Conotruncal Lesions

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7 Conotruncal Lesions

Amy H. Schultz

Tetralogy of Fallot

Background

• The four historically described features of tetralogy of Fallot (TOF) are ventricular septal defect (VSD), overriding aorta (Ao), pulmonary stenosis (PS), and right ventricular hypertrophy (RVH) (Fig. 7-1).
• However, it is better for the echocardiographer to understand the key features:

• Large VSD of the anterior malalignment type (the conal or infundibular portion of the ventricular septum [VS] is anteriorly displaced).
• Underdevelopment of the right ventricular outflow (RVO), which can lead to obstruction at the subvalvar, valvar, and supravalvar levels.
• The aortic override and RVH can be thought of as secondary consequences to these features.

• A continuum of severity exists.

• “Pink tets” have little in the way of PS, exclusively left-to-right shunting and physiology more akin to a large VSD.
• The typical patient with TOF has an intermediate degree of obstruction, which usually progresses with time.
• Toward the severe end of the spectrum, there may be critical degrees of obstruction, requiring ductal patency for adequate oxygenation.
• In the extreme, there is pulmonary atresia. There may be no identifiable central pulmonary arteries (PAs); the lungs are supplied by multiple collateral vessels, termed major aortopulmonary collaterals (MAPCAs). This anatomy is also termed pulmonary atresia/VSD, distinguishing it from pulmonary atresia with an intact VS.

• A notable variant is TOF with absent pulmonary valve (pulmV) syndrome.

• The pulmonary valve leaflets are vestigial. In utero, there is free pulmonary insufficiency (PI) and usually a relatively mild degree of stenosis.
• The ductus arteriosus is usually absent.
• The branch PAs are often severely dilated and may compress the airways, leading to severe respiratory distress at birth.
• A typical TOF repair involves closing the VSD to provide unobstructed outflow from the left ventricle (LV) to the aorta and relief of all levels of pulmonary valve stenosis, often using a transannular patch.
• Coronary artery anatomy must be clearly defined before placement of a transannular patch to ensure that no important coronary artery crosses the right ventricular outflow tract (RVOT).

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Figure 7-1 Schematic depicting the anatomy of tetralogy of Fallot (TOF).

Overview of Echocardiographic Approach

• Cardiac segmental connections are normal (two dimensional [2D]).
• Demonstrate the anterior malalignment of the conal septum and the various levels of RVOT obstruction (2D, color Doppler, pulsed wave [PW] Doppler, and continuous wave [CW] Doppler).
• Demonstrate the branch PAs (or lack thereof if not present) (2D, color Doppler).
• Evaluate for DA (2D, color Doppler, PW Doppler, CW Doppler).
• Evaluate for additional VSDs (2D, color Doppler).
• Evaluate coronary artery anatomy (2D, color Doppler).
• Evaluate arch branching pattern; right aortic arch is present in approximately 25% (2D, color Doppler).

Anatomic Imaging

Acquisition

• Transthoracic echocardiography (TTE) is used to establish the diagnosis in neonates.
• Transesophageal echocardiography (TEE) may be used pre- and postoperatively.
• Beginning with the subcostal views, evaluate the segmental anatomy.

• Perform careful 2D sweeps in the frontal (long axis) and bicaval (sagittal) planes, noting the morphology and relationship of structures. The segmental anatomy is normal (see Chapter 1, The Pediatric Transthoracic Echocardiogram).
• In addition, perform a true subcostal short axis (45 degrees between the frontal and bicaval planes) 2D sweep from base to apex. This can be particularly helpful in visualizing:

• Atrial septal defect (ASD).
• Ventricular morphology.
• Malalignment VSD (the anterior malalignment of the conal septum is well seen).
• Any additional muscular VSDs.
• Mitral-aortic fibrous continuity (if no continuity, consider the diagnosis of double-outlet right ventricle [DORV]).
• RVOT.

• A right oblique view can be obtained by rotating 90 degrees counterclockwise from the short axis view and angling the beam of sound toward the right shoulder. This provides good views of the anterior malalignment VSD and RVOT (Fig. 7-2).

• Apical views

• Ensure that both ventricles have normal size and function.
• In the five-chamber view, the main VSD is apparent.
• Assess for any additional muscular VSDs.

• Parasternal long axis view (Fig. 7-3)

• Note mitral-aortic fibrous continuity. If not present, consider the diagnosis of DORV.
• Note the override of the aortic valve (AV).
• Optimize image of pulmonary valve for annular measurement.
• Parasternal short axis view (Fig. 7-4)

• Note the anterior malalignment of the conal septum and the large VSD.
• Note any evidence of RVOTO, pulmonary valve hypoplasia/stenosis, supravalvar stenosis, and branch PA stenosis.

• In TOF/absent valve, the main PA and branch PAs will be dilated (Fig. 7-5).
• In TOF with pulmonary atresia, the main PA (Fig. 7-6) or central PAs may be absent.

• Carefully image the coronary arteries (Figs. 7-7 and 7-8). In particular, demonstrate the origin and course of the anterior descending coronary and rule out any coronary artery crossing the pulmonary outflow tract. A significant coronary artery crossing the pulmonary outflow tract precludes a transannular patch. Decreasing the dynamic range and appropriate adjustment of focal zone and zoom features facilitates visualization.
• Short axis sweeps of the ventricles are used to evaluate function and any additional VSDs. Additional muscular VSDs may be difficult to detect by color Doppler imaging in the presence of another large VSD; thus, careful attention to the 2D images is mandatory.
• High parasternal short axis images, rotated slightly counterclockwise, may be used to image a patent ductus arteriosus (PDA).
• Suprasternal notch imaging

• Demonstrate arch sidedness and branching from the suprasternal short axis view. A right aortic arch occurs in about 25%. Some types of right aortic arch constitute a vascular ring. (See Chapter 1, The Pediatric Transthoracic Echocardiogram, for technique.)
• Branch PAs may be well seen from suprasternal notch short axis view.
• With variants of TOF with more significant obstruction, the ductus may be tortuous and originate from the underside of the arch. This is best seen with the sagittal view of the arch.

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Figure 7-2 Subcostal right oblique views of the right ventricular outflow tract (RVOT) in TOF. A, Two-dimensional (2D) image shows the anteriorly malaligned conal septum and the resultant VSD. The RVOT is somewhat narrowed by the deviated conal septum.B, The addition of color Doppler shows aliasing of flow in the RVOT. C, Pulsed wave Doppler in the RVOT shows only mild acceleration of flow in the RVOT. There is a slightly late-peaking waveform, consistent with dynamic obstruction. In this patient, the obstruction was predominantly higher up, at the valve level.

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Figure 7-3 Parasternal long axis view of unrepaired TOF: the aorta (Ao) is seen overriding the ventricular septal defect (VSD); fibrous continuity between the aortic valve (AV) and mitral valve (MV) is noted.

