11 Right Heart Anomalies
Basic Principles
Right Ventricle
• There are three portions of a normally formed morphologic right ventricle (RV): inlet (supports the tricuspid valve [TV]), body (trabecular portion), and outlet (infundibulum or conal region).1
• The tripartite RV is loosely crescent shaped rather than conical shaped like the left ventricle (LV).
• Coarse muscular trabeculations and numerous small papillary muscles with attachments to both the septal and free walls further help to define a normal morphologic RV2 (Fig. 11-1).
Ebstein’s Anomaly
Background
• Ebstein’s anomaly (or malformation) is characterized by an increased downward (apical) displacement of the TV annulus caused by failure of delamination of the posterior and septal leaflets.3
• There is subsequent variable thinning of the wall of the “atrialized” RV (aRV) along with redundancy and tethering of the anterior leaflet of the TV.
• The clinical manifestations of Ebstein’s anomaly depend largely on the degree of severity of the TV displacement and the resultant physiologic effects.
• Right ventricular function becomes impaired and the abnormal TV becomes regurgitant, resulting in decreased forward flow through the pulmV.
• The combined right atrium (RA) and aRV becomes dilated with resultant right-to-left shunt across the interatrial septum (IAS).
• Clinically, infants with severe Ebstein’s anomaly will present with extreme cyanosis, cardiomegaly, and heart failure.
• Most patients with Ebstein’s anomaly will have other associated cardiac lesions. The most common associated lesion is an atrial septal communication, usually a patent foramen ovale (PFO), or secundum atrial septal defect (ASD). Other associated lesions include pulmV stenosis or atresia, ventricular septal defect (VSD), tetralogy of Fallot (TOF), left ventricular noncompaction (LVN), coarctation of the aorta (Ao), as well as other left-sided heart lesions. In congenitally corrected transposition of the great arteries (cc-TGA), the systemic left-sided TV may have some degree of Ebstein’s anomaly3–5 (Fig. 11-2).
Overview of Echocardiographic Approach
• The majority of clinically important information will be acquired with transthoracic two-dimensional (2D) imaging. The remaining physiologic data can be obtained with spectral and color Doppler.
Anatomic Imaging
Acquisition
• Transthoracic echo (TTE) in the neonate is the diagnostic gold standard and defines the severity of Ebstein’s anomaly.
• Parasternal long axis and short axis (PLAX and PSAX), subcostal long axis and short axis (SCLAX and SCSAX), and apical four-chamber (A4C) views are the most useful imaging planes to visualize the RA, IAS, TV, RV, and pulmV.
• Transesophageal echo (TEE) is used intraoperatively to assess the adequacy of the surgical repair.
• In the adult patient with Ebstein’s anomaly, TTE is usually adequate to visualize the right heart. However, TEE may be required if the TV leaflets are difficult to visualize with TTE.
Analysis
• The septal TV leaflet (and the posterior/inferior leaflet in severe forms) is apically displaced relative to the anterior leaflet of the MV. A displacement more than 0.8 cm/m2 is diagnostic of Ebstein’s anomaly. The A4C view best demonstrates the displacement and allows for measurement6 (Fig. 11-4).
• The profound right atrial dilation characteristic of Ebstein’s anomaly may best be seen in the A4C view, parasternal short axis view, and the subcostal view.
• Define the anatomy of the TV anterior, septal, and posterior leaflets (including attachments, tethering, dysplasia, and redundancy). The TV is best visualized from parasternal long axis and short axis, A4C, and subcostal views.5 Using an anatomic classification described by Carpentier et al.,7 a type A, B, C, or D category may be designated (Table 11-2). This classification can be helpful to the surgeon when considering whether to repair the TV6 (Fig. 11-5).
