Congenital Cardiac Anomalies

Question 1

What is the incidence of congenital heart disease?

Answer 1

There are approximately 9 new cases of congenital heart disease per 1000 live
births annually and this number is relatively constant around the world.

Question 2

When does the heart develop?

Answer 2

Cells in the lateral mesoderm begin to differentiate into pre-cardiac cells early in the 3rd week of gestation. After a complex process of folding and spiraling, cardiac development is essentially complete by about 7 weeks gestation.

Question 3

What are the 3 physiologic fetal shunts?

Answer 3

The ductus venosus, foramen ovale and ductus arteriosus are the 3 fetal shunts that help facilitate the streaming of oxygenated placental blood to the cerebral and cor- onary circulation and deoxygenated blood to the lower body, viscera and placenta for re-oxygenation.

Question 4

What factors affect ductal (arteriosus) patency?

Answer 4

In the fetus, ductal patency is maintained by low oxygen saturation and high levels of circulating prostaglandins.

After birth, the rise in oxygen saturation inhibits prostaglandin synthase resulting in a decreased level of prostaglandin.

COX-2 inhibition (NSAIDs) can cause ductal constriction.

Question 5

When is ligation of a patent ductus arteriosus (PDA) indicated in pre-term infants?

Answer 5

For pre-term infants, closure is indicated in a hemodynamically significant PDA.

Hemodynamic significance is demonstrated by excessive left to right ductal flow resulting in too much blood flow to the lungs and too little blood flow to the body.

Unless contraindicated, NSAID trials are attempted prior to surgical ligation.

Question 6

What are important anatomic landmarks to identify a ductus arteriosus?

Answer 6

After left posterolateral thoracotomy, the 3rd or 4th interspace is entered and the lung is retracted anteriorly and inferiorly. Once the phrenic and left recurrent laryngeal nerves are identified, enough pleura is opened to clearly identify the left subclavian artery, distal aortic arch, descending aorta and PDA. The PDA may be safely ligated about 1 to 2 mm from its aortic end at that time [3].

Question 7

What hemodynamic changes should occur after a PDA is ligated?

Answer 7

A rise in systemic blood pressure—diastolic greater than systolic—should be seen [4]. 8.

Question 8

What are the commonly seen and described vascular rings?

Answer 8

The complete vascular rings are: double aortic arch, right aortic arch with aberrant left subclavian artery, right aortic arch with mirror image branching and ligamentum arteriosum arising from descending aorta.

Incomplete rings are: left pulmonary artery sling (left pulmonary artery arising from right pulmonary artery), innominate artery compression syndrome and left aortic arch with aberrant right subclavian artery [3].

Question 9

What are the cyanotic heart lesions?

Answer 9

The classic cyanotic heart lesions all start with the letter “T.” Tetralogy of Fallot, truncus arteriosus, transposition of the great arteries, total anomalous pulmonary venous return and tricuspid valve atresia can all cause cyanosis.

Question 10

When and why can total anomalous pulmonary venous return (TAPVR)
be a true congenital cardiac urgency?

Answer 10

TAPVR describes anomalous drainage of the pulmonary veins into the systemic venous atrium.

This can occur directly to the right atrium, via a remnant of the cardinal vein system (supra-cardiac), via a remnant of the umbilico-vitelline system (infra-cardiac) or as a mixture of these types.

Due to drainage of all blood to the right atrium, an atrial level shunt must be present.

If this shunt is restrictive to flow at the level of the accessory vein—profound respiratory distress and cardiogenic shock will result shortly after birth.

This is considered obstructive TAPVR and is an indication for emergent repair or extra-corporeal support if the diagnosis is not clear [1].

Question 11

Why are ventricular septal defects (VSDs) approached with different treatment algorithms?

Answer 11

A VSD is a defect in the interventricular septum that results in blood flow from the left ventricle to the right ventricle and can result in too much blood flow to the lungs (heart failure).

Many VSDs, both muscular and peri-membranous, have potential to close on their own.

Therefore, if a VSD is small enough (restrictive to flow) that a patient can be medically managed (diuretics) and grow, surgery can be deferred.

Larger VSDs or those with associated defects often need to be closed in infancy.

Question 12

Where is the heart’s conduction tissue and when is it in jeopardy?

Answer 12

The sino-atrial node is located on the atrial side of the junction of the right atrium and superior vena cava on the epicardial surface of the heart.

It should be considered with any right atrial or superior vena cava manipulation.

The AV node lies within the triangle of Koch—bounded by the coronary sinus, the tendon of Tedaro and the anteroseptal commissure of the tricuspid valve.

It is at risk with operations near the crux of the heart such as a VSD or atrioventricular septal defect (AVSD) closure.

Question 13

What is a “tet spell?”

Answer 13

Tetralogy of Fallot (TOF) is a common cardiac diagnosis caused by anterior malalignment of the conal septum and resulting in 4 defects—VSD, overriding aorta, pulmonary stenosis and right ventricular hypertrophy (RVH).

As the RVH worsens, more blood is forced away from the lungs and into the aorta—espe- cially with a catecholamine surge – resulting in a cyanotic spell.

Anything that increases systemic vascular resistance (alpha agonists) and decreases the cat- echolamine response (soothing, narcotic, beta blocker) will help mitigate the cyanosis [1].

Question 14

Which heart defect is most likely in a child born with trisomy 21 and how
likely?

Answer 14

Approximately 40% of patients with trisomy 21 have an AVSD. Conversely, approximately 75–80% of patients with AVSD have trisomy 21 [1].

Question 15

What does “unbalanced” AVSD mean?

Answer 15

Some patients with an AVSD have a common atrioventricular valve that does not sit above 2 equally sized ventricles.

Some have severe enough ventricular hypoplasia that the heart cannot be divided into 2 systems and a single ventricle path- way is necessary.

Question 16

When is a pulmonary artery band (PAB) needed and what are the pitfalls of placing one?

Answer 16

Pulmonary artery banding is a palliative procedure used to limit excessive pul- monary blood flow from a large left-to-right shunt and ameliorate heart failure.

In contemporary times, this is mostly limited to single ventricle patients with excessive pulmonary blood flow and occasional scenarios where complete repair of a 2 ventricle patient is deferred.

Achieving appropriate band tightness can be difficult as there are numerous and dynamic factors affecting pulmonary blood flow and pulmonary vascular resistance.

