(A) Atrial septal defect
Atrial Septal Defect (ASD) is one of the most common congenital heart diseases, accounting for 17.7% to 21.4% of all congenital heart diseases. The incidence ratio is 1.6:1 in males and females, and ASDs include two-hole type (also called secondary hole type) and one-hole type (also called primary hole type).
Imaging performance
1.X-ray plain film: The plain film of typical ASD often shows increased pulmonary blood, a “mitral valve” type heart, protruding pulmonary artery segment, enlarged right atrium and ventricle of the heart, and reduced or normal aortic node. In small cases of ASD, the heart and lungs may appear approximately normal or only mildly altered.
2, right heart catheter: catheter through the right atrium directly into the left atrium, can suggest that there is traffic between the two atria, often need to be distinguished from the oval foramen nonisolation. The oxygen saturation of the right atrium is 9% higher than that of the superior and inferior vena cava, suggesting a left-to-right shunt at the atrial level. Right heart catheterization is still limited in small ASDs, but it is more helpful in ASDs with combined pulmonary hypertension.
3, cardiovascular imaging: generally four-chamber (left anterior oblique position 45. +30. ~40.) right upper pulmonary venography is used. Contrast agent travels down the interatrial septum, and when the body of the left atrium is not yet filled, the contrast agent has already passed through the ASD into the right atrium, so the site and size of the ASD can be clearly shown.
4.MDCT: Single-layer cross-sectional enhancement scan can show ASD, which shows that the left and right atrial septum are connected by contrast. The dilatation of the right atrium, ventricle and pulmonary artery can also be observed. In addition, blood flow examination is meaningful for the determination of postoperative residual shunt.
5, MRI: Cardiac gated SE sequence transverse axis position, is the commonly used MRI scan technique to show ASD. Long-axis and short-axis imaging of the left ventricle is also useful for observing the anatomy of the atrial septum and determining the size of ASD. Mostly, the middle of the right atrium (equivalent to the oval fossa) is the center of the scan, and two to three layers are scanned upward and downward, showing continuous interruption and absence of atrial septal tissue on the two adjacent layers, then ASD can be diagnosed, while small ASD is often difficult to be sure.
6.Echocardiography: M-type echocardiography is characterized by an increased right heart volume load. 2DE can directly show most ASDs, find interrupted septal echoes, and measure the size of the defect. Doppler can qualitatively and quantitatively reflect the hemodynamic status of atrial shunts, increased right atrial, ventricular and pulmonary blood flow in ASD, etc. TEE can clearly show the number, size, width and thickness of defect edges, and the presence of other malformations in each area. C-Echo is useful for determining bidirectional shunts or even right-to-left shunts at the atrial level in ASD with severe pulmonary hypertension. After intravenous contrast injection, the contrast echo is seen to pass from the right atrium into the left atrium through the defect.
Diagnosis, differential diagnosis, and comparative imaging
The diagnosis can be established by physical examination when a grade 2-3 systolic blowing murmur is heard at the left sternal border between 2 and 3 ribs , the second tone of the pulmonary artery is split; electrocardiogram shows incomplete right bundle branch conduction block; plain film shows more pulmonary blood and enlarged right atrium and ventricle; echocardiogram shows increased right heart volume load and interrupted septal echo.
Small ASDs should be differentiated from partial pulmonary venous malformation drainage, while ASDs combined with severe pulmonary hypertension need to be differentiated from ventricular septal defects combined with severe pulmonary hypertension. Echocardiography helps to confirm the diagnosis.
MRI and CT are generally rarely used in ASD alone. Plain films can only show increased pulmonary blood flow, heart shape and atrial enlargement, and can make a preliminary diagnosis in typical cases. Echocardiography can directly show the location, size, number and peripheral relationship of ASD, and can observe the abnormal hemodynamics, which is currently the preferred non-invasive examination method. Right heart catheterization and cardiovascular angiography are limited to difficult cases of ASD combined with severe pulmonary hypertension, where the diagnosis is unclear by noninvasive examination, and some interventional patients.
(ii) Ventricular septal defect
Ventricular Septal Defect (VSD) is one of the common congenital heart diseases, and its incidence is the first in congenital heart diseases, about 20%. Depending on the location of the defect, VSD can be divided into three types, namely perimembranous, funicular and myocardial VSD.
