Truncus arteriosis communis is a very rare heart defect in newborns that is caused by incomplete separation of the arterial trunk of the lungs from the arterial trunk of the systemic circulation. The aorta and the pulmonary artery originate in a common trunk, so that the oxygen-poor arterial blood of the pulmonary circulation mixes with the oxygen-rich arterial blood of the systemic circulation. TAC is almost always associated with a septal defect just below the common arterial trunk and requires prompt postnatal surgical management.
What is truncus arteriosis communis?
The main feature of the very rare heart defect known as truncus arteriosus communis ( TAC ) is the common origin of the body artery ( aorta ) and the pulmonary artery ( arteria pulmonalis ) from both heart chambers. At the same time, there is always a defect in the septum between the left and right ventricle ( ventricular septal defect, VSD), which is located directly below the confluence of the TAC. For introduction to hemophagocytic lymphohistiocytosis, please visit sciencedict.com.
In fact, the deoxygenated arterial blood of the pulmonary circulation mixes with the deoxygenated arterial blood of the systemic circulation. Depending on the origin of the pulmonary artery from the common trunk with the aorta, a distinction is made between types I to IV of a TAC.
What all four categories have in common is that there is only one common heart valve, the aortic valve that has been converted into a truncus valve. However, it usually has stenoses or its size is not adapted to the conditions, so that there is limited functionality from the outset.
During the embryonic and fetal stages up to birth, the pulmonary circulation, or lesser systemic circulation, is short-circuited via the confluence of the ductus arteriosus with the aorta, the main artery of the body. During and after birth, the ductus arteriosus closes, separating the two bloodstreams. Oxygen and nutrients are supplied prenatally via the mother’s bloodstream.
The preparation for the possible later separation of the large circulation from the pulmonary circulation already takes place between the 32nd and 36th day of pregnancy. The originally single and common arterial trunk in the even earlier development phase, the truncus arteriosus, is divided into the aorta and truncus pulmonalis. The septum forms between the two arterial trunks, the dividing wall between the right and left ventricle.
In rare cases, the two arterial trunks do not separate and the septum also does not reach to the mouth of the two arterial trunks, so that the separation between the two blood circulation systems cannot take place postnatally – even after the ductus arteriosus has been properly closed.
About 40 percent of newborns affected by TAC show a gene defect on the long arm of chromosome 22 at locus 22q11.2 that is causally related to TAC. For the rest of those affected, the reasons that lead to the malformation in the heart have not yet been sufficiently clarified.
Symptoms, Ailments & Signs
Symptoms and complaints that are triggered by a TAC only appear postnatally, because the two blood circulation systems are also short-circuited prenatally in the healthy fetus. In some cases, the malformation of the heart is already noticeable in prenatal ultrasound examinations, so that further targeted examinations provide clarity about the extent and category of the TAC.
In the other affected newborns, a number of non-specific symptoms appear soon after birth, which are similar to those of oxygen deficiency with a different cause. The newborns show an increasing tendency to turn blue ( cyanosis ) and pulmonary hypertension is usually observed.
The newborns usually suffer from poor feeding and their respiratory rate is significantly increased. If left untreated, heart failure will soon set in. Rapid development of hepatomegaly, an enlarged liver, can also occur. The entire development of the newborn is disturbed.
Diagnosis & course of disease
If the diagnosis has not already been made prenatally, routine auscultation of the heart murmurs provides the first indication of the presence of an abnormality in the heart system. A targeted echocardiography can clarify whether, for example, there is a septal defect and whether there is only a single common arterial outlet from the heart – usually directly above the septal defect.
In addition to magnetic resonance imaging (MRI), further diagnostic measures include angiocardiography, an X-ray examination of vessels close to the heart and the heart itself as part of a cardiac catheter examination. The ECG also provides indications of certain abnormalities. The course of the TAC is serious.
As a rule, the symptoms of truncus arteriosus communis appear immediately after the birth of the children. First and foremost, there is a severe undersupply of oxygen, so that the children die without treatment. The skin turns blue and the brain and internal organs are damaged.
Children need prompt treatment. The children also suffer from a severe lack of drinking, which leads to dehydration and severe deficiency symptoms. Furthermore, untreated truncus arteriosus communis leads to renal insufficiency. The liver is also significantly enlarged in the disease and can lead to pain.
The child’s development is significantly restricted by the disease. Heart failure can also occur. Parents and relatives also often suffer from psychological problems or severe depression with Truncus arteriosus communis.