The band being placed too distally or migrating distally can cause right pulmonary artery impingement as well.

Question 17

What is a Blalock Taussig (BT) Shunt and when is one needed?

Answer 17

The modern version of the BT shunt is anastomosing a polytetrafluoroethylene (PTFE) tube graft from the right subclavian artery to the right pulmonary artery.

This is performed to augment pulmonary blood flow and is frequently used as the initial palliation or part of the initial palliation in cyanotic single ventricle patients, but is also occasionally used to palliate 2 ventricle patients needing additional pulmonary blood flow if a complete repair is deferred.

Question 18

What is the Norwood Procedure?

Answer 18

The Norwood procedure is the complex operation performed for hypoplastic left heart syndrome. It consists of: anastomosing the aorta to the pulmonary artery (Damus-Kaye-Stansel), enlarging the aortic arch, atrial septectomy and either a systemic to pulmonary artery (BT) shunt or right ventricle to pulmonary artery (Sano) shunt.

Question 19

What are the 2nd and 3rd stages of the single ventricle pathway?

Answer 19

As an infant’s pulmonary vascular resistance falls after the first few months of life, their physiology gradually becomes better suited to tolerate the continuous single ventricle circuit of a Fontan.

The 2nd stage (in some cases actually referred to as hemi-Fontan) is a step toward the Fontan and is typically done between 3 and 6 months of age.

Most centers perform a bidirectional Glenn procedure, which is anastomosing the superior vena cava to the right pulmonary artery and removing the initial palliative shunt.

The Fontan completion is performed at about 2–5 years of age.

It consists of directing the inferior vena cava blood to the pulmonary artery via a tunnel or graft.

Upon completion, all the blood returning from the body is passively directed to the lungs.

Question 20

What are some known long-term complications of Fontan circulation?

Answer 20

Among other things, plastic bronchitis and protein-losing enteropathy, occurring in up to 14% and 13% respectively, are both long-term complications of Fontan that carry a poor prognosis [1].

Question 21

A 2-weeks-old male patient is brought to the emergency department with respiratory distress. He is not gaining weight.
His clinical examination shows stridor along with increased intercan-thal distance and short nasal bridge. His oxygen saturation is 97% in the room air. His chest x-ray suggests a narrowing of the airways. His echocardiography is performed, and it reveals two transverse aortic arches. What is the most common genetic syndrome associated with this condition?
Choices:
1. Noonan syndrome
2. Trisomy 13
3. Angelman syndrome
4. 22q11 deletion

Answer 21

Answer: 4-22g11 deletion
Explanations:
• This is a classical picture of the double aortic arch (DAA), as it presents in the earlier infancy.
• The clinical findings seen in DAA include an infant with stri-dor, dyspnea, failure to thrive, and choking episodes with feeding.
Examination in around 30% of the infants can show murmur or cyanosis.
• Chest x-ray is usually performed showing the narrow airways and dominant arch, which can be confirmed using MRI. Echocardiography can also support the diagnosis.
• Double aortic arch is usually associated with 22q11 deletion, sometimes it has been shown to be associated with trisomy 21 and 18.
Noonan syndrome is mostly associated with pulmonary valvular stenosis and atrial septal defects.

StatPearls

Question 22

A 2-year-old girl is brought to the clinic with abnormal facies characterized by a prominent nose, notched nostrils, and small chin. She also has a history of a cardiac ventricular septal defect.
The oral cavity exam reveals an overt cleft palate. Which of the following is the most appropriate imaging study to be ordered before attempting a cleft palate repair in this patient?
Choices:
1. CT angiography
2. X-ray head
3. Bronchoscopy
4. Chest x-ray

Answer 22

Answer: 1-CT angiography
Explanations:
• The patient demonstrates velocardiofacial (VCF) or Shprintzen syn-drome, an autosomal dominant condition characterized by cleft palate, cardiac anomalies, distinct facial features, and learning dis-abilities. While patients with VCF syndrome benefit from cleft palate repair, it is essential to perform imaging studies to verify the location of the internal carotid artery, as it may be displaced and situated more medially. This is particularly important in patients who may require a posterior pharyngeal flap in order to prevent a major vessel injury.
•CT angiography would be the only imaging modality able to confirm the anatomical location of the internal carotid artery.
• An x-ray head and chest x-ray are imaging studies that would not demonstrate the location of the internal carotid artery.
• Bronchoscopy is a useful exam to assess the lower airways.

StatPearls

Question 23

The most common primary cardiac tumour in children is:

A fibroma
B angiosarcoma
C rhabdomyoma
D teratoma
E myxoma.

Answer 23

C

Cardiac tumours are classified as primary (arising from the heart, more than 90% of which are benign) or secondary (representing metastases, which are uniformly malignant).

most cardiac tumours in children and adults represent metastatic disease. In children, these are secondary to non-Hodgkin’s lymphoma, leukaemia and neuroblastoma.

The most common primary cardiac tumour in children is rhabdomyoma, accounting for 50%–80% of all paediatric primary cardiac tumours.

other benign primary cardiac tumours vary according to age: in neonates and infants, fibroma and intrapericardial teratoma may occur, while in older children and adolescents, myxoma and fibroma are seen.

Rhabdomyomas are multiple, well-circumscribed, white, intracavitary or intramural masses that may occur anywhere in the heart.

most are diagnosed in the newborn period and may present with respiratory distress or heart failure, especially if large.

Tuberous sclerosis, an autosomal dominant mutation with variable expressivity, is a common association, with approximately 50% of patients with tuberous sclerosis having rhabdomyomas.

Approximately 30% of rhabdomyomas will regress spontaneously.

Rhabdomyosarcoma is the most common primary malignant cardiac tumour in children whereas angiosarcoma is the most common primary malignant cardiac tumour in adults; both portend a poor prognosis.

myxomas, arising from the interatrial septum, are the most common primary benign cardiac tumours in adults, usually diagnosed in the third to sixth decade of life.

Treatment is by surgical excision with reconstruction of the interatrial septum.

Fibromas represent the second most common primary benign cardiac tumour in children, and present usually as solitary large white non-encapsulated tumours in the left ventricular septum or free wall.

Presentations include left ventricular outflow tract obstruction and ventricular tachyarrhythmias.

Treatment is by surgical enucleation on cardiopulmonary bypass.

