Overview
Ventricular septal defect is the most common form of congenital heart disease. It is a condition in which the septum is embryologically underdeveloped, forming abnormal traffic and creating a left-to-right shunt at the ventricular level, and can exist alone or as part of a complex cardiac malformation.
Etiology
Classification of congenital ventricular septal defects
In the fifth to seventh week of embryonic life, the myocardial septum is formed from the apical part of the ventricle from the bottom up and from the bulbous ridge from the top down, and the membranous septum from the endocardial cushion at the atrioventricular valve is fused with the first two to form a complete ventricular septum, which completely separates the left and right ventricular chambers. The defect is usually a single defect, but occasionally multiple defects are seen.
According to the location of the defect, it can be divided into five types.
1, supraventricular crest defect: located in the right ventricular outflow tract, above the supraventricular crest and below the main and pulmonary valves, in a few cases combined with incomplete closure of the main and pulmonary valves.
2, subventricular crest defect: located in the septal membrane, this type is the most common, accounting for about 60-70%.
3, posterior septal defect: located in the right ventricular inflow tract, posterior to the tricuspid septal valve, accounting for about 20%.
4, myocardial defect: located in the apical part, it is a myocardial trabecular defect, the systolic time septal myocardial contraction makes the defect smaller, so the left-to-right shunt flow is small.
5, common ventricle: both septal membrane and myocardial parts are undeveloped, or multiple defects, which are less common.
Symptoms
Many children are found during visits for lung infections in infancy, and others come to the clinic after a heart murmur is detected during a physical examination.
1. Symptoms Small defects may be asymptomatic. Larger defects are prone to recurrent respiratory infections in infants and young children due to high fractional flow, and may also show symptoms of cardiac insufficiency, such as shortness of breath, enlarged liver, feeding difficulties, and poor growth.
2. Signs The more typical signs are a grade III-IV rough jet systolic murmur with palpable tremor and hyperactive and splitting second pulmonary valve sounds heard between the 3 and 4 ribs at the left edge of the sternum. The murmur may be reduced when the left-to-right shunt is reduced due to pulmonary hypertension, while the second tone in the pulmonary valve area is markedly hyperactive and split.
Ventricular septal defect treatment care.
I. Internal treatment
Mainly prevent and treat infective endocarditis, pulmonary infection and heart failure.
Second, surgical treatment
1.Surgical principles
(1) In view of the possibility of natural closure of ventricular defect, children with small defect and young age can be observed until 2-3 years old.
(2) Very small ventricular defect, asymptomatic, chest X-ray and electrocardiogram are normal, generally do not need surgical treatment. However, regular outpatient follow-up should be performed.
(3) For children with ventricular defect without the possibility of self-healing and without pulmonary hypertension, elective surgery can be performed at the age of 1~4 years. (2) The main surgical method: interventional treatment or intracardiac direct view ventricular defect repair under medium and low temperature extracorporeal circulation can be used.
(4) funicular defects, especially bicuspid subvalvular defects, should be radically treated before the age of 2 years heart to prevent the occurrence of aortic valve prolapse.
(5) Some large ventricular defects, recurrent pneumonia, heart failure, unsatisfactory control by active medical treatment, regardless of age and weight restrictions, should be treated by early surgery. If the technical and equipment conditions are inadequate, pulmonary artery circumferential reduction can be performed first to relieve symptoms. Radical surgery should be performed after 3-6 months.
(6) Children with severe resistance pulmonary hypertension and clinical cyanosis should be a contraindication to surgery.
(7) Regular postoperative follow-up, pay attention to the presence or absence of residual shunts and recovery of cardiac function.
2. Indications for surgery
In huge ventricular septal defect, 25%-50% die within 1 year of age due to pneumonia and heart failure. Therefore, infants with recurrent heart failure should be treated with defect repair. About half of the small defects may close on their own and may be observed until 10 years of age before surgical treatment is considered, except for complications of bacterial endocarditis. Very small defects may not require surgery for life. Infants and children with fractional flow greater than 50% or with increased pulmonary artery pressure should be operated early to prevent a sustained rise in pulmonary hypertension. If severe obstructive pulmonary hypertension has been achieved, it is a counter indication for surgery.
