Congenital heart disease Flashcards
What is the incidence and prevalence of ASD?
approximately 10 to 15 percent of congenital heart disease, with a reported birth prevalence of approximately 1 to 2 per 1000 live births
How are ASDs classified?
ASDs are classified based on their anatomic location, which generally reflects the abnormality of embryogenesis that led to the anomaly :
●Primum ASD
●Secundum ASD
●Sinus venosus ASD
●Coronary sinus ASD
Patent foramen ovale (PFO) is also an open communication between the right and left atria; however, a PFO is not considered an ASD, because no septal tissue is missing
Describe the development of the right atrial septum
The septation of the atria begins as early as the fifth week of gestation and involves three structures: septum primum, septum secundum, and the atrioventricular (AV) canal septum, which is made up in part by the superior and inferior endocardial cushion.
Describe the normal development of the atrial septum
- septation of the atria begins as early as the fifth week of gestation and involves three structures: septum primum, septum secundum, and the atrioventricular (AV) canal septum, which is made up in part by the superior and inferior endocardial cushion.
- The septum primum arises from the superior portion of the common atrium and grows caudally towards the AV canal septum (eg, the endocardial cushions) located between the atria and ventricles. The fusion between the septum primum and the endocardial cushions closes the orifice (ostium primum) separating the right and left atria.
- A second orifice (the ostium secundum) develops in the septum primum; this orifice is covered by the septum secundum that arises on the right atrial side of the septum primum. The septum secundum grows caudally and covers the ostium secundum forming the fossa ovalis. However, the septum secundum does not completely divide the atria in the fetus; it leaves an oval orifice (the foramen ovale) that is covered (but not sealed) on the left side by the flexible flap of the septum primum
Describe primum defects
The primum-type ASD develops if the septum primum does not fuse with the endocardial cushions, leaving a defect at the base of the interatrial septum that is usually large. This type of defect accounts for 15 to 20 percent of ASDs. Primum ASDs are usually not isolated, typically being associated with AV canal defects that include anomalies of the AV valves and ventricular septal defects
Describe secundum defects
Secundum ASDs are typically located within the fossa ovalis (remnant of the foramen ovale in the right atrium). This type of ASD can result from arrested growth of the secundum septum or excessive absorption of the primum septum. Multiple defects can be seen if the floor of the fossa ovalis is fenestrated. The defects vary greatly in size, from less than 3 mm to greater than 20 mm. Secundum ASDs typically present as an isolated cardiac defect, though they may be contiguous with other ASDs, such as a sinus venosus defect or a primum defect. Some patients with secundum ASD have functional mitral valve prolapse, perhaps related to a change in the left ventricular geometry associated with right ventricular volume overload.
Secundum defects account for approximately 70 percent of all ASDs and occur twice as often in females as in males. The familial recurrence rate has been estimated to be approximately 7 to 10 percent. In a comprehensive literature review, the median reported incidence was 5.64 per 10,000 live births. However, the true incidence of secundum ASD may be substantially higher because many ASDs are commonly undiagnosed in infancy and childhood, and spontaneously resolve.
What is Holt-Oram syndrome? What genetic mutation is most commonly involved?
autosomal dominant disorder characterized by upper limb defects (deformities of the radius, carpal bones, and/or thumbs) and cardiac septal defects, most commonly a secundum ASD. Cardiac conduction disturbances, including complete heart block, are also common.
Holt-Oram syndrome is genetically heterogeneous; mutations in the TBX5 gene are the most common cause.
What genes other than TBX 5 have been linked to familial isolated ASDs?
GATA4, MYH6, and NKX2-5
What congenital syndomes other than Holt-Oram syndrome are associated with secundum ASDs?
Noonan syndrome, Treacher Collins syndrome, and the thrombocytopenia-absent radii syndrome
Describe sinus venosus defects (ASDs)
Sinus venosus ASDs are characterized by malposition of the insertion of the superior or inferior vena cava straddling the atrial septum. The interatrial communication is within the mouth of the overriding vein and is outside the area of the fossa ovalis. Sinus venosus defects account for approximately 5 to 10 percent of ASDs.
Describe superior sinus venosus defects
●Superior sinus venosus defects (sometimes called superior vena caval defects) are located in the atrial septum immediately caudal to the orifice of the superior vena cava. The right upper lobe and middle lobe pulmonary veins often connect to the junction of the superior vena cava and right atrium, resulting in a partial anomalous pulmonary venous connection
Describe inferior sinus venosus defects
●Inferior sinus venosus defects, also known as inferior vena caval defects, are less common. They are located in the atrial septum immediately cranial to the orifice of the inferior vena cava. Inferior sinus venosus defects are often associated with partial anomalous connection of the right pulmonary veins.
Describe coronary sinus defects (ASDs)
In coronary sinus ASDs (unroofed coronary sinus), part or the entire common wall between the coronary sinus and the left atrium is absent. This rarer form accounts for less than 1 percent of all ASDs. Many such patients also have a persistent left superior vena cava.
Describe patent foramen ovale
PFOs are identified on autopsy in approximately 30 percent of the adult population. The size of a PFO can range from 1 to 10 mm in maximal potential diameter. A PFO is not considered an ASD, because no septal tissue is missing. Interatrial shunting generally does not occur as long as left atrial pressure exceeds right atrial pressure and the flap valve remnant of septum primum of the foramen ovale is competent. However, persistent left-to-right shunting frequently occurs in the first few weeks of life. Mild shunting during the neonatal period is common, particularly in premature infants, and is usually considered a normal finding.
What are some cardiovascular defects associated with ASDs?
ASDs are often associated with other congenital cardiac anomalies. Often the associated defect is clinically more important than the ASD itself. However, in some cases, the ASD may contribute substantially to the physiology of the condition. As examples, an ASD permits mixing between the pulmonary and systemic circulations in complete transposition of the great arteries, while in tricuspid atresia, the entire cardiac output passes across the ASD
How are ASDs classified according to size?
●Trivial – <3 mm in diameter
●Small – 3 to <6 mm in diameter
●Moderate – 6 to 8 mm in diameter
●Large – >8 mm in diameter
These absolute measurements are not exact and the relative size of the defect (related to overall heart size) may be more clinically relevant. For example, a 6 mm ASD would be insignificant in an adult but would be of moderate size in a newborn.