Intrapericardial teratomas are solitary, encapsulated tumours that are attached to the base of the heart. As with other teratomas, all three embryonic germ cell layers may be present. Treatment is by surgical excision.

SPSE 1

Question 24

All of the following may be found in scimitar syndrome except:

A dextrocardia
B haemoptysis
C aortopulmonary collateral artery
D bronchopulmonary sequestration
E ventricular septal defect.

Answer 24

E

Scimitar syndrome is a form of partial anomalous pulmonary venous return where the right pulmonary veins drain into the inferior vena cava, with subsequent drainage into the right atrium.

The left pulmonary veins drain normally into the left atrium.

There is often an associated atrial septal defect (ASD) that is low in the interatrial septum, close to the orifice of the inferior vena cava.

The chest radiograph in the anteroposterior projection shows the scimitar sign, which is a crescent-like shadow in the right lower lung field, parallel to and distinct from the right heart border. This extra shadow is similar to a scimitar, which is a curved Turkish sword.

Right pulmonary artery hypoplasia may be present, as well as right lung hypoplasia. As a result, the heart may be shifted to the right; cases of mesocardia (midline heart) or dextrocardia (cardiac apex pointing to the right) have also been described.

Pulmonary parenchymal abnormalities include sequestration, with an anomalous systemic arterial blood supply, usually from the descending thoracic aorta to the sequestered lung.

A ventricular septal defect is not associated with this defect, whereas an ASD is often found.

If no ASD is present, those patients typically present later in life, often in adulthood, with right atrial enlargement and right ventricular volume overload.

An ASD results in an earlier presentation because of the increased right atrial and right ventricular volume overload from left-to-right shunting across the interatrial septum, in addition to the anomalous drainage of the right pulmonary veins into the right atrium. This results in exercise intolerance and palpitations from atrial tachyarrhythmias, although a number of patients may be asymptomatic.

Treatment is by rerouting the anomalous right pulmonary veins into the left atrium, either through a baffle across the ASD, or by direct anastomosis of the pulmonary veins to the left atrium.

SPSE 1

Question 25

A child was a restrained passenger in a high-speed head-on motor vehicle collision. Of the following injuries after blunt cardiac trauma, which is the least likely to occur? A ASD B cardiac free-wall rupture C coronary artery thrombosis D ventricular septal defect E myocardial contusion

Answer 25

A Cardiac trauma is classified as blunt or penetrating, with most penetrating cardiac trauma resulting in death at the scene. Blunt cardiac trauma is most often due to high-speed motor vehicle collisions, usually from impact of the chest and sternum against the steering wheel or the dashboard. other causes include direct blows to the chest from an object, a fall or a kick. Although most patients are asymptomatic and free of injury, blunt cardiac trauma may be life-threatening. Clinical presentations include free-wall rupture of the atria or ventricles, coronary artery trauma with thrombosis, tachyarrhythmias, rupture of the chordae tendinae or papillary muscles, pericardial rupture with cardiac herniation, pericardial effusions and aortic transection, typically at the ligamentum arteriosum in the proximal descending thoracic aorta from a sudden deceleration injury. of those with blunt cardiac injuries who survive the injury to present in the emergency room, myocardial contusion is the most common presentation. This may result in cardiac enzyme elevations, premature ventricular contractions and arrhythmias on electrocardiography, and regional wall-motion abnormalities on echocardiography. Pericardial effusions may be present, and delayed myocardial rupture may occur. of the choices presented, all involve the ventricular myocardium except ASDs, which are not recognised as common sequelae of blunt cardiac trauma. SPSE 1

Question 26

The vascular structure that has the highest oxygen saturation in the fetal circulation is: A aorta B umbilical vein C ductus arteriosus D umbilical artery E ductus venosus.

Answer 26

B The fetal circulation is characterised by several shunts: the ductus venosus in the liver that shunts blood from the umbilical vein into the inferior vena cava, the foramen ovale that shunts blood from the right atrium to the left atrium, and the ductus arteriosus that shunts blood from the right ventricle into the descending thoracic aorta. Fetal haemoglobin binds oxygen more avidly than mature haemoglobin, and holds onto oxygen more strongly as well. As a result, the arterial oxygen saturation in the fetal aorta is only 60%–65%. Blood travels from the fetal descending thoracic aorta through the right and left fetal common iliac arteries, into the right and left fetal internal iliac arteries, then into the right and left umbilical arteries into the placenta, which has low vascular resistance. After oxygenation, the blood travels from the placenta into the fetal umbilical vein, a solitary structure that drains into the ductus venosus in the liver. Blood from the ductus venosus drains into the inferior vena cava then the right atrium. Streaming within the right atrium directs the inferior vena cava blood towards the foramen ovale and into the left atrium, thence into the left ventricle and the ascending aorta. This ensures that the fetal brain and heart receive blood with the highest possible oxygen saturation. The blood from the superior vena cava will enter the right atrium and preferentially stream into the right ventricle, then into the main pulmonary artery. Fetal pulmonary vascular resistance is high because of the collapse of the fetal lungs and the muscularisation of the pulmonary arterioles. As a result, most of the blood in the main pulmonary artery will drain into the descending thoracic aorta via the ductus arteriosus. The blood in the transverse aortic arch will mix with the blood from the ductus arteriosus and return to the placenta for oxygenation. Immediately following birth, the paired umbilical arteries close first, allowing a brief period of autotransfusion from the placenta into the umbilical vein. Within a week of birth, the umbilical vein will become a fibrous cord, knows as the round ligament of the liver. This passes from the umbilicus to the transverse hepatic fissure, where it joins the ligamentum venosum (remnant of the ductus venosus) to separate the liver into right and left hepatic lobes. SPSE 1

Question 27

The most common congenital cardiac anomaly is: A ASD B bicuspid aortic valve C ventricular septal defect D D-transposition of the great arteries E tetralogy of Fallot.

