Congenital Heart Disease

Question 1

congenital left to right shunts

Answer 1

•atrial septal defect (ASD) •ventricular septal defect (VSD) •atrioventricular septal defect (AVSD) •patent (persistent) ductus arteriosus (PSD) •aycanotic

Question 2

congenital right to left shunts

Answer 2

•tetralogy of Fallot •transposition of the great arteries (TGA) •truncus arteriosus -above are conotruncal defects •tricuspid atresia •total anomalous pulmonary venous connection (TAPVC) •cyanotic

Question 3

congenital obstructions

Answer 3

•pulmonary stenosis •aortic stenosis •coarctation of aorta •acyanotic

Question 4

congenital regurgitation

Answer 4

•Ebstein’s Anomaly •cyanotic

Question 5

Eisenmenger Syndrome

Answer 5

•reversal of left to right shunt to a right to left shunt, occurring as a result of the interval development of significant pulmonary hypertension and increased vascular resistance •acyantotic to cyanotic

Question 6

most common cardiovascular anomaly

Answer 6

•bicuspid aortic valve

Question 7

most common cardiac anomaly

Answer 7

•ventricular septal defect

Question 8

pulmonary hypertension

Answer 8

•increased blood pressure in the lungs •congenital heart disease can cause pulmonary hypertension over time if shunts are present •results in hypertrophy of pulmonary arteries and formation of “plexiform lesions (twisted balls of proliferating capillary channels), a severe form of pulmonary hypertension called “plexiform pulmonary hypertension” -irreversible once they form -most common with VSD, less common with PDA, much less common with ASD •when severe, causes Eisenmenger syndrome

Question 9

atrial septal defect (ASD)

Answer 9

1) Abnormal opening between the two atria (other than a patent foramen ovale [PFO]). 2) Three types of ASDs: a. Secundum-type: At fossa ovalis - most common type of ASD (90% of cases) b. Primum-type: Low on septum, adjacent to AV valves (uncommon). c) Sinus venosus-type: High on septum, near superior vena cava (rare). 3) May be asymptomatic until adulthood. 4) Secondary cardiac effects: RV hypertrophy and dilatation, RA and LA dilatation 5) Pulmonary hypertension is infrequent (<10% of cases) and, if it does occur, it’s a late complication.

Question 10

ventricular septal defect (VSD)

Answer 10

1) Abnormal opening between right and left ventricles. 2) Two types: a. Membranous VSD: Involves membranous septum – most common type of VSD (90% of cases), and often large. b. Muscular VSD: Involves muscular septum; may be multiple; usually small. 3) If large (and unoperated), VSD will eventually cause pulmonary hypertension in 100% of cases, with reversal of the shunt (conversion to a right-to-left shunt) and conversion to cyanotic heart disease (Eisenmenger syndrome). 4) If small, VSD usually spontaneously closes, no surgery is needed, and no pulmonary hypertension ever develops; spontaneous closure occurs in the 1st year of life in >60% of cases

Question 11

pathophysiology of ASD

Answer 11

•VOLUME LOAD •An ASD allows left to right shunting at the atrial level (LA pressure is higher than RA pressure after birth). Given the low pressure in the atria, there is insufficient velocity of blood flow across the atrial septum to cause a murmur. However, over time (years), the excessive flow will lead to volume overload in the RA and RV. As the heart tries to cram extra blood across tricuspid and pulmonary valves that are only designed to take one ‘unit’ of blood per cardiac cycle, the blood will speed up to accommodate this. This mild increased flow velocity can cause soft diastolic (tricuspid valve) and/or systolic ejection (pulmonary valve) murmurs. Over years, the excess flow leads to right heart enlargement. This can lead to: 1) Atrial dysrhythmias 2) Pulmonary vascular occlusive disease 3) RV dysfunction These do not typically occur until the 3rd or 4th decade of life, and pediatric CHF almost never occurs. It is extremely uncommon for a child to have symptoms from an ASD before the age of 10 years. ASD are volume lesions, not pressure, so it takes much longer for symptoms and irreversible changes to occur.

