Abstract
This chapter provides a brief review of complex congenital heart disease. Included is a general approach to complex anatomy as well as examples of coarctation, patent ductus arteriosus, tetralogy of Fallot, transposition of the great arteries, and Ebstein anomaly.
Keywords
complex congenital heart disease, tetralogy of Fallot, transposition of the great arteriess
Introduction
Due to improvements in surgical techniques and medical therapies in recent years, there has been an increase in survival to adulthood in those with complex congenital heart disease. While complex congenital heart disease requires a careful and individualized approach, there are some fundamental assessments that should occur based on anatomic diagnosis.
Segmental Anatomy
In patients with complex congenital heart disease, it is important to first assess the segmental anatomy of the heart. A systematic approach, which evaluates each level of blood flow—from the inferior vena cava (IVC) to the descending aorta—can be useful. Heart position is often best assessed with a subcostal sweep evaluating the location of the cardiac organ and the direction of the ventricular apex. This approach determines levocardia (leftward apex) from mesocardia (midline apex) from dextrocardia (rightward apex) ( 
). A careful evaluation of the systemic venous flow, atrial position, atrioventricular valves, ventricular morphology, pulmonary venous return, great vessel location, aortic arch, and descending aorta anatomy should follow. A brief review of the more common congenital heart lesions is presented here. A review of atrial septal defect (ASD) and ventricular septal defects (VSDs) is in Chapter 43 , Chapter 44 . The full scope of complex congenital heart disease is addressed in the congenital echocardiography references listed at the end of this chapter.
Segmental Anatomy
In patients with complex congenital heart disease, it is important to first assess the segmental anatomy of the heart. A systematic approach, which evaluates each level of blood flow—from the inferior vena cava (IVC) to the descending aorta—can be useful. Heart position is often best assessed with a subcostal sweep evaluating the location of the cardiac organ and the direction of the ventricular apex. This approach determines levocardia (leftward apex) from mesocardia (midline apex) from dextrocardia (rightward apex) ( 
). A careful evaluation of the systemic venous flow, atrial position, atrioventricular valves, ventricular morphology, pulmonary venous return, great vessel location, aortic arch, and descending aorta anatomy should follow. A brief review of the more common congenital heart lesions is presented here. A review of atrial septal defect (ASD) and ventricular septal defects (VSDs) is in Chapter 43 , Chapter 44 . The full scope of complex congenital heart disease is addressed in the congenital echocardiography references listed at the end of this chapter.
Patent Ductus Arteriosus
The ductus arteriosus is a connection of the descending aorta and pulmonary arteries that functions to deliver oxygenated blood from the placenta to the pulmonary arteries in the fetal circulation. In the vast majority of newborns, the ductus closes by 1 month of age. However, a persistently patent ductus arteriosus (PDA) can occur (estimated at approximately 3/10,000 live births). With the rapid decline of pulmonary vascular resistance after birth, flow across the PDA is directed “left-to-right” from the aorta to the pulmonary arteries. If the PDA persists into adulthood, it results in overcirculation of blood through the pulmonary arteries, the pulmonary veins, the left atrium (LA), and the left ventricle (LV).
In an adult with a PDA, the findings include:
- 1.
Dilated LA and LV without other etiology
- 2.
Persistent flow across the PDA, which, on echocardiography, is best visualized in the parasternal short-axis image at the base of the heart or suprasternal notch imaging of the descending aorta
- 3.
Right ventricle (RV) hypertension and pulmonary hypertension (as a result of Eisenmenger syndrome)
Diagnosis of a PDA is often made in the parasternal short-axis view with color Doppler evaluation. Imaging should focus on the pulmonary artery bifurcation ( Fig. 45.1 and 
). Flow from a PDA originates near the origin of the left pulmonary artery with continuous flow into the pulmonary artery shown by color Doppler. Usually, the color flow jet is visible, but visualization of the actual ductus is often difficult in adults. Suprasternal imaging of the aortic arch may be used with color Doppler with the imaging plane angulated towards the left pulmonary artery ( 
). Flow from the aorta to the pulmonary artery through the ductus can be visualized in this view.
