Transposition of the great arteries in children
Introduction
Introduction to pediatric aortic transposition Transposition of thegreatarteries refers to the connection of the right atrium to the right ventricle, the right ventricle emitting the aorta, and the left ventricle connected to the left atrium and emitting the pulmonary trunk. Large blood vessel dislocation, also known as large blood vessel translocation, is an anatomically interchangeable position between the aorta and the pulmonary artery, forming a congenital malformation of systemic circulation and abnormal pulmonary circulation. Normally, the left ventricle is connected to the aorta and the right atrium is connected to the pulmonary artery. The patient is not treated with a poor prognosis. The infant died 30% in the first week after birth, 50% died within 1 month, and 70% died within 6 months. basic knowledge The proportion of illness: 0.03% Susceptible people: infants and young children Mode of infection: non-infectious Complications: pulmonary hypertension heart failure
Cause
Pediatric artery transposition cause
(1) Causes of the disease
The occurrence of large vessel dislocation is closely related to the cardiovascular torsion during fetal life and the developmental separation of arterial cone. The occurrence and anatomical classification of this disease are quite complicated. The pericardial tube is twisted. Normally, the right ventricle is D-Loop. The right ventricle is on the right side, the left ventricle is on the left side, the aortic cone is located on the right posterior side, and the pulmonary artery cone is on the left front. The heart tube is developing. In the process, such as left-to-left sway (L-Loop), or the arterial cone from the ventricle origin is not spiraled and developed in a straight line, the right ventricle is left, the left ventricle is on the right, or the aorta is on the right. The position of the pulmonary artery in the right posterior changes. Van Praagh divides the large vessel dislocation into 8 types, of which type II, III, VI, and VII are physiologically corrected, and the other 4 types are physiologically uncorrectable. Caused by right iliac crest dislocation (type I, VIII), left iliac crest caused by dislocation of the left iliac crest (III, V type), but the right iliac crest can also occasionally cause dislocation of the left iliac crest ( Type II, VII), the right turn can also be caused by the left turn Large blood vessel dislocation (IV, VI type), therefore, generally I, III, V, VII type is more, II, IV, VI, VIII type is rare, in the above type 8 as the body, there is no horizontal shunt between the lung circulation The child can not survive, almost all patients have intracardiac traffic, 2 / 3 cases have open arterial catheters, about 1/3 of cases with ventricular septal defect, the offspring of the diabetic mother often suffer from complete large blood vessel dislocation, in addition, It is still possible to have pulmonary stenosis, tricuspid atresia, endocardial pad defect, right heart, visceral transposition with left heart, and single ventricle, single atrium, aortic coarctation and other deformities.
(two) pathogenesis
The most common type of complete transposition of the great arteries is the right type of transposition, that is, the ascending aorta starts from the right ventricle and is located in the right front; the pulmonary artery starts from the left ventricle and is located at the left rear, thus forming two distinct circulatory systems, which circulate After the: "right room right ventricle aorta whole body body vein right atrium"; and "left atrium left ventricle pulmonary artery lung pulmonary vein left atrium", the child must be accompanied by two large after birth The shunting traffic between the cycles can sustain life. The traffic can be in the atria, ventricle or aorta, that is, through the patent foramen ovale, atrial septal defect, ventricular septal defect, arterial catheter, occasional bronchial artery, through these channels. Part of the oxygenated blood can enter the systemic circulation from the pulmonary circulation, and the hypoxic blood flows from the systemic circulation into the lungs. As a result, the systemic blood consists of two parts: the main part is the venous blood returning to the aorta, and the small part is the flow through the traffic. The blood with high oxygen content, this shunt supplies the oxygen required by the systemic circulation, so it is effective pulmonary circulation; the same pulmonary blood flow is also composed of two parts; most of them are pulmonary vein blood, and a small part is the body circulation. The flow of the venous blood, the latter can enter the lungs for oxygen exchange, so it is an effective systemic circulation. It can be seen that the greater the effective blood flow, the higher the oxygen saturation of the systemic arteries, the lighter the sick child can be lighter, but too much The shunt increases the burden on the heart and lung circulation, leading to severe heart failure and early pulmonary hypertension. When the patient is accompanied by pulmonary stenosis, the pulmonary circulation blood flow is appropriately limited, the burden on the heart is reduced, and pulmonary hypertension is prevented, so only those Children with larger bodies, pulmonary circulation, and appropriate pulmonary stenosis can live longer.
