History and natural history

Lack of awareness of their CHD and the anatomical diagnosis is commonplace among adult patients for whom diagnosis and possible intervention occurred early in life. Information about procedures was provided to the parents, not to the current adult patient, whose understanding will be modified by time and the second telling. If the patient knows the diagnosis, this provides important information to the sonographer that can be beneficial while performing an echocardiogram. Patients without the particulars of diagnosis might use statements such as, “My arteries were backwards,” which might mean transposition of great arteries, or “I was born with half a heart,” which might mean a single ventricle of some sort. The statement “I had a hole in my heart” can have many meanings ranging from simple to complex problems. Patients may refer to their defect as a “heart murmur,” with no understanding of the implications.

If medical records are available, it is worth spending time reviewing this information before initiating an echocardiographic study. If records are not available, clinicians should make every attempt to procure them from the treatment facility, which is often known. Specific knowledge of surgical procedures is vital to understanding the patient and interpreting the echocardiogram. Subtle, but important, details such as an absent pulmonary artery or a right-sided aortic arch will make the echocardiographic examination much smoother and less confusing.

The natural history of CHD will vary tremendously depending on the defect. Not all CHD is lethal. CHD occurs in about 0.8% of live births. In the current era of significantly improved survival, ^, adults with complex CHD have outnumbered children. ^, The total number of adults with CHD is estimated to be over 1 million. Patients who claim to have congenital heart disease will be more likely to have a defect which is more prevalent. The actual prevalence of various forms of CHD will vary depending on the study cited or methodology used for diagnosis. Bicuspid aortic valve is likely the most common “defect” but is often left out of many lists of CHD. Ventricular septal defect is the most common CHD, comprising 18% to 28% of the total. A list of the rough incidence percentages of CHD is shown in Table 165.1 . ^, When performing an echocardiogram on an uninformed adult with CHD, knowledge of what is most commonly found is helpful.

Details such as the year of surgery and the total number of surgeries a patient has gone through may help to define the type of surgical repair the patient might have had. A detailed listing of surgical procedures is provided in another chapter. Sometimes obtaining this knowledge takes some detective work on the part of the sonographer/ cardiologist. A good example is the case of d-transposition of great arteries (D-TGA). In 1954 surgeons began performing the atrial switch operation (Mustard/Senning procedure). The first arterial switch operation (Jatene procedure) was performed in 1976. Acceptance of this newer procedure was not immediate. So a patient born before 1976 or between 1976 and 1980 who underwent surgical repair for D-TGA is unlikely to have an arterial switch operation and more likely to have had the atrial switch repair. It is also important to know if the patient had any form of catheter-based intervention such as a device or a stent, which were not common before the mid-1990s. Many patients may also confuse a catheter-based intervention or even a diagnostic catheterization with a “surgery.”

Location of the scar: “the scar is the clue”

Timing for the congenital cardiac operations has changed over the years, with fewer early palliative operations and earlier primary repair ( Table 165.2 ). Primary open heart repair using cardiopulmonary bypass is most frequently performed through a median sternotomy and a midline chest incision. By contrast, in earlier years, palliative operations were frequently performed using lateral or posterolateral thoracotomies. A midline sternotomy scar versus a right or left lateral thoracotomy scar can help discern the probable surgical repair and in some cases the possible diagnosis. Some of the operations that could be performed without opening the heart were performed via a lateral thoracotomy ( Fig. 165.1 ).

Schematic representation of the chest incisions and the likely congenital heart operations which may be performed through that approach. This information can be very helpful when the patient is unaware of the procedure or procedures that were performed. ASD, Atrial septal defect; PDA, patent ductus arteriosus; VSD, ventricular septal defect.

Segmental analysis

An echocardiographic strategy, which encompasses identification of the blood flow in CHD, is called segmental analysis . This includes systematic determination of the position of the apex, situs of the atrium, the atrioventricular relationship, and the ventriculoarterial relationship. Every patient getting an echocardiogram has blood moving into and out of the heart. For survival, the basic components of cardiac anatomy need to be present. In CHD, the pathway that the blood takes is the issue of interest. This is of particular importance in complex CHD at the time of initial diagnosis. Standard ASE imaging protocols ^, will allow the examiner to identify these points of anatomic interest. It is the thinking, not necessarily the protocol, that needs emphasis in terms of segmental analysis. Segmental thinking includes:

• 1.
  

