Congenital heart disease is a heart condition that exists in the mother’s body before the baby is born. It is caused by a problem in the formation of the heart during fetal life. The formation of the heart is an extremely complex process, and cardiovascular malformations can form if certain parts stop during growth, parts that should fuse do not fuse, parts that should rotate do not rotate or rotate out of place, parts that should absorb degeneration remain, internal connections are misaligned, and so on. The incidence of congenital heart disease is similar at home and abroad, with about 7 to 10 infants out of every 1,000 live births suffering from different kinds of congenital heart disease. With the continuous improvement of the level of cardiovascular surgery technology, the mortality rate of congenital heart disease is gradually decreasing, and it is now possible to perform cardiac surgery for children a few days after birth, and children who were previously inoperable can now be treated surgically; congenital heart disease that is now considered complex and cannot be treated surgically can be expected to be treated in the future with the improvement of medical technology.
1, the etiology of congenital heart disease:
The causes of congenital heart disease are mostly: the first two months of a woman’s pregnancy are the main stage in which the fetal cardiovascular system takes shape. During this period, viral infection, alcohol consumption, smoking, vitamin deficiency, radiation exposure and the use of some teratogenic drugs, as well as genetic factors may lead to abnormal development or developmental disorders of the cardiovascular system, resulting in congenital heart disease.
2.See the types of congenital heart disease:
There are many types of congenital heart disease and they are complex. According to the shunt caused by heart malformation, congenital heart disease is usually divided into two major categories: non-cyanotic and cyanotic congenital heart disease.
Non-cyanotic congenital heart disease malformation refers to the shunt from the left atrium, left ventricle or aortic system to the right atrium, right ventricle or pulmonary artery system, which does not cause unoxygenated venous blood to shunt to the body circulation system without cyanosis, referred to as “left-to-right shunt” congenital heart disease. The main types are ventricular septal defect, atrial septal defect, partial pulmonary venous malformation drainage, aortic constriction, and arteriovenous catheterization.
Cyanotic congenital heart disease malformation refers to the shunt from the right atrium, right ventricle or pulmonary artery system to the left atrium, left ventricle or aortic system, which means that the patient’s unoxygenated venous blood enters the body circulation through the cardiac malformation and manifests as cyanosis of the skin or lips. These congenital heart diseases are more complex, such as tetralogy of Fallot, pulmonary valve atresia, right ventricular double outlet, transposition of the great arteries, Eisenmenger syndrome, and severe pulmonary valve stenosis, etc. The degree of cyanosis worsens with increased activity.
3.Septal defect
The heart has two atria, right and left, with an intact interatrial septum separating the oxygen-depleted venous blood from the oxygen-rich arterial blood between them. Due to abnormal embryonic development, the septum does not close completely, resulting in shunting of blood from the left atrium with high intra-atrial pressure to the right atrium with low intra-atrial pressure, which increases blood flow to the right atrium and right ventricle and pulmonary circulation, easily causing upper respiratory tract infections and even pulmonary hypertension. Atrial septal defect is the most common congenital heart disease, accounting for about 21.4% of all congenital heart diseases.
Atrial septal defects are classified according to the diameter of the defect: small defects with a defect diameter of <1.5 cm; medium defects with a defect diameter of 1.5-2.5 cm; and large defects with a defect diameter of >2.5 cm.
Small atrial septal defects are often asymptomatic, and symptoms such as panic and shortness of breath often appear only in adulthood. A soft systolic murmur can be heard in the second intercostal space at the left edge of the sternum, and the electrocardiogram shows a right-sided or non-sided electrical axis, often with right bundle branch block. The chance of natural healing of atrial septal defect is very small, and surgery should be performed as soon as symptoms appear. Atrial septal defect of medium size or above should be operated as soon as possible after diagnosis to avoid the formation of pulmonary hypertension due to long-term “left-to-right shunt” and irreversible organic lesions of pulmonary vessels.
The surgery is performed under general anesthesia with extracorporeal circulation, and the repair method is determined by the size of the septal defect. Small defects smaller than 1.5 cm can be directly sutured; larger defects are patched with a pericardial piece or polyester piece to avoid the failure of the surgery due to excessive tension at the repair when the heart is beating after direct repair.
4.Septal defect
In normal human, there is a complete septum between the left and right ventricles, which separates the blood containing different oxygen in the left and right ventricles. If the fetal septal tissue is incompletely fused or poorly developed during the embryonic period, the presence of an abnormal channel between the ventricles is called a septal defect. Its prevalence is about 16% in congenital heart disease, and it is one of the most common congenital heart diseases.