Answer 27

B The most common cyanotic congenital heart disease lesion in the neonatal period is D-transposition of the great arteries, where the aorta and main pulmonary artery are transposed, with the aorta connecting to the right ventricle, and the main pulmonary artery connecting to the left ventricle. The most common cyanotic congenital heart disease lesion beyond the neonatal period is tetralogy of Fallot, manifested by hypoplasia of the outflow of the right ventricle with the presence of a ventricular septal defect below the aortic valve. Ventricular septal defects are common in congenital heart disease, and are divided into four types: muscular, perimembranous, inlet and conal septal types. ASDs are also common, and are also of four types: secundum defects, primum defects, coronary sinus septal defects and sinus venosus defects. A bicuspid aortic valve is by far the most common congenital cardiac anomaly, occurring in 1%–2% of the population, more commonly in males. While fusion of any of the three commissures of the aortic valve is possible, the most common fusion site is between the right and left sinuses of Valsalva. At birth, most patients with bicuspid aortic valves are asymptomatic, although some will present with critical neonatal aortic stenosis requiring intervention. A bicuspid aortic valve is associated with aortic coarctation, which is a narrowing of the aorta at the insertion of the ductus arteriosus in the proximal descending thoracic aorta. In adulthood, bicuspid aortic valves predispose to the development of aortic stenosis, with some patients requiring aortic valve replacement. In addition, there is an association between bicuspid aortic valves and the development of ascending aortic aneurysms and aortic dissections. SPSE 1

Question 28

Which statement regarding the aorta and aortic arch is correct? A In a left aortic arch, the aortic isthmus lies proximal to the left subclavian artery. B The most common aortic arch anomaly is a right aortic arch with an aberrant left subclavian artery. C The ascending aorta normally arises posterior and to the right of the main pulmonary artery. D Patients with a double aortic arch become symptomatic late in infancy or young adulthood. E Truncus arteriosus is commonly associated with an interrupted aortic arch.

Answer 28

C The aortic arch is divided into three segments. In a left aortic arch, the proximal arch is the segment between the right innominate (brachiocephalic) artery and the left common carotid artery; the distal arch is the segment between the left common carotid artery and the left subclavian artery; the aortic isthmus is the segment between the left subclavian artery and the patent ductus arteriosus (PDA) (or ligamentum arteriosum). The most common aortic arch anomaly is a right aortic arch with mirror-image branching, where the aortic arch vessels are a mirror image of the left aortic arch. The first branch off a right aortic arch with mirror-image branching is the left innominate (brachiocephalic) artery, the second branch is the right common carotid artery, and the third branch is the right subclavian artery. The descending thoracic aorta in this setting descends in the right chest, reflecting a mirror image of what takes place in a normal left aortic arch, where the descending thoracic aorta descends in the left chest. The vast majority of those patients (approximately 90%) have associated congenital heart disease. Patients with vascular rings most commonly have a double aortic arch, where there are two aortic arches. Typically, the left aortic arch in a double aortic arch is the smaller of the two arches, and may even be atretic, represented by a fibrous cord. Since the constriction of the trachea and oesophagus is complete (360 degrees), patients with a double aortic arch present early in infancy, often within the neonatal period. Another common vascular ring is the right aortic arch with an aberrant left subclavian artery and a left ligamentum arteriosum, the latter two structures arise from a diverticulum of Kommerell. In patients with truncus arteriosus, there is a common arterial trunk arising from the ventricular mass. The pulmonary arteries arise off this common trunk, which continues as the ascending aorta. There is no pulmonary valve. In truncus arteriosus, the aortic arch is left-sided in 65%, and right-sided in 35%. The aortic arch is interrupted in only 10%–15% of patients with truncus arteriosus. In normal cardiac development, the ascending aorta arises posterior and to the right of the pulmonary artery, with the ascending aorta arising from the left ventricle, and the main pulmonary artery arising from the right ventricle. In D-transposition of the great arteries, there is ventriculoarterial discordance, meaning that the ascending aorta arises from the right ventricle, and the main pulmonary artery arises from the left ventricle. In most cases of D-transposition of the great arteries, the aorta arises anterior and to the right of the main pulmonary artery. SPSE 1

Question 29

PDA in premature infants is characterised by each of the following except: A cardiopulmonary deterioration in one-third of patients B increased cardiac size on chest X-ray C pharmacological responsiveness to indomethacin D an absence of clinical findings on cardiovascular examination E non-invasive evidence of shunting before physical exam findings are apparent.

Answer 29

D In premature infants, the ductus arteriosus is patent at birth. In some, it closes spontaneously, but in the majority the PDA persists for a prolonged period of time. Approximately one-third of patients will develop heart failure symptoms and require increased ventilator support. Pharmacological treatment with nonsteroidal anti-inflammatory drugs, such as indomethacin, results in closure of the PDA in most premature infants. In approximately 10%, surgical ligation is needed for ductal closure. The left-to-right shunt across the PDA results in increased left-heart return, correlating with cardiomegaly and increased pulmonary interstitial vascular markings on chest radiography. The premature lungs exacerbate this. The physical examination is notable for a machinery-type murmur, heard throughout systole and in early-to-mid diastole, also known as Gibson’s murmur. other findings include bounding peripheral pulses from run-off of blood into the pulmonary arteries during diastole, resulting in a widened pulse pressure. A hyperactive precordium and hepatomegaly may be present. Echocardiography is diagnostic and reveals left-to-right shunting across the PDA, as well as dilatation of the left atrium and the left ventricle at end diastole. Echocardiography may reveal a PDA before the development of symptoms, especially in the first few days after birth, or if the PDA is small. SPSE 1

Question 30

Concerning aortic coarctation, which of the following statements is correct? A The most common location of an aortic coarctation is preductal. B Aortic coarctation is associated with Turner’s syndrome. C The aortic valve is bicuspid in 10% of patients. D Inferior rib notching affects the first to eighth ribs. E Repair is typically via median sternotomy.

Answer 30

B Aortic coarctation is a narrowing of the aorta at the insertion of the ductus arteriosus into the proximal descending thoracic aorta. The most common location of coarctation is juxtaductal, and not proximal to the ductus arteriosus. A bicuspid aortic valve is present in approximately 50% of patients. Collateral arteries develop primarily from intercostal vessels, and provide blood flow to areas distal to the coarctation. over time, the enlarged intercostal vessels result in notching of the inferior aspect of the ribs, where the neurovascular bundle runs. These intercostal vessels arise from the subclavian arteries and their branches, including the internal mammary arteries. Notching is not seen in the first or second ribs, since the upper intercostal arteries in those ribs are not supplied by the subclavian artery. Aortic coarctation is present in approximately 20% of patients with Turner’s syndrome, and is the major congenital cardiac anomaly in Turner’s syndrome. In patients with a left aortic arch, which represents the majority of patients, repair is through a left thoracotomy, and not a median sternotomy. If there is associated proximal aortic arch hypoplasia, then repair is via median sternotomy on cardiopulmonary bypass with enlargement of the aortic arch with a patch. SPSE 1

Question 31

Which one of the following is the most reliable indicator of right atrial morphology? A Drainage of the superior vena cava into the atrium. B Drainage of the inferior vena cava into the atrium. C Presence of an atrial appendage that is triangular with a broad base. D Outflow into the tricuspid valve. E Presence on the right side of the heart.