• The echocardiographic assessment of severity can be measured using the Great Ormond Street (GOS) ratio described by Celermajer et al.9 The ratio is obtained from the A4C view in end-diastole. It is the ratio of the area of the RA plus the area of the aRV compared with the area of the functional RV plus the left atrial and left ventricular areas (RA + aRV)/(RV + LA + LV). The increasing grade of severity is grade 1, ratio less than 0.5; grade 2, ratio 0.5 to 0.99; grade 3, ratio 1 to 1.49; grade 4, ratio greater than 1.5. Grades 3 and 4 have an increased risk of mortality9 (Fig. 11-6).
• Other important anatomic features to define include the normalized dimension of the TV annulus via Z score (usually at the level of the anterior leaflet proximal hinge points, where the true tricuspid annulus is located), the size of the ASD (if present), the presence or absence of a patent ductus arteriosus (PDA), and other associated cardiac anomalies (discussed previously).10
| Type A | Septal and posterior leaflet adherance without functional RV restriction of volume |
| Type B | Atrialized RV with normal anterior leaflet hinge point |
| Type C | Anterior leaflet stenosis |
| Type D | RV entirely atrialized except for a small infundibulum |
Data from Carpentier A, Chauvaud S, Mace L, et al. A new reconstructed operation for Ebstein’s anomaly of the tricuspid valve. J Thorac Cardiovasc Surg. 2006;132:1285–1290.
Pitfalls
• It is sometimes difficult to distinguish isolated TV dysplasia from true Ebstein’s anomaly. In TV dysplasia, the functional right ventricular chamber is usually larger and the TV orifice is directed to the apex of the RV. In Ebstein’s anomaly, the functional RV is usually smaller and the TV orifice is directed to the right ventricular outflow tract (RVOT).
Physiologic Data
Acquisition
• After a thorough description of the anatomy of Ebstein’s anomaly has been achieved, the physiologic characteristics of the lesion should be delineated.
• The use of pulsed wave (PW) Doppler, continuous wave (CW) Doppler, and color Doppler is of paramount importance to define the direction of blood flow through the heart: either forward flow through the RV and out the pulmV or reverse flow across the IAS to the LV, out the aortic valve (AV) and then across the PDA.
Analysis
• Focusing on the IAS from either the subcostal or parasternal view, use color Doppler along with PW Doppler to demonstrate the direction and velocity of shunting across the ASD. There is usually right-to-left atrial-level shunting in hemodynamically significant Ebstein’s anomaly (Fig. 11-7).
• From the A4C view as well as the parasternal and subcostal views, use color Doppler to demonstrate the severity of TV regurgitation (TR) and/or stenosis (TS). Use CW Doppler of the tricuspid regurgitant jet to estimate functional right ventricular pressure (Fig. 11-8).
• Investigate the pulmV with color Doppler, PW Doppler, and CW Doppler for forward flow, insufficiency, and stenosis from the parasternal short axis and long axis views as well as the subcostal views. This may be seen from an anteriorly directed apical view as well. Take special care to note pulmonary insufficiency (PI) in the setting of tricuspid regurgitation (TR), right-to-left atrial-level shunting, and left-to-right ductal shunting (the so-called circular shunt). Also pay special attention to the RVOT, as a large, redundant anterior leaflet of the TV can cause RV outflow tract obstruction (RVOTO). Some patients may exhibit “functional” pulmonary stenosis (PS) in which the valve leaflets fail to open in the setting of reduced right ventricular output and accompanying elevated pulmonary artery pressure (PAP) of the newborn. Pulmonary regurgitation can be a tip-off that the pulmonary valve will in fact eventually open when the PAP incrementally decreases.
• Right and left ventricular function should be evaluated. Pay attention to the size and wall motion of the RV. Measure left ventricular shortening fraction with M-mode measurements from the parasternal short axis view at the level of the papillary muscles.
• TEE can be helpful in the setting of surgical repair of Ebstein’s anomaly (TV repair/replacement or RV exclusion). The preoperative assessment should be used to confirm the anatomy found on TTE and further define the TV attachments if needed. Postoperatively, it is important to assess the TV repair (residual TR or TS) or the right ventricular exclusion patch fenestration depending on the surgical repair or palliation. Evaluate the IAS, ventricular function, MV pulmV function, and the PDA (if applicable) as well.