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Figure 7-4 Parasternal short axis view of unrepaired TOF: the anteriorly malaligned conal septum is well seen, leaving a large VSD. The RVOT is narrowed, and the pulmonary valve (pulmV) is hypoplastic. A restricted jet of color flow passes through the pulmonary valve, which in this case was unicuspid.

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Figure 7-5 Parasternal short axis view of the pulmonary valve and proximal PAs in TOF with absent pulmonary valve syndrome. The hypoplastic pulmonary valve annulus with vestigial pulmonary valve leaflets is seen. The proximal right pulmonary artery (RPA) is massively dilated; the origin of the dilated left pulmonary artery (LPA) is seen.

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Figure 7-6 Parasternal short axis view of the PAs in TOF with pulmonary atresia. In this case, the central PAs are confluent, but there is no main PA segment. The color panel shows the entry of the ductus (red) into the confluence of the branches.

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Figure 7-7 Parasternal short axis 2D image showing a normal course of the left anterior descending coronary artery. In this case (not shown), the right coronary artery was also shown to be normal, with no significant branch crossing the RVOT. Color confirmation of the coronary courses is also recommended (not shown).

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Figure 7-8 Coronary artery patterns observed in TOF. Frequency of occurrence is shown in the lower left-hand corner of each box. Note that approximately 94% of cases of TOF have one of the two “normal” patterns. Although more complex patterns are rare, they are critical to recognize because they preclude indiscriminate transannular patch. Conduit placement or careful, limited transannular incisions are required for repair.

(From Need LR, et al. Coronary echocardiography in tetralogy of Fallot: diagnostic accuracy, resource utilization and surgical implications over 13 years. J Am Coll Cardiol. 2000;36:1371–1377.)

Analysis

• Measure ASD/patent foramen ovale (PFO) from the subcostal 2D views.
• Measure the malalignment VSD from the parasternal short axis 2D view and another orthogonal view (apical or subcostal).
• Measure any additional VSD in the view in which it is best seen.
• Measure the pulmonary valve annulus, main PA, and branch PAs from the parasternal views. Compare with norms based on body surface area (BSA) (Z scores).
• Measure the PDA at its narrowest point in the view in which it is best seen.

Pitfalls

• In TOF with pulmonary atresia with no central PAs, the left atrial appendage (LAA) can be mistaken for the main PA. Avoid this pitfall by careful attention to the 2D images and use of color Doppler. The LAA will have a to-and-fro flow pattern in it.

Physiologic Data

• Doppler techniques are used to:

• Assess size, location, and direction of shunting of ASDs and VSDs.
• Evaluate PDA.
• Assess RVOTO and PA stenosis.
• Further visualize coronary arteries.

• Subcostal views

• Perform color sweeps of the atrial septum (AS) and VS. Be alert for any additional muscular VSDs, which may be difficult to visualize because the ventricular pressures are typically equal due to the large primary VSD. Determine the direction and velocity of shunting across shunts. Generally, VSDs will be unrestrictive.
• Evaluate RVOT from the subcostal short axis view.

• This view provides good Doppler alignment for spectral analysis in the subvalvar and valvar region.
• Perform a careful PW analysis, starting within the right ventricle (RV) below any muscle bundles evident on 2D imaging, marching up through the RVOT and pulmonary valve. Use the 2D image to guide your placement of the Doppler cursor, thus demonstrating the significance of obstruction at the various levels.
• Use CW Doppler to determine the highest velocity.

• Apical views

• Assess tricuspid valve (TV) and mitral valve (MV) function with color Doppler. Note that obtaining a right ventricular (RV) pressure estimate is irrelevant in the presence of a large VSD. The RV pressure is equal to the left ventricular (LV) pressure.
• Evaluate the apical muscular septum with color Doppler for additional VSDs.

• Parasternal views

• Assess valve function with color Doppler.
• Assess outflow tract obstruction with color Doppler and spectral Doppler. In particular, pulmonary outflow obstruction may be assessed from the parasternal short axis. Use careful PW Doppler to localize various levels of obstruction. Use CW Doppler to assess highest velocity.
• Evaluate the muscular septum with color Doppler for additional VSDs.
• Use color Doppler with very low Nyquist limit to assess flow in coronary arteries. Confirm that direction of flow is consistent with your understanding of the 2D anatomy. If not, reevaluate 2D anatomy.
• Evaluate for PDA with color Doppler from high parasternal window as described previously. If present, demonstrate velocity and direction of shunting by spectral Doppler.

• Suprasternal sagittal views

• Evaluate for PDA by color Doppler. If a ductus is present, demonstrate velocity and direction of shunting by spectral Doppler.
• In TOF with pulmonary atresia, examine the course of the arch and thoracic aorta with color Doppler to identify collaterals.

Alternate Approaches

• Cardiac catheterization with angiography is used:

• To definitively determine coronary artery anatomy if there is concern about an abnormal pattern or if the coronary arteries were inadequately imaged.
• In all cases of TOF with pulmonary atresia with MAPCAs to determine the number, size, and location of collaterals and to define which segment(s) of the lung is perfused by each collateral.

Key Points

• Key anatomic features

• Large VSD of the anterior malalignment type.
• Underdevelopment of the pulmonary outflow, which can lead to obstruction at the subvalvar, valvar, and supravalvar levels.
• The aortic override and RVH can be thought of as secondary consequences to these features.

• Key aspects of the preoperative echocardiogram

• Define the location and severity of the levels of pulmonary outflow obstruction.
• Evaluate for any coronary artery crossing the RVOT (present in ~5% of cases) that would preclude a transannular patch repair.
• Evaluate for additional VSD and PDA.
• Evaluate arch sidedness and branching pattern.

• Notable anatomic variants include the following:

• TOF with pulmonary atresia (also known as pulmonary atresia/VSD). In the most severe cases, there may be no identifiable central PAs, and the lung fields are supplied by MAPCAs.
• TOF with absent pulmonary valve: main PA and branch PAs are typically severely dilated and may cause airway compression; the ductus is usually absent.

TOF Repaired

Background

• Repair of TOF entails the following:

• Patch closure of the VSD.
• Establishment of unobstructed outflow from the RV to the PAs, tailored to the anatomy of the individual patient.

• In the best case, the pulmonary valve annulus is of adequate size and RV muscle bundles can be resected through the TV and pulmonary valve, avoiding right ventriculotomy (transatrial/transpulmonary repair).
• More frequently, the pulmonary valve annulus is hypoplastic, and a transannular patch is required. The surgeon incises from the main PA, across the pulmonary valve and onto the RV and then augments the area with a patch. Free PI results.
• If a coronary artery crosses the RVOT or if there is pulmonary atresia with no continuity of the main PA to the RV, then an RV-to-PA conduit is placed.
• If pulmonary blood flow (PBF) is via MAPCAs, the collaterals must first be brought together (unifocalized) before the conduit is placed. In this case, often the VSD is not closed at the first operation.

• Closure of any large ASD. A PFO is frequently left open to facilitate maintenance of cardiac output in the immediate postoperative period.