Describe the pathophysiology of ASDs with regards to perinatal physiology
In utero, pulmonary arterial blood flow in the fetus is limited by high pulmonary vascular resistance, which results in decreased right ventricular diastolic filling. Instead of traversing the tricuspid valve, much of the blood that flows into the right atrium is shunted across the isolated ASD into the left atrium, similar to the blood flow through the normal patent foramen ovale. At birth, left atrial pressure becomes greater than right atrial pressure, resulting in left-to-right shunting across the defect. Initially, the volume of blood shunted from left to right is small because the right ventricle is still relatively thick-walled and noncompliant. As the right ventricle remodels in response to the decreased pulmonary vascular resistance, its compliance increases and the mean right atrial pressure decreases. As a result, the left-to-right shunting increases in volume.
In some neonates, transient right-to-left shunting may also occur during the cardiac and respiratory cycles, resulting in mild cyanosis. In these patients, there is a drop in atrial pressure at the onset of ventricular contraction due to atrial relaxation that is more rapid in the left than the right atrium. During inspiration, the decrease in intrathoracic pressure results in an increase in systemic venous return and a decrease in pulmonary venous return, decreasing left atrial pressure and increasing right atrial pressure, which results in right-to-left shunting.
Describe the pathophysiology of ASDs with regards to postnatal physiology
With a small ASD, left atrial pressure is slightly higher than right atrial pressure, resulting in continuous flow of oxygenated blood from the left to the right atrium across the defect. The pressure gradient between the two atria and the amount of shunt flow depend upon the size of the defect and the relative distensibility of the right and left sides of the heart. Left-to-right shunting occurs primarily in late ventricular systole and early diastole, with some augmentation during atrial systole. Even when the right and left atrial pressures are equal, as will be seen with a large defect, left-to-right shunting still occurs because of the greater compliance of the right ventricle compared with the left ventricle.
The shunt flow consists of fully oxygenated blood from the left atrium, and constitutes a “useless circuit” of ineffective pulmonary blood flow through the right atrium and ventricle, pulmonary circulation, left atrium and back to the right atrium. Thus, the volume of blood flow in the pulmonary circulation is greater than that in the systemic circulation. The pulmonary flow to systemic flow ratio (Qp/Qs) can be over 3:1 in patients with large defects.
The increased flow leads to right-sided dilatation evident on chest radiograph and echocardiographic imaging. Right ventricular function is also occasionally decreased. The main pulmonary arteries dilate and the pulmonary vascularity is increased. These pulmonary vascular changes may be evident on the chest radiograph, and large vessels in both the lower and upper lobes may be seen.
The right-sided volume overload is usually well tolerated for years. Heart failure is unusual before age 30, but the prevalence increases substantially in older uncorrected patients over time. Other complications in older patients include atrial arrhythmias such as flutter and fibrillation, thought to result from chronic stretching of the atrial muscle and, occasionally, pulmonary arteriopathy leading to progressive pulmonary hypertension resulting in right-to left shunting of blood (ie, Eisenmenger syndrome).
Describe the likelihood of spontaneous closure of ASDs. What ASDs are unlikely to spontaneously close
Spontaneous closure is most likely to occur in patients with small secundum ASDs that are diagnosed during infancy or early childhood. Secundum defects of moderate and large size, types of ASDs other than secundum, and those that are detected later in childhood or adolescence are unlikely to close spontaneously, and some may increase in size over time
Describe the natural history of persistent moderate to large ASDs. What symptoms and signs may they have?
In patients with uncorrected moderate to large ASDs, left-to-right shunting may increase with age, leading to volume overload, heart failure, atrial arrhythmia, and/or pulmonary hypertension. Most patients become symptomatic before 40 years of age. Common symptoms include palpitations reflecting atrial arrhythmias (the most frequent presenting symptom), exercise intolerance, dyspnea, and fatigue. Arrhythmias are thought to result from stretching of the atria by the increased shunting. In some patients, exercise intolerance may develop as early as the second decade of life.
The right-sided volume overload associated with an ASD is usually well tolerated for years. Pulmonary vascular disease develops in approximately 10 percent of older patients with isolated ASDs, but this complication is rare in childhood and adolescence. Elevated pulmonary vascular resistance in infants with ASDs is almost always reversible with correction, unlike the rare complication of fixed pulmonary vascular disease seen in affected adults.
In uncorrected older patients, severe irreversible pulmonary hypertension (Eisenmenger syndrome) may develop and presents with signs of right ventricular failure resulting in right-to-left shunting. Clinical findings include cyanosis, dyspnea with exertion, hepatomegaly, and clubbing of the fingers and toes. These patients are also at risk for paradoxical embolization of clot from the venous system or right atrium via right-to-left shunting into the arterial system.
How might ASDs present overall? is paradoxical embolisation common?
Most ASDs are small and do not cause symptoms in infancy and childhood. They most commonly come to attention because a murmur is detected on physical examination or as an incidental finding on echocardiogram obtained for other reasons
Infants with large ASDs occasionally present with symptoms of heart failure, recurrent respiratory infections, or failure to thrive. Failure to thrive in infants with ASDs may be associated with extracardiac pathology
Paradoxical embolization and resultant embolic stroke is a rare complication of ASDs in pediatric patients
What might be seen on physical exam in ASD?
Depend on size of the defect, degree of shunting, and pulmonary arterial pressure. Characteristic findings include a midsystolic pulmonary flow or ejection murmur accompanied by a fixed split second heart sound (S2)
Describe the murmurs that may be heard with ASD
low velocity shunt flow across the ASD produces insufficient turbulence to be audible itself. However, several other murmurs may be heard
- A midsystolic pulmonary flow or ejection murmur, resulting from the increased blood flow across the pulmonic valve, is classically present with moderate to large left-to-right shunts and may be louder than that attributed to the usual functional murmur. This murmur is loudest over the second intercostal space and is usually not associated with a thrill. The presence of a thrill typically indicates a very large shunt or pulmonic stenosis.
- A murmur of mitral regurgitation may be heard and is due to a cleft mitral valve in ostium primum defects, and mitral valve prolapse in secundum defects. In the latter setting, an apical late or holosystolic murmur of mitral regurgitation radiating to the axilla may be heard.
- A middiastolic murmur of low to medium frequency due to high flow across the tricuspid valve may be heard with careful auscultation in patients with a left-to-right shunt greater than 2:1. A low-pitched diastolic murmur of pulmonic regurgitation may result from dilatation of the pulmonary artery.