Question 12

interventions for ASD

Answer 12

•Given the long time course until irreversible damage, ASDs are typically repaired electively, usually before kindergarten, if diagnosed early enough. If the child, or young adult, is older at diagnosis, they can be closed at that time. However, it will be important to confirm that the pulmonary arterial resistance is normal before closing a defect, and this can only be done by cardiac catheterization. The first line treatment of secundum ASDs is now catheter-based, device closure. However, larger or more complex defects still require surgical closure with a median sternotomy and cardiopulmonary bypass.

Question 13

pathophysiology of VSD

Answer 13

•PRESSURE LOAD •A VSD causes left to right shunting at the ventricular level. However, the blood spends almost no time within the right heart, and is almost immediately ejected to the pulmonary artery. Blood through the VSD joins systemic venous blood, leading to excessive flow to the pulmonary arteries and increased blood return to the left heart. The pathophysiology is very similar to that of a PDA (CHF, PVOD/Eisenmenger, left heart dilation). The LV pressure is higher than the RV pressure for the entirety of systole, so VSDs cause holosystolic murmurs.

Question 14

intervention for VSD

Answer 14

•Symptomatic infants with VSDs can be trialed on medication (diuretics, ACE-inhibitors) to help reduce pulmonary overcirculation and encourage growth, but typically if a baby needs medication, they really need a ‘cold steel cure’ (surgery). VSDs are typically closed between 4 and 6 months of age via a median sternotomy and cardiopulmonary bypass. There are occasions when a VSD may be appropriate for catheter-based device closure, but this is the exception not the rule with current technology.

Question 15

atrioventricular septal defect (AVSD)

Answer 15

•1) Deficient AV septum, associated with mitral and tricuspid valve anomalies; also called an “endocardial cushion defect”, due to failure for the embryologic endocardial cushions to fuse in the center of the heart; also called “atrioventricular canal defect”, because a canal-like hole is present in the center of the heart. 2) Two types: a. Partial AVSD: Primum ASD with cleft mitral anterior leaflet (and mitral regurgitation). b. Complete AVSD: Primum ASD and membranous VSD, producing a single large hole in the center of the heart and a common AV valve (instead of separate mitral and tricuspid valves). 3) Strongly associated with Down syndrome (20% of Down syndrome patients have an AVSD, especially a complete AVSD). •The VSD component is often quite large and the two ventricles act as a single chamber, so there is not typically a VSD murmur. The most common murmur is a systolic ejection murmur at the pulmonary valve due to the excessive flow across it.

Question 16

pathophysiology of AVSD

Answer 16

•PRESSURE and VOLUME LOAD •An AVSD causes left to right shunting at both the atrial and ventricular level. This leads to excessive flow to the pulmonary arteries and increased blood return to the left heart. The pathophysiology is very similar to that of a VSD (CHF, PVOD/Eisenmenger, left heart dilation), however given the large shunt volume, symptoms of CHF are more likely and at a younger age.

Question 17

intervention for AVSD

Answer 17

•Symptomatic infants with AVSDs can be trialed on medication (diuretics, ACE-inhibitors) to help reduce pulmonary overcirculation and encourage growth, but typically if a baby needs medication, they really need a ‘cold steel cure’ (surgery). AVSDs are typically closed between 4 and 6 months of age via a median sternotomy and cardiopulmonary bypass. These defects are never appropriate for catheter-based device closure.

Question 18

patent ductus arteriosus

Answer 18

1) Persistence of normal fetal structure (ductus normally undergoes functional closure within 12 hrs of birth, and structural [permanent] closure by 3 months of age). 2) Isolated defect in most cases. 3) Approximately 80% of patients will develop pulmonary hypertension (if unoperated), usually after age 5 yrs. 4) May be required for survival in some complex cyanotic (“ductus-dependent”) congenital heart diseases, such as aortic valve atresia or pulmonary valve atresia (if the ductus is allowed to undergo normal physiologic closure after birth in these conditions, the baby will die) •Since the aortic pressure is always significantly higher than the pulmonary artery pressure in systole and diastole, PDAs cause continuous, machine-like murmurs.