• The most important long-term follow-up issue in TOF is the development of RV dilation and dysfunction due to chronic PI and previous ventriculotomy. Serial evaluation of RV size and function is key.
• Branch PA stenosis can be an important issue after TOF repair.
• Aortic root enlargement and aortic insufficiency are observed late after TOF repair.

Overview of Echocardiographic Approach

• Review the history if possible before beginning the study to understand what type of repair was performed.
• Evaluate for residual ASD or VSD (2D, color Doppler, PW Doppler, CW Doppler).
• Evaluate the outflow from the RV to PAs (2D, color Doppler, PW Doppler, CW Doppler).

• Residual obstruction can occur at any level. Use PW Doppler to localize any area of obstruction.
• Free PI is often present (color Doppler, PW Doppler).
• Evaluate for branch PA stenosis (more commonly left).

• Evaluate RV size and function (2D). Estimate RV pressure if possible from the TR velocity (color Doppler, PW Doppler, and CW Doppler).
• Evaluate aortic root size and AV regurgitation (2D, color Doppler).

Anatomic Imaging

Acquisition

• Subcostal views

• Perform 2D sweeps to evaluate for obvious residual ASD or VSD. Use the short axis subcostal view to visualize the RVOT.

• Apical views

• Assess the size and function of both ventricles, in particular the RV.

• TOF repair often leads to long-standing severe PI, which can lead to right heart dilation and RV dysfunction.
• Previous ventriculotomy also contributes to RV dysfunction.
• As the right heart dilates, the angle of the TV annulus may tilt, the RV develops a “shoulder” near the free wall TV annulus, and the apex becomes broader (Fig. 7-9).
• Assessment of RV dilation remains a qualitative assessment.

• Visualize the VSD patch from the five-chamber (5C) view, assess for any obvious residual VSD.

• Parasternal views

• Optimize long axis 2D image for measurement of aortic annulus, root, sinotubular junction, and ascending aorta.
• The VSD patch can be visualized from long axis and short axis views; assess for any obvious residual VSD.
• Visualize the RVOT and branch PAs. Optimize view of branch PAs for measurement. If a conduit is present, pay attention to the motion of the conduit valve leaflets, which can become calcified and immobile over time.
• Assess the size and function of both ventricles.

• The RVOT in particular may demonstrate hypokinesis due to a history of ventriculotomy and the presence of a transannular patch.
• Compare the size of the RV with that of the LV in the short axis view (Fig. 7-10).
• Note whether RVH is present.

• Septal wall motion is often paradoxical after TOF repair. This finding is not concerning in and of itself. It may render shortening fraction an inaccurate assessment of LV systolic function.

• Suprasternal notch views: may be used to visualize branch PAs if not well seen from the parasternal short axis view.
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Figure 7-9 Apical view of a dilated right ventricle (RV) after repair of TOF. Note the broad right ventricular apex, the “shoulder” of the RV cavity near the lateral tricuspid annulus, and the tilt of the tricuspid valve (TV) annular plane relative to the plane of the MV.

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Figure 7-10 Parasternal short axis view of the RV and left ventricle (LV) after repair of TOF in a patient with severe RV dilation.

Analysis

• Measure the size of any residual ASD or VSD from the 2D views where best visualized.
• In the apical view, assess TV annulus angle. An angle greater than 20 degrees has been associated with RV volume greater than 150 mL/m2 (Fig. 7-11).
• Assess biplane LV ejection fraction in the apical view.
• Measure LV dimensions in the parasternal short axis or long axis view. Calculate shortening fraction if septal wall motion is not paradoxical.
• Measure branch PAs from the parasternal short axis view or the suprasternal notch view. Compare with norms for BSA (Z score) in smaller patients. Usual norms can be used for average adult-sized patients.
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Figure 7-11 Method for calculating TV annular tilt for assessment of RV dilation.

(From Punn R, Behzadian F, Tacy TA. Annular tilt as a screening test for right ventricular enlargement in patients with tetralogy of Fallot. J Am Soc Echocardiogr. 2010;23(12):1297–1302.)

Physiologic Data

• Doppler techniques are used to assess the following:

• Size, location, and direction of shunting of residual ASD and VSD.
• Atrioventricular valve (AVV) function.
• RVO and PAs for residual obstruction.
• Degree of PI.
• AV function.

Acquisition

• Subcostal views

• Perform color Doppler sweeps to identify any residual ASD or VSD. If present, assess direction of shunting. Assess velocity of shunting across any residual VSD.
• Use the subcostal short axis view to assess the RVOT for residual obstruction. Use color Doppler to screen for areas of aliasing and PW Doppler to localize and determine magnitude of obstruction. Obtain overall peak velocity by CW Doppler.

• Apical views

• Assess MV and TV function. Obtain RV pressure estimate if possible.
• Some authors have used RV myocardial performance index as an index of RV function.
• Assess AV function and quantify regurgitation as appropriate.
• Use color Doppler over the VSD patch to assess for any residual defect.

• Parasternal views

• Assess AV regurgitation.
• Assess AVV regurgitation; obtain RV pressure estimate if possible.
• Assess for residual VSD or additional VSD by color Doppler; obtain peak velocity if present.
• Assess RV outflow from the ventricle through the branch PAs for residual obstruction and assess degree of PI (Fig. 7-12).

• Screen for aliasing and flow reversal by color Doppler.
• Note width of PI jet compared with width of RVOT.
• Use PW Doppler at all levels to localize and quantify obstruction. Also note location of flow reversal (main PA, branch PAs).
• Note that multiple levels or long segment narrowing in the pathway from the RV to the PAs may be present. In this case, the mean gradient may be more predictive of true peak-to-peak gradient measured invasively.

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Figure 7-12 Parasternal short axis view with color Doppler of the main and branch PAs in TOF after repair with a transannular patch. This frame is in diastole. Note the reversal of flow (red) all the way to the branch PAs.

Alternate Approaches

• Magnetic resonance imaging (MRI) can quantify RV size and systolic function and the pulmonary regurgitant fraction. In addition, anatomic assessment is superior in patients with poor windows.
• Cardiac catheterization is used to accurately measure pressure gradients, particularly in the setting of multiple levels of obstruction. Filling pressures can also be obtained, and angiography can further clarify anatomy. Interventions are possible for branch PA stenosis, and in some select cases for pulmonary valve replacement.
• Nuclear medicine lung perfusion scan can be performed to quantify relative flow to the two lungs to help determine whether cardiac catheterization for branch PA interventions is indicated.

Key Points

• Repair entails relief of any obstruction to pulmonary outflow (subvalvar, valvar, or supravalvar levels) and patch closure of the VSD. Frequently, a small PFO is left intentionally.
• Frequently, a transannular patch is performed, resulting in free PI.
• Important postoperative features to evaluate include the following:

• Residual VSD or ASD.
• Residual pulmonary outflow obstruction at any level.
• Branch PA stenosis.

