Congenital Heart Defects Flashcards
1
Q
describe fetal blood flow
A
- RV delivers most of output to placenta for O2 uptake and LV pumps blood to heart, brain and upper body of fetus. Before birth, oxygenation of blood occurs through the placenta and after birth, it occurs through the lungs
- fetus in maintained in a low O2 state (PO2 30-35 mmHg, hemoglobin sat of 60-70%)
- ductus venosus allows majority of blood from umbilical vein to bypass hepatic circulation and pass directly into IVC - to RA where 40% of blood moves through foramen ovale into LA, then passes into LV and ejected into aorta and perfused to head and upper extremities. Venous blood from these areas return back to RA through SVC and into RV and pulm arteries and beccause of high pulm vascular resistance almost 90% of blood ejected into pulm artery gets diverted through ductus arteriosus into descending aorta, blood perfuses lower extremities and is returned to placenta via umbilical arteries
2
Q
epidemiology of congenital birth defects?
A
- 8/1000 live births
- one of leading cause of death in infants
- genetic: microdeletion in long arm of xsome 22, also seen in downs and Turners syndrome
- enviro: maternal diabetes, ETOH, and teratogens
- gender: ASD, VSD, PDA, and pulmonic stenosis more common in girls. Left sided lesions more common in boys
3
Q
Classification of congenital defects?
A
- Acyanotic CHD: pink babies: left to right shunts - cyanotic CHD: blue babies: right to left shunts - obstructive CHD: narrowing structures
4
Q
Types of acyonatic CHD?
A
- left to right cardiac shunts, condition where blood from systemic arterial circulation mixes with systemic venous blood
- ASD
- VSD
- PDA: patent ductus arteriosus
5
Q
Types of cyanotic CHD?
A
- R to L shunt, shunt allows blood to flow from R to L side of heart
- tetralogy of fallot
- transposition of Great arteries
6
Q
Types of obstructive CHD?
A
- obstruction to R side of heart: pulmonic valve stenosis (PVS) - to L side: coarction of aorta congenital aortic stenosis (AS)
7
Q
Shunting of blood in fetus?
A
- shunting of blood occurs b/t R and L atria, through the foramen ovale, and b/t the pulmonary artery and aorta through the ductus arterioles
- the placenta supplies O2 to fetus through umbilical vein to heart, enters IVC then goes in RA
- from RA pushed through foramen ovale into LA
- Blood in LA is from pulm veins and blood from RA – blood enters LV and then LV pumps pumps blood through aortic valve into aort, majority of output goes to head. Rest of output from LV and RV via ductus arteriosus supplies lower body and fetus, after lower body perfused, deoxygenated blood returned to fetus via umbilical arteries
8
Q
What 2 events occur at birth that change fetus circulation?
A
- umbilical cord is clamped and breathing begins
- this reaction causes sudden increase to resistance of systemic circulation, lungs begin to oxygenate the blood increasing PO2, causing a decrease in pulmonary arterioles constriction and decreasing pulm vascular resistance
- pulm resistance falls below systmic circulation which changes the blood flow across the ductus arteriosus to left to right shunt, this results in closure of foramen ovale and ductus arteriosus
9
Q
What are the 3 main types of atrial septal defects?
A
- opening in atrial septum permitting blood b/t 2 atrias
- 3 major types:
ostium secundum (Most common) - seen in about 10% of CHD
sinus venosus (least common)
ostium primum
10
Q
Clinical presentation of ASD?
A
- most often have no CV sxs
- rarely present with CHF
- heart is usually hyperactive with RV heave felt best at lower L sternal border
- S2 is widely split and fixed at pulmonary area
- crescendo-decrescendo systolic ejection murmur
11
Q
Dx of ASD?
A
- initial testing is usually CXR and EKG
- echo is test of choice!!
12
Q
Tx of ASD?
A
- surgical
- percutaneous transcatheter closure: usually done b/t ages 1-3
this may be done earlier in children with CHF
13
Q
What is VSD?
A
- abnormal opening in ventricular septum which allows blood to flow across right and left ventricles. Single most common reason for infants to see cardiologist!
14
Q
4 types of VSD?
A
- membranous defect (most common)
- subpulmonic or outlet defect
- AV or inlet defect
- muscular defect
15
Q
Clinical presentation of VSD? (small - mod)
A
- small to mod shunts usually have no CV sxs
- small shunts have loud, harsh holosystolic murmur
16
Q
Clinical presentation of VSD large shunts?
A
- frequent respiratory infections
- poor wt gain
- dyspnea and fatigue are common
- CHF develops b/t 1-6 months
- pansystolic murmur
17
Q
Dx of VSD?
A
- initial CXR and EKG
- echo confirms dx, location of lesion and size of shunt