Congenital patent ductus arteriosus

Introduction to congenital patent ductus arteriosus The arterial catheter is originally a normal blood flow channel between the pulmonary artery and the aorta during the fetal period. Since the lung does not have respiratory function, the pulmonary blood from the right ventricle enters the descending aorta through the catheter, and the blood of the left ventricle enters the ascending aorta. Therefore, the arterial catheter is necessary for the special circulation mode of the embryonic period. After birth, the lungs swell and bear the function of gas exchange. The pulmonary circulation and the systemic circulation perform their duties. Soon, the catheter is closed by itself due to waste. If it does not close continuously, it constitutes a pathological condition called patent ductus arteriosus. Surgery should be performed to interrupt its blood flow. When the patent ductus arteriosus is present in the cyanotic heart disease with reduced pulmonary blood flow, the catheter is an important condition for its survival. Patent ductus arteriosus is a more common congenital cardiovascular malformation, accounting for 12 to 15% of the total number of congenital heart diseases, such as about twice as much sex as men. About 10% of cases coexist with other cardiovascular malformations. basic knowledge The proportion of illness: 0.001%-0.005% (5% to 10% of congenital heart disease) Susceptible people: no special people Mode of infection: non-infectious Complications: pseudoaneurysm

Causes of congenital patent ductus arteriosus

Genetic factors (60%)

Genetics is the main cause. Any factors affecting the development of the heart embryo during the fetal period may cause cardiac malformations, such as pregnant women with rubella, influenza, mumps, Coxsackie virus infection, diabetes, hypercalcemia, etc., pregnant mothers contact radiation; pregnant mother Take anticancer drugs or drugs such as methylprednisolone.

Pathogenesis

The fetal arterial catheter develops from the back of the sixth aortic arch, forming the fetal blood circulation aorta, the physiological pathway between the pulmonary arteries, the fetal pulmonary vesicles all collapse, no air, and no respiratory activity, thus the pulmonary blood vessels The resistance is very large, so most of the venous blood discharged from the right ventricle cannot enter the pulmonary circulation for oxygenation. Since the pulmonary artery pressure is higher than the aorta, most of the blood entering the pulmonary artery will flow into the aorta through the arterial artery and then through the umbilical artery. The placenta is exchanged with the maternal blood in the blastoderm and then into the umbilical vein for reflux into the fetal blood circulation.

Congenital patent ductus arteriosus prevention

The operative mortality caused by massive hemorrhage during arterial catheter closure depends on the wall of the catheter, the surgical procedure of the closed catheter, and the skill of the surgeon. It should be within 1%, and the catheter is simply ligated or clamped. Postoperative catheter recanalization is likely, the recanalization rate is generally above 1%, the recanalization rate after pad ligation is lower than the former two, the long-term effect of arterial catheter closure, whether there is secondary pulmonary vascular secondary preoperative The lesions and their extent, patients who have undergone surgery before pulmonary vascular disease can be completely recovered, life expectancy is normal; pulmonary vascular disease is severely irreversible, postoperative pulmonary vascular resistance is still high, right heart load is still heavy, the effect is better difference.

Congenital patent ductus arteriosus complications Complications pseudoaneurysm chylothorax

The disease mainly has some surgical complications, including the following:

1, intraoperative major bleeding: the most serious and often lead to death accidents, the occurrence of major bleeding is more concealed, usually in the posterior or upper corner of the catheter, large bleeding, the surgeon should remain calm, quickly press the bleeding site with your fingers, temporarily After hemostasis, the blood in the surgical field is sucked. If the descending aorta has been freed (not to be clamped under the clamp), the strip can be pulled up, and the arterial forceps can be used to block the upper and lower blood flow of the aorta, while clamping the catheter and then cutting Catheter, looking for bleeding break El, and then with the cut end together with 3-0 or 4-0 non-invasive polypropylene suture for continuous or 8-shaped intermittent suture, such as the descending aorta did not first free, with the finger pressing temporary hemostasis, immediately after heparin To establish an extracorporeal circulation, insert the artery into the artery of the left subclavian artery and the descending aorta or the left femoral artery respectively, and insert the venous drainage tube into the right atrial appendage or right ventricular outflow tract to establish a rapid flow of blood. The temperature is lowered, then the descending aorta adjacent to the catheter is freed, the guide of the descending aorta is clamped, and the suture catheter and the rupture are cut.

