Congenital Cardiac Anomalies Flashcards
(44 cards)
What is the incidence of congenital heart disease?
There are approximately 9 new cases of congenital heart disease per 1000 live
births annually and this number is relatively constant around the world.
When does the heart develop?
Cells in the lateral mesoderm begin to differentiate into pre-cardiac cells early in the 3rd week of gestation. After a complex process of folding and spiraling, cardiac development is essentially complete by about 7 weeks gestation.
What are the 3 physiologic fetal shunts?
The ductus venosus, foramen ovale and ductus arteriosus are the 3 fetal shunts that help facilitate the streaming of oxygenated placental blood to the cerebral and cor- onary circulation and deoxygenated blood to the lower body, viscera and placenta for re-oxygenation.
What factors affect ductal (arteriosus) patency?
In the fetus, ductal patency is maintained by low oxygen saturation and high levels of circulating prostaglandins.
After birth, the rise in oxygen saturation inhibits prostaglandin synthase resulting in a decreased level of prostaglandin.
COX-2 inhibition (NSAIDs) can cause ductal constriction.
When is ligation of a patent ductus arteriosus (PDA) indicated in pre-term infants?
For pre-term infants, closure is indicated in a hemodynamically significant PDA.
Hemodynamic significance is demonstrated by excessive left to right ductal flow resulting in too much blood flow to the lungs and too little blood flow to the body.
Unless contraindicated, NSAID trials are attempted prior to surgical ligation.
What are important anatomic landmarks to identify a ductus arteriosus?
After left posterolateral thoracotomy, the 3rd or 4th interspace is entered and the lung is retracted anteriorly and inferiorly. Once the phrenic and left recurrent laryngeal nerves are identified, enough pleura is opened to clearly identify the left subclavian artery, distal aortic arch, descending aorta and PDA. The PDA may be safely ligated about 1 to 2 mm from its aortic end at that time [3].
What hemodynamic changes should occur after a PDA is ligated?
A rise in systemic blood pressure—diastolic greater than systolic—should be seen [4]. 8.
What are the commonly seen and described vascular rings?
The complete vascular rings are: double aortic arch, right aortic arch with aberrant left subclavian artery, right aortic arch with mirror image branching and ligamentum arteriosum arising from descending aorta.
Incomplete rings are: left pulmonary artery sling (left pulmonary artery arising from right pulmonary artery), innominate artery compression syndrome and left aortic arch with aberrant right subclavian artery [3].
What are the cyanotic heart lesions?
The classic cyanotic heart lesions all start with the letter “T.” Tetralogy of Fallot, truncus arteriosus, transposition of the great arteries, total anomalous pulmonary venous return and tricuspid valve atresia can all cause cyanosis.
When and why can total anomalous pulmonary venous return (TAPVR)
be a true congenital cardiac urgency?
TAPVR describes anomalous drainage of the pulmonary veins into the systemic venous atrium.
This can occur directly to the right atrium, via a remnant of the cardinal vein system (supra-cardiac), via a remnant of the umbilico-vitelline system (infra-cardiac) or as a mixture of these types.
Due to drainage of all blood to the right atrium, an atrial level shunt must be present.
If this shunt is restrictive to flow at the level of the accessory vein—profound respiratory distress and cardiogenic shock will result shortly after birth.
This is considered obstructive TAPVR and is an indication for emergent repair or extra-corporeal support if the diagnosis is not clear [1].
Why are ventricular septal defects (VSDs) approached with different treatment algorithms?
A VSD is a defect in the interventricular septum that results in blood flow from the left ventricle to the right ventricle and can result in too much blood flow to the lungs (heart failure).
Many VSDs, both muscular and peri-membranous, have potential to close on their own.
Therefore, if a VSD is small enough (restrictive to flow) that a patient can be medically managed (diuretics) and grow, surgery can be deferred.
Larger VSDs or those with associated defects often need to be closed in infancy.
Where is the heart’s conduction tissue and when is it in jeopardy?
The sino-atrial node is located on the atrial side of the junction of the right atrium and superior vena cava on the epicardial surface of the heart.
It should be considered with any right atrial or superior vena cava manipulation.
The AV node lies within the triangle of Koch—bounded by the coronary sinus, the tendon of Tedaro and the anteroseptal commissure of the tricuspid valve.
It is at risk with operations near the crux of the heart such as a VSD or atrioventricular septal defect (AVSD) closure.
What is a “tet spell?”
Tetralogy of Fallot (TOF) is a common cardiac diagnosis caused by anterior malalignment of the conal septum and resulting in 4 defects—VSD, overriding aorta, pulmonary stenosis and right ventricular hypertrophy (RVH).
