Cardiac embryology Flashcards
What is the pathology in which a single vessel arises from the heart instead of a separate aorta and pulmonary trunk?
Common truncus arteriosus
Which embryological defect occurs in a common / persistent truncus arteriosus?
Failure of bulbar/ truncal ridge formation
Which 4 defects are present in the tetralogy of Fallot?
Pulmonary stenosis
Ventricular septal defect (VSD)
Overriding aorta
Right ventricular hypertrophy
What is transposition of the great vessels?
The aorta and pulmonary trunk are switched, so the aorta arises from the right ventricle, and the pulmonary trunk arises from the left ventricle
In which pathology is the heart positioned on the right side of the chest instead of the left?
Dextrocardia
Which day does the cardiogenic mesoderm form?
Day 18
Which day does the heart start beating in utero?
Day 22-23
What are the 5 components of the heart tube during embryological development?
Truncus arteriosus
Bulbus cordis
Primitive ventricle
Primitive atrium
Sinus venosus
In the growing heart tube, what does the truncus arteriosus become?
Ascending aorta and pulmonary trunk
In the growing heart tube, what does the bulbus cordis become?
Parts of the outflow tract of both the left and right ventricles (may form parts of the right ventricle)
In the growing heart tube, what does the primitive ventricle become?
Ventricles
In the growing heart tube, what does the primitive atria become?
Rough walled parts of the left and right atria (e.g. auricle)
In the growing heart tube, what does the sinus venosus become?
Smooth walled part of the right atrium
What does the left horn of the sinus venosus become?
Coronary sinus
What does the right horn of the sinus venosus become?
Smooth wall of the right atrium
The endocardial cushion grows between what?
The dorsal and ventral walls of the atrioventricular canal
The smooth part of the left atrial wall is formed by what?
By its growth into the pulmonary veins
The atrial septum forms during which weeks?
Weeks 4 and 5
Describe in detail the formation of the atrial septum.
- The septum primum grows downward from the roof of the common atrium toward the endocardial cushion. There is a gap between the septum primum and the endocardial cushion called the foramen primum. As the septum primum continues to grow downward, it eventually fuses with the endocardial cushion, closing the foramen primum. Before the foramen primum closes completely, apoptosis occurs in the upper portion of the septum primum, creating perforations, which coalesce to form the foramen secundum. A second, thicker septum, called the septum secundum, begins to grow to the right of the septum primum. The septum secundum grows downward but does not completely fuse, leaving a small opening called the foramen ovale. The septum primum acts as a flap valve for the foramen ovale, ensuring unidirectional blood flow during foetal life
What causes the foramen ovale to close?
Higher pressure in the left atrium pushed the septum primum against the septum secundum, forming the fossa ovalis
During which movement can right-sided atrial blood pressure exceed that on the left, resulting in a small amount of venous blood passing into the left atrium in a probe-patent foramen ovale?
Valsalva manoeuvre
Which test can be used to detect a patent foramen ovale?
Micro-bubble test
The ventricular septum is composed of which 2 types of tissue?
Muscular and membranous tissue
What are the 2 proposed causes of transposition of the great vessels?
Maldevelopment of conus arteriosus
Malformation of aorticopulmonary septum
Which 2 things cause the closure of the ductus arteriosus after birth?
Increase in blood oxygen levels (PaO2) and decrease in prostaglandin E2 levels
Aortic coarctation can be classified relative to its positional relationship to what?
Ductus arteriosus – preductal, juxtaductal, postductal