  Cardiac position and visceral situs

  
  
  
  
  • a.
    

    Position of the heart in the chest, visceral situs

    
    
  • b.
    

    Relative position of the atria

    
    
  • c.
    

    Relative position of the ventricles, identified morphologically

  
  
  
  
• 2.
  

  Blood flow into the heart

  
  
  
  
  • a.
    

    Identification of systemic veins

    
    
  • b.
    

    Identification of pulmonary veins

    
    
  • c.
    

    Identification of venous anomalies

  
  
  
  
• 3.
  

  Blood flow through the heart

  
  
  
  
  • a.
    

    Atrioventricular connections, identified morphologically

    
    
  • b.
    

    Ventriculoarterial connections, identified morphologically

    
    
  • c.
    

    Shunts

    
    
  • d.
    

    Obstructions

  
  
  
  
• 4.
  

  Blood flow out of the heart

  
  
  
  
  • a.
    

    Aortic arch patency and branching pattern

    
    
  • b.
    

    Pulmonary artery bifurcation, size, and patency

    
    
  • c.
    

    Presence/size of the ductus arteriosus

  
  
  
  
• 5.
  

  Coronary artery anatomy

Special pediatric views and their significance

As defined by American Society of Echocardiography, five different locations including subcostal/ subxiphoid, apical, left parasternal, right parasternal, and suprasternal views are used for performing a detailed pediatric echocardiogram. In this chapter we describe some of the special pediatric views and their role in defining CHD.

The ductal view is obtained by aligning the transducer in a sagittal plane from a high left parasternal location (notch positioned between 12 and 1 o’clock position) ( Fig. 165.4 ). This view aligns the main pulmonary artery, the ductus arteriosus, and the descending aorta in a single plane. Color flow mapping helps confirm the absence or presence of a ductal patency and the direction of blood flow in this vessel. This view also allows a better visualization of ductal size. In cases with a good echocardiographic window, this view is also excellent for visualization of the isthmus (narrowest portion of the arch) and the upper descending aorta. Hence, this view is of particular significance in recognizing the presence and severity of coarctation of the aorta.

The “ductal view” is obtained by placing the transducer in a sagittal orientation from a high left parasternal location with the indicator notch directly superior. The main pulmonary artery (PA) , the patent ductus arteriosus (PDA) , and the descending aorta (Desc Ao) are all seen in a continuation. Color flow mapping is an essential part of imaging. However, recognition of blue flow (representing right-to-left ductus) requires caution. LA, Left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle. (See accompanying Video 165.4.)

The subcostal/subxiphoid long-axis view (four-chamber view) is useful for evaluating atrial chamber size and particularly for visualization of the atrial septum. The transducer is pointed at the left shoulder, and the indicator notch is to the patient’s left. Color flow mapping from this view is very helpful in identifying the presence of atrial-level shunting, as well as its magnitude and direction ( Fig. 165.5 ). In patients with poor subxiphoid windows, the left parasternal short-axis view may be used to visualize the atrial septum (transducer in left parasternal location and notch directed at 3 o’clock position). The right ventricular outflow view is obtained by rotating the transducer 45 degrees counterclockwise from the subcostal/subxiphoid long-axis view and angulating anteriorly ( Fig. 165.6 ). This is an excellent view for evaluating the right ventricular outflow tract, particularly when there is suspected stenosis or hypoplasia.

The subcostal four-chamber view is useful for evaluating atrial chamber size and particularly for looking at the atrial septum. It is obtained from the subxiphoid space with the transducer pointed at the left shoulder and the indicator notch to the patient’s left. LA, Left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle. (See accompanying Video 165.5.)