Alternate Approaches
• Usually a complete diagnosis can be made based on echocardiographic data alone in Ebstein’s anomaly.
• On rare occasions, if there are anatomic questions unable to be answered by echo (TTE or TEE), other imaging modalities can be considered including MRI or cardiac catheterization. Catheterization is particularly important if hemodynamic data are required.
Key Points
• Ebstein’s anomaly is characterized by an increased apical displacement of the TV annulus caused by failure of delamination of the posterior and septal leaflets.
• The TV is often regurgitant into the atrialized portion of the RV, causing severe right atrial enlargement and right-to-left flow across an ASD.
• The clinical manifestations of Ebstein’s anomaly depend largely on the severity of the TV displacement and the resultant physiologic effects. Infants with severe Ebstein’s anomaly will present with extreme cyanosis, cardiomegaly, and heart failure.
Pulmonary Atresia with Intact Ventricular Septum
Background
• Pulmonary atresia with intact ventricular septum (PA/IVS) is a rare and unique clinical entity in which the pulmV is atretic or imperforate and there is no interventricular communication.
• On the severe end of the spectrum, the pulmV is imperforate and the RV is severely hypoplastic. The TV is often dysplastic and hypoplastic as well. Due to the lack of egress of antegrade right ventricular blood flow, the right ventricular pressure is often suprasystemic. There is a higher incidence of coronary sinusoids from the RV in this scenario.
• RV-dependent coronary circulation (RVDCC) occurs in a small proportion of patients with PA/IVS. There may be stenosis that develops within the coronary artery system as well as ostial stenosis or atresia at the aortic cusp.5 As a result, the normal perfusion from oxygenated blood through the coronary arteries cannot take place. Instead, the perfusion to the myocardium becomes partially supplied by deoxygenated blood from the RV through coronary fistulous connections from persistent sinusoids. The presence of RVDCC has important clinical implications discussed further below.
• On the less severe end of the spectrum, patients can have pulmV atresia with a large or even dilated RV. These patients are less likely to have coronary sinusoids and more likely to have severe TR.
• Patients will initially require an intervention, either catheter based or surgical, to establish pulmonary blood flow (PBF). Depending on the severity of the lesion, including the presence or absence of RVDCC, the patient may eventually have a two-ventricle repair or a staged 1.5-ventricle or single-ventricle (SV) palliation.12–14
Overview of Echocardiographic Approach
TTE plays an integral role in defining the anatomy and clinical severity of patients with pulmonary atresia with IVS (Table 11-3).
• The goal of echo is to delineate the severity of right ventricular hypoplasia and related anatomy to help elucidate the physiology.
• In this lesion in particular, echo plays a complementary role to invasive diagnostic and interventional cardiac catheterization. One major complication of severe PA/IVS, RVDCC, cannot be identified with echo alone. The presence of RVDCC eliminates the possibility of a two-ventricle repair or a 1.5-ventricle palliation via opening the pulmV either surgically or interventionally and decompressing the RV.
Anatomic Imaging
Acquisition
• The initial 2D imaging should include defining the severity of right ventricular hypoplasia, measuring the TV Z score, evaluating the atretic pulmV and RVOT anatomy, identifying the main pulmonary artery (MPA) and branch pulmonary arteries, and identifying other associated lesions including a PFO and PDA.
Analysis
• As stated previously, the RV can be severely hypoplastic to severely dilated. The A4C view is a good place to start to get a sense of the size of the RV as well as the size of the inflow portion. By using multiple imaging plane sweeps (parasternal, subcostal), determine whether the RV is tripartite (inflow, body, and outflow) (Fig. 11-10).
• The majority of patients who have hypoplasia of the RV will also have hypoplasia of the TV.14 Measure the annulus of the TV from the apical and parasternal long axis planes (with Z score). The Z score of the TV and the degree of right ventricular hypoplasia will influence the type of clinical management; single ventricle versus two-ventricle palliation or repair13 (Fig. 11-11).