Answer 31

B In normal hearts, all of the choices listed are correct. However, in complex congenital heart disease, only choice B definitively identifies the right atrium. Patients may have bilateral superior vena cavae, with the right superior vena cava draining into the right atrium and the left superior vena cava draining into the left atrium. In some patients, there is only one left-sided superior vena cava draining into the left atrium, which could be a morphological right atrium. The inferior vena cava, when present, will always drain into the right atrium. In patients with heterotaxy syndrome, the inferior vena cava may be interrupted below the liver, with continuation into the azygos vein that drains into the superior vena cava. The hepatic veins in those cases would drain directly into the atrium. In those cases, it may be difficult to determine which atrium is the morphological right atrium, a condition known as situs ambiguus. The right atrial appendage is triangular with a broad base, in contradistinction to the left atrial appendage, which is finger-like and long with a narrow base. In patients with heterotaxy of the asplenia variety (also known as right atrial isomerism), both atrial appendages are triangular with broad bases, requiring the presence of other anatomical landmarks to determine which atrium is the morphological right atrium. While the coronary sinus usually drains into the right atrium, it may be absent, or may be unroofed and drain into the left atrium. The atrium that is located on the right side of the heart may often be the morphological right atrium, although that is not a uniform finding. In patients with situs inversus totalis, the morphological right atrium is left-sided and the morphological left atrium is right-sided. In corrected transposition of the great arteries, the morphological right atrial outflow is through the mitral valve into the left ventricle then through the pulmonary valve into the pulmonary arteries. The morphological left atrial outflow is through the tricuspid valve into the right ventricle then through the aortic valve and aorta. SPSE 1

Question 32

A secundum ASD is a hole in which of the following structures? A atrioventricular septum B superior vena cava junction with the right atrium C septum secundum D septum primum E endocardial cushions

Answer 32

D ASDs are defects in the interatrial septum that result in left-to-right shunting of blood. This results in dilatation of the right atrium and right ventricle, with cardiomegaly on chest X-ray and right ventricular volume overload on echocardiography. Secundum ASDs are the most common type of ASDs, and represent defects in septum primum. In the embryonic heart, septum secundum forms to the right of septum primum; after birth it fuses with septum primum to close the foramen ovale and form the interatrial septum. Defects in the interatrial septum at the junction of the superior vena cava with the right atrium represent sinus venosus defects. ostium primum ASDs, also known as primum ASDs, represent defects within the endocardial cushions at the posterior and inferior aspects of the interatrial septum, at the junction of the tricuspid valve with the interatrial septum. The atrioventricular septum is the small part of the membranous septum of the heart just above the septal cusp of the tricuspid valve, separating the right atrium from the left ventricle. SPSE 1

Question 33

Partial anomalous pulmonary venous drainage is most commonly associated with which congenital cardiac abnormality? A atrioventricular canal defect B sinus venosus ASD C ventricular septal defect D secundum ASD E tetralogy of Fallot

Answer 33

B Anomalous pulmonary venous return represents abnormal drainage of the pulmonary veins into the heart. Patients with total anomalous pulmonary venous return (TAPVR) have all four pulmonary veins draining abnormally. Those are divided into supracardiac types (the most common subtype), intracardiac types and infracardiac types; the latter are invariably obstructed. Patients with partial anomalous pulmonary venous return have some pulmonary veins draining normally into the left atrium (often the left-sided veins), while one or more pulmonary veins drain abnormally, usually ending in the right atrium or inferior vena cava (the latter are associated with scimitar syndrome). While all of the choices listed may have anomalous pulmonary venous return, the most common congenital cardiac anomaly with partial anomalous pulmonary venous return is sinus venosus ASD. In that lesion, there is a defect in the interatrial septum at the junction of the superior vena cava with the right atrium. The right upper pulmonary vein is located in the normal anatomical position, but, because of the absence of the interatrial septum at the site where this vein normally drains into the atrium, the resultant drainage of blood is into the right atrium. Secundum ASDs are located in the central portion of the interatrial septum and are not typically associated with partial anomalous pulmonary venous return. Patients with endocardial cushion defects, also known as atrioventricular canal defects or atrioventricular septal defects, often, but not always, have normal pulmonary venous drainage. Tetralogy of Fallot is an anomaly of the right ventricular outflow tract with pulmonary stenosis and a ventricular septal defect; it is not usually associated with partial anomalous pulmonary venous return. SPSE 1

Question 34

Which of the following ventricular septal defects is least likely to close spontaneously? A perimembranous ventricular septal defect B muscular ventricular septal defect C inlet ventricular septal defect D apical ventricular septal defect E restrictive ventricular septal defect

Answer 34

C Ventricular septal defects are holes in the interventricular septum, which separates the right ventricle from the left ventricle. There are four types of ventricular septal defects: perimembranous defects (located in the membranous interventricular septum at the junction of the septal and anterior leaflets of the tricuspid valves), muscular defects (located anywhere in the muscular interventricular septum), inlet defects (located below the septal leaflet of the tricuspid valve), and conal septal defects (located in the conal septum that separates the aortic valve from the pulmonary valve). Perimembranous defects are the most common defects that are closed surgically. The bundle of His penetrates at the posterior inferior aspect of the ventricular septal defect and care should be taken at the time of surgical closure not to damage the conduction tissue, which may result in complete heart block. muscular ventricular septal defects are further subdivided into anterior muscular (located inferior to the pulmonary valve), midmuscular (located close to the moderator band), posterior muscular (located at the posterior septal tricuspid valve leaflet) and apical muscular (located in the apex of the ventricular septum). Restrictive defects are those that have a pressure gradient across the defect, which would be consistent with partial spontaneous closure of the defect. Spontaneous closure may be a result of hypertrophy of muscle bundles within the right ventricle, aortic valve prolapse, presence of tricuspid valve chordae and accessory tricuspid valve tissue, or the presence of a subaortic membrane on the left ventricular aspect of the ventricular septal defect. All of the defects listed may close spontaneously except for inlet ventricular septal defects, which never close. Conal septal defects, also known as outlet defects or supracristal defects, also do not close spontaneously, and require surgical closure. SPSE 1

