1. (C) PW Doppler utilizes one crystal that both emits and receives the sound pulses. The maximal frequency shift that can be determined by PW Doppler is equal to one-half the PRF and is termed the Nyquist limit. This Nyquist limit can be extended by using lower frequency transducers. High PRF lacks range gating resulting in range ambiguity.

2. (A) The simplified Bernoulli equation ignores the components of flow acceleration and viscous friction. Doppler velocities across a patent ductus arteriosus or Blalock-Taussig shunt will likely be underestimated due to viscous friction in these tortuous connections and difficulties with proper ultrasound beam alignment. Multiple obstructions in series, such as multiple sites of LVOT obstruction (subvalvar, valvar, coarctation), will need to account for flow acceleration proximal to the distal site(s) of obstruction. Isolated valvar stenoses would be an appropriate use of the simplified Bernoulli equation.

3. (B) These Doppler patterns are consistent with impaired relaxation. Mitral inflow Doppler demonstrates an E:A ratio <1, while mitral annular tissue Doppler imaging also demonstrates a decreased early annular velocity and abnormal E′/A′ ratio <1. Pulmonary venous Doppler shows a systolic dominance and a prominent atrial reversal wave, consistent with grade 1 diastolic dysfunction (Figure 5.25).

4. (D) The pressure gradient can be predicted by using the “expanded” Bernoulli equation, P₁ – P₂ = 4(V₂² – V₁²), utilizing the Doppler velocities proximal and distal to the coarctation: 4 ([4.0]² – [2.0]²) = 48 mm Hg.

5. (E) The presence of holodiastolic flow reversal in the abdominal aorta is consistent with severe aortic regurgitation.

6. (C) Contrast agents are designed to pass through the pulmonary capillary bed to opacify the left heart structures. The typical size of these microspheres is 1 to 10 microns. The acoustic impedance of contrast agents is much lower than that of the blood pool. The contrast effect persists for 3 to 5 minutes with most contrast agents.

7. (D) Microbubbles created with agitated saline range in size from 10 to 100 microns and do not pass through the pulmonary capillary bed. These microbubbles opacify the right atrium and right ventricle but not left heart structures in the absence of an intracardiac or intrapulmonary shunt (video 5.4a). They can be helpful to identify an intracardiac right-to-left shunt that may be an etiology in stroke or unexplained cyanosis (video 5.4b). In the presence of an intrapulmonary shunt, the microbubbles typically appear in the left heart in three to five cardiac cycles compared to one to two cardiac cycles for an intracardiac shunt (video 5.4c). A negative bubble study does not definitively exclude the presence of an intermittent right-to-left shunt.

8. (D) The width of the regurgitant jet (vena contracta) and the ratio of the vena contracta dimension to the aortic annulus dimension are quantitative measures to grade aortic regurgitation. The degree of LV dilatation is a semiquantitative measure and is most consistent with the duration of aortic regurgitation in addition to its severity. The length of the regurgitant jet into the left ventricle is influenced by many factors in addition to regurgitant severity including LV end-diastolic pressure and eccentricity of the jet. The degree of Doppler flow reversal in the abdominal aorta is an excellent predictor of regurgitation degree as is the forward to reverse flow TVI ratio in the distal transverse aortic arch.

9. (A) The MPI is the ratio of the total time spent in isovolumic activity (isovolumic contraction and isovolumic relaxation times) divided by the time spent in ventricular ejection (Figure 5.26).

10. (D) The subcostal imaging window is optimal to demonstrate the atrial septum and any associated atrial septal defects that may be present. To visualize the atrial septum without potential drop-out, the imaging plane of sound should be perpendicular to the cardiac structure of interest. With respect to the atrial septum, the imaging plane that is optimally perpendicular is the subcostal four-chamber and sagittal views. Atrial septal defects can be demonstrated in other imaging windows including the parasternal short-axis, apical four-chamber, and high right parasternal views but care must be taken not to diagnose an atrial septal defect when the plane of sound is more parallel to the atrial septum creating the potential for false drop-out in the 2D image. The addition of color Doppler and spectral Doppler interrogation in these views will also facilitate the diagnosis of an atrial septal defect (Figure 5.27).

