Module 6 CVS continued- Congenital Heart Flashcards
What are congenital heart diseases?
Abnormalities of the heart or great vessels that are present from birth
What are the two physiologic shunts?
- Foramen Ovale
2. Ductus Arteriosus
What is the normal fetal to adult circulation transition?
At birth baby breathes — lungs inflate and pulmonary resistance (right sided pressures) fall
- –blood flow stops through foramen ovale (flap valve)
- –ductus arteriosus closes by 15 hr of life
- –prostaglandins (PGs) (main patency, produced in placenta, metabolized in lungs, at birth decreased production and increased breakdown)
What are some causes of congenital heart defects?
Main known causes: sporadic genetic abnormalities
—trisomy 13,18,21 and monosome X
What are the right to left shunts (cyanotic), called the terrible T’s
- Tetralogy of Fallot
- Truncus arteriosus
- Tricupsid atresia
- Total anomalous pulmonary venous connection
- Transposition of great vessels
What are the left to right shunts (non cyanotic), called the D’s
- Atrial Septal Defect( ASD)
- Ventricular Septal Defect (VSD)
- Patent Ductus Arteriosus (PDA)
What is the reason for cyanosis in right to left shunts?
Deoxygenated blood mixes with oxygenated blood — flows into the systemic circulation
–if caused by congenital heart defect, requires R- sided circulation to flow to L-sided
circulation bypassing the lungs
Tetralogy of Fallot is the most common form of cyanotic congenital disease (NOTCH2 mutation), what are the 4 defining features in order
- Right ventricular hypertrophy
- VSD
- Overriding aorta
- Pulmonary stenosis (most important for patients)
What is the pathogenesis for tetralogy of fallot?
Antero-superior displacement of the infundibular septum
What is the presentation for an infant with tetralogy of fallot?
Becomes apparent at 6 months after birth -- decreased fetal Hb decreases (holds onto more oxygen due to high affinity) --- finger clubbing Tet spells (squatting) -- increased after load to reverse the shunt -- left to right --- cyanosis transiently improves (increases peripheral or systemic vascular resistance and this is what makes the shunt switch)
What are the complications of tetralogy of fallot?
DVT: paradoxial embolism – bypasses pulm circulation and goes to the systemic circulation (aka legs or brain)
Jet lesions: right to left ventricle– lands on left endocardial surface and damages it
Chronic hypoxia: (Because bypassing the lungs) so in response to low oxygen levels kidney makes Erythropoietin (EPO) and this leads to secondary polycythemia (increased RBCs)
What investigations are done for tetralogy of fallot?
Cardiac Cath
Echo
Boot shaped heart on CXR
The next T is truncus Arteriosus, what is involved in this shunt?
Failure of partitioning of embryologic truncus into aorta and pulmonary artery
- -Single great artery gets blood from both ventricles
- -underlying VSD
- -blood from both ventricles mixes
- –cyanosis
The third T is tricuspid atresia, what is involved in this shunt?
Complete occlusion of the tricupsid valve oriffice
- -underdeveloped RV
- -mitral valve is larger than normal
- -R to left shunt though ASD (bypass obstruction)
- –L to right shunt through VSD (get blood from RV)
- -cyanotic from birth
- –high mortality
The fourth T is Total Anomalous Pulmonary Venous Connection (TAPVC)
Pulmonary veins fail to join the left atrium
- -pulmonary return vessels drain into the left innominate vein or coronary sinus
- -ASD always present
- –R to left shunting through ASD due to lower left atrial pressure
- -left to right through ASD (No normal return) results in cyanosis
The fifth and final T is transposition of the great arteries, what does this involve?
Aorta off RV and pulmonary artery off LV
- –AV connections normal (2 isolated systems)
- -LV to the lung and LA from the lung
- –RV to the body and RA to the body
- -incompatible with life unless a shunt is present
VSD is the first L to R shunt what is affected in this shunt?
Membranous VSD – most common congenital heart disease (Asymptomatic)
- –associated with trisomy 21,13,18
- –incidental finding on examination or ECG