. Continuous-wave Doppler interrogation of the flow through a PDA with left-to-right shunting will demonstrate continuous flow from the aorta to the pulmonary artery. Flow velocity will vary between systole and diastole, with the higher flow velocities in systole, reflecting the larger pressure gradient. An estimation of the pressure gradient across the ductus can be helpful to determine whether pulmonary hypertension is present. Measurement of the peak velocity during systole (at or just after the R wave on electrocardiogram) reflects the pressure difference between aortic and pulmonary artery systolic pressure. Low velocity flow across a PDA suggests pulmonary hypertension.
Tetralogy of Fallot
Tetralogy of Fallot (TOF) represents one of the largest groups of adults with complex congenital heart disease. Initial palliative surgeries were performed in the 1940s, with ultimate repairs being accomplished by the mid-1950s. As a result, there is a growing cohort of adults with repaired TOF with improving survival but a risk for morbidity.
Imaging Approach to the Adult With Repaired Tetralogy of Fallot
- 1.
Understanding of baseline anatomy:
- a.
Unrepaired: Although uncommon in adulthood, patients can present with TOF without repair. Diagnosis is made by defining the VSD (often termed the conoventricular VSD), overriding aorta, right ventricular outflow tract (RVOT) obstruction, and RV hypertrophy ( Fig. 45.2 ).
FIG. 45.2
Diagram of the native anatomy of tetralogy of Fallot.
From Brickner ME, Hillis LD, Lange RA: Congenital heart disease in adults. Second of two parts. N Engl J Med. 2000;342(5):334–342. Copyright © 2000 Massachusetts Medical Society. Reprinted with permission.
- b.
Initial surgical shunting: Most patients have had palliative shunting that may have included aortopulmonary shunts or subclavian to pulmonary artery shunts. Prior shunt sites can become stenotic or aneurysmal, thus specific evaluation is needed.
- c.
Repair type: While the majority of adult patients had a transannular patch ( Fig. 45.3 ), RVOT patches or RV-pulmonary artery (PA) conduits ( Fig. 45.4 ) have also been used.
FIG. 45.3
Parasternal long axis of a patient with repaired tetralogy of Fallot.
Note the small patch margin defect with left-to-right flow.
FIG. 45.4
Right ventricle-pulmonary atresia (RV-PA) conduit for tetralogy of Fallot.
(A) RV-PA conduit shown in the parasternal long axis angled superiorly. The right image shows turbulent flow in the conduit. (B) The same conduit as in (A) shown on cardiac magnetic resonance imaging in three-dimensional reconstruction.
- d.
Pulmonary artery anatomy: Significant hypoplasia or pulmonary artery atresia can occur, resulting in significantly abnormal PA development and function
- e.
Aortic arch sidedness: Approximately 10% to 25% of TOF patients have right aortic arches.
- a.
- 2.
Evaluation of right atrium (RA) and RV: RA and RV size should be near normal in a patient with a good repair and no residual or recurrent lesions. A dilated RV suggests the presence of significant pulmonary regurgitation, tricuspid regurgitation (TR), or both. A hypertrophied RV suggests the presence of residual or recurrent RV outflow obstruction. Residual dilation and hypertrophy also can be secondary to significant delay in repair.
- 3.
Repair integrity/results:
- a.
Ventricular septal patch: Evaluation for residual defects or aneurysm. Color Doppler interrogation should be performed in multiple views with the color box encompassing the patch. Most residual defects occur at the margin of the patch.
- b.
RVOT/pulmonary valve function: By using two-dimensional (2D) imaging, color and spectral Doppler evaluation for obstruction should be performed at the level of the infundibulum, pulmonary valve, main or branch PAs. Some patients will have a valved RV-to-PA conduit or pulmonary homograft. The origin of RV-to-PA conduits may require off-axis imaging to identify the origin of the conduit and to appropriately align the Doppler cursor to interrogate the valve/conduit (see Fig. 45.4 ).
- a.
- 4.