Imaging performance
1.X-ray plain film: The plain film of typical VSD shows a mitral valve type heart with moderate to high enlargement, mainly involving the left and right ventricles, mostly the left ventricle is more significant, or accompanied by mild enlargement of the left atrium; increased pulmonary blood, dilated pulmonary hilar artery, some patients can see signs such as distorted and thinning texture of peripheral pulmonary vessels; moderate to high projection of pulmonary artery segment; normal or reduced aortic node. These changes suggest a moderate to large left-to-right shunt or a VSD with moderate to right-right pulmonary hypertension.
VSD with a small amount of left-to-right shunt mostly showed mild enlargement of the heart and ventricles, with a predominantly left ventricle; mild increase in pulmonary blood; non-convex pulmonary artery segments; and normal aortic nodes. A small number of small VSDs with normal cardiopulmonary X-rays, but with typical clinical signs, are called Roger’s disease.
In VSD combined with severe pulmonary hypertension, the heart enlargement is not obvious, but the right ventricle enlargement is more prominent, and the right atrium enlargement, if the pulmonary vascular texture from the middle band is obviously thinning or even reduced, it often shows the sign of pulmonary blood reduction; the aortic node is mostly reduced. If the patient appears cyanosis, it is Eisenmenger syndrome.
2.Right heart catheter: The oxygen saturation of the right ventricle is 5% higher than that of the right atrium, suggesting a left-to-right shunt at the ventricular level.
Cardiovascular angiography: Mostly four-chamber left ventriculography is used. The contrast agent enters the right ventricle immediately after filling the left ventricle, which is a conclusive sign of left-to-right shunt at the ventricular level. According to the density of the right ventricular filling, the width of the contrast agent through the septum, the site, the direction of injection and the location of the earliest filling of the right ventricle, the anatomical site, size and quantity of VSD can be accurately determined.
4, MDCT: Enhanced scan can show VSD. continuous cross-sectional images, more suitable for observing the VSD in various parts. application of flow-type scan, rapid mass injection of contrast can show the site, size, morphology and dynamic changes in blood flow of VSD.
MRI: Cardiac gated SE sequence, transaxial position is the basic position to show the site and size of VSD, supplemented by sagittal, coronal and oblique position can more comprehensively determine the direction of VSD expansion and help to detect concurrent malformations. fast imaging of GRE sequence and MRI movie can complement the SE method to improve the detection rate of VSD. MRI movies can also calculate the fractional flow of VSD.
6. Echocardiography: ME shows increased left heart volume load. If accompanied by pulmonary hypertension, the a-wave of pulmonary valve motion curve disappears and opens in a V or W shape. 2DE can show the size of VSD; fractionation of partial VSD can be made in the short axis part of the aorta. Color Doppler has a high value for VSD of about 2 mm to 20 mm. In the absence of pulmonary hypertension, the right ventricular surface of the ventricular septum can be detected with red and colorful mosaic of high-speed turbulent shunts, and the diameter of the VSD can be measured; in the presence of pulmonary hypertension, right-to-left blue shunts can be detected at the site of the defect. In large VSDs, because the pressure difference between the two ventricles is small and the resistance is low or even almost equal to zero, the colored shunt bundle is basically laminar, with a pure red left-to-right shunt and a pure blue right-to-left shunt. In patients with cyanosis that is a complex malformation with VSD, the use of acoustic imaging is helpful in the diagnosis of VSD and right-to-left shunt.
Diagnosis, differential diagnosis and comparative imaging
On physical examination, a grade 3 systolic blowing murmur can be heard between the 3 and 4 ribs at the left edge of the sternum, and systolic tremor is mostly palpable; the second pulmonary artery sound is normal or hyperactive; electrocardiogram shows left ventricular hypertrophy or biventricular hypertrophy; plain film shows more pulmonary blood and enlarged left atrium and ventricle; echocardiogram shows increased left heart volume load and interrupted septal echo, etc. The diagnosis can be confirmed.
VSD with severe pulmonary hypertension is sometimes confused with ASD with pulmonary hypertension, and the diagnosis should be made by echocardiography.
For VSD with typical radiographic signs, plain films can mostly suggest the diagnosis, but for small VSD or those with severe pulmonary hypertension, radiography is quite limited, and plain films are used for preliminary or screening diagnosis. Echocardiography, mainly 2DE and Doppler techniques, can observe the size, location and hemodynamic changes of VSD, and can also show concurrent malformations, which has become the preferred and commonly used imaging technique for the diagnosis of VSD. MRI, EBCT or spiral CT are helpful for the diagnosis of VSD, but they are large devices and are second-line techniques. Although right heart catheterization and cardiovascular angiography are still reliable methods for the diagnosis of VSD, because they are invasive techniques, they are mainly used in the diagnosis of VSD with severe pulmonary hypertension, complex or compound malformations and some interventional patients.
