Congenital Heart Defects Flashcards
Three shunts in fetal circulation?
ductus venosus, foramen ovale, & ductus arteriosus
What happens to the fetal shunts?
as soon as baby is born, fetal shunts & umbilical vessels are no longer needed & become occluded
What happens w/ severe fetal cardiac malformations ?
They are incompatible w/ intrauterine life resulting in either embryonic death or fetal abortion
What happens w/ cardiac malformations that are compatible w/ intrauterine life?
result in post natal heart failure or sudden death
What happens w/ minor cardiac malformations?
they are well compensated by physiologic adaptive mechs & cause no clinical signs. in these cases, defects are purely incidental finding @ slaughter or post-mortem
The etiological diagnosis of congenital heart defects is rarely reached. What are some etiologies?
- genetic: single or multiple gene effects, chromosomal abnormalities
- maternal infections: parvo, bluetongue virus, BVD, rubella
- nutritional deficiencies: vit A, pantothenic acid, riboflavin, zinc
- drugs: thalidomide, ethanol, salicylates
- other teratogens: radiation, fetal hypoxia, maternal diabetes
- multifactorial (genetic & enviro factors)
What are most common congenital heart defects (categories)?
- defects that cause vol overload
- defects that cause press overload
- defects that cause early cyanosis
- miscellaneous
What are the most common congenital heart defects that cause volume overload?
Left to right shunts
1. Patent Ductus Arteriosus (PDA)
2. Atrial Septal Defect (ASD)
3. Ventricular Septal Defect (VSD)
valvular regurgitation
1. Valvular dysplasias
What is a left to right shunt?
When a defect is present btwn the right and left cardiac chambers, blood flows down the pressure gradient from L to R side
What is valvular regurgitation?
regurgitated blood from the ventricles to the atria leads to progressive atrial dilation & eccentric ventricular hypertrophy of the affected side
What are the most common congenital heart defects that cause press overload?
Aortic & pulmonic stenosis
Pathogenesis of pressure overload?
ventricular outflow obstruction causes a progressive/chronic increase in intraventricular pressure resulting in concentric hypertrophy of the affected side
What are the most common congenital heart defects that cause early cyanosis?
Right to L shunts
1. Tetralogy of Fallot
2. Transposition of Great Arteries
What are the most common miscellaneous congenital heart defects?
- persistent right aortic arch
- ectopia cordis
What is a right to left shunt?
- in these diseases, nonoxygenated blood from the right heart compartments flow into the left heart compartments or directly into the systemic circulation
- this also occurs in cases of PDA & VSD when there is reversal of shunting from R to L
What is the ductus arteriosis?
Normal communication btwn pulmonary artery & aorta in fetal circulation. normally closes after birth forming LIGAMENTUM ARTERIOSUM.
Species where patent ductus arteriosus is seen?
all spp but particularly in dogs (> poodles, collies, pomeranians)
diagnosis of patent ductus arteriosus can only be made when?
if ductus fails to close 3 wks after birth
Hemodynamics of patent ductus arteriosus ?
L to R shunt btwn aorta & pulmonary artery -> increased pulmonary blood flow (hyperflux) -> pulmonary hypertension -> press overload in RV & vol overload in LV
MD?
patent ductus arteriosus
MD?
patent ductus arteriosus
MD?
patent ductus arteriosus
How long may closure of ductus arteriosus take in foals?
several days
Is there a difference between structural and functional closure of the ductus arteriosus?
yes
steps of L to R shunts?
high pulmonary vascular resistance -> medial hypertrophy or irreversible obstructive intimal lesions “plexogenic arteriopathy” -> shunt reverses (R to L) -> late cyanosis (Eisenmenger syndrome)
What is atrial septal defect and what are two main forms?
communication btwn L & R atrium in postnatal life
1. persistence of fetal FORAMEN OVALE (probe-patent foramen ovale)
2. true atrial defect in which there is failed closure of atrial septum
Clinical significance of minor atrial defects?
little clinical significance; no clinical signs
In which species is atrial septal defect most common?
dogs & cats
MD?
patent foramen ovale
MD?
patent foramen ovale
MD?
atrial septal defect
MD?
atrial septal defect
Probe- patent foramen ovale?
in 20% of people, probe can be passed through patent foramen ovale but this opening is not fxnal (no shunt)