AORTA
NORMAL VALVEThe aortic valve shows three thin and delicate cusps. The coronary artery orifices can be seen just above.The endocardium is smooth, beneath which can be seen a red-brown myocardium. The aorta above the valve displays a smooth intima with no atherosclerosis
This is the tricuspid valve. The leaflets and thin and delicate. Just like the mitral valve, the leaflets have thin chordae tendineae that attach the leaflet margins to the papillary muscles of the ventricular wall below.
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Aortic Stenosis
Clinical Presentation:
Most are asymptomatic, but symptoms can include chest pain and syncope. Thirteen percent of patients can get congestive heart failure in the first year of life, congestive heart failure rarely develops later in life.
Etiology/Pathophysiology:
Occurs at the level of the aortic valve in 60-75% of cases. It is associated with a bicuspid aortic valve in greater than 50% of cases. Supravalvular stenosis is rare, and is almost always associated with infantile hypercalcemia/Williams syndrome.
Left ventricular hypertrophy develops in response to increased ventricular end systolic pressure and dilation does not occur until the stenosis is complicated by ventricular decompensation
Imaging Findings:
The CXR is usually normal in mild cases. In more severe cases, in time, you can get left ventricular hypertrophy and then left ventricular dilation. Post stenotic dilation of the ascending aorta is the most persistent radiologic finding, due to the jet of blood shooting through the stenotic valve and striking the lateral aortic wall. "Left ventricular configuration" is when there is a concavity to the left mid-heart border combined with a prominent lower left heart border.
Coarctation of the Aorta, Infantile
Clinical Presentation:
Infantile type presents in the neonate or young infant with congestive heart failure and bounding upper extremity pulses and diminished lower extremity pulses. This infantile type is also known as preductal coarcation. The infantile type is the most frequent cause of pulmonary venous hypertension and congestive heart failure that presents in the second and third week of life.
Etiology/Pathophysiology:
Usually caused by a congenital indentation in the posterior wall of the aorta that usually is distal to the origin of the left subclavian artery at the level of the ductus arteriosus. Infantile type coarctation causes a diffuse narrowing while adult type coarctation causes a focal narrowing.
Seventy-five percent of patients have a bicuspid aortic valve, and ASD / VSD / PDA / mitral valve deformities can also be seen.
Since the ductus arteriosus is still often open, a pressure gradient is not present across the coarctation, and collateral circulation does not develop. Right ventricular volume overload and dilation develops because almost all blood reaching the descending aorta must come through the ductus arteriosus from the right ventricle. As the ductus begins to close, a pressure gradient develps across the coarctation and the relatively underdeveloped left ventricle begins to fail. Increased left atrial pressure is then transmitted to the pulmonary veins with progressive venous engorgement and pulmonary edema. Post stenotic dilation of the aorta is not seen due to prenatal lack of flow across the coarctation.
Coarctation of the Aorta, Adult Type
Clinical Presentation:
Adult type is usually not diagnosed until late childhood or early adulthood when hypertension and a difference in arm and leg pulses is detected on routine physical.
Etiology/Pathophysiology:
Usually caused by a congenital indentation in the posterior wall of the aorta that usually is distal to the origin of the left subclavian artery at the level of the ductus arteriosus. Infantile type coarctation causes a diffuse narrowing while adult type coarctation causes a focal narrowing.
The collatateral circulation is via the internal mammary arteries, the costocervical trunk, and the intercostal arteries.
Seventy-five percent of patients have a bicuspid aortic valve, and ASD / VSD / PDA / mitral valve deformities can also be seen.
Imaging Findings:
The adult type often has intercostal rib notching due to collateral flow through dilated pulsatile intercostal arteries and it is seen in 75% of older children with coarctation. It is unusual to see rib notching before 6 years of age. It is seen in the 3rd - 9th ribs because the 1st and 2nd ribs intercostal arteries come from the thyocervical trunk which is above the coarctation. Irregular wavy densities seen on the lateral film reflect dilation of the internal mammary arteries.
Another sign in the adult type is the "3" sign which is created by a prominent left subclavian artery, the coarctation and post stenotic dilation of the descending aorta. The barium swallow shows a reversed "3" which represents the aortic impression on the esophagus above and below the coarctation.
Ebstein Anomaly
Clinical Presentation:
Can present at any age with cyanosis. There may be chest pain or palpitations related to cardiac arrythmia. Life expectany is 10-20 yrs with death due to right sided heart failure.
Etiology/Pathophysiology:
Is due to a low insertion of the tricuspid valve which divides the right ventricle into proximal and distal chambers. The proximal atrialized division works as a receiving chamber with the right atrium. The more distal ventricular division acts as pumping chamber. A functional obstruction at the level of the tricuspid valve exists due to asynergous diastole of atrium during systole of the atrialized right ventricle. The tricuspid valve is often deformed, leading to tricuspid regurgitation. A right to left interatrial shunt is often present. The clinical course depends on the amount of tricuspid valve deformation / obstruction and the amount of right to left shunt.
Imaging Findings:
On the CXR cardiomegaly with a prominent right heart border and decreased pulmonary vasculature is seen. A "box like" configuration to the heart can be seen in older children due to a combination of right atrial enlargement and outward displacement of the right ventricular outflow tract.
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