5. Congenital Heart Disease Flashcards
Congenital heart disease (CHD)
Cardiac or large vessel abnormalities present at birth
Most CHDs result from defective embryogenesis during gestational weeks 3-8
CHDs most common cardiac disease among children
Severe abnormalities - incompatible with intrauterine survival
Defects involving specific chambers or regions allow for live birth
Critical CHD
Requiring surgery or catheter - based intervention in first year of life
Shunt
Abnormal communication between chambers or blood vessels
Malformations caused left to right shunts
Atrial septal defects (ASD)- hole in heart, abnormal opening in dividing wall of Atria (upper chambers)
Ventricular septal defect (VSD) - hole in heart, abnormal opening in dividing wall of ventricles (lower chambers)
Patent ductus ateriosus (PDA) - opening between 2 major blood vessels leading from heart, normal before birth and closes shortly after birth
Malformations causing right to left shunts
Tetralogy of fallot
Patent foramen ovale (PFO)
Malformations causing an obstruction
Coactation of the aorta
Categories of Congenital HD
Based on:
Existence /absence of cyanosis
Increase or decrease in blood flow of pulmonary circulation
Obstruction of blood flow from ventricles
Acyanotic category
Increase pulmonary blood flow = atrial septal defect, VSD, PDA, atrioventricular canal
Obstruction of blood flow from ventricles = coactation of aorta, aortic stenosis, pulmonary stenosis
Cyantoic category
Decrease pulmonary blood flow - tetralogy of fallot, tricuspid altresia
Mixed blood flow - transposition of great arteries, total anormatous pulmonary venous return, turn us ateriosis, hypoplastic L heart syndrome
Etiology of Congenital HD
Sporadic genetic abnormalities are major known causes
Most common genetic cause = trisomy 21
Environmental and maternal factors
Nutritional factors: folate supplementation decrease risk of CHD
Left to right shunts
Cause pulmonary volume overload
Chronically increase both volume and pressure in pulmonary circulation
ASD
VSD
PDA
Right to left shunts
Bypass lungs leading to hypoxia/cyanosis
Allow venous emboli to enter systemic circulation
Finger and toe chubbing
Pathophysiology of Left to Right shunts
Abnormal connection between systemic and pulmonary circulations
The overall clinical effect is recirculation of already oxygenated pulmonary venous blood through pulmonary venous vasculature
Nuerohumoral activation: SNS, renin-angiotensin system
Pulmonary HT: continuous increase of pulmonary artery pressure sometimes becomes systemic
Atrial septal defect (ASD)
Left to right
Abnormal fixed openings in atrial septum that allows communication between L and R atria
Most common congenital cardiac abnormality in adults
ASD usually asymptomatic until adulthood
Pathophysiology of ASD
Pulmonary vascular resistance is much less than systemic vascular resistance = L to R shunt
Pulmonary and systemic resistances
Compliance of R and L ventricles
Size of defect
ASD clinical features
Mummer is often heard as a result of the flow through the pulmonary valve and/or through ASD
ASD closure reverses the blood flow abnormality and prevents complications
Ventricular Septal Defect (VSD)
Left to right
Incomplete closure of the ventricular septum causes blood to communicate between L and R ventricles
Most common form of congenital abnormality
VSD clinical features
Most VSDs that clinically manifest in children are associated with other congenital cardiac abnormalities such as tetralogy of fallot
Large defects generally cause significant L to R shunting causes early R ventricular hypertrophy and pulmonary HT
Patent ductus ateriosus (PDA)
Left to right
Allows blood to flow between aorta and pulmonary artery during fetal development thus bypassing the lungs
Ducts normally close within 1-3 days of life - persistent PDA leads to L to R shunting
Clinical implication of PDA
In premature infants is essentially all L to R from aorta into pulmonary arteries
Therefore there is an excessive flow through pulmonary circulation and systemic hypo-perfusion
Tetralogy of Fallot (toF)
Right to left
One of the most common congenital heart lesions that needs attention in first year of life
Major pathologic features: Stenosis of pulmonary artery intraventricular communication (VSD) Deviation of origin of aorta to right coverriding aorta Concentric R ventricular hypertrophy
Clinical features ToF
If left untreated patients can survive into adult life
Symptom severity related to extent of pulmonary stenosis
Patent foramen ovale
Foramen ovale= small hole resulting from defective post nasal closure of flap
It closes prematurely in approx 80% of people by 2 years old
Unsealed flap can open if R sided pressures become elevated and cause paradoxical embolism
Coarctation of the aorta
Obstructive congenital abnormality
Constriction of aorta
Pathogenesis:
Congenital: genetic predisposition in families, may be associated with Turners Syndrome
Acquired: due to inflammatory disease of the aorta