(iii) Patent ductus arteriosus
Patent ductus arteriosus (PDA) is one of the most common congenital heart diseases, accounting for about 20% of congenital heart diseases, and the incidence is more in women than in men, about 3:1.
Imaging performance
1.X-ray: The plain film of typical PDA shows increased pulmonary blood, enlarged left ventricle, widened aortic node in 90% of cases, and nearly half of them can be seen as “funnel sign”. This sign refers to the funnel-shaped expansion of the descending aortic arch on the orthopantomograph and the abrupt inversion of the descending aorta below it at the intersection with the pulmonary artery segment (Figure 5-15). A fine PDA plain radiograph shows normal or mildly increased pulmonary blood and a heart size that is mostly in the normal range. With pulmonary hypertension there may be varying degrees of bulging of the pulmonary artery segment, dilatation of the hilar artery, distortion and thinning of the peripheral pulmonary vascular texture, and enlargement of both ventricles or even predominantly the right atrium and ventricle.
2, right heart catheter: Pulmonary artery oxygen saturation is higher than 3% of the right ventricle, which can indicate a left-to-right shunt at the bottom of the heart; at the same time, the pulmonary artery pressure can be measured directly and the left-to-right shunt flow can be calculated. In most cases, the catheter can enter the descending aorta directly from the pulmonary artery through the unclosed arterial catheter, which has important value for the qualitative diagnosis of PDA.
3, cardiovascular angiography: Generally, it is appropriate to do the left side of the aortic arch descending angiography. The main sign is that the main pulmonary artery fills immediately after the filling of the descending aortic arch; if there is a dilution sign of contrast at the upper end of the descending aorta, it is a corroboration of a right-to-left shunt at the level of the pulmonary artery. Similarly, if the descending aorta fills early during main pulmonary angiography, it also suggests a clear right-to-left shunt at this level.
4.MDCT: Enhanced scans can show PDA, which appears in cross-section as a conduit between the left pulmonary artery and the descending aorta.
5.MRI: Cardiac gated SE sequences are suitable to show the usual PDA, which is shown in transaxial position (ascending aorta-left pulmonary artery level) as an abnormal duct between the left pulmonary artery and descending aorta with no or low signal.
6.Echocardiography: ME shows the manifestation of increased left heart volume load; 2DE in the short axis of the aorta can show the abnormal duct between the main and pulmonary arteries, and can measure the thickness and length of the lumen and the type of PDA. Color Doppler can detect the abnormal bundle of red and colorful mosaic in the anomalous duct between the main pulmonary artery and descending aorta, and can determine the internal diameter of PDA. Continuous Doppler can obtain a high-speed blood flow spectrum.
Diagnosis, differential diagnosis and comparative imaging
On physical examination, a double-phase continuous machine-like murmur is heard between the 2nd and 3rd ribs at the left edge of the sternum; ECG shows left ventricular hypertrophy; plain film shows increased pulmonary blood, widened aortic node, which may have the “funnel sign” and enlarged left ventricle; echocardiography shows an abnormal duct between the main pulmonary artery and the descending aorta, which can make a clear diagnosis.
PDA should be differentiated from VSD combined with aortic valve insufficiency and other fundic flow malformations, such as coronary artery fistula, aortopulmonary septal defect and aortic sinus aneurysm rupture. Echocardiography, MRI and EBCT are quite helpful in the diagnosis of these diseases.
In typical PDA, plain film is valuable for its qualitative diagnosis and analysis of secondary pulmonary hypertension. However, this method cannot directly show PDA itself, so it is still a preliminary or screening diagnostic technique. EBCT and MRI are rarely used clinically for simple PDA. 2DE combined with Doppler technique is a commonly used and effective non-invasive examination, which can be used as a basis for pre-surgical diagnosis of PDA in general, and is especially helpful for fine PDA Doppler technique. To date, contrast combined with catheterization remains the “gold standard” for PDA morphology and hemodynamic diagnosis. Because it is an invasive technique, it is generally used for the diagnosis of PDA in difficult cases or complicated malformations, especially for the detection of small PDA and the determination of combined severe pulmonary hypertension. In fact, imaging has now become an integral part of PDA intervention.