The right ventricle (RV) outflow view is obtained by rotating the transducer 45 degrees counterclockwise from the subcostal four-chamber view. This is an excellent view for evaluating the entire right ventricular outflow tract, particularly when there is stenosis or hypoplasia at one or more levels along the tract. This view offers good alignment for Doppler assessment. MPA, Main pulmonary artery; RA, right atrium. (See accompanying Video 165.6.)

Aortic arch pathology is more prevalent with CHD, making imaging of this structure an important part of the examination. The aortic arch is best visualized from a suprasternal long-axis view (transducer in the suprasternal notch and parallel to a plane between the left shoulder and right hip). The transducer indicator notch is approximately at the 1 o’clock position with the patient positioned supine with head and neck extended with the help of a wedge under the shoulder ( Fig. 165.7 ). The suprasternal short-axis view is obtained by rotating the transducer clockwise about 60 degrees from the long-axis view (indicator notch at the 3 o’clock position) and is useful for evaluating pulmonary veins as well as the superior vena cava ( Fig. 165.8 ). This is also an excellent view for visualization of the right pulmonary artery, which is used as a landmark for this view. While in the suprasternal short-axis view, with some further clockwise rotation and superior tilt toward the shoulder, the branching pattern of the innominate artery may be visualized to aid in identification of arch sidedness ( Fig. 165.9 ).

Arch configuration and patency may be obtained from the suprasternal long-axis view, with the transducer in the suprasternal notch and the transducer parallel to a plane between the left shoulder and right hip. Specific attention to the distance between head and neck vessels and color flow mapping may be necessary in patients with coarctation. AV, Aortic valve; Innom. artery. innominate artery; LCCA, left common carotid artery; LSCA, left subclavian artery; RPA, right pulmonary artery. (See accompanying Video 165.7.)

Suprasternal short-axis views are obtained by rotating the transducer about 60 degrees in clockwise direction from the suprasternal long axis view. This view is very useful for evaluating pulmonary veins as well as the superior vena cava (SVC) . This is also an excellent view for assessment of the right pulmonary artery (RPA) , which is used as a landmark for obtaining the view. Ao, Aorta; Innom. vein, innominate vein; LA, left atrium; LLPV, left lower pulmonary vein; LUPV, left upper pulmonary vein; MPA, main pulmonary artery; RLPV, right lower pulmonary vein; RUPV, right upper pulmonary vein. (See accompanying Video 165.8, A and B .)

From the suprasternal short-axis view, further clockwise rotation and slight angulation of the transducer toward the contralateral shoulder will demonstrate the branching pattern of the innominate artery as an aid in identification of arch sidedness. First branch going to the right side and bifurcating suggests a left arch, and first branch going to the left and bifurcating suggests a mirror-image right arch. Ao, Aorta; LCCA, left common carotid artery; LSCA, left subclavian artery; RCCA, right common carotid artery; RSCA, right subclavian artery. (See accompanying Video 165.9.)

Sweeps are important to establish relationships between contiguous structures. The left parasternal short-axis sweep (transducer in left parasternal position, notch pointing toward 2 o’clock position) begins with the transducer tilted toward the right shoulder and progresses from the base of the heart to the apex. This sweep is particularly important for evaluating the ventricular septum. This is useful in the two-dimensional exam as well as in color flow mapping. While sweeping toward the apex, it may be necessary to slide the transducer inferiorly between rib interspaces toward the cardiac apex in an attempt to cover the entire ventricular septum, particularly the apical muscular septum ( Fig. 165.10 ). In addition to the ventricular septum and the details of the aortic and pulmonary valve, this view is excellent for visualization of the mitral valve and papillary muscles.

Sweeps are important to establish relationships between contiguous structures. The parasternal short-axis sweep is performed from a parasternal location with transducer in a short-axis plane. This view is particularly important for evaluating the entire ventricular septum from the base to the apex and also the mitral valve apparatus. Color flow mapping aids the diagnosis of shunts across the ventricular septum and also valvular regurgitation. (See accompanying Video 165.10.)

