Patent ductus arteriosus

Introduction to patent ductus arteriosus Patent ductus arteriosus (PDA) is one of the common types of congenital heart disease, accounting for 15% of the total number of congenital heart disease, more common in women. 10-15 hours after the baby is born, the arterial catheter begins to functionally close. 2 months to 1 year after birth, the vast majority are closed, and those who are still not occluded after 1 year of age are patent ductus arteriosus. basic knowledge The proportion of illness: the incidence rate of infants and young children is about 0.002%-0.005% Susceptible population: occurs 10-15 hours after the baby is born Mode of infection: non-infectious Complications: pulmonary hypertension chylothorax

Cause of patent ductus arteriosus

Fetal development environment (28%):

Intrauterine viral infection is the most important cause of congenital heart disease, of which the most common infection with rubella virus, followed by Coxsackie virus infection. Other causes such as amniotic membrane disease, fetal compression, early pregnancy threatened abortion, maternal malnutrition, diabetes, and the use of radiation and cytotoxic drugs in early pregnancy are the causes of congenital heart disease.

Genetic (12%):

Genetics is the main internal cause. Any factors affecting heart embryo and fetal development during the fetal period may cause cardiac malformations, such as pregnant women with rubella, influenza, mumps, Coxsackie virus infection, diabetes, hypercalcemia, etc. Pregnant mothers are exposed to radiation; pregnant mothers take anticancer drugs or drugs such as methyl sulphate. In a family, brothers and sisters or parents and children with congenital heart disease, as well as many genetic abnormalities of chromosomal abnormalities and cases of cardiovascular vascular malformations, indicating that the disease has genetic factors.

Premature delivery (15%):

Premature birth is an important cause of congenital heart disease. Newborns born below 2,500 grams are more likely to have congenital heart disease.

Plateau environment (10%):

Low altitude oxygen pressure is one of the causes of congenital heart disease. The prevalence of congenital heart disease in the Qinghai-Tibet Plateau is much higher than that in the plain area.

Other (10%):

Older mothers (over 35 years of age) have a higher risk of developing tetralogy of Fallot and Down's syndrome.

Embryology and 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.

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.

Complications of patent ductus arteriosus Complications pulmonary hypertension chylothorax

The prognosis of this disease is generally good, many patients are asymptomatic and some of them are as long as normal, but heart failure can occur in patients with unconventional arterial ducts. The prognosis of patients with pulmonary hypertension and right to left shunt is poor. Individual patients have pulmonary or ambulatory artery. Catheter rupture can quickly die, severe cases of pneumonia in infants, heart failure, long-term can lead to pulmonary hypertension, obstructive pulmonary vascular disease, and even blood flow from the pulmonary artery into the aorta (called Eisenmenger syndrome).

Some of the major surgical complications of this disease include the following:

1, intraoperative major bleeding:

The most serious accident that often leads to death, the breach of the bleeding is more concealed, usually in the posterior or upper corner of the catheter, there is a major bleeding, the surgeon should remain calm, quickly press the bleeding site with your fingers, temporarily stop bleeding, suction surgery Wild blood, if the descending aorta has been freed (not to be clamped under the clamp), the strip can be pulled up (Fig. 28-07), and the two arterial clamps are 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, except for tracheal intubation caused by laryngeal vocal edema: mainly during intraoperative traction, causing left larynx recurrent nerve edema, or ligating the slitting catheter to damage nerves, resulting in early postoperative influx or fluid Cough, hoarseness, prednisone, vitamin B1 and B6, and physiotherapy, edema can be resolved within 2 to 3 weeks. After the nerve injury, the sound can be turned off by the right vocal cord, so that eating is not good. Coughing, but the sound is low and hoarse is permanent.

3, the catheter re-pass:

Generally occurs after catheter ligation, mainly due to insufficient ligation of the lumen, or loosening of the ligature, or tearing the intima of the catheter due to the ligature, and pseudocanal aneurysm, and the intratumoral rupture and recanalization, the incidence rate is about 2 %, clinically heard typical heart murmurs early or several days after surgery, color Doppler confirmed the main, there is a shunt between the pulmonary arteries, in the past, the use of direct cut suture closure treatment, due to scar tissue around the catheter, adhesion tight, free The catheter is difficult and 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: one is catheter tamponade, which is simple and easy to use, and is the preferred method; Lower transcatheter closure of the catheter, the operation is more complicated but safer, see later.

4. Pseudoaneurysm:

This is a very serious complication caused by local infection or surgical injury of the catheter. The clinical manifestations are fever 2 weeks after surgery, hoarseness or hemoptysis, murmur above the left front chest, chest radiograph showing pulmonary artery segmentation Blocky shadows should be performed after diagnosis. In case of sudden rupture and massive hemorrhage, the operation should be performed under cardiopulmonary bypass. The aortic end can be directly sutured or repaired with artificial fabric patch, or Artificial vascular grafting.

5, chylothorax:

Rarely, mainly due to anatomical aortic arch descending and left subclavian artery root damage to the thoracic duct, early detection; after re-introduction, find the chyle leakage outlet at the above site to be sutured, later found, then conservative treatment, If it does not work, then cut the right lower chest and suture the thoracic duct next to the upper semi-singular vein of the diaphragm.