• Evaluate the RVOT from PLAX, PSAX, and SC views. Determine whether there is a well-formed infundibulum, a moderately hypoplastic RVOT that tapers down but ends in close proximity to the atretic pulmV or a severely hypoplastic RVOT (muscular pulmonary atresia) that terminates remotely from the pulmV. These details are important to the interventionalist if consideration is being given to opening the pulmV with radiofrequency perforation and balloon valvuloplasty.
• Image the pulmV and describe the appearance of the valve leaflets. Determine if there are thickened and fused leaflets with a well-formed pulmonary annulus. Measure the diameter of the pulmV annulus. An en face view of the pulmV can be obtained in a high parasternal short axis view by rotating the transducer away from the aortic valve until the pulmV comes into view (Fig. 11-12).
• Image the MPA segment as well as the presence or absence of confluent branch PAs. Measure the diameter of the MPA and branch PAs with the Z score. The SSN and PSAX view may be the most helpful.
• Identify other associated cardiac lesions including a PFO or an ASD and a PDA. It is extremely uncommon to have left-sided cardiac lesions (like coarctation of the aorta) and PA/IVS. There may rarely be left ventricular outflow tract obstruction seen due to bowing of the interventricular septum from a suprasystemic RV.
Figure 11-10 Apical view. Note the severely hypoplastic RV. A small inlet portion of the RV is seen in this image.
Physiologic Data
Analysis
• The first step is to determine whether the pulmV is functionally or completely atretic. Use color Doppler across the pulmV with a low Nyquist limit to evaluate for any evidence of antegrade PBF or PI (Fig. 11-13).
• Evaluate the degree of TR with color Doppler. A dilated RV will likely have significant TR, whereas a hypoplastic TV and RV may have very little TR. If present, use CW Doppler to obtain a peak TR velocity to estimate right ventricular pressure (including an estimate of right atrial pressure).
• In the PSAX view, identify the origins and proximal course of the right and left coronary arteries with 2D imaging and color Doppler. Attempt to demonstrate the direction of proximal coronary blood flow. Take note that if there is RVDCC, there may not be normal proximal coronary blood flow in one or both of the coronary arteries.
• Attempt to demonstrate coronary sinusoids. With the Nyquist limit turned very low, it is sometimes possible to capture the flow of coronary sinusoids over the right ventricular myocardium. If they are present, if does not necessarily indicate RVDCC. A cardiac catheterization must be performed with a right ventricular injection. However, patients with tricuspid annulus Z scores greater than −2.5 are less likely to have coronary sinusoids and RVDCC by catheterizations.16
• Assess right and left ventricular function, paying attention to regional wall motion abnormalities.
• Evaluate the direction of flow across the IAS using color Doppler. There is a right-to-left shunt in patients with PA/IVS. Take note of color turbulence at the defect indicating a possible restrictive IAS. Use PW Doppler to interrogate the peak velocity across the defect. Also note whether there is one or multiple defects (Fig. 11-14).
• Patients with PA/IVS are dependent on a PDA for PBF. Use color Doppler and spectral Doppler to interrogate the PDA. The flow should be left to right.
Alternate Approaches
• Cardiac catheterization is used as a diagnostic tool to identify RVDCC. Catheterization also is used interventionally to open the pulmV when there is a formed RVOT and valve plate that will lend itself to either crossing through a small opening or via radiofrequency perforation and balloon valvuloplasty. This procedure may be attempted once RVDCC is excluded.
Key Points
• PA/IVS is a rare and unique clinical entity in which the pulmV is atretic or imperforate and there is no interventricular communication.
• There is a spectrum of disease severity seen ranging from a severely hypoplastic RV and TV to a dilated RV and regurgitant TV.
• In this lesion in particular, echo plays a complementary role to invasive diagnostic and possibly interventional cardiac catheterization because one major but rare complication, RVDCC, cannot be diagnosed with echo alone.