11. (A) Sinus venosus atrial septal defects are most commonly associated with anomalous connection of the right pulmonary veins. Either a single right upper pulmonary vein or the right upper and middle pulmonary veins insert anomalously to the superior vena cava or the SVC-right atrial junction. Sinus venosus defects are found most commonly in the superior portion of the atrial septum creating a “biatrial” insertion of the superior vena cava. These defects can also be located inferiorly near the entrance of the inferior vena cava into the right atrium.

12. (C) Constrictive pericarditis is characterized by increased respiratory variation in mitral inflow Doppler velocities by >25%. Transmitral Doppler often demonstrates an increased E:A ratio and a shortened E-wave deceleration time. Lateral mitral tissue Doppler velocities are usually normal. Hepatic venous Doppler will demonstrate increased atrial systolic flow reversals during expiration.

13. (C) Echocardiographic hallmarks of restrictive LV physiology in adults include an increased mitral inflow Doppler E:A ratio >2.0, shortened mitral E-wave deceleration time <160 ms, decreased lateral mitral E_a velocity, and an increased E/E′ ratio >15. Pulmonary venous Doppler demonstrates decreased systolic to diastolic pulmonary venous filling wave ratio with significantly increased atrial reversal wave velocity and duration.

14. (D) The newborn male has D-transposition of the great arteries (D-TGA) as evident from the videos 5.1a,b demonstrating pulmonary artery arising from the left ventricle and aorta arising from the right ventricle. Neonates with D-TGA can have a variable degree of desaturation depending primarily on the atrial and also on ventricular level shunts. The initial blood gas in the patient revealed a low arterial PaO₂ of 29 mm Hg in addition to low oxygen saturations, which suggest restricted atrial level shunt. All of these will be prominent indications for balloon atrial septostomy as the next best step in the management of the current patient.

15. (D) Anatomic hallmarks of AVSD include a cleft in the anterior leaflet of the left atrioventricular valve, lateral rotation of the left ventricular papillary muscles, and attachments of the left and right atrioventricular valves at the same level at the cardiac crux. In addition, due to the absence of the atrioventricular septum in these defects, the left ventricular inflow is shortened and the left ventricular outflow is elongated (“goose-neck deformity”) creating a ratio of LV inlet to LV outlet ratio <1. Owing to the presence of a common atrioventricular valve, the aortic valve is no longer “wedged” between the tricuspid and the mitral valves and is pushed anteriorly (“sprung”).

16. (B) M-mode has excellent temporal resolution and a high fixed PRF. The x-axis represents time while the y-axis represents distance from the transducer. M-mode utilizes a single imaging crystal.

17. (A) Spatial resolution is defined as the smallest distance between two points that are distinguishable from one another. Axial resolution is the ability to differentiate points along the ultrasound beam and is equal to its wave-length. Lateral resolution is the ability to resolve points perpendicular to the ultrasound beam and is dependent on beam width, with the best resolution found where the beam is the narrowest. Axial resolution is better than lateral resolution.

18. (A) Doppler velocity is calculated as follows: V = [c(f_d)]/[2f_o cos θ]. The speed of sound (c) and the transmitted ultrasound frequency (f_o) are constant while the frequency shift (f_d) can be measured very accurately. Therefore, the main source of error in velocity calculation is the angle of incidence (θ) between the ultrasound beam and the moving structure or blood. When the angle of incidence is <20 degrees, the Doppler velocity is not significantly underestimated (Figure 5.28).

19. (B) CW Doppler utilizes two crystals, one that is continuously transmitting and one that is continuously receiving, making the sampling rate infinite so that there is no limit to the detection of the maximal frequency shift. A disadvantage is that there is no range gating resulting in lack of range resolution (the maximal Doppler velocity can be anywhere along the ultrasound beam path). Both CW and PW Dopplers are equally dependent on the angle of incidence for accurate velocity determination (Figure 5.29).