According to hemodynamic changes, the disease can be divided into 4 types: type I: complete ventricular septum; type II: complete ventricular septal with pulmonary stenosis; type III; with large ventricular septal or single ventricle or large patent ductus arteriosus; type IV : With ventricular septal defect and pulmonary stenosis, type I is the most common, type IV prognosis is better.
Prevention
Prevention of pediatric aortic transposition
Ask family history to understand the genetic situation, investigate the impact of environmental factors to explore the cause of congenital heart disease, Shaw through the investigation of the address to understand the environmental teratogenic factors that the pregnant mother may be exposed, the address of the mother's production is sometimes used to represent The address of the early pregnancy was estimated by environmental factors. The authors investigated the address of the mother at the time of pregnancy and birth. About 24.8% of the mothers moved between the beginning of pregnancy and production, so observing the production address may reduce congenital malformation and the mother's exposure to the environment. The positive result of the association should be investigated in the environment of the address at the time of pregnancy. Schwanitz advocated that the detection of cardiac malformation before birth can be used as an indication for chromosomal examination. The authors mentioned that 588 fetuses were diagnosed with growth retardation and/or congenital malformation before birth. A chromosome examination was performed, and 116 (19.7%) of these cases were confirmed to have chromosomal abnormalities. Among these malformed fetuses diagnosed before birth, 102 (17.3%) of the fetuses with cardiac malformations, therefore, cardiac malformations For the most common malformations, 41 fetuses (40.2%) have chromosomes in the fetus that was diagnosed with a cardiac malformation before birth. Chang (trisomy 21 to 18 and is most common) syndrome.
In addition to monitoring the fetus, the mother's disease should also be monitored. Breton reported that the mother had phenylketonuria, and the plasma of phenylalanine continued to increase during pregnancy, and the child born had a cardiac malformation, Breton reported. A child's coronary artery abnormality originates from the right pulmonary artery, ventricular septal defect, fetal growth retardation and facial deformity. The phenylalanine in the mother's plasma continues to increase during pregnancy. The cardiac malformation is diagnosed 8 months after birth, and its developmental delay It is caused by maternal phenylketonuria, which can also cause ventricular septal defect and coronary artery malformation. The authors suggest that if the mother begins a dietary treatment before pregnancy, it may prevent fetal damage, so if there is a cause In-depth understanding, before pregnancy, pregnancy can be used to monitor maternal disease and fetal malformation of pregnant mothers and fetuses. If possible, try to prevent fetal congenital malformation, but from genetics and environment From the point of view of harm, the cause of congenital heart disease is not fully understood, and most of them are powerless in prevention. Explaining the cause and fundamentally preventing the occurrence of congenital heart disease is still an extremely difficult task, and it is still necessary for scholars in clinical and basic fields to work together to explore.
Complication
Complications of transposition of children with large arteries Complications pulmonary hypertension heart failure
Pulmonary hypertension, heart failure, embolism, etc.
Symptom
Pediatric aorta transposition symptoms Common symptoms Heart murmur cyanosis systolic murmur ventricular hypertrophy edema neonatal cyanosis ventricular septal defect congestive water pulse heart failure
In neonates with a large ventricular septal transposition, there is less exchange of blood flow between the two major cycles, and there is obvious cyanosis (completely septal ventricular septum and poorly mixed blood cyanosis), which can be within hours of birth. That is, it is found, and in most cases, the only symptom, physical examination shows obvious cyanosis, peripheral vascular pulse is normal, right ventricular beat is enhanced, auscultation is 1st, 2nd heart sounds bright, 2nd heart sound is often single or mildly split, heart murmur is soft Or absent, soft jet murmurs may be caused by functional left ventricular outflow tract murmur or patent ductus arteriosus, when there is a large inter-cycle shunt, such as large patent ductus arteriosus or large ventricular septal defect, due to exchange If the blood flow is high, the symptoms are mainly congestive heart failure, accompanied by mild cyanosis, and the children with large patent ductus arteriosus usually have symptoms within 1 week after birth. The typical performance is water flushing. Pulse, continuous murmur may not be obvious; infants with large ventricular septal defect usually have symptoms of heart failure 2 to 4 weeks after birth, early pulmonary vascular resistance is still high, murmur Not obvious, but in the first few weeks after birth, the development of pulmonary hypertension occurs in the lower left sternal border, and the third heart sound gradually appears. The galloping of the heart and the second sound of the pulmonary artery caused by heart failure can be heard at the apex of the pulmonary vein. The middle diastolic murmur caused by increased blood flow, cyanosis is obvious when the left ventricular outflow obstruction leads to pulmonary stenosis, and the systolic murmur is louder on the upper left edge of the sternum, except for the aortic valve close to the front chest wall to make the second heart sound In addition, other clinical manifestations are similar to the tetralogy of Fallot. In patients with ventricular septal defect with poor anterior misalignment, it is necessary to pay attention to the presence of left ventricular outflow tract obstruction. If the femoral artery beats weakly, the arm artery Normal or enhanced pulsation may be accompanied by interruption or edema of the aortic arch. In addition, there may be a differential cyanosis in the upper body than in the lower body.