Pulmonary Stenosis
Background
• Most causes of native pulmV stenosis are congenital. Isolated pulmV stenosis can occur due to three typical valve types: doming pulmV (most commonly fusion of valve leaflets), dysplastic pulmV (thickened leaflets with poor mobility), or an abnormal number of cusps (unicuspid, bicuspid, quadricuspid). The latter form of pulmV stenosis is usually seen in conjunction with other forms of congenital heart disease (CHD) rather than in isolation.
• PulmV stenosis is also seen with several genetic syndromes or disorders including Noonan syndrome, Alagille syndrome, Williams syndrome, and congenital rubella.
• Stenosis may occur below the pulmV (subvalvar) in association with other CHD such as TOF or as a result of the development of infundibular muscle bundle hypertrophy (double-chamber RV [DCRV]) because of concomitant VSD jet lesions and right ventricular hypertension. Other rare causes of RVOT obstruction include hypertrophic cardiomyopathy or an infiltrative process such as Pompe disease.16
• Stenosis above the pulmV (supravalvar) may occur in association with the mentioned genetic disorders as well as in isolation.
• Most patients with PS are asymptomatic, even with moderate to severe stenosis. Mild PS does not tend to progress outside of the neonatal period and may improve over time.
• Those patients with moderate to severe disease with or without symptoms may benefit from catheter-based or surgical valve opening based on well-documented recommendations by the American College of Cardiology and the American Heart Association (ACC/AHA).17
• The dysplastic type of pulmV stenosis usually is not amenable to catheter-based valvuloplasty and requires surgical intervention.
• Clinical consequences of PS include right ventricular hypertrophy (RVH), increased right ventricular systolic and diastolic pressures, and eventual right-to-left shunting across a PFO if one is present. The degree of RVH and upstream effects is related to the severity of the stenosis.
Overview of Echocardiographic Approach
• The echocardiographer should attempt to demonstrate the morphology of the pulmV, the degree of stenosis, the degree of RVH, evaluate for TR and atrial-level shunting.
• The precise data obtained by echo will largely dictate the clinical management to follow (Table 11-4).
Anatomic Imaging
Acquisition
• TTE of the neonate or child is usually the mainstay for the initial diagnosis and grading of severity.
Analysis
• The first step is to evaluate the pulmV morphology with 2D imaging. Identify whether the valve is doming with fusion of the leaflet cusps, is dysplastic with thickened and poorly mobile leaflets, or has an abnormal number of cusps. The pulmV function and leaflet morphology are best visualized in the parasternal and subcostal views. Measure the valve annulus in systole (including calculation of valve dimension Z score) (Fig. 11-17). Stenotic pulmV can be hypoplastic as can be seen in critical neonatal PS. To identify the number of cusps, the valve must be seen in an en face view. This is best accomplished in a higher parasternal view with slight rotation of the transducer away from the aortic valve until the pulmV comes into view (Fig. 11-18).
• The next step is to evaluate the subvalvar region for evidence of RVOT narrowing or infundibular muscle hypertrophy. There can be a ridge of tissue causing obstruction toward the proximal end of the infundibulum seen best in the PSAX view. There may also be muscle bundle hypertrophy or accessory muscle bundles that can divide the right ventricular body into proximal and distal chambers (DCRV). This is best seen in the subcostal anterior oblique view (the same view that is used to evaluate the infundibular area in TOF).
• Assess the degree of RVH and systolic function in the A4C view as well as PLAX and SC views. The amount of hypertrophy is relative to the degree of PS.
• Evaluate the IAS for a PFO or ASD. Measure the diameter. This is best seen in the standard atrial septal views (subcostal, PSAX, right parasternal).
• Assess for supravalvar PS. Measure the diameter of the MPA and the area of narrowing seen due to either a discrete ridge of tissue or a narrowed vessel. Measure both branch PAs. The MPA and branches are best visualized from PSAX/PLAX as well as SSN and high left parasternal views.