Question 19

pathophysiology of PDA

Answer 19

•PRESSURE LOAD •If a PDA is large, it is basically an open communication between the systemic and pulmonary vasculature and can lead to increased flow and pressure in the pulmonary arteries (normally should be 25 – 30% of systemic pressure). Excessive flow to the pulmonary arteries can lead to several problems: 1) Pediatric congestive heart failure (CHF), or pulmonary overcirculation. In this situation, the excess flow leads to pulmonary edema, which decreases the efficiency of gas exchange and causes tachypnea to compensate. In addition, the total cardiac output (volume ejected by both ventricles) increases, so the heart is working harder too. Now, there is increased oxygen demand and a decreased efficiency in getting oxygen into the body. Add to this that feeding is exercise for a baby (like running up a flight of stairs), and you have a tachypneic baby with a revved up metabolism and an inability to eat well – this leads to poor weight gain in infants. 2) Pulmonary vascular occlusive disease. The pulmonary arterioles respond to the increased pressure and flow by constricting. If the infant is able to survive their CHF and remain with high pressure and flow to the lungs for a prolonged period (years), the arterioles muscularize and lose the ability to relax, leading to fixed elevated pulmonary arterial resistance and eventually right to left shunting through the PDA (this is Eisenmenger syndrome and is bad!). 3) Excessive blood return to the left heart. This leads to LV dilation and increased end-diastolic pressure and wall stress. 4) Endarteritis risk. There is approximately 1%/year risk of infection of a PDA (endarteritis) likely from the turbulent flow in the area being a potential site of bacteria setting up infection.

Question 20

intervention for PDA

Answer 20

Symptomatic infants, typically very premature, may need their PDA closed early in life. This is first attempted with indomethacin or ibuprofen, prostaglandin inhibitors, which can stimulate ‘natural’ PDA closure. Those that fail medical therapy and are still symptomatic may require surgical ligation via a lateral thoracotomy and without cardiopulmonary bypass. Those who do not have significant neonatal symptoms, and if the PDA is still present after a year of life, can undergo elective catheter-based closure of the PDA.

Question 21

pulmonary valve stenosis

Answer 21

1) Pulmonary valve obstruction, due to hypoplasia, dysplasia, atresia, or abnormal number of cusps. 2) Two types, based on severity of obstruction: a) Isolated PV Stenosis: Causes RV hypertrophy, tricuspid regurgitation, dilatation of RA, and dilatation of pulmonary artery; may be asymptomatic until adulthood. b) PV Atresia with Intact Ventricular Septum: PDA required for survival; RV and tricuspid valve are hypoplastic. •When the pulmonary valve is being formed, sometimes the leaflet separation is halted, leading to a valve that does not open completely. Some patients also have thickening (dysplasia) of the leaflets which can lead to additional obstruction to flow out of the RV. Pulmonary stenosis is associated with a harsh systolic ejection murmur, typically at the left upper sternal border with radiation to the periphery and back.

Question 22

pathophysiology for PS

Answer 22

•PRESSURE LOAD •Chronic obstruction of flow out of the RV produces a pressure load on the ventricle. The heart responds to pressure loads in two ways: 1) Hyperplasia (neonates only) – the heart grows more myocytes to deal with the increased work 2) Hypertrophy (neonates and older children) – the existing myocytes enlarge to deal with the increased work Hyperplasia produces more efficient work, and therefore, neonates can handle the pressure load better than older children and adults. It is not uncommon for a neonate with pulmonary valve stenosis to have RV pressure that is double the LV pressure and be completely asymptomatic. Eventually, the RV may dilate as it loses the ability to generate forceful contractions. Through ventriculo-ventricular interactions (two pumps, limited pericardial space to work in), the dilated RV can limit LV filling and subsequently, limit cardiac output.

Question 23

intervention for PS

Answer 23

Intervention timing varies with age. Neonates with critical PS (require the PDA to have adequate pulmonary flow) need intervention regardless of the degree of obstruction as estimated by echo. For older infants and children, typically a peak echo gradient of at least 40 mmHg is the criteria for intervention. Historically, PS was treated with a surgical valvotomy. This has almost completely been replaced by catheter-based balloon valvuloplasty which works by completing the separation of the valve leaflets (like tearing the perforation on coupons). Thick, dysplastic valves do not always respond well to balloon valvuloplasty because there is still thick tissue obstructing flow. Balloon valvuloplasty can lead to new pulmonary regurgitation, but this is often tolerated well for many years before any (surgical) intervention is needed.