Role of transesophageal echocardiography in an adult patient with congenital heart disease

The indications for TEE in an adult patient with CHD include diagnosis and guidance during percutaneous interventions and during surgical repairs (intraoperative). In the presence of technical limitations such as poor acoustic windows, TEE can be extremely helpful in adults with CHD for establishing a diagnosis and guiding their management. TEE offers better visualization of interatrial shunts, pulmonary venous drainage, aortic dissection, abscesses or vegetations, intracardiac thrombus, intracardiac baffles, and prosthetic valves when compared to transthoracic echocardiography (TTE). Surgical baffles and conduits may be better visualized by TEE as compared with TTE. ^, In the interventional cardiac laboratory and operating room, TEE is an extremely helpful modality of cardiac imaging and a standard of care. ^, The utility of TEE may be regarded as an alternative to cardiac magnetic resonance (CMR) imaging in certain cases or as an adjunct to it in other cases. Depending on the questions being asked and the setting, one may be preferred over the other. CMR may provide additional information in cases of intracardiac baffles, extracardiac baffles, and conduits. ^, CMR is now the imaging test of choice in adult patients with tetralogy of Fallot for quantification of right ventricular volumes, estimation of pulmonary regurgitation fraction, and quantification of other shunt flows and collateral flow. It is also the recommended imaging test for measurement of aortic root size in patients with bicuspid aortic valve or Marfan syndrome. Intracardiac echocardiography (ICE) is now being increasingly used for interventional procedures in some centers. Three-dimensional TEE is now available and being used for diagnostic and interventional purposes. ^, Hahn and colleagues describe specific TEE views recommended in specific diagnostic scenarios for adult patients with CHD. Hahn and colleagues also alert clinicians to the sedation requirements of this group of patients during a TEE and the need for closer monitoring.

Summary

• •
  

  History is the key (including the surgical details).

  
  
• •
  

  Be a detective—find out when the repair was done, where the scar is, and so on.

  
  
• •
  

  Know which operations are done through the side versus midline incision.

  
  
• •
  

  Know the timeline of the various surgical repairs and which procedure is currently being done compared with those that are now abandoned.

  
  
• •
  

  Understand the segmental approach to the identification of cardiac anatomy.

  
  
• •
  

  Know the specific morphologic characteristics of all the cardiac structures/chambers (see Chapter 169 ).

  
  
• •
  

  Know and practice the special pediatric views.

  
  
• •
  

  Know the commonly occurring complications and consequences of various forms of CHD.

  
  
• •
  

  Understand the role of TEE, ICE, and CMR in these patients.

Anatomy of the outflow tracts and thoracic aorta

The normal outflow tract can be divided into three anatomic segments: the subarterial region, the semilunar valve, and the proximal great artery. The conus or infundibulum represents the subarterial muscular chamber separating the atrioventricular valve from the corresponding semilunar valve. In the normal heart, the subpulmonary conus is separated from the trabecular segment of the RV chamber at the infundibular os defined by the moderator, septal, and parietal bands.

The normal semilunar valve consists of three leaflets with three-dimensional attachments in a semilunar or crownlike fashion within the arterial root extending from the ventriculoarterial junction to the sinotubular junction. Hence the term “annulus” used for the semilunar valve in echocardiography is in fact a diagnostician construct without a true anatomic correlate, because this area represents only the most proximal attachments of the semilunar valve at the ventriculoarterial junction. The leaflets are separated by three commissures extending during diastole from the center of the valve at the level of the ventriculoarterial junction to the arterial wall at the level of the sinotubular junction.

The thoracic aorta may be divided into five segments: (1) ascending aorta, including the aortic root; (2) proximal transverse arch, between the right innominate (brachiocephalic) and left common carotid arteries; (3) distal transverse arch, between the left common carotid and left subclavian arteries; (4) isthmus, between the left subclavian artery and the ligamentum or ductus arteriosus; and (5) descending aorta. The aortic arch is left-sided (traveling to the left of the trachea) in over 99% of patients. Several generally benign variants in branching pattern are found, including (1) common origin of the right innominate and left common carotid arteries (incorrectly referred to as a “bovine arch”), (2) aortic origin of the left vertebral artery, and (3) aberrant right subclavian artery with separate origin of the right subclavian artery distal to the left subclavian artery origin.