• The most common long-term follow-up issue is RV dilation and dysfunction in the setting of free PI.
• If a conduit is used in the repair, it should be assessed for both insufficiency and stenosis.

Double-Outlet Right Ventricle

Background

• The diagnosis of DORV is a “grab bag” of lesions that share the common feature that both the aorta and PA arise from the RV.
• It can be difficult to determine when the aorta is “assigned to” the RV.

• If the aorta is normally located, but the portion of the VS beneath it is missing, the aorta will appear to override the VS.
• Most forms of DORV include a VSD.

• Features that suggest (controversy exists here) that the aorta should be “assigned to” the RV include the following:

• Separation of the aortic annulus from the mitral annulus by muscle.
• The aorta lies more than 50% over the RV.

• Observing the location of the VSD and the relationship of the great vessels (GVs) to each other and the VSD is key.
• It is useful to subcategorize DORV into several recognizable types to aid recognition and management. Traditionally, this has been done based on the relationship of the VSD to the GVs (Fig. 7-13).

• DORV with subaortic VSD and

• No pulmonary stenosis (VSD type).
• Pulmonary stenosis (tetralogy type).

• DORV with subpulmonary VSD (transposition type).

• The form of DORV with subpulmonary VSD, side-by-side GVs, and bilateral conus is given the eponym Taussig-Bing anomaly.

• DORV with doubly committed VSD: in this anatomy, the VSD is very large, often due to hypoplasia or absence of the conal septum. Both GVs are related to the VSD. Typical repair is similar to that for the VSD type.
• DORV with remote or noncommitted VSD and other more complex forms of DORV need to be managed on an individual basis and are often treated with single-ventricle (SV) palliation.
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Figure 7-13 Schematic showing the physiology of three major types of double-outlet right ventricle (DORV). A, DORV with subaortic VSD and no pulmonary stenosis (PS) (VSD type): oxygenated left ventricular (LV) blood (open arrow) is directed through the VSD to the aorta; deoxygenated RV blood (solid arrow) is directed to the PA. B, DORV with subaortic VSD and PS (tetralogy type): oxygenated LV blood (open arrow) is directed through the VSD to the aorta; due to the presence of PS, deoxygenated RV blood (solid arrow) flows partly to the PA and partly across the VSD to the aorta. C, DORV with subpulmonary VSD (transposition type): oxygenated LV blood (open arrow) is directed preferentially through the VSD to the PA; deoxygenated RV blood (solid arrow) is directed preferentially to the aorta.

(Redrawn from Silka MJ. Double outlet right ventricle. In McMillan JA, DeAngelis CD, Feigin RD, Warshaw JB, eds. Oski’s Pediatrics: Principles and Practice, 3rd ed. Philadelphia: Lippincott Williams & Wilkins, 1999, Figure 3-11.)

Overview of Echocardiographic Approach

• A segmental approach to assessing the anatomy is used (2D) to:

• Establish normal atrial situs.
• Evaluate ventricular looping: normal for the noncomplex varieties; complex forms of DORV are not further discussed here.
• Evaluate GVs.

• Commitment to the LV versus RV.
• Relationship to each other and the VSD.
• Note any obstruction to either GV (subvalvar or valvar level).

• Subcostal views are the best for determining the degree of commitment of each GV to the LV versus RV and for visualizing the pathway from the LV to the most proximal GV.
• Parasternal long axis view: useful for identifying a lack of fibrous continuity between the MV and the closest GV.
• Be alert for complicating features such as straddling AVVs.
• Color Doppler and spectral Doppler are used to assess outflow tract obstruction.

Anatomic Imaging

Acquisition

• TTE is used to establish the diagnosis in neonates.
• TEE may be used pre- and postoperatively and may be performed specifically to assess the relationship of the VSD to the GVs.
• Three-dimensional (3D) imaging can be important in helping to understand the size of the VSD and its relationship to the GVs, particularly in cases in which there is concern about the adequacy of the pathway of the LV to the nearest GV.
• As discussed previously, DORV is a “grab bag” of many different lesions. The following discussion applies to the more straightforward forms, characterized by fundamentally normal atrial situs and ventricular looping with various relationships of the GVs to each other and the VSD. There are many more complex hearts that fall under the moniker of DORV but are beyond the scope of this chapter.
• Beginning from the subcostal views, evaluate the segmental anatomy.

• Perform careful 2D sweeps in the frontal (long axis) and bicaval (sagittal) planes, noting the morphology and relationship of structures.
• In addition, perform a true subcostal short axis (45 degrees between the frontal and bicaval planes) 2D sweep from base to apex. This can be particularly helpful in visualizing ventricular morphology, commitment of the GVs, the VSD, and the potential pathway from the LV to the nearest GV (Fig. 7-14).
• Atrial situs solitus: the inferior vena cava (IVC) enters the right atrium (RA); at least some pulmonary veins (PVs) enter the left atrium (LA). Note any ASD or PFO.
• Ventricular looping: D-looped (normal) in the subset of DORV discussed here:

• The morphologic RV is on the right, characterized by coarse trabeculations and a morphologic TV with chordal attachments to the septum.
• The morphologic LV is on the left, characterized by a smooth septal surface and a morphologic MV with no chordal attachments to the septum.

• GV relationships: identify each GV; note the GV relationships to each other and the commitment to each ventricle.

• The PA is identified as the GV that bifurcates; the aorta does not bifurcate and has coronary arteries arising from it.
• In the long axis view, note whether there is separation of the MV from the closest GV.
• In the true short axis view, note the degree of commitment (location over) of each GV, the LV and RV; more than 50% override above the RV suggests commitment to the RV.
• Note the relationship of the GVs to each other: usual spiral relationship with the aorta posterior and to the right is seen in the VSD type and tetralogy types. Parallel relationship with the aorta rightward is seen in the transposition type (see Chapter 8, Transposition of the Great Arteries, for further discussion of imaging).

• Once the segmental anatomy is established, use the subcostal views to further define additional details of the anatomy.

• Note the relationship of the VSD to the GVs. Optimize images of the potential pathway from the LV to the nearest GV.
• If the VSD is subaortic, examine for evidence of subvalvar or valvar PS to distinguish between the VSD type and the tetralogy type. The subcostal short axis view is particularly good for evaluation of subpulmonary stenosis.
• If the VSD is subpulmonary and the GVs are transposed, evaluate for evidence of subvalvar or valvar AS. If present, be alert for evidence of arch obstruction on later views.
• Be alert for any evidence of straddling AVVs (chordae or leaflets crossing the VSD to attach into the other ventricle).
• In the transposition type, note the size of the atrial shunt. Although a large VSD is invariably present, an atrial communication may also be needed for effective mixing as streaming from the LV to PA and RV to aorta can occur (see Chapter 8, Transposition of the Great Arteries, for further details).

• Apical views

• Ensure that both ventricles are apex forming.
• Examine for any evidence of straddling AVVs.
• With anterior angulation, evaluation of the outflow tracts is possible.
• Assess for any additional muscular VSDs.

