What Is Patent Ductus Arteriosus?
What is the difference in fetal blood circulation?
Fetus in the mother can't breathe, oxygen is through the umbilical artery in the mother's placenta, so the lung circulation is closed, but the four chambers of the heart has begun to work normally, the right ventricular blood into the pulmonary artery after can't enter the lung circulation is like a river downstream closed.
This requires a spillway to channel, the spillway is arterial catheter.
Why is the arterial catheter closed?
In the fetus, the pulmonary artery pressure is obviously higher than that of the aorta due to the closed pulmonary circulation, and blood enters the aorta through an arterial catheter.
Immediately after the birth of the fetus, as a cry lung filled with gas, also marks the pulmonary circulation began to work normally, right ventricular blood can enter the pulmonary circulation through the pulmonary artery, don't need ductus arteriosus this spillway, ductus arteriosus to complete the mission, need to natural closure.
What is patent ductus arteriosus?
Normally, the ductus arteriosus will close 10 hours after birth, but this time the closure is not stable and there is still the possibility of reopening.
After 8 weeks it cannot be reopened because the ductus arteriosus will be completely closed. If the ductus arteriosus is not closed after eight weeks, it is called delayed closure of the ductus arteriosus; if it is not closed after six months, it is called patent ductus arteriosus.
Is the incidence of patent ductus arteriosus high?
The incidence rate of patent ductus arteriosus in infants is about 3/10,000, accounting for about 20% of congenital heart diseases. The incidence rate of female is obviously higher than that of male, about 3: 1.
What Is The Cause Of Patent Ductus Arteriosus?
At present the specific reason of PDA is still unclear, mainly has the following several views:
- The anastomosis angle of arterial catheter and aorta can affect closure, and acute angle prevents blood from easily entering the arterial catheter to facilitate closure. The obtuse angle make it easy for blood to enter that arterial catheter and is not conducive to closure.
- In neonates, low oxygen content in the blood may weaken the contraction of arterial ducts and affect their closure.
- If the mother has rubella during the third trimester of pregnancy, the fetus is susceptible to congenital cardiovascular defects.
- Patent ductus arteriosus is genetically related.
What Are The Symptoms Of Patent Ductus Arteriosus?
Are there any symptoms of patent ductus arteriosus?
The symptoms are related to the severity of the disease and determined by the size of the PDA. PDA has a small diameter and a small partial flow, but it may have no obvious symptoms. PDA has a large diameter and large partial flow rate. Children are vulnerable to respiratory tract infection, growth retardation and squatting. Heart failure can occur in infancy in severe cases, which is life-threatening.
What is the squat phenomenon?
It is manifested as the children suddenly bend their legs and squat down for a while while walking or running normally, and then recover to walk or run normally after more than ten seconds. This phenomenon occurs repeatedly.
Crouching, if any, usually indicates a serious illness in the child, probably due to a giant PDA that has already developed pulmonary hypertension. The crouching of the child can reduce blood reflux in the lower limbs, right ventricular load and pulmonary artery pressure.
Why does patent ductus arteriosus cause pulmonary hypertension?
The aortic pressure after birth is higher than the pulmonary artery pressure, so if the ductus arteriosus is patent, blood from the aorta (left ventricle pumping blood) will flow to the pulmonary artery (right ventricle pumping blood), which is called left-to-right shunt.
For example, if PDA exists for a long time, a series of changes will occur in pulmonary blood vessels, and the increased pressure will prevent blood from continuing to shunt, which is called pulmonary hypertension. Eventually the pulmonary artery pressure even exceeds the aortic pressure, and blood shunts from the pulmonary artery to the aorta, called right-to-left shunting.
Why is pulmonary hypertension caused by patent ductus arteriosus cyanotic?
When right-to-left shunt occurs in PDA, hypoxic blood in the pulmonary artery flows into the aorta and reaches the lower body, resulting in hypoxia and cyanosis in the lower body tissue. The blood in the upper body is shunted before it is not mixed with hypoxic blood, so cyanosis does not occur in the upper body under general conditions.
How To Check For Patent Ductus Arteriosus?
What is a giant patent ductus arteriosus?
It means that the diameter of the narrowest part of PDA is larger than a certain value: for children ≥ 6 mm and for adults ≥ 10 mm There are more giant PDAs in children and fewer in adults because giant PDAs are usually more symptomatic and prone to heart failure.