As the pressure in the left ventricle is significantly higher than that in the right ventricle, it produces a shunt of blood from the left ventricle to the right ventricle during cardiac systole, resulting in increased blood flow in the pulmonary circulation and easily causing pulmonary hypertension.
Patients with ventricular septal defect are often prone to colds and difficult to feed when they are young. A rough systolic blowing murmur can be heard between the 3rd and 4th ribs at the left edge of the sternum, the electrocardiogram shows left deviation of the electrical axis, the chest radiograph shows increased pulmonary blood, and the echocardiogram can clarify the size and location of the defect. Since ventricular septal defect may heal naturally before 3 years of age, there is no urgency to operate on small ventricular defects before 3 years of age. If the defect does not heal after 3 years of age, surgery should be performed. The best time to operate for ventricular septal defect is from 3 to 6 years old, but for large ventricular septal defect, early appearance of pulmonary hypertension, should be operated as early as possible. after 3 years old, even small ventricular septal defect, due to the large pressure step difference between the left and right ventricles, pulmonary blood flow increases significantly, the long-term result is easy to cause pulmonary hypertension, and due to the impact of high-speed blood flow, easy to form infective endocarditis, so those diagnosed with ventricular septal defect should surgery.
Surgery is performed under general anesthesia with extracorporeal circulation. If the defect is very small, it can be closed by 1 or 2 stitches directly; for large defects, the method of polyester sheet or pericardial sheet repair is used.
5.Arterial stenosis
Pulmonary artery stenosis accounts for about 4% of congenital heart disease. Pulmonary stenosis in a broad sense includes pulmonary valve stenosis, subpulmonary valve (right ventricular outflow tract) stenosis, main pulmonary artery stenosis, and main branch pulmonary artery stenosis, of which pulmonary valve stenosis is the most common, accounting for about 75% of its total. Pulmonary stenosis causes reduced blood flow to the lungs. Mild pulmonary stenosis has no obvious symptoms, while moderate stenosis or above may cause shortness of breath, weakness, panic, dizziness, cyanosis or even syncope after exertion. A coarse systolic blowing murmur can be heard at the 2nd intercostal space on the left edge of the sternum, the electrocardiogram shows hypertrophic strain of the right ventricle, the chest radiograph shows reduced pulmonary blood, and the echocardiogram can clarify the degree of stenosis.
According to echocardiography, a pressure step difference of <30 mmHg between the proximal and distal ends of pulmonary stenosis is considered mild pulmonary stenosis; a pressure step difference of 30-60 mmHg is considered moderate stenosis; and a pressure step difference of >90 mmHg is considered severe stenosis. Mild pulmonary artery stenosis can be suspended without surgery; moderate stenosis or above should be treated with surgery. The best age for surgery is between 3 and 6 years old, because secondary changes in the heart caused by pulmonary stenosis increase the difficulty of surgery as age increases.
The surgery is performed under general anesthesia with hypothermic extracorporeal circulation, and the adhesions in the stenosis are cut away, and those with mast muscle bundles blocking blood flow should be removed. If the stenosis is severe, a patch widening approach can be used. In cases of pure valvular stenosis, the adherent valve junction can be cut open without extracorporeal circulation, and the valve area can be enlarged under the beating heart.
6.Pulmonary catheter insufficiency
During fetal life, there exists a traffic artery at the opening of the descending aorta and the left pulmonary artery, which is an important channel connecting the aorta and the pulmonary artery and supplying fetal blood nutrition, called the ductus arteriosus. The fetus grows and develops in the mother’s body without breathing, but obtains oxygen supplied by the mother through the placenta, so most of the blood draining from the fetal right ventricle into the pulmonary artery flows through the ductus arteriosus into the descending aorta. Within 2 weeks after birth, the ductus arteriosus should close on its own. If the ductus arteriosus does not close on time, the ductus arteriosus will not close, resulting in a large amount of aortic blood shunting to the pulmonary artery, which can easily lead to pulmonary hypertension in the early stage. Preterm infants have a high incidence of ductus arteriosus.
Arteriovenous ductus insufficiency can be heard as a continuous machine-like murmur at the second intercostal space on the left edge of the sternum, and the electrocardiogram shows a leftward deviation of the electrical axis, hypertrophic strain of the left ventricle, and a chest radiograph shows a significant increase in pulmonary texture. Echocardiography can clearly diagnose the presence of an abnormal channel between the descending aorta and the pulmonary artery.