Clinical presentation

Obstructive lesions are associated with a pressure-overloaded ventricle, often accompanied by progressive hypertrophy and fibrosis. Patients with these problems generally present with a systolic murmur whose location is determined by the affected outflow tract and whose frequency and intensity are determined by the degree of obstruction. Occasionally, a systolic click is heard. Symptoms in children are rare, though severe obstruction can be associated with chest pain, syncope, and/or exercise intolerance, particularly for LV outflow obstruction. Rarely older children and adults will present with signs of RV or LV failure, as severe hypertrophy can result in progressive diastolic and systolic dysfunction. Severe outflow tract obstruction in the newborn period often involves severe ventricular dysfunction, atrioventricular valve regurgitation, and compromised cardiac output. In cases of critical AS or PS associated with inadequate cardiac output, ductal patency must be maintained.

The presentation of CoA later in life is usually as an incidental finding, although life-threatening complications such as intracranial bleed, aortic dissection, or infective endarteritis do occur. The more benign presentation usually involves a systolic murmur; absent or weak femoral pulses with brachiofemoral delay; upper extremity hypertension; hypertensive retinopathy; exercise intolerance; or leg fatigue or claudication. Electrocardiography may show LV hypertrophy, and the classic chest radiographic findings are the “3” sign and rib notching.

Valvar aortic stenosis

Congenital valvar AS is most frequently associated with a bicuspid AoV, which likely represents the most common CHD with an incidence of 0.4% to 2% in the general population. A true bicuspid AoV with only two leaflets is rare. Instead it usually results from fusion of two of the three leaflets or underdevelopment of one of the three commissures (known as a raphe), leading to the use of the term bicommissural AoV for these lesions. Fusion occurs most frequently at the intercoronary commissure between the right and left coronary leaflets (70%) ( Fig. 167.1 , A , and Video 167.1) followed by the commissure between the right and noncoronary leaflets (28%) (see Fig. 167.1 , B ) and the commissure between the left and noncoronary leaflets (rare). In adults, valvar AS appears to progress more rapidly in the setting of fusion of the intercoronary commissure, though studies in children have shown faster progression of AS and regurgitation as well as an earlier need for intervention when the right and noncoronary leaflets are fused. Common associations include CoA, subvalvar AS, VSD, coronary anomaly, Turner syndrome, and aortic dilation and aneurysm formation ^, (see Fig. 167.1 , C ).

A, Parasternal short-axis image of a bicommissural aortic valve with fusion of the intercoronary commissure. Notice the horizontal orientation of the aortic opening. B, Parasternal short-axis image of a bicommissural aortic valve with fusion of the commissure between the right and non-coronary leaflets. Notice the vertical orientation of the aortic opening. C, High parasternal long-axis image of ascending aortic dilation in association with a bicommissural aortic valve. D, Parasternal short-axis image in a neonate with valvar aortic stenosis and a unicommissural aortic valve where the only patent commissure is between the left and noncoronary leaflets.

Neonatal valvar AS most frequently presents as a unicuspid AoV with a small eccentric valvar orifice, usually at the commissure between the left and noncoronary leaflets (see Fig. 167.1 , D ), as well as thickened leaflets with poor mobility, a small aortic root and ascending aorta, and either a small, hypertrophied LV with endocardial fibroelastosis or a dilated LV with poor systolic function, mitral regurgitation, and left atrial dilation. Other AoV morphologic abnormalities associated with valvar AS include a dysplastic tricuspid AoV and a hypoplastic aortic “annulus.”

