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Pathology of congenital defects
Terms in this set (39)
When to congenital heart defects develop?
Abnormalities of the heart or great vessels present since birth. Most arise from faulty embryogenesis during gestational weeks 3-8.
Congenital heart disease basics
Most severe anomalies are incompatible with intrauterine survival. Many are morphogenetic defects of individual chambers or regions of the heart with the rest of the heart developing normally. As the muscular component develops normally the vessels may not have the appropriate connections with specific cardiac chambers. Some forms of congenital heart disease are obvious after birth. Others may not become evident until adulthood. Even after surgical correction the heart may not be fully normal. Cardiac remodeling and hypertrophy may be irreversible and needed for survival. Some of these changes can cause late onset arrhythmias , ischemia and myocardial dysfunction.
Most common heart disease amongst children
Most common heart disease among children. 1% of live births, higher in premature infants and stillbirths. In past few decades incidence has risen due to increased diagnostic sensitivity.
What is the most common genetic cause of congenital heart disease?
Down syndrome most common known genetic cause of congenital heart disease
Main known cause of congenital heart disease
The main known causes of congenital heart disease are sporadic genetic abnormalities. This can lead to single gene mutations, small chromosomal deletions or deletions of whole chromosomes. Mutations in genes encoding for transcription factors NKX2-5, GATA-4, TBX20 are associated with atrial septal defects and ventricular septal defects.
Associated with the lesion of chromosomes 22q 11.2, the fourth branchial arch end the derivatives of the third and fourth pharyngeal pouches develop abnormally leading to abnormal formation of the thymus parathyroids and heart. A region on chromosome 22 has a major role in the development of the conotruncus, the branching arches, and the face. Associated with anomalies of the fourth branchial arch and third and fourth pharyngeal pouches. Hypoplasia of the thymus and parathyroids causes immune deficiency and hypocalcemia.
Pharyngeal problems and thymus problems may result because they have a common path of development (genesis)
Environmental factors leading to congential heart disease
1. Environmental factors include exposure to teratogens
2. Congenital rubella infection
3. Gestational diabetes: Be cognizant of this. Strict blood sugar control in pregnancy is important
4. Nutritional factors: Intake of folate may reduce the risk of congenital heart defects
abnormal communication between chambers or blood vessels. Allows blood to pass from right to left or vice versa depending on pressure relationships
Right to left shunt usually present as what?
Defects with Right to left shunting usually present as cyanosis shortly after birth. Cyanosis occurs due to decreased pulmonary blood flow and poorly oxygenated blood enters systemic circulation.
Defects with Left to Right shunting may be relatively asymptomatic at birth, but the shunt can eventually reverse.
1. Increased flow through the pulmonary circulation results in hypertrophy of pulmonary vessels and pulmonary hypertension.
2. Increased Pulmonary resistance eventually results in reversal of shunt, leading to late cyanosis (Eisenmenger Syndrome) with right ventricular hypertrophy, polycythemia, and clubbing.
Left to Right Shunts
ASD (Atrial Septal Defect
VSD (Ventricular Septal Defect)
PDA (Patent Ductus Arteriosus)
Complete atrioventricular canal defect
Large VSD with irreversible pulmonary hypertension
Atrial Septal Defect
Abnormal opening in the atrial septum with communication of blood between the left and right atria. Usually asymptomatic until adulthood due to low pressure difference between the atria- As opposed to mixing in ventricles where you are more likely to have comingling of oxy and deoxy blood. Irreversible pulmonary HTN develops in less than 10% of pts with uncorrected ASD.
accounts for 90% of ASDs is located at a deficient or fenestrated oval fossa atrial aperture may be single multiple or fenestrated.
Defect in the septum that divides right and left atria; most common type is ostium secundum (90% of cases). Ostium primum type is associated with Down Syndrome. Results in the left to right shunt and split S2 on auscultation (increased blood in right heart delays closure of pulmonary valve).
adjacent to AV and is usually associated with a cleft anterior mitral leaflet
near entrance of Superior Vena Cava, usually associated with anomalous connections to right pulmonary veins to the SVC or right atrium
cor pulmonale (coronary hypertension), cardiac cirrhosis, and paradoxical embolization (something from left side emobolizing to right side)
Ventricular Septal Defect
Incomplete closure of the ventricular septum with free communication and a left to right shunt, associated with fetal alcohol syndrome.
