Open arterial duct
The open arterial lumen (OAP) is widespread. Pathology is most commonly found in newborns. When isolated OAP, signs and symptoms are consistent with the flow of blood from left to right. The severity of the manifestation of the disease depends on the magnitude of the defect and pulmonary vascular resistance. If necessary, the closure of such anatomical education can be postponed until childhood or even maturity
The first successful bandage of the arterial duct was performed by Robert E. Gross at an eight-year-old girl at Boston Children's Hospital in 1938. [1 - en.hms.harvard.edu, Robert E. Gross, Harvard Medical School Office for Faculty Affairs.]
The open arterial canal may also be combined with other heart anomalies, which should be taken into account in the diagnosis. In many cases, the diagnosis and therapy of OAP are crucial for the survival of newborns with severe obstructive lesions in the right or left side of the heart.
Video Outdoor arterial duct. Congenital heart defects.
The arterial duct (AP) has a different name - botulla duct.The fetus is defined as a normal anatomical structure that connects the systemic and pulmonary part of the circulatory system. Normally, in newborns, AP is closed for 3 days after birth. However, 80% of preterm infants with a weight less than 750 g remain open more than 3 days after birth, and its constant permeability is associated with increased morbidity and mortality.
In an isolated form, an open arterial duct often develops asymptomatic.The OAP has been described in conjunction with virtually any other congenital heart disease, especially those that are characterized by cyanosis.The age of the patients when diagnosis can vary from infancy to old age.
The UCP classification for Kirichenko is based on angiography and includes five types:
- type A (conical);
- type B (window-like);
- type C (tubular);
- type D (complex);
- type E (elongated).
Depending on the degree of opening of the arterial duct (from 10% to 30%), four stages of OAP are distinguished:
- Stage 1 - Systolic pressure in the pulmonary artery is reduced and is 40% of the arterial.
- Stage 2 - moderate hypertension: systolic pressure in the pulmonary artery is elevated and is 40% -75% of the arterial.
- Stage 3 - pronounced hypertension: systolic pressure in the pulmonary artery is elevated and is 75% arterial.
- Stage 4 - Systolic pressure and resistance in the pulmonary artery are the same or more systemic, due to which blood discharges are carried out from the pulmonary artery to the aorta.
With large sizes of the open arterial duct there are pathological changes in the lung vessels (Eisenmenger symptom).
A bit of statistics:
- In children in the United States, the frequency of OAP is 0.02% to 0.006%.
- The incidence rate is increased in children who are born prematurely: 20% in preterm infants after 32 weeks of gestation, up to 60% in premature birth after 28 weeks.
- 30% of low birth weight babies
- Perinatal asphyxia usually only holds up the closure of the arterial duct, and over time, the channel usually closes without special therapy.
- As an isolated lesion, the open arterial duct is determined in 5-10% of all congenital heart defects.
No data confirm the racial susceptibility to OAP.Nevertheless, there is a predominance of women (the ratio between women and men is 2: 1), if the open arterial duct is not associated with other risk factors. In patients whose open arterial duct is associated with certain teratogenic effects such as congenital rubella, the incidence between men and women is the same.
An initial description of the arterial duct was carried out by Galen at the beginning of the first century. Harvey undertook further physiological studies in the field of embryonic circulation. However, only in 1888, Manro was able to open the bloodstream and reposition the arterial duct in a dead infant child.
50 years later, Robert E. Gross managed to lag open the arterial duct. [2 - Kaemmerer H; Meisner H; Hess J; Perloff JK Surgical treatment of the patent ductus arteriosus: a new historical perspective. Am J Cardiol. 2004; 94 (9): 1153-4] This was a remarkable event in the history of surgery, which marked the beginning of the field of surgery for congenital malformations on the heart.
Catheter closure of pathological education was first performed in 1971.
The first demonstration of the physiological closure of the arterial duct was carried out during multiple experiments in the 1940s, which was subsequently confirmed by exploratory studies.