Echocardiographic evaluation of valvar AS must involve assessment of leaflet and commissural morphology, best seen in parasternal views. A bicuspid AoV with a horizontally oriented systolic opening in short-axis views is generally associated with fusion of the intercoronary commissure (see Fig. 167.1 , A ), whereas a more vertically oriented systolic opening is associated with fusion of the commissure between the right and noncoronary leaflets (see Fig. 167.1 , B ). Incomplete commissural separation can restrict lateral mobility of the leaflets, resulting in a systolic doming appearance in long-axis views. The degree of obstruction is assessed by measuring peak and mean gradients using continuous wave Doppler interrogation in apical, right sternal border, and suprasternal views, though one must be cognizant of the known discrepancies between the maximum instantaneous gradient measured by echocardiography and the peak-to-peak gradient measured by catheterization as well as the effects of pressure recovery. Although criteria for valvar AS severity have not been established for children, guidelines published for adults with valvar AS, including calculation of aortic valve area by the continuity equation, have been applied to the pediatric population. Three-dimensional echocardiography has also proven to be helpful in children as well as adults. ^, Other important components of the echocardiographic evaluation include assessment of the degree of LV hypertrophy, the presence of endocardial fibroelastosis, and the size of the ascending aorta (see Fig. 167.1 , C ).

An important early decision in the management of neonates with critical valvar AS involves the choice between biventricular repair and univentricular palliation, as many of these patients have borderline hypoplastic LVs. Several efforts have utilized multivariable analyses to identify the risk factors for mortality with either approach, and these risk factors have included aortic and mitral annular size, relative LV length, and endocardial fibroelastosis grade.

Aortic coarctation

CoA is typically juxtaductal in location, involving the aortic isthmus. The length of the narrowed segment may be discrete or long-segment. Narrowing or hypoplasia of the transverse arch is more commonly found in patients presenting as fetuses or early in childhood, whereas discrete narrowing with the presence of collaterals is more often seen in patients presenting later. The vast majority of patients with CoA are now diagnosed as infants. The diagnosis of CoA is 1.7 times more common in males, but CoA occurs in 12% to 17% of patients with Turner syndrome. In several large series of patients with CoA, 14% to 27% had significant AS or aortic regurgitation. Complications are common in patients following CoA repair, and age at repair appears to be a risk factor. Late cardiovascular complications include systemic hypertension, recoarctation, dissection, aneurysm, rupture, and early coronary artery disease.

The hallmark of CoA is luminal narrowing of the aorta due to a posterior “shelf” or a circumferential membrane. A helpful anatomic definition of narrowing is a diameter of the proximal transverse arch 60% or less of the ascending aorta diameter, distal transverse arch 50% or less, or isthmus 40% or less. Echocardiography is a useful diagnostic tool for CoA, but imaging of the aortic isthmus and proximal descending aorta is difficult in older children and adults ( Fig. 167.2 , A /Video 167.2, A ). In those cases, other imaging modalities such as magnetic resonance imaging ( Fig 167.2 , B /Video 167.2, B ) or computed tomography are indicated.

Goals of the echocardiographic examination include evaluation of aortic arch sidedness and branching pattern, severity and length of CoA, size of other aortic segments (including aneurysms), other left-sided structures (including AoV morphology), collaterals, LV size and function (including LV mass), and associated lesions. The arch is best visualized from suprasternal and high left sternal border windows, but it may be seen in neonates even from the subcostal window. Aortic branching is evaluated in suprasternal short-axis imaging, with a normal pattern visualized as a bifurcating first brachiocephalic artery to the right (opposite to the sidedness of the arch). Absence of normal bifurcation may raise the suspicion of an aberrant right subclavian artery. The region of the CoA and proximal descending aorta is sometimes better seen in a sagittal plane at the high left sternal border window using the main pulmonary artery as a “window” for imaging. A juxtaductal CoA can involve the origin of the left subclavian artery. If present, an aberrant subclavian artery may be above or below the site of CoA.

Doppler interrogation for the CoA gradient is best performed in the suprasternal view, occasionally with the transducer positioned toward the neck or right subclavicular region to align the ultrasound beam with the long axis of the descending aorta or aortic isthmus. The Doppler tracing of significant CoA shows a high-velocity systolic peak followed by gradual deceleration throughout diastole ( Fig. 167.3 , A ). Peak and mean gradients are measured, and in the setting of multiple levels of obstruction the gradient proximal to the CoA site (measured by pulsed wave Doppler) should be subtracted from the total gradient. An important aspect of echocardiographic screening for CoA is the Doppler pattern of the descending aorta at the level of the diaphragm, where a low-velocity signal with continuous antegrade diastolic flow may be seen (see Fig. 167.3 , B ).

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