Question 24

aortic stenosis

Answer 24

1) Aortic valve obstruction, due to hypoplasia, dysplasia, atresia, or abnormal number of cusps. 2) Two types, based on severity of obstruction: a) Isolated AV Stenosis: Causes LV hypertrophy, mitral regurgitation, dilatation of LA. b) AV Atresia with Intact Ventricular Septum (“Hypoplastic Left Heart Syndrome” [HLHS]): PDA required for survival; LV is hypoplastic; mitral valve is hypoplastic; ascending aorta is hypoplastic. HLHS represents about 1% of cases of congenital heart disease. •When the aortic valve is being formed, sometimes the leaflet separation is halted, leading to a valve that does not open completely. Some patients also have thickening (dysplasia) of the leaflets which can lead to additional obstruction to flow out of the LV. Many patients with AS will have a bicuspid, or even unicuspid, valve that does not function properly. These valves may also have associated regurgitation if they cannot close completely. Aortic stenosis is associated with a harsh systolic ejection murmur, typically at the right upper sternal border with radiation to the neck and back.

Question 25

pathophysiology of AS - neonates

Answer 25

•PRESSURE LOAD •Chronic obstruction of flow out of the LV produces a pressure load on the ventricle. •Presentation and pathophysiology vary based on the age of presentation. Neonates (critical AS) In utero, the LV typically deals with a low afterload (placenta), as opposed to the RV which also pumps against the higher resistance pulmonary vasculature, so the LV does not have to work as hard. In addition, the RV can help support systemic flow via the ductus arteriosus in utero. However, once the baby is born and the umbilical cord is clamped, there is a sudden increase in systemic afterload on top of the aortic valve obstruction, and the LV may not be able to handle the increased work. In addition, if the LV has been working hard for a while in utero, there may already be diastolic dysfunction, particularly if the ventricle has not grown as well. This diastolic dysfunction can lead to increased LV end-diastolic pressure, increased LA pressure, increased pulmonary venous pressure and eventually increased PA and RV pressure. The RV can dilate in response to this and limit LV filling further, creating a vicious cycle and a very sick neonate.

Question 26

pathophysiology of AS - older children

Answer 26

•PRESSURE LOAD •Chronic obstruction of flow out of the LV produces a pressure load on the ventricle. Presentation and pathophysiology vary based on the age of presentation. •Older children are rarely symptomatic from their AS, and are often diagnosed after being evaluated for a murmur. Since the onset of worsening obstruction is slower, they are able to maintain LV systolic performance through hypertrophy. While there can eventually be diastolic dysfunction secondary to the hypertrophy, this is usually a late finding. It is possible for older children to present with a syncopal episode due to an inability to increase cardiac output during exercise because of fixed obstruction to LV outflow.

Question 27

intervention for AS

Answer 27

•Intervention timing varies with age. Neonates with critical AS (require the PDA to have adequate pulmonary flow) need intervention regardless of the degree of obstruction estimated by echo. They typically have poor ventricular function and cannot generate a significant gradient. For older infants and children, typically a peak cath gradient of at least 50 mmHg is the criteria for intervention (40 mmHg if symptomatic or want to be active or get pregnant). Historically, AS was treated with a surgical valvotomy. This has almost completely been replaced by catheter-based balloon valvuloplasty which works by completing the separation of the valve leaflets (like tearing the perforation on coupons). Thick, dysplastic valves do not always respond well to balloon valvuloplasty because there is still thick tissue obstructing flow. For critical AS, there is a 10% procedural mortality – these are sick neonates! A sometimes catastrophic results can be the development of acute aortic regurgitation after valvuloplasty, which is not often tolerated well and may require urgent surgical intervention.