1. Clinical features
Complete large vascular dislocations are more common in men. The ratio of male to female is 2:1 to 3:1. The most prominent clinical manifestation is that there is a cyanosis at birth. The degree of cyanosis increases with the increase of body weight, such as without interventricular septum. Defects, the cyanosis is more obvious, while the breathing is faster, the liver is large, progressive heart failure, such as with patent ductus arteriosus, the blood flow often from the pulmonary artery to the aorta, then the lower body and lower extremity cyanosis is higher than the upper body and upper limbs Light, the child often died early, physical examination can hear systolic murmur, the third edge of the sternum, the murmur between the four intercostals suggests a combined ventricular septal defect; the systolic murmur of the bottom of the heart is prompted with pulmonary stenosis, more than half of the cases 2 heart sound split.
2. Imaging examination
(1) X-ray chest examination: showing pulmonary congestion, large blood vessel shadow changes and left and right ventricular enlargement, because the ascending aorta is emitted in front of the pulmonary artery, the posterior anterior chest radiograph is in the main, the pulmonary artery shadows overlap, and the typical large The blood vessel shadow is narrow, the heart shadow increases to the sides, is egg-shaped, and increases day by day.
(2) Electrocardiogram examination: visible right axis deviation, right atrial right ventricular hypertrophy and other changes, such as combined with large ventricular septal defect can also see biventricular hypertrophy.
(3) Ultrasound examination: two echoes of aortic valve and pulmonary valve can be seen at the same detection site, or the aorta is in the left front, the pulmonary artery is in the posterior, and the combined intracardiac malformation.
(4) Magnetic resonance tomography: the transverse surface shows the aorta in the right front, the sagittal plane shows the aorta in front, and the right atrium is emitted, and the pulmonary artery is in the posterior, from the left heart chamber.
(5) Cardiac catheterization: the pulmonary artery oxygen saturation is significantly higher than the aorta; the right ventricular pressure is equal to the systemic circulation, or the catheter enters the left ventricle through the large ventricular septal defect, etc., if there is no ventricular septal defect, the blood oxygen level in the atrial level The saturation increases.
(6) Cardiovascular angiography: It is of great value for the diagnosis of this disease. The position of the semilunar valve, the location of the defect, the size and direction of the flow, etc. should be noted in the angiography.
Examine
Pediatric transposition of the great arteries
Peripheral blood can be found to have increased red blood cells and increased hemoglobin.
Chest X-ray
At birth, the heart size and lung field are normal, but the mediastinal shadow is narrow, which may be related to the anterior and posterior position of the main and pulmonary arteries and thymic hypoplasia caused by hypoxia and stress. With the increase of pulmonary blood flow and congestive heart failure Further development, the heart enlarges, the pulmonary vascular shadow gradually becomes obvious, and then forms an "egg-shaped" heart shadow. When accompanied by a large ventricular septal defect, the heart shadow is larger, the lung field is more congested, and the opposite is accompanied by left ventricular outflow. When the obstruction is obstructed, the lungs are in ischemia and the heart is normal.