20. (C) PW Doppler utilizes one crystal that intermittently transmits and receives. The time between transmission and reception allows the determination of the depth of the signal providing excellent range resolution. However, the maximal detectable frequency shift is limited resulting in a lower Nyquist limit than CW Doppler. Spectral Doppler has a higher PRF than color Doppler. PRF varies with the depth of the sample volume with PW Doppler, with a higher PRF with more shallow sample volumes.

21. (A) The Nyquist limit is the maximal frequency shift detectable by PW Doppler and is equal to one-half of the PRF. The Nyquist limit is lower with PW Doppler and is increased with lower frequency transducers and at shallow depths of interrogation.

22. (A) Color Doppler utilizes multiple sampling sites along multiple ultrasound beams to generate frequency shifts that are converted into a digital format and autocorrelated into a color scheme. Color Doppler is a mean velocity of blood flow with the intensity of color representing mean Doppler flow velocities. The Nyquist limit is lower with color Doppler compared to spectral Doppler. Color Doppler is superimposed on 2D images resulting in less resolution.

23. (D) Subpulmonary VSDs are located adjacent to the pulmonary valve and aortic valve. These VSDs have been termed subpulmonary, supracristal, or doubly committed defects. These defects can be best demonstrated in the parasternal short-axis scan plane but can also be demonstrated from the subcostal and apical windows with appropriate angulation into the right ventricular outflow tract.

24. (C) Coronary artery anomalies have been reported in approximately up to 10% of the patients with TOF. It is critical to delineate the coronary artery anatomy preoperatively as they can potentially affect the surgical management. The most common coronary artery anomaly is origin of left anterior descending (LAD) from the right coronary artery (RCA) or accessory LAD from the RCA. A single coronary artery (more often from the left coronary sinus) is the next most frequent variant and occurs in up to 1% of patients. Although a prominent conal branch can be commonly seen in many patients with significant right ventricular hypertrophy, it is not considered as anomalous anatomy.

25. (C) Large ventricular septal defects result in equalization of right and left ventricular pressures as well as elevated pulmonary arterial pressure. Left-to-right shunting at ventricular level results in a substantial increase in pulmonary blood flow with left atrial and left ventricular volume overload. Overall systemic blood flow is not significantly increased in this setting.

26. (A) (Figure 5.30) The best morphologic hallmarks of the right atrium are the broad-based right atrial appendage and the connections of the inferior vena cava and coronary sinus. Superior vena caval connection(s) have significant anatomic variability. Atrioventricular relationships can also vary and are not hallmarks of right atrial morphology. The valve of the fossa ovalis is septum primum and is a left atrial structure. The atrioventricular valve is a hallmark of ventricular morphology, with the morphologic tricuspid valve being the anatomic hallmark of the right ventricle.

27. (B) The best imaging plane to define the entire atrial septum is the subcostal imaging plane because it is perpendicular to this anatomic structure. (videos 5.5a,b) False drop-out can occur in imaging planes that are more parallel to the atrial septum.

28. (B) The best anatomic hallmark of the morphologic right ventricle is the connection of the tricuspid valve with a more apical insertion at the cardiac crux compared to the morphologic mitral valve. The tricuspid valve is “septophilic” with attachments to the ventricular septum. The right ventricle is more crescent in shape with prominent trabeculations (Figure 5.31).

29. (D) A higher insertion of the morphologic mitral valve at the cardiac crux and lack of atrioventricular valve chordal attachments to the ventricular septum (“septophobic”) are excellent anatomic hallmarks of the morphologic LV. The LV is elliptical in shape with fine trabeculations, mainly toward the cardiac apex (Figure 5.31).

30. (A) Utilizing the modified Bernoulli equation to obtain the peak instantaneous gradient across the pulmonary valve, 4 × (velocity)², then 4 × (4.0)² = 64 mm Hg.