Question 28

coarctation of aorta (CoA)

Answer 28

1) Ridge-like indentation or narrowing of distal aortic arch, across from ductus arteriosus. 2) Two types: a. With PDA (presents in infants). b. Without PDA (presents in adults). 3) 50% of patients also have a congenitally bicuspid aortic valve. 4) 3 - 4 times more common in males, but also associated with Turner Syndrome. 5) Hypertension in arms, hypotension in legs, and shunting around narrowing through enlarged collateral arteries.

Question 29

pathophysiology of CoA - neonates

Answer 29

•The pathophysiology and presentation of CoA can vary with age. •Neonates (critical CoA) Neonates with severe coarctation are usually completely asymptomatic. They often present around 1 week of life (80% within the first 2 weeks of life) with poor perfusion, CHF (pump failure), acidosis and shock. WHY? A better way to diagnose critical coarctation is with a thorough physical exam in the Newborn Nursery and noting that there are no palpable femoral pulses, indicating inadequate lower body perfusion distal to the coarctation. They may have a systolic ejection murmur if there are associated aortic valve abnormalities.

Question 30

pathpphysiology of CoA - older children

Answer 30

•The pathophysiology and presentation of CoA can vary with age. •Older children have a slower onset of obstruction. This allows the LV time to compensate with hypertrophy. They are also able to generate collateral arteries that bypass the coarctation to provide (abnormal) flow to the lower body. As the high velocity, turbulent flow continues in the region of the coarctation, the fibrosis can progress and in extreme cases patients can develop acquire aortic atresia. Chronic LV hypertrophy can lead to diastolic dysfunction. These patients may have systolic ejection murmurs if there are associated aortic valve abnormalities and bruits over the back from collateral arteries. Other associated findings include upper extremity hypertension, headaches, leg pain/claudication and decreased femoral pulses.

Question 31

interventions for CoA

Answer 31

Intervention varies with the age of presentation. Neonates and young children often have associated aortic arch hypoplasia and require surgical reconstruction of their arch. Young children can be treated with surgery or possibly catheter-based balloon angioplasty, although there is a risk for aneurysm development. Older children and adults can be treated with catheter-based stent placement, which is lower risk for aneurysm development. Surgery is still considered the standard of care, but this is evolving, particularly for older patients

Question 32

Tetralogy of Fallot

Answer 32

1) Presence of 4 simultaneous anomalies: VSD (large and subaortic), subpulmonary stenosis, overriding aorta, and right ventricular hypertrophy. 2) Most common form of cyanotic congenital heart disease. 3) Results from anterosuperior displacement of the infundibular septum during cardiac development. 4) Three types, based on severity of pulmonary stenosis: a) “Pink Tetralogy”: Mild pulmonary stenosis; NO cyanosis. b) “Classic Tetralogy”: Moderate to severe pulmonary stenosis, WITH cyanosis. c) “Pulmonary Atresia-Ventricular Septal Defect (PA-VSD)”: Variant of Tetralogy with complete absence of pulmonary valve and main pulmonary artery, WITH cyanosis. 5) Usually patients do NOT develop pulmonary hypertension, despite the presence of a VSD, because lung vessels are protected by subpulmonary stenosis. 5) Often good results with surgical repair. •In the developing fetal heart, there is initially a common arterial trunk that arises completely from the RV. Normally, this vessel will divide into two vessels which spiral around one another and shift leftward so that the aorta arises from the LV and the pulmonary artery arises from the RV. The common arterial trunk is divided by the conotruncal septum, which is one of the components that form the crux of the heart. If the conotruncal septum deviates anteriorly, then it will not connect with the muscular ventricular septum and a VSD will form. The anterior deviation of the septum drags the aorta anteriorly with it, so that it overrides the VSD. The deviated septum blocks the region under the pulmonary valve (sub-pulmonic stenosis), and the obstruction leads to RV hypertrophy.