2, left recurrent laryngeal nerve paralysis: the cause of postoperative hoarseness, in addition to tracheal intubation caused by throat vocal edema: mainly in the operation of traction, causing left recurrent laryngeal nerve edema, or ligation of the slit catheter when the nerve is damaged, resulting in Early postoperative water or fluid sputum cough, hoarseness, prednisone, vitamin B1 and B6 and physiotherapy, edema can be resolved within 2 to 3 weeks, the sound can be closed after the nerve injury, although the right vocal cord Shift compensation, so that eating does not cause cough, but the sound is low and hoarse is permanent.

3, catheter recanalization: generally occurs after catheter ligation, mainly due to insufficient ligation of the lumen, or the ligation line is loose, or due to ligature tearing the endometrium of the catheter, with pseudocanal aneurysm, intratumoral rupture and recanalization The incidence rate is about 2%. Clinically, typical heart murmurs are heard in the early postoperative period or several days later. Color Doppler ultrasound confirms that there is a shunt between the pulmonary arteries. In the past, the direct cut suture method was used because of scars around the catheter. Tissue, adhesion is tight, free catheter is difficult, easy to cause rupture, so it is necessary to take a greater risk of surgery. At present, there are two more appropriate methods for catheter recanalization: First, catheter tamponade is simple and easy to use, which is the preferred method; The second is the transcatheter closure of the catheter through the pulmonary artery during deep hypothermic cardiopulmonary bypass. Although the operation is complicated, it is safe.

4, pseudoaneurysm: This is a very serious complication, caused by local infection or surgical injury to the catheter, the clinical manifestations of fever 2 weeks after surgery, hoarseness or hemoptysis, murmur above the left front chest, chest Radiography showed that the pulmonary artery segment protruded into a blocky shadow. After the diagnosis, a single operation should be performed to prevent sudden rupture and massive hemorrhage. The operation should be performed under cardiopulmonary bypass. The extracorporeal circulation catheter treatment can be used. The aortic end can be directly sutured or used. Artificial fabric patch repair, or artificial blood vessel transplantation.

5, chylothorax: rare, mainly due to anatomical aortic arch descending and left subclavian artery root injury chest catheter, early detection; after re-into the chest, find the chyle leakage outlet in the above site to be sutured, later found, Conservative therapy, if not effective, then cut the right lower chest, suture the thoracic duct next to the upper semi-singular vein of the diaphragm.

Symptoms of congenital patent ductus arteriosus Common symptoms Systolic murmur water rushing capillary pulsation clubbing (toe) Neonatal heart failure purpura

Clinical manifestations of patent ductus arteriosus: mainly depends on the amount of blood flow from the aorta to the pulmonary artery and whether secondary pulmonary hypertension is produced and to what extent. Light can have no obvious symptoms, and severe heart failure can occur. Common symptoms are nausea, shortness of breath, fatigue, and prone to respiratory infections and dysplasia. Since the widespread use of antibiotics, bacterial endarteritis has been rare. Late pulmonary hypertension is severe, and when the reverse shunt occurs, the lower body purpura appears. In the case of a congenital patent ductus arteriosus, a typical sign is a continuous, machine-like murmur that is heard in the second intercostal space on the left sternal border, accompanied by tremors. The second sound of the pulmonary artery is hyperactive, but it is often obscured by loud noises. For those with larger flow rates, diastolic murmurs due to relative stenosis of the mitral valve can still be heard in the apical region. The blood pressure shows that the systolic blood pressure is mostly in the normal range, and the diastolic blood pressure is lowered, so that the pulse pressure is widened, and the blood vessels of the extremities have water pulse and gunshot sound.

Infants and young children can only hear systolic murmurs. In the late stage of pulmonary hypertension, the murmurs are more variable, and only systolic murmurs, or systolic murmurs, disappear and are replaced by diastolic murmurs of the pulmonary valve insufficiency (Graham Steell murmur).

Examination of congenital patent ductus arteriosus

(1) X-ray examination

According to the thickness of the arterial catheter and the size of the flow, the posterior anterior chest can show normal or light to moderate enlargement of the heart, the left heart edge is downward, and the left side is extended to the left. The aortic node can be funnel-shaped or comma-shaped. The pulmonary artery cone is straight or bulged; the hilar vascular wall is deepened, the pulmonary artery is light to severely widened, and the lung field texture is thickened.