Describe the classic S2 component of murmur in ASD
In contrast to the normal variation in S2 splitting during the respiratory cycle, patients with ASDs typically have a wide fixed split. The fixed split of S2 occurs because the atrial defect equalizes the respiratory effect on both right and left ventricular output. The widening of the split is due to prolonged emptying of the enlarged right ventricle which delays pulmonic closure. A relatively wide (though not fixed) S2 split is common in healthy individuals in the supine position. Therefore S2 should be evaluated in both the supine and sitting or standing position.
What signs of heart failure might be seen with ASDs?
In patients with large ASDs, signs of heart failure (eg, tachypnea, rales, failure to thrive, hepatomegaly) may be seen
What signs of right atrial enlargement might be seen in ASDs?
- A large left-to-right shunt may result in a precordial bulge due to atrial enlargement.
- In some, atrial enlargement leads to chest deformity with transverse depressions along the sixth and seventh costal cartilages at the site of attachment of the anterior part of the diaphragm, known as Harrison grooves.
- Patients with large left-to-right shunts also may have a hyperdynamic right ventricular impulse that results in a right ventricular heave. This is most pronounced along the left sternal border and in the subxiphoid area.
Can pulmonary hypertension occur in ASDs?
Pulmonary hypertension (PH) is unusual in pediatric patients with ASDs but can occur. Patients with PH usually have an accentuated pulmonic component of S2
What are some ECG findings in ASD?
- may be normal in a child with an uncomplicated ASD and a small shunt.
- moderate to large degree of shunting –> the QRS complex is often slightly prolonged and has a characteristic rSr’ or rsR’ pattern in V1 (often described as incomplete right bundle branch block). This pattern is thought to result from enlargement of the right ventricular outflow tract, which is the last portion of the ventricle to depolarize. Alternatively, it may result from stretching of peripheral specialized conduction fibers secondary to right ventricular outflow tract distension.
- Patients with increasing PH tend to lose the rSr’ and develop a tall monophasic R wave with a deeply inverted T wave.
- Notching of the peak of the R wave in the inferior leads (a pattern called “crochetage”) has been described in patients with an ASD.
What P wave changes might you see on ECG in ASD?
P wave is typically normal with secundum ASDs. In comparison, sinus venosus ASDs are often associated with a leftward frontal plane P wave axis (ie, negative in leads III and aVF, and positive in lead aVL). This leftward shift is caused by an ectopic pacemaker resulting from an ASD located near the sinus node. Right atrial enlargement may be reflected by increased P wave voltage. Sinus node dysfunction may develop in early childhood
What PR interval changes might you see on ECG in ASD?
The PR interval may be prolonged and increases with increasing age. First degree atrioventricular (AV) block can occur in any type of ASD but is classically present in ostium primum defects in association with complete right bundle branch block and left anterior fascicular block. The rim of the ostium primum defect is in close spatial relationship to the His bundle, accounting for abnormalities of impulse conduction through this area.
What QRS changes might you see on ECG in ASD?
The frontal plane QRS axis often ranges from +95° to +135° (right axis deviation) with a clockwise loop. Left axis deviation of the QRS axis with a counterclockwise frontal plane loop can occur with uncomplicated secundum ASD, although it usually suggests the presence of an AV canal defect.
What CXR findings might you see in patients with ASD?
- With small ASDs, the chest radiograph is typically normal.
- In patients with an isolated secundum ASD with a large left-to-right shunt, chest radiography findings include cardiac enlargement and increased pulmonary vascularity. The increase in pulmonary vascularity typically extends to the periphery of the lung fields, and the pulmonary trunk and central branches appear dilated. The heart often has a characteristic triangular appearance because the enlarged pulmonary arteries prevent the normal-diameter ascending and transverse aorta from forming the heart border. The right atrium and ventricle are usually enlarged, while the left atrium and left ventricle are normal.
Describe prenatal diagnosis of primum ASD
●Primum ASD – Prenatal ultrasounds by experienced fetal echocardiographers (Level III Fetal Ultrasound) can usually diagnose primum ASDs in the fetus at 18 to 22 weeks gestation. Advances in technology have enabled some specialized centers to identify primum ASDs in the first trimester, but the accuracy of detection remains low even in these centers.
Describe prenatal diagnosis of secundum ASD
●Secundum ASD – The more common secundum ASD cannot be reliably detected by fetal echocardiography, since the normal fetus has a sizable patent foramen ovale (PFO), and distinguishing between a small to moderate size secundum ASD and a PFO with right-to-left flow is usually not possible. However, the presence of very large secundum ASD may be suspected on fetal echocardiography but must be confirmed by postnatal echocardiograms.
Describe the prenatal diagnosis of sinus venosus and coronary sinus ASDs
●Sinus venosus and coronary sinus ASDs – Experienced fetal echocardiographers may be able to detect sinus venosus ASDs and coronary sinus ASDs. However, the sensitivity and specificity of fetal ultrasound for identification of these more unusual types of atrial septal defect is not known.
Describe the postnatal diagnosis of ASDs
An isolated ASD may be clinically suspected based upon findings on physical examination (midsystolic pulmonary flow or ejection murmur and fixed splitting of the second heart sound and electrocardiogram (incomplete right bundle branch block. The diagnosis is confirmed by echocardiography.
What is the role of echo in ASD diagnosis. Compare and contrast TTE vs. TOE
test of choice for the diagnosis of ASD. Transthoracic echocardiography (TTE) is usually definitive in diagnosing secundum ASDs. Shunt volume, shunt ratios, and pulmonary artery pressures can be estimated with Doppler flow echocardiography
Although TTE is usually adequate to identify the presence of an ASD and determine its overall size, transesophageal echocardiography (TEE) is often necessary to precisely measure ASD margins at the time of catheter closure of secundum ASDs. TEE is generally superior to TTE in measuring the size and position of ASDs, diagnosing sinus venosus defects (image 5), and assessing for other abnormalities such as anomalous venous connection.
In addition, TEE more precisely measures ASD margins and, on occasion, may determine that the ASD rims are inadequate for catheter device closure.