Question 33

pathophysiology of Tetralogy of Fallot

Answer 33

•The large VSD of ToF allows blood to shunt between the two ventricles. Typically, blood should shunt from the left to right ventricle. However, blood ‘flows downhill’ from a higher pressure chamber (or vessel) to a lower pressure chamber (or vessel). The sub-pulmonic obstruction creates a situation where blood will more likely shunt right to left, causing systemic desaturation (cyanosis). In a tet (or hypercyanotic) spell, there is a transient increase in RV outflow obstruction which leads to increased right to left shunting. The resultant hypoxia further increases the vasoconstriction of the distal pulmonary arteries, forcing more right to left shunting. These episodes can result in extreme cyanosis and even death if not treated. Typically, maneuvers to increase systemic arterial and decrease pulmonary arterial resistance will lead to less right to left shunting and normalize the saturations. These maneuvers include: 1) Oxygen supplementation (lower pulmonary resistance) 2) Sedation (lower pulmonary resistance, decrease oxygen demand) 3) Squatting (increase systemic resistance) 4) Administer vasoconstrictors, phenylephrine is classic (increase systemic resistance) 5) Emergency surgical intervention (last resort) ToF is associated with a long systolic ejection murmur at the left upper sternal border with radiation to the periphery and back. You do NOT hear the VSD (why?)

Question 34

intervention for ToF

Answer 34

Classically, and in cases of extreme cyanosis in younger infants, a Blalock-ThomasTaussig (BTT) shunt is the first intervention for patients with ToF. This was the first surgery performed for cyanotic congenital heart disease. A BTT shunt is essentially a surgical PDA, where a tube attaches the right subclavian artery and right pulmonary artery to augment flow to the pulmonary arteries. The procedure is typically performed via a lateral thoracotomy without cardiopulmonary bypass. This is a temporizing measure, and not performed in every patient anymore. At 4 to 6 months of age, a complete repair is performed, whether or not the patient had a BTT shunt or not. This involves closing the VSD and enlarging the RV outflow tract, sometimes with a transannular patch (cut open the pulmonary artery, crossing the pulmonary valve annulus, and sew in a patch to make it larger). In some more complex forms of ToF, the native pulmonary artery is not salvageable, and a conduit must be implanted to connect the RV to the PAs. These surgeries are performed via median sternotomy on cardiopulmonary bypass.

Question 35

transposition of the great arteries (TGA)

Answer 35

1) Aorta arises from the right ventricle, and pulmonary artery from the left ventricle. 2) Incompatible with post-natal life unless a shunt is also present (VSD, PDA, ASD, PFO). 3) Two types, based on status of ventricular septum: a) TGA + intact ventricular septum: 65% of cases; pulmonary hypertension is rare. b) TGA + VSD: 35% of cases; severe pulmonary hypertension occurs in almost all cases (if unoperated). •This is another conotruncal defect. As the common arterial trunk forms, if it divides and shifts leftwards, but does not spiral, then you have a situation where the aorta arises from the RV and the pulmonary arteries from the LV. Looking at the fetal circulation in these babies, they maintain relatively normal saturations from the shunting through the foramen ovale and ductus arteriosus (normal fetal PaO2 is in the 40s), but the brain does receive the more deoxygenated blood.

Question 36

pathophysiology of TGA

Answer 36

The problem with TGA is that you have two parallel circuits pumping the blood, so the pulmonary venous blood is sent directly back to the lungs and the systemic venous blood is sent directly back to the body. This results is profound cyanosis very quickly – these are the most cyanotic patients you will see. However, the PDA allows increased flow to lungs and some oxygenated blood to flow to the body from bidirectional shunting. We can give babies prostaglandin E (PGE) to keep the PDA open and allow this mixing to continue. In addition, PGE decreases the pulmonary resistance. Lower pulmonary resistance increases flow from aorta to pulmonary arteries, which leads to increased pulmonary venous flow which increases the left atrial pressure. Increased left atrial pressure closes the PFO. Further increases in left atrial pressure increase pulmonary arterial resistance which can actually decrease flow through the PDA to the pulmonary arteries. While all of this is happening, the neonate is becoming more hypoxic, which leads to metabolic acidosis. Hypoxia and acidosis both increase pulmonary arterial resistance, further decreasing pulmonary flow (and the amount of oxygenated blood). This lesion is does not typically produce a murmur unless there are other associated defects (PS, VSD, etc). These patients will have a single S2 (why?)