31. (B) The most common type of subaortic stenosis is related to a discrete membrane proximal to the aortic valve within the LVOT (Fig. 5.32) (videos 5.6a,b). This membrane is most often circumferential and can be adherent to both the aortic valve and the anterior leaflet of the mitral valve. LVOT obstruction in the setting of hypertrophic cardiomyopathy (HCM) is often related to asymmetric septal hypertrophy in combination with systolic anterior motion of the mitral valve chordal and leaflet tissue. Anomalous mitral chordal insertions within the LVOT can be isolated or found in association with congenital heart disease and may result in obstruction but are not as common as discrete membranes.

32. (A) Bicuspid aortic valve is the most commonly associated cardiac finding in patients with simple coarctation, with some studies showing as high as an 80% occurrence in patients with coarctation. Atrial and ventricular septal defects are also common in patients with coarctation. Pulmonary valve stenosis and coronary arterial anomalies are much less frequent in this cohort.

33. (B) Newborn baby is demonstrating persistent pulmonary hypertension evident by the bidirectional flow at the level of patent ductus arteriosus (PDA) demonstrated by the spectral Doppler pattern in the PDA. There is >10% split between pre- and postductal oxygen saturation with lower postductal saturation due to the right-to-left shunting at the level of PDA. However, in patients with transposition of great arteries and coarctation of the aorta, a reverse differential cyanosis is seen with lower preductal and higher postductal oxygen saturation due to the shunting of oxygenated blood from the pulmonary artery to the aorta.

34. (C) Cardiac tamponade occurs when increasing fluid in the pericardial space causes a rise in intrapericardial pressure (typically greater than intracardiac pressure) compromising systemic venous return to the right atrium. Diastolic right atrial and right ventricular wall collapse occurs when intrapericardial pressure exceeds intracardiac pressure, with collapse of the right ventricle more sensitive to identify tamponade physiology. Pulsed-wave Doppler is more sensitive to identify cardiac tamponade with respiratory changes in Doppler flow across the tricuspid valve (>30%) and mitral valve (>25%) being most characteristic due to ventricular interdependence. While the overall size of the pericardial effusion is important, how quickly the fluid accumulates has more of an effect on intrapericardial pressure due to the relative compliance of the pericardium in the acute and chronic settings.

35. (E) The relationship between velocity of circumferential fiber shortening and end-systolic wall stress is independent of heart rate and preload and incorporates afterload making it a quantitative measure of ventricular contractility. Ejection fraction, shortening fraction, and the myocardial performance index are all significantly impacted by both preload and afterload.

36. (D) Patients with tricuspid atresia can develop restriction at the level of atrial septum with varying clinical presentation ranging from asymptomatic to severe right-sided congestion or poor perfusion. Elevated right atrial pressure, hepatomegaly, peripheral edema, hypotension, and poor perfusion may be some of the presenting clinical symptoms. Patients with atrial septal aneurysm on their initial echocardiogram have been shown to be at increased risk for developing atrial septal restrictions. On the other hand, restriction of the ventricular septal defect or increase in the pulmonary/subpulmonary obstruction generally manifest with declining oxygen saturations as the initial presentation without evidence of right-sided congestion.

37. (B) The presence of holodiastolic Doppler flow reversal is consistent with a significant run-off from the descending aorta including a large patent ductus arteriosus, severe aortic valve regurgitation, systemic-to-pulmonary artery shunts, and large arteriovenous fistula.

38. (C) The most common VSD associated with coarctation is a perimembranous defect. While less common, a posterior malalignment VSD often results in severe coarctation or interruption of the aortic arch. Muscular VSD as well as inlet VSD can also occur in the setting of coarctation, in particular with an unbalanced RV-dominant AVSD.

39. (A) The systolic jet in patients with supravalvar aortic stenosis propagates further than the jet originating with aortic valvar stenosis and has a tendency to be entrained along the aortic wall thereby transferring its kinetic energy into the right innominate artery. This physical principle, termed the Coanda effect, often is expressed clinically in these patients by marked discrepancy in upper arm blood pressures, with the right arm pressure higher than the left arm blood pressure.