Symptoms of patent ductus arteriosus Common symptoms Meridian capillary pulsation systolic murmur water rushing pulse femoral artery sounding clubbing finger (toe) Ascending aortic root ring narrowing continuous machine-like murmur angiography see double ball sign

First, the symptoms: small flow, often asymptomatic.

A large amount of flow, because the aortic pressure is higher than the pulmonary artery pressure, there is a continuous left-to-right shunt in the whole cardiac cycle, the pulmonary circulation blood flow increases, the pulmonary artery and its branches expand, and the blood flow to the left atrium and left ventricle increases accordingly. , left atrium, increased diastolic load, ascending aorta dilatation, the size of the sub-flow depends on the thickness of the aortic catheter lumen and the pressure gradient between the main and pulmonary arteries, a large number of left to right shunt, can cause pulmonary hypertension, In the advanced stage, if there is obstructive pulmonary hypertension, the pulmonary artery pressure approaches or exceeds the aortic pressure, the shunt decreases, stops or right-to-left shunt, and right ventricular hypertrophy, purpura and clubbing (toe), due to shunt level On the far side of the descending aortic left subclavian artery, the lower limbs of the purpura are obvious, left to right shunt at the level of the aorta, aortic diastolic blood pressure is reduced, and a series of peripheral vascular signs such as increased pulse pressure appear.

Second, the signs:

The apex beats and shifts to the left, the heart sounds to the left to the left, and the left sternal border has a loud continuous murmur on the lateral side of the intercostal space. It is transmitted to the left upper neck and back, accompanied by systolic or continuous fine tremor, and the pulmonary artery appears. After high pressure, only systolic murmurs may be heard, the second sound of the pulmonary artery is hyperthyroidism and splitting, and the pulmonary valve may have a relative diastolic murmur. When the flow rate is large, the blood flow increases due to the mitral valve orifice. The apex has a short diastolic mid-term murmur, which may have peripheral vascular signs, including: increased carotid pulsation, increased pulse pressure, water pulse, capillary pulsation, gunshot sound and Du's sign.

Arterial catheterization

First, X-ray: light can be normal, the flow rate is large, the pulmonary vascular shadow is increased, the pulmonary artery is bulging, the pulsation is enhanced, the left atrium, the left and right ventricles are enlarged, and the aorta is dilated.

Second, ECG: moderate diverts have left ventricular hypertrophy, larger diverts have left and right ventricular hypertrophy, left atrial hypertrophy.

3. Echocardiography: left atrium, left ventricle enlargement, aortic widening, and can show the diameter and length of the patent ductus arteriosus. Doppler ultrasound can measure the systolic and diastolic turbulence spectrum at the distal end of the main and pulmonary arteries. .

Fourth, cardiac catheterization: the average blood oxygen content of the pulmonary artery is higher than the right ventricle 0.5% volume, pulmonary hypertension has increased to varying degrees, sometimes the cardiac catheter can enter the descending aorta from the pulmonary artery through the patent ductus arteriosus, if necessary, for aortic angiography, It can be seen that the aorta and the pulmonary artery are simultaneously developed, and the position, shape and size of the catheter are clearly defined.

Diagnosis and differential diagnosis of patent ductus arteriosus

Differential diagnosis

(1) Congenital aorta-pulmonary septal defect is a dysplasia of the aortic septum in the fetal period, which causes the aortic-pulmonary artery to be left with a defect. The clinical manifestation is similar to the large patent ductus arteriosus. The differential diagnosis is extremely difficult and continuous. Sexual machine sounds are louder and the position is lower (lower intercostal space) can be used as a reference for differential diagnosis, but it is not very reliable. The more reliable differential diagnosis method is the right heart catheterization when the cardiac catheter enters the aorta from the pulmonary artery. In the ascending department, retrograde ascending aorta angiography showed simultaneous elevation of the ascending aorta and common pulmonary artery. Two-dimensional echocardiography showed widening of the common pulmonary artery and aorta. There was a defect communication between them, which also contributed to the diagnosis, such as the occurrence of significant pulmonary hypertension. When there is a right-to-left shunt with purpura, the blood oxygen content of the lower extremity arteries is equal, which is not the same as the patent ductus arteriosus.

(2) Aortic sinus aneurysm is broken into the right heart by a congenital malformation, syphilis or infective endocarditis and other causes of aortic sinus aneurysm, can erode and penetrate into the pulmonary artery, right atrium or right ventricle , resulting in a left-to-right shunt, the continuous machine sound murmur is similar to the patent ductus arteriosus, but the position is lower between the two ribs, the disease has a history of sudden onset, such as sudden palpitations, chest pain, chest tightness Or chest discomfort, feeling tremors in the left chest, etc., followed by the performance of right heart failure, can help diagnose.

(C) the supraventricular supraventricular ventricular septal defect with aortic valve insufficiency identification points see this section "ventricular septal defect".

(4) Other conditions sufficient to cause similar continuous machine sound murmurs in the left front chest, such as coronary arteriovenous fistula, left upper lobe pulmonary arteriovenous fistula, left anterior chest wall arteriovenous fistula, left neck neck jugular vein camping sound, etc. Also pay attention to identification.

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