-
The heart precursor cells sit within the primary cardiogenic field which is
A horse shoe shaped zone of splanchnic mesoderm lying cranial and lateral to the neural plate
-
What is the first appearance of the heart in a developing embryo
Two endothelial lined tubes on the lateral to the of the neural plate on each side
-
What forms in the lateral folding of the endocardial heart tubes
The two tubes meet in the ventral midline and fuse together to make a single definitive heart tube
-
Once the endocardial tubes meet at the ventral end what happens
The cells separating the tubes undergo apoptosis making them one tube
-
What is the primitive heart tube composed of after the fusion of the two endocardial tubes
- Inner endocardial layer (inner lining of heart)
- Middle layer of cardiac jelly/extracellular matrix proteins
- Outer myocardial layer (Heart muscle)
-
Where does the epicardium come from
Mesodermal cells from near the developing liver, this is the last layer to form in the heart
-
The primitive heart has what three paired vessels flowing into it
- Vitelline veins
- Cardinal veins
- Umbilical veins
- All located on the caudal end
-
What is traveling in the Vitelline veins
Deoxygenated blood from the yolk sac
-
What is flowing in the cardinal veins
Deoxygenated blood from the body of the embryo
-
What is flowing in the umbilical veins into the heart tube
Oxygenated blood from the placenta
-
What does the truncus arteriosus become
-
What are the vessels flowing out of the heart tube
- Truncus arteriosus
- Aortic arch arteries
-
When does the heart start beating for the first time
By day 23 as the heart tube, before its folding
-
During folding of the heart tube, where does the caudal (atrium) portion go
It shifts dorsocranially and to the left
-
During folding of the heart tube, where does the ventricle portion go
It moves ventrally, caudally, and to the right
-
What are the layers of the heart tube cranial to caudal before it folds
- Truncus Arteriosus
- Bulbos cordis
- Ventricle
- Atrium
- Sinus venosus
-
When is dextrocardia lethal
When it is isolated dextrocardia, meaning the organs do not invert their positions as well
-
What is the transverse pericardial sinus
It is the the sinus that surrounds the heart (separates the inflow and outflow vessels)
-
The transverse pericardial sinus develops from
The degeneration of the dorsal mesocardium connected to the posterior body wall
-
What does the transverse pericardial sinus become postnatally
The area behind the aorta and pulmonary trunk used in heart surgery to clamp the aorta and pulmonary artery
-
What is the direction of blood flow in the heart tube
Caudal to cranial
-
What are the two origins of the right atrium
- Primitive atrium
- Right horn of the sinus venosus
-
What happens to the sizes of the sinus venosus after folding
They are originally the same size but following folding, the right horn sinus becomes larger
-
Venous return from the body and placenta enter where
The right atrium
-
When do the sinus venosus start migrating to form the atrium
Weeks 4-5
-
The right horn eventually becomes
Venae cavae
-
What happens in week 5 to the left umbilical vein, left vitelline vein, and left sinus horn
The left umbilical and vitelline are obliterated, and the left horn loses its function
-
When is the left common cardinal vein obliterated
Week 10
-
The remnants of the left sinus horn form the
Oblique vein of the left atrium and the coronary sinus
-
What feeds into the coronary sinus
The inferior venae cavae
-
What happens if the left horn does not develop properly
The coronary sinus is not developed and therefore de-oxygenated blood can't return from circulation and a spontaneous abortion will happen
-
Which part of the left umbilical vein is obliterated
The proximal end
-
The trabeculated part of the right atrium develops from
The original primitive atrium
-
The smooth portion of the right atrium develops from
The sinus venosus (smooth portion known as sinus venarum)
-
The junction between the trabaculated part of the right atrium and the smooth portion is called
Crista Terminalis
-
Remodeling of the the left atrium happens
At the same time as the right atrium
-
What develops as an outgrowth from the left atrium
A single pulmonary vein on the posterior wall
-
What happens to the pulmonary vein that begins an outgrowth from the left atrium
It divides into four branches, and connects to the blood vessels supplying the developing lungs
-
How do the proximal branches of the pulmonary branches further develop in the left atrium
They become incorporated in the posterior wall forming the smooth portion
-
What forms the rough trabaculae in the left atrium
The primitive atrium
-
What is the blood flow in the fetus from placenta to the aorta
- Placenta
- Umbilical vein
- Ductus venosus
- Inferior Vena cava
- Right atrium
- Left atrium
- Left ventricle
- Aorta
-
What are the steps to the formation of the septum
- Septum primum grows toward endocardial cushions
- Ostium primum is covered
- Ostium secundum forms in septum primum
- Septum secundum begins to form on the right side of the septum primum
- Septum secundum covers Ostium secundum
- Septum secundum leaves a hole caudal to Ostium Secundum called foramen ovale
-
When does the atrial septum begin to form
4th week
-
What forms the artial septum
- Septum primum (Thin membranous)
- Septum secundum (Thick muscular)
-
What causes the closure of the foramen ovale
After birth the pressure in the left atrium is greater then that in the right atrium forcing closure
-
Where does the Endocardial cushion form
In between the atriums and ventricles
-
What is the purpose of the septum primum covering the foramen ovale
It acts as a rudimentary valve preventing the back flow of blood from the left atrium to the right atrium
-
What are the five different types of atrial septal defects
- Probe patent foramen ovale
- Ostium Secundum effect
