Lecture 25 - 27: Congenital Heart Defects Flashcards
Describe the right atrium
Broad triangular appendage, trabeculated
Describe the left atrium
Finger-like appendage, smooth surface
T/F: The left atrium receives the pulmonary veins
FALSE! This is an independent variable
Where do we find the septum primum connections?
L atrial septal surface
How do we define the tricuspid and mitral valves?
By which ventricle they serve (mitral = LV, tricuspid = RV) NOT by which atrium they guard
Describe the right ventricle
Irregular shape, heavy trabeculations, tricuspid attached to septum
Describe the left ventrile
Bullet-shaped, smooth septal surface, absent of mitral attachments to septum
What is the pulmonary artery? What is the aorta?
Gives rise to pulmonary artery branches; gives rise to at least one of the coronary arteries
What is the normal atrial situs?
Situs solitus
What happens in sinus inversus?
RA is left-sided and the LA is right-sided
In sinus inversus, where are the septum primum attachments?
Right-sided (w/ the LA)
Describe situs ambiguous
Chaotic lateralization in which some portions are organized in solitus and others in inversus
What is the normal ventricular situs?
D-looped
What is the abnormal ventricular situs? What is an important note?
L-looped; normal only for situs inversus
In situs solitus, what is the orientation of the valves of the great arteries?
Aortic valve is right and posterior to the pulmonic valve
What is the most common cause of neonatal cyanosis?
Transposition of the great arteries
In transposition of the great arteries, circulation is in…
Parallel
What two communications allow a baby to survive if born with transposition of the great arteries?
Ductus arteriosus (give PGE) and foramen ovale
What is the corrective procedure of choice for transposition of the great arteries?
Arterial switch
What is transposition of the great arteries associated with?
Maternal diabetes
What are the four characteristics of the great arterials in situs solitus?
- Aorta w/ fibrous continuity to mitral valve; 2. Pulmonary valve seperated from tricuspid via subpulmonary muscle; 3. Aortic valve is to the right and posterior of the pulmonic valve; 4. LV aligned with aorta and RV aligned with PA
What is another example of malpositions of the great arteries (besides transposition)
Double outlet from L or R ventricle
What happens to the foramen ovale when a baby is born?
High left ventricular pressure forces it shut, remains patent in 1/5 of individuals
When is the pulmonary resistance equivalent to adult levels?
At 8 weeks
What is the pathophysiology of large ventricular septal defects?
Because pulmonary resistance is lower than systemic resistance, and the pressures inside the single ventricle is the same, the pulmonary track will get larger flow –> inefficient pulmonic circulation
How/when will a baby present with a large VSD? (5)
Several weeks after birth with dyspnea, tachypnea, failure to thrive, poor feeding, early HF symptoms
What is the most common congenital heart abnormality?
VSD
What is VSD associated with?
Fetal alcohol syndrome
What is a possible course of a small VSD (%)? What is another name of this condition? Describe.
Closure on its own (50%); restrictive VSD in which the resistance of the hole itself impedes flow through it (resistance in series)
What is a possible course of a large VSD? What is this called?
Pulmonary hypertension –> R to L shunt; Eisenmenger syndrome
What are three symptoms of Eisenmenger syndrome?
RV hypertrophy, polycythemia (due to hypoxia), clubbing
What is a nonrestrictive VSD?
A large VSD that does not restrict transmission of pressure (aka, pressure in ventricles is equal)
What % of atrial septum defects are not diagnosed until adulthood?
25%
Ostium primum defect is associated with what?
Down’s syndrome
Physical sign of an ASD? Why?
Split S2: delayed closure of pulmonic valve due to increased volume
One frightening complication of an ASD
Paradoxical embolism
Why is there L –> R shunting in an ASD?
Because the L ventricle is less compliant (NOT because of systemic vs pulmonic circulation, from which the atria are guarded)
What can ASD lead to in adulthood? (3)
Hypertension, ischemic heart disease, and a less compliant left heart
Describe Eisenmenger syndrome
Elevated pulmonary vascular resistance causes reversal of the original shunt (to the right-to-left direction) and systemic cyanosis
What is the most common cause of cyanosis after infancy?
Tetralogy of Fallot
What are the 4 features of Tetralogy of Fallot
VAD, subvalvular pulmonic stenosis, overriding aorta that receives blood from both ventricles, RV hypertrophy
What is the primary cause of the shunt flow across the VSD in Tetralogy of Fallot?
Severity of the pulmonic stenosis
When does Tetralogy of Fallot manifest most strongly? Why? What do children do to compensate?
During exercise or anything that causes systemic vasodilation (feeding, crying); children will to squat to increase arterial resistance, which decreases the R –> L shunt
What is tx for Tetralogy of Fallot?
Surgical correction to close VAD and enlarge subpulmonary infundibulum
What are four other (pathoma) congenital heart abnormalities that cause cyanosis?
- Truncus arteriosis, due to mixing; 2. Tricuspid atresia, due to hypoplastic RV; 3. Coarctation of the aorta, if infantile it’s associated with PDA and Turner Syndrome; 4. PDA, associated with congential rubella
PDA and infantile coarctation of the aorta are associated with what physical finding? Why?
Cyanosis of the lower extremities because the PDA is after the branches of the aortic arch