They either recover completely after surgical treatment in childhood or struggle to survive into adulthood because of worsening symptoms. If the patient survives to an adult stage, he/she will often suffer from heart failure and cyanosis in the lower body due to pulmonary hypertension, and his/her life is at risk at any time.
What is the simplest way to find patent ductus arteriosus?
If parents find that the baby is prone to cold, developmental delay or crouching, the simplest way is to let the doctor listen to the baby with a stethoscope for heart murmur.
This is not only applicable to PDA, but also applicable to other congenital heart diseases such as atrial septal defect and ventricular septal defect, and many congenital heart diseases are discovered in this way. However, it does not rule out that some PDA with very small diameters cannot hear noises, and other examination methods are required to be clear at this moment.
What is the most necessary test for the diagnosis of patent ductus arteriosus?
Echocardiography, also known as cardiac color ultrasound. This examination can basically confirm the diagnosis. It can not only identify the presence of PDA, but also measure the diameter of PDA, estimate the level of pulmonary artery pressure, determine the type of shunt, and evaluate whether the right heart function is good, and whether other congenital heart diseases are combined.
Another routine echocardiogram is also needed after PDA surgery to see if there is residual shunt and to evaluate the surgical effect.
How To Prevent Patent Ductus Arteriosus?
How to prevent patent ductus arteriosus.
- Avoid rubella in the first 3 months of pregnancy.
- Physical examinations as soon as possible after birth.
- Try to avoid premature birth.
- At present, there is no effective prevention method for genetic patent ductus arteriosus.
How To Treat Patent Ductus Arteriosus?
Can patent ductus arteriosus heal itself?
Very few patients close between 6 and 12 months, but if they remain unclosed for more than 12 months, the prevailing clinical view is that natural closure will not be possible.
What should I do after patent ductus arteriosus is found?
If the time is not more than 8 weeks, don't try so hard, a large part of the baby after 8 weeks arterial catheter will naturally close, so as long as there is no special symptoms within 8 weeks, give priority to with observation (such as found baby crying at night, don't want to eat should immediately seek medical treatment).
If it is not closed after 8 weeks, the treatment plan should be discussed with a specialist. For example, if the diameter of PDA is small (less than 3 mm), the color Dopplar ultrasound can be re-examined regularly every three months. Attention should be paid to preventing cold at ordinary times and excessive exercise should not be allowed. When the child is about 3 years old, PDA intervention occlusion will be performed at an elective date.
For example, if the diameter of PDA is larger (greater than or equal to 3 mm), we will need to consult the doctor if early surgery is needed when the child reaches the age of 6 months, so as to avoid the impact on surgery caused by the increased pulmonary artery pressure. For a large PDA (6 mm or larger), the cardiac surgeon needs to be consulted to see if surgical ligation is required as soon as possible.
How to treat patent ductus arteriosus?
Medical transcatheter closure can be used (preferred) or surgical ligation of the patent ductus arteriosus after thoracotomy (used when transcatheter closure is not possible or after failure of interventional closure).
Either treatment needs to be performed before right-to-left shunt. If right-to-left shunt occurs, surgery opportunity will be lost, and the disease will enter an irreversible fast lane. The only option is to adopt conservative treatment to control pulmonary hypertension, which has poor effect and high cost.
Why can't we operate after right-to-left shunt of patent ductus arteriosus?
When right-to-left shunting occurs, it indicates that long-term pulmonary hematocele, vascular remodeling and increased pulmonary artery pressure are irreversible. Because the pulmonary artery pressure has exceeded the aortic pressure, the arterial catheter then becomes a shunt channel. If it is blocked or ligated, there will be no place to release the pulmonary artery pressure, and the disease will accelerate to deteriorate.
What is the indication of transcatheter closure of patent ductus arteriosus?
- Left-to-right shunt without concomitant surgical PDA for cardiovascular malformations.
- They were usually ≥ 6 months of age and weighed ≥ 4 kg (coil closure) and ≥ 5 kg (mushroom umbrella closure).
- There was still residual shunt after surgery.
- Coils are suitable for small diameter PDA patients, usually less than 3 mm The mushroom umbrella is widely used, the size of the diameter can be used.
What is the optimal surgical age for transcatheter closure of patent ductus arteriosus?
Generally, interventional occlusion is feasible in children older than 6 months until right-to-left shunting occurs.