• Parasternal long axis view (Fig. 7-15)

• Note muscular separation of the MV from the nearest GV.
• Visualize potential pathway from the LV to the nearest GV.
• Parasternal short axis view

• Note the relative positions of the semilunar valves and reconfirm the relationship of the GVs. Evaluate the morphology of the semilunar valves.
• In the VSD type, the GVs have a usual relationship to one another, with the AV seen in cross section and the pulmonary valve and main PA in the long axis view wrapping around the AV.
• In the tetralogy type, the relationship of the GVs to each other is usual (as above in VSD type), but the conal septum will be noted to be anteriorly malaligned in the parasternal short axis view.

• Note any evidence of RVOTO, pulmonary valve hypoplasia/stenosis, and PA stenosis.
• Carefully image the coronary arteries. In particular, demonstrate the origin and course of the anterior descending coronary and rule out any coronary crossing the pulmonary outflow tract. A significant coronary crossing the pulmonary outflow tract precludes a transannular patch. Decreasing the dynamic range and appropriate adjustment of focal zone and zoom features facilitates visualization.

• In the transposition type, the semilunar valves are usually side by side, AV rightward, but the AV may also be anterior and rightward.

• Delineation of coronary artery anatomy is key (see Chapter 8, Transposition of the Great Arteries, for details) because management may be by arterial switch operation (ASO).
• The more side by side the GVs are, the greater the risk of a so-called inverted coronary artery pattern, where the right coronary artery arises from a more leftward sinus and then crosses anteriorly to the native AV. This is of concern if a transannular patch will be needed after ASO to alleviate neopulmonary outflow obstruction.
• Cranial angulation demonstrates the branch PAs arising from the pulmonary valve.

• Short axis sweeps of the ventricles are used to evaluate function and any additional VSDs. Additional muscular VSDs may be difficult to detect by color Doppler imaging in the presence of another large VSD; thus, careful attention to the 2D images is mandatory.
• High parasternal short axis images, rotated slightly counterclockwise, may be helpful in imaging a PDA in the VSD or tetralogy types; the ductus will likely be seen better from the sagittal view of the arch in the transposition type.

• Suprasternal notch imaging

• Arch sidedness and branching should be established from the suprasternal short axis view due to the significant association between the DORV and right aortic arch. Some types of right aortic arch constitute a vascular ring (see Chapter 1, The Pediatric Transthoracic Echocardiogram, for technique).
• The transposition type has a significant association with arch obstruction (particularly if subaortic or AV stenosis is noted). Evaluate the arch carefully by 2D imaging. It may be difficult to rule out a coarctation if a large PDA is present.
• In the transposition type, the PDA is usually best imaged in the sagittal (long axis) view of the arch. In the tetralogy type with more significant obstruction, the PDA may be seen as a tortuous vessel arising from the underside of the arch in this view.

image

Figure 7-14 Subcostal short axis view of a DORV with a subaortic VSD. The aorta appears to sit completely over the RV. There is no mitral-aortic continuity (the MV is not even apparent in this view). The pathway from the LV through the VSD to the aorta is shown. Chordal attachments to the ventricular septum (VS) are noted on the RV side, consistent with RV morphology.

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Figure 7-15 Parasternal long axis view of a DORV. In this case (which has a subaortic VSD), the MV is well seen, but the AV is not even visible due to its displacement over the RV. The large VSD is well seen.

Analysis

• Key measurements include the size of the ASD, VSD, and semilunar valves.
• The ASD is measured from the 2D subcostal images. This is particularly important in the transposition type.
• The VSD is measured from multiple views. Use the subcostal short axis view and the parasternal short axis view in particular. A 3D en face view of the VSD can also be particularly helpful.
• Measure any additional VSD in whichever view it is identified.
• Measure both semilunar valves in systole, typically from the parasternal views. Compare with norms for BSA.

Pitfalls

• The most difficult aspects of imaging a DORV are determining the size of the VSD and determining its relationship to the GVs.
• Use careful subcostal 2D imaging to determine these features. Spend a lot of time on the subcostal views, understanding what you are seeing. Use the subcostal short axis view described above. Do not turn on the color until you understand the 2D anatomy.
• Use 3D imaging of the VSD to further understand its size and shape.

Physiologic Data

• Doppler techniques are used to:

• Assess size, location, and direction of shunting of ASDs and VSDs.
• Evaluate PDA.
• Assess for outflow tract obstruction.
• Further visualize coronary arteries.

• Subcostal views

• Perform color sweeps of the AS and VS. Be alert for any additional muscular VSDs, which may be hard to visualize because the ventricular pressures are typically equal due to the large primary VSD. Determine direction and velocity of shunting across shunts. Generally, VSDs will be unrestrictive.
• Evaluate outflow tracts for evidence of aliasing. Use careful PW Doppler to localize various levels of obstruction. Use CW Doppler to assess highest velocity.

• In the tetralogy type, the pulmonary outflow is well seen from a subcostal short axis, and this provides good Doppler alignment for spectral analysis in the subvalvar and valvar region.

• Apical views

• Assess TV and MV function.
• With anterior angulation, additional color Doppler and spectral Doppler evaluation of the outflow tracts can be performed.
• Evaluate the apical muscular septum with color Doppler for additional VSDs.

• Parasternal views

• Assess valve function with color Doppler.
• Assess outflow tract obstruction with color Doppler and spectral Doppler. In particular, pulmonary outflow obstruction may be assessed in the tetralogy type from the parasternal short axis. Use careful PW Doppler to localize various levels of obstruction. Use CW Doppler to assess highest velocity.
• Evaluate the muscular septum with color Doppler for additional VSDs.
• Use color Doppler with a very low Nyquist limit to assess flow in coronary arteries. Confirm that direction of flow is consistent with your understanding of the 2D anatomy. If not, reevaluate 2D anatomy.
• Evaluate for DA with color Doppler from high parasternal window as described earlier for VSD and tetralogy types. If present, demonstrate velocity and direction of shunting by spectral Doppler.

• Suprasternal sagittal views

• In transposition type, evaluate arch flow pattern by color Doppler and spectral Doppler.
• Evaluate for DA by color Doppler. If a DA is present, demonstrate velocity and direction of shunting by spectral Doppler.

Alternate Approaches

• Cardiac catheterization can be used to define coronary artery anatomy if it is not well seen and delineation is important to the repair (tetralogy or transposition types). MRI may also be used to define anatomic relationships.

Key Points

• DORV is a “grab bag” of lesions that share the common feature that both the aorta and PA arise from the RV.
• Features that suggest that the aorta should be “assigned to” the RV include the following:

• Separation of the aortic annulus from the mitral annulus by muscle.
• The aorta lies more than 50% over the RV.

• Traditionally, the DORV has been subcategorized into several types based on the relationship of the VSD to the GVs.