• Assess for the presence of a PDA. If present, measure the diameter of the ampulla. The PDA is best seen in the high left parasternal view.
• Measure the TV annulus (with calculation of Z score) and note the morphology of the TV. In cases of severe PS, the TV may be hypoplastic and/or dysplastic.19
Pitfalls
• In the adult patient with poor subcostal windows, parasternal views along with color Doppler information are relied on more heavily. It can be difficult to obtain clear 2D imaging of subvalvar PS, but color Doppler information from parasternal long axis and short axis should assist with the diagnosis.5
Physiologic Data
Acquisition
• The quantitative assessment of the severity of PS is based on the systolic pressure gradient across the area of stenosis.
• Use color Doppler across the RVOT and pulmV with the Nyquist limit at its maximum to get a sense for where the flow turbulence begins (below, at, or above the valve).
• Using CW Doppler and the modified Bernoulli equation, the peak velocity across the site of stenosis can be acquired. Trace the full envelope to calculate the mean pressure gradient (Fig. 11-20).
• It is also important to use PW Doppler to measure the peak velocity below the valve, at the valve, and above the valve to determine the level of obstruction (or the relative contribution of multiple sites of stenosis) (Figs. 11-21 and 11-22).
• The highest velocity from multiple different planes should be used. In children, the Doppler angle will be the most accurate from SC or PSAX views. In adults without subcostal views, the best angle of interrogation will usually be on the PSAX view.
• If the pulmV is interrogated intraoperatively with TEE, a transgastric view or a midesophageal view will align the Doppler angle the most accurately.
Analysis
• In 2006, the AHA and ACC defined grades of severity of PS based on systolic peak velocity or maximal instantaneous pressure gradients (MIPGs).18 Grading is as follows:
• Both the peak and mean systolic pressure gradients should be reported. In general, the peak-to-peak gradient measured in the cardiac catheterization laboratory is lower than the Doppler-derived MIPG. Some would argue that the mean Doppler gradient measured correlates better with the catheterization measured peak-to peak gradient.20
• If TR is present, measure the CW Doppler pressure gradient to estimate right ventricular pressure (plus right atrial pressure).
• Demonstrate the atrial-level shunting with color Doppler and PW Doppler if there is a PFO or ASD present. The direction of blood flow should be left to right except in cases of severe or critical PS where there may be right-to-left shunting across the IAS from decreased right ventricular compliance or right ventricular outflow obstruction.
• If present, demonstrate the direction of flow across a PDA. Use PW Doppler to estimate the peak systolic velocity. This, along with knowledge of systemic systolic blood pressure, will allow for calculation of the downstream (poststenosis) PAP. In combination with the CW Doppler velocity across the region of stenosis, a calculation can then be performed to estimate right ventricular systolic pressure.
• Qualitatively assess the right ventricular function. Also note the interventricular septal position. A flattened interventricular septum is indirect evidence of elevated right ventricular pressure.21
• After intervention on the pulmV (either catheter based or surgically), the residual stenosis gradient should be assessed as well as evidence of PI. In a rare case, subvalvar (infundibular) stenosis can develop after the valvar PS is relieved (the “suicide” RV). This obstruction is dynamic in nature. The Doppler profile will be consistent with a dynamic rather than a fixed obstruction.
Alternate Approaches
• In most cases of PS, echo with 2D, Doppler, and color Doppler information can accurately define the anatomic reasons for and severity of the stenosis.
• On rare occasions, other imaging modalities, such as MRI or computed tomography (CT), can be beneficial.
• Cardiac catheterization is usually not required for diagnostic purposes but reserved for interventions for PS.
Key Points
• Most causes of native pulmV stenosis are congenital. Isolated pulmV stenosis can occur due to three typical valve types: doming pulmV (most common, fusion of valve leaflets), dysplastic pulmV (thickened leaflets with poor mobility), or an abnormal number of cusps (unicuspid, bicuspid, quadricuspid).