Left ventricular systolic and diastolic function
- 5.
Aortic root dilation: The aortic root is frequently dilated in patients with TOF, and can be associated with aortic valve regurgitation. Aortic regurgitant jets are frequently angled towards the VSD patch, and it is important to visualize/assess the jet origin.
Key Imaging Views
In addition to the standard adult protocol, TOF imaging should include:
- 1.
Evaluation for residual VSD-parasternal long-axis view
- 2.
Pulmonary valve function and evaluation for pulmonary artery stenoses with pulsed Doppler along the RVOT to branch PAs, continuous Doppler across the RVOT for pulmonary regurgitation and stenosis evaluation (parasternal short axis, long axis).
- a.
For patients with a history of significant pulmonary stenosis or pulmonary atresia, extended views can be performed in the parasternal short-axis orientation. By shifting the imaging probe slightly towards the diaphragm and angling superiorly, the branch pulmonary arteries may come into view. Additionally, anastomotic sites of the RV-PA conduit should be imaged.
- a.
Transposition of the Great Arteries
Transposition of the great arteries (TGA) has two predominant types. The most common type is often referred to as D-loop TGA. The less common form is called physiologically or congenitally corrected transposition (also known as L-loop TGA). Embryologically, as the heart is forming, the heart tube makes a rightward loop (i.e., a D-loop). In patients with D-Loop TGA, their ventricles are in the typical location. If the heart loops incorrectly, it has an L-loop and the ventricles have an inverted relationship.
In D-loop TGA, the great arteries are transposed so the aorta is located anterior and rightward to the pulmonary artery. The aorta is associated with the RV and the pulmonary artery to the LV. As this circulation is not physiologically sustainable, an initial palliative procedure must be done to increase arterial and venous mixing until the ultimate repair is completed (e.g., balloon atrial septostomy). Based on era and location of birth, the final procedure to restore systemic venous blood circulation to the pulmonary artery and pulmonary venous blood to the aorta was either an atrial switch or an arterial switch ( Fig. 45.5 ).
- 1.
Atrial switch: Fundamentally, in this procedure, systemic venous blood is re-routed (baffled) directly to the LV to ultimately go to the pulmonary artery. The pulmonary venous blood is then baffled to the RV and on to the aorta. At least one patch is made in the coronal plane to septate the atria anterior-to-posterior rather than right-to-left.
- a.
Imaging approach:
- i.
The ventricles: The ventricles in the atrial switch patients can be best visualized in the apical four-chamber and the parasternal short-axis view. In the apical four-chamber view, the RV appears enlarged and hypertrophied while the LV (subpulmonary ventricle) appears small. In short-axis views, the anterior RV (which generates systemic pressure) flattens the posteriorly positioned LV (which pumps to the pulmonary artery). Assessment of the systemic RV (both systolic and diastolic function) and the systemic AV valve (tricuspid valve) is important, since a significant number of these patients develop heart failure with systemic (RV) ventricular dysfunction and TR.
- ii.
Systemic and pulmonary venous baffles: superior vena cava (SVC) and IVC blood are redirected to the mitral valve and subpulmonic LV. Pulmonary vein flow is directed around the systemic venous baffle to the tricuspid valve and the systemic RV. In the apical four-chamber view, a portion of the baffle system can be easily seen in the LA, bisecting the LA. The portion of the LA closest to the mitral valve receives inflow from the SVC and IVC limbs. Pulmonary venous return to the posterior portion of the atrium flows across the pulmonary venous channel (where the atrial septum has been resected) into the RA. Flow across the pulmonary vein channel should be low velocity (unobstructed). The areas of baffle anastomosis and along the contour of the baffle can become stenosed, aneurysmal, and/or develop leaks. Thus careful evaluation of the baffle with both 2D imaging, low Nyquist/high-frame-rate color Doppler and pulsed-wave Doppler is important ( Fig. 45.6 ). Screening for baffle leaks can be done with agitated saline contrast ( Fig. 45.7A shows a normal baffle, and Fig. 45.7B shows a baffle leak). See also
.
- i.
- a.