As the RVH worsens, more blood is forced away from the lungs and into the aorta—espe- cially with a catecholamine surge – resulting in a cyanotic spell.
Anything that increases systemic vascular resistance (alpha agonists) and decreases the cat- echolamine response (soothing, narcotic, beta blocker) will help mitigate the cyanosis [1].
Which heart defect is most likely in a child born with trisomy 21 and how
likely?
Approximately 40% of patients with trisomy 21 have an AVSD. Conversely, approximately 75–80% of patients with AVSD have trisomy 21 [1].
What does “unbalanced” AVSD mean?
Some patients with an AVSD have a common atrioventricular valve that does not sit above 2 equally sized ventricles.
Some have severe enough ventricular hypoplasia that the heart cannot be divided into 2 systems and a single ventricle path- way is necessary.
When is a pulmonary artery band (PAB) needed and what are the pitfalls of placing one?
Pulmonary artery banding is a palliative procedure used to limit excessive pul- monary blood flow from a large left-to-right shunt and ameliorate heart failure.
In contemporary times, this is mostly limited to single ventricle patients with excessive pulmonary blood flow and occasional scenarios where complete repair of a 2 ventricle patient is deferred.
Achieving appropriate band tightness can be difficult as there are numerous and dynamic factors affecting pulmonary blood flow and pulmonary vascular resistance.
The band being placed too distally or migrating distally can cause right pulmonary artery impingement as well.
What is a Blalock Taussig (BT) Shunt and when is one needed?
The modern version of the BT shunt is anastomosing a polytetrafluoroethylene (PTFE) tube graft from the right subclavian artery to the right pulmonary artery.
This is performed to augment pulmonary blood flow and is frequently used as the initial palliation or part of the initial palliation in cyanotic single ventricle patients, but is also occasionally used to palliate 2 ventricle patients needing additional pulmonary blood flow if a complete repair is deferred.
What is the Norwood Procedure?
The Norwood procedure is the complex operation performed for hypoplastic left heart syndrome. It consists of: anastomosing the aorta to the pulmonary artery (Damus-Kaye-Stansel), enlarging the aortic arch, atrial septectomy and either a systemic to pulmonary artery (BT) shunt or right ventricle to pulmonary artery (Sano) shunt.
What are the 2nd and 3rd stages of the single ventricle pathway?
As an infant’s pulmonary vascular resistance falls after the first few months of life, their physiology gradually becomes better suited to tolerate the continuous single ventricle circuit of a Fontan.
The 2nd stage (in some cases actually referred to as hemi-Fontan) is a step toward the Fontan and is typically done between 3 and 6 months of age.
Most centers perform a bidirectional Glenn procedure, which is anastomosing the superior vena cava to the right pulmonary artery and removing the initial palliative shunt.
The Fontan completion is performed at about 2–5 years of age.
It consists of directing the inferior vena cava blood to the pulmonary artery via a tunnel or graft.
Upon completion, all the blood returning from the body is passively directed to the lungs.
What are some known long-term complications of Fontan circulation?
Among other things, plastic bronchitis and protein-losing enteropathy, occurring in up to 14% and 13% respectively, are both long-term complications of Fontan that carry a poor prognosis [1].
A 2-weeks-old male patient is brought to the emergency department with respiratory distress. He is not gaining weight.
His clinical examination shows stridor along with increased intercan-thal distance and short nasal bridge. His oxygen saturation is 97% in the room air. His chest x-ray suggests a narrowing of the airways. His echocardiography is performed, and it reveals two transverse aortic arches. What is the most common genetic syndrome associated with this condition?
Choices:
1. Noonan syndrome
2. Trisomy 13
3. Angelman syndrome
4. 22q11 deletion
Answer: 4-22g11 deletion
Explanations:
• This is a classical picture of the double aortic arch (DAA), as it presents in the earlier infancy.
• The clinical findings seen in DAA include an infant with stri-dor, dyspnea, failure to thrive, and choking episodes with feeding.
Examination in around 30% of the infants can show murmur or cyanosis.
• Chest x-ray is usually performed showing the narrow airways and dominant arch, which can be confirmed using MRI. Echocardiography can also support the diagnosis.
• Double aortic arch is usually associated with 22q11 deletion, sometimes it has been shown to be associated with trisomy 21 and 18.
Noonan syndrome is mostly associated with pulmonary valvular stenosis and atrial septal defects.
StatPearls
A 2-year-old girl is brought to the clinic with abnormal facies characterized by a prominent nose, notched nostrils, and small chin. She also has a history of a cardiac ventricular septal defect.
The oral cavity exam reveals an overt cleft palate. Which of the following is the most appropriate imaging study to be ordered before attempting a cleft palate repair in this patient?
