Persistent ductus arteriosus is the term used to describe the postnatal open connection between the aorta and the pulmonary artery. Prompt diagnosis and appropriate therapy prevents complications such as, in the worst case, death of the newborn. If successful and complete occlusion occurs, no further complications are to be expected.
What is persistent ductus arteriosus?
Persistent ductus arteriosus refers to a heart defect in the newborn child. Prenatally, there is a connection between the aorta and pulmonary artery, bypassing the pulmonary circulation of the unborn child (right-to-left shunt). Normally, a postnatal increase in oxygen in the blood causes contraction and subsequent regression of the connection. This should occur within the first three days after birth. In about 30 percent of all infants born before 31 weeks’ gestation, this is not the case. If the ductus remains open, shunt reversal (left-to-right shunt) occurs. Persistent ductus arteriosus exists when the connection remains open for more than three months after birth. Persistent ductus arteriosus accounts for five to ten percent of all congenital heart defects and often occurs in combination with other heart defects. Female newborns are two to three times more likely to be affected than males.
Causes
The cause of persistent ductus arteriosus is unclear. However, it is shown to occur more frequently in premature infants, especially those with low birth weight, and also in perinatal oxygen deprivation and births at high altitude. Asphyxia, which is an impending asphyxia caused by a drop in oxygen levels while carbon dioxide is retained, can also cause the duct to remain open. Some infants do not spontaneously adjust their breathing to the changed circumstances after birth, which is called respiratory adaptation disorder. Another cause may be chromosomal aberrations such as trisomy 21 or trisomy 18. In the course of rubella embryopathy, in which the rubella virus is transmitted from mother to fetus, the ductus may also remain open. Familial clustering is usually not the case.
Symptoms, complaints, and signs
Symptoms depend on the size of the shunt. A small passage usually remains free of symptoms. With a larger passage, a typical heart murmur is audible on auscultation, which is most prominent in the left upper thorax. In addition, there is exertional dyspnea, tachycardia, respiratory distress, cyanosis, fatigue, and poor growth, as well as apnea and bradycardia in premature infants. In extreme cases, recurrent respiratory infections, congestive heart failure, or in the elderly, ductal calcifications and aneurysms may occur. Another complication is inflammation of the inner lining of the heart or arteries, which can lead to septic emboli and lung abscesses. An asymptomatic course has a good prognosis but carries a lifelong risk of endocarditis. A large duct may involve pulmonary hypertension as well as irreversible alteration of the pulmonary vasculature.
Diagnosis and disease progression
Diagnostically, there are several possibilities. Prenatal diagnosis is not possible because the ductus is open in all unborn children. If persistent ductus arteriosus is suspected, several procedures are used. On pulse measurement, pulsus celer et altus may be suggestive as a sign of a large blood pressure amplitude. The typical permanent heart murmurs are clearly heard on auscultation. Depending on the pressure and volume load, signs of hypertrophy of the heart are visible in the ECG. Enlargement of the left heart is also seen on chest x-ray in the presence of a large shunt. Echocardiogram and cardiac catheterization examination may demonstrate the ductus and accompanying abnormalities. Differential diagnoses include arterio-venous fistulae, ventricular septal defect, and peripheral pulmonary stenosis.
Complications
The ductus arteriosus is important prenatally to connect the pulmonary circulation to the systemic circulation because pulmonary breathing is not yet possible. Only after birth does the ductus arteriosus close independently, creating a separate pulmonary circulation from the systemic circulation.Complications that may occur due to an untreated persistent ductus arteriosus depend on the size of the ductus and the stage of development of the newborn. Smaller connections between the two blood circuits may be completely asymptomatic and do not require immediate treatment. In larger connections between the two blood circuits, blood flows from the aorta into the pulmonary artery, increasing pulmonary blood pressure. As typical sequelae, this can result in irreversible sclerotization of the pulmonary vessels, making pulmonary hypertension irreversible; it becomes virtually fixed. Further sequelae are dilatation of the left atrium and the left ventricle due to the higher degree of filling of the left heart. In the long term, the changes in the heart lead to heart failure. It is therefore advisable to separate the two blood circuits in newborns with a relatively large persistent ductus arteriosus by means of a small operation. Usually, such procedures can even be performed in a cardiac catheterization laboratory, eliminating the need for surgical management.
When should you see a doctor?
In any case, this condition requires a medical examination and further treatment. If no treatment occurs, this disease usually leads to premature death of the affected person or other life-threatening complications. A doctor should usually be consulted if the affected person suffers from relatively loud and clearly audible heart murmurs. This may also include pain in the heart, and this pain may be accompanied by severe difficulty breathing or a blue discoloration of the skin. Severe fatigue or slowed development in children may also indicate this disease and should always be examined by a physician. Furthermore, the disease leads to heart failure, so that the patient’s performance also decreases and he appears tired or sluggish. The disease can be diagnosed by a general practitioner. However, further treatment is carried out by a specialist. Whether this will result in a reduced life expectancy cannot generally be predicted. The earlier treatment is given, the higher the likelihood of a positive disease outcome.