(2) ECG examination

Those with small flow rate can be normal or the left axis of the electric axis is biased. If the flow rate is large, the left ventricle is high voltage or left ventricular hypertrophy. If the pulmonary artery is obviously high, the left and right ventricular hypertrophy are shown.

(3) Echocardiography

Two-dimensional echocardiography can directly display the communication of the main artery, the patent ductus arteriosus of the pulmonary artery and can measure the inner diameter. Doppler ultrasound can show the turbulent spectrum from the aorta to the pulmonary artery, and measure the volume of the flow according to the area of the split beam. The level of pulmonary artery pressure.

(4) Cardiac catheterization

Pulmonary blood oxygen level is higher than 0.5ml above the right ventricle, suggesting that the pulmonary artery has a left-to-right shunt. The greater the difference in blood oxygen content, the larger the partial flow rate, and the flow rate can be calculated. The pulmonary artery pressure can be normal, or Different degrees of elevation, such as the cardiac catheter through the catheter into the descending aorta to the level of the diaphragm, can more clearly diagnose.

(5) ascending aorta angiography

The left lateral continuous film shows that the ascending aorta and the aortic arch are widened, the descending aorta is narrowed, the inner edge of the isthmus is prominent, and the contrast agent flows into the pulmonary artery through this, and shows the shape, inner diameter and length of the catheter.

Diagnosis and diagnosis of congenital patent ductus arteriosus

There are many left-to-right shunt intracardiac malformations on the left sternal border that can hear the same continuous machine-like murmur or near-continuous two-stage heart murmur, which is difficult to identify and must be identified before establishing a patent ductus arteriosus diagnosis. The main malformations are now discussed as follows in the order of incidence.

(1) High ventricular septal defect combined with aortic valve prolapse

When the high ventricular septal defect is large, it is often accompanied by aortic valve prolapse malformation, leading to aortic valve insufficiency, and causing corresponding signs. Clinically, double-stage murmur is heard on the left sternal border, and the diastolic phase is water-like. Conducting upwards, but sometimes similar to continuous murmurs, it is difficult to distinguish. At present, color echocardiography has been routinely examined for heart disease. In this disease, aortic valve prolapse and aortic blood flow can flow back into the left ventricle. Ventricular septal defect is diverted from the left ventricle to the right ventricle and pulmonary artery. For further definitive diagnosis, retrograde ascending aorta and left ventricle angiography may be performed. The former may indicate that the ascending aorta contrast agent flows back into the left ventricle, while the latter shows left ventricular contrast agent. Dividing the right ventricle and pulmonary artery through the ventricular septal defect, it is not difficult to make a differential diagnosis.

(two) rupture of aortic sinus

The disease is not uncommon in China. The clinical manifestations are similar to those of patent ductus arteriosus. Continuous heart murmurs of the same nature can be heard, but the location and conduction direction are slightly different. Those who have broken the right ventricle are biased to the apex. Broken right atrium is biased to the right side, such as color Doppler echocardiography showing aortic sinus malformation and its shunt to the ventricular and pulmonary or atrial cavity can be identified, plus retrograde ascending aorta angiography Establish a diagnosis.

(C) coronary artery fistula

This type of coronary artery malformation is rare, and the same continuous murmur as the patent ductus arteriosus can be heard with tremor, but the site is lower and is on the medial side. Doppler color Doppler can show the location where the arterial fistula is located and communicates with it. In the ventricular cavity, retrograde aortic angiography is more likely to show enlarged coronary artery main branches, or branching and sputum.

(four) aortic-pulmonary septal defect

Very rare, often with the patent ductus arteriosus, and has the same continuity of murmurs and peripheral vascular features, but the murmur site is low to the medial side, careful echocardiography can find its shunt site in the ascending aorta root, Retrograde ascending aorta angiography is easier to confirm.

(5) Coronary artery ectopic

The right coronary artery originates from the pulmonary artery and is a rare congenital heart disease. The heart murmur is also continuous, but it is lighter and superficial. Doppler ultrasonography is helpful for differential diagnosis. Retrograde ascending aorta angiography is continuous. The radiograph shows an abnormal opening and direction of the coronary artery and a collateral circulation of the gyrus, which can be clearly diagnosed.

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