• DORV with subaortic VSD and no PS (VSD type).
• DORV with subaortic VSD and PS (tetralogy type).
• DORV with subpulmonary VSD (transposition type).
• DORV with doubly committed VSD: typical repair is similar to that for the VSD type.
• DORV with remote or noncommitted VSD and other more complex forms of DORV: managed on an individual basis, often with SV palliation

• Subcostal and parasternal views are most heavily used in assessing the anatomy.

• The pathway from the LV to the nearest GV must be well demonstrated.
• Be alert for complicating features such as straddling AVVs.

• Other aspects of the preoperative assessment are analogous to that of other lesions (VSD, tetralogy type, or transposition type), depending on the anticipated type of repair.

Double-Outlet Right Ventricle: Post-Repair

• The repair of DORV, as described here, is determined by the subtype and analogous to the repairs of the lesion with the same name. The reader is referred to the appropriate sections in this or other chapters.
• In all cases, special attention should be paid in serial follow-up studies to the left ventricular outflow (LVO) pathway because it is at risk of obstruction (early or late).
• For the VSD type of DORV, see Chapter 5, Shunting Lesions.
• For the tetralogy type of DORV, see the section in this chapter on TOF.
• For the transposition type of DORV, ASO with VSD closure is performed; see Chapter 8, Transposition of the Great Arteries. Additional specific issues include the following:

• For ASO with VSD closure in the setting of side-by-side GVs, a LeCompte maneuver may not be performed. Evaluate the course of the branch PAs carefully to determine whether they straddle the ascending aorta.
• There is a much more frequent association with subaortic stenosis, AV stenosis, and arch obstruction in the transposition type of DORV than straightforward dextro-transposition of the great arteries (d-TGA).
• After ASO, aortic outflow obstruction becomes neopulmonary outflow obstruction. Evaluate for this on serial follow-up, or if a transannular patch was performed at any time, evaluate for the secondary consequences of chronic free PI (discussed in the TOF section).
• If subsequent reoperation for neopulmonary outflow obstruction is needed, the coronary artery pattern must be clarified to rule out a crossing coronary artery. One may not be able to determine this by echo in the postoperative state. Review the preoperative comprehensive echocardiogram or use alternate imaging modalities (angiography, computed tomography angiography, or MRI).
• Any aortic arch repair needs to be evaluated serially. There is a particular risk of recoarctation in the first few months after initial repair. See Chapter 12, Left Heart Anomalies, section on coarctation of the aorta.
• More complex forms of DORV are likely to be managed by SV palliation; see Chapter 10, Echocardiographic Imaging of Single-Ventricle Lesions, section on surgical repair.

Truncus Arteriosus

Background

Anatomy

• Truncus arteriosus is a cardiac malformation in which a single semilunar valve and GV emerge from the heart, and the GV gives rise to the aorta and the PAs. The truncal valve typically overrides a large VSD (Fig. 7-16).
• Two classification schemes exist (Fig. 7-17):

• Collett-Edwards types I, II, and III. This classification is more commonly used in clinical practice.

• Type I: an main PA segment is present.
• Type II: the branch PAs arise separately but close to each other from the posterior aspect of the truncus.
• Type III: the branch PAs arise separately from the right and left aspects of the truncus.

• Van Praagh types A1 to A4.
• The truncal valve is frequently abnormal.

• The most common number of cusps is three (69%), with four the next most common (22%), followed by two (9%). One or five is rare.
• 50% of truncal valves have some degree of insufficiency.
• 5% to 10% of truncal valves are stenotic.

• Secundum ASD is reported in 10% to 20% of cases.
• The PDA is absent in at least 50% of cases.
• Interruption of the aortic arch is present in about 15% of cases, typically type B (between the left common carotid and left subclavian arteries).
• The right aortic arch is present in about one third of cases.
• The main anatomic distinctions to be made on the initial echocardiogram are between truncus arteriosus and the following lesions:

• TOF with pulmonary atresia (pulmonary atresia/VSD). Identification of the origin of at least one branch PA from the base of the truncus makes the diagnosis of truncus arteriosus.
• Aortic atresia with VSD and normal-size LV. In this case, the obvious large GV is the PA. A tiny aortic root and ascending aorta can be identified giving rise to the coronary arteries, posterior to the pulmonary root.

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Figure 7-16 Schematic of truncus arteriosus showing a single great vessel (GV) overriding a large VSD. The GV gives rise to the aorta and PAs. Not shown here are the coronary arteries that also arise from the truncal root.

image

Figure 7-17 Two main classification schemes of truncus arteriosus.

(From Momma K. Tetralogy of the Fallot and truncus arteriosus. In: Crawford MH, DiMarco JP, eds. Cardiology. London: Mosby, 2001, Figure 3-12.)

Pathophysiology

• The Qp/Qs (the pulmonary/systemic volume flow rate) is determined by the relative systemic and pulmonary vascular resistance (PVR) and is typically large.
• Low PVR leads to high PBF and a large volume load on the ventricles.
• The ventricular volume load can be aggravated by significant regurgitation of the truncal valve and/or AVVs.
• Coronary perfusion pressure is often low due to low diastolic blood pressure and elevated ventricular end-diastolic pressure.

Overview of Echocardiographic Approach

• A segmental approach to assessing the anatomy is used (2D).

• Establish normal atrial situs.
• Establish normal ventricular looping.
• A single semilunar valve and GV are identified.

• The GV gives rise to the aorta (identify coronaries) and at least one branch PA from the base of the truncus.

• Evaluate the aortic arch carefully.

• It can be easy to mistake a large ductus for the aortic arch in the cases of an interrupted aortic arch.
• Evaluate arch sidedness and branching.

• Evaluate other important aspects of the pathophysiology.

• Truncal valve function.
• AVV function.
• Ventricular function.

Anatomic Imaging

Acquisition

• TTE is used to establish the diagnosis in neonates.
• TEE is used pre- and postoperatively.
• Beginning from the subcostal views, evaluate the segmental anatomy.

• Perform careful 2D sweeps in the frontal (long axis) and bicaval (sagittal) planes, noting the morphology and relationship of structures.
• Atrial situs solitus: the IVC enters the RA, at least some PVs enter the LA. Note any ASD or PFO.
• Ventricular looping: D-looped (normal).

• The morphologic RV is on the right, characterized by coarse trabeculations and a morphologic TV with chordal attachments to the septum.
• The morphologic LV is on the left, characterized by a smooth septal surface and a morphologic MV with no chordal attachments to the septum.
• A VSD is noted underneath the GV.

• A single semilunar valve and GV are identified, overriding the VS.

• Look for evidence of the branch PAs as well as coronary arteries arising from this vessel. The vessel should also continue toward the head as the ascending aorta.

• Apical views

• The four-chamber view appears relatively normal, with perhaps some of the VSD visible.
• With anterior angulation, the truncal valve and truncus become visible, overriding a VSD.
• Assess the apical muscular septum for evidence of additional VSDs.

• Parasternal long axis view

• A single semilunar valve and GV are seen, overriding a large VSD. The degree of override can vary, with some cases predominantly lying over the RV and rarely some predominantly lying over the LV. In most cases, the truncal valve is approximately centered over the VSD.
• Note any thickening or doming of the truncal valve leaflets.