Choices:
1. CT angiography
2. X-ray head
3. Bronchoscopy
4. Chest x-ray
Answer: 1-CT angiography
Explanations:
• The patient demonstrates velocardiofacial (VCF) or Shprintzen syn-drome, an autosomal dominant condition characterized by cleft palate, cardiac anomalies, distinct facial features, and learning dis-abilities. While patients with VCF syndrome benefit from cleft palate repair, it is essential to perform imaging studies to verify the location of the internal carotid artery, as it may be displaced and situated more medially. This is particularly important in patients who may require a posterior pharyngeal flap in order to prevent a major vessel injury.
•CT angiography would be the only imaging modality able to confirm the anatomical location of the internal carotid artery.
• An x-ray head and chest x-ray are imaging studies that would not demonstrate the location of the internal carotid artery.
• Bronchoscopy is a useful exam to assess the lower airways.
StatPearls
The most common primary cardiac tumour in children is:
A fibroma
B angiosarcoma
C rhabdomyoma
D teratoma
E myxoma.
C
Cardiac tumours are classified as primary (arising from the heart, more than 90% of which are benign) or secondary (representing metastases, which are uniformly malignant).
most cardiac tumours in children and adults represent metastatic disease. In children, these are secondary to non-Hodgkin’s lymphoma, leukaemia and neuroblastoma.
The most common primary cardiac tumour in children is rhabdomyoma, accounting for 50%–80% of all paediatric primary cardiac tumours.
other benign primary cardiac tumours vary according to age: in neonates and infants, fibroma and intrapericardial teratoma may occur, while in older children and adolescents, myxoma and fibroma are seen.
Rhabdomyomas are multiple, well-circumscribed, white, intracavitary or intramural masses that may occur anywhere in the heart.
most are diagnosed in the newborn period and may present with respiratory distress or heart failure, especially if large.
Tuberous sclerosis, an autosomal dominant mutation with variable expressivity, is a common association, with approximately 50% of patients with tuberous sclerosis having rhabdomyomas.
Approximately 30% of rhabdomyomas will regress spontaneously.
Rhabdomyosarcoma is the most common primary malignant cardiac tumour in children whereas angiosarcoma is the most common primary malignant cardiac tumour in adults; both portend a poor prognosis.
myxomas, arising from the interatrial septum, are the most common primary benign cardiac tumours in adults, usually diagnosed in the third to sixth decade of life.
Treatment is by surgical excision with reconstruction of the interatrial septum.
Fibromas represent the second most common primary benign cardiac tumour in children, and present usually as solitary large white non-encapsulated tumours in the left ventricular septum or free wall.
Presentations include left ventricular outflow tract obstruction and ventricular tachyarrhythmias.
Treatment is by surgical enucleation on cardiopulmonary bypass.
Intrapericardial teratomas are solitary, encapsulated tumours that are attached to the base of the heart. As with other teratomas, all three embryonic germ cell layers may be present. Treatment is by surgical excision.
SPSE 1
All of the following may be found in scimitar syndrome except:
A dextrocardia
B haemoptysis
C aortopulmonary collateral artery
D bronchopulmonary sequestration
E ventricular septal defect.
E
Scimitar syndrome is a form of partial anomalous pulmonary venous return where the right pulmonary veins drain into the inferior vena cava, with subsequent drainage into the right atrium.
The left pulmonary veins drain normally into the left atrium.
There is often an associated atrial septal defect (ASD) that is low in the interatrial septum, close to the orifice of the inferior vena cava.
The chest radiograph in the anteroposterior projection shows the scimitar sign, which is a crescent-like shadow in the right lower lung field, parallel to and distinct from the right heart border. This extra shadow is similar to a scimitar, which is a curved Turkish sword.
Right pulmonary artery hypoplasia may be present, as well as right lung hypoplasia. As a result, the heart may be shifted to the right; cases of mesocardia (midline heart) or dextrocardia (cardiac apex pointing to the right) have also been described.
Pulmonary parenchymal abnormalities include sequestration, with an anomalous systemic arterial blood supply, usually from the descending thoracic aorta to the sequestered lung.
A ventricular septal defect is not associated with this defect, whereas an ASD is often found.
If no ASD is present, those patients typically present later in life, often in adulthood, with right atrial enlargement and right ventricular volume overload.
An ASD results in an earlier presentation because of the increased right atrial and right ventricular volume overload from left-to-right shunting across the interatrial septum, in addition to the anomalous drainage of the right pulmonary veins into the right atrium. This results in exercise intolerance and palpitations from atrial tachyarrhythmias, although a number of patients may be asymptomatic.
Treatment is by rerouting the anomalous right pulmonary veins into the left atrium, either through a baffle across the ASD, or by direct anastomosis of the pulmonary veins to the left atrium.
SPSE 1