Finally, not all patients have good acoustic windows for adequate TTE visualization. False dropout of the thin fossa ovalis region of the atrial septum can occur even in childhood. Thus, TEE prior to planned surgical or percutaneous closure can provide an additional level of diagnostic assurance and sometimes prevent unnecessary therapeutic procedures.
What is the role of MRI in diagnosing ASD?
Magnetic resonance imaging (MRI) can be helpful in selected cases with suspected associated defects such as partial anomalous pulmonary venous connection or in patients in whom there are inconclusive echocardiographic findings. MRI can also provide accurate quantitation of ventricular volumes, and of pulmonary and systemic flow when this information is required
What is the differential diagnosis of ASDs?
The differential diagnosis of isolated ASDs includes other cardiac conditions that present as an incidental finding of a cardiac murmur in asymptomatic children. Although other physical findings (eg, fixed second heart sound) and electrocardiographic findings of incomplete right bundle branch block suggest ASD, echocardiography conclusively distinguishes these conditions from ASD.
●Pulmonic stenosis
●Innocent or functional murmurs
●Aortic stenosis
●Ventricular septal defect
●Patent ductus arteriosus
●Mitral stenosis
Describe the physiology of the foramen ovale
In the fetus, the foramen ovale is held open by the pressure gradient between the right and left atria. Right atrial pressure is higher than that on the left and pushes the flexible septum primum aside, permitting right to left flow of oxygenated blood from the inferior vena cava into the left ventricle. At birth, expansion of the lungs lowers right heart pressures at the same time that systemic vascular resistance rises, causing reversal of the atrial gradient. The septum primum is then held against the septum secundum and the interatrial shunt ceases.
In approximately 70 percent of individuals, the septum primum and septum secundum fuse during infancy or early childhood, creating an intact interatrial septum; the remnant of the foramen ovale in the right atrium is termed the fossa ovalis. However, in a significant minority of the population, the septae do not fuse. If the foramen ovale is completely covered, but not sealed, it is called a PFO, indicating that the foramen can be opened (by a reversal of the interatrial pressure gradient or by an intracardiac catheter)
What factors impact the functional consequences of ASDs?
- anatomic location of the defect
- size
- presence or absence of other cardiac anomalies
- systolic and diastolic function of the ventricles
What are some important consideration when managing a child with an isolated ASD?
●Size, degree of shunting, and persistence of the ASD
●Likelihood of spontaneous closure
●When closure is indicated, deciding between surgical and percutaneous transcatheter closure
Describe measurement of shunt ratio and how this is important in managing ASD patient
The main indication for ASD closure has been the presence of a left-to-right shunt sizable enough to result in clinically significant right heart overload. This typically occurs in patients with moderate to large ASDs. The usual clinical standard for repair is a measured shunt ratio of pulmonary to systemic flow (Qp/Qs) >2:1, though high quality evidence supporting this threshold is generally lacking. Other experts in the field have advocated lower thresholds of 1.7:1 and 1.5:1
How do you measure shunt ratio?
- Cardiac catheterization is considered the gold standard for measuring Qp/Qs
- Phase contrast magnetic resonance imaging (MRI) in experienced hands appears to be at least as good as the standard Fick technique for measuring shunt flow with blood samples obtained at catheterization
- Pulsed Doppler echocardiography is now routinely used in sites that have established an acceptable correlation between echocardiographic and catheterization laboratory or MRI estimates of shunt flow.
- Because echocardiography and MRI are noninvasive, these techniques easily permit serial monitoring.
How do you manage ASD if Qp/Qs isnt available?
- echocardiographic evidence of substantial right heart enlargement
- qualitative color and spectral Doppler findings of a large amount of left-to-right shunting through the ASD, can be sufficient to justify ASD closure. In addition, the following findings support ASD closure, though these are not sufficient in isolation:
●Evidence of right ventricular hypertrophy on electrocardiogram
●Auscultatory finding of a tricuspid flow rumble by an experienced clinician
●Increased heart size and pulmonary vascularity on chest radiograph
Do small isolated secundum ASDs close? When? Should these defects be closed?
- majority of isolated small secundum ASDs close spontaneously by two years, and some as late as five years of age
- in the absence of associated symptoms, early closure is not indicated for these defects
because there is a a small possibilityof spontaneous closure during the first two years of life, intervention to close even moderate and large isolated secundum ASDs is generally deferred until after the age of two years in asymptomatic patients
What types of ASDs are unlikely to close spontaneously?
- Secundum defects of moderate and large size
- types of ASDs other than secundum
Should small persistent ASDs w/o symptoms be closed?
- do not suggest closure.
- evidence supporting a benefit of ASD closure in this setting is generally lacking.
- risk of paradoxical embolism through a small ASD or valve-competent patent foramen ovale (PFO) is uncertain.
- The benefit of ASD closure in reducing the risk of embolism must be weighed against the short- and long-term risks of the procedure for closure. Procedure risks are changing as closure techniques continue to improve with decreasing morbidity.
- Closure is recommended by many clinicians in older adult patients with a small ASD or PFO who have experienced embolic strokes or transient ischemic attacks
When is closure of ASDs typically recommended?
In patients with a persistent moderate or larger defect, left-to-right shunting usually increases with age if the defect is not corrected. In these patients, we recommend closure if there is significant shunting
How do we differentiate between ASD and PFO?
- presence or absence of a tissue flap partially occluding the opening of the atrial septum. Openings with a tissue flap are defined as PFO, and those without a tissue flap are defined as secundum ASD.
- defect size or position in the atrial septum to differentiate between ASD and PFO. Caution should be employed when using absolute defect diameter for classification in premature infants, because the physiologic effect of defect size varies with patient size.
Because of the lack of uniformity in subjective interpretations of echocardiograms, and because pediatric cardiology practice standards differ, primary care clinicians should seek pediatric cardiology advice regarding the necessity for follow-up when receiving an echocardiographic report identifying an ASD or a borderline classification such as “PFO/ASD.”
Does PFO need to be followed up?
- follow-up is generally not necessary.
- medical follow-up of asymptomatic patients with PFO does not appear to have any benefit.
- Many PFOs spontaneously close during childhood and adolescence, and most of the PFOs that persist into adulthood never cause problems.
- Requiring routine follow-up for such children may cause undue anxiety regarding rare complications that can be associated with PFO later in adulthood (eg, paradoxical embolus and decompression illness).
- Furthermore, given the high prevalence of PFO, medical follow-up of all PFOs would be burdensome on a population basis.