1. Classified according to
size and location
2. Most are the size of the aortic valve orifice
90% involve the membranous septum
4. The rest lie below the PV (infundibular VSD) or in the muscular septum
4. Most are
some may be multiple
50% of small muscular VSDs close spontaneously. Pt may not be diagnosed with it and have no symptoms.
However, Large defects may result in right ventricular hypertrophy which may eventually cause a
right to left shunt
which can result in irreversible pulmonary disease, if not treated can result in cyanosis and death
Right to Left Shunts (4Ts, 2P's)
1. Tetralogy of Fallot
2. Transposition of the great arteries
3. Tricuspid atresia
4. Total anomalous pulmonary venous connection
1. Persistent truncus arteriosus
2. Paradoxical emboli: emboli arising in peripheral veins can bypass lungs and enter systemic circulation with brain infarcts and abscesses being possible complications
Patent Ductus Arteriosus
Failure of the ductus arteriosus to close at birth, associated with congenital rubella. Results in left to right shunt between the aorta and the pulmonary artery. During development, the
normally shunts blood from the pulmonary artery of the aorta, bypassing the lungs. Asymptomatic at birth with continuous
"machine like" murmur
. Shunt at first is left to right with no cyanosis. Obstructive pulmonary vascular disease ensues with reversal of flow and its consequences. This is example of reversal of shunt.
Atrioventricular Septal Defect
Results from abnormal development of embryologic A-V canal where the superior and inferior endocardial cushions fail to fuse causing incomplete closure of the A-V septum and inadequate formation of the Tricuspid Valves and Mitral Valves.
primum ASD and a cleft anterior mitral valve leaflet causing mitral insufficiency
large combined A-V septal defect
large common AV valve
, all four chambers freely communicate causing hypertrophy of each often
associated with Down syndrome (know this!)
Tetralogy of Fallot (2 different issues that give rise to 4)
1. pulmonary stenosis
2. right ventricular hypertrophy
3. overriding aorta
4. ventricular septal defect
Right to left shunt leads to early cyanosis, degree of stenosis determines the extent of shunting and cyanosis. Patients learn to squat in response to a cyanotic spell, increased arterial resistance decreases shunting and allows more blood to reach the lungs.
*"Boot Shaped" heart on XRay".
What determines direction of flow of Tetralogy of Fallot?
Clinical consequences depend on the severity of the subpulmonary stenosis. May present differently.
Severity of obstruction to right ventricular outflow determines the direction of blood flow
. May start out as left to right shunt, but can switch to right to left. If stenosis is mild the shunt may be left to right without cyanosis. If stenosis increases there is greater resistance to right ventricular outflow and can cause a right to left shunt with cyanosis. With greater subpulmonary stenosis the pulmonary arteries get smaller and thinner while the aorta increases in diameter and becomes engorged.
Morphology of TF
Heart often large and "boot-shaped" especially if VSD is large
2. Aortic valve forms superior border of VSD and overriding the defect and both ventricular chambers
3. Obstruction of right ventricular outflow is due to subpulmonic stenosis and can be accompanied by PV stenosis
4. Aortic valve insufficiency or ASD may be present
5. A right aortic arch is present in 25% of cases
Transposition of Great Arteries
A characterized by pulmonary artery arising from the left ventricle and aorta arising from the right ventricle. Associated with Maternal Diabetes. Presents with early cyanosis; pulmonary and systemic circuits do not mix.
1. Creation of shunt (allowing blood to mix) after birth is required for survival
2. PGE can be administered to maintain a patent ductus arteriosus until definitive surgical repair is performed.
Results in hypertrophy of the right ventricle and atrophy of the left ventricle.
TGA and VSD have a stable shunt
TGA and patent foramen ovale are unstable shunts which close, requiring intervention to create a shunt.
RV hypertrophies because it functions as a systemic ventricle
LV atrophies because of the low resistance pulmonary circulation
Outlook for pts depends on the degree of mixing of the blood, the magnitude of hypoxia and the ability of the right ventricle to maintain systemic circulation
Without surgery most pts die in the first few months of life
Characterized by a single large vessel arising from both ventricles. Truncus fails to divide. Presents with early cyanosis; deoxygenated blood from right ventricle mixes with oxygenated blood from left ventricle before pulmonary and aortic circulations separate.
