The Developing Heart Flashcards
Congenital heart defects are the most _________ ________ malformations in newborns, they are present in about ___ % of live births.
Congenital heart defects are the most frequent congenital malformations in newborns, they are present in about ~1% of live births.
Has survival of children with congenital heart disease improved? Why?
Survival of children with congenital heart disease has greatly improved thanks to medical advances in Canada and around the world.
60 years ago <20% of infants born with complex heart defects reached adulthoo
Now more than 90% do (even those with complex congenital heart defects)
How are congenital heart defects usually treated?
surgically
Do we expect the incidence rate of congenital heart defects to increase or decrease, why?
– Many with surgical intervention are now having children, so we expect incidence rate to rise
(Defects usually shorten life span, even after surgical correction, but it’s improving)
What percentage of congenital heart disease (CHD) is multi-factorial? What does multifactorial mean? (genetic and environmental contributors)
80% of congenital heart disease (CHD) is multi-factorial (genetic and environmental contributors)
Often there’s no known cause, or it may be caused by
• Viral infections such as measles (rubella)
– MMR vaccine has reduced incidence
• Drug or alcohol abuse during pregnancy.
What are the types of mutations in CHD?
Unknown (61.7%) De novo CNV (15%) Chromosomal syndrome (12%) De novo gene mutation (10%) Inherited gene mutation (1.3%)
20% of CHD results from ____________
chromosomal anomalies, Mendelian syndromes, non-syndromic single gene disorders
CHD is a component of many syndromes (single and multiple gene disorders). What are some examples?
Alagille, Holt-Oram, Noonan, Adams-Oliver, Down’s, DiGeorge, Char,
Williams-Beuren, etc.
Non-syndromic CHD
single gene disorders / monogenic
What usually causes monogenic forms in non-syndromic CHD?
Usually of monogenic forms are caused by single high penetrance autosomal
dominant mutation. Often missense.
How many genes have been linked to non-syndromic CHD?
more than 40
Examples of heart defects
TGA – Transposition of the great arteries
HLHS – hypoplastic left (right) heart syndrome
Septal Defects (A, V, AV)
Valve defects
CoA – coarctation of the aorta (narrowing of the aorta)
IAA – interupted aortic arches
Familial hypertophic cardiomyopathy
Conduction system defects
TGA – Transposition of the great arteries
PDA: patent ductus arteriosus (open duct between aorta and pulmonary artery)
DORV: double outlet right ventricle
TOF: tetraology of Fallot (pulmonary infundibular stenosis, overriding aorta, ventricular septal defect, right ventricle hypertrophy)
Stages of Heart Development
• Formation of cardiac crescent – Primary and secondary heart fields • Tube formation – Cells are added from proliferative zones at the ends of the tube • Chamber specification • Heart looping • Valve formation* • Trabeculation • Cardiac vascular development • Sinus node development
Heart Development Overview
- Cardiac crescent forms
- Cardiac crescent fuses to for the early heart tube
- If the cardiac crescent doesn’t fuse, get bilateral hearts - Heart tube tube consists of outer myocardial layer and inner endothelial (endocardial)
layer separated by cardiac jelly - Myocardium grows by adding cardiac progenitor cells at the ends of the tube from the
pharnygeal mesoderm - Heart loops to the right (first morphological feature of LR patterning)
