Partitioning Of Primordial Heart Flashcards
Around what day does the partitioning of the primordial heart occur?
Around 27th and 37th days.
What is the endocardial cushion formation?
The endocardial cushion formation separates the right atrioventricular opening from the left atrioventricular opening (L & R atrioventricular canals)
What is the purpose of the septum formation?
The septum separates the right atrium from the left atrium and the right ventricle form the left ventricle.
When does the partitioning of the primordial atrium into right and left atria occur?
Begins towards the end of 4th week.
Briefly describe the sequence of events of the partitioning of the atria into left and right.
Septum primum (sickle celled shaped crest) grows from the roof of the atrium.
The foramen secundum is formed at the upper end of the septum primum (due to cell death)
The septum secundum forms on the right of the septum primum.
The septum secundum then grows and overlaps the foramen secundum but it is incomplete as it is perforated by the oval foramen (foramen ovale)
This creates a valve known as the valve of oval foramen
What is the opening between the septum primum and the endocardial cushion called?
The optimum primum
The interventricular septum contains a muscular part and a …….. part?
Membraneous
What is the role of the oval foramen (foramen ovale)?
Before birth it allows most blood to pass from the right atrium to the left atrium because there isn’t any lungs.
It prevents the passage of blood in the opposite direction.
What happens to the oval foramen after birth?
Normally it closes due to increase in pulmonary blood flow and shift of pressure to the left atrium.
How does the oval foramen close after birth?
The septum primum fuses with the septum secundum.
What is the oval fossa in an adult heart?
It is a remnant of the oval foramen
What happens if the oval foramen doesnt close after birth?
Results in atrial septal defect (ASD) ‘hole in the heart’.
What are the 4 clinically significant types of atrial septum defect?
Foramen secundum defect
Endocardial cushion defect
Sinus venosus defect
Common atrium
Briefly describe the partitioning of primordial ventricle.
Muscular ventricular septum forms. The opening if called interventricular foramen.
Aorticopulmonary septum rotates and fuses with muscular ventricular septum to form membraneous interventricular septum, closing interventricular foramen.
Growth of the endocardial cushions separates atria from ventricles and contributes to both atrial speciation and membraneous portion of interventricular septum.
What type of ventricular septal defect is most common?
The membranous type of VSD is most common