• Parasternal short axis view

• Assess the morphology of the truncal valve. Note the number of cusps and any obvious coaptation gap (Fig. 7-18).
• Identify coronary artery origins from the truncal root. For tips on visualizing coronary arteries, see Chapter 1, The Pediatric Transthoracic Echocardiogram.
• With cephalad angulation, the origins of the branch PAs from the truncus should become apparent (Fig. 7-19). Note whether a main PA segment is present (type I). Optimize 2D image of branch PAs for measurement.
• Evaluate the muscular septum for evidence of additional VSDs.

• Suprasternal notch

• Evaluate arch sidedness and branching from the short axis view. Right aortic arch is seen in about one third of cases (see Chapter 1, The Pediatric Transthoracic Echocardiogram, for technique).
• In the sagittal view, evaluate the aortic arch carefully for evidence of interruption.

• Make sure that you see head and neck vessels emanating from what you think is the aortic arch; it is easy to mistake a large PDA for the transverse arch in cases of truncus arteriosus with an interrupted aortic arch.
• Interruption of the aortic arch in truncus arteriosus typically lies between the left common carotid and left subclavian arteries (type B).

• Also from the sagittal view, evaluate for PDA. The PDA is absent in a large fraction of cases of truncus arteriosus, but not universally so. In truncus arteriosus with an interrupted aortic arch, it is important to evaluate the size and flow pattern of the duct because systemic blood flow to the lower half of the body depends on the duct.

image

Figure 7-18 Parasternal short axis view demonstrating a quadricuspid truncal valve with markedly thickened leaflets. Note the central coaptation gap.

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Figure 7-19 Parasternal short axis view of the truncal root showing the branch PA origins. Note the off-axis angulation, which in this case was necessary to visualize the branch PA origins well.

Analysis

• Measure the size of all shunts at the atrial and ventricular levels.
• Measure the branch PAs and compare to norms (Z scores).
• Measure the PDA, if present, at its narrowest point.

Pitfalls

• When only one GV can be identified, the sonographer may jump to the conclusion that the diagnosis is truncus arteriosus.

• However, to qualify as truncus arteriosus, the GV must give rise to the aorta (marked by coronary arteries) and at least one branch PA.
• In TOF with pulmonary atresia (pulmonary atresia/VSD), the single GV is the aorta (coronaries noted), but the branch PAs do not arise from the base of the truncus.
• In aortic atresia with VSD (and a normal-size LV), the single obvious GV is the main PA, but it does not give rise to the ascending aorta or coronary arteries. Rather, on close inspection, a very diminutive ascending aorta (1–2 mm in diameter) giving rise to the coronaries can be identified.

• It is easy to miss interruption of the aortic arch in truncus arteriosus by mistaking the large PDA for the transverse arch.

• Make sure that you see head and neck vessels emanating from what you think is the aortic arch.

• Do not discontinue prostaglandin until the diagnosis of truncus arteriosus is confirmed, and the aortic arch is determined to not be interrupted.

Physiologic Data

• Doppler techniques are used to:

• Assess size, location, and direction of shunting of ASDs and VSDs.
• Assess truncal valve function.
• Assess arch and, if present, ductal anatomy.

• Subcostal views

• Perform color sweeps of the AS and VS. Be alert for any additional muscular VSDs, which may be hard to visualize as the ventricular pressures are equal due to the large primary VSD. Determine the direction and velocity of shunting across shunts.
• Doppler abdominal aorta. Typically, there is holodiastolic flow reversal due to diastolic flow into the branch PAs. If an interrupted aortic arch is present and there has been constriction of the PDA, poor pulsatility would be seen.

• Apical views

• Evaluate the truncal valve for evidence of stenosis or regurgitation by color Doppler and spectral Doppler. Some flow acceleration is expected due to the large volume load across the truncal valve (Qp + Qs + regurgitant fraction). If the flow acceleration is laminar by PW Doppler and mild in degree, and the valve leaflets appear thin, likely no true stenosis is present.
• Evaluate the MV and TV for evidence of regurgitation.
• Evaluate the apical muscular septum by color Doppler for additional VSD.

• Parasternal views

• Evaluate the truncal valve for regurgitation by color Doppler and examine mechanism.
• Perform a short axis sweep to evaluate the muscular septum by color Doppler for any evidence of additional VSDs.
• Evaluate branch PAs by color Doppler and spectral Doppler in the short axis view. Some flow acceleration is expected, given the typically high Qp.

• Suprasternal notch views

• Evaluate flow in the arch by color Doppler and spectral Doppler.
• If a PDA is present, evaluate flow pattern by color Doppler and spectral Doppler.

Key Points

• A single semilunar valve and GV emerge from the heart and give rise to the aorta and the PAs. The truncal valve typically overrides a large VSD.
• Distinguish truncus arteriosus from:

• TOF with pulmonary atresia.
• Aortic atresia with a VSD and a normal-size LV.

• Evaluate the PA anatomy to subclassify truncus arteriosus.
• The truncal valve is frequently abnormal (50% with some degree of insufficiency, 5%–10% stenotic, 30% with an abnormal number of cusps). Truncal valve stenosis, however, will be overestimated by velocity assessment in the preoperative state when Qp + Qs is traversing the valve.
• Evaluate the aortic arch carefully.

• Interruption of the aortic arch is present in about 15% of cases.
• It can be easy to miss an interruption by confusing the ductal arch for the true aortic arch.

• Other common features include right aortic arch, a secundum ASD, and absence of the PDA (in cases without interruption of the aortic arch).
• In unrepaired truncus arteriosus, the Qp/Qs is typically high, with significant ventricular volume load.

Truncus Arteriosus: Status Post Repair

Background

• Truncus arteriosus is repaired by closing the VSD with a patch such that the LV ejects to the aorta, removal of the PAs from the truncus, and insertion of an RV-to-PA conduit.
• If an interrupted aortic arch is present, the arch is repaired and the ductus is ligated and divided.
• Truncal valvuloplasty may be attempted if the truncal valve is significantly regurgitant. Truncal valve replacement may be required at some point in the patient’s lifetime. Generally, every effort is made to avoid truncal valve replacement in infancy.
• Conduits, especially when inserted in infants, eventually become stenotic and regurgitant.

Overview of Echocardiographic Approach

• Evaluate for residual ASD or VSD (2D, color Doppler, PW Doppler, CW Doppler).
• Right heart issues

• RV-to-PA conduit regurgitation or stenosis (color Doppler, PW Doppler, CW Doppler).
• Branch PA stenosis (color Doppler, PW Doppler, CW Doppler).
• Right ventricular size and function (history of ventriculotomy, volume, and/or pressure load depending on conduit function and branch pulmonary anatomy) (2D).