After the diagnosis is clear, early surgery should be performed. The most appropriate age for surgery is 3 to 6 years old. However, thicker ductus arteriosus develops pulmonary hypertension in early childhood due to high fractional flow, and should be operated on promptly once the diagnosis is confirmed.
If the age is small, there is no obvious calcification or the catheter is long, the surgery can be performed by using the left posterior lateral incision, cutting and suturing the catheter or directly ligating it without extracorporeal circulation; if the age is large, there is obvious calcification or the catheter is funnel-shaped, a median chest incision should be taken under extracorporeal circulation for repair.
7.Fale’s triad
Farrer’s triad is a compound congenital heart malformation with pulmonary artery stenosis and atrial septal defect or oval foramen non-occlusion, resulting in a shunt phenomenon from the right atrium to the left atrium. Among cyanotic congenital heart diseases, its incidence is second only to that of tetralogy of Fallot.
As a result of pulmonary artery stenosis, the right ventricular ejection resistance increases significantly, the right ventricular compliance decreases, and the right atrial pressure is higher than that of the left atrium, resulting in a “right-to-left” shunt at the atrial level and cyanosis. Prolonged excessive right ventricular hypertension can lead to right heart failure. Patients may experience cyanosis, palpitations, shortness of breath, fatigue, and in severe cases, squatting, syncope, and chest pain. A jet murmur can be heard in the pulmonary valve area, oxygen saturation and arterial partial pressure of oxygen are reduced in blood gas analysis, and electrocardiogram shows right ventricular hypertrophy and strain. Echocardiogram can make a clear diagnosis, and once the diagnosis is clear, surgery should be performed as early as possible to avoid right heart failure and secondary changes of the heart.
The surgery is performed under general anesthesia with hypothermic extracorporeal circulation, and a patch is used to repair the atrial septal defect and unblock the pulmonary artery stenosis, which can be done by removing the hypertrophic muscle bundle or widening the patch.
8.Fale tetralogy of Fallot
Farrer tetralogy of Fallot is the most common malformation in cyanotic congenital heart disease, accounting for 13.7% of the total congenital heart disease, and it is also the type with the best surgical outcome and surgical success rate among cyanotic heart disease at present. The operative mortality rate of tetralogy of Fallot is about 1% to 5%.
Tetralogy of Fallot is composed of four malformations.
(1) pulmonary artery stenosis.
(2) septal defects.
(3) arterial straddling (meaning that the aorta rides over the left and right ventricles).
(4) ventricular (muscular) hypertrophy.
The clinical staging of tetralogy of Fallot is based on the degree of cyanosis, developmental status, activity limitation, hematocrit, oxygen saturation, pulmonary artery development and stenosis, and left ventricular size, and is classified as mild, moderate, or severe. The more severe the disease is, the earlier the surgery should be done to prevent the secondary changes in the heart from increasing when they grow up, making the surgery more difficult.
Patients with tetralogy of Fallot present with cyanosis, feeding difficulties, and developmental delays at an early age, and often die of heart failure and pulmonary infections at age 2. Patients often have pestle-like toes, systolic murmurs can be heard between the 2nd and 3rd ribs at the left edge of the sternum, and tremor can be palpated, hematocrit is increased, electrocardiogram shows rightward deviation of the electrical axis, hypertrophy of the right ventricle, chest radiograph shows reduced pulmonary texture and depression of the pulmonary artery segment, echocardiography can clearly diagnose and determine the size of the ventricular defect and pulmonary artery stenosis, and if the distal pulmonary artery does not show well, magnetic resonance examination or cardiac catheterization can be performed to make the diagnosis more accurate and clear. This makes the diagnosis more accurate and clear and facilitates the determination of the surgical approach.
The development of the pulmonary artery in patients with tetralogy of Fallot is very important for their prognosis and determines the surgical approach and outcome. If the pulmonary artery is poorly developed and the pulmonary valve annulus is not stenotic, the stenosis should be enlarged during surgery using a pericardial slice repair at the right ventricular outflow tract site and at the pulmonary artery site, respectively. If the pulmonary valve stenosis is also severe, two incisions need to be connected and a large pericardial slice is used to repair and expand the right ventricle, the pulmonary valve orifice and the pulmonary artery.