Question 37

intervention for TGA

Answer 37

The PDA, and occasional VSD, are communications between the two vascular beds that can allow some degree of shunting, but these are communications between high pressure structures, which may not allow for good mixing of oxygenated and deoxygenated blood. The more oxygenated blood that you can get to the right ventricle to pump to the body, the better the baby will be. So, the ideal chambers for mixing are the atria which are low pressure. For infants who are critically ill and markedly cyanotic, you may need to perform an emergent balloon atrial septostomy to create a larger atrial communication and maximize mixing. A special balloon tipped catheter is advanced through the IVC, often via the umbilical vein, across the atrial septum into the LA. The balloon is inflated and quickly jerked back to tear a large hole in the septum. When successful (i.e., you don’t tear the heart off the pulmonary veins or the IVC off the heart), then the sats should rise quite quickly and acidosis will quickly improve. Infants with adequate ASDs at birth likely will not need a septostomy. In the first 1 to 2 weeks of life, once they have stabilized, they undergo a surgical arterial switch procedure via median sternotomy on cardiopulmonary bypass. The aorta and pulmonary artery are cut, the coronaries transferred and the arteries reattached so that they arise from the correct ventricles.

Question 38

truncus arteriosus

Answer 38

1) Aorta and pulmonary artery arise from a single truncal artery that receives blood from both ventricles. 2) Due to failure of separation of the embryonic truncus arteriosus into the aorta and pulmonary artery. 3) A large VSD is also present in most patients. 4) Severe pulmonary hypertension often occurs. 5) Strongly associated with DiGeorge syndrome (22q11.2 deletion). •This is another conotruncal defect. The common arterial trunk never fully separates into two vessels so you have one semilunar valve that overrides a large VSD and one great artery that provides branches to the body and branch PAs.

Question 39

pathophysiology of truncus arteriosus

Answer 39

Since there is only one outlet that both ventricles share, all of the oxygenated and deoxygenated blood mixes before leaving the heart, resulting in cyanosis. As pulmonary arterial resistance drops, more flow goes to the lungs leading to pediatric CHF (VSD physiology). This defect is typically associated with a systolic ejection murmur. You do NOT hear the VSD (why?)

Question 40

interventions for truncus arteriosus

Answer 40

The circulatory beds need to be separated, typically in the first weeks of life. Since the systemic blood supply is more important and more difficult to recreate surgically, the common arterial trunk and semilunar valve are committed to the systemic circulation. The VSD is closed and the pulmonary artery branches are removed from the common arterial trunk and connected to the RV with a conduit.

Question 41

tricuspid artresia

Answer 41

1) Absence of tricuspid valve with hypoplasia of right ventricle. 2) ASD is always present. •There are many variations of single ventricle anatomy and physiology, but essentially, there is one pump for two circulatory beds, sort of the opposite of Truncus. Unfortunately, we are not able to surgically recreate a ventricle like we can a pulmonary artery, so these are more challenging to treat.

Question 42

pathophysiology of tricuspid artresia

Answer 42

Regardless of the type, all of the oxygenated and deoxygenated blood mixes in the single ventricle and is pumped to at least one great artery. Often the artery that arises from the hypoplastic ventricle is also compromised and inadequate. PGE can be given to keep the PDA open to allow for blood to flow to the compromised circulatory bed. However, this is only a temporary measure as you cannot send a baby home on continuous PGE infusion.