Do trivial ASDs need to be followed up? What defines a trivial ASD?
children with trivial secundum ASDs (<3 mm) do not require specific follow-up.
Which ASDs require follow-up?
- The child in whom a clinically significant ASD is detected should be followed regularly by a pediatric cardiologist.
- Clinically significant ASDs include:
- secundum ASDs with a maximal diameter of ≥3 mm, since secundum ASDs of this size can increase substantially with patient growth
What examination and investigations are performed when following up ASD patients?
detecting any signs or symptoms of increased shunting. Signs suggestive of increased shunting include:
- failure to gain weight appropriately
- increased frequency of respiratory infections
- signs of heart failure such as hepatomegaly or auscultatory evidence of pulmonary congestion
Echocardiography is indicated when there is concern that the shunt may be increasing or to confirm spontaneous closure.
When is ASD closure recommened (clinical indications)?
- right heart enlargement
- pulmonary overcirculation
- evidence of substantial left-to-right shunting through an ASD (ie, ratio of pulmonary to systemic flow [Qp/Qs] >2:1 or other evidence of large amount of left-to-right shunting)
These findings are typically associated with moderate to large ASDs. Such defects are unlikely to close spontaneously, and observational data suggest that left-to-right shunting may increase with age, resulting in heart failure, exercise intolerance, and increased risk of arrhythmia and pulmonary hypertension
ASD closure is generally deferred until after the age of two years in asymptomatic patients because there is a possibility, albeit small, of spontaneous closure during the first two years of life
Is there benefit in closing persistent ASD without significant L-R shunt?
- no definitive evidence that ASD closure is beneficial for patients with a persistent ASD without a significant left-to-right shunt and without symptoms directly attributable to the ASD (including paradoxical embolism or platypnea-orthodeoxia, which is shortness of breath and hypoxemia that occurs when sitting or standing and that is relieved when lying down).
- Most pathologic consequences of ASD, such as atrial arrhythmias and (rarely) pulmonary hypertension, are secondary to right heart volume overload or pulmonary overcirculation.
- No studies have shown that prospective closure of asymptomatic small ASDs prevents paradoxical embolization, and the risk of endocarditis with isolated small ASDs appears to be negligible. Since all closure techniques have risk, closure of asymptomatic small ASDs does not appear to be warranted at this time.
Describe the aims of preprocedure echo evaluation for ASD
●Accurately measuring the size of the defect and degree of left-to-right shunting
●Identifying other cardiac defects
●Assessing for pulmonary hypertension
The preprocedural echocardiogram helps to determine the optimal choice of intervention. For example, severe fixed pulmonary hypertension is a contraindication for ASD closure, though this is a rare finding in children with ASDs.
Describe indications for percutaneous closure for ASDs
- usually possible for secundum ASDs that are not excessively large (ie, <30 mm in diameter) and with a rim of tissue around the defect sufficient for effective closure without obstruction or impingement on adjacent cardiac structures (at least 5 mm). For patients with secundum ASDs that meet these criteria, suggest percutaneous closure rather than surgical closure.
- Percutaneous closure should not be used in sinus venosus, primum or coronary sinus ASD, or in infants with large defects and heart failure.
- Although successful percutaneous closure can be performed in young infants, the complication rate appears to be higher in infants and young children, compared with older patients in the three- to five-year age range who weigh at least 15 kg.
- Furthermore, spontaneous closure of even large ASDs can occur in infants and young children. As a result, the benefits of closure in infants and young children (weight <15 kg) must be weighed against the increased risk of complication and possibility of spontaneous closure.
Surgical closure is reserved for all other patients or based on family preference.
Describe overall post-procedure care in ASD
- Clinical evaluation subsequent to closure should assess for signs of embolic events, arrhythmia, and chest pain.
- Echocardiographic surveillance is essential to detect complications including:
- residual shunting
- pericardial effusion
- ventricular function
- pulmonary artery pressure
- in patients who underwent percutaneous device closure, device migration, and thrombosis.
Electrocardiographic monitoring is also performed to detect any evidence of atrial arrhythmia.
Describe post-procedure care following percutaneous ASD closure
Patients are typically treated with aspirin, clopidogrel, or another anticoagulant agent subsequent to percutaneous ASD defect closure for six months to reduce the chance of thrombus formation on the ASD device before the device has become endothelialized.
In addition, temporary limitations on highly vigorous physical activity during the weeks immediately subsequent to ASD device implantation are usually advised. Specific recommendations on such temporary exercise limitations vary among interventional cardiologists.
Describe post-procedure care for surgical ASD closure
In the immediate postoperative period, patients are monitored for complications including:
- pericardial and pleural effusions
- postpericardiotomy syndrome.
- Fevers, chest pain, abdominal pain, and vomiting in postoperative ASD patients suggest the possible presence of clinically significant effusions and/or postpericardiotomy syndrome.
Percutaneous closure of ASD should not be used in patients with…?
- sinus venosus ASD
- primum ASD
- coronary sinus ASD
- infants with large defects and heart failure.
Periprocedural complications associated with percutaneous ASD closure include…?
device embolization or malposition, and arrhythmias (usually atrial)
What are indications for surgical correction of ASDs?
- sinus venosus defects
- coronary sinus defects
- primum ASDs
- complex congenital lesions including partial anomalous pulmonary venous connection
- infants with large secundum defects who present with heart failure generally cannot be adequately treated with percutaneous closure and typically undergo surgical correction
What are some post-op complications of ASD closure?
Postoperative complications occur in 25 to 30 percent of patients and include:
●Pericardial effusion
●Pleural effusions
●Arrhythmias
●Bleeding
●Pneumothorax
●Wound infection
Complications are usually transient and often do not require intervention. They may occur because of the standard surgical technique, which requires sternotomy or thoracotomy, atriotomy, and cardiopulmonary bypass, with its potentially deleterious consequences.
What is the typical overall outcome in surgical correction for ASD?
Outcomes following surgical closure of ASD in childhood are excellent with almost no difference in long-term mortality compared with age-matched controls. Long-term morbidities such as stroke, heart failure, arrhythmia, heart block, and pulmonary hypertension are also rare
Percutaneous vs. surgical correction? Differences in outcome and need for reintervention?