Treatment and therapy
Early diagnosis and therapy are essential, especially in preterm and low-birth-weight neonates, in whom both comorbidity and mortality are much higher because of hemodynamic instability. Persistent ductus arteriosus should always be closed to minimize the risk of endocarditis. Therapy of persistent ductus arteriosus is done in different ways. Medication can be given with prostaglandin synthesis inhibitors. Under no circumstances should these be administered during pregnancy, as it is imperative that the ductus remain open prenatally. In the case of premature birth, drug therapy is usually always used. There are special preparations for this purpose, which can be used in births before the 34th week of pregnancy. A minimally invasive treatment method is the insertion of an IUD or a screen via cardiac catheters, which also close the ductus. In contrast to drug therapy, this method is more commonly used in older children. Operatively, ligation of the duct is possible. The lethality rate for this procedure is one percent in children and twelve percent in adults. Spontaneous closure of the duct is possible. If closure is successful, the neonate has the same prognosis as the normal population. Further endocarditis prophylaxis is useful for six months to check the outcome of the treatment. After that, follow-up examinations are no longer necessary.
Outlook and prognosis
The best prognosis is for persistent ductus arteriosus if the duct can be closed. The problem is that this disorder should not occur at all in a newborn. Normally, this connection closes on its own after birth. However, in premature infants, there is more often a failure of this mechanism. In rare cases, minimally invasive ductal surgery becomes necessary. Having to operate on premature infants or newborns because of a persistent ductus arteriosus carries high risks.For this reason, pediatric cardiologists strive to close the ductus arteriosus botalli, which has not closed on its own, by means of a suitable drug, especially in premature infants. This drug inhibits the formation of prostaglandin. Prostaglandin is a messenger substance that influences the immune system. When prostaglandin levels fall, the persistent ductus arteriosus often closes after all. However, the administration of “indomethacin” is not possible or successful in every case. If this method fails or proves inapplicable, the unclosed connection between the aorta and the pulmonary artery in the affected infant can only be closed surgically. However, this is only done in older children by means of a cardiac catheter. If the ductus is successfully sealed, the prospects for a long life are quite good. The prognosis is significantly worse for a persistent ductus arteriosus if it occurs together with other heart defects.
Prevention
Prophylaxis of persistent ductus arteriosus is not possible during pregnancy because the open duct is essential for the development of the newborn. Several studies investigated the efficacy of individual drugs, finding no significant difference. Another study investigated the relationship between phototherapy in premature infants, which is also used for jaundice, and keeping the ductus arteriosus open. However, no clear efficacy was found. Because efficient prophylaxis is very difficult or impossible, timely diagnosis and intervention are all the more important for the health of the newborn.
Follow-up
Follow-up care is especially necessary after surgical closure of persistent ductus arteriosus. Surgery is followed by transfer of the patient to the intensive care unit for observation. If a cardiac catheter has been placed on a leg, it is important not to move it independently at the beginning. Heavy physical exertion should be avoided during the first week after the intervention. To prevent infestation with harmful bacteria, appropriate medication is administered intravenously. The patient also receives heparin. As part of follow-up care, the patient must take clopidogrel for three months and acetylsalicylic acid (ASA) for six months. The administration of these drugs serves to counteract the formation of blood clots on the materials used. Antibiotic agents administered protect the heart and vessels from inflammation. One day after the procedure, X-rays are taken for control. After about six months, an examination by swallow echo takes place. If any abnormalities are detected during the follow-up, they must be clarified by a physician as soon as possible. To ensure the success of the treatment, regular follow-up examinations should take place. Only a few years later, provided that no symptoms appear, can these examinations be dispensed with completely. Whether this is also possible in children who have undergone cardiac catheterization cannot be stated unequivocally due to a lack of long-term experience.
Here’s what you can do yourself
Persistent ductus arteriosus in newborns can be treated with accurate dosing of medications or surgery. Parents of the affected child should follow the doctors’ instructions carefully in everyday life. Infections and other diseases should be avoided if possible, especially in the first period after birth. In case of the diagnosed ductus arteriosus or in case of a suspicion of this heart defect, it is very important to pay attention to the heart murmurs of the newborn. Together with fever or other symptoms, such observations indicate the medical problems. Blood pressure also plays a role. For parents, regular follow-up checks are essential. This is the only way to check whether the child is healthy and can grow up normally. The appointments for the examinations must be strictly adhered to. If an operation is performed, further doctor’s appointments also follow. At the same time, parents can carefully observe their child. In this way, they can detect any problems in time, such as secondary injuries, inflammations or a curvature of the back. In such cases, they should not wait for the next examination appointment, but should see a doctor as soon as possible. It is also important that the newborn is not subjected to too much strain.