• Obstruction below the pulmV (subvalvar) or above the valve (supravalvar) may be seen in isolation or in conjunction with pulmV stenosis.
• Echo is the primary tool used to define the anatomic reasons for PS as well as define the degree of severity. No further diagnostic tools should be required if the echocardiogram is complete and precisely executed.
• Using 2D imaging, fully demonstrate the anatomy and size of the pulmV as well as subvalvar or supravalvar narrowing if present. Other important features to define with 2D imaging are the presence of an ASD or PDA, the appearance of the TV, and the qualitative assessment of right ventricular function.
Branch Pulmonary Artery Stenosis
Background
• As with valvar PS, branch PA stenosis has a wide variation in its clinical presentation, subsequent course, and sequelae.
• In infants, physiologic branch PA stenosis often presents as a short systolic murmur in an asymptomatic neonate. On echocardiographic investigation, the branch PAs are found to be slightly smaller than normal with mild flow turbulence through the right and left PAs (usually <2 m/s). The stenosis is usually bilateral and tends to regress without the need for any intervention by about 3 months of age.22
• Other forms of branch PA stenosis can be unilateral or bilateral and are often found in conjunction with other CHD (e.g., TOF, pulmonary atresia with VSD, other cyanotic heart defects), genetic syndromes (Williams, Noonan, Alagille), or acquired after cardiac surgery (e.g., after the LeCompte maneuver in an arterial switch operation for dextro transposition of the great arteries [d-TGA] repair, unifocalization of major aortopulmonary collaterals).
Overview of Echocardiographic Approach
• Careful 2D and Doppler evaluation of the branch PAs will reveal most clinically important information with a few exceptions (see the following Pitfalls section).
Anatomic imaging
Acquisition
• The branch PAs are well visualized from the PSAX and PLAX views. The SSN views and the high left parasternal views are also helpful but may be more challenging in the adult patient.
• With 2D imaging, measure the diameter of the branch PAs and any discrete narrowing seen. Measure the MPA as well (Fig. 11-23).
Analysis
• Report the Z scores of the 2D measurements of the right PA, left PA, MPA, and pulmV annulus. In physiologic branch PA stenosis, the right and left PAs may be mildly hypoplastic (on the order of 4 mm in the full-term infant), but the MPA and pulmV are typically normal.22
• Determine whether there is a discrete ostial stenosis to one or both branch PAs versus diffuse long-segment hypoplasia (Fig. 11-24).
• The branch PA abnormalities associated with specific cardiac lesions are discussed in their respective chapters.
• Assess for signs of severe stenosis. Look for evidence of elevated right ventricular pressure (IVS position), RVH, and RV systolic function.
Pitfalls
• In cases of unilateral branch PA stenosis, there is decreased blood flow through the stenotic vessel and increased flow through the opposite vessel. The nonstenotic vessel may appear larger on 2D measurements, and the RV may or may not have evidence of elevated pressure.
• Postsurgical imaging of branch PAs is discussed in their respective chapters (i.e., imaging the branch PAs in their atypical orientation after a LeCompte maneuver for d-TGA) (Fig. 11-25).
Physiologic Data
Acquisition
• After 2D imaging, data are gathered; spectral and color Doppler information should be obtained to quantify the degree of stenosis.
• Color Doppler across the MPA and branch PAs will identify the site(s) of flow turbulence. Also take note of flow reversal, where the flow reversal begins, and the degree of PI. Be sure to maximize the Nyquist limit (Fig. 11-26).
Figure 11-26 PSAX images in an infant with bilateral branch PA stenosis. This is the same patient as in Figure 11-23. A, Color Doppler demonstrating flow turbulence in the RPA. B, Color Doppler demonstrating flow turbulence in the LPA. C, Spectral Doppler of the RPA showing stenosis (peak velocity 1.81 m/s). D, Spectral Doppler of the LPA showing stenosis (peak velocity 2.38 m/s).