40. (B) In the simplified Bernoulli equation, convective acceleration is calculated while flow acceleration and viscous friction are ignored. To accurately utilize the simplified equation, the proximal Doppler velocity must be negligible (Figure 5.33).

41. (C) An overriding atrioventricular valve empties into two ventricles. It is committed to the ventricle to which >50% of its orifice is directed (Figure 5.34). This connection is always associated with a malalignment VSD. Valves that override can also straddle by having chordal attachments to the contralateral ventricle (Figure 5.34).

42. (E) A straddling atrioventricular valve has anomalous chordal insertions or papillary muscles in the contralateral ventricle. Straddling and override often coexist. Straddling is associated with the presence of a VSD but does not require a malalignment type of defect. Semilunar valves do not have chordae or papillary muscles so they do not straddle. Straddling is not a common feature of tetralogy of Fallot.

43. (C) Interruption of the intrahepatic portion of the IVC with azygos vein continuation to the superior vena cava is a common feature of polysplenia syndrome (left atrial isomerism). The abdominal situs is variable and can be ambiguous, inversus, or solitus. The spleens are usually multiple and are characteristically located on the same side. A single gallbladder is most typical but biliary atresia can and does occur.

44. (E) The patient has a complete vascular ring consisting of right-sided aortic arch and aberrant left subclavian artery which can lead to the compression of the esophagus or trachea. Division of the ligamentum arteriosum can release the compression on the surrounding structures in most cases, while some patients may require translocation of the aberrant subclavian artery traversing behind the esophagus or trachea.

45. (C) Tricuspid atresia is an example of a single-inlet atrioventricular valve connection (Figure 5.35).

46. (E) Atrial myxoma is the second most common form of cardiac mass in children, second to rhabdomyomas. The most common location of atrial myxomas is left atrium in 75% of the cases. They are commonly friable, pedunculated, red lobular tumors typically attached to the atrial septum. Myxomas can be associated with the triad of (a) valvular obstruction, (b) embolic events, and (c) systemic illness. Once a diagnosis of atrial myxoma has been made on imaging studies, prompt resection is indicated due to the risk of embolization or cardiovascular complications, including sudden death.

47. (B) When a persistent left superior vena cava drains to the coronary sinus, the size of the coronary sinus is inversely proportional to the size of the bridging innominate vein. When the coronary sinus is severely dilated, the innominate vein is most commonly very small or absent. When the inferior vena cava is interrupted, venous return is directed from the azygos vein to the superior vena cava. Interruption of the IVC is more common in polysplenia syndrome versus asplenia syndrome. Superior vena caval connections are variable and are not an anatomic hallmark of the morphologic right atrium. The left pulmonary veins more commonly merge than the right veins as they connect to the left atrium.

48. (D) While all these are features that distinguish the morphologic tricuspid valve from the mitral valve, the most reliable anatomic hallmark is the level of attachment of the atrioventricular valve at the cardiac crux. The atrioventricular valves are invariably associated with their appropriate morphologic ventricle (tricuspid valve with the right ventricle and mitral valve with the left ventricle) and are the best marker for atrioventricular connection and ventricular morphology.

49. (C) Constrictive pericarditis is caused by thickened, inflamed, or calcific pericardium that limits the diastolic filling of the heart causing heart failure. Risk factors for constriction include previous cardiac surgery, recurrent pericarditis, episodes of pericardial effusion, and radiation therapy. Due to the fixed cardiac volume within the thickened pericardium, diastolic filling of right and left ventricles rely on each other. On echocardiography, it is characterized by increased respiratory variation in mitral inflow Doppler velocities by >25% and increased diastolic flow reversal with expiration in the hepatic vein. Other features of constriction may include an increased E:A ratio and a shortened E-wave deceleration time.

50. (C) Subcostal images demonstrate a sinus venosus atrial septal defect with partial anomalous pulmonary venous connection to the superior vena cava. The defect is located in the superior/posterior portion of the atrial septum adjacent to the superior vena cava. The right upper and middle pulmonary veins are often anomalous and most commonly connect to the superior vena cava.