Question 35

Which of the following ventricular septal defects is least likely to close spontaneously? A perimembranous ventricular septal defect B muscular ventricular septal defect C inlet ventricular septal defect D apical ventricular septal defect E restrictive ventricular septal defect

Answer 35

C Ventricular septal defects are holes in the interventricular septum, which separates the right ventricle from the left ventricle. There are four types of ventricular septal defects: perimembranous defects (located in the membranous interventricular septum at the junction of the septal and anterior leaflets of the tricuspid valves), muscular defects (located anywhere in the muscular interventricular septum), inlet defects (located below the septal leaflet of the tricuspid valve), and conal septal defects (located in the conal septum that separates the aortic valve from the pulmonary valve). Perimembranous defects are the most common defects that are closed surgically. The bundle of His penetrates at the posterior inferior aspect of the ventricular septal defect and care should be taken at the time of surgical closure not to damage the conduction tissue, which may result in complete heart block. muscular ventricular septal defects are further subdivided into anterior muscular (located inferior to the pulmonary valve), midmuscular (located close to the moderator band), posterior muscular (located at the posterior septal tricuspid valve leaflet) and apical muscular (located in the apex of the ventricular septum). Restrictive defects are those that have a pressure gradient across the defect, which would be consistent with partial spontaneous closure of the defect. Spontaneous closure may be a result of hypertrophy of muscle bundles within the right ventricle, aortic valve prolapse, presence of tricuspid valve chordae and accessory tricuspid valve tissue, or the presence of a subaortic membrane on the left ventricular aspect of the ventricular septal defect. All of the defects listed may close spontaneously except for inlet ventricular septal defects, which never close. Conal septal defects, also known as outlet defects or supracristal defects, also do not close spontaneously, and require surgical closure. SPSE 1

Question 36

A patient has a chest X-ray that shows increased pulmonary arterial markings, mild to moderate cardiomegaly, prominent pulmonary arteries, and lack of left atrial dilatation. Of the following congenital cardiac lesions, which is the most likely? A ventricular septal defect B tetralogy of Fallot C aortic coarctation D PDA E ASD

Answer 36

E The chest radiograph may be used to discriminate between various aetiologies of congenital heart disease. The presence of increased pulmonary arterial markings is consistent with increased pulmonary blood flow, as is seen with ventricular septal defects and PDA. These result in cardiomegaly, although cardiomegaly may also result from systemic hypertension, cardiomyopathy and obstruction to systemic blood flow. Prominent pulmonary arteries, and prominent pulmonary artery convexity, are often due to a left-to-right shunt, resulting in increased pulmonary blood flow and dilatation of the pulmonary arteries. Dilated and aneurysmal pulmonary arteries are also seen in tetralogy of Fallot with absent pulmonary valve syndrome. The left atrium is dilated in patients with ventricular septal defects and PDA due to increased left atrial return from pulmonary overcirculation. The left atrium is not dilated in ASDs due to the presence of the ASD and the decreased relative compliance of the left atrium compared with the right atrium. As a result, the blood shunts from the left atrium to the right atrium, resulting in right atrial dilatation and right ventricular volume overload. Patients with tetralogy of Fallot have a characteristic boot-shaped heart (‘coeur en sabot’) where the cardiac apex is displaced upwards. Tetralogy patients also have decreased pulmonary vascular markings due to decreased pulmonary blood flow from right ventricular outflow tract obstruction. The pulmonary arteries are not prominent and the left atrium is not dilated. SPSE 1

Question 37

Which of the following is not a true statement regarding tetralogy of Fallot? A A right aortic arch is present in 25% of patients with tetralogy of Fallot. B Tetralogy of Fallot is the most common cause of cyanosis in infants and children. C The ventricular septal defect is usually non-restrictive, large and anteriorly malaligned. D The degree of right-to-left shunting depends on the severity of obstruction to pulmonary blood flow. E The ventricular septal defect is located in the anterior muscular septum below the pulmonary valve.

Answer 37

E Tetralogy of Fallot is characterised by the presence of four features: (1) obstruction to pulmonary blood flow that may be valvar (at the level of the pulmonary valve), subvalvar (below the pulmonary valve, within the right ventricular infundibulum or outflow tract) and supravalvar (above the pulmonary valve, in the main pulmonary artery or its branches) – often, all three sites of obstruction to pulmonary blood flow are present concomitantly; (2) presence of an anteriorly malaligned ventricular septal defect that shunts blood from the right ventricle into the left ventricle due to the presence of right ventricular outflow tract obstruction, resulting in cyanosis – occasionally the obstruction to pulmonary blood flow is minimal, and the shunting will be left-to-right across the ventricular septal defect; (3) override of the aortic valve so that part of the aortic valve will lie over the right ventricle, while most (>50%) of the aortic valve will lie over the left ventricle; (4) development of right ventricular hypertrophy due to obstruction to pulmonary blood flow. Tetralogy of Fallot is further subdivided into three types, depending on the aetiology of obstruction to pulmonary blood flow: (1) tetralogy of Fallot with pulmonary stenosis, the most common type; (2) tetralogy of Fallot with pulmonary atresia, also known as pulmonary atresia with ventricular septal defect, where the main pulmonary artery and branch pulmonary arteries may be very small; and (3) tetralogy of Fallot with absent pulmonary valve, associated with congenital absence of the ductus arteriosus and to-and-fro passage of blood in utero across the absent pulmonary valve, resulting in aneurysmal dilatation of the pulmonary arteries and air trapping from bronchial obstruction due to the dilated pulmonary arteries. A right aortic arch is present in one-quarter of all patients, especially those with tetralogy of Fallot with pulmonary atresia, where collateral arteries develop from the aorta and provide additional sources of pulmonary blood flow. Tetralogy of Fallot is the most common cause of cyanosis beyond the neonatal period, and is present in approximately 10% of congenital heart disease patients. The ventricular septal defect is large and non-restrictive. There is anterior deviation (i.e. malalignment) of the distal conal septum compared with the proximal interventricular septum, such that the two ends of the interventricular septum (where the ventricular septal defect is located) are not in the same anatomical two-dimensional plane. The degree of right-to-left shunting across the ventricular septal defect depends on the severity of obstruction to pulmonary blood flow. The ventricular septal defect is located in the subaortic region, and is described as a perimembranous defect with anterior malalignment, also known as a conoventricular defect. It is not an anterior muscular ventricular septal defect (which would be located in the muscular interventricular septum below the pulmonary valve). SPSE 1

Question 38

Concerning the Blalock–Taussig shunt, which one of the following statements is correct? A It connects the subclavian artery to the pulmonary artery. B It is a conduit between the right atrium and the pulmonary artery. C It is an intra-atrial tunnel that connects the inferior vena cava to the pulmonary artery. D It connects the superior vena cava to the pulmonary artery. E It is a connection between the systemic right ventricle and the pulmonary artery.