The surgery is performed under general anesthesia with hypothermic extracorporeal circulation. The hypertrophic muscle bundle of the right ventricular outflow tract is removed, and the outflow tract and pulmonary artery stenosis are widened with a patch at the same time. If the pulmonary valve annulus is narrow, the annulus should be cut off and the patch widened at the same time, and then the ventricular septal defect is repaired with a polyester sheet.
9.Aortic sinus aneurysm rupture
Aortic sinus rupture is called congenital aortic sinus aneurysm if the aneurysm breaks into the adjacent cardiac cavity, pericardium or pulmonary artery and produces intra-cavity shunts due to developmental defects or reduced support of the lower part of the aortic sinus.
Sinus aneurysm rupture can produce a large “left-to-right” shunt because it often breaks into the right atrium, causing an increase in the volume load of the heart chambers and leading to changes such as congestive heart failure. At the same time, aneurysm expansion causes expansion of the aortic valve annulus and displacement or prolapse of the valve leaflets, resulting in aortic valve insufficiency. If the aneurysm breaks into the pericardium, it can cause pericardial tamponade. This disease often has sudden onset of chest pain, palpitations, and dyspnea. A double-phase continuous heart murmur can be heard between the 3rd and 4th ribs at the left edge of the sternum, and there is often an increase in pulse pressure difference. The electrocardiogram shows left ventricular hypertrophy, strain, and various arrhythmias. Chest radiograph shows an enlarged heart, and the increased lung texture is not consistent with the degree of heart enlargement. Echocardiography may reveal dilatation of the aortic sinus and abnormal blood flow from the aortic sinus to the ventricular cavity. In cases where the diagnosis is unclear, ascending aortography can be used to clarify the diagnosis. Once the diagnosis is clear, early surgery should be performed to avoid cardiac failure or the development of infective endocarditis.
The surgery is performed under general anesthesia with hypothermic extracorporeal circulation, and the ruptured sinus aneurysm is sutured shut while the area is reinforced with a patch. If the sinus aneurysm affects the aortic valve so severely that the aortic valve cannot be shaped, then simultaneous aortic valve replacement surgery is required.
10.Aortic valve stenosis
The aortic valve is located at the junction of the aorta and the left ventricle, and has three normal leaflets with semilunar shaped leaflets and
They are half-moon shaped, and the edges of the leaflets are aligned with each other. If the aortic valve is bilobed and the junction is fused and the leaflets are thickened, this results in valve stenosis. This can cause increased left ventricular ejection resistance, decreased cardiac output, cardiomyocyte hypertrophy, and left ventricular insufficiency.
It can also cause tubular stenosis or membranous stenosis on or under the aortic valve, both of which are prone to myocardial hypertrophy, strain, and angina symptoms after activity, and require surgical treatment to relieve the stenosis.
Surgery is performed under general anesthesia with hypothermic extracorporeal circulation to remove the hypertrophic muscle bundle from the stenosis or to widen it with a patch. If the valve is severely involved, the aortic valve should be replaced at the same time.
11.Ectopic drainage
In a normal person, there are 4 pulmonary veins that converge the oxygenated blood from the lungs to the left atrium, which is then pulsed out through the left ventricle to supply the systemic tissues. If one or more branches of the pulmonary veins are not normally connected to the left atrium, but are connected to the right atrium or body venous system, it is called ectopic drainage of the pulmonary veins.
There are two types.
(1) Complete pulmonary vein ectopic drainage, which means that four pulmonary veins are not connected to the left atrium at all, but enter the corporal venous system.
(2) Partial ectopic pulmonary venous drainage, which is the type in which at least one pulmonary vein remains normally connected to the left atrium.
The clinical presentation is related to the volume of the shunt and the combination of other malformations. 80% to 90% of pulmonary vein ectopic drains are combined with an atrial septal defect. Patients present with cyanosis, increased respiration, poor feeding, recurrent pulmonary infections, systolic murmurs can be heard between the 2nd and 3rd ribs at the left sternal border, electrocardiogram shows a right-sided electrical axis, right ventricular hypertrophy, chest radiograph shows increased pulmonary texture, prominent pulmonary artery, enlarged right atrium and ventricle, and widened mediastinal shadow. For complicated cases that are difficult to diagnose clearly, cardiac catheterization and ventriculography can be used. After the diagnosis is clear, surgery should be performed promptly, and attention should be paid to the combination of other malformations that should be corrected at the same time.
The surgery is performed under general anesthesia with hypothermic extracorporeal circulation, and a pericardial or polyester sheet is used to repair the ectopically draining pulmonary veins into the left atrium and to close the atrial septal defect.