Anatomy and pathophysiology
During fetal development, the fetal appendage is an important part of the circulatory system, which allows most of the blood leaving the right ventricle to bypass the lungs and pass into the descending aortic department. As a rule, only about 10% of the blood coming out of the right ventricle still passes through the pulmonary tissue.
Although the arterial duct is a normal structure in the development of the fetus, its presence is usually associated with other congenital anomalies of the cardiovascular system.
In the presence of complex congenital heart defects, the usual location of the duct may be broken. Anatomical anomalies can vary widely and are often common in combination with complex anomalies of the aorta. Structures that were mistaken for an open arterial duct during surgical procedures include aorta, pulmonary artery, and carotid artery.
The pathophysiology of closure of the AP is normal
As a rule, the functional closure of the arterial duct is carried out after about 15 hours of life in healthy infants born in due time. This occurs with a sharp contraction of the muscular wall of the arterial duct, which is associated with an increase in the partial pressure of oxygen (PO2), coinciding with the first breath of the newborn. There is a preferential blood flow shift; the blood leaves the duct and is directed from the right ventricle to the lungs. As long as the functional closure is not completed, some residual blood flow from left to right is carried out from the aorta through the duct and further into the pulmonary arteries.
There are several etiological factors in the development of open arterial duct:
- Chromosomal abnormalities
- Premature birth
Family cases of open arterial duct were registered, but the genetic cause was not determined. In infants born with an open arterial duct, the incidence of relapses among brothers and sisters is 5%. Some data indicate that up to one third of the cases are associated with a recessive symptom denoted by the PDA1 located on the chromosome 12.
Several chromosomal abnormalities are associated with constant passage of arterial duct. Implanted teratogenics include congenital rubella infection in the first trimester of pregnancy (in particular, 4 weeks after conception), as well as fetal alcohol syndrome, the use of amphetamine or the use of phenytoin by the mother.
Immature infants during pre-term birth contributes to the patency of the arterial duct.There are several predisposing factors, including the immaturity of smooth muscles within the structure or the inability of the immature lungs to clear blood from circulating prostaglandins, which accumulate in large numbers during pregnancy. These mechanisms are not fully understood. Conditions that contribute to low blood oxygen tension, such as immature lungs, concomitant congenital heart defects are also associated with the constant passage of the duct.
These include low birth weight, high prostaglandin concentration and hypoxia.
Common symptoms of an open arterial duct are as follows:
- tachycardia (increased heart rate);
- broken breath;
- shortness of breath (shortness of breath);
- Lack of growth [3 - MedlinePlus Patent Ductus Arteriosus Update Date: 21 December 2009];
- differential cyanosis, i.e., lowering of the lower extremities, except for the upper parts of the body.
Patients are most often in good condition, with normal breathing and heart rate. If the OAP is moderate or large, basically there is an extended pulse pressure and limiting peripheral impulses. Also visible ocular and carotid pulsations may be observed.
In addition to clinical signs, there are other diagnostic indicators indicating the presence of an open arterial duct.
Allows use of palpation, percussion, auscultation methods, which results in the following changes being determined:
- Palpation: apical push is shifted to the left and the bottom. A pulse with increased blood loss is defined as high and frequent.
- Percussion: the limits of the heart are extended to the left and up.
- Auscultatory: in the second to third intercostal, a continuous cardiac noise "machine" (usually from the aorta to the pulmonary artery, with a higher flow during the systole and a lower flow during diastole); The second tone over the pulmonary artery is intensified (second tone accent).
Additionally, instrumental diagnostic methods are performed, which help to determine the degree of hemodynamic impairment in the heart.
- Electrocardiography (ECG): there is a hypertrophy of the left or both ventricles. The early symptom of OAP is an increase in the amplitude of the tooth R and the appearance of the Q-tooth in 5-6 thoracic nodes.
- OGC radiography: cardiomegaly and enlargement of the left heart. Stagnant lung pattern is also defined. The arc of the pulmonary artery explodes, and the ascending part of the arch of the aorta is enlarged.