Observational data suggest that procedural success rates are similarly high for both surgery and percutaneous closure, but complication rates and length of hospital stay are lower with the percutaneous approach. There may be a slightly increased risk of needing reintervention with percutaneous closure.
Long-term cardiology follow-up is indicated following surgical or percutaneous ASD closure if there are…?
- other cardiac lesions
- preoperative or postoperative atrial arrhythmias
- if the patient had pulmonary artery hypertension preoperatively
- ASD was repaired during adulthood.
Describe the long term management of surgically closed ASDs
Patients who have had ASDs surgically repaired during childhood and who have uncomplicated early postoperative courses generally are free of late complications and activity restrictions. Patients with surgically repaired ASDs are at increased risk of developing late atrial arrhythmias compared with the general population. Routine surveillance is generally not necessary since the incidence is relatively low overall and the nature of these atrial arrhythmias is typically benign
Describe the long term follow up of percutaneously closed ASDs
Long-term outcomes following percutaneous ASD closure are less certain, and generally follow these children longitudinally.
Describe long term guidelines for sport participation in children with ASDs
●Patients with untreated ASDs and normal pulmonary pressure can participate in all competitive sports.
●Patients with untreated ASDs and pulmonary hypertension may participate in low-intensity (class IA) sports.
●Patients with untreated ASDs and associated pulmonary vascular obstructive disease with cyanosis and large right-to-left shunt should be restricted from participation in all competitive sports.
●Patients with repaired ASD can participate in all competitive sports three to six months after closure if they have normal pulmonary pressure and ventricular function, and no arrhythmias.
When is endocarditis prophylaxis recommened in children with isolated ASD?
The 2007 guidelines of the AHA recommend no antibiotic prophylaxis in children with an isolated ASD, except in the following circumstances:
●In children with a repaired ASD which required the use of prosthetic material or device, prophylactic antibiotics are recommended for dental and respiratory tract procedures during the first six months after the repair.
●In children with repaired ASD with a residual defect at the site or adjacent to the site of a prosthetic device, antibiotic prophylaxis is recommended for dental and respiratory tract procedures
Isolated secundum defects account for what percentage of CHD?
7%
What part of the artrial septum can ASDs occur?
any part of atrial septum - secundum, primum, or sinus venosus
What are the five most common congenital heart lesions and what percentage of total do they each make?
VSD 30-35%
ASD (secundum) 6-8 %
PDA 6-8%
Coarctation of aorta 5-7%
TOF 5-7%
What chromosome location, gene and cardiac defect is associated with Digeorge syndrome (velocardiofacial syndrome)?
22q11.2, 11p13p14
TBX1
TOF, IAA, TA, VSD
What chromosome location, gene and cardiac defect is associated with familial ASD with heart block?
5q35
NKX2.5
ASD, heart block
What chromosome location, gene and cardiac defect is associated with familial ASD without heart block?
8p22-23
GATA4
ASD
What chromosome location, gene and cardiac defect is associated with Alagille syndrome (bile duct hypoplasia etc.)
20p12, 1p12
JAGGED1, NOTCH2
Peripheral pulmonary hypoplasia, PS, TOF
What chromosome location, gene and cardiac defect is associated with Holt Oram syndrome (limb defects etc.)
12q24
TBX5
ASD, VSD, PDA
What chromosome location, gene and cardiac defect is associated with trisomy 21 (Down syndrome)?
21q22
Not known
AVSD
What chromosome location, gene and cardiac defect is associated with isolated familial AV septal defect (without trisomy 21)?
1p31-p21, 3p25
CRELD1
AVSD
What chromosome location, gene and cardiac defect is associated with Familial TAPVR?
4p13-q12
Not known
TAPVR
What chromosome location, gene and cardiac defect is associated with Noonan syndrome?
Multiple
PTPN11, KRAS, SOS1, SOS2, RAF1, BRAF, MEK1, HRAS, NRAS, SHOC2, CBL, NF1
PS, ASD, VSD, PDA, Hypertrophic cardiomyopathy
What chromosome location, gene and cardiac defect is associated with Ellis-van Creveld syndrome (polydactyly)
4p16
ECV, EVC2
ASD, common atrium
What chromosome location, gene and cardiac defect is associated with Char syndrome (craniofacial, limb defects etc)?
6p12-21.5
TFAP2B
PDA
What chromosome location, gene and cardiac defect is associated with Williams-Beuren syndrome?
7q11.23
ELN (Elastin)
Supravalvular AS, peripheral PS
What chromosome location, gene and cardiac defect is associated with Marfan syndrome?
15q11
Fibrillin
Aortic aneurysm, mitral valve disease
What chromosome location, gene and cardiac defect is associated with familial laterality abn?
Xq24-2q7, 1q42, 9p13-21
ZIC3, DNAI1
Situs inversus, complex congenital heart disease
What chromosome location, gene and cardiac defect is associated with Turner syndrome
X
Not known
Corctation of the aorta, aortic stenosis
What chromosome location, gene and cardiac defect is associated with Trisomy 13 (Patau)
13
Not known
ASD, VSD, PDA, valve abn
What chromosome location, gene and cardiac defect is associated with Trisomy 18 (edward)
18
Not known
ASD, VSD, PDA, valve abn
What chromosome location, gene and cardiac defect is associated with Cri du chat syndrome?
5p15.2
CTNND2
ASD, VSD, PDA, TOF
What chromosome location, gene and cardiac defect is associated with cat-eye syndrome?
22q11
Not known
TAPVR, TOF
What chromosome location, gene and cardiac defect is associated with Jacobson syndrome?
11q23
JAM3
HLHS
What chromosome location, gene and cardiac defect is associated with Costello syndrome?
11p15.5
HRAS
PS, hypertrophic cardiomyopathy, arrhythmias
What chromosome location, gene and cardiac defect is associated with CHARGE syndrome?
8p12, 7q21.11
CHD7, SEMA3E
ASD, VSD, TOF
What chromosome location, gene and cardiac defect is associated with Kabuki syndrome
12q13.12
MILL2
ASD, VSD, TOF, coarctation, TGA
What chromosome location, gene and cardiac defect is associated with Carney syndrome?
2p16
PRKAR1A
Atrial; and ventricular myxomas
What is the most common cardiac malformation and what percentage of congenital heart disease does it account for?
VSD. 25% of congenital heart disease
What is the most common type of VSD.
Membranous type. These defects are in a posterio-inferior position, anterior to the septal leaflet of the tricuspid valve.