Results from developmental failure of separation of the embryologic truncus arteriosus into the aorta and pulmonary artery. Result is a single great artery receiving blood form both ventricles with an underlying VSD, and gives rise to the systemic pulmonary and coronary circulations. Early cyanosis due to mixing of blood from RV and LV and an increased pulmonary blood flow. Danger of irreversible pulmonary hypertension.
Occlusion of the Tricuspid Valve opening. Results embryologically from unequal division of the Atrioventricular canal, Mitral valve is larger than normal.
Hypoplasia of Right Ventricle. Circulation maintained by a right to left shunt through an Atrial Septal Defect or patent foramen ovale. Ventricle Septum Defect present allows for communication between the LV and the great artery that arises from the hypoplastic right ventricle.
Cyanosis present and prominent at birth with high mortality in the first weeks of live
: Easily diagnosed with EKG and need to be corrected
Total Anomalous Pulmonary Venous Connection (TAPVC)
No pulmonary veins join the left atrium. The common pulmonary vein fails to develop or becomes atretic. Primitive systemic venous channels from the lung remain patent. TAPVC drains into the left innominate vein or to the coronary sinus. Either a patent foramen ovale or an ASD is present so venous blood can enter the atrium.
1. Hypertrophy of the right atrium and right ventricle with dilation
2. Left atrium is hypoplastic
3. Left ventricle of normal size
4. Cyanosis may be present
Coarctation of the Aorta
Narrowing of the aorta, classically divided into infantile and adult forms.
Infantile Coarctation of the Aorta
associated with a Patent Ductus Arteriosus, coarctation lies after (distal to) the aortic arch but before (proximal to) the patent ductus arteriosus. Presents as lower extremitiy cyanosis in infants, often at birth. Associated with Turner Syndrome.
Frequent structural anomaly
Males 2x more then females
(45, X), short stature, low-set ears, Shield chest, café au lait spots, left neck, lymphedema, short fourth metacarpals, primary amenorrhea due to accelerated loss of oocytes,
* due to collateral circulation through intercostal arteries- KNOW THIS ASSOCIATION.
Adult form of Coaractation of the Aorta
is not associated with patent ductus arteriosus, coarctation lies after (distal to) the aortic arch. Presents as hypertension in the upper extremities and hypotension with weak pulses in the lower extremities, classically discovered in adulthood. Collateral circulation develops acorss the intercostal arteries, engorged arteries cause "notching" of ribs on XRay. Associated with bicuspid aortic valve.
Coarctation of the Aorta with PDA
Manifests itself early in life
Infants may not survive the neonatal period without surgical intervention
Need to identify this because you may have mixing of blood
Coarctation of the Aorta without PDA
Most children are asymptomatic and may go unrecognized until adulthood
Hypertension in upper extremities with weak pulses and lower BP in lower extremities may result
Notching of ribs due to collateral circulation involving the intercostal and internal mammary arteries may result
Murmurs often present during systole
Pulmonary Stenosis and Atresia
1. Obstruction of pulmonary valve which can be mild or severe. This is lack of formation of valve
2. May be an isolated defect or associated with other anomalies
3. Right Ventricular Hypertrophy may develop
4. If valve is entirely atretic it is often associated with a hypoplastic right ventricle and an ASD, blood then enters the lungs through a Patent Ductus Arteriosus
5. Mild stenosis may be asymptomatic
Aortic Stenosis and Atresia
Narrowing and obstructions of the aortic valve present at birth
Three types of stenosis: valvular, subvalvular and supravalvular
Valvular aortic stenosis
cusps are small, thickened or abnormal in number in severe cases may have hypoplasia of LV and ascending aorta, the ductus must be open to allow blood flow to the aorta and coronary arteries, almost always fatal in the first week of life.
Aortic Stenosis - Subaortic Type
Represents as a thickened ring or a collar of dense endocardial fibrous tissue below the level of the cusps
Aortic Stenosis - Supravalvular Type
Inherited form of aortic dysplasia where ascending aortic wall is thickened causing luminal constriction
Williams syndrome: supravalvular type associated with developmental disorders of other organ systems and vascular system and hypercalcemia of infancy. Know this association!
Mutations of elastin gene can cause supravalvular stenosis
Congenital stenosis can be well tolerated unless very severe but threat of sudden death is present
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