In some cases, angiography may be performed to detect changes in the cardiac blood flow.
Video Angiography is an open arterial duct
In many cases, the diagnosis and treatment of the open arterial duct are crucial for the survival of newborns with severe obstructive lesions on the right or left side of the heart.
Surgery is the basis for the treatment of OAP. Today, two types of surgical therapy are performed:
- A traditional surgical approach that entails thoracotomy (or, alternatively, thoracoscopy)
- Closure of the duct with a catheter.
Traditional surgical treatment is mostly performed successfully.Mortality from the surgical closure of the duct is less than 0.5%.Catheter effects are practically without serious consequences, although such patients are then under special observation.
In the future, further development of more complex catheter exposure methods is planned to facilitate the closure of the OAP. The future of pharmacological therapy in the closure of the OAP remains uncertain. The medical approach depends on a better understanding of the factors that speed up the closure of the duct.
Indications for surgical treatment of OAP:
- There is pronounced congestive heart failure.
- Drug therapy was ineffective and the patient was diagnosed with OAP symptoms.
Duct reconstruction may be postponed in cases where the patient has an asymptomatic course of the disease or his condition is well controlled using medication therapy. In such cases, surgical treatment can be performed at around age 4 when the risks of intubation are reduced, and the child is more able to understand the procedure and the treatment process. In some countries it is recommended to close the duct after 12 months or when the clinic appears.
Contraindications to surgical treatment of OAP
There is relatively little contraindication for the closure of the open aortic duct. The primary contraindication to the operation is a severe illness of the lung vessels.
Many associated cardiac anomalies, the so-called airborne lesions, depend on the OAP, in particular due to the maintenance of systemic blood flow. Premature closure of the AP without simultaneous reconstruction of other defects is contraindicated and may have fatal consequences. In particular, there can not be a separate closing of the OAP in the presence of the following vices:
- Hypoplasia of the pulmonary artery
- Pulmonary atresia
- Tricuspid anesthesia
- Transposition of large arteries
- Atorhasia of the aortic valve
- Atresia of the mitral valve with hypoplastic left ventricle
- Severe coarctation of the aorta
These patients should be made to try to maintain an open duct until a longer palliative shunt is created or a final reconstruction is completed.
If the arterial duct remains open, then heart failure may occur due to improper circulation in the lungs. There is also an increased risk of developing pulmonary hypertension or endocarditis. In addition, in the presence of a significant left-right blood discharge in newborns with low weight after delivery, there is a decrease in peripheral perfusion and delivery of oxygen, which causes tissue hypotrophy. Such a child may lag behind in development.
Prognostic conclusion with an open arterial duct, as a rule, is given to those patients whose problem is isolated. If the child was born before the term and it determines other consequences of prematurity, these complications, most often, worsen the OAP forecast.
After closing the open arterial duct, patients usually do not experience depressing symptoms and have no further cardiac complications. In preterm infants, who have had a large open artery, bronchopulmonary dysplasia develops more often.
Spontaneous closure of OAP in individuals over 3 months of age is rare.At the age of less than 3 months, spontaneous closure in preterm infants is 72-75%. In addition, in 28% of children with arteriosis ducts, which were conservative treatment (usually ibuprofen in prophylactic doses), the closure of defects is determined 94%..
In an adult patient, the prognosis more depends on the state of the pulmonary vasculature and myocardial condition, as well as the presence of congestive cardiomyopathy before closure of the duct. Patients with minimal or reactive pulmonary hypertension and limited myocardial changes may have a normal lifespan.
Some data suggest that the administration of indomethacin on the first day of life in all preterm infants reduces the risk of developing OAP and the complications associated with it. Indomethacin treatment in preterm infants may also reduce the need for surgical intervention [4 - Fowlie, PW; Davis PG; McGuire W (May 19, 2010). "Prophylactic intravenous indomethacin for preventing mortality and morbidity in preterm infants (Review)"].
Video to live is great! Open arterial duct