The best operation time is 2 ~ 3 years old. If elevated pulmonary arterial pressure (mean pressure ≥25 mmHg) was found, the earlier treatment was preferred. If the diameter of PDA is very small (less than 1 mm), without any symptoms and without affecting the growth and development, long-term observation can also be carried out, and then surgical treatment is carried out when a trend of increased pulmonary artery pressure is found.
What are the contraindications for transcatheter closure of patent ductus arteriosus?
- Body weight < 4 kg.
- Right-to-left shunting occurs.
- Combined with congenital heart disease requiring cardiac surgery.
- Repeated pulmonary infections with recent uncontrolled infection or untreated septicemia.
- Venous thrombosis of the lower extremities or thrombosis of the right atrium.
- Malignant diseases with a combined survival hope of less than 3 years.
- PDA is the life channel of some complex congenital heart diseases. For example, PDA combined with aortic coarctation cannot seal the arterial catheter.
What is the therapeutic effect of transcatheter closure of patent ductus arteriosus?
Satisfactory results have been achieved in the interventional treatment of PDA with coil and mushroom umbrella occluder.
The success rates of the coil sealing technique were 89%–94.3% and the mushroom umbrella sealing technique was 97.1%–100%. The unsuccessful cases were mainly because the narrowest diameter of PDA was too large or too small.
If it is too large, surgical treatment can be considered as a supplement, and if it is too small and without any symptoms and pulmonary hypertension, it can be temporarily observed and regularly reviewed.
Why are patients with patent ductus arteriosus prone to hemolysis and thrombocytopenia after surgery?
At present, there is still controversy in the medical field.
It is generally accepted that there may still be residual shunt after the plugging of giant PDA. The blood will flow faster through the residual shunt, and the red blood cells will be damaged due to mechanical collision. To put it bluntly, the red blood cells will be crushed, and hemolysis will occur. In serious cases, there is life risk. The typical manifestation is that the urine is like soy sauce.
At the same time, after the huge PDA was blocked, a large number of platelets were deposited on the blocking device and did not circulate in the blood, resulting in thrombocytopenia. The typical manifestation is spontaneous bleeding of the nose or gums of the patient. In severe cases, gastrointestinal bleeding and intracranial hemorrhage may occur, and blood transfusion treatment is required if necessary.
A large PDA is usually found preoperatively, and immediate family members are usually asked to prepare blood as a precaution.
How should the success of transcatheter closure of patent ductus arteriosus be evaluated?
After the sealing umbrella was placed surgically, the contrast agent was pushed in through a hollow catheter in the aorta. If the sealing was successful, the contrast agent would not reach the pulmonary artery from the arterial catheter.
If the procedure is unsuccessful or there is residual shunting, contrast can be seen entering the pulmonary artery through an arterial catheter. The family members after the operation can request to have a look at this picture and have a good idea.
Under what circumstances does patent ductus arteriosus require surgical treatment?
Indications of surgical treatment for PDA are very extensive, and surgical treatment can be adopted as long as there is no special case such as right-to-left shunt. The simple understanding is that patients who are suitable for PDA interventional occlusion are also suitable for surgical treatment, while patients who are not suitable for PDA interventional occlusion may be suitable for surgical treatment.
It is recommended that the patient first consult the cardiology department to understand whether interventional occlusion is suitable, and if not, go to the cardiology department for consultation. Surgical treatment is also needed for failure of cardiac interventional procedures, or for persistent thrombocytopenia and non-rebound of giant PDA despite successful interventional procedures.
Is the patient with patent ductus arteriosus the same as normal person after surgery?
If the operation was successful and there were no intraoperative or postoperative complications, and there were no residual shunts by echocardiography after three months and no abnormalities in cardiac function, the patient with PDA would have been truly cured. No matter it is lifestyle, diet, exercise, or future growth, natural life expectancy are the same as ordinary people.
From this point, it can be seen that, with the exception of a few small PDA (less than 1 mm) that can be observed for a long time, timely intervention or surgical treatment is necessary for most patients.
What happens if a patient with patent ductus arteriosus loses the opportunity to operate?
This condition is more common in adults at present. The reason is that many patients did not pay enough attention to the severity of PDA a few decades ago and did not take timely surgical treatment. As a result, the condition developed into right-to-left shunt and the operation opportunity was lost.
At this time, only drugs are selected to control pulmonary hypertension and delay the progression of the disease, and drugs such as bosentan, iloprost and sildenafil can usually be selected for treatment.