The treatment of truncus arteriosus communis is carried out by various surgical interventions. Complications cannot be predicted universally. However, the life expectancy of the children is significantly reduced by the disease.
When should you go to the doctor?
In the case of truncus arteriosus communis, the patient is dependent on medical examination and treatment. This is the only way to prevent further complications or a further worsening of the symptoms. If the disease is not treated, it can lead to death in the worst case. Therefore, in the case of truncus arteriosus communis, an early diagnosis with subsequent treatment must be carried out in any case. A doctor should be consulted for this disease when the ultrasound examination shows that the arteries to the fetus are closed.
This is usually recognized directly by the gynecologist or in a hospital. In many cases, the child also has a drinking problem or suffers from severe heart problems. If these symptoms occur, a doctor must be contacted in any case. A delayed development of the child can also indicate truncus arteriosus communis and should also be checked by a doctor. With this disease, a general practitioner or a pediatrician can be consulted. Further treatment is then carried out by a specialist. It is not generally possible to make a prediction about the further course.
Treatment & Therapy
The truncus arteriosis communis includes a serious malformation in the heart, which goes back to a malformation already during the embryonic stage. A drug treatment cannot bring lasting success, so that only a “mechanical” correction of the misalignment in an open heart operation remains as the means of choice.
The operation is performed as soon as possible in early infancy. Due to the individually different degrees of malformation, the corrective measures carried out during the operation on the “shut down” heart are also very individual. The main goal of surgery is to achieve an effective separation between the pulmonary and systemic circulation.
To do this, it is necessary to first repair the ventricular septal defect. The missing piece of septum or the hole within the septum is closed with a special plastic patch. In addition, the two pulmonary arteries are connected with a vascular prosthesis, which can come from animal material or from a human donor.
The other end of the vascular prosthesis is connected to the right ventricle. This ensures that the two circuits are separated from each other and the blood circuit is comparable to that of a healthy person.
Direct preventive measures to prevent a TAC are not known. Since the basis for the malformation already occurs during the embryonic stage between the 32nd and 36th day of pregnancy, it makes sense for women to consciously stay away from potentially toxic substances such as environmental toxins, alcohol and nicotine during the early phase of pregnancy in order to avoid the risk of the to minimize defects.
Because the mortality rate of infants suffering from truncus arteriosus communis is very high in the first six months, an operation must be performed, which in turn requires consistent aftercare. Follow-up checks should take place at regular intervals, because problems such as valve weakness and the risk of short circuits that do not grow with the surgery also exist after the surgical procedure. In some cases, additional surgical treatments are necessary.
The mortality rate after an operation of the truncus arteriosus communis is about ten percent. About 80 percent of babies who have surgery have a 10-year survival rate. Cardiological follow-up checks are among the indispensable follow-up measures. They must take place throughout life. During these examinations, the doctors pay particular attention to possible calcifications, narrowing (stenoses) and insufficiencies.
Pulmonary hypertension and ventricular arrhythmias are also of interest. Sometimes there is an increase in the truncus valve insufficiency that requires treatment. In addition, prophylaxis against endocarditis (inflammation of the inner lining of the heart) is necessary throughout life. In order to check the functions of the conduits (artificial tubes), echo checks and regular magnetic resonance imaging are carried out.
The truncus valve, the aorta (main artery) and the aortic arch are also checked. The conduits often have to be replaced after a few years. In more than 50 percent of all patients, the exchange takes place after five years.
You can do that yourself
The truncus arteriosus communis is a rare disease that primarily has to be treated surgically and with medication. Taking the prescribed medicines regularly is an important self-help measure that patients must strictly adhere to.
In addition, lifelong check-ups by the doctor are necessary. The parents and later the patient themselves must ensure that the appointments are kept. Comprehensive endocarditis prophylaxis is also necessary. In addition to taking antibiotics, you can prevent inflammation through a gentle lifestyle. Infections and cardiovascular diseases must be avoided at all costs. Otherwise, life-threatening endocarditis can occur. Should a feverish illness nevertheless occur, the doctor must be consulted. From now on, taking a strong antibiotic is necessary to cure the inflammation as quickly as possible.
Treatment usually takes place in a specialist clinic. The responsible cardiologist will suggest suitable self-help measures that can accompany the therapy of the truncus arteriosus communis. The supportive measures are based on the course of the disease and the chosen therapy. They should be discussed closely with the doctor so that incidents can be dealt with quickly.