• Left heart issues

• Left ventricular outflow tract for obstruction, particularly if the truncal valve was very rightward to begin with. Uncommon in straightforward truncus repair (2D, color Doppler, PW Doppler, CW Doppler).
• Truncal (functioning as aortic) valve function (2D, color Doppler, PW Doppler, CW Doppler).
• Left ventricular size and function (especially in the context of truncal valve function) (2D).

Anatomic Imaging

Acquisition

• Subcostal views

• Evaluate for residual ASD or VSD.
• Subcostal short axis imaging can often provide good views of the RV-to-PA conduit.

• Apical views

• Evaluate ventricular function.
• In 5C view, evaluate LVOT and truncal (aortic) valve.

• Parasternal long axis view

• Visualize LVOT, truncal valve leaflets, truncal root, and ascending aorta.
• Evaluate RV and LV function.
• Visualize RV-to-PA conduit.

• Parasternal short axis view

• Assess truncal valve morphology; note the number of cusps and any obvious coaptation gap.
• Assess RV-to-PA conduit and its anastomosis to the branch PAs.
• Pay attention to the motion of the conduit valve leaflets, which can become calcified and immobile over time. Optimize views of branch PAs for measurement of their size.
• Evaluate for residual ASD or VSD.
• Evaluate RV and LV size and function.

• Suprasternal notch

• If there is a history of an interrupted aortic arch, evaluate arch repair (see Chapter 12, Left Heart Anomalies).
• Image the branch PAs from the suprasternal notch short axis view if not well seen from the parasternal short axis view.

Analysis

• Measure any residual ASD or VSD on the 2D images from the views in which it is best seen.
• Measure branch PAs in systole from the parasternal short axis view or suprasternal notch short axis view (compare with norms by Z score).
• Evaluate parameters of LV systolic function. There may be paradoxical septal motion after VSD closure, in which case shortening fraction may not be an accurate assessment of systolic function.
• Measure truncal (aortic) root and the ascending aorta in systole on the parasternal long axis views, which are frequently enlarged. Compare with norms and track over time.

Physiologic Data

• Doppler techniques are used to:

• Assess size, location, and direction of shunting of residual ASD and VSD.
• Assess truncal valve function.
• Assess AVV function.
• Assess arch after repair.

Acquisition

• Subcostal views

• Perform color Doppler sweeps to identify any residual ASD or VSD. If present, assess direction of shunting. Assess velocity of shunting across any residual VSD.
• Doppler abdominal aorta to assess pulsatility after arch repair.

• Apical views

• Assess MV and TV function. Obtain RV pressure estimate if possible.
• Assess LVOT.
• Assess truncal valve function, quantify regurgitation and/or stenosis as appropriate.

• Parasternal views

• Assess truncal valve regurgitation.
• Assess for residual VSD or additional VSD by color Doppler; obtain peak velocity if present.
• Assess RV-to-PA conduit for stenosis and regurgitation by color Doppler and spectral Doppler. Obtain mean gradient if conduit stenosis is present.
• Evaluate branch PAs for stenosis by color Doppler and spectral Doppler.
• Note that multiple levels or long segment narrowing in the pathway from the RV to the PAs may be present. Thus, careful PW Doppler analysis throughout this pathway must be performed to identify sites of obstruction. Mean gradient through the conduit may be more predictive of true peak-to-peak conduit gradient measured invasively.

• Suprasternal notch views

• If there is a history of interrupted aortic arch repair, assess the aortic arch with color Doppler and spectral Doppler as described in Chapter 12, Left Heart Anomalies.

Analysis

• Measure peak TR velocity to estimate RV pressure.
• Measure peak and mean conduit gradient and branch PA velocities.
• Quantify truncal (aortic) regurgitation as appropriate.
• Calculate arch gradient if present (may need to correct for V1).

Alternate Approaches

• MRI offers superior visualization of the conduit and branch PAs in postoperative patients with poor echocardiographic windows. In addition, RV size and function, conduit regurgitant fraction, and truncal valve regurgitant fraction can be calculated.
• Cardiac catheterization can provide accurate assessment of pressure gradients across the various levels of potential RVOTO as well as direct measurement of filling pressures. In addition, the option for intervention is available.
• Nuclear medicine lung perfusion scan quantifies relative pulmonary perfusion to the two lungs and can be used to help decide whether cardiac catheterization for branch PA dilation is warranted.

Key Points

• Repair entails patch closure of the VSD, removal of the PAs from the truncus, and insertion of an RV-to-PA conduit. The arch is repaired if interrupted.
• Postoperatively, evaluate for residual ASD or VSD, conduit function, and branch PA stenosis. Reassess truncal valve function; the velocity across the valve will likely have decreased compared with preoperatively due to a reduction in the volume load across the valve.
• On long-term follow-up, serial evaluation of RV size and function, conduit function, branch PA stenosis, truncal (aortic) valve function, and truncal (aortic) root dimensions is performed.

• If the aortic arch was repaired, it should be assessed serially on long-term follow-up.

Suggested Reading

1 Anderson RH, Weinberg PM. The clinical anatomy of tetralogy of Fallot. Cardiol Young. 2005;15(Suppl 1):38-47.

2 Hagler DJ. Double-outlet right and left ventricles. In: Eidem BW, Cetta F, O’Leary PW, editors. Echocardiography in Pediatric and Adult Congenital Heart Disease. Philadelphia: Lippincott Williams & Wilkins, 2010.

3 Jones FD, Fenstermaker B, Kovalchin JP. Truncus arteriosus. In: Eidem BW, Cetta F, O’Leary PW, editors. Echocardiography in Pediatric and Adult Congenital Heart Disease. Philadelphia: Lippincott Williams & Wilkins, 2010.

4 Lewin MB, Salerno JC. Truncus arteriosus. In: Lai WW, Mertens LL, Cohen MS, Geva T, editors. Echocardiography in Pediatric and Congenital Heart Disease. Hoboken, NJ: Wiley-Blackwell, 2009.

5 Lopez L. Double-outlet ventricle. In: Lai WW, Mertens LL, Cohen MS, Geva T, editors. Echocardiography in Pediatric and Congenital Heart Disease. Hoboken, NJ: Wiley-Blackwell, 2009.

6 Miller-Hance WC, Silverman NH. Transesophageal echocardiography in congenital heart disease with focus on the adult. Cardiol Clin. 2000;18(4):861-892.

7 Srivastava S, Parness IA. Tetralogy of Fallot. In: Lai WW, Mertens LL, Cohen MS, Geva T, editors. Echocardiography in Pediatric and Congenital Heart Disease. Hoboken, NJ: Wiley-Blackwell, 2009.

8 Mahle WT, Martinez R, Silverman N, Cohen MS, Anderson RH. Anatomy, echocardiography, and surgical approach to double outlet right ventricle. Cardiol Young. 2008;18(Suppl 3):39-51.

9 Vyas H, Eidem BW. Tetralogy of Fallot. In: Eidem BW, Cetta F, O’Leary PW, editors. Echocardiography in Pediatric and Adult Congenital Heart Disease. Lippincott Williams & Wilkins, 2010.

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