- Endocardial cushion defect w/ ostium primum defect
- Sinus venosus defect
- Common atrium
-
What is the most common Atrial septal defect (ASD)
Probe patent foramen present in up to 25% of people
-
What causes probe patent foramen
Incomplete adhesion of the septum primum flap to the septum secundum
-
Acyanotic heart defects
A congenital disorder manifest with left to right shunting and obstructive lesions
-
What Acyanotic conditions lead to obstruction of blood flow from the ventricles
- Coarctation of aorta
- Aortic stenosis
- Pulmonic stenosis
-
What are the Acyanotic conditions that have an increase in pulmonary blood flow
- Atrial septal defect
- Ventricular septal defect
- Patent ductus arteriosus
- Atrioventricular canal
-
What Cyanotic conditions present with decrease in pulmonary blood flow
- Tetrology of fallot
- Tricuspid Atresia
-
What cyanotic conditions present with mixed blood flow
- Transposition of great arteries
- Truncus arteriosus
- Hypoplastic left heart syndrome
- Total anomalous pulmonary venous return
-
What different defects can happen in the Ostium Secundum
- Perforations of septum primum
- A small/short septum primum
- Incomplete septum secundum development
- Combination of small primum and incomplete secundum
-
What are the symptoms of those with Ostium secundum defects
- Fatigue
- Atrial dysrythmias
- Systolic murmur
- Diastolic murmur
-
In Ostium secundum defects, what causes the Atrial dysrythmias and Systolic murmurs
- Atrial enlargement
- Increased blood flow across the pulmonary valve
-
What happens in an enlarged right atrium to cause atrial arrhythmias
The size of the atrium irritates the sinus node disrupting the regularity of the heart beat
-
What happens in an Endocardial cushion defect with ostium primum defect
- The septum primum doesn't fuse with the endocardial cushions
- Often is accompanied by a mitral valve defect called mitral valve cleft
-
What is a mitral valve cleft
A slit like hole usually in the anterior leaflet of the mitral valve
-
What is the Sinus venosus defect
- Results in the incomplete absorption of the sinus venosus into the right atrium and/or abnormal development of the septum secundum
- Pulmonary veins are often affected as well, being attached to the right atrium instead of the left
-
Common Atrium (cor tricolare biventriculare)
- Incomplete development of the atrial septal complex
- Frequently associated with heterotaxy syndrome (misplaced organs)
-
What happens in the premature closure of the foramen ovale
- The left ventricle is not developed like it should be due to less use of it during fetal development
- Hypertrophy on the right side of the heart
- Death shortly after birth
-
The bulbous cordis caudal end forms what
- The smooth part of the right ventricle (conus arteriosus)
- The smooth part of the left ventricle
-
The primitive ventricle forms what
Trabaculated part of the left and right ventricle
-
What two structures form the ventricular septum
- Muscular septum - expansion of myocardium
- Membranous septum - endocardial cushions and aortico-pulmonary septum
-
When do the ventricles begin to form
At the end of the fourth week from the movement of the myocardium
-
What is left behind in the formation of the interventricular septum
An interventricular foramen
-
When does the muscular septal formation stop
7th week (Does not fuse with the endocardial cushion)
-
What is the space in between the muscular inter-ventricular septum and cushions
Inter-ventricular foramen
-
The membranous portion of the interventricular septum is derived from
- Right side of the endocardial cushion
- Tissue form the aorticopulmonary septum
-
Many ventricular septal defects close spontaneously when
Within the first year of birth
-
Ventricular Septal Defects (VSD) are found more in
Men then in woman
-
What is the most common VSD, what is it often associated with
Membranous, aorticopulmonary septum defects
-
What can a large VSD cause problems with
- The pulmonary system due to the increase pressure from the left ventricle contraction.
- Pulmonary hypertension
- Cardiac failure in infancy
-
Swiss cheese defects are often found in the less common VSD of
Muscular VSD
-
Common ventricle septal defect
Failure of the membranous and muscular Interventricular septum to form
-
When do the atrioventricular valves form
5-8 weeks
-
What do the Artioventricular valves develop from
Local proliferations of mesenchyme surrounding the AV orifice
-
What is the conus cordis
This is the part of the bulbus cordis that tapers to merge with the truncus arteriosus
-
What triggers the formation of the AP septum
Neural crest cells migrating and invading the truncal and bulbar ridges
-
If the AP doesn't form, what else won't form
The IV membranous septum
-
The Aorticopulmonary septum divides what, and connects them to what
- Truncus arteriosus and the conus cordis into the aorta and pulmonary trunk
- It also connects the aorta to the left ventricle and the pulmonary to the right ventricle
-
Persistent truncus arteriosus
- Failure to separate truncus arteriosus, always associated with VSD
- Body and lungs receive mixed blood
-
Transposition of the great vessels
- Aorta rises from the RV and Pulmonary from the LV
- More common in males
- Maternal factors associated with rubella or other viral illness's during pregnancy
- Can be corrected surgically
-
What treatment is given to babies found to have transposition of great vessels
Prostaglandin through IV to keep the ductus arteriosus open, allowing a mixture of blood, and time to do surgery latter
-
What could cover the affects of transposition of great vessels for several weeks
A large VSD, due to the blood mixing, allowing some oxygenation in the lungs
-
What are the four abnormalities in tetralogy of fallot
- Pulmonary stenosis
- Ventricular septal defect
- Overriding aorta
- Right ventricular hypertrophy caused by higher pressure on the right side
|
|