Answer 38

A The Blalock–Taussig shunt was originally described by Drs Blalock and Taussig to provide increased pulmonary blood flow in patients with tetralogy of Fallot. The classic Blalock–Taussig shunt involved division of the subclavian artery with anastomosis end to side to the ipsilateral pulmonary artery. This allowed blood to bypass the obstruction in the right ventricular outflow tract, so that it may be oxygenated and subsequently pumped into the systemic circulation. The original Blalock–Taussig shunt continued to grow with the child, resulting in torrential pulmonary blood flow with time. This is now modified by placement of a polytetrafluoroethylene (PTFE) tube between the subclavian artery and the pulmonary artery, obviating the need for division of the subclavian artery. It is used for palliation of cyanotic congenital heart disease, including patients with tetralogy of Fallot and those with single ventricle physiology with decreased pulmonary blood flow. It is not a conduit between the right atrium and the pulmonary artery, as was done in earlier versions of the Fontan procedure. A lateral tunnel Fontan would consist of the placement of an intra-atrial tunnel that connects the inferior vena cava to the undersurface of the right pulmonary artery. This serves as the third and final palliation of single ventricle patients. The second-stage palliation of single ventricle patients is the Glenn shunt, which is an anastomosis between the superior vena cava and the right pulmonary artery. The Sano shunt is a conduit between the systemic right ventricle and the pulmonary artery bifurcation in patients with hypoplastic left heart syndrome. SPSE 1

Question 39

All of the following statements are true regarding long-term complications following the Fontan procedure except: A atrial arrhythmias are common B progressive clinical deterioration is uncommon C protein-losing enteropathy may occur and carries a high mortality D plastic bronchitis is a recognised complication E heart failure is a common cause of death.

Answer 39

B Single ventricle patients have either a dominant systemic right ventricle or left ventricle. Surgical palliation consists of a series of operations that eventually result in passive flow of blood into the pulmonary circulation, with active pulsatile flow from the ventricular mass into the systemic circulation. Typical palliation consists of three stages: the first stage involves augmenting or limiting pulmonary blood flow, depending on whether there is a decrease or increase in pulmonary blood flow, respectively. operations performed during this stage consist of the Norwood procedure for hypoplastic left heart syndrome, pulmonary artery banding for patients with increased pulmonary blood flow, or placement of a modified Blalock–Taussig shunt for patients with decreased pulmonary blood flow who are dependent on the PDA for pulmonary blood flow. Second-stage palliation consists of the Glenn shunt, also known as a superior cavopulmonary anastomosis, whereby the right superior vena cava is transected at the atrium and sutured directly to the right pulmonary artery. A bilateral Glenn procedure is indicated if there are bilateral superior vena cavae. A hemi-Fontan procedure is an alternative to the Glenn procedure and consists of a side-by-side anastomosis of the superior vena cava to the right pulmonary artery, with patch closure of the orifice of the superior vena cava within the atrium. Third-stage palliation consists of the Fontan procedure, which baffles blood from the inferior vena cava to the pulmonary arteries. Two types of Fontan operations are done: the lateral tunnel Fontan procedure, which involves placement of a piece of PTFE within the right atrium to baffle the inferior vena cava to the cardiac end of the superior vena cava, along with re-establishment of a connection between the right atrium and the undersurface of the right pulmonary artery. An alternative is the extracardiac Fontan procedure which consists of a tube of PTFE that is anastomosed end to end to the transected inferior vena cava, then anastomosed end to side to the right pulmonary artery. Complications following the Fontan procedure are common, and often result in progressive clinical deterioration, influenced by the systolic and diastolic function of the single ventricle, the degree of pulmonary vascular resistance, and the anatomical type of systemic ventricle. Atrial arrhythmias are common, and a number of patients will develop a slow junctional rhythm, requiring the implantation of an epicardial pacemaker. one dreaded long-term complication is protein-losing enteropathy, where protein is lost in the stool, as documented by a stool trypsin test. Treatment options are limited and may involve construction of a fenestration between the pulmonary and systemic venous chambers to result in a decrease in the elevated pressures in the systemic venous chamber. Cardiac transplantation is usually curative. Plastic bronchitis is another dreaded complication where bronchial casts develop that may be removed during bronchoscopy. Recurrence is the rule and survival is poor without cardiac transplantation. Heart failure is a common cause of death, due to dysfunction of the single systemic ventricle. SPSE 1

Question 40

Polysplenia is characterised by which one of the following features? A Bilateral atrial appendages with triangular morphology and wide ostia. B More severe and complex cardiac anomalies than asplenia. C An association with azygos continuation of the inferior vena cava. D Bilateral eparterial bronchi. E Three lobes in each of the right and left lungs.

Answer 40

C Polysplenia and asplenia represent the two forms of heterotaxy syndrome, which involves abnormalities of sidedness. Normally, the liver is on the right and the spleen is on the left, with the right atrium receiving inferior vena caval blood. The right lung has three lobes while the left lung has two lobes. Polysplenia is also known as bilateral left-sidedness, or left atrial isomerism. There are multiple spleens present on the left side of the abdomen. The right lung has two lobes, and so does the left lung. The atrial appendages are both left atrial appendages, with long finger-like morphology and narrow ostia. The inferior vena cava may be normal or may be interrupted with azygos vein continuation into the superior vena cava. Associated cardiac malformations are usually less severe than in asplenia, which is characterised by the absence of a spleen. In both asplenia and polysplenia, splenic function is depressed; as a result, patients are susceptible to infections with encapsulated organisms, and lifelong amoxicillin prophylaxis has been advocated. In asplenia, also known as bilateral right-sidedness or right atrial isomerism, the atrial appendages are both right atrial appendages, characterised by triangular morphology with a broad base and wide ostia. There are three lobes in each of the right and left lungs. The right superior lobar bronchus is the only bronchus that is superior to the right pulmonary artery, and is termed an eparterial bronchus. In asplenia, there are bilateral eparterial bronchi because of the presence of bilateral right-sided lungs. In polysplenia, the bronchi are hyparterial, i.e. below (inferior) to the ipsilateral pulmonary arteries. SPSE 1

Question 41

The most common type of obstructed TAPVR is: A infracardiac type B supracardiac type C intracardiac type D mesocardiac type E mixed type.