Analysis
• Unlike pulmV stenosis, there is not a specific severity grading scale for branch PA stenosis. There are anatomic issues that can complicate the interpretation of Doppler-derived velocity information (see the following Pitfalls section).
• PW Doppler profiles should be obtained in each branch PA, MPA, and pulmV. A CW Doppler profile can be obtained as well, although it may not give specific information as to the site of the obstruction. If the branch PA stenosis is being followed at serial clinic visits, it is important to measure the velocity in similar locations and views with similar echo settings at each visit so that a reasonable comparison can be made over time. It is also important to align the Doppler angle with the stenotic jet to minimize error.
• If TR is present, measure the CW Doppler pressure gradient to estimate RV pressure (plus right atrial pressure).
• Demonstrate the atrial-level shunting with color Doppler and PW Doppler if there is a PFO or ASD present. The direction of blood flow should be left to right except in cases of severe branch PS in which there may be right-to-left shunting across the IAS.
Pitfalls
• In unilateral branch PA stenosis, there can be increased blood flow through the opposite branch PA with an increased flow velocity recorded with PW Doppler and turbulence seen on color Doppler interrogation. The stenotic vessel will have decreased blood flow. For this reason, the velocity across this vessel may not be an accurate predictor of the severity of stenosis.
Alternate Approaches
• In cases of unilateral branch PA stenosis, a lung perfusion study will help to clarify the percentage of blood flow going to each lung field. This information may assist the clinician in assessing the severity of stenosis.
• Occasionally the branch PAs are difficult to visualize well by echo. In these cases, MRI or CT could be considered to augment echo information.
• Catheterization is usually reserved for intervention on branch PA stenosis. Once the stenosis is deemed severe enough (based on clinical symptoms, echo, lung perfusion scan, and/or MRI information), the pressure gradient can be assessed invasively before possible intervention.24,25
Key Points
• In infants, physiologic branch PA stenosis often presents as a short systolic murmur in an asymptomatic neonate. The branch PAs are found to be slightly smaller than normal with mild flow turbulence through the right and LPAs (usually <2 m/s). Stenosis tends to regress by about 3 months of age without the need for intervention.
• Other forms of branch PA stenosis can be unilateral or bilateral and are often found in conjunction with other CHD or genetic syndromes or acquired after cardiac surgery.
• Color Doppler across the MPA and branch PAs will identify the site(s) of flow turbulence as well as flow reversal and the degree of PI.
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1 Attenhofer Jost CH, Connolly HM, Dearani JA, et al. Ebstein’s anomaly. Circulation. 2007;115:277-285.
2 Paranon S, Acar P. Ebstein’s anomaly of the tricuspid valve: from fetus to adult: congenital heart disease. Heart. 2008;94:237-243.
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4 Powell AJ, Mayer JE, Lang P, Lock JE. Outcome in infants with pulmonary atresia, intact ventricular septum, and right ventricle-dependent coronary circulation. Am J Cardiol. 2000;86(11):1272-1274.
5 Odim J, Laks H, Plunkett MD, Tung TC. Successful management of patients with pulmonary atresia with intact ventricular septum using a three tier grading system for right ventricular hypoplasia. Ann Thorac Surg. 2006;81:678-684.
6 ACC/AHA 2006 Guidelines for the Management of Patients With Valvular Heart Disease: A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the 1998 Guidelines for the Management of Patients With Valvular Heart Disease). Circulation. 2006;114:e84-e231.
7 Silvilairat S, Cabalka AK, Cetta F, et al. Echocardiographic assessment of isolated pulmonary valve stenosis: which outpatient Doppler gradient has the most clinical validity? J Am Soc Echocardiogr. 2005;18:1137-1142.
8 Frank DU, Minich LL, Shaddy RE, Tani LY. Is Doppler an accurate predictor of catheterization gradients for postoperative branch pulmonary stenosis? J Am Soc Echocardiogr. 2002;15(10 Pt 2):1140-1144.