3.Surgical method
Under general anesthesia with tracheal intubation, a median sternotomy is performed to establish extracorporeal circulation. After blocking the cardiac circulation, the anterior wall of the right ventricular outflow tract is incised, which can reveal various types of ventricular septal defects, but there is some damage to the myocardium. This can affect the right heart function and damage the right bundle branch. Currently, a trans-right atriotomy approach is used, which is better for revealing membrane defects. For higher defects, a transpulmonary route is preferred. Smaller defects with fibrous tissue at the edges can be sutured directly, while those with defects >lcm can be patched with polyester woven sutures. The conduction bundle goes through the lower edge of the membranous defect, and the septal posterior defect is easily mended by sutures, which should be avoided and sutured against the root of the septum.
With the increasing safety of cardiovascular surgery and the increasing attention to the aesthetics of intraoperative trauma incision, minimally invasive small incision surgery has been gradually favored by the majority of patients in recent years.
4. Postoperative treatment
(1) For those who have obvious pulmonary hypertension before surgery, it is advisable to apply respirator continuously until the next morning after surgery, and if the respirator cannot be removed 48 hours after surgery, tracheotomy should be done instead of endotracheal intubation.
(2) Patients with pulmonary hypertension often have postoperative circulatory instability and need to maintain blood pressure with positive inotropic drugs.
(3) If Ⅲ° AV block occurs after surgery, the pacing performance should be ensured. In some cases, it is a transient injury of the conduction bundle, and the conduction function will be restored automatically within a few days.
5.Surgical effect
(1) It depends on the severity of the patient’s disease, the early or late stage of the disease, as well as the degree of perfection of the operation and the appropriateness of postoperative treatment. In patients without obvious pulmonary hypertension, the operative mortality rate is within 2%.
(2) For those who have serious secondary pulmonary vascular lesions before surgery, the incidence of respiratory and circulatory complications after surgery is high, and the mortality rate is also significantly higher; the recovery depends on the degree of their pulmonary vascular lesions; if the lesions have become irreversible, the prognosis is poor.
Preventive care for ventricular septal defect.
1, should arrange a reasonable living system for the child, not only to enhance exercise, improve the body’s resistance, but also to rest properly and avoid overworking. If the affected child is competent, he or she should try to live and study with normal children, but should prevent strenuous activities. At the same time, children should be educated to have confidence in the treatment of the disease and to reduce pessimism and fear.
2. Indoor air should be circulated. Windows should be opened regularly in winter to enhance air convection. Children with persistent cyanosis should avoid high indoor temperature, which may lead to sweating and dehydration.
3. Give a high protein, high calorie, vitamin-rich diet to enhance physical fitness. Avoid overfeeding. Children with cyanotic heart disease must be given enough water to avoid dehydration that may lead to thrombosis. Infants with congenital heart disease are more difficult to feed, and they tend to stop sucking because of shortness of breath when sucking, and they are prone to vomiting and sweating a lot, so a dropper can be used when feeding to reduce the physical exertion of the child. Gently lay down on the side after feeding to prevent vomit inhalation and suction asphyxia.
4. Avoid emotional excitement of the child, try not to make the child cry, and reduce unnecessary stimulation so as not to increase the burden on the heart.
5.Keep the bowel movement smooth. For children with cyanotic type, do not use too much force when defecating, so as not to increase the burden on the heart. If there is no stool for two days, use open plug laxative to pass stool.
6, congenital heart disease children are prohibited to infuse a large number of fluids, if you must infuse, the drip rate must be slow, to prevent increased burden on the heart, resulting in heart failure.
7, children with tetralogy of Fallot take a squatting position, and often take the initiative to squat for a moment when walking or playing. This is because squatting can make the symptoms of hypoxia relieved, if the child has this phenomenon, parents must not forcibly pull the child up.
8.For children who usually have good heart function and activity endurance, they should receive vaccination according to the time, but after vaccination, they should observe more systemic and local reactions for timely treatment.
9. Children with congenital heart disease are weak and susceptible to infections, especially respiratory diseases, and are prone to heart failure, so they should be carefully cared for, and their clothes should be increased or decreased with the change of seasons. If a family member has an upper respiratory tract infection, isolation measures should be taken, and children should be taken to public places as little as possible. Once the child becomes infected, the infection should be actively controlled.
10. If the child is found to have shortness of breath, irritability, rapid heart rate, difficulty in breathing and other symptoms, heart failure may occur, and should be sent to the hospital promptly.