Answer 41

A TAPVR is characterised by drainage of all four pulmonary veins into a pulmonary venous confluence, which subsequently drains into the right atrium via a supracardiac connection, an intracardiac connection or an infracardiac connection. Supracardiac TAPVR is the most common type, representing approximately 45% of patients. There is an ascending vertical vein that drains the pulmonary venous confluence into the left innominate vein, the azygos vein or the superior vena cava. When drainage is into the azygos vein, there is uniformly obstruction of pulmonary venous return. When drainage is into the superior vena cava, obstruction develops in approximately 65% of patients, while obstruction develops in 40% of patients when drainage is into the left innominate vein. only approximately 20% of TAPVR is of the intracardiac type, typically draining into the coronary sinus, or less often directly into the right atrium. obstruction develops in approximately 20% of those patients. Infracardiac TAPVR is characterised by a descending vertical vein that penetrates the diaphragm and connects with the portal vein or its branches. obstruction is invariably present, resulting in elevated pulmonary venous pressures, white-out on the chest radiograph, poor oxygenation and metabolic acidosis. Surgery is the only option as these patients do not respond to nitric oxide or to prostaglandins. mixed TAPVR is a combination of any of the three types of drainage; obstruction is present in approximately 40% of mixed TAPVR. There is no entity known as mesocardiac TAPVR. SPSE 1

Question 42

When present, a left superior vena cava most often drains directly into which of the following structures? A left atrium B coronary sinus C pulmonary vein D inferior vena cava E innominate vein

Answer 42

B There are two drainage patterns to a left superior vena cava. Typically, the left superior vena cava travels in the left atrioventricular groove posterior to the heart and joins the coronary sinus to drain into the right atrium. This normal variant has no physiologic consequence, although it does limit visibility within the heart when the right atrium is opened during open-heart surgery. There may be an innominate vein of normal size, although often the innominate vein is small or absent. The other drainage pattern of the left superior vena cava is directly into the roof (superior aspect) of the left atrium, close to the orifice of the left upper pulmonary vein and the base of the left atrial appendage. In those cases, known as the Raghib association, the left superior vena cava needs to be baffled to the right atrium, usually by construction of a pathway on the superior aspect of the left atrium to drain it into the right atrium at the interatrial septum. The other sites mentioned are not drainage sites of the left superior vena cava. SPSE 1

Question 43

The most common type of obstructed TAPVR is: A infracardiac type B supracardiac type C intracardiac type D mesocardiac type E mixed type.

Answer 43

A TAPVR is characterised by drainage of all four pulmonary veins into a pulmonary venous confluence, which subsequently drains into the right atrium via a supracardiac connection, an intracardiac connection or an infracardiac connection. Supracardiac TAPVR is the most common type, representing approximately 45% of patients. There is an ascending vertical vein that drains the pulmonary venous confluence into the left innominate vein, the azygos vein or the superior vena cava. When drainage is into the azygos vein, there is uniformly obstruction of pulmonary venous return. When drainage is into the superior vena cava, obstruction develops in approximately 65% of patients, while obstruction develops in 40% of patients when drainage is into the left innominate vein. only approximately 20% of TAPVR is of the intracardiac type, typically draining into the coronary sinus, or less often directly into the right atrium. obstruction develops in approximately 20% of those patients. Infracardiac TAPVR is characterised by a descending vertical vein that penetrates the diaphragm and connects with the portal vein or its branches. obstruction is invariably present, resulting in elevated pulmonary venous pressures, white-out on the chest radiograph, poor oxygenation and metabolic acidosis. Surgery is the only option as these patients do not respond to nitric oxide or to prostaglandins. mixed TAPVR is a combination of any of the three types of drainage; obstruction is present in approximately 40% of mixed TAPVR. There is no entity known as mesocardiac TAPVR. SPSE 1

Question 44

All of the following are complications of closure of PDA except: A pulmonary artery injury B chylothorax C diaphragmatic paralysis D hoarseness E Horner’s syndrome.

Answer 44

E Surgical closure of a PDA, typically performed via a left thoracotomy, may result in a number of surgical complications. If the PDA is not identified accurately, the wrong vessel may be ligated. Accidental closure of the aortic isthmus, transverse aortic arch and left pulmonary artery have been described, and usually involves misidentification of the anatomical landmarks. The left subclavian artery invariably enters the distal aortic arch; this should identify the aortic arch, and distinguish it from the ductus arteriosus, which should be inferior (caudad) to the arch. When the PDA is large, the ductal arch may be confused with the aortic arch, resulting in ligation of the aortic arch. The left recurrent laryngeal nerve, a branch of the left vagus nerve, lies in close proximity to the undersurface of the PDA. It encircles the PDA before ascending into the neck to innervate the left vocal cord. If the left recurrent laryngeal nerve, or the vagus nerve superior to the takeoff of the left recurrent laryngeal nerve, is injured (by electrocautery, traction, ligation or division), hoarseness will result, as well as feeding intolerance, as manifested by aspiration in the neonate. The left phrenic nerve may be injured by overzealous retraction of the lung and pleura for surgical exposure. There are a number of small lymphatic vessels that may be injured during surgery, resulting in chylothorax. Invariably, this is a self-limited condition that resolves with time. Injury to the stellate ganglion of the sympathetic nervous system results in Horner’s syndrome, manifested by ptosis (drooping of the upper eyelid from loss of sympathetic innervation to the superior tarsal muscle), miosis (pupillary constriction) and anhidrosis (decreased sweating on the affected side of the face). This typically arises following extensive dissection of the left subclavian artery, which is not done during surgical PDA ligation. SPSE 1