2. ECG
There is no specific change in the electrocardiogram in the first few days after birth. The frontal QRS axis is between 90° and 120°, the right chest lead is R wave, the right ventricle is dominant, and the ventricular septum is intact. Within a few weeks. Continuous right axis and right ventricular hypertrophy may occur, with large ventricular septal defect, manifested as double-chamber hypertrophy, even if there is obvious left ventricular outflow obstruction or increased pulmonary vascular resistance, simple left ventricular hypertrophy is rare.
3. Echocardiography
At present, echocardiography has become an important imaging method for the diagnosis of transposition of the great arteries. In addition to making a diagnosis, the purpose of echocardiography is to include a shunt assessment between the pulmonary and pulmonary circuits, showing associated malformations and clarifying the anatomy of the coronary arteries. Morphology and decide which surgical plan to take, and more and more balloon ostomy is successfully implemented under the guidance of echocardiography alone. Under the xiphoid process, two aorta can be displayed simultaneously by changing the direction of the probe. They are sent from the left and right ventricles, parallel upwards, and the posterior position of the arterial trunk from the left ventricle, which branches out of the pulmonary artery, suggesting that the pulmonary trunk is dry. The long and short axis of the parasternal can also show the parallel relationship between the two large arteries. The short axis shows both The relative positional relationship is more clear, and it is usually seen that the aorta is located in the right front of the pulmonary trunk.
The lower section of the xiphoid can fully observe the intersection of the ventricle, and the sternal or high sternal long axis can clearly show the patent ductus arteriosus, such as concurrent ventricular septal defect, left ventricular outflow obstruction, outflow tract septum alignment Two-dimensional echocardiography such as poor and aortic arch deformity can show that Doppler ultrasound can show the severity of outflow obstruction. In addition, echocardiography can accurately evaluate the origin of three major coronary arteries and the orientation of the epicardial surface: The parasternal short-axis view can clearly show the opening position of the coronary artery in the aortic sinus. However, it is necessary to pass multiple cuts to comprehensively evaluate the coronary artery. Secondly, ultrasound can also detect some important coronary abnormalities, such as A single coronary artery, the coronary part of the aortic wall, the ventricular septum with a large artery transposition in the infant, before the arterial switch procedure, often requires multiple ultrasound examinations to understand the lumen size, room Wall thickness, left ventricular volume and morphology, ventricular septal curvature may indicate left ventricular systolic pressure, and aortic transition surgery requires left ventricle Debut size and pulmonary valve function was normal, but dynamic left ventricular outflow tract obstruction is not a contraindication to surgery aorta conversion.
4. Cardiac catheterization
Because echocardiography can obtain detailed anatomical information, cardiac catheterization has rarely been used for simple diagnosis. In most cardiovascular treatment centers, cardiac catheterization is only used for balloon ostomy, however, the ball The capsular septum can still be successfully performed under the guidance of echocardiography, and in the hospital where the aortic transection is performed earlier, if the child has a large foramen ovale and patent ductus arteriosus, the pulmonary circulation When adequately mixed, no need for cardiac catheterization, detailed evaluation of hemodynamics by cardiac catheterization is limited to complex aortic transposition with severe left ventricular outflow obstruction, multiple hole ventricular septal defect, aortic arch deformity and pulmonary artery in the later stage In children with diseases, the application of cardiovascular angiography is also rare. When there is suspected edema, the right ventricle or ascending aorta lateral or long-axis angiography can show the location of edema, and the left ventricular long-axis angiography can show Left ventricular outflow tract obstruction, in addition, coronary angiography or transvenous venous root balloon occlusion reverse angiography can show the anatomy of the coronary artery, posterior anterior The open angle of the head can clearly see the opening of the coronary artery and its distribution and direction. However, echocardiography can reliably display the coronary anatomy of almost all children. Therefore, most operations do not require angiography before surgery. .
5.CT and MRI
CT and MRI examinations are helpful in the diagnosis of complete transposition of the great arteries. For complex types of congenital heart disease involving atrioventricular connections and ventricular aortic connections, the position of the atria, ventricular position, aortic position and their interconnection are judged. It is very important that CT and MRI examinations can not only determine the atrial position by directly displaying the auricle, but also infer the atrial position by minimizing the projection of the bilateral main bronchus. The MRI spin echo T1W image can show the small myocardial small. The roughness of the beam, according to which the position of the ventricle is judged, the trabecular myocardium is the morphological right ventricle, the smooth is the morphological left ventricle, the atrioventricular connections are consistent, and the inconsistent connection of the ventricular aorta is the diagnostic point of complete transposition of the great arteries, and then Also need to observe the size of the left and right ventricles, the presence and size of the ventricular septal defect, the location, the presence or absence of pulmonary stenosis.