VSDs between the crista supventricularis and the papillary muscle of the conus may be associated with…?
pulmonary stenosis and other manifestation of TOF
Supracristal VSDs are how common and where are they found?
less common. found just beneath the pulmonary valve and may impinge on an aortic sinus and cause aortic insufficiency
What race are supracristal VSDs are common in?
Asian
What is the major determinant of size of L-R shunting with VSD?
Physical size of VSD
In large defect VSDs, what is the major determinant of shunt magnitude?
Level of pulmonary vascular resistance in relation to systemic vascular resistance is the major determinant of shunt magnitude
What pressure differences are noted in the LV vs. RV in pressure restrictive VSDs?
In small communications (usually <5mm), VSD is deemed pressure restrictive, meaning that RV pressure is normal or only slightly elevated. The higher pressure in the left ventricle drives the shunt left to right, and the size of the defect limits the magnitude of the shunt
What pressure changes in LV and RV are noted in nonrestrictive VSDs?
In larger, nonrestrictive VSDs (usually >10mm), RV and LV pressure are equalised. In these defects the direction of shunting and shunt magnitude are determined by PVR/SVR ratio
What is the typical murmur feature in VSDs?
Loud, harsh, or blowing holosystolic murmur is presented and heard best over the left lower sternal border, frequently accompanied by a thrill. In a few cases the murmur ends before the second heart sounds (S2), presumably because of closure of the defect during late systole
How might a VSD present in a neonate?
Short, loud, harsh, systolic murmur over the apex –> tiny VSD in the apical muscular septum
In premature infants the murmur may be heard earlier as PVR descreases more rapidly
How do large VSDs present?
Excessive pulm BF and PHTN –> signs of CHF such as dyspnea, poor feeding, poor growth, profuse perspiration, recurrent pulm infections in infancy.
Cyanosis often absent, but duskiness is sometimes noted during infections or crying
Prominent L precordium, palpable parasternal lift, laterally displaced apical impulse and apical thrust, systolic thrill
Holosystolic murmur of large VSD is less harsh than that of a small VSD and more blowing in nature due to lack of significant pressure gradient
Pulmonic component of S2 may be increased as a result of PHTN
Mid-diastolic, low-pitched rumble at apex is caused by inc BF across the MV and usually indicates a Qp:Qs ration of > 2:1
CXR findings for VSD?
Small VSD: usually normal, but minimal cardiomegaly and a borderline inc in pulmonary vasculature may be observed
Large VSD: cardiomegaly w/ prominence of both ventricles, L atrium and pulm artery. pulm vasc markings are inc, and frank pulm oedema, including pleural effusions, may be present
ECG findings for VSD?
Small VSD: generally normal but may suggest LV hypertrophy. RV hypertrophy is sign that defect is not small and that pt has pulm HTN or an associated lesion such as pulmonic stenosis
Large VSD: biventricular hypertrophy; P waves may be notched (indicating LA enlargement)
Normal right-sided heart pressure and PVR are seen in?
Small, restrictive VSDs
Describe the physiology of a large VSD
What pertentage of all VSDs do supracristal VSDs make?
Supracristal VSDs are more common in what demographic group?
Although supracristal VSD accounts for about 5% of all pts with VSD, the incidence is higher in asian children and in males
Describe the heart failure that can occur in supracristal VSDs
HF 2ndry to large L-R shunt rarely occurs, but w/o surgery, moderate-severe aortic insufficiency and LV failure can occur
Describe the types of coarctation of the aorta?
Can occur as discrete juxtaductal obstruction or as tubular hypoplasia of the transverse aorta starting at one of the head of neck vessels and extending to the ductal area (prevously referred to as preductal or intantile-type coarctation
Often both components are present
Describe the pathophysiology of coarctation of the aorta
may be initiated in fetal life by presence of a cardiac abn that results in dec blood flow anterograde through the aortic valve (e.g. bicuspid aortic valve, VSD). Alternatively, coarctation may be caused by abn extension of contractile ductal tissue into the aortic wall
Discrete juxtaductal coarctation - ascending aortic blood flows through the narrowed segment to reach the descending aorta, although LV HTN and hypertrophy result
1st few days of life, PDA may serve to widen the juxtaductal area of the aorta and provide temporary relief from obstruction. Net L-R shunting occurs in these acyanotic infants
with more-severe juxtaductal coarctation or in the presence of transverse arch hypoplasia, RV blood is ejected through the ductus to supply the descending aorta
perfusion of the lower part of the body is then dependent on RV output - in this situation femoral pulses are palpable and differential BPs may not be helpful in making the diagnosis
What imaging modality is preferred to diagnose coarctation of the aorta?
Segment of coarctation can generally be visualised by 2D echo
assoc anomalies of the MV and aortic valve can also be demonstrated
The descending aorta is hypopulsatile
color doppler is useful for demonstating the specific site of the obstruction
pulsed and continuous wave doppler studies determine the pressure gradient directly at the area of coarctation; in the presence of a PDA the severity of the narrowing may be underestimated
if echo equivocal - CT and MRI can be used
CT, MRI or diagnostic catheterisation is not needed before surgery in cases well defined by echo
Describe the pathophysiology of pulmonary stenosis?
Obstructed RV outflow –> inc RV systolic pressure and wall stress –> hypertrophy of the RV
severity of abn depend on size of restricted valve opening
Severe cases - RV pressure may be high than systemic arterial systolic pressure
PAP is normal or decreased
Arterial O2 sats will be normal even in severe stenosis, unless an intracardiac communicaiton such as VSD or ASD allows blood to shunt from right to left
severe PS in neonates –> dev RV complicance often leads to cyanosis as a result of R-L shunt through a PFO, a condition termed critical pulmonic stenosis
Describe the different anatomic subtypes of PS?
Describe the abn associated with TOF?
The original description of TOF included the following four abnormalities: a large VSD, RVOT obstruction, RVH, and overriding of the aorta. In actuality, only two abnormali-
ties are required, a VSD large enough to equalize pressures in both ventricles and an RVOT obstruction. The RVH is secondary to the RVOT obstruction, and the overriding of the aorta varies
CXR findings in cyanotic TOF?
- The heart size is normal or smaller than normal, and pulmonary vascular markings are decreased. “Black” lung fields are seen in TOF with pulmonary atresia.
