her baby being born with a heart defect. Also, failure to manage diabetes well during pregnancy can increase the chances of heart birth effects. Some medications are not recommended for pregnant women due to risks posed to the fetus. Children with chromosomal disorders such as velocardiofacial syndrome and DiGeorge's syndrome have a higher chance of truncus arteriosus. In addition, smoking while pregnant increases the risk of giving birth to a baby with a heart condition.

Coarctation of the aorta occurs more commonly in males than in females. It often occurs alongside other congenital heart conditions, although it is not known causes them to form together. An individual has a higher chance of getting aortic coarctation if he or she has an existing heart condition. The hearts left ventricle is separated from the aorta by the aortic valve. Most people with aortic coarctation have a bicuspid aortic that has two flaps rather than three. Prior to birth, a blood vessel known as the ductus arteriosus links the aorta with the left pulmonary artery in a way that allows blood bypass the lungs. This vessel usually closes shortly after the baby is born. Should it fail to close, it causes a condition known as a patent ductus arteriosus.

The irregular heart structures of someone with truncus arteriosus lead to severe blood circulation problems. Since the ventricles are not separated and blood leaves the heart from one vessel, blood rich in oxygen tends to mix with that containing little oxygen. This situation results in blood with insufficient oxygen flowing through the body. Complications arising from truncus arteriosus include respiratory problems. The irregular distribution of blood leads to excessive amounts moving into the lungs. Too much fluid inside the lungs would make the baby have difficulties in breathing. Pulmonary hypertension is another complication related to the heart condition. More blood flowing to the lungs narrows the lungs blood vessels. This raises blood pressure inside the lungs in a way that makes it rather difficult for the heart to deliver blood to the lungs.

Pulmonary hypertension together with the increasing flow of blood through the heart strains the hearts working pace in a manner that enlarges it. An enlarged heart will slowly weaken. The insufficient oxygen supply together with the extra workload also weakens the heart. The two factors can lead to heart failure, which is the inability to supply sufficient blood to the body. Even if the heart undergoes a successful surgery, there are other complications linked to truncus arteriosus likely to occur later in life. They include leaking heart valves, recurring pulmonary hypertension, disturbances in heart rhythm, and problems arising from the previous operation.

If aortic coarctation is not treated, it often results in various complications. Some are caused by the enduring high blood pressure triggered by the defect while others occur after treatment. Common complications include high blood pressure, aortic stenosis, aneurysm, stroke, aortic tear or rupture, coronary artery disease, heart failure, and hemorrhage in the brain. Also, if the condition is severe, the heart may be unable to pump sufficient blood to other body organs. Such a situation can damage the heart and also lead to kidney failure.

In most cases, it is not possible to prevent congenital heart defects like truncus arteriosus. Perhaps the only prevention strategy involves mitigating the risk factors associated with pregnancy. If someone is planning to have a baby, it is advisable to get vaccinated against rubella and other viruses. Also, women should avoid certain medications during pregnancy, and talk to a physician about the risks linked to diabetes. Aortic coarctation cannot be prevented since it occurs at birth. However, if the infant has a condition that increases the chances of the defect occurring, then early detection is recommended.

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