Briefly, pulmonary atresia can be divided into two types depending on the presence or absence of a ventricular septal defect, namely pulmonary atresia with an intact ventricular septum and pulmonary atresia with a combined ventricular septal defect. It is a rare congenital heart disease with no gender differences.
I. Pathology
The right ventricular wall is very thick and the tricuspid orifice is small; because the right ventricle is a blind cavity, blood returns to the right atrium during contraction; blood returning from the vena cava to the right atrium can only enter the left atrium, left ventricle and aorta through the unclosed foramen ovale or atrial septal defect. Blood from the pulmonary circulation comes from the arterial ducts or the corporal pulmonary artery collateral circulation (MAPCAs).
The concomitant ventricular septal defect, also known as pseudo-common-artery trunk, is the most severe type of tetralogy of Fallot. Due to pulmonary valve atresia or agenesis, there is no access between the right ventricle and the pulmonary artery, and the pulmonary trunk itself may be atretic or dysplastic. All the blood from the left and right ventricles is injected into the aorta, and the blood from the pulmonary circulation comes from the arterial ducts or bronchial arteries.
Clinical manifestations
The clinical manifestations of ventricular septal defect are similar to those of tetralogy of Fallot, except that the cyanosis appears earlier than in tetralogy of Fallot and occurs several days after birth, the systolic murmur is often lighter, the continuous murmur from the unclosed ductus arteriosus or bronchial collateral circulation may be heard in the chest and back, the early systolic jet sound can often be heard after the first heart sound, and the second heart sound at the bottom of the heart is enhanced and single. The lobe of the lung may show a reticulo-bronchial collateral circulation shadow. The diagnosis can be confirmed by echocardiography.
The clinical picture of intact ventricular septum resembles severe pulmonary stenosis, and most children die within the first few days of life. If the ductus arteriosus remains open and the hypoxia is mild, the child may survive for several weeks, but in general the cyanosis is significant, the hypoxia is severe and there are paroxysmal episodes, easily combined with heart failure and hepatomegaly. The jugular vein is only wave-high. A continuous murmur can often be heard, from an unclosed arterial duct or only a mild systolic murmur, from an incomplete tricuspid valve closure, a single 2nd heart sound at the base of the heart, due to the disappearance of the pulmonary valve closure sound, a mild or extremely enlarged cardiac shadow on X-ray, a marked depression in the lumbar region of the heart, and a reduced vascular shadow in the pulmonary field. The electrocardiogram shows hyperacute P waves. In right ventricular dysplasia, left ventricular hypertrophy is seen, but the electrical axis is often in the normal range or mildly rightward, a point different from the leftward deviation of the electrical axis in tricuspid atresia. Echocardiography can confirm the diagnosis. It can show pulmonary atresia, right ventricular cavity size, ventricular wall thickness, tricuspid valve morphology and opening/closing function, and measure the size of the foramen ovale or atrial septal defect. Cardiac catheterization may reveal increased pressure in the right atrium and right ventricle. Cardiovascular angiography may confirm that the right ventricle is a blind cavity and that contrast enters the left atrium, left ventricle, and aorta from the right atrium through the atrial septal defect, and may also reveal the passage of contrast into the pulmonary circulation.
Examination
1.X-ray examination, electrocardiogram, echocardiogram, cardiovascular imaging, spiral CT examination.
2.Cardiovascular imaging and spiral CT examination can further clarify the type of intracardiac malformation, the development of pulmonary arteries, the size and number of the combined pulmonary collateral arteries and whether there is traffic between them and the intrinsic pulmonary arteries. In particular, cardiovascular imaging can clarify the traffic between the collateral pulmonary arteries and the intrinsic pulmonary arteries as well as the blood supply of the corresponding pulmonary segments.
IV. Treatment
Pulmonary atresia with intact ventricular septum should be treated surgically once diagnosed. Postnatal intravenous prostaglandin E1 is administered to delay ductus arteriosus closure. The decision is based on the morphology of the right heart as seen on echocardiography, especially the size of the funnel section, etc. If the conditions are suitable, biventricular repair surgery can be chosen; if not, surgery is mostly performed in a staged procedure with first body-pulmonary artery shunt or simultaneous pulmonary valvotomy under extracorporeal circulation; stage 2 establishes the right ventricular to pulmonary artery flow channel at the age of 3 to 5 years and closes the interatrial traffic and extracardiac shunt.
The treatment strategy for pulmonary atresia combined with ventricular septal defect is more complex, and in terms of current outcomes, pulmonary atresia combined with ventricular septal defect remains one of the most challenging areas of congenital heart surgery worldwide, especially in patients with combined MAPCAs, for which the basic research is not yet in-depth and the individual patient varies greatly, leading to a diversity of surgical approaches with The results are all less than ideal.
1, there are intrinsic pulmonary arteries, catheter-dependent type and no MAPCAs, this type accounts for the majority, the arterial catheter supplies the pulmonary artery, patients generally have well-developed coincident intrapericardial pulmonary arteries, suitable for one-stage closure of VSD. there are various methods to assess the size of the pulmonary artery, the commonly used indicators are.
(1) MeGoon ratio: It is generally accepted that repair of the VSD can be considered when the value > 1.2 to 1.5.
(2) Nakata index: ≥150 mm2/m2 can be considered for radical surgery. Nakata index often better reflects the development of pulmonary artery than McGoon ratio; when radical surgery is required without conditions, right ventricular outflow tract reconstruction or body pulmonary artery bypass can be considered.
2, there are intrinsic pulmonary arteries and MAPCAs, this type is more common, surgical treatment currently has three main views.
(1) One-stage fusion via median incision to restore as much normal physiological function of the pulmonary segment as possible and to strive for simultaneous closure of the VSD.
(2) Since MAPCAs and even intrinsic pulmonary arteries will have varying degrees of stenosis after fusion, leading to poor long-term results, it is thus considered that MAPCAs should not be fused, but rather right ventricular outflow tract reconstruction or body pulmonary artery bypass should be performed to promote the development of intrinsic pulmonary arteries, and radical surgery should be performed after conditions are met.
(3) In between, MAPCAs with traffic to the innate pulmonary artery can be closed surgically or interventionally, and MAPCAs that supply blood alone should undergo fusion. Currently, most centers still perform fusion of MAPCAs as a combined procedure with concurrent radical or palliative surgery when necessary. In this type, we can still rely on the aforementioned indicators to determine whether radical surgery can be performed, and those who do not meet the conditions for radical surgery should undergo right ventricular outflow tract reconstruction or body-pulmonary artery bypass and/or simultaneous pulmonary artery fusion.
3.No intrinsic pulmonary artery and MAPCAs as the only blood supply. This type is the least common, with difficult surgery and poor results. The current mainstream view emphasizes the following points.
(1) One-stage fusion via median incision.
(2) Restoring as much of the normal physiological function of the lung segment as possible.
(3) Avoidance of artificial materials as much as possible (except for the right ventricular pulmonary artery duct).
(4) Early surgery; a single universal surgical strategy is still lacking for this variable disease.