- A concave main PA segment with an upturned apex (i.e., “boot-shaped” heart or coeur en sabot) is characteristic
- RA enlargement (25%) and right aortic arch (25%) may be present.
Echo findings in TOF?
- A large, perimembranous infundibular VSD and overriding of the aorta are readily imaged in the parasternal long-axis view
- Anatomy of the RVOT, the pulmonary valve, the pulmonary annulus, and the main PA and its branches is imaged in the parasternal short-axis and subcostal short-axis views. These views allow systematic evaluation of the severity of obstruction at different levels.
- Doppler studies estimate the pressure gradient across the RVOT obstruction.
- Anomalous coronary artery distribution can be imaged accurately by echocardiographic studies. The major concern is to rule out any branch of the coronary artery crossing the RVOT. Thus, preoperative cardiac catheterization solely for the diagnosis of coronary artery anatomy is not necessary.
- Associated anomalies such as ASD and persistence of the left superior vena cava (LSVC) can be imaged.
When would a shunt operation be chosen rather than primary repair in TOF pts?
Many institutions prefer primary repair without a shunt operation regardless of the patient’s age. However, when
the following situations are present, a shunt operation may be chosen rather than primary repair:
- Neonates with TOF and pulmonary atresia
- Infants with hypoplastic pulmonary annulus, which requires a transannular patch for complete repair
- Children with hypoplastic PAs
- Unfavorable coronary artery anatomy
- Infants younger than 3 to 4 months old who have medically unmanageable hypoxic spells
- Infants weighing less than 2.5 kg
What primary surgical operation are often performed in TOF?
Although several other procedures were performed in the past, a modified BT (Gore-Tex interposition) shunt is the only procedure performed at this time.
- Classic BT shunt, anastomosed between the subclavian artery and the ipsilateral PA, is usually performed for infants older than 3 months because the shunt is often thrombosed in young infants. A right-sided shunt is performed in patients with left aortic arch; a left-sided shunt is performed for right aortic arch.
- With a modified BT shunt, a Gore-Tex interposition shunt is placed between the subclavian artery and the ipsilateral PA. This is the most popular procedure for any age, especially for infants younger than 3 months of age. Whereas a left-sided shunt is preferred for patients with left aortic arch, a right-sided shunt is preferred for patients with a right aortic arch. The surgical mortality rate is 1% or less.
- The Waterston shunt, anastomosed between the ascending aorta and the right PA, is no longer performed because of a high incidence of surgical complications. Complications resulting from this procedure included too large a shunt leading to CHF or pulmonary hypertension and narrowing and kinking of the right PA at the site of the anastomosis. This created difficult problems in closing the shunt and reconstructing the right PA at the time of corrective surgery.
- The Potts operation, anastomosed between the descending aorta and the left PA, is no longer performed either. It may result in heart failure or pulmonary hypertension, as in
the Waterston operation. A separate incision (i.e., left thoracotomy) is required to close the shunt during corrective surgery, which is performed through a midsternal incision
Physical exam findings in TGA?
- Moderate to severe cyanosis is present, especially in large male newborns. Such an infant is tachypneic but without retraction unless CHF supervenes.
- The S2 is single and loud. No heart murmur is heard in infants with an intact ventricular septum. An early or holosystolic murmur of VSD may be audible in less cyanotic
infants with associated VSD. A soft midsystolic murmur of PS (LVOT obstruction) may be audible. - If CHF supervenes, hepatomegaly and dyspnea develop.
ECG findings in TGA?
- Right ventricular hypertrophy (RVH) is usually present after the first few days of life. The QRS voltages and the QRS axis may be normal in many newborns with the defect. After 3 days of life, an upright T wave in V1 may be the only abnormality suggestive of RVH
- Biventricular hypertrophy (BVH) may be present in infants with large VSD, PDA, or pulmonary vascular obstructive disease because all of these conditions produce an addi-
tional left ventricular hypertrophy (LVH). - Occasionally, right atrial hypertrophy (RAH) is present.
CXR findings in TGA?
- Cardiomegaly with increased pulmonary vascularity is typically present.
- An egg-shaped cardiac silhouette with a narrow, superior mediastinum is characteristic
Echo findings in TGA?
- In the parasternal long-axis view, the great artery arising from the posterior ventricle (LV) has a sharp posterior angulation toward the lungs, which suggests that this artery
is the PA. In contrast to the normal intertwining of the great arteries, the proximal portion of the great arteries runs parallel. Unlike in a normal heart, there is a fibrous continuity between the pulmonary and mitral valves, and subaortic conus is present. (In normal hearts, there is aortic–mitral fibrous continuity with subpulmonary conus.) - In the parasternal short-axis view, the “circle and sausage” appearance of the normal great arteries is not visible. Instead, the great arteries appear as “double circles”. The PA is in the center of the heart, and the coronary arteries do not arise from this great artery. The aorta is usually anterior and slightly to the right of the PA, and the coronary arteries arise from the aorta.
- In the apical and subcostal five-chamber views, the PA (i.e., the artery that bifurcates) is seen to arise from the LV, and the aorta arises from the RV.
- The status of atrial communication, both before and after balloon septostomy, is best evaluated in the subcostal view. Doppler examination and color-flow mapping should aid in the functional evaluation of the atrial shunt.
- Frequently, associated defects such as VSD, LVOT obstruction (dynamic or fixed), or pulmonary valve stenosis are found. Subaortic stenosis or COA rarely occurs.
- The coronary arteries can be imaged in most patients in the parasternal and apical views
Describe the overall surgical approaches to TGA?
Palliative Procedure. No palliative procedure is performed unless an arterial switch operation (ASO) cannot be performed early in life.
Definitive Repair. Historically, definitive surgeries performed for TGA were procedures that switched right- and left-sided blood at three levels: the atrial level (intraatrial repair surgeries such as the Senning or Mustard operation), the ventricular level (i.e., Rastelli operation), and the great artery level (ASO). At this time, ASO is clearly the procedure of choice, and intraatrial repair surgeries are very rarely performed only under unusual
situations. The Damus-Kaye-Stansel operation in conjunction with the Rastelli operation can be performed in patients with VSD and subaortic stenosis. Because of a relatively poor
long-term result of the Rastelli operation, other options such as the Nikaidoh operation or REV (réparation à I’étage ventriculare) procedure have become more popular recently