6. Cardioangiography
The key to complete angiography of the great arterial transposition is to deliver the cardiac catheter into the left ventricle. The right cardiac catheter can pass through the foramen ovale to the left atrium to the left ventricle. The catheter is selected from the NIH right heart contrast catheter or balloon floating contrast catheter. Omega Parker 350, 1.5ml / d, as fast as possible injection, the position of the projection in the left ventricular angiography preferred long-axis oblique position, long-axis oblique projection X-ray and ventricular septal tangency, can clearly show the pulmonary artery In the left ventricle, the relative pressure levels of the two ventricles can be preliminarily determined according to the deviation direction of the interventricular septum. The long-axis oblique left ventricular angiography can also better display the location, size and number of the ventricular septal defect, and the left ventricular outflow tract. Stenosis and stenosis of the pulmonary valve, sometimes plus left ventricular angiography to exclude peripheral pulmonary stenosis, lateral right ventricular angiography can show that the upper artery starts from the right ventricle, has a cone under the valve, and can show the presence or absence of an arterial catheter If the aorta is narrowed and the aorta is narrowed, the right ventricle can be used with a right heart angiography catheter such as NIH. For example, a retrograde cannulation of the aorta to the right ventricle is better with a pig tail left angiography catheter. Omi Parker 350, 1.5ml / kg, as fast as possible injection, lateral right ventricular angiography on the relative position of the aorta and the displacement of the cone can be well displayed, the conical interval forward, easy to accompany aortic coarctation For those who are preparing for transposition of the aortic transposition, it is necessary to perform ascending aorta angiography to observe the coronary artery type. The catheter can be selected from the balloon to float the right heart angiography catheter to advance the ascending aorta through the vein, and the balloon is partially inflated. After the ascending aorta, the ascending aorta angiography can better display the coronary artery. The catheter can also be retrogradely delivered to the ascending aorta via the femoral artery cannula. The position of the projection is positive or positive to the angle of the foot. Completeness The most common type of transposition of the great arteries is the left coronary artery from the left posterior sinus, the right coronary artery from the right posterior sinus, and the second common type is the left anterior descending artery from the left posterior sinus, right coronary The artery originates from the right posterior sinus and the left circumflex artery originates from the right coronary artery.
Diagnosis
Diagnosis and differential diagnosis of pediatric aortic transposition
diagnosis
Diagnosis can be performed based on clinical performance and laboratory tests.
Differential diagnosis
Common arterial trunk
Similar to the complete aortic dislocation, the patient has a hairpin, and a strong aortic second heart sound can be heard between the 2nd and 3rd ribs on the left sternal border. The difference is that the heart murmur of the common arterial trunk is often continuous. The X-ray plain film shows the mediastinum width, the heart is enlarged, and the electrocardiogram shows double-chamber hypertrophy, and the cardiac catheterization can confirm that there is only a single arterial trunk, that is, the common arterial trunk.
2. Complete pulmonary venous malformation drainage
When the total trunk of the pulmonary veins is obstructed, the symptoms of patients with complete pulmonary venous malformation are aggravated, and the cyanosis is also obvious. At this time, the complete aortic dislocation may be suspected, but the X-ray film of the former shows a typical "8" sign; the left sternum The marginal systolic murmur is lighter, the position is higher, and the second heart sound is often divided, and the cardiac catheterization and echocardiography can clearly identify the two diseases.
3. Fallot tetralogy
Similar to the complete aortic dislocation, the patients have cyanosis; the patients with aortic dislocation with ventricular septal defect have similar heart murmurs, but the children with tetralogy of Fallot often develop late cyanosis, usually magpie, X The flat film has the characteristics of a shoe-shaped heart, with less pulmonary blood and a narrow mediastinum. Echocardiography can be used for further differential diagnosis, and cardiac catheterization and right ventricular angiography are more helpful for differential diagnosis.