Question 43

intervention for tricuspid artresia

Answer 43

The ultimate goal of single ventricle palliation (we cannot repair this) is to separate the systemic and pulmonary circulations. This is achieved through a series of 3 (sometimes only 2) surgeries over the first few years of life. Eventually, the pulmonary arterial flow will be supplied through direct connections of the systemic venous flow to the pulmonary arteries, completely bypassing the heart. Stage 1 surgery (Norwood procedure for hypoplastic left heart syndrome, variations of this for other defects) has three goals: 1) Unobstructed systemic flow 2) Restricted pulmonary flow (why restricted?) 3) Unobstructed pulmonary venous flow Since we know that the systemic blood supply is more important and more difficult to surgically recreate, the great artery is committed to the systemic flow. Pulmonary flow is provided through a BTT shunt (the small size of the tube provides the needed restriction), and the atrial septum may need to be completely cut out to allow maximal mixing at the atrial level and minimal pulmonary venous obstruction. All of the systemic and pulmonary venous blood mix in the single ventricle before being pumped out of the heart. The pulmonary blood supply is rather tenuous as they are relying on a piece of Gore-tex that is 3 to 4 mm in diameter! Stage 2 surgery (Glenn procedure) is the first step in separating the two circulations. The SVC is detached from the RA and sewn directly to the right PA (why the right?), allowing the upper body systemic venous return to flow directly to the pulmonary arteries. This is a more secure source of pulmonary flow that will grow with the patient. Stage 3 surgery (Fontan procedure) is the third and final step in separating the systemic and pulmonary circulations. The IVC is detached from the RA and connected via a conduit to the pulmonary arteries. Now all systemic venous blood returns directly to the pulmonary arteries without a pump

Question 44

total anomalous pulmonary venous connection (return) (TAPVC) or (TAPVR)

Answer 44

1) No pulmonary veins connect with left atrium, but drain into systemic venous channels. 2) ASD is always present. 3) Partial forms may also occur. •This cyanotic lesions results from incomplete incorporation of the pulmonary veins into the LA. The heart starts with a primitive LA and the pulmonary veins grow from the lung buds towards the heart. The veins come together in a confluence and a common pulmonary vein develops and attaches to the LA. The common vein, pulmonary vein confluence and primitive LA then completely incorporate together to create a normal LA.

Question 45

pathophysiology of TAPVR

Answer 45

If there is a problem with the connection of the pulmonary venous confluence to the primitive LA, then the veins now have nowhere to drain. The body wants to keep blood moving, so a ‘pop-off’ vessel develops to decompress the pulmonary venous confluence and the pulmonary veins. This vessel typically goes one of three places: 1) Superiorly to the innominate vein 2) Inferiorly, through the diaphragm, to the IVC/hepatic veins 3) Infracardiac, to the coronary sinus Regardless of the direction, all of the pulmonary venous blood eventually gets to the right atrium and completely mixes with the systemic venous blood; saturations in all four heart chambers are the same. In order to have any cardiac output to the body, there has to be an ASD with obligate right to left shunting (why?). These infants will be cyanotic, but not necessarily in any distress. However, if the vein draining the pulmonary venous confluence is obstructed (the rule for veins that drain inferiorly), they can be extremely sick. There is typically no murmur associated with TAPVR at birth, although they may develop a relative PS murmur (systolic ejection at the left upper sternal border) from the volume overload in the right heart if diagnosed later.

Question 46

intervention for TAPVR

Answer 46

Obstructed TAPVR is one of the few pediatric cardiac surgical emergencies. If there is no obstruction, repair can be performed electively in the first 1 to 2 months of life. The back of the LA and the front of the pulmonary venous confluence are cut open and sewn together to create a complete LA. This is performed via median sternotomy on cardiopulmonary bypass. While this is typically a straightforward procedure with excellent results, repaired TAPVR is the most common cause of pulmonary vein obstruction.

Question 47

ToF

Answer 47

Answer 48

TGA

Question 49

Answer 49

TA repair

Question 50

Answer 50

TA

Question 51

Answer 51

tricuspid atresia

Question 52

Answer 52

tricuspid atresia

Question 53

Answer 53

Stage 1: Norwood

repair of tricuspid atresia

• Unobstructed systemic flow • Restricted pulmonary flow • Unobstructed pulmonary venous return

Question 54

Answer 54

Stage 2: Glenn

repair of tricuspid atresia

• Start to separate systemic and pulmonary venous blood and have upper extremity systemic venous blood go directly to the pulmonary arteries • Secure stable pulmonary blood supply that will grow with the patient

Question 55

Answer 55

Stage 3: Fontan

repair of tricuspid atresia

• Direct the remainder of systemic venous blood directly to the pulmonary arteries

Question 56

Answer 56

PDA

Question 57

Answer 57

ASD

Question 58

Answer 58

VSD

Question 59

Answer 59

AVSD

Question 60

Answer 60

TAPVR